NASA Technical Memorandum 4677

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Microgravity Science & Applications

Program Tasks and Bibliography

for FY1994

March 1995

National Aeronautics and

Space Administration

Office of Life and Microgravity

Sciences and Applications

Microgravity Science and Applications Division

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NASA Technical Memorandum 4677

Microgravity Science & Applications

Program Tasks and Bibliography

for FY 1994

Microgravity Science and Applications Division

NASA Headquarters, Code UG

Washington, DC 20546-0001

National Aeronautics and

Space Administration

Office of Management

Scientific and Technical

Information Program

March 1995

4,....................................................................................

I. INTRODUCTION .................................................................................................................................... 1

II. MICROGRAVITY SCIENCE & APPLICATIONS PROGRAM TASKS .................... 5

Flight: Benchmark Science

Critical Dynamics in Microgravity (Dr. Robert V. Duncan) ................................................................... 7

Statellite Test of the Equivalence Principle (Prof. C.F. Everitt) ................................................................ 11

Critical Dynamics of Fluids (Prof. Richard A. Ferrell) .......................................................................... 13

Critical Fluid Light Scattering Experiment (ZENO) (Prof. Robert W. Gammon) .............................. 15

Heat Capacity Measurements Near the Lambda Point of Helium (Prof. John A. Lipa) ........................ 17

Confined Helium Experiment (CHeX) (Prof. John A. Lipa) .................................................................. 19

Critical Fluid Thermal Equilibrium Dynamics (Dr. R. Allen Wilkinson) ............................................. 21

Flight: Biotechnology

Protein Crystal Growth Vapor-Diffusion Flight Hardware and Facility (Dr. Daniel C. Carter) .......... 23

Advanced High Brilliance X-Ray Source (Dr. Daniel C. Carter) ............................................................. 25

Protein Crystal Growth in Microgravity (Dr. Lawrence J. Delucas) .................................................... 27

Electrophoretic Separation of Cells and PartT'cles from Rat Pituitary (Dr. Wesley C. Hymer) ............. 29

An Observable Protein Crystal Growth Flight Apparatus (Dr. Alexander McPherson, Jr.) ............... 31

Electrophoresis Technology (Dr. Robert S. Snyder) ................................................................................ 34

Flight: Combustion Science

Scienttific Support for an Orbiter Middeck Experiment

on Solid Surface Combustion (Prof. Robert A. Altenkirch) .................................................................. 36

Low-Velocity, Opposed-Flow Flame Spread in a

Transport-Controlled, Microgravity Environment (Prof. Robert A. A]tenkirch) ................................ 38

Reflight of the Solid Surface Combustion Experiment with

Emphasis on Flame Radiation Near Extinction (Prof. Robert A. Altenkirch) ......................................... 41

Gravitational Effects on Laminar, Transitional, and Turbulent

Gas-Jet D!{fusion Flames (Dr. M. Yousef Bahadori) .............................................................................. 43

Sooting Effects in Reduced Gravity Droplet Combustion (SEDC) (Prof. Mun Y. Choi) ........................ 46

Candle Flames in Microgravity (Dr. Daniel L. Dietrich) ........................................................................ 48

Investigation of Laminar Jet Diffusion Flames in Microgravity:

A Paradi,gmfor Soot Processes in Turbulent Flames (Prof. Gerard M. Faeth) ...................................... 50

Unsteady D!ffusion Flames: Ignition, Travel, and Burnout (Dr. Frank Fendeli) ..................................... 54

Fundamental Study of Smoldering

Combustion in Microgravity (Prof. A. Carlos Fernandez-Pello) ......................................................... 56

Ignition and the Subsequent Transition to

Flame Spread in Microgravity (Dr. Takashi Kashiwagi) ........................................................................ 59

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MSAD Program Tasks & Bibliography-- FY1994 Table of Contents

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Studies of Premixed Laminar and Turbulent

Flames at Microgravity (Prof. Paul D. Ronney) .................................................................................... 60

Ignition and Flame Spread of Liquid Fuel Pools (Dr. Howard Ross) ...................................................... 63

Combustion of Solid Fuel in Very Low Speed Oxygen Streams (Prof. James S. T'ien) ........................... 66

Droplet Combustion Experiment (Prof. Forman A. Williams) .............................................................. 69

Flight: Fluid Physics

Surface Controlled Phenomena (Dr. Robert E. Apfel) ............................................................................. 72

Critical Viscosity of Xenon (Dr. Robert F. Berg) ...................................................................................... 74

The Dynamics of Disorder-Order Transitions in

Hard Sphere Colloidal Dispersions (Prof. Paul M. Chaikin) .................................................................. 76

Kinetics of Diffusional Droplet Growth (Dr. Donald O. Frazier) ........................................................... 78

Microscale Hydrodynamics Near Moving Contact Lines (Prof. Stephen Garoff) .................................. 80

Plasma Dust Crystallization (Dr. John A. Goree) ................................................................................... 83

Evaporation from a Meniscus within a Capillary Tube in Microgravity (Prof. Kevin P. Hallinan) ...... 85

Geophysical Fluid Flow Cell (Dr. John E. Hart) ....................................................................................... 87

Interracial Phenomena in Multilayered Fluid Systems (Prof. Jean N. Koster) ....................................... 89

Extensional Rheology of Non-Newtonian Materials (Prof. Gareth H. McKinley) ................................. 91

Pool Boiling Experiment (Prof. Herman Merte, Jr.) ............................................................................... 93

Surface Tension-Driven Convection Experiment (STDCE-1, STDCE-2) (Prof. Simon Ostrach) ......... 96

Modeling and New Experiment Definition for the VIBES (Prof. Robert L. Sani) .................................. 99

Studies in EIectrohydrodynamics (Dr. Dudley A. Saville) .................................................................... 101

Mechanics of Granular Materials (Dr. Stein Sture) ............................................................................... 103

Thermocapillary Migration and Interactions of

Bubbles and Drops (Prof. R. Shankar Subramanian) ........................................................................... 105

Drop Dynamics Investigation (Dr. Taylor G. Wang) ............................................................................ 107

Colloid Physics in Microgravity (Dr. David A. Weitz) ......................................................................... 109

Study of Two Phase Flow Dynamics and Heat

Transfer at Reduced Gravity (Prof. Larry Witte) .................................................................................... 110

Flight: Materials Science

In Situ Monitoring of Crystal Growth Using MEPHISTO (Prof. G.J. Abbaschian) .......................... 112

Coupled Growth in Hypermonotectics (Dr, J. Barry Andrews) ............................................................ 115

Effects on Nucleation by Containerless Processing (Prof. Robert J. Bayuzick) .................................... 117

Alloy Undercooling Experiments in

Microgravity Environment (Prof. Merton C. Flemings) ...................................................................... 119

Compound Semiconductor Growth in Low-g Environment (Dr. Archibald L. Fripp) ......................... 120

Melt Stabilization of PbSnTe in a Magnetic Field (Dr. Archibald L. Fripp) ........................................ 122

Gravitational Role in Liquid-Phase Sintering (Prof. Randall M. German) .......................................... 124

Isothermal Dendritic Growth Experiment (Prof. Martin E. Glicksman) .............................................. 126
MSAD Program Tasks & Bibliography -- FY1994 Table of Contents

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Evaluation of Microstructural Development in

Undercooled Allous (Dr. Richard N. Grugel) ........................................................................................ 129

Thermophysical Properties qf MetalIic Glasses and

Undercooled Alloys (Dr. William L. Johnson) ...................................................................................... 131

Orbital Processing of High Quality Cadmium Telluride (Dr. David J. Larson) ................................... 133

Crystal Growth of II-IV Semieonducting Alloys by

Directional Solidification (Dr. Sandor L. Lehoczky) ............................................................................ 137

Growth of Solid Solution Single Crystals (Dr. Sandor L. Lehoczky) ..................................................... 139

GaAs Crystal Growth Experiment (Dr. David H. Matthiesen) ............................................................ 141

Diffusion Processes in Molten Semiconductors (Dr. David H. Matthiesen) ........................................ 142

The Study of Dopant Segregaton Behavior

During the Growth of GaAs in Microgravity (Dr. David H. Matthiesen) .......................................... 144

Temperature Dependence of Diffusivities in Liquid Metals (Prof. Franz Rosenberger) ...................... 145

Double Diffusive Convection during Growth of Lead Bromide Crystals (Dr. N.B. Singh) ................... 147

Particle Engulfment and Pushing by Solid!lying Interfaces (Dr. Doru M. Stefanescu) ...................... 149

Crystal Growth qf ZnSe and Related Ternary Compound

Semiconductors by Physical Vapor Transport (Dr. Ching-Hua Su) ..................................................... 151

Measurement of Viscosity and

Surface Tension of Undercooled Melts (Dr. Julian Szekely) .................................................................. 153

Test of Magnetic Damping of Convective Flows in Microgravity (Dr. Frank R. Szofran) ................... 155

Vapor Growth of AIIoy-Type Semiconductor Crystals (Dr. Heribert Wiedemeier) ............................ 157

Ground: Benchmark Science

SuperJluid Transition of_He in the Presence of a Heat Current (Prof. Guenter Ahlers) ..................... 159

Microgravity Test of Universality and Scaling Predictions

Near the 3He Critical Point (Dr. Martin B. Barmatz) ........................................................................... 161

Measurement of the Heat Capacity of Super fluid

Helium in a Persistent Current State (Dr. Taiso C. P. Chui) ................................................................ 163

Nonequilibrium Phenomena Near the Lambda

Transition of 4He (Dr. Talso C. P. Chui) ................................................................................................. 165

Determination of the Correlation Length in

Helium II in a Microgravity Environment (Prof. Russell Donnelly) ................................................... 166

Nucleation of Quantized Vortices from Rotating Superfluid Drops (Prof. Russell J. Donnelly) ......... 168

Kinetic and Thermodynamic Studies of Melting-Freezing of

Helium in Microgravity (Prof. Charles EIbaum) .................................................................................. 170

Theoretical Influence of Microgravity on Critical

Fluid Measurements (Prof. Richard A. Ferrell) ..................................................................................... 172

Condensate Fraction in Superfluid Helium Droplets (J. Woods Halley) .............................................. 173

Ultra-Precise Measurements with Trapped

Atoms in a Microgravity Environment (Dr. Daniel J. Heinzen) ........................................................... 176

Dynamic Measurement Near the Lambda-Point in a

Low-g Simulator on the Ground (Dr. UIf E. Israelsson) ........................................................................ 178
Turbidity of a Binary Mixture Very Close to the Critical Point (Prof. Donald T. Jacobs) .................... 180

Atom lnt_fierometry in a Microgravity Environment (Dr. Mark A. Kasevich) ................................... 182

Effect qf Confinement on Transport Properties by Making

Use of Helium Near the Lambda Point (Prof. John A. Lipa) .................................................................. 184

Theoretical Studies of the Lambda Transition of Liquid 4He (Efstratios Manousakis) ........................ 185

Dynamics and Morphology of Superfluid

Helium Drops in a Mierogravity Environment (Prof. Humphrey J. Maris) ........................................ 188

Critical Transport Phenomena in Fluid Helium Under Low Gravity (Prof. Horst Meyer) ................. 190

Equilibration in Density and Temperature near the

Liquid-Vapor Critical Point (Prof. Horst Meyer) .................................................................................. 192

Nonlinear Dynamics and Nucleation Kinetics

in Near-Critical Liquids (Prof. Alexander Z. Patashinski) .................................................................. 195

Precise Measu remen ts of the Density an d Thermal Expansion

of 4 HeHear the Lambda Transition (Dr. Donald M. Strayer) ............................................................... 196

Ground: Biotechnology

Evaluation of Ovarian Tumor Cell Growth and Gene Expression (Jeanne L. Becker, Ph.D.) ............. 198

Crystallographic Studies of Proteins Part II (Dr. Daniel C. Carter) ...................................................... 200

Microgravity Studies of CeII-Polymer Cartilage Implants (Lisa E. Freed, M.D., Ph.D.) ..................... 202

Excitable Cells and Growth Factors under Microgravity Conditions (Charles R. Hartzell, Ph.D.) .... 205

Sensitized Lymphocytes for Tumor Therapy Grown in Microgravity (Marylou Ingram, M.D.) ......... 208

Three-Dimensional Modeling of Human Colon Tissues (J. Milbum Jessup, M.D.) ............................. 211

Three-Dimensional Tissue Interactions in

Colorectal Cancer Metastasis (J. Milbum Jessup, M.D.) ...................................................................... 213

Applications of Atomic Force Microscopy to Investigate

Mechanisms of Protein Crystal Growth (Dr. John H. Konnert) ............................................................ 216

Neuro-endocrine Organoid Assembly in Vitro (Peter I. Lelkes, Ph.D.) ................................................ 218

Formation of Ordered Arrays of Proteins on Surfaces (Prof. Abraham M. Lenhoff) ........................... 223

Crystallization Studies in Mierogravity of an Integral Membrane Protein:

The Photosynthetic Reaction Center (Dr. James R. Norris) .................................................................. 225

Shear Sensitivities of Human Bone Marrow Cultures (Bernhard O. Palsson, Ph.D.) ......................... 228

Microgravity Crystallization of Avian Egg White Ovostatin (Dr. Marc L. Pusey) .............................. 229

Study of Crystallization and Solution Properties of

Redesigned Protein Surfaces (Prof. David C. Richardson) .................................................................. 231

Convective Flow Effects on Protein Crystal Growth and

Diffraction Resolution (Prof. Franz E. Rosenberger) ........................................................................... 233

Enhancement of Cell Function in Culture by Controlled Aggregation (W. M. Saltzman) ................... 236

Culture of Porcine Islet Tissue: Evaluation of

Microgravity Conditions (David W. Scharp) ........................................................................................ 239

Automation of Protein Crystallization Experiments:

Crystallization by Dynamic Control of Temperature (Dr. Keith B. Ward) ........................................... 241

Thermal Optimization of Grcnvth and Quality of Protein Crystals (Dr. John M. Wiencek) ................ 243
MSAD Program Tasks & Bibliography -- FY1994 Table of Contents

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Search for Dilute Solution Property to Predict Protein O_stallization (Dr. W. William Wilson) ...... 246

Characterization qf Solvation Potentials Between Small Particles (Dr. Charles F. Zukoski) ................ 248

Ground: Combustion Science

Effects of Energy Release on Near Field

Flow Structure qfiGas lets (Prof. Ajay K. Agrawal) .............................................................................. 250

Radiative Extinction of Diffusion Flames (Prof. Arvind Atreya) ......................................................... 252

Multicomponent Droplet Combustion in Microgravity: Soot Formation, Emulsions,

Metal-Based Additives, and the Effect of Initial Droplet Diameter (Prof. C.T. Avedisian) ................... 254

Development of Advanced Diagnostics for Characterization

of Burning Droplets in microgravity (Dr. William D. Bachalo) ............................................................ 255

Ignition and Combustion of Bulk Metals in Micrqgravity (Prof. Melvyn C. Branch) ......................... 256

Ignition and Combustion of Bulk Metals in Microgravity (Prof. Melvyn C. Branch) ......................... 258

Modeling of Micro_ravity Combustion Experiments (Prof. John C. Buckmaster) .............................. 259

Buoyancy Effects on the Structure and Stability

of Burke-Schumann Difh¢sion Flames (Prof. L.D. Chen) ........................................................................ 263

Gravitational Effects on Premixed Turbulent Flames (Dr. Robert K. Cheng) ...................................... 266

Gravitational Effects on Premixed Turbulent Flames :

Microgravity Flame Structures (Dr. Robert K. Cheng) ........................................................................ 268

Combustion of Interacting Droplet Arrays in

a Microgravity Environment (Dr. Daniel Dietrich) .............................................................................. 269

Internal and Surf. ace Phenomena in

Heterogeneous Metal Combustion (Dr. Edward L. Dreizin) ................................................................. 271

Flame-Vortex Interactions hnaged in Microgravity (Prof. James F. Driscoll) ...................................... 273

Aerodynamic, Unsteady, Kinetic, and Heat Loss Effects on the Dynamics and

Structure of Weakly-Burning Flames in Microgravity (Prof. Fokion N. Egolfopouios) .................... 275

Effects qflGravity on Sheared and Nonsheared

Turbulent Nonpremixed Flames (Prof. Said E. Elghobashi) ................................................................ 276

Combustion of Electrostatic Sprays of Liquid Fuels in

Laminar and Turbulent Regimes (Prof. Alessandro Gomez) .............................................................. 278

Three-Dimensional Flow in a Microgravity Diffusion Flame (Prof. Jean R. Hertzberg) ..................... 280

Chemical Inhibitor Effects on Diffusion Flames in Microgravity (Prof. Simone Hochgreb) ................ 282

Time-Dependent Computational Studies of Pre-Mixed Flames (Dr. K. Kailasanath) .......................... 285

Radiative Ignition and Transition to Flame Spread in Microgravity (Dr. Takashi Kashiwagi) .......... 288

Sooting Turbulent let Diffusion Flames (Prof. Jerry, C. Ku) .................................................................. 291

Soot and radiation Measurements in Microgravity

Turbulent Jet D((f-usion Flames (Prof. Jerry, C. Ku) ............................................................................... 293

Studies of Flame Structure in Microgravity (Prof. Chung K. Law) ..................................................... 294

Structure and Dynamics qflDiffusion Flames in Microgravity (Prof. Moshe Matalon) ....................... 296

Filtration Combustion for Microgravity Applications: (1) Smoldering, (2)Combustion

Synthesis of Advanced Materials (Prof. Bernard J. Matkowsky) .......................................................... 298
MSAD Program Tasks & Bibliography -- FY1994 Table of Contents

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Combustion of PTFE: The Effect of Gravity on the Production

of Ultrafine Particles Generation (Prof. J.T. McKinnon) ........................................................................ 300

Premixed Turbulent Flame Propagation in Microgravity (Prof. Suresh Menon) ................................. 302

A Fundamental Study of the Combustion Syntheses qfiCeramic-Metal Composite Materials

Under Microgravity Conditions (Prof. John J. Moore) ......................................................................... 304

Flow and Ambient Atmoshere Effects on

Flame Spread at Microx, ravity (Prof. Paul D. Ronney) .......................................................................... 307

Combustion Research (Dr. Howard Ross) ............................................................................................. 309

Combustion of Solid Fuel in Very Low Speed Oxygen Streams (Kurt R. Sacksteder) .......................... 315

Reduced Gravity with 2-Component Miscible Droplets (Prof. Benjamin Shaw) .................................. 317

Quantitative Measurement of Molecular Oxygen

in Microgravity Combustion (Dr. Joel A. Silver) .................................................................................... 320

Numerical Modeling of Flame-Balls in Fuel-Air Mixtures (Prof. Mitchell D. Smooke) ...................... 322

Combustion of Solid Fuel in Very Low Speed Oxygen Streams (Prof. James S. T'ien) ........................ 323

Interactions Between Flames on Parallel Solid Surfaces (Dr. David L. Urban) ..................................... 325

Gasless Combustion Synthesis from Elements Under Microgravity:

A Study of Structure-Formation Processes (Prof. Arvind Varma) ....................................................... 327

Studies of Wind-Aided Flame Spread Over Thin

Cellulosic Fuels in Microgravity (Prof. Indrek S. Wichman) ................................................................ 329

High Pressure Droplet Combustion Studies (Prof. Forman A. Williams) ........................................... 330

High-Pressure Combustion of Binary Fuel Sprays (Prof. Forman A. Williams) .................................. 331

Laser Diagnostics for Fundamental Microgravity

Droplet Combustion Studies (Dr. Michael Winter) .............................................................................. 333

Combustion of a Polymer (PMMA) Sphere in Microgravity (Dr. Jiann C. Yang) ................................. 335

Ground: Fluid Physics

Study of Two-Phase Flow and Heat Transfer in Reduced Gravities (Dr. Davood Abdollahian) ........ 337

Colloids & Nucleation ( Prof. Bruce J. Ackerson) .................................................................................. 339

Stability Limits and Dynamics of Nonaxisymmetric Liquid Bridges (Dr. lwan D. Alexander) .......... 340

Investigation of Multiple-Layer Convection (Prof. C.D. Andereck) ...................................................... 342

Electrokinetic Transport of Heterogeneous Particles in Suspensions (Prof. John L. Anderson) .......... 344

Experimental Study of Liquid let Impingement

in Microgravity: The Hydraulic ]ump (Prof. C.T. Avedisian) .............................................................. 346

Studies on the Response of Emulsions to Externally-Imposed Electric and Velocity Fields:

Electrohydrodynamic Deformation and Interaction of a Pair of Drops (Dr. James C. Baygents) ........ 347

Marangoni Effects in Boiling of Binary Fluid

Mixtures Under Microgravity (Prof. Van P. Carey) ............................................................................. 349

Marangoni Instability Induced Convection in Evaporating Liquid Droplets (Dr. An-Ti Chai) ........... 350

Rewetting of Monogroove Heat Pipe in Space Station Radiators (Prof. S. H. Chan) ............................ 352

Marangoni and Double-Diffusive Convection in a

Fluid Layer under MicroRravity (Prof. Chuan F. Chen) ....................................................................... 354
MSADProgram Tasks & Bibliography -- FY1994 Table of Contents

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Transport Phenomena in Strat!fied Flow in the

Presence and Absence qfGravity (Dr. Norman Chigier) ...................................................................... 356

Bubble Dynamics, Two-Phase Flow, and Boiling

Heat Transfer in Microgravity (Prof. Jacob N Chung) ........................................................................ 358

Reactive Fluids Experiment: Chemical Vapor Deposition (Dr. Ivan O. Clark) ..................................... 360

Microgravity Particle Dynamics (Dr. Ivan O. Clark) ............................................................................ 362

Studies of Freely Suspended Liquid Crystal Bubbles (Prof. Noel A. Clark) .......................................... 364

Fluid Interface Behavior Under Low- and Reduced-Gravity Conditions (Prof. Paul Concus) ............. 365

Convection and Morphological Stability During Directional Solidification (Prof. Sam R. Coriell) .... 369

Microphysics of Close Approach and Film Drainage

and Rupture During Drop Coalescence (Prof. Robert H. Davis) .......................................................... 371

Phase Segregation Due to Simultaneous Migration and Coalescence (Prof. Robert H. Davis) ............ 373

Interaction and Aggregation of Colloidal Biological

Particles and Droplets in Electrically-Driven Flows (Prof. Robert H. Davis) ...................................... 375

Theory of Solid!fication (Prof. Stephen H. Davis) ................................................................................. 377

Microgravity Foam Structure and Rheology (Prof. Douglas J. Durian) .............................................. 378

The Influence of Gravity on Nucleation, Growth, Stability

and Structure in Ordering Soft-Spheres (Prof. Alice P. Gast) ............................................................... 380

Fluid Mechanics of Capillary Elastic Instabilities

in the Microgravity Environment (Prof. James B. Grotberg) ............................................................... 382

Effects of Convection on the Thermocapillary Motion of

Deformable Drops (Prof. Hossein Haj-Hariri) ...................................................................................... 383

Interracial Transport and MicelIar Solubilization Processes (Prof. T. Alan Hatton) ............................ 385

Critical Phenomena, Electrodynamics, and Geophysical Flows (Dr. John Hegseth) .............................. 387

Thermocapillary Instabiilties and g-Jitter Convection (Prof. George M. Homsy) ............................... 388

Kinetic and Transport Phenomena in a Microgravity Environment (Prof. David Jasnow) ................. 390

Surfactant Based Critical Phenomena in Microgravity (Dr. Eric W. Kaler) ......................................... 392

Instability of Velocity and Temperature Fields in the

Vicinity of a Bubble on a Heated Surface (Dr. Mohammad Kassemi) ................................................. 394

Stabilization of Thermocapillary convection by Means of

Nonplanar Flow Oscillations (Prof. Robert E. Kelly) ............................................................................ 396

Microgravity Heat Transfer Mechanisms in the Nucleate Pool Boiling and Critical

Heat Flux Regimes Using a Novel Array of Microscale Heaters (Prof. Jungho Kim) .......................... 398

Molecular Dynamics of Fluid-Solid Systems (Dr. Joel Koplik) ............................................................. 400

Fluid Dynamics and Solidification of Metallic Melts (FDSMM) (Prof. Jean N. Koster) ..................... 402

Thermocapillary Convection in Floating Zones Under

Simulated Reduced Gravity (Prof. Sindo Kou) ...................................................................................... 404

Analysis of Phase Distribution Phenomena in

Microgravity Environments (Prof. Richard T. Lahey) .......................................................................... 406

Nonlinear Drop Dynamics and Chaotic Phenomena (Dr. L. Gary, Leal) ............................................... 408
MSAD Program Tasks & Bibliography -- FY1994 Table of Contents

Oscillatory Cross-Flow Electrophoresis:

Application to Production Scale Separations (Dr. Davis T. Leighton) .................................................. 411

Low Dimensional Models for ThermocapilIary Convective

Flows in Crystal Growth Processes (Prof. A. Liakopoulos) .................................................................. 412

Absolute and Convective Instability of a Liquid Jet at Microgravity (Prof. Sung P. Lin) ..................... 413

Magnetorheological Fluids in Micrgravity (Prof. Jing Liu) .................................................................... 415

Cross Effects in Microgravity Flows (Prof. Sudarshan K. Loyalka) .................................................... 417

Controlling the Mobility of a Fluid Particle in Space

by Using Remobilizing Surfactants (Prof. Charles Maldarelli) ............................................................ 419

Stabilization and Low Frequency Oscillations of Capillary Bridges

with Modulated Acoustic Radiation Pressure (Prof. Philip L. Marston) .............................................. 421

Study of Disturbances in Fluid-Fluid Flows in

Open and Closed Systems (Prof. Mark J. McCready) ........................................................................... 423

Study of Forced Convection Nucleate Boiling in Microgravity ( Prof. Herman Merte, Jr.) ................ 424

Control of Oscillatory Thermocapillary Convection in Microgravity (Prof. G. Paul Neitzel) ............. 426

Industrial Processes (Prof. Simon Ostrach) ........................................................................................... 428

Marangoni Effects on the Bubble Dynamics

in a Pressure Driven Flow (Prof. Chang-Won Park) ............................................................................. 430

Two-Phase Interfaces in Weak External Fields (Prof. Jerome K. Percus) ............................................. 431

Containerless Capillary Wave Turbulence (Dr. Seth J. Putterman) ...................................................... 433

Studies of Radiation-Driven and Buoyancy-Driven

Fluid Flows and Transport (Prof. Paul D. Ronney) ............................................................................... 435

Fluid Creep Effects on Near-Wall Solute Transport for Non-Isothermal

Ampoules and Suspended Particle Transport Coefficients (Prof. Daniel E. Rosner) ............................. 437

Dynamics of Superfluid Helium in Low Gravity (Dr. Graham Ross) ................................................... 438

Microscate Modeling ofMicrogravity Multiphase Flow (Dr. Paul H. Rot.he) ...................................... 440

Gas Flow from Porous Media and Microgravity Battery Spills (Dr. Robert T. Ruggeri) ...................... 441

Ground-Based Studies q( ThermocapiIlary Flows in Levitated Drop (Dr. Satwindar S. Sadhal) ......... 443

Effects of Gravity and Shear on the Dynamics and

Stability of Particulate and Multiphase Flows (Prof. Ashok S. Sangani) ............................................. 446

Dielectric and Electrohydrodynamic Properties of Suspensions (Dr. Dudley A. Saville) ..................... 448

Electrohydrodynamic Pool Boing in reduced Gravity (Prof. Banjamin D. Shaw) ................................ 450

Transport Processes Research (Dr. Bhim S. Singh) ................................................................................ 451

Solute Nucleation and Growth in Supercritical Fluid Mixtures (Dr. Gregory T. Smedley) ............... 453

Behavior of Unsteady Thermocapillary Flows (Prof. Marc K. Smith) ................................................... 454

Flow-Influenced Shape Stability: Breakup in Low Gravity (Prof. Paul H. Steen) ................................ 457

Interactions of Bubbles and Drops in a Temperature Gradient (Prof. R. Shankar Subramanian) ...... 459

Instability in Surface-Tension-Driven Benard Convection (Prof. Harry L. Swinney) ........................ 461

Crystal Growth and Fluid Mechanics Problems in

Directional Solidification (Prof. Saleh Tanveer) .................................................................................... 463

OscillatoryChaotic Thermocapillary Flow Induced by

Radiant Heating (Dr. Robert L. Thompson) ......................................................................................... 465

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MSAD Program Tasks & Bibliography -- FY1994 Table of Contents

Light Scattering Studies of Relative Motions of

Solid Particles in Turbulent Flows (Prof. Penger Tong) ........................................................................ 467

Computational Studies of Drop Collision and Coalescence (Prof. Gretar Tryggvason) ....................... 468

Nonlinear Bubble Interactions in Acoustic Pressure Fields (Prof. John Tsamopoulos) ....................... 470

Residual Accelerations in a Microgravity Environment (Prof. Jorge Vitals) ....................................... 472

Studies of the Dynamics of Charged Free Drops (Dr. Taylor G. Wang) ............................................... 474

Experimental Study of the Vapor Bubble Thermosyphon (Prof. Peter C. Wayner, Jr.) ........................ 476

Interactions Between Solidification and Compositional

Convection in Alloys (Prof. M. Grae Worster) ...................................................................................... 478

Nucleation and ChiraI Symmetry Breaking under Hydrodynamic Flows (Dr. Xiao-lun Wu) .............. 479

Oscillatory Thermocapillary Convection (Prof. Abdelfattah Zebib) .................................................... 481

Ground: Materials Science

Synthesis and Characterization of Single Macromolecules: Mechanistic

Studies of Crystallization and Aggregation (Prof. Spiro D. Alexandratos) ......................................... 483

A Novel Electrochemical Method of Flow Visualization (Dr. T.J. Anderson) ........................................ 485

Foam Metallic Glasses (Prof. Robert E. Apfel) ...................................................................................... 487

Nucleation and Cluster Formation in Levitated Drops (Prof. Stephen Arnold) ................................... 489

Microwave Materials Processing in Microgravity (Dr. Martin B. Barmatz) ........................................ 491

Studies of Containerless Processing of Selected Alloys (Prof. Robert J. Bayuzick) .............................. 493

Studies of Nucleation and Growth of lntermetallic Compounds (Dr. Robert J. Bayuzick) .................. 495

Transport Phenomena During Equiaxed Solidification of Alloys (Prof. Christoph Beckermann) ...... 497

Gravitational Effects on the Development of Weld-Pool and

Solidification Microstructures in Metal Alloy Single Crystals (Dr. Lynn A. Boatner) ........................ 500

Modeling of Convection and Crystal Growth in Directional

Solidification of Semiconductor and Oxide Materials (Prof. Robert A. Brown) ................................... 502

Microstructure Formation During Directional Solidification of

Binary Alloys without Convection: Experiment and Computation (Prof. Robert A. Brown) ............. 505

Evolution of Crystals and Amorphous Phase Structure

During Processing of Thermoplastic Polymers (Dr. Peggy Cebe) ......................................................... 508

Optical Propert_'es for High Temperature Materials Research (Dr. Ared Cezairliyan) ........................ 510

Fluid Mechanics of Directional Solidification

at Reduced Gravity (Prof. Chuan F. Chen) ........................................................................................... 512

Microgravity Chemical Vapor Deposition (Dr. Ivan O. Clark) ............................................................. 513

Glass Formation and Nucleation in Microgravity: Containerless-Processed,

Inviscid SilicateOxide Melts [Ground-Based Studies] (Dr. Reid F. Cooper) ...................................... 515

Directional Solidification in 3He-4He Alloys (Prof. Arnold Dahm) ..................................................... 518

Advanced Photonic Materials Produced by Containerless Processing (Dr. Delbert E. Day) ................ 520

The Effect of Gravity on Natural Convection and

Crystal Growth (Prof. Graham D. deVahl Davis) ............................................................................... 524

Use of Synchrotron White Beam X-Ray Topography for the Characterization of the Microstructural

Development of Crystal- Normal Gravity Versus Microgravity (Dr. Michael Dudley) ...................... 526

_o_iu_*_1_*_m_1*_a*iau*_*_**_I_*_o_o_o_*_a_a**_*u*_j*_ao_aoia_D_*_a_*_o_a*mm*o_*_a¢na_I_*o*u_a¢n_*_n*o_*oo_mi*_*_a_u*mm_ona*_*_*_*no_*¢_aoIIa*no_mIa_l*_j_a*_a*_a*_*_

xi
Reverse Micelle Based Synthesis of Microporous Materials in Microgravity (Prof. P.K. Durra) .......... 530

Growth of Nonlinear Optical Thin Fihns/Vapor Processes (Dr. Donald O. Frazier) ........................... 531

Growth of Nonlinear Optical Crystals by Melt and Solution Processes (Dr. Donald O. Frazier) ....... 533

Investigation of Local Effects on Microstructure Evolution (Dr. Donald O. Frazier) .......................... 535

Electronic Materials (Dr. Thomas K. Glasgow) .................................................................................... 537

Combustion Synthesis of Materials in Microgravity (Prof. Dr. Irvin Glassman) ................................ 538

Evolution of Microstructurat Distance Distributions

in Normal Gravity and Microgravity (Dr. Arun M. Gokhale) .............................................................. 540

Influence of Free Convection in Dissolution (Prof. Prabhat K. Gupta) ................................................. 541

Noncontact Thermal, Physical Property Measurement of

Multiphase Systems (Dr. Robert H. Hauge) ......................................................................................... 542

Mierogravity Processing of Oxide Superconductors (Dr. William Hoffmeister) .................................. 544

Non-Equilibrium Phase Transformations (Dr. Kenneth A. Jackson) ................................................... 546

Combined Heat Transfer Analysis of Crystal Growth (Dr. Mohammad Kassemi) ............................. 548

Fundamentals of Thermomigration of Liquid Zones through Solids (Prof. Michael J. Kaufman) ....... 550

Kinetics of Phase Transformations in Glass Forming (Prof. Kenneth F. Kelton) ................................. 552

Compositional Dependence of Phase Formation and Stability (Prof. Kenneth F. Keiton) .................... 554

SolutocapiUary Convection Effects on

Polymeric Membrane Morphology (Prof. William B. Krantz) ............................................................... 555

Containerless Property Measurement of High-Temperature Liquids (Dr. Shankar Krishnan) ............ 557

Noise and Dynamical Pattern Selection in Solidification (Prof. Douglas A. Kurtze) ........................... 560

Chemical Vapor Deposition of High-tcSuperconducting Fihns in a

Microgravity Environment (I) (Prof. Moises Levy) .............................................................................. 561

Microstructural Development during Directional Solidification of

Peritectic Alloys (Dr. Thomas A. Lograsso) ......................................................................................... 563

Numerical Investigation of Thermal Creep and Thermal Stress Effects in

Microgravity Physical Vapor Transport (Dr. Daniel W. Mackowski} ................................................ 565

Polymerizations in Microxravity: Traveling Fronts, Dispersions,

Diffusion and CopoIymerizations (Prof. Lon J. Mathias) ...................................................................... 568

Quantitative Analysis of Crystal Defects by

Triple Crystal X-Ray Diffraction (Dr. Richard J. Matyi) ...................................................................... 571

The Interactive Dynamics of Convection, Flow and

Directional Solidification (Prof. T. Maxworthy, Ph.D.) ........................................................................ 573

Y2BaCu05 Segregation in YBa2Cu3OT_x During Melt Texturing (Dr. Paul J. McGinn) .................... 574

Interaction of Hele-Shaw Flows with Directional Solidification: Numerical Investigation of the

Nonlinear Dynamical Interplay and Control Strategies (Prof. Eckart H. Meiburg) ............................ 576

The Synergistic Effect of Ceramic Materials Synthesis Using

Vapor-Enhanced Reactive Sinterin X Under Microgravity Conditions (Prof. John J. Moore) .............. 578

Diffusion, Viscosity, and Crystal Growth in Microgravity (Prof. Allan S. Myerson) ......................... 580

An Electrochemical Method to Measure Diffusivity in Liquid Metals (Prof. Ranga Narayanan) ...... 582

Crystal Growth and Segregation Using the Submerged Heater Method (Prof. A.G. Ostrogorsky) .... 584
MSAD Program Tasks & Bibliography -- FY1994 Table of Contents

Investigation q{ "'Contactless" Crystal Growth

by Physical Vapor Transport (Dr. Witold Paiosz) .................................................................................. 586

Conta_nerless Processing for Controlled

Solidification Microstructures (Prof. John H. Perepezko) .................................................................... 587

ContainerIess Processing for Composite Materials (Prof. John H. Perepezko) ..................................... 589

Comparison q{ the Structure and Segregation in Dendritic Alloys Solidified in

Terrestrial and Low Gravity Environments (Prof. David R. Poirier) ................................................... 591

Kinetics of Phase Transformation in Glass Forming Systems (Dr. Chandra S. Ray) ........................... 593

The Effects of Microgravity on Vapor Phase Sintering (Prof. Dennis W. Readey) .............................. 595

Modeling of Detached Solidification (Dr. Liya L. Regel) ....................................................................... 599

Electrostatic Containerless Processing (Dr. Won-Kyu Rhim) .............................................................. 601

Drop Tube Operation (Dr. Michael B. Robinson) ................................................................................. 604

Measuremen t of the Optical and radiative Properties of High-Temperature

Liquid Materials by FTIR Spectroscopy (Dr. Michael B. Robinson) ..................................................... 606

Undercooling Behaving of Immiscible Metal Alloys in the

Absence of Crucible Induced Nucleation (Dr. Michael B. Robinson) .................................................... 607

Undercooling Limits in Molten Semiconductors and Metals:

Structure and Superheating Dependencies (Dr. Frank G. Shi) ............................................................... 608

Crystal Nucleation, Hydrostatic Tension, and Diffusion in

Metal and Semiconductor Melts (Prof. Frans Spaepen) ....................................................................... 609

Micro- and Macro-Segregation in Alloys Solidifying

with Equiaxed Morphology (Prof. Doru M. Stefanescu) ........................................................................ 611

The Impaction, Spreading, and Solidification of Partially

Solidified Udercooled Droplets (Dr. Julian Szekely) ............................................................................... 613

Microporous Membrane and Foam Production by Solution Phase Separation: Effects of

Microgravity and Normal Gravity Environments on Evolution of Phase Separated

Structures (Dr. John M. Torkelson) ....................................................................................................... 615

Fundamentals q{ Mold-Free Casting Experimental

and Computational Studies (Prof. Gr6tar Tryggvason) ........................................................................ 617

Electromagnetic Field Effects in Semiconductor Crystal Growth (Dr. Martin P. Volz) ........................ 618

Coarsening in Solid-Liquid Mixtures (Prof. Peter W. Voorhees) ........................................................ 620

Containerless Liquid Phase Processing of Ceramic Materials (Dr. J. K. Richard Weber) .................... 622

BSO/BTO Identification of Gravity Related Effects on Crystal Growth,

Segregation, and Defect Formation (Prof. A.F. Witt) ............................................................................. 624

ATD

Microwave Furnace Development (Dr. Martin B. Barmatz) ................................................................. 626

Stereo Imaging Velocimetry (Dr. Mark Bethea) ..................................................................................... 628

Real-Time X-Ray Mieroscopy for Solidification Processing (Dr. Peter Curreri) .................................. 630

Microgravity Combustion Diagnostics (Paul S. Greenberg) ................................................................ 632

Small, Stable, Rugged Microgravity (Frank T. Harfley) ....................................................................... 636

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High Resolution Pressure Transducer and Controller (Dr. Ulf E. Israelsson) ...................................... 637

Surface Light Scattering Instruments (William V. Meyer) ................................................................... 639

Crystal Growth Instrumentation Development:

,4 Protein Crystal growth Studies Cell (Dr. Marc L. Pusey) .................................................................. 641

Multizone Furnace Control Algorithm Development (Bruce N. Rosenthai) ........................................ 643

High Resolution Termometry and Improved SQUID Readout (Dr. Peter Shirron) ............................... 645

Determination of Soot Volume Fraction

Using Laser-Induced Incandescence (Dr. Karen J. Weiland) ................................................................. 647

Multi-Color Holography (Mr. William K. Witherow) .......................................................................... 650

Ceramic Cartridges via Sintering and Vacuum Plasma Spray (Dr. Frank R. Zimmerman) ................ 651

III. BIBLIOGRAPHY ................................................................................................................................... 653

APPENDIX

Appendix A: Table of Acronyms .................................................................................................................... A-1

Appendix B: Guest investigator Index ........................................................................................................... B-1

Appendix C: Principal Investigator Index ..................................................................................................... C-1
[. MSAD Program Tasks & Bibliography -- FY1994 Objectives & Metrics

Io

Introduction

• Objectives and Focus for FY1994 ....................................... I-1

• Program Task Summary Data ............................................ I-5

I-1
l MSAD Program Tasks & Bibliography -- FY1994 Objectives & Metrics
OBJECTIVES AND FOCUS FOR FY1994

NASJ_'s Microgravity Science and Applications Division (MSAD) sponsors a program that seeks to

focus on the use of space as a laboratory by, undertaking the study of important physical, chemical, and

biochemical processes on orbit that cannot easily, be studied in the terrestrial gravity environment.

However, since flight opportunities are rare and flight hardware is very expensive, a strong grnundbased research program from which only the best experiments evolve is the keystone of the program.

The microgravity environment affords unique characteristics that allow the investigation of phenomena

and processes that are difficult or impossible to study on Earth. Significant reductions in critical

characteristics, such as buoyancy driven forces, convection, sedimentation, and hydrostatic pressures,

make it possible to isolate and control gravity-related phenomena and make measurements that have

significantly greater accuracy than can be achieved in normal gravity. Space flight gives scientists the

opportunity to study the fundamental states of physical matter--solids, liquids and gasses--and the

forces that affect those states. Because microgravity tends to allow the treatment of gravity as a variable,

research in microgravity leads to a greater fundamental understanding of the influence of gravity on the

world around us. With appropriate emphasis, the results of space experiments lead to both knowledge

and technological advances that have direct applications on Earth. Microgravity research also provides

the practical knowledge essential to the development of future space systems.

The Office of Life and Microgravity Sciences and Applications (OLMSA) is responsible for planning and

executing research stimulated by the Agency's broad scientific goals. OLMSA's Microgravity Science and

Applications Division (MSAD) is responsible for guiding and focusing a comprehensive program, and

currently manages its research and development tasks by dividing them into five major scientific

disciplines: benchmark science, biotechnology, combustion science, fluid physics, and materials science.

Fiscal year 1994 was an important year for microgravity science in general and for MSAD in particular.

Not only was the ground research program enhanced, several new investigators and research areas were

added to the program through maturation of experiments in a flight development phase. The on-orbit

research carried out in FY 1994 with two microgravity Space Shuttle missions is currently coming to

fruition as the results from these missions are gathered and evaluated. Scientific data from the second

United States Microgravity Payload (USMP-2), March 1994, and the second International Microgravity

Laboratory (IML-2), July 1994, provided valuable insight into each of the five discipline fields in FY 1994.

The processing and evaluation of these results have provided a solid basis for the planning of future

microgravity missions, such as USML-2 scheduled in September 1995, thus beginning the research cycle

anew.

This document, NASA Technical Memorandum 4677 [1995], The Microgravity Science and Applications

Program Tasks and Bibliography for Fiscal Year 1994 (October 1993 -September 1994), includes research

projects funded by the Office of Life and Microgravity Sciences and Applications, Microgravity Science

and Applications Division, during that year. This document is published annually and is sent to

scientists in the microgravity field, both foreign and domestic. The information provided in the Task

Book is used in reports to the NASA Associate Administrator, the Office of Management and Budget, and

to the United States Congress.

The Microgravity Science and Applications Division wishes to thank The Bionetics Corporation, and in

particular recognizing Mr. Bill Wilcox (task review process and publications manager) and Mr. Duke

Reiber (data system development) for their lead efforts in the development, compilation and publishing

of this report. Gratitude is also expressed for significant data processing support at the responsible

Centers for MSAD task management, recognizing: Dr. Mark Lysek and Angela Belcastro, JPL; Phyllis

Golden, JSC; Mary Malone, LeRC; and Richard McConnell, MSFC.

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[-3
I. MSADProgramTasks& Bibliography-- FY1994 Objectives & Metrics

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FY1994 PROGRAM RESEARCH TASK SUMMARY:

Overview Information and Statistics

Total Number of Principal Investigators: ........................................................................................................ 243

Total Number of Co-Investigators: ................................................................................................................... 254

Total Number of Bibliographic Listings: ........................................................................................................ 942

• Proceedings Papers: ........................................................................................................................ 146

• Journal Articles: ................................................................................................................................ 370

• NASA Tech Brief Articles: ................................................................................................................ 13

• Science/Technical Presentations: .................................................................................................. 389

• Books/Chapters: ................................................................................................................................. 24

Total Number of Patents Applied for or Awarded: ........................................................................................... 1

Number of Graduate Students Funded: .......................................................................................................... 434

Number of Graduate Degrees Granted

Based on MSAD-funded Research: .................................................................................................................. 125

Number of States with Funded Research (including District of Columbia): ............................................. 36

FY1993 Microgravity Science & Applications Budget: ............................................................. $188.0 Million

Microgravity Science & Applications Research Tasks and Types

Responsibilities by Center

Centers, Types of Research Ground Flight ATD Center Totals

Jet Propulsion Laboratory [ 29 7

3 39

Johnson Space Flight Center 10 0 0 10

Langley Research Center 3 2 0 5

Lewis Research Center 129 35 5 169

Marshall Space Flight Center 62 25 4 91

Goddard Space Flight Center 0 0 1 1

Research Task Totals 233 69 13 315
I[. MSAD Program Tasks -- FY1994 Research Disciplines

II.

Microgravity Science & Applications

Program Tasks for FY 1994

• Flight Research Tasks

Benchmark Science .............................................................. II-7

Biotechnology .................................................................... II-23

Combustion Science .......................................................... II-36

Fluid Physics ...................................................................... II-72

Materials Science ............................................................. II-112

• Ground Research Tasks

Benchmark Science .......................................................... II-159

Biotechnology .................................................................. II-198

Combustion Science ........................................................ II-250

Fluid Physics .................................................................... II-337

Materials Science ............................................................. II-483

• ATD

Advanced Technology Development ........................... II-626

II-5
II. MSAD Pro ram Tasks -- FY1994 Research Disciplines

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li-6
If. MSADProgramTasks-- Flight Research Discipline: Benchmark Science

I J o I a e I I I I! I I I o | I I t I I a I I o 11o | ! I ! I I I I I o I i ! ! I| ! t g | I | * i i i | I I o ! I tI I I I ! I i I I I I ! o I i io i i i i | i I I o I I| i io III I ! I I I o I I i! i o Iii I I o ii eI I III J I I I o I I o I I |! t I I I n | t I I ! i i I n i in i i ! i e i 1111; i o I I ! I I !I I I| I I! e I I ! ! i a o Iii I| I n i e I | t I ! I I io i! I i i i I ! i !Qo ii I I ! i I I _ I I I I io | I o o I I I i i III J I

Critical Dynamics in Microgravity

PRINCIPALINVESTIGATOR;Dr. Robert V. Duncan Sandia National Labs, and University of New Mexico

CO-INVESTIGATORS:

Talso C.P. Chui

U.E. Israelsson

Jet Propulsion Laboratory (JPL)

Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

The objective of the Critical Dynamics in Microgravity Experiment are as follows:

1. Measure the dependence of the normal state thermal conductivity (_) on the heat flux Q, and on the proximity

of the cell endplate:

- Nonlinear transport very close to T_.

- Q sets distance tYom criticality, as predicted by DRGT;

- Explore boundary suppression of fluctuations near criticality;

0.3 nW/cm 2 _<Q < 10 IXw/cm: with no convection in a 2 cm cell.

2. Measure the temperature profile very near, and through, the HeI-HelI interface:

- Measure ATx(Q) and explore "supercooled" HeI region as a function of small temperature and pressure changes

- Determine the boundary conditions on j, and possibly q0;

Determine if the interracial width (w) scales as predicted by DRGT and DS: w = wJqQ;

Measure the superfluid AT, hence Hell vorticity.

3. Search for hysteresis in the superfluid transition under heat flux:

- Up/down reproducibility;

Latent heat.

TASK DESCRIPTION:

A high-resolution, all-aluminum thermal conductivity cell containing a sample of ultra-high purity helium will be

employed for these measurements. The high resolution thermometers (HRT) developed for and used successfully on

the Lambda Point Experiment will also be used on DYNAMX to measure temperature gradients when a small heat

current is applied.

TASK SIGNIFICANCE:

The improvements to the HRT's developed for the CHeX mission will also be applied to the DYNAMX HRT's.

The all-aluminum construction will reduce the mass of the sample cell to reduce the degradation of the measurement

resolution caused by ionizing radiation in orbit.

PROGRESSDURING FY 1994:

The DYNA.MX project has worked to set up a cryoprobe for measuring the thermal conductivity of liquid helium

very near the lambda transition. This cryoprobe will be used to demonstrate the feasibility of the measurements that

were proposed for flight. Setting up the cryoprobe has involved: design and fabrication of a flight-like all-aluminum

experimental cell; fabrication and assembly of the parts of the cryoprobe; installation of major components like the

high resolution thermometers and the SQUIDs; and installation of the experimental cell with its heat flow paths

tailored to the requirements of a thermal model. Some details of the progress made on each of these tasks will be

provided below.

I1-7
InadditiontopreparationfthehardwarelortheIbasibilitydemonstrations, theDYNAMXteamhas"also taken

pains to communicate the aims of the experiment to the science community, and to establish channels of

communication to the nonscience community. The educational and outreach actions taken by DYNAMX team

members will also be delineated below.

Hardware Development

Two considerations have led to an all-aluminum experimental cell for DYNAMX: Aluminum has a smaller

cross-section lor interaction with ionizing radiation than has copper, so the added thermometer noise experienced on

the Lambda Point Expertrnent will be reduced significantly by using aluminum; and, the existence of both

high-conductivity and low-conductivity forms of "aluminum permits an all-welded construction with rings of

high-conductivity A! spaced by the low-conductivity alloy. Attaching HRTs to the high-conductivity rings then

allows the thermal profile to be measured "along the walls with a negligible traction of the heat flow through the

metal, while nearly all the heat flows through the near-critical helium; high-conductivity aluminum is used for

making these attachments, also. A rather detailed thermal model of the aluminum cell filled with helium near the

lambda transition has directed the placement of the high-conductivity rings at three points along the cell sidewall.

Two versions of the aluminum cell were built as the model was refined and as the range of parameters for testing

became better defined. A two-dimensional thermal model of the cell has been developed which takes into account

the radial heat flux created by the sidewall thermometer rings.

The cryoprobe for the ground-based measurements must provide the very stable thermal environment that allows

high-resolution measurements to be performed as the lambda point is approached. Three temperature-controlled

stages are placed between the cell and the 4 K liquid helium bath. To maintain a stable temperature at the cell, the

heat leak between stages must be small and predictable. Thus, a very low pressure must be established around the

platform to eliminate the vagaries of gaseous heat conduction between stages. With 42 vacuum seals and 65

electrical penetrations of the cold flange tot passing signals, pump lines, and fill lines into the experiment space,

preserving the vacuum integrity of this large volume presents a challenge. Each component of the DYNAMX

t.a'yoprobe has been successfully operated at low temperature during the past year.

The instrumentation tor DYNAMX has progressed well. The screened room in which the ground-based experiments

will be performed has been completed, and provides excellent protection from unwanted signals. Three high

resolution thermometers (HRTs) have been assembled and installed in the cryoprobe, and a lburth HRT is ready for

installation in the next phase of the experiment. Four SQUIDs are installed and operating well, so the HRTs can be

monitored with high resolution. A fifth SQUID feedthrough is also installed on the cold flange should monitoring

of a superconducting pressure transducer be required in the future. The lock-in amplifier, ratio transformer, and

temperature controller chain of instruments/'or controlling the temperature of the stages has been shown to provide

noise levels equivalent to less than 10.6K control uncertainty. The first implementation of the superconducting

pressure transducer was found in testing to have shorts in the pick-up coil, so a rebuild is under way, An innovative

DYNAMX-designed hydraulically-actuated valve for the sample cell has been fabricated and tested at liquid nitrogen

temperatures, and will be ready for installation when required tot filling the cell. This valve features a modular seat

which may be detached from the valve stem assembly without hot work. This ease of removal permits the valve tip

and the valve seat to be independently maintained and replaced.

Education and Outreach

The DYNAMX team members have been proactive in relating he objectives and potential benefits of the mission

to the public. By participating in open houses, fairs, university classes and compe0tions, the story of DYNAMX

has been delivered to thousands of citizens.

DYNAMX has been directly involved in several educational endeavors. One graduate student and a postdoctoral

fellow are continuing ' :l"education with DYNAMX support. The Principal Investigator taught a Physics

Department graduate seminar at the University of New Mexico that was attended for 10 weeks by 15-25 graduate

students and faculty members; the seminar described the basic principles of superfluidity and of the lambda

1I-8
transition, and demonstrated the uniqueness o1 the DYNAMX investigatmn of the transition under nonequilibrium

conditions. The PI ha,s also delivered two seminars and one reviled guest lecture at UNM to convev the intellectual

excitement of DYNAMX.

Another direct outreach involvement by DYNAMX was the stxmsorship of a competition to design a DYNAMX

patch at a community college m s i. Petersburg, Florida. The competition w_s advertised in the school newspaper to

the 25,()00-student commuuity of St. Petersburg Junior College, with descriptions of the experiment and its

objectives being part of the ad. 45 entries were received by the Art Deparunenl, and the five that they iudged

superior were forwarded to the DYNAMX team. The final selection w%s made at a meeting of the DYNAMX rerun

;it JPL m July. Award of a plaque will be made in November when the student designer visits the DYNAMX

facility at the University of New Mexico, and again itt December when the plaque will be presented at the Junior

College m a public ceremony.

The DYNAMX te_un h+cs also participated in presentations to the public at a JPL open house, and at two county

tmrs m the [,os Angeles area. These presentations generally include a DYNAMX story board explaining the

objectives and techniques of the DYNAMX experiment. Demonstrations of phase lr, msitions and of superlluid and

superconducting phenomena relate the experiment to everyday phenomena of phase ch_mges out of equilibrium.

Thousands of brochures describing DYNAMX as part of the program of low temperature microgravity

experimentation were provided to interested persons attending these events. Well over 10+000 citizens attended these

presentations according to estunates by the JPL Public Affairs Office.

Outreach to the scientific community has included severa.l more actions by the DYNAMX te_un. All members

participated m the pre-SCR review held th Washington in January.. There the DYNAMX objectives and experiment

plans were presented to a distinguished group of low temperature experimentalists and theorists comprising the JPL

Low Temperature Science Steering Group. The resulting enthusiastic endorsement ot the mission by the review

p_mel remvigorated the DYNAMX team; the paml's recommendations for actions to test the design of the

DYNAMX experiment cell will be followed in detail. The DYNAMX experiment w_ts also described to the wider

audience of 75 low temperature scientists attending the 1994 JPL Workshop on Low Temperature Research in

Microgravity. DYNAMX team members reached out to a very different group of scientists at the Twelfth

Symposium on Thermophysical Properties at Boulder in June. The PI presented a paper describing the DYNAMX

experiment, _md Ie_m-t members heard of many other studies of phase transitions, both Earth-bound and m orbit. The

P[ also attended a meeting of scientists studying order-disorder transitions, held at the University of California at

Santa Barbara in August, again describing the DYANMX experiment in a presentation. A! both of these meetings

the rerun members proliled from private discussions with many scientist,,;, both for relating the nonequilibrium

cxpermmnt to others, and learning ol diverse studies that could be relevant to the perlommnce of the DYNAMX

experiment and to rite interpretation of the results.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

BS Students: l) PROJECT IDENTIFICATION: 963-24-04-04

MS Students: 0 RESPONSIBLE CENTER: JPL

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Duncan, R.V_, Boyd. S., Moeur, W.. Robinson. S.. Akau. R.. and Gianoulakis. S. Critical dynamics in microgravity.

International Journal on Thermophysical Properties. in press. (1994).

Proceedings

Duncan, R.V., Boyd, S., Moeur, W., Robinson, S., Akau, R., and Gianoulakis. S. "Critical dynamics in microgravity."

Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.
II. MSAD Program Tasks -- Flight Research Discipline: Benchmark Science

Presentations

l)uncan, R.V. "Progress and review or DYNAMX," Pre-SCR Re','iew, Washington D.C.. January 1994.

Duncan. R.V.. Boyd. S., and Moeur. R. "Critical dynamics in microgravity." International Symposium on Order and

Disorder, Santa Barbara CA, 1994.

II-1 0
II. MSAD Program Tasks -- Flight Research Discipline: Benchmark Science

m l.l.lllll|ll È_l*_t_*tjj_È_!_**i_"I_i_*_I_1"_m"_j_È_*Ii1pH_i_"_È_Èi_i_"a"_mm"_"_mm"_Ii_i_j*_*_mi_*i_i**_ J lm.i;,H I*IIIH*III*IIIII*II.II.IOI.HH.I=_I=_.I._**=I_II_=I*

Satellite Test of the Equivalence Principle (STEP)

PRINCIPALINVESTIGATOR Prof. C. F. Everitt Stanford University

CO-INVESTIGATORS:

P. Worden Stantord University

TASK OBJECTIVE:

Tile objective of the Satellite Test of the Equivalence Principle (STEP) experiment is to investigate the foundation

ot gravitational theory, the equivalence of inertial and gravitational mass.

TASK DESCRIPTION:

The mission, now called Quick STEP, is a NASA led experiment with possible colloboration with the French

space agency. The Quick STEP mission is a descope M2 mission with the essential Equivalence Principle and

geodesy science intact. The overall cost has been reduced from approximately $600 m to $150 m.

TASK SIGNIFICANCE:

The STEP experiment may be thought of as a modem version of the experiment attributed to Galileo of dropping

two weights from the Leaning Tower of Pisa. Any difference in the ratio of gravitational to inertial mass causes a

corresponding difference in the rate of fall. The detection of a difference would substanti',.dly 'alter present theories of

relativity and gravitation.

PROGRESSDURING FY 1994:

Following the unsuccessful M2 study, the Satellite Test of the Equivalence Principle (STEP) proposal te_un

splintered into two independent efforts: an M3 proposal headed by the European elements of the original STEP

Study Team; and Quick STEP -- a JPL/Stanford effort emphasizing low cost and fast turn-around. Tbis section

outlines activities and achievements of the Quick STEP proposal team during fisc',:d year 1994.

In brief, the Quick STEP expertment is attempting to improve the current verification of the Equivalence Principle

(a postulate of general relativity) by six orders of magnitude. This is accomplished by measuring lhe differenual

displacement of mass pa_rs as they travel around the Earth on a drag compensating satellite. The masses are coaxr, d

cylindrical tubes suspended on superconducting magnetic bearings. Violations of the Equiv',dence Principle will

manifest as a differential displacement between the masses.

A complete Satellite redesign (except Payload), utilizing off-the-shelf technology wherever possible, wa.,, needed to

reduce the complexity and cost of the M2 approach. The Payload returned to its pre M2 six accelerometer

configuration. This redesign started with the definitmn of a new Satellite configuration capable of being launched on

an Orbital Science Taurus launch vehicle. The Taurus was selected for the strawman configuration because it

presented the most constraining yet still possible scenario. The strawman configuration was finalized in November.

Once established, the redesign turned toward three parallel activities: soliciting information about available

spacecraft buses; analyzing the Satellite thermalJmechanical design; and defining the Payload/Spacecraft electrical

interfaces. JPL lead the search/or an acceptable off-the- shelf spacecraft bus. A Request for Information (RFI) went

out in early December to a number of commercial aerospace companies soliciting input on a low cost, earth

orbiting bus meeting Quick STEPs power management, data handling, and communications needs. Several

responses came in below the allotted 25M cost. JPL "also lead the work on thermal and mechanical design analyses.

The mechanical analysis indicated a fairly conservative design with no major worries however, the thermal design

pointed to heat transfer into the dewar through the warm electronics interface as an area needing further study.

Finally, the del]nition of electrical interfaces and the overall system block diagram was a.joint JPL/Stanlord effort.

These activities culminated in the baseline Quick STEP design furnished at the JPL/OSSI Cost Review in May and,

in abridged format, at subsequent presentations to JPL senior management and to NASA Headquarters in June. Final

result: excluding reserves, Quick STEPs overall mission cost, including launch, was less than 140M -- a fraction of

!I-1 1
theoriginalM2costwithoutcompromising the primary scientific oNective.

Key technology development underway m FY94 include drag-free control studies, trapped flux work, helium motion

analysis, and initial development of accelerometer fabrication facilities. With the exception of the analysis and

design of an electrostatic helium confinement system done by Peter Mason at JPL, all technology development

activities were undertaken by Stanlord team members. Drag- tree control studies were the basis lor HaiPing Jins

doctoral thesis. These analyses tormed a comprehensive examination of the Quick STEP proportional thrust attitude

control scheme leading to the definition of subsystem pertorrnance requirements, baseline thruster configuration, and

the proposed Payload feedback control methodology. Rodney Torii, and Paul Worden began the fabrication and test

of a flux microscope and niobium test samples needed to characterize how environmental effects correlate to trapped

flux in superconductors. This work is essential to identify and understand factors pertinent to the superconducting

bearing design. Computer analyses of the liquid helium surlhce shape under the tidal effect,s of Earths gravity were

performed by John McCuan largely lot the GPB experiment but also with some relevance to Quick STEP. Helium

motion has been identified as a potential noise source for the EP measurement. Lastly, the design and assembly of

fabrication facilities needed for three dimensional photolithography used in the creation of the superconducting

bearings, began. Matthew Bye is overseeing the development of these tools; work will continue well into fiscal

1995.

Other items of note for fiscal 1994: Stanfords new labs; the Science Review; CNES activities; and the new direction

for fiscal 1995. Stanlord allocated some much needed lab space to the Quick STEP team at the start of the fiscal

year. This action represents a growing commiunent on the part of the university toward making the Quick STEP

proposal a reality. Some of the space requires substantial redesign and reconstruction to house the Quick STEP

fabrication labs (and much of FY94 was spent on exactly that); this reconstruction effort is expected to extend into

the middle of FY95. In the interim, the design, assembly and utilization of fabrication equipment will be

accommodated in the existing (though somewhat crowded) Quick STEP lab, A Quick STEP science review was held

in Washington in late February. The review board concluded that Quick STEP will: strengthen the foundation of

general relativity; provide drastic improvement on the bounds of new interactions between light elementary

particles; give substantial improvement in understanding the Earths gravity field. The board ",alsoagreed that Quick

STEP is the only realistic means to achieve such a large improvement in the accuracy of the verification of the

Equivalence Principle, and that Quick STEP is feasible with only minor improvement in the current technology.

Participation of the French Space Agency CNES has been (and still is) under consideration as a possible

risk/cost/technology sharing partner with NASA in a version of Quick STEP dubbed GeoSTEP. Details of such a

scenario have remained fairly fluid. In closing, Quick STEP suffered a bit of a set back at the end of lis "'cal1994

when its sponsor, Microgravity (Code U), elected to delay startup due to 1995 funding realities, While this delay is

disappointing, it has allowed Quick STEP time to focus on technology development and pursue a CNES and/or

other outside partnership.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/84 EXPIRATION: 9/94

BS Students: 1 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-07-10

MS Students: 0 MS Degrees: 0 RESPONSIBLE CENTER: JPL

PhD Students: 3 PhD Degrees: I

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Mason, P.V., Strayer. D.. Petrac. D., Gutt, G.. Warfield, K., Worden, P., and Torii, R. "The control of liquid Helium in

space by electrostatics for the satellite test of the equivalence principle experiment." Proceedings of the 39th Cryogenics

Engineering Conference. Advances in Cryogenic Engineering, vol 39.

Swartwout, M.A., and Worden. P.W. "Error analysis for the QuickSTEP." Proc. Seventh Marcel Grossman Meeting on

General Relativity, Stanford University, 1994.

Worden, P. "The Quick STEP instrument and science." Proceedings of the Seventh Marcel Grossman Meeting on General

Relativity, Stanford University, 1994.

11-1 2
II. MSADProgramTasks-- Flight Research Discipline: Benchmark Science

lie io .i i ii i l e|; ii i 1 i|1 ii i la ii I i i iml i i l llu i iHI ii i iii i.; .i.i.i. i m m|H 101|l i ll_Ul Hie01 IH i i;. i ill J l m. i i. i. i i o|l i_l u _. i u u t. i iii i i. i.ii iii i iii i ii_. Jl|llllu.i JlUllllllllmHlll I I|lJlm|l m ll H l|l m ll ||lmll I II ; I I01

Critical Dynamics of Fluids

PRINCIPAL INVESTIGATOR: Prof. Richard A. Ferrell University of Maryland

CO-INVESTIGATORS:

Dr. M. Moldover

Dr. R.A. Wilkinson

National Institute of Standards and Technology (NIST)

NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

This work has a three-part objective all relating to critical phase transitions in fluids. Part one confirms the

untested asymptotic limiting acoustic attenuation in simple liquid-vapor systems. The second part seeks to confirm

the fast dynamics of adiabatic heat transfer in compressible liquid-vapor critical systems using a near-term space

experiment. The third objective is to accelerate the theory of second sound attenuation at the lambda transition of

liquid 4He. The theory would allow for comparison to data from currently planned space expertments.

TASK DESCRIPTION:

The work involves three critical fluid investigations: l) ground-based definition of an acoustic attenuation in a pure

liquid-vapor system space experiment, 2) Principal Investigator activities for a last adiabatic thenn',d/density

relaxation space experiment to fly on IML-2 in 1994, and 3) theoretical work on second sound attenuation near the

lambda transition of 4He. Item 1 involves repeating the Garland & Thoen experunent to establish technique and

demonstrate that adiabatic heat transfer losses are detectable and predictable. That knowledge will be useful in

defining a space experiment that will not be hampered by the effect. It is the space experiment that would fulfill the

first objective.

Item 2 employs ESA's Critical Point Facility (CPF) with visu_ and interferometnc data. A heat pulsed wire and a

500v charged wire are used to sttmulate last transients. This activity also allows reflight of an IML-1 experiment

to study slow density relaxation with better geometric and thermal lxmndary conditions.

TASK SIGNIFICANCE:

Significance is based on the fundamental character of this work, all of which is driven by expenmenk_ only

possible in low-gravity. The 4He work is to bring current theory with experiments in process. The liquid-vapor

acoustics work is to probe one of the unverified predictions of older theory while properly accounting lor adiabatic

heat transfer loss mechanisms. The experiment on IML-2 also works toward the confirmation of the theory

describing adiabatic heat transfer in highly compressible, strongly property varying, critical fluids. One and two

dtmensional models are still qualitative in their description of experiments.

PROGRESSDURINGFY 1994:

I. Ambient Temperature

A. IML-2

1. TEQB: A method for projecting out the individual thermally relaxing modes of the fluid and thereby extract

their specific relaxation rates, has been developed by Dr. Hong, and is currently being applied to the flight data.

2. AFEQ - heat pulse: By means of a more complete theoretical treamaent, an error in the formula that has been

provided by the French group has been corrected. A comparison of the corrected formula with the flight data is

being tamed out by Dr. Greg Ztmmerli.

3. AFEQ - Voltage step: We have been able to derive an analytic expression for the electrostnctive effect as sccn

in the interferograms. The latter, by virtue of the microgravity environment, provide the l-trst experrmental evidence

for this effect. The post-flight delivery of photographic images will soon make possible their comparison with the

theoretically predicted fringe shifts.

_n_u_n_D_I_t_B_i__n_u_u_n_u_n_O_u_u_nu_n_n_l_

ii-1 3
II. MSADProgramTasks-- Flight Research Discipline: Benchmark Science

a611 t oi i i i i i ! J i i i oo| oai |t | | i ! | i | | i ! oi i || i it i i i i i ! ! t ! iii t | i i i ! i i t ! _i gQi io ii ! i i o| i ! i t ! i i ii i111 ! i i i | II | t I I I I aI I | I iI |! J III I | I I IO I I011 ! ! 0J | I I I OI I t I oI I I I 01! | I I a0| I t DIe I oI | t I I H I; t | | I ! t ! ! eIl; I I I. 0I! It! | I I 0tO Io Ilel Ill | _! O;I lea |l! OlIODOlII| leo;t|O00 I|o

B. Critical Ultrasonic Attenuation

1. Theory: An analytic treatment of the corrections to dynamic scaling has been reported at the NASA workshop

on low temperature physics (January 1994, Washington) and published in the proceedings. This theoretical work is

also applicable to the ambient temperature phase transitions of a one component fluid.

2. Experiment: The ongoing collaboration with Dr. Bob Kusner is starting to yield data on the damping of sound

waves by the effect of fast adiabatic equilibration. Visiting Professor Jayanta Bhattacharjee has determined the

theoretical crossover temperature at which the bulk contribution to the attenuation becomes equal to the adiabatic

surface contribution. He is in continuous contact during the course of this experiment, providing information on

the method of ploting the data so as to reveal and separate these two contributions, which have a quite different

physical origin,

C. Critical Viscosity

We have reported on extended investigation into the fea,sibility of carrying out earth based measurements of the

viscosity of a thin fluid layer closer to the critical point than has heretofore been possible.

D. Corrections to Dynamic Scaling

An analytic treatment of this problem, as a contribution to the "Festschrift" lbr K. Kawasaki has been reported.

II. Low Temperature

The method of images, combined with light scattering data, makes possible an "experimental prediction" for the

Che experiment of Lipa et al.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 12/92 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 963-24-0C-25

NASA CONTRACT NO,:NAG3-1395

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Ferrell, R.A. Singular correction to dynamic scaling for a fluid. Physica A, (1994)_

Ferrell, R.A. and Moldover, M.R. On the limitations imposed by the Earth's gravity on measurements of the critical

viscosity of a one-component fluid. Ann. der Phys., (1994).

Proceedings

Bhattacharjee, J.K. and Ferrell. R.A. "Corrections to dynamic scaling for the critical ultrasonic attenuation in a

one-component fluid." Proceedings of the NASA Workshop on Low-Temperature Physics. Washington, DC, January,

1994.

Ferrell. R.A. and Bhattacharjee, J.K. "An experimental prediction for CHeX." Proceedings of the NASA Workshop on

Low-Temperature Physics, Washington, DC, January, 1994.

i ii i I l ii { l Ill I I l Ill l Ill I el I Ol I I l Ill Ill l Ill I Is III Ill I II I ii I i I II I I ii i i I I I I I I I II I l I I I I I I l II I II II I l I I l I { I II l I I I Ill II l II l tl l lll ill Ill llll Ill I I I I Ill I I I l Ill I II II I Ill l II Ill l llllll Ill III l lllll Ill III Ill Oil el I III III Ill l lilt{ I 1lOll Ill Ill 1Silliest lille lille

lI-1 4
II. MSAD Program Tasks -- Flight Research Discipline: Benchmark Science

III I|I l lllllllll||ll fill l llll I|I I I$I|II IIII I|I II I II II l l|Jl 11111 l la Ill l l III I II I I II I l llll III l i| l l|lll Ill I III III III I II III I$I i III III I I l li I III I l lliillil|lllll|ll l lllllll|lllIll|lllillliliilli|llill I|III loll II I l lOll|lllll l ill ill fill l Olllllillnlnlll

Critical Fluid Light Scattering Experiment - ZENO

PRINCIPAL INVESTIGATOR:Prof. Robert W. Gammon University of Maryland

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this project is to measure the decay rates of critical density fluctuations in a simple fluid (xenon)

very near its liquid-vapor critical point using laser light scattering and photon correlation spectroscopy. Such

experiments are severely limited on 'Earth by the presence of gravity, which causes large density gradients in the

sample. The goal is to measure fluctuation decay rates with lpercent precision two decades closer to the critical

point than is possible on Earth, with a temperature resolution of +/- 3 microKelvin. This will require loading the

sample to 0.1percent of the critical density and taking data as close as 100 microKelvin to the critical temperature

(Tc = 289.72 K). The minimum mission ttme of 100 hours will allow a complete range of temperature points to

be covered, limited by the thermal response of the thermostat and correlation averaging times. Other technical

problems have been addressed such as multiple scattering and the effect of wetting layers.

TASK DESCRIPTION:

We have demonstrated the ability to avoid multiple scattering by using a thin sample (100 microns), and a

temperature history which can avoid wetting layers, a fast optical thermostat with microcomputer temperature

control and measurement, and accurate sample loading. Further, the important engineering tasks of mounting the

experiment to maintain alignment during flight have been cont-trmed.

The experiment entails measurement of the scattering intensity fluctuation decay rate at two angles lor each

temperature and simultaneously recording the scattering intensities and sample turbidity (from the transmission).

The analyzed intensity and turbidity data gives the correlation length at each temperature and locates the critical

temperature.

The fluctuation decay rate data set from these measurements will provide a severe test of the generalized

hydrodynamics theories of transport coefficients in the critical region. When compared to equivalent data from

binary liquid critical mixtures they will test the universality of critical dynamics.

TASK SIGNIFICANCE:

Such experiments are severely limited on Earth because gravity causes a large density gradient in the fluid due to the

divergence of the fluid compressibility as the critical temperature is approached. The data from this experiment will

provide a test of critical phenomena theories in a temperature re'aim that has not been adequately tested to date, due

to the limitations imposed by gravity. The data tests the current theory of crossover from assymptatic behavior

near Tc to pure background behavior t_ from To. Such a crossover theory is useful for predicting thermophysical

properties in supercritical fluid solvents

PROGRESSDURINGFY 1994:

Zeno apparatus and POCC team enjoyed a long and exciting flight on Columbia (STS-62), USMP-2 payload, in

March 1994. The experiment ran tor 13 days and 17 hours continuously, a probable record. The critical

temperature of our xenon sample was located in orbit on a homogenous sample to 50 microK. During its run we

collected 520 valid correiograms of the critical fluctuations at 35 temperatures spanning 600 mK to -100 microK

from To. This covered the prtmary data range of 100 mK to 100 microK with three points per decade and added

points above 100 mK in a linear steps through Tc. The average decay rate was determined from fitting all the

correlograms at each temperature and gave the planned precision of lpercent.

I I I I I III I II I I I I I I I]I I# Ill I I | I I |I I ! I I I I I I I I I I I I I I I I I I I II I I I II l ! I I I I ! I I I I I I I I I I I I I I I I I I I I I I I ! I I I I I I I I II I III I II I I I I II I I I I I I II I II I I I I I I I ! I I I I I ! I I I I I I I I I I II I I I ! I l I, I, I I I ! I I I I I I I I II I I I II I I I I I I I I I I I I I I II I I I I I I I, I ! l I ! I I I I I I I II I I I I I I I I ! I I I I I I I I I II I II I I I II

II-1 5
The pertorrnance of the radiation control of the Optics Module temperature was excellent and we were able to

optimize it because of the long period of holding a single Shuttle attitude. The temperature control of the sample

met our stringent requirements with margin: we routinely had a less than 3 microK rms noise in three hours on our

temperature readings.

We have been working toward understanding of our experiment in two ways since the mission. One has been

carefully organizing the 200 Mbytes of data with some structure and indexes. Improvements were made in the speed

and buffering of our ground software so that we could look at large blocks of the archival data. We have corrected an

error in our analysis of the back scattering correiograms and are now approaching critical comparisons with available

data such as the Berg/Moldover viscosity data set. The second major activity was to do the Tc search of our sample

in extremely stable, </+ 10 microK/month and to confirm that the sample had survived shipping, storage, and

orbital flight, without losing more tl an 0.1percent of its gas. The laser beam alignment was maintained through

and after the flight.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 12/88 EXPIRATION: 2/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-50-0C-25

MS Students: 0 MS Degrees: 0 NASA CONTRACT NO.NAS3-25370

PhD Students: 5 PhD Degrees: _ RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Li. W.B., Serge, P.N., Gammon, R.W., and Sengers, J.V. Small-angle Rayleigh scattering from nonequilibrium

fluctuations in liquids and liquid mixtures. Physica A, Vol. 204, 399 (1994).

Li, W.B., Sergwe, P.N., Gammon, R.W., and Sengers, J.V. Determination of the temperature and concentration

dependence of the refractive index of a liquid mixture. J. Chem. Phys., Vol. 101, 5058 (1994).

Presentations

Briggs M.E., and Gammon R.W. "Photothermal deflection in a supercritical fluid." Paper at the Conference on Optical

Characterization of Coatings and Substrates, Symposium on Optical Interface Coatings, Grenoble. France. June 6-10,

1994.

Gammon, R.W.. Shaumeyer, J.N.. Boulari, H., Briggs, M.E., and Gent, D.A. "Zeno: Critical fluid light scattering from

xenon in microgravity." Invited talk at the 12th Symposium on Thermophysical Properties, Boulder, CO. June 19-24,

1994.

I a o I I IIll a I I a I o I e I I I I I I o eI a I| I I|ll | II Ilia I II l I OI I e l ii ii i i { i i i i e i i i ie o I I I I i l i i i 1111111 el I lie | |o I | o oI I el i i i I o i i o i| I ii I I I o i | e I Ie o| i I I I I i a i i i i ii i ii i I i i i o a | i a o ii i ii I | | o | | a |! a ii a i o i l ! i i o | aii i o| i i i | a i i i i i i i o ei i i i i i I i i i i i i e i oi ii i i i i I i i o io o i o i i i i a ia e i i i i i l

II-I 6
[I. MSADProgramTasks-- Flight Research Discipline: Benchmark Science

ffl'at Capacity Measurements Near the Lambda Point of Helium

PRINCIPALINVESTIGATOR:Prof. John A. Lipa Stanlbrd University

Co- INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

Central to condensed-matter physics is the phenomenon ol second-order phase transitions. These come about when

a wide class of interactive terms is added to the stmple ideal gas picture of matter. To understand condensed matter

in general, it is necessary to address the phase transition issue, since phase transitions are involved in nearly all

interesting effects observed. Our goal is to perform the most stringent test currently feasible of the present theory

of second- order phase transitions in the asymptotic limit as the transition is approached. To do this we will

measure the heat capacity of helium very close to its lambda transition at 2.177 K.

TASK DESCRIPTION:

To perform the heat-capacity measurements, two mare requirements must be met: first, we must have sutticient

temperature resolution to establish the temperature scale, and second, we need to control the energy input to the

sample to determine its heat capacity.

To these ends we have been developing a new high-resolution thermometer and an advanced, multilayer thermal

control system. The thermometer makes use of superconducting technology to achieve a resolution of about

3x 10 "_ K in a 1-Hz bandwidth, and the thermal control system can achieve a power resolution approaching 10..2 W.

TASK SIGNIFICANCE:

These two systems give us the capability to make measurements to the limiL_ imposed by the Space Shuttle

environment. A third requirement is to achieve an operating temperature near the lambda point. To do this we

make use of the superfluid helium research facility previously flown on Spacelab-2 by JPL.

PROGRESS DURING FY 1994:

For the past 50 years scientists have been developing theories of condensed materials, the form of matter we are

most familiar with in everyday life. These theories have had great difficulty predicting phase transitions, especially

a type called co-operative transitions. Since these transitions occur in practically all forms of matter, it was a major

challenge tor the theories to predict them accurately. In the early '70s K. Wilson developed a new theory, based on

ideas from high energy physics. This appeared to work very, well and he was awarded the Nobel Prize for the work.

The Lanlbda Point Experiment is the latest and by far the most precise test of this theory. By making

measurements in microgravity it probes a transition 100 times more closely than is possible on the ground

allowing substantially improved tests of the theory. The main test derived from the experiment is to compare the

predicted and observed values of the exponent characterizing the divergence of the heat capacity at the transition. A

second, somewhat less direct test of the theory can be made. The advantage of this test, however, is that the

theoretical prediction is exact. To perform the test we must combine the heat capacity result with that fi-om another

experiment, a measurement of the behavior of the superfluid density near the transition. Theory states that the

exponents from the two experiments must obey an exact relationship, called a scaling law. Fortunately, new high

accuracy results have recently been obtained in this area at Stantbrd. Additional results from the expertment are in

the area of the thermal response of the helium just above the transition. Here, measurements can be compared with

the expected behavior of the thermal conductivity, based on predictions of dynamic theories of phase transitions.

This year marked the successful completion of the LPE program. All effort during the year was directed to data

analysis. Numerous small effects that perturb the results were characterized and corrections applied. Unfortunately,

11-1 7
this process has yet to be completed itt a fully satistactory manner. The analysis is continuing on a time available

basis and is expected to be complete by the end of '94. Preliminary results have been obtained in 'all areas. The

v',due Iound for the exponent. -.0128 +.0004, is within the current theoretical range, and five tunes more accurate

than before. The test of die theory is weakened by the much l_ger uncertainties now existing in the theoretical

estimates. Their uncertainties are now about 15 times greater than that in the experiment. Thus, our result will

stand for some time as a benchmark for comparison with new theoretical calculations in this area. Using the

scaling law and the latest Stanford superfluid density exponent, theory predicts that the heat capacity exponent

should be: -.0105+.00024. This is off the observed value by about five standard deviations. The probability of this

being a statistical accident is less than 0.1%. However, we cannot take the discrepancy too seriously just yet,

because of the potential for systematic errors in the results. This is part of the tea.son we are proceeding very

cautiously in the analysis of the flight data. The tentative result of the analysis is therefore that the theory

continues to work even in the extreme conditions of the flight experiment. This gives us a great deal of confidence

that Wilson's theory, completely solves the phase transition problem. Other aspects of the theory, predicting the

properties of condensed matter in general, need to be examined on their merits, but it is clear that the underlying

principles are capable of explaining a very wide range of properties of ordinary matter.

The thermal conductivity of helium was also measured in the region just above the lambda point, where it varies

very rapidly with temperature. These measurements extend the testing of phase transition dynamics by about an

order of magnitude in temperature resolution. Reasonable agreement was 'also obtained in this area.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: O

MS Students: 2 MS Degrees: 0

PhD Students: 3 PhD Degrees: 1

TASK INITIATION: 10/86 EXPIRATION: 12/93

PROJECT IDENTIFICATION: 963-24-04-05

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Adriaans, M.J., Swanson. D.R.. and Lipa, J.A. The velocity of 2nd sound near the ]ambda-transition in superfluid He-4.

Physica B, vol 194, 733-734 (1994).

Chui. T.C.P.. Swanson. D.R.. Adriaans. M.J.. Nissen. J.A.. and Lipa. J.A. Temperature noise measurements in the

cannonical ensomble. Physica B. vol 194. 23-24 (1994).

Lipa. J.A.. Swanson. D.R.. Nissen. J.A.. and Chui, T.C.P.

the lambda point. Physica B. w)l 197. 239-248 11994).

Lipa, J.A.. Swanson. D.R., Nissen, J.A.. and Chui. T.C.P.

34, no 5. 341-347 (1994).

Heat capacity and thermal relaxation of bulk helium very near

Lambda-point experiment in microgravity. Cyrogenics, vol

Proceedings

Lipa, J.A., Adriaans. M.J., and DiPirro. M.J. "Mission concept for a new test of the universality hypothesis using order

parameter measurements below the lambda transition of helium." Proceedings of the NASA/JPL 1994 Microgravity Low

Temperature Physics Workshop.

Lipa, J.A., Swanson. D.R., and Nissen, J.A. "Heat capacity and thermal relaxation of bulk helium very near the lambda

point." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

I|_|_I!___!_|III_!____III_|_!||Ie||I_I_e___!I|||!|!!e__*_______I___|____II*Ill!I_|!_*I__Il_I___!_II*I!eI!_II_!I|_II_II_____I__I_|I||___Il_|_|_Ill_Ie!I_e___!__|___II_________Im_||_I_|e____|*I_|I||I_Ill__|_I_II||_I__I|__|I_|_____e|_|||||_||_||I!|

II-1 8
Confined Helium Experiment (CHeX)

PRINCIPALINVESTIGATOR:Prof. John A. Lipa Stantord University

CO-INVESTIGATORS:

T.C.P. Chui

U.E. Israelsson

F.M. Gasparini

Jet Propulsion Laboratory (JPL)

Jet Propulsion Laboratory (JPL)

State University of New York, Buffalo

TASK OBJECTIVE:

Of significant current interest in the field of condensed matter is the study of crossover behavior as a bulk system if

confined more and more tightly in one or more dimensions. Crossover occurs when the effect of the boundaries is

significant but not dominant. An ideal way to explore this effect is to perform measuremencs on films of ever

decreasing thickness until the lower dimensional behavior is dominant. Unfortunately, it is not possible to vary the

film thickness in most cases without totally changing the sample= making it difficult to keep track of intnnsic

changes m the parameters. Near the lambda transition of helium the correlation length diverges, magnifying the

effects of the confinement while simultaneously decreasing the importance of substrates. This situation gives us a

unique tool to look at a diverse set of conditions in a controlled way, opening a new window on the general

question of finite size phenomena in condensed matter systems. For example, at 0.1C below the transition, the

correlation length is on the order of a few Angstroms, whereas 10"gc below the transition the correlation length is

about 0.1 mm. If we can access the temperature region very close to the transition, we will have--for the first

time--a t]nite size system with a truly macroscopic length scale, allowing exceptional control of the effects of

boundaries. This situation appears to be absolutely unique in condensed matter systems. The Confined Helium

Experiment should lead to dramatically improved tests of the theory of finite size efteels.

TASK DESCRIPTION:

We plan to measure the heat capacity of helium confined between closely spaced parallel plates and compare the

results with the bulk heat capacity data obtained on the Lambda Point Experiment (LPE). The relationship between

the two data sets is predicted by theories of confinement. Most of the LPE flight hardware will be reused to

perform the required measurements.

TASK SIGNIFICANCE;

The Confined Helium Experiment should provide a much improved test of the theory, of confinement a_d may

provide a finn basis for its extension to other properties of confined materials.

PROGRESSDURINGFY 1994:

In the past year most of the effort has been centered on developing the confinement stack for the helium, tabncating

and testing of flight prototype thermometers, and setting up the environment for flight code development. Also, at

JPL, the flight cryostat performance has been enhanced to better match the nee&s of the mission.

The spacing in the confinement stack was changed from 100 to 50 microns on recommendation of the science

review panel, to allow improved measurement of any potential deviations from theoretical predictions. This

precipitated a significant effort to fabricate the new geometry using silicon wafer etching technology. This has been

successful on a sample basis, and testing lor flight production is currently in progress. In parallel, a 100 micron

stack was subjected to a qualification shake at low temperatures with poor results. This led us to perlorm a major

redesign of the stack to c'alortmeter fixturing, to mintmize the streses on the silicon. A model of the new design was

recendy shaken sucessfully.
Prototype thermometers were deveh)ped to give improved performance over the LPE devices. The bandwidth of the

devices was increased to 10 Hz to minimize the effect of char,,ed,_ particle radiation. This change also had the effect

of reducing the random noise of the devices in a 1 Hz bandwidth. Their resolution was found to be about 90

pico-Kelvins with 1 second of integration, a factor of 3 improvement over LPE. For CHEX, these devices will

probably become limited by acceleration noise on the Shuttle. Since the CHEX equirement was set close to the

LPE observed noise, we should have margin in this area.

For flight code development, we have set up a clone of the flight electronics and connected it to a prototype

instrument, and an engineering model computer. This system is now operational and code work has started. Most

of the high level code will be ported from LPE, but the lower levels will be built from scratch. Two of the major

changes from LPE are 100 Hz sampling capability and 1000 byte telemetry packages. Both these features have been

demons_ated.

The flight cryostat was modified to reduce the heat leak into the helium tank, extending its lifetime. Also the

transfer procedure was upgraded to reduce the thermal transients on the refills, allowing a lower level to be reached

without impacting the experiment. This latter improvement alleviates problems with cryostat mmnenance on the

pad. A 12 day hold time in orbit has been achieved, comtbrtably accoimnodating the science objectives.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Stutlents: 1

TASK INITIATION: 12/92 EXPIRATION: 12/97

PROJECT IDENTIFICATION: 963-24-04-02

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

.Iouruals

Coleman. M. and Lipa, J.A, Heat capacity of helium confined to 8 micron cylinders near the lambda point. Phys. Rev.

Lett,, in press, (Decetnber 1994}.

Nissen, J.A., Chui, T.C.P., and Lipa, J.A. The specific-heat of confined helium near the lambda-point. Physics B. w_l

194, 615-616 (1994).

Nissen, J.A.. Chui, TC.P., and Lipa, J.A. The specific-heat of confined helium near the lambda point. J. l,ow Temp.

Phys., vol 92, 353-366 (1993).

Swanson. 1).R., Nissan, J.A.. Chui. T.C.P.. Williamson, P.R., and Lipa, J.A. Optimization and performance of

high-resolution thermometers in low-earth orbit. Physica I3, vol 194, 25-26 (1994).

Proceedings

Nissen, J.A., Swanson, D.R., Qin, X. Salvino. D., Lipa, J.A.. Chui. T.C.P., lsraelsson, U., and Oasparini. F.M. "qqm

confined helium experimentin microgravity." Proceedings ofthe NASA_PL 1994 Microgravity Low Tcmperature Physics

Workshop.

11-20
II. MSAD Program Tasks -- Flight Research Discipline: Benchmark Science

Critical Fluid Thermal Equilibrium Dynamics

PRINCIPALINVESTIGATOR:Dr. R. A. Wilkinson NASA Lewis Research Center (LeRC)

CO-INVESTIGATORS:

Dr. R. Berg

Dr. M. Moldover

Prof. R. Gammon

Prof. J. Straub

National Institute of Standards and Technology (NIST)

National Institute of Standards and Technology (NIST)

University of Maryland

Technical University of Munich, DE

TASK OBJECTIVE:

The objective of this study is to examine the thermal and density relaxation with time, atier a temperature

perturbation, of SF_ near its liquid-vapor critical point, in a low-gravity environment.

TASK DESCRIPTION:

An SF_ sample was observed using interferometry, visualization, and transmission using ESA's Critical Point

Facility on IML-1. One of the scientific objectives was to observe the following: large-phase domain

homogenization with and without stirring of the fluid; time evolution of heat and mass transfer alter a temperature

step is applied; phase evolution and configuration after transition from one-phase equilibrium to a two-phase state;

and the effects of stirring on a two-pha._e low-gravity configuration. A second obiective was to quantity the mass

and thermal tune constant of a one-phase system under logarithmic temperature steps.

TASK SIGNIFICANCE;

Critical-point experiments generally depend on achieving thermal equilibrium to within a specified tolerance and on

knowing how phases develop or disappear. Data tiom this experiment will be used to determine the practical

time-scale needed to execute meaningful critical fluid space experiments. A second use of the data was to

characterize the location and growth dynamics of density or phase domains within a critical sample with vanishing

surface tension.

PROGRESSDURING FY 1994:

The funding for this activity expired at the beginning of the FY94 liscal year. Ilowever, work continued. A draft

preprint of the low-gravity results was completed in October 1993. Key observation indicated that the observed

time constants of the slowest relaxation modes were factors of two and three larger than predicted, with an unusual

amount of scatter in the data. Due to the difficulty explaining the results and concerns that the experiment was

misleading, the paper has not been submitted for publication. A reflight in July 1994 on [ML-2 shows better

results with more ideal thermal boun 'dary conditions.

E'_-gravity data from the IML-I apparatus was "also analyzed during the fiscal year. It showed an unsystematic

height dependence for the relaxation time constants that only increased the scatter seen from low-g data. The

analysis clarified that when the gravity vector is along the cylindrical axis of our thin disk cell, it is a poor

configuration to compare with low gravity. One had to be roughly 10 mK from Tc to get fluid time constants

longer than the thermostat ik_elt; and then the time constants were nearly an order of magnitude smaller than in

low-g. When the gravity vector was along a diameter of our disk shaped cell, the time constants were roughly like

those in low gravity.

This work has merged into the Ferrell Adiabatic Fast Equilibration experiment activity on IML-2.

I1--2 1
11. MSAD Program Tasks -- Flight Research Discip|ine: Benchmark Science

i i i o |t| | o | | o | | Io Bio o 11s Is i ¢o s I |o |i | | o I o | I i o _ iiI I o i o n, n in i I o i n i i I I o I I o II I _ s ! o i | III | i I _ o! ¢ I I i I ! o I I | oi | ii I | i n | I _ _ oo o i | o i i o n i o _ a o oI o o i, J | _ o, n I o |, ! s t e | I i, I I | iI !, I i o i I i | 11 | i I * | I o o i ! o i o | o | i o | I I o | oo bIo I 1111 ¢ n !s ! Io I o | ! o, o i ! 11o | _ I o o ! |o | H _o |1 o n n * I _ ¢ I | o I

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/89 EXPIRATION: 9/93

PROJECT IDENTIFICATION: 963-24-05-06

RESPONSIBLECENTER: LeRC

I oIi |sI os! Ill Illu I_OI | Il | |I I | o! I OUii I ! nlS! onI qO| o| I ulOS1o|ila I oaIi | OO| _! Ist !I I! III uI | I ! ! OOIIIq III ! oSI iIr_! III !Is II O| ! OI ! | I I OI! O| I oI I la! O! I I I| O! II! SI ! OI o! aOn_oonnO! DO! OI ! OI I | OI IOo! I oooU! O| oSoO |oIn| _I I I I oI I IoI illns ! | ! ! oni I !I n_I | oo! os q_|o! uo_nn_o| I uI Io | aa_oI nl! ! oI I Ill ! nil I I nI

1I-2 2
II. MSAD Program Tasks -- Flight Research Discipline: Biotechnology

_H_IiI_i_i_i_ii"_"_o_o_o_;_Ha_:_u_i_oi_ii_"_oHol_"_H_iaIli"_iof_In_"_i_H_ jog_1_l_I_I_iii_i_a_iI_i_i_ii_i_ii_i|_|H_i_|_ii_ii_i_i_|lioii_a_u|u|_Di_i_|_H_||bj_bin_i_ii

Protein Crystal Growth Vapor-Dtffusion Flight Hardware and Facility

PRINCIPALINVESTIGATOR:Dr. Daniel C. C_trter NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

J. Ho (X. He)

T. Miller

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The major objectives of this research are to provide a user-friendly interface between ground-based and flight protein

crystal growth hardware, increased (common) availability of flight hardware, elimination of late access requirement,

and individual loading by the principal investigator.

TASK DESCRIPTION:

Initially, these experiments will be conducted with a small hand-held unit using human serum "albumin.

Subsequent tests will involve the growth of Fab 3D6, a human anti-HIV antibody. When the necessary, tests and

procedures have been completed with the hand-held unit. facility flight hardware will be constructed. The

microgravity expertments will be conducted in two stages. In the first stage, the hand-held unit will be flown to

test the overall concept, refine the hardware if necessary, and establish protocols for later scale-ups with multi-user

hardware. The design would then be configured to accomodate several trays and interface directly with the existing

refrigerator/incubator module (R/IM) and thermal environment system (TES) temperature control hardwares without

modification. In addition, a new plastic tray will be developed to provide additional advantages in optical, storage,

and hardware inter/aces with a potential increase in the number of experiments in each tray assembly (VDT). In the

early periods of the second stage, the facility hardware will utilize cryogenics only for improvements in experiment

pre-loading elficiency. In order to proceed with the cryogenic aspects of the second stage, a sub-zero freezer will

have to be developed. When flight freezers are utilized, the hardware is left in the activation configuration, and

protein crystallization proceeds ",dter the experiments are withdrawn from the freezer and placed in the temperature

control units.

TASK SIGNIFICANCE:

This research is concerned with the development of a protein crystal growth system for microgravity which provides

for rapid, convenient access to the microgravity environment and a greater number of samples, and eliminates

numerous problems associated with logistics and handling of the current flight hardware.

PROGRESSDURING FY 1994:

1. Over the course of the past year the Hand-Held Protein Crystallization Apparatus for Microgravity (HH-PCAM)

hardware was constructed, flight approved, and tested as a mid-deck hand-held expertment during STS-62. The flight

contained tour HH-PCAMs with a total capacity of 96 individual vapor diffusion protein crystallization chambers.

The operation and crystallization experiments performed flawlessly. Some of the crystals grown were of the highest

quality.

2. Based on the success of HH-PCAM as the proof of concept, facility hardware has been designed, and a prototype

contructed and tested. Complete flight drawings have been approved and 18 flight units of the facility hardware

constructed. The hardware, with a total of 378 individual expertmetns, has unprecedented capacity within the STES.

Additionally, it has been designed to/unction in a cryogenic capacity within JSC flight dewars, as well as provide a

flexible glove box inter/ace. The cylindrical PCAMs are manifested on three upcoming flights in 1995.

3. Procedures have been established to solicit and review crystallization experiments proposed lor the facility. A

co-investigator group has been established.

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11-23
IL MSAD Program Tasks -- Flight Research Discipline: Biotechnology

iiIlll¢ll*ll!ll*l*l|ll*il|lllll!*l!|lll01|ll,llll!*ll!, J!*llllllllllll|ll_!**ll0!lll J|llll|lJt!l|*l| J!*!l|il!ll!lll!l|| Jllil _!!|_*!|_i!_*_!|_1!_*!!**!_|_||_*|_|_!*I!|_!i_!!_|!!!|_!!_|H_H_!_!*H*_!_**|*||_|_

4. Another area of the flight experiment series was initiated as a request for tlight experiments which could take

advantage of the longer duration, early MIR flights. The Dialysis Crystallization Apparatus for Microgravity was

proposed and developed. The hardware is specifically designed to take 'advantage of the diffusive properties of liquids

at zero-g to control inexpensively and effectively the critical approach to supersaturation. The new hardware has

numerous "advantages such as not requiring activation or deactivation by the crew. Current design "allows 81 large

volume diffusion cells shich can accommodate a variety of crystallization techniques and worlc_ equally well for

small molecule and protein crystallization. The hardware has great potential for a variety of ground-based

applications as well.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 5/93 EXPIRATION: 11/97

PROJECT IDENTIFICATION: 963-23-08-08

NASA CONTRACT No.: In-house

RESPONSIBLECENTER: MSFC

11--24
II. MSAD Program Tasks -- Hight Research Discipline: Biotechnology

Advanced High Brilliance X-Ray Source

PRINCIPAL INVESTIGATOR:Dr. Daniel C. Carter NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

W. Gibson

M. Kumakhov

J. Ho (X. He)

State University of New York, Albany

I.V. Kurchatov Institute of Atomic Energy

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The primary objective of this research is to produce the first x-ray generator and Kmnakhov lens system optimized

in design tor 8.0 KeV x-rays.

TASK DESCRIPTION:

The x-ray unit will be integrated with existing x-ray diffraction equipment at Marshall Space Flight Center to

produce a diffraction facility with the most advanced laboratory x-ray source for application in crystallography in the

world. The approach to complete the task will be to produce intense small cross section parallel x-ray beams for

structurM analysis using third-generation Kumakhov optics.

TASK SIGNIFICANCE:

Protein crystallography is currently the most powerful method for the determination of the three-dimensional

structure of proteins and other macromolecules. This method usually requires crystals which are relatively large in

size and which possess a reasonably high degree of internal order. This research is concerned with the development

of an extremely bright x-my source for application in the evaluation and determination of the atomic structure of

crystalline matter from both ground-based and current flight experiment activities.

PROGRESSDURING FY 1994:

The prototype x-ray lenses in this study are close packed capillary tubes with changing cross section "along their

entire length from input to output. An arrnagement of tubes with the appropriate shape can collect and guide x-rays

from a point source to produce an intense parallel beam.

1. Stage I optic completed: The l-trst in a series of three x-ray concentrators has been completed and tested.

Although not optimum in terms of transmission efficiency and focal length, this prototype optic already shows an

excellent intensity increase of a factor of 34.

2. High flux microfocus source acquired and tested: A unique microfocus x-ray source was obtained from the

Russian collaborators and was tested at the Center ti3r X-ray Optics at SUNY, Albany. The measured source

intensity was 30 watts at Cu Ka (8.04 KeV) in a 5 bun spot which is at least six times greater than is available in

stan "dard commercial sources.

3. Manufacturing capability upgraded: A computerized capillary drawing fixture has been installed, replacing

manual operation, and modelling has progressed to the point that actual x-ray performance can be accurately

predicted. Simulation shows that an optimum shape would give enhancement of about 650 over circular

collimation.

I i II I I I I i I i i i i i iii I I I I I I I I I I I I II I i i i i I II I II II Ii I | I I I I I I I I I I | i i I II I I I I I I I I ! II II I I I I II i I II I II I I I I I I I I Ii iii i I I III I III I I I II I II I I i II I I I ii I i iI i i I i ii i I I I i i I I I II II I ! I I I I II I I I II I ii I i i I I I I I I I I III I I II I I I I I I I I i I iI i i I I I i I I I II I i I I Ii I I I i I I I II i I illll I I I I I I i i i i

11-2 5
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 4/93 EXPIRATION: 3/96

PROJECT IDENTIFICATION: 963-40-20-30

NASA CONTRACT NO.: In-house

RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Ullrich. J.B.. Gibson, W.M.. Gubarev. M.V,, and MacDonald. C.A. Potential for concentration of synchrotron beams

with capillary optics. Nuclear Instruments and Methods. ','_1. A347, 401-406 (1994).

Ullrich, J.B.. Kovanstev, V.. and MacDonald, C,A. Measurements of polycapillary X-ray optics. J. Appl. Phys., vol, 74,

5933-5939 (1993).

Proceedings

Gibson. W.M., and MacDonald. C.A. "Polycapillary Kumakhov optics: a status report." X-Ray and UV Detectors, SPIE

Proc., 2278. 156-167 (1994).

MacDonald. C.A., Abreu, C.C.. Budkov. S.. Chen, H.. Fu, X.. Gibson. W.M., Kardiawarman. Karnaukhov, A.. Ponomarev.

I.Y., Rath, B.K.. Ullrich. J.B., Vartanian. M., and Xiao, QF. "Quantitative measurements of the performance of capillary

X-ray optics." Multilayer and Grazing Incidence X-ray/EUV Optics II. SPIE Proc., 2011 (1993).

Ullrich, J.B., Ponomarev. I,Y., Gubarev. M.V., Gao, N., Xiao, Q.F., and Gibson, W.M. "Development of monolithic

capillary optics for X-ray diffraction applications." X-Ray and UV Detectors. SPIE Proc., 2278, 148-155 (1994).

Wentink, R,. Carbone. J., Aloise. D.. Gibson. W.M., MacDonald, C.A.. Hanley, Q.E., Fields, R.E., and Denton, M.B.

"Charge injection device tCID) technology: an imaging solution for photon and particle imaging applications." SPIE

Proc.. 2279 (1994/.

11-2 6
Protein Crystal Growth in Microgravity

PRINCIPALINVESTIGATOR: Dr. Lawrence J. DeLucas University of Alabama, Birmingham

CO-INVESTIGATORS:

Noted Guest Investigators See List, Appendix B

TASK OBJECTIVE:

The objectives of this research are: to develop improved protein crystal growth flight hardware to produce larger,

high quality protein crystals in microgravity for use in the determination of protein molecular structures for

applications in medicine, drug design, agriculture, and the biological sciences; and to understand the

dynamics/process of protein crystal growth.

TASK DESCRIPTION:

A breadboard system will be developed that utilizes light scattering to detect the onset of crystal nucleation. This

optical monitoring system will be developed for both vapor diffusion and temperature-induced crystallization

techniques. This hardware will be used to grow crystals with dynamic control of the appropriate crystallization

parameter (i.e., temperature or vapor diffusion). The crystals will be evaluated microscopically and, from this

evaluation, the best crystals will be used for x-ray data collection using the facilities available within the CMC.

The data will then be compared with the best data obtained from ground-based crystals, and an evaluation of the

usefulness of these dynamically-controlled systems will be made.

TASK SIGNIFICANCE:

Larger, high quality protein crystals may be used in molecular structure determinations for applications in medicine,

drug design, agriculture, and the biological sciences.

PROGRESSDURINGFY 1994:

• DCPCG-Vapor Diffusion

Automated dynamic control of protein crystal growth using controlled vapor diffusion has been achieved. Two

primary devices have been constructed to prove the feasibility and utility of this approach. The main features of the

In'st device include the ability to: evaporate water from a growth solution at virtually any rate, quantitatively

monitor the water evaporated over time, perform up to 40 different evaporation prot-des simultaneously, and use

feedback from sensors to maintain or modify a given evaporation profile. This device uses a microcomputer,

humidity sensors and various analog and digital interlaces under the control of custom software to effect the desired

evaporation profiles. The first device has been used to show the dependence of the evaporation profile on the size

and number of crystals obtained lor a given solution condition. This device has proved extremely useful in showing

that the crystals obtained for a given condition greatly depend upon the rate at which water is evaporated from a

growth solution. The man features of the second device includes the ability to: evaporate water from a growth

solution at virtually any rate, quantitatively monitor the water evaporated over time, detect and respond to nucleation

events sensed by laser scattering, and perform six replicates of one user defined evaporation profile utilizing a

Master/Slave configuration. This device 'also includes a microcomputer, a humidity sensor, various analog and

digital interlaces, and custom software tot controlling the system. Additionally, a laser scattering subsystem

consisting of a laser, photodetector and fiber optics is used to detect nucleation events. This recently constructed

device is currently being used to show the improvement that detection of nucleation and modification of the

evaporation profile while the experiment is in progress can have on the crystal growth results.

11-2 7
II. MSADProgramTasks-- Flight Research Discipline: Biotechnology

i i i oi ! m_ o o in ! o la Qo ! | | i i no I u 11 | I oo Ii o | lln i oBi I i im| i o o i o i o Qo | | o ig o n | o n i s i i | i o ao ii o o io o | i o i ! a o | a o i io i i o i o i | i o o I a o | a oo _ a o i | I I i o i i o o ia i ii o I i a i I I It o s |! o in o I! o | i u i i o no | oo i ig I * I a | I oo |! a o | aa | o ! ! o I | I o| o m| o o ol a oil o itl nu I Io la_ I_| Ho |_o |oo |oo ol | ! I | |1 o I! o |1

• DCPCG-Temperature

Automated dynamic control of protein crystal growth using temperature as a control parameter has been achieved.

Results were presented at the 46th Annual Southeastern Regional Meeting of the American Chemical Society held

in Birmingham, AL during October 16-19, 1994. The main features of the device include thermoelectric heating and

cooling between about 5-50°C + 0.1 °C, laser scattering detection of nucleation, and user programmable temperature

profiles tot automated response to nucleation and subsequent growth conditions. The device has been used to prove

the detection and reversibility of nucleation and the dependence of nucleation on various solution conditions such as

protein concentration, pH and crystallizing agent concentration. The initial version of the device provided unilorm

temperature control of the entire protein solution volume. That feature proved to be useful for studying nucleation

response to solution conditions, but was unsatisfactory for producing crystals with size suitable for x-ray analysis.

Uniform temperature simply produces too many growth sites and a resultant shower of crystals. Second and third

versions of the device are presently under study in which a localized temperature gradient (or sting) h_ been

incorporated in an attempt to minimize the number of growth sites, thereby producing larger crystals. These

systems are currently being tested; preliminary results are encouraging in that fewer but larger crystals have been

grown.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 4/93 EXPIRATION: 3/98

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-23-08-06

MS Students: I MS Degrees: 1 NASA CONTRACT NO.NAS8-39762

PhD Students: 3 PhD Degrees: 0 RESPONSIBLE CENTER: MSFC

11-28
II. MSAD Program Tasks -- Flight Research Discipline: Biotechnology

Electrophoretic Separation of Cells and Particles from Rat Pituitary

PRINCIPALINVESTIGATOR: Dr. Wesley C. Hymer Pennsylvania State University

CO-INVESTIGATORS:

A. Mastro

R. Grindeland

R. Snyder

Pennsylvania State University

NASA Ames Research Center (ARC)

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The objectives are to separate (1) pituitary cells and (2) hormone containing granules by tree flow electrophoresis

using the Japanese Free-flow Electrophoresis Unit (FFEU) on Earth and in space.

TASK DESCRIPTION:

To accomplish these objectives it is necessary to: (1) opttmize conditions for maintaining live pituitary cells in

Japanese cell culture kits (CCK) for 21 days; (2) remove cells fron the CCK in space and t_actionate them by

electrophoresis; and (3) break open the cells in space and fractionate the lysate by electrophoresis to obtain

hormone-containing granules. These procedures must be done in such a way as to be executable in flight. It is also

necessary to modify existing technologies in order to analyze different hormone lorms of growth hormone and

prolactin in these tractions. Both hormones will be assayed by both immune and biological assays.

Because FY94 was the flight year for this experiment, the logistics associated with conducting pre-flight, flight and

postflight operations was also required.

TASK SIGNIFICANCE;

(1) Pituitary growth hormone and prolactin are required/'or proper function of the bone, muscle and immune

systems. Because these systems are modified by spaceflight, and because the results from 4 previous space

experiments show that the biological activities of growth hormone and prolactin are diminished during and after

spaceflight, this experiment is intended to probe the mechanism(s) by which these changes occur.

(2) Biotechnology research on earth routinely utilizes coupled technologies to meet focused objectives. Coupled

technologies are difficult to accomplish in a low gravity environment; yet these will be routine on Space Station

Alpha. This experiment serves as a prototype tor such activities.

PROGRESSDURING FY 1994:

(1) The flight experiment was carried out during the IML-2 mission (July, 1994).

(2) Preliminary data document microgravity-induced changes in growth hormone cell structure and function.

(3) Coupled technology procedures were successfully carried out in flight.

(4) Preliminary data regarding growth hormone are to be presented at the Darmstadt, Germany meeting in

November, 1994.

(5) Active postllight analysis continues.

(6) A repetition of the entire flight experiment on both the ground and flight FFEU hardware in Japan is being

planned.

e_1_e_O_t_e_e1_I_o_I_t_e_e_j_t_i_e_et_o_D_o_t_e_O_Ii_I_e_4_i_a_Q_i_i_i_

11-2 9
If. MSAD Program Tasks -- Flight Research Discipline: Biotechnology

t I | | I | I s I | e I|, I | I I I I I o | H | I I| I | II | | SI |tt| ! I! I II ! ! ! | SI I | ! I ! | I ! | I! ¢ I I. I | I 0 0 | | I II I II | I I ! t I I I | ¢ I II II | I ! I I I I I !I I! III I I| 0 |! e I! PI I | | I I I ! I I ! | ! 011 ! | I Ie I I I I m| | I I e; I I I ! IS | II I I I e I | e | I | | I I | IG¢ DI | I i | | S| I I | II I; I SJ I PI! 011 | I I I | t I | I | DI| I 0 | | |P | ! | | SI | I ! I! I U ! eH e I

STUDENTS FUNDEDUNDER RESEARCH: TASKINITIATION: 12/89 EXPIRATION: 6/95

PROJECTiDENTIFICATION:963-23-01-01

NASA CONTRACTNo.: NAGS-953

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Hymer, W.C., Shellenberger, K., and Grindeland. R. Pituitary cells in space. Adv. Space Res., vol. 14, 61-70 (1994).

Books

Perez, F.M., Deaver. D.R., and Hymer, W.C, "Why use a flow cytometer for cell analysis'?" in "Endocrine Research

Techniques." Edited by: F. de Pablo, C.G. Scanes, and B.D. Weintraub Academic Press, Inc.. pp 157-179, 1993.

Presentations

Gudi, T., and Hymer, W.C. "GRP94: A molecular chaperone in rat pituitary tissue." Thirteenth Summer Symposium in

Molecular Biology, The Pennsylvania State University, University Park. PA, August, 1994.

t en_el lie|el |e oee p|lop ee nllte eeil_ ppo|||p |ll | oI pit| etoe seep e1ppibpc| eieeso peeeeepen e|! ||! |1| n! i el eel |11 lee l e| eel psi e,cHoeoeo e|slleo eo| 110¢1oe pe e| | eei | ee| ! s | ieo iell el | oe| eell ee| sel eN eel eel Ill lee st oil p llo ppeepeei| IpeepoOooet opoo! | I e| | eoI eel Is| | I

I1-3 0
II. MSADProgramTasks-- Flight Research Discipline: Biotechnology

i i i in i i i ii i ii t i i i i i i i i n i n n i II i i i i i i i i i i |i i I I I | i i in| i i ii ii i i i i i i i i |n| J n |i i ni n i i | n | i i i I i i i i io I * I i i i i i i i i i I I I ii i i 0111 n i t i nI iI I I o I I n i i t I I II I I I i I I I I | I I |! I I | i! I i | i I i | i | I I I i I i i I n i i| i ii i | I I I I i I I e I I| ! I| i i i I 011111111 H i t H t i i | i i | iI i Ii i | i i i i i i | i i i| e | I I I * i

An Observable Protein Crystal Growth Flight Apparatus

PRINCIPALINVESTIGATOR:Dr. Alexander McPherson, Jr. University of California, Riverside

CO-INVESTIGATORS:

S. Koszelak

A. Ma]kin

Y. Kuznetsov

A. Kathman

A. Dodds

M. Garavito

University of California, Riverside

University of California, Riverside

University of California, Riverside

Teledyne Brown Engineering

University of California, Riverside

University of Chicago

TASK OBJECTIVE:

The task objective is to initiate research and development efforts in the area of macromolecular crystal growth, and

specifically tocused on the direct observation of the relevant phenomena as they pertain to the design and ulttrnate

flight of an observable protein crystal growth apparatus (OPCGA).

TASK DESCRIPTION:

The experiment objective included the identification and characterization of candidate biochemical systems that

included proteins, nucleic acids, and viruses. It further included the construction of an optical platform that would

be suitable for detailed intefferometric analysis of protein crystal growth experiments and the visualization of

concentration fields, the time lapse microphotography of macromolecular crystals, and the further characterization of

the mechanisms and fundamental parameters that determine the features of macromolecular crystal growth.

TASK SIGNIFICANCE:

The need for structural information on biological macromolecules is of paramount tmportance to the emerging field

of biotechnology. Such information provides the basis for the rational design of pharmaceuticals, the determination

of enzymatic mechanisms and the engineering of proteins to enhance or modify their function. The value of X-ray

crystallography to provide structural information at atomic resolution is unsurpassed. This technique does,

however, depend on the availability of crystals for the macromolecule under study, and furthermore, which possess a

high degree of intemal order and suitable size and shape to 'allow the accurate collection of X-ray diffraction data.

Typically, crystals grown in the earth's gravitational field suffer from one or more types of flaws which decrease the

structural information that can be derived from them. These imperfections include the relatively simple, but

nonetheless adverse, problem of intergrowth. In a 1-g field several crystals which nucleate independently, sediment

to the bottom of the growth chamber where they intergrow into a mass not suitable for X-ray diffraction analysis.

Such intergrowth or the appearance of satellite crystals, which were earlier thought to occur by nucleation at the

sides of defects in pre-exitmg crystals, have been shown to be almost exclusively due to the effects of sedimentation

and inter growth. The value of a microgravity environment for the elimination of sedimentation in the preparation

of these crystals is obvious. Early experiments conducted on board the space shuttle clearly indicated such benefits.

They also provided the impetus for other researchers to design experiments and procedures for mimicking the effect

of microgravity in ground based experiments. The development of methods for successfully growing protein

crystals in gels is an example of such activities.

PROGRESSDURING FY 1994:

Research continued with the objective or defining the critical science requirements tot design and construction of an

advanced protein crystallization facility for space station, and other carriers likely to be available in the interim.

This research has included time lapse video microscopy of protein crystal growth, the application of quasi elastic

light scattering to prenucleation events, and more recently the introduction of both Mach-Zehnder and Michelson

11-3 1
II. MSAD Program Tasks -- Flight Research Discipline: Biotechnology

i, _i o|| s | o|,, o, |, o| |, I ¢ looI aoL,., ui, | Ql l o|1 o, a. oaoooooo! oI oo!,,,, uo ,,, il o| i o, ,,,, a, t,, o,, o, uo, I., l |oao| o, o| | oI l| la o, oo, ooo, oonao, Ioo, oo, a., i, | o, oo| osgon,, |, o,, e uo|,, o, ,, o, u. i, |o|,. |, ooo| o, ¢oH o la., ;o, o, | I oouoo lu., ao¢, J Ioa Ill |.| | ,, ,o ! o,, .o | oo| o|

mterlerometry. Substantial progress has been made in advancing these techniques for macromolecular

crystallization. The size of the critical nucleus, surface free energy, and activation energy have been estimated for

several systems that include both viruses and proteins. Interferometry ha,_ been used to visualize growth sources on

growing crystal surfaces, to measure tangential and normnl growth rates, and to measure the heights and slopes of

growth hillocks arising from dislocations.

The International Microgravity Laboratory (IML-2) mission was successfully completed in July and the results have

been "analyzed by a number of techniques including X-ray diffraction. Some substantial successes in growing

protein and virus crystals were achieved and a report of these results for publication is now being assembled. Most

important among these were (I) the demonstration that cubic crystals of satellite tobacco mosaic virus, and both

rhombohedral and hexagonal crystals of the plant seed protein canavalin, diffracted to significantly higher resolution

than ground grown controls. (2) The largest particle that has been attempted was successfully crystallized for the

first time. This was the plant virus Turnip Yellow Mosaic Virus (TYMV). Importantly, some distinctive

alterations in the morphology of the space grown crystals were clearly evident, (3) Unique morphological changes

were seen for microgavity grown crystals of hexagonal canavalin and tuna cytochrome c.

STUDENTS FUNDED UNDER RESEARCH: TASKINITIATION: 5/93 EXPIRATION: 5/98

PROJECTIDENTIFICATION:963-23-08-07

NASA CONTRACTNO.: NAS8-3963

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Cudney, R., and McPherson, A. Screening and optimization strategies for macrmolecular crystal growth. Acta Cryst., vol.

D50. 414-423 (1994).

Day, J., Ban, N., Patei, S., Larson, S.B.. and McPherson, A. Characterization of crystals of satellite panicum mosaic

virus. J. Mol. Biol., vol. 238, 849-851 (1994).

DeLucas. L.J., Long, M.M., Moore, K.M., Rosenblum, WM., Bray, T.L., Smith C., Carson, M., Narayana. S.V.L., Carter.

D., Clark, D., Clark, Jr., A.D., Nanni. R.G.. Ding J., Jacobo-Molina, A., Kamer, G.. Hughes, S.H., Arnold, E.. Einspahr.

H.M., Clancy, L.L, Rao, G.S.J.. Cook. P,F.. Harris. B.G.. Munson, S.H., Finzel. B.C.. McPherson, A., Weber. P.C.,

Lewandowski. F., Nagabhushan, T.L., Trotta, P.P., Reichert, P., Navia, M.A,, Wilson, K.P., Thomson, J.A.. Richards,

R.R.. Bowersox, K.D., Meade, C.J.. Baker, E.S., Bishop, S.P., Dunbar, B.J.. Trinh, E., Prahl, J., Sacco, Jr.. A., and Bugg,

C.E. Recent results and new hardware developments for protein crystal growth in microgravity. J. Cryst. Growth, vol.

135, 183-195 (1994).

Felden, B., Florentz, C., Oieg_, R.. and McPherson. A. A histidinylatable tRNA-like fold at the 3' -end of satellite tobacco

mosaic virus RNA. Nucleic Acids Res., vol. 22. 2882-2886 (1994).

Larson, S.B., Greenwood, A., Cascio, D., Day, J., and McPherson, A. The refined molecular structure of pig pancreatic

a-amylase at 2.1 ,_ resolution. J. Mol. Biol., vol. 235, 1560-1584 (1994).

Malkin, A., and McPherson. A. Light scattering investigations of nucleation processes and kinetics of crystallization in

macromolecular systems. Acta Cryst., vol. D50, 385-395 (1994)

Patel. S., Cudney, and McPherson, A. Crystallographic characterization and molecular symmetry of edestin, a legumin

from hemp. J. Mol. Biol.. vol. 235, 361-363 (1994).

Patel, S., Cudney, R., and McPherson, A. Using a silica hydrogel for macromolecular crystallization. Acta Cryst., vol.

D50, 479-483 (1994).

anI i ne! I loll igl iiI Ill oill O|ll oi i ei ! eI i oi Illl !lie ! O! ! I 1OII l ! I OI OI I I aI II O II O! I I l OO! Oa iiI uo| I l I I OI ! ! I O! !IO II! uoI I oI |ll !OI Ill IIIo I Oil I ! I OI ! OnI I in I ooI eoi i ! I I ! ! o| i i i ! o| ! o! l oI I I I I iiI I eoi nooI Ill eeeeeeleooel_teo! oo!111eel ooooils ell! e! DII sl! e! !i ee! I eel ! ssa!sineeis ! el! I

II-3 2
II. MSAD Program Tasks -- Flight Research Discipline: Biotechnology

Weisgraber. K.H.. Newh_mse. Y.M., and McPherson. A. Crystallization and preliminary X-ray analysis of human plasma

ap_litl(3protein C-I. J. Mol. Bi_fl.. vol. 236, 382-384 {1994).

Prot:ecdil|_S

l_:ul. NH., F,scobar. C.. Gaarcia, R.. Hasel, K., Day. J., Greenwood, A., and McPherson, A. "Crvstal struclures of an

anti idimypic lab and of the idiotype-antiddiotype complex." Proc. Natl. Acad. Sci. USA, 91, 1604-1609 (1994).

Books

McPherson, A. "Crystallization of Biological Macromolecules" in "Handbook of Crystal Growth." Edited by: T. J. Hurlc

vol. 2 A, pp 419-463, 1998..

b,lcPherson, A. "The Role of X-ray Crystallography in Structure Based Rational Drug Design" in "Rational Drug Design."

('RC ['tess, 199,_.

"_i_i_il_¢_o_i_iiil_"_i_mmi_ii_l_i_m_i_m_||_i_H_imm_i_i_m_i_|i_|_|_m|m|_m|ii_iu_||_|_i_i| ill e , . i , . ¢i tlll.l u|l|lln u l.lllilllililtlllllU*Ulllllll.,,_,

11-33
Electrophoresis Technology

PRINCIPAL INVESTIGATOR: Dr. Robert S. Snyder NASA Marsh'all Space Flight Center (MSFC)

CO-INVESTIGATORS:

P. Rhodes

T. Miller

G. Roberts

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

Roberts Associates, Inc.

TASK OBJECTIVE:

The task objectives are to study the effects of sample concentration and dielectric constant on sample stream

distortion and the limits of the electrohydrodynamic stability of the sample stream in the absence of shear flow.

TASK DESCRIPTION:

The electrophoresis separation process can be considered to be simple in concept, but flows local to the sample

filament produced by applied electric field have not been considered. These electrohydrodynamical flows, formulated

by G.I. Taylor in 1965 for drops suspended in various liquids, distort the sample stream and limit the separation. In

addition, electroosmosis and viscous flow, which are inherent in the continuous-flow electrophoresis device,

combine to disturb further the process. Electroosmosis causes a flow in the chamber cross section which directly

distorts the sample stream, which viscous flow causes a parabolic profile to develop in the flow plane. These flows

distort the electrophoretic migration of samples by causing a varying residence time across the thickness of the

chamber. Thus, sample constituents at the center plan will be in the electric field a different length of time and

hence move more or less than comparable constituents closer to the chamber wall.

Both horizontal and vertical laboratory electrophoresis test chambers have been built to test the basic premise of

continuous-flow electrophoresis that removal of buoyancy-induced thermal convection caused by axial and lateral

temperature gradients will result in improved pertormance of these instruments in space. These gravity-dependent

phenomena disturb the rectilinear flow in the separation chamber when high-voltage gradients and/or thick chambers

are sued, but distortion of the injected sample stream due to electrohydrodynamic effects causes major broadening of

the separated bands observed in these chambers.

The initial part of the proposed space experiment was planned to be done in the French electrophoresis hardware

(RAMSES) on the second International Microgravity Laboratory (IML-2). This hardware has the capability of

applying the required voltage at 1,000 Hz which can permit the dielectric dependence to be determined. Two

different frequencies were planned to vary the dielectric constant of the samples and the cross-section illuminator

used to show the sample ftlament cross section, and recorded photographically. This experiment was not done on

IML-2 because of a hardware failure on orbit.

The experiment can be accommodated on a later RAMSES flight, or available TEXUS electrophoresis hardware,

with its cross-section illuminator, can be supplied with the required high-frequency power supply. These

measurements can then be completed during a short-duration rocket flight. Additional opportunities are being

evaluated.

TASK SIGNIFICANCE:

Since the Continuous Flow Electrophoresis System (CFES) built by the McDonnell Douglas Astronautics

Company achieved results in space on seven shuttle missions that were influenced by electrohydrodynamics, these

scientific phenomena are a critical part of electrophoresis in space. The severity of sample distortion due to

dielectric constant variations is poorly known in the laboratory because of the concurrent sample concentration

effect.

I1-34
PROGRESSDURINGFY 1994:

Most activities during FY94 were directed toward adapting our requirements to the RAMSES design for IML-2

which flew in July. The borate buffer preferred by the European Principal Investigators (PIs) was optimized for our

polystyrene latex samples. A prototype RAMSES chamber was built in which we tested our latex sample stream

distortions and "also perlbrmed a separation of two different latex particle sizes. This chamber was "also used in crew

training for our portion of the RAMSES experiment.

We have completed experiments using our miniature electrohydrodynamic test chamber where we observed a

conclusive dielectric effect on the sample studied. We have taken these results and compared them to the dielectric

constant effect observed in drop determination of immiscible fluids. We will now quantify a selection of

polystyrene latex particles with respect to Debye length, zeta potenti,,d, and particle radius. The dielectric constant

of this selection can then be determined as a function of frequency by observation of sample stream distortion in our

chamber.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 9/89 EXPIRATION: 9/95

PROJECT IDENTIFICATION: 963-23-08-04

NASA CONTRACT NO.: In-house

RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Books

Rhodes, P.H., and Snyder, R.S. "Chapter 3, Theoretical and Experimental Studies on the Stabilization of Hydrodynamic

Flow in Free Fluid Electrophoresis" in "Cell Electrophoresis." Edited by: J. Bauer CRC Press, Inc.. 1994.

Presentations

Rhodes, PH., Snyder. R.S.. and Roberts, GO. "Role of dielectric constant in electrohydrodynamics of conducting fluids."

2nd Microgravity Fluid Physics Conference, Cleveland. OH, June 21-23, 1994.

Snyder, R.S., and Rhodes, P.H. "The NASA electrophoresis program." The International Aerospace Congress, IAC '94.

Moscow, Russia, August 15-19, 1994.

i i ii i i! I II I I I I I Il!il i i i I ii i i i i ! ii i i i i i i i i i i i! | Ii i i i l i i i l i l I Ii I Il I I I i i i i ii i ! l ! l l i I l i i ii ! i i i l i i i! l I I I I l i I ! ! i i! i li l i i i i i I I I l ! I ! Ii I i i ii i !il !il I (i i i! I ! I I | I Ii l l i ii l ii i ! i I I I l I i l l i i i ill i! I I I l I i iii i ii ! i i i i i i i i I ! I I i i, i ii i l i i ! i i i i i iI I ! l i I ! I | ! I I Ii I ill i i i I I

ii-3 5
Scientific Support for an Orbiter Middeck Experhnent on Solid Surface Combustion

PRINCIPALINVESTIGATOR:Prof. Robert A. Altenkirch Mississippi State University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this flight experunent is to determine the controlling mechanisms of flames spreading over solid

fuels in the absence of buoyant or externally imposed, gas-phase flows. Ground-based testing of flame spreading in

quiescent microgravity environments has identified the qualitative importance of radiative heat losses in determining

flame spread rates, but these tests are too short in duration to establish spreading flames without residual effects of

the ignition process.

TASK DESCRIPTION:

The Solid Surface Combustion Experiment (SSCE) is to be built and flown to perform a minimum of eight

experiments. The experiments are to consist of five flame spreading tests using a thin fuel, varying the

atmospheric composition and pressure, then three additional tests using a thick Iuel with fewer variations of the

same parameters. In these tests, measurements of the fuel and flame temperature are to be made and recorded, and

the flames are to be photographed, using motion picture film. A parallel effort is to be made to develop a complex

numerical model of the opposed-flow flame spread problem, including the important effects of surface and gas-phase

radiative losses. Finally, a detailed, quantitative comparison of experimental and computed results for flame

spreading over thin and thick fuels in various oxidizer and pressure environments is to be performed including

comparisons of spread rate, temperature and heat transfer fields and the structure of the flame.

TASK SIGNIFICANCE:

The spreading of flames over solid fuels is a fundamental combustion problem that has practical significance in the

prevention and control of fires. Flame spreading in normal gravity is usually dominated by buoyant air flow that

introduces a significant complexity into the fundamental models of the phenomena. Experiments conducted in the

microgravity environment nearly eliminate this complexity, providing a more fundamental scenario for the

development of flame spreading theory.

PROGRESSDURINGFY 1994:

During the year, the seventh flight of the Solid Surface Combustion Experiment (SSCE) was completed aboard the

Shuttle Discovery during the STS-64 Mission. This flight was the second for the PMMA (polymethyl

methacrylate) thick fuel phase of the flight program in which the fuel was ignited and burned in an atmosphere of

50% Oxygen/50% Nitrogen at a pressure of 2.0 times normal atmospheric pressure.

Other major accomplishments of the year include:

1. The results of the sixth flight of the SSCE, the first to use PMMA, included the observation that the

thermocouples, near and imbedded in the fuel samples to measure temperatures, may have influenced the spreading

flame by absorbing or conducting heat. A series of ground based tests was conducted to evaluate this influence,

which has not been previously observed. Based on these tests the flight configuration of the thermocouples for this

year's flight was changed from the original design to use much smaller thermocouple wire (l/5th the size of the

original) for the gas-phase measurements. Preliminary studies of the most recent flight results show no indication

of interference from the gas-phase thermocouples.

11-36
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

t | i o ! t o o | o ! Ig o i i o o 11 o n i o i i o oo o ! _ i o i o o I i o t i ot i a ! v | i i i i i i o o i ia i ii i i o i i o I i t n i* n i * n I a | i g * i io i ii i i a n I o I ii i io i i o o * o o i o o i ao t * | * o o o o o I oo I o | i o o n n o I i o o I *o ia _ i i o o i I o o I o o o o o Ia o o o o o H o *. i oo o o o o o |o a o Iu o. o ii o o o i o o io ia o oo o i | i i o a o i oo | a _ II o i i o | i o o iu iii o i i o i i o

2. The two samples burned on the sixth flight of the SSCE, the first to use PMMA, showed a high degree of

repeatability in the flame spreading measurement. The Principal Investigator recommended reconfiguring the

software in the seventh flight so that the first sample would be quenched to obtain surface regression measurements,

and the second sample would not be quenched to obtain observations of non-spreading burning after the flame

reaches the end of the sample specunen. The preliminary results of the seventh flight indicate that this objective

was achieved.

3. The results of the sixth flight of the SSCE indicated surface temperatures of the PMMA samples higher than are

normally observed in Earth gravity experiments. The results of the recent seventh flight show more conventional

temperatures and indicate the probability that the surface thermocouples in the sixth flight were uncovered by fuel

pyrolysis, and hence surface regression, during the retarded flame spreading caused by the gas-phase thermocouples.

4. The results of the seventh flight of the SSCE indicate that repeatability of the experiment, from the perspective

of the flame spread velocity, is again quite good. The temperature data from the two tests are of high quality and

can be assembled into an integrated temperature field. These temperature data can be compared direcdy to

temperatures computed by the numerical models developed by the Principal Investigator and can be further used to

calculate heat transfer rates between the flame the fuel and the surroundings.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/84 EXPIRATION: 12/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-22-05-01

MS Students: 8 MS Degrees: 8 RESPONSIBLE CENTER: LeRC

PhD Students: 2 PhD Degrees: 1

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Bhattacharjee, S., Altenkirch. R.A.. and Sacksteder, K.R. The effect of ambient pressure on flame spread over thin

celluosic fuel in a quiescent, microgravity experiment. To appear in J. of Heat Transfer. (1994).

Bhattacharjee, S., Bhaskaran, K.K., and Altenkirch, R.A. Effects of pyrolosis kinetics on opposed-flow flame spread

modeling. Combustion Science and Technology, Vol. 100. 163 (1994).

Bullard. D.B., Tang, L., Altenkirch, R.A., and Bhattacharjee, S. Unsteady flame spread over solid fuels in microgravity.

Adv. Space Res., vol. 13, no. 7, 171-184 ('1993).

West, J.. Bhattacharjee, S., and Altenkirch, R.A. Surface radiation effects on flame spread over thermally thick fuels in an

opposing flow. J. of Heat Transfer, vol. 116, 646-651 (1994).

Presentations

Ramachandra, P.A., Altenkirch, R.A., Tang, L. Wolverton, J.K.. Bhattacharjee, S. and Sacksteder. K.R. "The behavior of

flames spreading over thin solids in microgravity." Twenty-Fifth Symposium (International) on Combustion, to appear in

Combustion and Flame, 1994.

I I I OlOllIII IlI I OI OIO I I tll nOil OO0OIl 0O0O OI OI IO OO01OI OI I I IO OI I I OI i i i l i i l i i i i I i i OOOi i Oi i OOi Oi i Oi i i i Oi i i i i i ii ilOlllO Oi i Oi i i noOO0OOIO I Io oo* i i oi oi ii i In ni i ioii oiino i i l I i aoai i I OO1011III OI I OOIO OI! I Ill I OI I I OI II IIII Ill l I III OII I IOi OOl ii Oi i i Ii i ii i ii i OIO Oui i

11-3 7
Low-Velocity, Opposed-Flow Flame Spread in a Transport-Controlled, Microgravity Environment

PRINCIPAL INVESTIGATOR: Prof. Robert A, Altenkirch Mississippi Slate University

CO-INVESTIGATORS:

S. Bhattachanlee

S.L. Olson

San Diego Slate University

NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The overall objectives of the proposed work are to uncover the underlying physics and increase the fun "damental

understanding of the mechanisms that cause flames to propagate over solid fuels against a low velocity flow of

oxidizer in the low-gravity environment. Although the work is fundamental in nature, it has clear applications to

tke safety in space and on Earth. Specific objectives are:

1. To analyze experimentally observed flame shapes, measured g&s-phase field variables, spread rates, radiative

characteristics, and solid-phase regression rates for comparison with theoretical prediction capability previously

developed that will be continually extended.

2. To investigate the transition from ignition to either flame propagation or extinction in order to determine the

characteristics of those enviromnents that lead to flame evolution.

TASK DESCRIPTION:

To meet the ohiectives of the research program, a series of experiments has been developed to exercise several of the

dimension'd, controllable variables that affect the flame spread process in microgravity. Those variables that will

be changed from expertment to expermaent are the opposing flow velocity (l-20cm/s), the external radiant flux

dtrected to the fuel surface (0-2) W/m:, and the oxygen concentration of the environment (35-70%). An experiment

matrix is used that minimizes the number of experiments to be conducted in order to obtain the information needed

to meet the scientific objectives of the effort.

Because the amount of data to be collected is limited, modelling is necessary to interpret the results and to sort out

the important physics of the phenomenon. The modelling effort that will support the experimental program is

numerical in nature and includes the capability to solve model flame spread problems over both thermally thin and

thick fuels posed as steady-state, eigenvalue problems tot spread rate or as unsteady problems from ignition through

llame spread. In each approach, the two-dimensional continuity, momentum, species, and energy equations in the

gas and the continuity and energy equations in the solid are solved using the SIMPLER algorithm. Gas radiation

is included in the model to assist in the interpretation of species-specific emission data obtained with band

pass-filtered video cameras in the experiments.

TASK SIGNIFICANCE:

Radiative heat transfer is critical to these and many other microgravity flame spread experiments, and so radiant

heating will be imposed, and radiant beat loss will be measured. These are the first attempts at such experimental

control and measurement in microgravity, and the experimental results and numerical modelling will allow the role

of radiation, as well as diffusive transport, in these flames to be delineated.

PROGRESSDURINGFY 1994:

in October 1993, Learjet-based, reduced gravity tests of the effect of the laser diode on flame spread were successfully

conducted. In November 1993, the Science Requirements Document was upgraded to reflect the improved

understanding of the diagnostics requirements tbr the experiment. Unsteady 2D flame spread computations were run

with a variable low gravity level, to sunulate the Learjet test conditions.

_tt_tnt_n_t_tt_4_n_t_utt_tt_t_t_ut_t_u_tu_tt_tu_u_ttn_t_*_t_t_t_t_*_u_t_tt_t_tnt_tt_t_tt4*_t_ttgt_n_n_I_*_t_ut_*t_tt_t_tt_t_nt_tt_tu_*_t_t_t_t_t_;_

11-3 8
In December 1993 the Science Requirements Document was I-realized. In Januarv, DARTFire held a very successlul

RDR.

In February, another Lear jet series was llown which reve',ded a problem with the laser diode system. Excellent data

were obtained, however, with the intensified array camera used for flame imaging. Non-unity Lewis ntnnber

capability was added to the unsteady numerical code, and work to incorporate a two-flux radiation model to the code

began. The steady code was used to determine the sensitivity of the flame spread to g level. Computations showed

that for g levels below 10-3, the effect is pretty small.

In March, the effect of variable Lewis number was examined for the Nkse case of the DARTFire test matrix. While

the unity Lewis number case extinguishes, the non-unity Lewis number propagates with significant differences in

fuel vapor, water vapor, and carbon dioxide distributions. The fuel surlace concentration of fuel vapor is three times

that of the unity Lewis number case. Doug Seaton defended his thesis "A Complete Parametric Study of Flame

Spread Over Thin Fuel in Forced-Convective and Microgravity Environment" at San Diego State University.

In April, Dr. Lin Tang visited Prof. Subrata Bhattacharlee to compare the steady and unsteady codes.

Thermocouple vacuum tests were conducted to determine the effect of the laser on the thermocouple readings.

In June and July, work on reconciliation of the steady and unsteady codes was completed. 'Validation' of the

unsteady thick fuel model continued. The problem ota flame spreading over a thermally thick solid is an

inherently unsteady problem because of the changes of boun "dary.layer thickness and the length of pyrolysis zone as

the flame spreads. It is assumed that at any given instant, the problem can be treated as a steady problem which is

the hypothesis used by Tien for a thin fuel (1979). Based on this hypothesis, a series of steady-state results was

compared with the unsteady results. Good agreement was obtained for cases where the variable fields for the steady

case are used as initial conditions for the unsteady case. However, for cases with an ignition transient, the Ilarne

spread rates are lower by about 30%. This is attributed to the low thermal diffusivity of the condensed phase such

that the solid temperatures downstream of the flame are much lower than predicted from steady-state theory. Thus

heat losses in depth are larger for the unsteady computations, and the llame propagates more slowly.

In August, DARTFire held a CDR. Computationally, the influence of gas-phase kinetic properties on ignition,

flame structure and solid vaporization temperature were studied in hopes of reproducing PMMA Leaflet experimental

results. The predicted flame appearance agrees with the experimental one: the flame is thin, close to the fuel

surface, and somewhat curved. The predicted flame moves closer to the surface when the activation energy is

assumed smaller than the base case. The computational results show that the influence of gas-phase kinetic

properties on surI_ace evaporation temperature is sm_di. The dependence of the flame spread velocity, Vf, on

opposed-flow gas velocity, V v Ior thick/uels was investigated lot a fully developed flow m a channel geometry. A

simple formula for the spread rate was constructed as an extension of the de Ris fornmla and works well not only

for the correct dependence of V eon V_, but "also for predicting the flame structure. Work is now m progress on using

band radiation to assist in the selection of the transmittance of the optical filters to be used in the experiments.

In September, the steady model was successfully applied to the case of "excited" flames, i.e., those that are

irradiated. With an external flux of 1 W/cruZ, the spread rate increases by almost five times. Additionally, because

the DARTFire geometry is, strictly speaking, a channel flow, differences between the open boundary layer flow that

we have been assuming and the channel flow have been investigated. Three flames have been compared: 1) llame in

an externally imposed flow, 2) flame on one side of a channel wall, and 3) flame on two walls of a channel

(equivalent to solving a lraif-channel problem using a symmetry condition at half the channel height). Results

indicate that 1) and 3) are stmilar in spread rate (less that 1% difference), but the velocity lielcts are dissimilar near

the center of the channel.

The open flow produces a significantly diftErent spread rate though because of the acceleration of the flow in the

channel. Unsteady computations of channel flow have also been carried out from ignition through spread to the end

of the sample. The spread rate falls from ignition and eventually approaches a relatively constant value, i.e., the

same as the steady predictions. At present, we are working on including soot radiation in the radiation model and

code and are checking previous work on variable properties.

1I-3 9
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 6191 EXPIRATION: 11/98

BS Students: 1 BS Degrees: 0 PROJECT IDENTIFICATION: 963-22-05-02

MS Students: I0 MS Degrees: 3 RESPONSIBLE CENTER: LeRC

PhD Students: 1 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Bullard, D.B.. Tang, L., Altenkirch. R.A.. and Bhattacharjee. S. Unsteady flame spread over solid fuels in microgravity.

Adv. Space Res., vol.13, no.7, 171-t84 {1993).

West, J. Bhattacharjee, S. and Altenkirch, R.A. Surface radiation effects on flame spread over thermally thick fuels in an

opposing flow. J. Heat Trans., 116. 646-651 [1994L

Presentations

Bhattacharjee, S., Charles, T.L.. and Altenkirch. R.A. "Modelling gas-phase radiation from laminar flame spreading over

solids." ASME Winter Annual Meeting. New Orleans. November 1993.

Olson, S.L., Hegde, U, "Imposed radiation effects on flame spread over black PMMA in low gravity." Fall Technical

Meeting of the Eastern States Section of the Combustion Institute, December 5-7, Clearwater Florida, 1994.

West, ]., Bhattachaxjee, S,. Rameriez, B and Altenkirch, R.A. "Low Reynolds number flow near the leading edge of a

burning and non-burning plate in a mocrogravity environment." AIAA/ASME Thermophysics and Heat Transfer

Conference, Colorado Springs, CO June 20-23. 1994.

___e___|_||__|_||t_|I_||__|!__|__!|_!__!|___|__|________||_____!_!_I_|_|_|__u|__||_t________|__|t I|l||Sllllll!llllllll||!ltll||l||t |l!lll!lllllllelll|t ____I_||__|_!II||_|||_____|_||__|I_|_____|_||_____!_|__||_||I|______I______I___*|_|_____*___

11-40
Reflight qt: the Solid Sur&ce Combustion Experiment with Emphasis on Flame Radiation Near

Extinction

PRINCIPAL INVESTIGATOR: Prof. Robert A. Altenkirch Mississippi State University

CO-INVESTIGATORS:

Prof. S. Bhattacharjee

K.R. Sacksteder

Dr. M. Delichatsios

San Diego State University

NASA Lewis Research Center (LeRC)

Factory Mutual Research

TASK OBJECTIVE:

The objective of this flight experiment is to determine the mechanisms of flame spreading over solid fuels in the

absence of buoyant or externally imposed, gas-phase tlows. This experiment is an extension of the Solid Surface

Combustion Experunent with the purpose of observing flame spread with radiative losses near the flammability

limit.

TASK DESCRIPTION:

The Solid Surface Combustion Experiment (SSCE) is to be reflown to perform additional tesk_ and to obtain

quiescent flame spread data for cylindrical, thermally thick fuels. In these tests, measuremenLs of the fuel and flame

temperature are to be made and recorded, and the flames will be photographed using motion picture film. The

numerical model, developed as part of the SSCE project, is to be further extended to predict flame spread behavior

over cylindrical samples in which the geometry of the gas-pha, se radiative interactions are simplified

computationally. A detailed quantitative comparison of the experimental and computational results is to be

performed" including comparisons of spread rate, temperature field, heat transfer rates, and flame structure.

TASK SIGNIFICANCE:

The spreading of flames over solid fuels is a fundamental combustion problem that has practical significance in the

prevention and control of fires. Flame spreading in normal gravity is usually domanated by buoyant air flow that

introduces a significant complexity into fundamental theoretical models. Experiments conducted in the

microgravity environment nearly eliminate this complexity, providing a more fundamental scenario for the

development of flame spreading theory.

PROGRESSDURING FY 1994:

This is a new task in Fiscal Year 1994 beginning with the award of a new flight experiment pr0iect entided,

"Reflight of the Solid Surface Combustion Expertment with Emphasis on Flame Radiation Near Extinction," under

NRA-93-OLMSA-1, "Microgravity Combustion Science: Research and Flight Experiment Opportunities."

Since the award of the new flight experiments the following accomplishments have been achieved:

1. Formulation began on the analytical treatment of flame spreading on a cylindar in a quiescent environment: this

is distinct from the existing numerical modeling efforts. This treatment will include provisions for radiative losses

from the flame/fuel system, leading to a model suitable lor predicting flame spreading in the microgravity

environment.

2. From the experimental point of view, the reflight project has been separated into two distinct parts: the first

effort will be to choose an additional test condition, compatible with the existing SSCE-PMMA test mamx, but

attempting to observe a flame very near the flammability limit. The second effort will be to develop a cylindrical

sample to simplify the modeling eflort required to simulate the gas-phase radiative losses dominating the flame

spreading phenomenon in microgravity.

1I-4 1
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 5194 EXPIRATION: 11197

PROJECT IDENTIFICATION: 963-15-0E

RESPONSIBLE CENTER: LcRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

West. J.. Bhattacharjee, S., and Altcnkirch, R.A. Surface radiation effects on flame spread over thermally thick fuels in an

_)pposing flow. J. heat Trans., w)], 116. 646-651 (1994).

i i I i iI I l I III i I ii II I i i II II I It I U I Iii ii I I Ii i Iii Iii I II Iii ii I I l I ii i I ii i I I i i t i i I i iI I I i i I I i l I l l l* II I I i I i I I I lI I i i ii i I III I II ii i i Ii i ii I II Ill l I II iII II I i i l I I II III III I II II I It i lI I i I I II I I III I IIII III IIi rill III III n i ii ii iii i ii i ii ii i i i I i i i i l i i l i i I i ii i i i i i i i i Ii i

114 2
Il. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

l i l I Ill i l lll l II l _ II Ill I I II I Ill 1$ III I I l I Ill, II Ill i Ill l,lll I l I l, II I l llllilll,lllllll l I I III Ill III l llllli I I III I i I I III III l I l I I l l I l illl l III Ill l I n 11111 I I I If I Ii I i II l II III I I ill i i i I III III ill II I II III I Ii I III l llil I III I i lll.lllli l llll l lillnllll ,lllil l lllll

Gravitational Effects 0_1 Laminar, Transitional, and Turbulent Gas-let Diffusion Flames

PRINCIPALINVESTIGATOR:Dr. M. Y. Bahadori Science Applications International Corporation (SAle)

CO-INVESTIGATORS:

Dr. Uday G. Hegde NYMA, Inc.

TASK OBJECTIVE:

Tile overall objective of this program is to improve our fundamental understanding of microgravity gas.jet diffusion

flames in the entire laminar, transition',d, and turbulent regimes. Specifically, tests are to be conducted in

microgravity with the purpose of (i) determining the effects of buoyancy on these flames, (ii) determining the

relative importance of buoyancy-induced turbulence oll flame characteristics, and (iii) revealing phenomena which

may be masked by buoyant convection.

TASK DESCRIPTION:

In order to achieve these obiectives, the progrmn pursues two distinct but complementary paths, as follows:

(a) Investigate the effects of fuel type, flow rate, Reynolds number, nozzle size. and gravity on (i) global flame

characteristics (such as flame shape, height, radiation and temperature), (ii) the extent of the transition regime, (iii)

turbulent flame features, and (iv) stand-off characteristics and blow-off conditions. These tests will be conducted in

normal-gravity and in the NASA LeRC ground-based facilities, including the Drop Tower, Zero-Gravity Facility,

and/or aircraft. The measurements include temperature, thermal radiation, pressure, acceleration, and flame nnaging.

The data will be used to validate detailed analytical and numerical models of these flames.

(b) Identifying the mechanisms involved in the generation and interaction of observed large-scale structures which

directly influence the flame characteristics noted under (a). This part revolves an investigation to be carried out in

space, which utilizes a controlled, well-defined set at disturbances to reread the mechanisms that govern the

dynamics of large-scale structures interacting with flame fronts under microgravity conditions. This will further our

understanding of the naturally occumng disturbances that are an inherent part of the transitional and turbulent flames

of part (a). As in part (a), a combined analytical and numerical modeling effort will be an integral component of this

phase of the program.

TASK SIGNIFICANCE:

Our previous results have shown significant differences between normal gravity and microgravity tlame

characteristics and structure. Understanding the role of buoyancy on turbulent combustion may lead to

improvements in the design of engines and furnaces.

PROGRESSDURINGFY 1994:

Previous findings (1991-93) came from ground-based studies of high-Reynolds-nmnber laminar, transitional, and

turbulent gas jet diffusion flames in microgravity. These findings include larger microgravity turbulent flame

heights and blow-off Reynolds numbers, increase in flame height with increasing Reynolds number during the

transition process in microgravity, and smaller flame stand-off distances and higher blow-off Reynolds numbers for

microgravity flames compared to those in normal gravity. In addition, the transition process is different in

microgravity, where instabilities initiate at the base of the flame with an intermittent behavior in these naturally

occurring disturbances. In contrast, the normal-gravity flames are observed to show the transition process at the tip

of the flame through random instabilities.

These observations have now been confu'med through numerical studies of the flame flowfield and calculations of

the critical layer for the axisyrnmetric mode via shear-layer instability considerations. The observed convective

!I--4 3
II. MSADProgramTasks-- Flight Research Discipline: Combustion Science

velocity of the large-scale structures is in good agreement with theoretical estunates. Tests have also shown that

transport processes can be influenced by the effects of buoyancy, i.e., the effective diffusivity in microgravity is

smaller than in normal gravity tot the transitional and turbulent flames.

The science requirements tot an experiment involving forced pertirbations of a laminar flame were presented during

October 1993 in a Science Concept Review at the NASA Lewis Research Center. The Science Panel concluded that

the proposed experiments have scientific merit, the Investigators have justified the need Lot microgravity

experiments, and that the objectives can only be met by a space experiment that provides an extended duration of

microgravity conditions. The Science Panel recommended the following: (a) Focus on axisymmetric

perturbations, (b) Quantify velocity perturbations generated by the disturbance mechanism, (c) Demonstrate that the

fuel will not condense in the space experiment, (d) Demonstration of adequate resolution of the imaging system,

(e) Increase the sampling rate of temperature measurements, and (f) Pertorm a calculation to optimize the

radiometer location. The foUowing is the progress in addressing these issues:

A series of approximately 15 tests in the Zero-Gravity Facility have been identified for addressing these

recommendations and to check out the flight test matrix. Analytical and numerical modeling are also underway for

these efforts. In addition, since none of the recommendations has a major impact on the design of the flight

experiment, design has continued in parallel with the ground-based tests. It is anticipated that the Investigators and

the Engineering team will be ready for RDR in early 1995.

The design of the axisymmetric-perturbation mechanism was completed and tests showed that the components work

properly to provide the required frequencies and amplitudes of oscillation. Smoke visualization tests were

satisfactorily conducted at LeRC in support of the flame/disturbance interaction characterization tot flight

experiment. Observations of the imposed vortex generation, convection, and interaction with the jet were made.

The tests did not indicate any influence of swirl on the dynamics of the imposed vortex and subsequent entrainment

into the jet, and led to a change in hardware design to reduce flow nonuniformities. In addition, LDV measurements

currently in progress at Georgia Tech (through a subcontract) have shown good results for the 3-D velocity field of

the vortex/jet interaction. Preliminary analysis of the data indicates that axial and radial components of velocity are

indeed influenced by the vortex-generating system, whereas the tangential (i.e., swirl) component of velocity does

not show this correlation.

Currently, work is underway to demonstrate that the flight camera provides adequate temporal and spatial resolution

to measure the amplitude and convection velocity of the flame perturbations. Some of the verifications will be

performed as part of the LeRC Zero-G Facility tests in FY95.

Measurements of the thermocouple time constant and radiometer time constant were conducted in normal gravity

tests. The circuits for these measurements are being tested in LeRC's laboratories. Using established spectral

analysis techniques, the temperature readings will be corrected, and tests are planned in the Zero-G Facility with the

increased sampling rate. Should the ground-based tests show the need for the high sampling rate, provisions will be

made to modify the flight hardware tot sampling the temperature data at these rates.

Numerical calculations were perlormed to optimize the radiometer location tor the flight experiment. Calculations

for the normal-gravity flames are in good agreement with predictions of other researchers, which show that the

optimum location of the radiometer is at a non-dimensional axial distance (with respect to the flame height) of

0.5-0.7. For microgravity flames, the predicted results show that the optimum location is at a non-dimensional

distance of 0.3-0.5. These predictions (which demonstrate the eftects of buoyancy on flame radiative characteristics)

will be compared with the results of the Zero-G Facility tests for further model validation and confh,mation of the

optimum radiometer location for the flight experiment.

The modeling etlbrt consists of analytical and numerical simulations of gas jet diffusion flames under the influence

of imposed disturbances. To date, laminar base-flame calculations Lbrflight experiment have been conducted. An

analytical model tor disturbed flames has been tbrmulated and time-dependent flame behavior predictions are

generated. Detailed numerical computations of a time-dependent, Navier-Stokes model are in progress, Disturbed

11--44
[I. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

|t.t "_a_"an_naoo_u_o_jIlu_oI_I|_o_ooo_1onaoI_o_otot_t_oHn_ona_Hu_on_o_o_oot_| .tlHIIollolnlnnoaaonaou o lHtJ|llmt inonlltttot i stlottutllotloolltolloooloaootoolaot Hlnolollo|ottoooHotooololt|oo|eoaotlooao|oototeuo

cold iets and hot jets are currently under investigation. Numerical simulation of the jet transient development under

the experiment condition is obtained. Jets with both axial and radial pulsations (initial test of the model) have been

studied. Detailed modeling of iris-induced flowfield in jets is in progress, and the results will be compared with the

LDV mea_surements. Also. this comprehensive transient model is currently being extended to include the laminar

flame in the presence of the iris-generated disturbances.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 11/91 EXPIRATION: 11/96

PROJECT IDENTIFICATION: 963-22-05-03

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Hegc, U.G. Heat release effects on the instability of parallel shear layers. A1AA journal, vol. 32, no. 1, 206-207 (1994).

Books

Bahadori. M.Y., Stocker. D.P., Vaughan. D.F. Zhou. L.. and EdeLrnan, R.B. "Effects of buoyancy on laminar, transitional.

and turbulent gas jet diffusion flames." in "Modern Developments in Energy, Combustion. and Spectroscopy." Edited by:

cddited by F.A. Williams. A.K. Oppenheim, D.B. Olfe, and M. Lapp. Pergamon Press. Oxford, pp 49-66. 1993.

Presentations

Hege, U.G., Zhou, L., and Bahadori, M.Y. "Transitional and turbulent gas-jet diffusion flames in microgravity." Paper

AIAAO4-0432, AIAA 32nd Aerospace Sciences Meeting, Reno. NV, January. 1994.

II-.4 5
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

J01|lll|ll|l!l|;llllll|0111|ll|lll0110a|lll|l j|_li!I_i_l_Iiil|l_i_I_!_iiiiit_o_1_tiiiiI_iQ_o_iiiiii_i_|_io_Iim_i_iill| .lllllll|lllt _i_i_!_i_t_ii;i|_Ii_i1_i_iIii|!I!i_i_|i_iiii|Ii_iii_Ioii_i_e|_o_|t |lel!llll|ll

Sooting Effects in Reduced Gravity Droplet Combustion (SEDC)

PRINCIPALINVESTIGATOR:Prof. Mun Y. Choi University of Illinois, Chicago

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

To determine the effects of sooting on droplet combustion characteristics using opdcal and intrusive techniques.

The parameters to be studied include burning rate, flame dynamics, extinction, disruption and soot particle

dynamics.

TASK DESCRIPTION:

The sooting behavior will be studied using expanded beam line-of sight extinction and subsequent 3-point Abel

deconvolution to determine the soot volume traction distribution; two-wavelength optical pyrometry to determine

the soot temperature within the region between the flame and the droplet; and thermophoretic

sampling/transmission electron microscopy to deter]nine the soot morphology (radius of gyration, primary particle

size, fractal geometry, etc). Feasibility studies will 'also be performed using Laser-lnduced-Incandescence techniques

to determine droplet soot volume fraction.

These experiments will be perlormed tor a wide range of conditions to vary the sooting propensity of the droplet

using various fuels, pressure, oxygen indices, droplet dimension and inerts as parameters. In addition,

computational modeling of the soot particle dynamics using the balance between thermophoresis and Stefan drag

will be compared with the expertrnental measurements. The modeling eflbrt.s will be advanced interactively with

the experimental measurements of the soot volume fractions and the soot particle dimensions.

TASK SIGNIFICANCE:

The combustion of a pure, single-component liquid droplet provides an ideal problem from which to obtain valuable

information for both basic and applied scientific purposes. The importance of the isolated droplet burning process

has promoted extensive experimental and theoretical investigations for more than 40 years. In terms of the practical

relevance, the knowledge of individual droplet burning characteristics provides insights into some of the more

complex mechanisms involved in spray combustion. Since estimated energy production through spray combustion

processes accounts tor more than 25% of the world's output, droplet combustion remains a viable field lor continued

research.

Since the pioneering microgravity droplet combustion experiments of Kumagai and coworkers back in 1957, there

have been numerous theoretical, computational and expermaental studies analyzing the burning characteristics of

isolated droplets. However, sooting effects have typically been neglected due to the complexities involved (both

experimental and computational/theoretical). However, recent microgravity experiments indicate that soot/sootshell

formation affects all four of the important measurable parameters involved in droplet combustion: burning rate,

flame diameter, extinction and disruption. Thus, our understanding of the burning characteristics of droplets can

only be complete by considering a detailed study of the sooting behavior for a wide range of characteristic times and

dimensions.

In all previous microgravity studies, the degree of sooting was estimated by visual observations of the sootshell.

This study will focus on the effects of sooting on the droplet burning rate, flame dimensions, extinction and

disruption by accurately measuring the soot volume fraction, temperature and soot morphology and dynamics.

These measurement of the temperature and soot volume fractions will also prove beneficial in assessing the

importance of radiative heat transfer.

_o_I_I__1_Q_t_D_o_I__I___m_

11-.-46
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

PROGRESSDURINGFY 1994:

1. Motivations aa_d concepL'_ for space experiments were presented to the engineering team prior to the start of the

QFD (Quality Function Deployment) process. The PI participated in initial QFD sessions at LeRC to provide

input regarding the Science Requirements. The meetings yielded an initial cut at the science and engineering

requirements for the flight experiments. The product of the QFD process is to identify potential high-risk features

of the experiment to guide the choice of which experimental elements will be breadtx)arded first. The subsystems ot

the expertment which will be breadboarded are the data storage system, droplet deplo)_nent system, droplet size

measurement system, soot volume fraction measurement system, soot temperature measurement system and

thermophoretic soot sampling system.

2, The PI was at Lewis during the summer months working with Dr. Randall Vander Wal and Dr. Karen Weiland on

tmplementing Laser-lnduced Incandescence for performing soot volume traction measurements in droplet

combustion. Dr. Randall Vander Wal and the PI are considering performing LII experiments in reduced-gravity

droplet combustion (on DC-9) during the summer of 1995.

3. Tlie PI has acquired a combustion chamber from LeRC for use in normal-gravity feasibility studies to be

performed at UIC. For reduced-gravity testing in the ground-based facilities, discussions were held with the DCE

(Droplet Combustion Experiment) pmiect scientist to use the DCE drop rig for some preliminary tests with the PI's

proposed fuels. A droplet combustion chamber which utilizes several features of the DCE drop tower hardware is

being fabricated to take advantage of the design solutions. It is anticipated that an operational rig to be used in the

DC-9/2.2 sec drop tower will be readv by early sununer of 1995.

4. A full-field normal-gravity experimental apparatus to perform soot volume traction and temperature

measurements was designed and implemented at UIC. Performed normal gravity soot volume fraction expenment_

using toluene, benzene, decane and hepmne at I atm, 0.5 atm and 0.25 atm.

5. Developed an interactive Abel-deconvolution algorithm to determine soot temperature using two-wavelength

pyrometry for lull-field data (512 by 512 pixel locations). Developed image processing program (using Data

Translation Ii'ame grabber boards) that can produce the extinction and emission output files for direct use in the Abel

deconvolution program. Tested the Abel deconvolution program using known distributions which produced very,

good comparisons between actual and predicted soot volume fractions. Developed similar programs to determine

temperatures from 900 nm and 1000 mn emission data. Tested various wavelength combinations (700nm/g00nm,

800nm/900nm, 900nm/1000nm) to determine best combination that will produce accurate result.,; and low detection

temperatures.

6. Developed a digital image processing program to determine the radius of gyration from transmission electron

micrographs that are obtained using thermophoretic sampling techniques. The students are fully trained in TEM and

Selected Area Electron Diffraction Analyses.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 5/98

BS Students: 0 PROJECT IDENTIFICATION: 963-15-0B

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: '_

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Vander Wal, R., Dietrich. D.. and Choi. M.Y. "Relative soot volume fractions in droplet combustion via laser-induced

incandescence." Presented at the Eastern States Section of the Combustion Institute, Clearwater. FL. December 5-7. 1994.

11-4 7
II. MSADProgram Tasks -- Flight Research Discipline: Combustion Science

it | i i i i ii ! a| i i ei | I i i_ i ii I i i i i i i 11 | i || i| i i ! i I 1411 o| Mi i i i i i i i Ill I I nI nMI |M| |H | I I I I I I I I DI I I | I I I I I I I _|I O! I J | I I | II |I _| III I I I I | | II 1111111111 | _I I I I _| I II I qI I I I I I I I I I I I II I II I I I I I |! | ! | | I! !nlI III IN |1 | | I| I I I I I I I ! O|I 0|1 I! ! 011 | |1 U I |1 ! | I ! | II I! I 0I! I lie I I011

Candle Flames in Microgravity

PRINCIPALINVESTIGATOR:Dr. Daniel L. Dietrich NYMA, Inc.

CO-INVESTIGATORS:

Dr. Howard Ross

Prof. James S. Tien

NASA Lewis Research Center (LeRC)

Case Western Reserve Univerity

TASK OBJECTIVE:

The goal of this work is to further investigate some of the features of candle flame combustion observed during a

recent small scale candle flame experiment conducted on board the space shuttle. These are specifically as follows:

1. To observe whether a steady flame can exist in a purely diffusive environment;

2. To understand from a fundamental aspect the observed near-extinction llame oscillations;

3. To examine the nature of the interactions between two candle flames.

As a secondary, objective, we will use the candle as a model system (non-propagating, steady-state diffusion

(non-convective) flame) to investigate buoyant scaling arguments for diffusion/lames. Testing and scaling analysis

to date shows that utilizing reduced presure, enhanced oxygen environments do not produce a buoyancy-free

environment, as currently published scaling arguments suggest.

TASK DESCRIPTION:

These objectives will be accomplished by a program consisting of the development of a comprehensive numerical

model of the candle flame, ground-based testing in normal-gravity laboratories and drop towers, and another

small-scale glovebox experiment.

The development of a comprehensive numerical model represents the most significant addition to the proposed

program. The gas-phase model will be a modification of an existing two-dimensional code developed tbr flame

spread over solid fuels under the gui "dance of one of the investigators. The initial model for the wick/liquid phase

htLs already been developed by the principal investigator.

The ground based testing will utilize existing drop rigs and other existing expertmental equipment to fully

characterize the candle flame in a range of ambient conditions (i.e., atmospheric to sub-atmospheric pressures,

nitrogen-oxygen, helium-oxygen ambients). The data will be imaging of the flame, thermocouple measurements,

LDV and possibly PIV, all of which the investigators have experience using. The use of more advanced diagnostics

will also be explored during the later phases of the program.

The space experiment will be a glovebox experiment that is similar to the existing Candle Flame in Microgravity

glovebox experiment (same mvestigators). The minor proposed changes will be: a larger tree volume, the

performance of the thermocouple measurements (a capability that existed but was not used on the last experiment

because scheduling conflicts), the ability to maintain a large candle spearation distance and to simultaneously ignite

the two candles.

TASK SIGNIFICANCE;

The candle flame in microgravity is a unique/model system (non-propagating, steady-state diffusion

(non-convective) flame). The data from this work is expected to improve our understanding of diffusion llames on a

fundamental level.

11-48
II. MSADProgramTasks-- Flight Research Discipline: Combusl_on Science

laon_o_H_"_io_o_n|_oo_ounn_oo_o_I_H_o_n_o_|o_onaoo_n_n_o_Io_Io_I_"_on_o_Iuooo_io_i_noI_lion_o_au_o_oI_oot_o_non_o_o_on_iDanoIo_o H ollnonlloooHlllaollopaoolnollooolilatllouloHnllolalllOllonllno.

PROGRESSDURING FY 1994:

A Case Western Reserve University graduate student, J. Konecny, began working the modeling aspect of the

problem in June. The initial formulation of the computational model is complete and implementation of the

computer code is nearly complete. The candle will be treated as a saturated porous material at a constant temperature

which greatly simplifies the wick and coupling of the wick and gas phase. The gas phase will solve the full

Navier-Stokes equations with a smaplified radiation model and one step chemistry.

Drop tower tests in the 5.2 second drop tower of two candles on axis candles with simultaneous ignition were

conducted. Oxygen ambients of 19, 18, 17, and 16 percent with different inter-candle separation distances were

tested. The results showed no ignition of either candle at 16 percent 02, and successful ignition and burning at both

19 and 18 percent. The results are currently being analyzed.

A prototype design for a liquid candle (porous metal wick with a pure liquid fuel) was completed. This is being

considered as an "alternative to solid candles to simplify comparisons with the theoretical predictions. The Candle

Flames project was also selected as a glovebox experiment aboard the MIR glovebox. This purpose of this project

is to complete some of the work not done on the USML-L candle flames experiment and serve as a precursor to the

current experiment.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 4/98

BS Students: 0 PROJECT IDENTIFICATION: 963-15-0B

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

II--49
Investigation of Laminar let Diffusion Flames in Microgravity: A Paradigm for Soot Processes in

Turbulent Flames

PRINCIPAL INVESTIGATOR:Prof. Gerard M. Faeth University of Michigan

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The flight project is an experimental and theoretical investigation ot the mechanisms of soot tormation in laminar

jet diffusion flames under conditions of low buoyancy.

TASK DESCRIPTION:

Several types of experiments have been conducted. The majority have been in normal gravity, studying the

influence of gravity by varying the ambient pressure. In addition, experiments have been conducted on NASA's low

gravity aircraft, (the KC-135 at JSC). The work has tocussed on mapping soot volume tYaction, temperature, soot

particle size and gas species in a variety of hydrocarbon flames. The flight experiment will be limited to

measurement of soot volume traction, soot particle size and some temperatures.

TASK SIGNIFICANCE:

In most flames of practical interest, soot radiation is the dominant mode of heat transport to combustor components

and a dominant mechanism tbr flame spread and growth. The experimental results, combined with theoretical

modelling will confirm or deny the applicability of the conserved scalar tormalism to soot properties in diffusion

flames. These results, when combined with those of ground-based low- and normal gravity experiments will

increase the current fundamental understanding of soot formation processes in both laminar and turbulent flames and

increase our ability to model them. Consequently this will have a significant impact on our understanding of

systems such as the spread of unwanted fires, design of jet engines and large scale boilers, among others.

PROGRESSDURINGFY 1994:

October: Additional property measurements have been conducted along the axis of the weakly buoyant flames,

concentrating on samples for soot structure and TEM analysis of the samples. Measurements of the acetylene

flames were reduced in order to study mechanisms of soot nucleation, growth and oxidation: the results indicated

gross soot nucleation rates that were first-order in acetylene and gross soot growth rates that were roughly

second-order in acetylene. Other data is being accumulated for various fuels. Finally, the LSP experiment had a

successful RDR.

November: Measurements and data analysis continued in the weakly-buoyant flames considering results for

acetylene Ks well as other fuels. Results tbr acetylene were completed and a paper describing the findings was

prepared tbr the 25th International Symposium on Combustion; these results confirmed findings that soot

nucleation was roughly first-order in acetylene with a modest temperature dependence (an activation energy of

roughly 23 kcal/gmol) while growth is roughly second-order in acetylene concentration with a negligible activation

energy. Additionally, our findings concerning soot growth in diffusion flames are similar to existing findings in

premixed flames, although our nucleation rates are smaller than results of earlier studies (but the earlier work has

considerable uncertainties about soot reactive surface areas).

December: Measurements and analysis of weakly-buoyant acetylene flames continued, emphasizing soot nucleation

and growth. In addition, concerns about effects of acetone contamination of acetylene were addressed (acetylene is

stored in contact with acetone), finding negligible effects of acetone on our results. Our newest findings about soot

nucleation support first-order behavior in acetylene but growth rates appear to be somewhat lower than the

second-order behavior round last month. Developmental test results concerning laser extinction measurements by

imaging at LeRC were reviewed.

11-5 0
It. MSADProgramTasks-- Flight Research Discipline: Combustion Science

*l*om*uIIIIIIIIiimlleiiomoil,iiiIi|,lliiiill.l. fI*li*i;;llail*llt*i.li_l*i111aii,_l.i .l.l m.lJli**ilIH.HIij*i;_ill!li|*liiHilll*|H*iiilllllm *IIIeIlUIIOIIOIl* m mi|* m ll.a**m|iIiiiiUiieiiOH *OOIIIIeI***IIOi*Ui*Otiiii

January: Study of soot growth in weakly-buoyant acetylene flames continued, with additional measurements added

to the data base. This growth data are being reduced considering (1) raw data with growth due to acetylene only, (2)

raw data assuming a first-order acetylene reaction (which is conventional wisdom in the literature) and an effect of

age, and (3) as a net reaction rate allowing for oxidation by the low levels of oxygen present in the soot growth

region (roughly 1% by volume) using the Nagle/Strickland-Constable soot oxidation results. The last appears to be

most reasonable and yields a collision efficiency/or acetylene of roughly 0.4%. In addition, a test campaign on the

KC-135 for LSP was attempted when the KC-135 was at NASA LeRC. The campaign was largely unsuccessful

because a nearby experiment on the aircra/t developed a leak and sprayed the Gas Jet rig's electronic systems with a

conductive water solution.

February: Study of soot nucleation and growth continued, with some anomalous data remeasured and all data

reanalyzed. The soot growth results continue to hold up and still are similar to results in premixed flames, although

we do not detect an effect of soot age on growth that generally is observed in premixed flames. Soot nucleation has

remained first order in acetylene, with a low activation energy of 33 kcal/gmol. Measurements of flame and soot

structure/'or fuels other than acetylene were initiated.

March: Study of soot nucleation and growth continued in order to resolve effects of soot oxidation by oxygen,

carbon dioxide and water vapor. The Nagle/Strickland-Constable expression was evaluated based on our

measurements of soot oxidation rates: the expression was at least order of magnitude correct. It also was found that

water vapor and carbon dioxide are important for soot oxidation in the growth region, which affects the apparent

order of soot growth with respect to acetylene (tending to make it larger than the actual order with respect to

acetylene). The revised results, allowing lor effects of oxidation by oxygen, carbon dioxide and water vapor,

indicated soot growth via acetylene collisions with a collision efficiency of roughly 0.5%. Measurements continued

for a variety of fuels in diffusion flames, considering both weakly-buoyant low pressure flames and buoyant flames

at alanospheric pressure. In view of the relationship between present measurements and those in prenuxed flames,

we began assembly of a premixed flame apparatus in order to carry out new measurements in prenuxed flames with

better definition of soot surface areas than past work. A revised SRD was prepared and sent to LeRC for review.

April: Measurements continued in both weakly-buoyant and buoyant flames l.or a variety of fuels (ethylene, ethane,

propane, propylene, butadiene and butane). In view of the number of flames to be considered (six) and the number

of variables to be measured (soot volume tractions, soot temperature, soot structure, gas temperature, gas velocities

and species concentrations) these measurements will require several report periods to complete and analyze. Work

'also continued on the development of the premixed flame apparatus. Round V of the KC-135 test was undertaken

yielding new results for ethylene flames that currently are being analyzed.

May: Data ti'om the KC-135 test was analyzed to find the correlation between burner mass flow rates and luminous

flame lengths at low gravity; it was found that the length is independent of burner diameter and pressure lbr a given

fuel flow rate but required fuel flow rates are larger then earlier esttmates for a given flame length. These results

were checked using weakly-buoyant diffusion flames, indicating little effect of burner diameter and pressure on the

luminous flame length, similar to the KC-135 results. Tests "also were undertaken to establish imaging techniques

for multiline temperature measurements: this work will continue for the next few report periods. The P.I. attended

the PDR and was generally satisfied with the design.

June: Measurements continued in order to resolve flame and soot structure for the various flames. A portion of

these results involved measurement_s of species concentrations for an ethane flame; these measurements were in

excellent agreement with estimates based on the universal state relationships developed earlier in this laboratory.

Analysis of soot growth and nucleation t'or weakly-buoyant acetylene and butadiene flames was completed; these

results are in fair agreement with our earlier acetylene mechanism but more measurements are needed before tLrrn

conclusions can be made. Test flames similar to those of Harris and Weiner have been set up on the premixed

burner and we currently are working to resolve problems of flame disturbances. Measurements of flame lengths as a

function of fuel flow rate for low gravity and weakly-buoyant conditions were completed; these results confirm that

larger fuel flow rates are needed for a given flame length than thought previously. Tests to evaluate multiline

temperature measurements by tmaging continued, emphasizing effects of improved spatial resolution (or collection f

number); evaluation of the results based on extrapolation of radiation-corrected thermocouple measurements from

11-5 1
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

soot free regions was satisfactory. A more definitive ev'aluatton will require 'alternative temperature measurements

in the soot-containing region: such measurements based on the emission and absorption properties of carbon dioxide

in the infrared are being considered.

July: Measurements to resolve flame and soot structure properties for various fuels (ethylene, ethane, propane,

propylene, butadiene and butane) burning in air were completed; these results currently are being analyzed to find

soot nucleation and growth rates as well as continued evaluation of universal state relationships for hydrocarbon

diffusion flames. Measurements of premixed ethylene/air flames were initiated finding soot volume fractions in

reasonably good agreement with earlier measurements of Harris and Wiener; these measurements will continue

throughout the next report period. Direct evaluation of the multiline temperature measuring system, based on

imaging, will require an instrument system capable of measuring temperatures in the infrared based on the carbon

dioxide bands; this arrangement currently is being designed.

August: Data from various fuel/air diffusion flames were analyzed to find soot nucleation and growth rates; results

indicate an ethylene growth channel having a collision efficiency of 1.8% which is parallel to the acetylene growth

channel while nucleation rates were correlated by acetylene similar to acetylene/air flames; a paper describing these

results is being prepared while analysis of state relationships continues.

September: Some gaps in data relevant to fuel/air diffusion flames were found during preparation of a paper

describing these results; thus measurements were completed to rectify this problem while preparation of the paper is

nearing completion. Measurements of soot volume fraction distributions in the premixed ethylene/air flames were

completed; work on soot temperatures began. Analysis of soot nucleation and growth was completed in three

acetylene/air flames in order to check earlier results for different soot paths and flame conditions; results did conftrm

our earlier results and a Brief Communication is being prepared to describe the findings. Analysis of imaging

measurements of soot volume fractions obtained at NASA-LeRC was undertaken. All these activities required that

work on state relationships and on the evaluation of the multiline soot temperature measuring system had to be

deterred; we hope to make more progress in these areas during the next year.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 2/92 EXPIRATION: 2/98

BS Students: 0 PROJECT IDENTIFICATION: 963-22-05-04

MS Students: 2 RESPONSIBLECENTER; LeRC

PhD Students: 1

BISLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Farias. T.L., Carvalho, M.G.. Koylu. U.O. and Faeth, G.M. Computational evaluation of

Rayleigh-Debye-Gans/fractal-aggregate theory of the absorption and scattering properties of soot. J. Heat Trans. (in

press).

Koylu. U.O. and Faeth G.M. Optical properties of overfire soot in buoyant turbulent diffusion flames at long residiner

times. J. Heat Trans.. vol. 116, 152-153 (1994).

Koylu, U.O. and Faeth, G.M. Optical properties of soot in buoyant laminar diffusion flames. J. Heat Trans, (in press).

Law, C.K. and Faeth, G.M. Opportunities and challenges of combustion in microgravity. Prog. Energy Combust, Sci,,

vol. 20, 65-113 (1994).

Sunderland, P.B., Mortazavi. S.. Faeth, G.M. and Urban, D.L. Laminar smoke points of nonbuoyant jet diffusion flames.

Combustion and Flame, vol. 96. 97-103 (1994).

Presentations

Faeth, G.M. "Soot morphology and optical properties in nonpremixed flame environments." Proceedings of the Spring

Technical Meeting, Canadian Section of the Combustion Institute, Kingston. ON, Canada, 2-1 to 2-5. 1994.

11-$ 2
Faeth, G.M. "Issues in premixed and nonpremixed combustion." DOE Workshop on Fundamental Research in Support of

Industrial Combustion Needs. [rvine, CA. 1994.

Faeth, G.M., Sunderland, P.B., Koylu, U.O. and Urban, D.L. "Laminar jet diffusion flames in microgravity: A paradigm

for soot processes in turbulent flames." Proceedings of International Symposium on Aerospace and Fluid Sciences,

Tohoku University, Sendai, Japan. 185-198, 1993.

Farias, T.L.. Carvalho. M.G.. Koylu. U.O. and Faeth, G.M. "A computational study of the absorption and scattering

properties of soot." Proceedings of the Fall Technical Meeting, Eastern Section of the Combustion Institute, Pittsburgh.

PA. 394-397, 1993.

Farias, T.L., Carvalho, M.G.. Koylu. U.O. and Faeth, G.M. "Scattering properties of polydisperse soot aggregates."

Eurothem Seminar No. 37: Heat Transfer Radiating and Combusting Systems -2, Saluggia, Italy, in press. October 1994.

Koylu, U.O., Faeth, G.M., Farias, T,L., and Carvalho, M.G, "Fractal and projected structure properties of soot

aggregates." Combust. Flame, in press.

Koylu, U.O., Sunderland, P.B., Mortazavi, S. and Faeth. G.M. "Soot nucleation and growth in weakly-buoyant laminar jet

diffusion flames." 32nd AIAA Aerospace Sciences Meeting, Reno, NV, AIAA Paper N(_. 94-0561, 1994.

Sunderland, P.B. and Faeth, G.M. "Soot formation in hydrocarbon/air laminar jet diffusion flames." Proceedings of the

Fall Technical Meeting, Eastern Section of the Combustion Institute, Pittsburgh, PA, in press, December 1994.

Presentation Sunderland, P.B., Koylu, U.O. and Faeth, G.M. "Soot formation in weakly buoyant acetylene-fueled laminar

jet diffusion flames burning in air." 25th Symposium (International) on Combustion. lrvine. CA, August 1994.

Presentation Sunderland, P.B., Koylu, U.O. and Faeth, GM. "Soot fl)rmation in hydrocarbon-fueld jet diffusion flames

burning in air." 25th Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, poster paper,

abstract only, 1994,

Presentation Sunderland, P.B,, Koylu, U.O., Faeth. G.M. "Soot lbrmation in acetylene-fueled laminar jet diffusion flames

burning in air." Proceedings of Spring Technical Meeting, Central States Section, The Combustion hastitute, Pittsburgh,

275-280. 1994.

Presentation Sunderlasnd. P.B., Koylu, U.O. and Faeth, G.M. "Soot lormation in weakly buoyant acetyleme-fuled laminar

.jet diffusion flames burning in air." 251h Symposium (International)on Combustion. lrvine. CA, Combust. Flame. in

press, August 1994.

II-5 3
[l. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

Ill..I II111 I B_le I MIII I Ill01 II _ III I III II III I I11 M011 III Ill II 1011_ll.lJll. 1.1111. I MIII. I I QI I I I I. I II mI .I..I Jltl UII M1Ill41 MI llll _ III III I ml I III I IH Ill Ill. Ill Ige .I Ill I I DI II..llllnllllnlu JU I IIII I llnllllUllHlltllllllllllll*ll JHI Jl

Unsteady Diffusion Flames: Ignition, Travel, and Burnout

PRINCIPALINVESTIGATOR:Dr. Frank Fendell TRW

Co-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective is to investigate the adequacy of frequently adopted, simplified mathematical models to describe the

behavior of laminar flames, primarily diffusion flames, by comparison with definitive experimental data, made

available by burning in a microgravity environment.

TASK DESCRIPTION:

The experiment investigates the adequacy of frequency adopted, simplified mathematical models to describe the

behavior of laminar flames, prtmarily diffusion flames, by comparison with definative experimental data,

conveniently available from burning in a microgravity environment.

TASK SIGNIFICANCE:

To study parametric variation of stoichiometric proportion and reactant dilution at ignition to provide sufficient data

to test the adequacy of simplified analyses Iiequendy used to predict diffusion-flame behavior in different practical

applications. The work is particularly pertinent for flames (and near-cold-wall quench layers) involving natural gas,

hydrogen, butane, propane, or other fuels that are in the gas phase at atmospheric temperature and pressure.

PROGRESSDURING FY 1994:

Experimentally, the layout of the apparatus is close to final. Parts' lists have been generated, and are ready to be

placed with TRW purchasing agents, after a final critique of the design. Conceptual design of the test chamber is

completed. The design will be finalized after discussions with the parylene-film manufacturer in Goleta, CA.

LeRC provided information about H20 spectral emission characteristics, spark and hot-wire ignition electrical

circuitry, and power requirements on the space shuttle and station to TRW. LeRC also sent TRW the results of

adiabatic flame temperature calculations, done by the Project Scientist, Dr. Suleyman Gokoglu, for different initial

stoichiometric proportions and reactant dilutions to help the decisions regarding experimental design and operating

conditions.

The plan is to initially segregate hydrogen diluted with argon, and oxygen diluted with helium, into two equal

halt-volumes within a squat rectangular-solid-configured container with isothermal, noncatalytic, impervious walls.

The contents of the two half volumes are each to be at atmospheric pressure and temperature, and to have equal

density, so that the "average molecular weight" for each half volume is the same. The overall contents are to be

sufficiently fuel-deficient such that. if (conceptually) the initial, segregated contents of the container were mixed to

form a perfectly homogeneous gaseous mixture, the adiabatic flame temperature (equilibrium bumed-gas

temperature) would be consistent with a vigorous diffusion flame, but not so hot that either dissociation of product

species (mainly water vapor) or gaseous radiative heat transfer or the physical integrity of the container is of

concern.

In practice, a thin parylene film seems a candidate material to serve as the impervious initial interface, to be

perforated on command at multiple sites by the movement of an intrusive "array" of pointed prongs, at least some

of the tips of which are to serve as spark electrodes. Ignition is to occur "alter a short interval to enable some

reactant interdiffusion. The diffusion flame is to propagate into that half volume which is free of the intrusive

device. The key objective is to measure the flame temperature and flame position as a function of time until

depletion of the deficient reactant (hydrogen) results in extinction of the planar diffusion flame.

_q_D_*D_O__1_*_Q_l_e_Q_P_I_t_O__*_6_m_

11-5 4
A manuscript entitled "Unsteady Planar Diffusion Flames: Ignition, Travel, Burnout" is to be presented in the

Microgravity Combustion Session at the AIAA 33rd Aerospace Sciences Meeting in Reno, NV, m January 1995.

Issues to be discussed include: (1) thm-Ilame modeling for equidiffusion and differing diffusivities (including

peripheral calculation of when the sufficiency condition for extinction, derived from a global second-order

irreversible Arrhenius-type model of the finite-rate chemic',d kinetics, is met); (2) results for finite-rate global

chemical kinetics; (3) flame quenching and possible water-vapor condensation, in proximity to the cold lateral walls

of the container: and (4) assignment of values to the dimensionless parameters arising in the parabolic

boun "dary/initial-value problem describing the travel of a planar diffusion flame. These parameters include the

Lewis-Semenov numbers for fuel vapor (hydrogen) and gaseous oxidizer (oxygen), the lh'st and second Damkohler

numbers, the isentropic coefficient, the dimensionless Arrhenius activation temperature, and the stoichiometrically

adjusted mass fractions for fuel vapor and gaseous oxidizer.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 7/98

PROJECT IDENTIFICATION: 963-15-00

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Fendell, F.E., Bush, W.B., Mitchell, J.A,, and Fink IV, S.F. Diffusion-flame burning of fuel-vapor pockets in air.

Combustion and Flame, vol. 98, 180-196 (1994).

11-5 5
Fundamental Study of Smoldering Combustion in Microgravity

PRINCIPALINVESTIGATOR:Prof. A. C. Fernandez-Pello University of California, Berkeley

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The overall project objective is to increase the fun "damental understanding and the prediction of smoldering

combustion under normal and microgravity conditions. This in turn will help the prevention and control of smolder

originated tires both, in normal gravity and in space-based environments. The specific objectives are to determine

the smolder characteristics of a polymeric porous combustible material (polyurethane loam), in a quiescent or

convective oxidizing environment, both at normal and micro-gravity. The final objective is a set of flight

experiments in a GAS Can facility in the Orbiter's cargo bay.

TASK DESCRfPTfON:

The project objectives are accomplished by conducting expertments on ground-based and space-based facilities, and

by developing theoretical m_lels of the process. The experiments are conducted with polyurethane foam as fuel

with mixtures of oxygen/nitrogen as oxidizer. Temperature at several locations of the sample are measured with

thermocouples; and the resulting temperature histories are used to obtain the smolder propagation velocity and

smolder reaction temperature, as a function of the oxidizer flow velocity and oxygen concentration. The

experimental results are used to verify and improve the theoretical models of smolder combustion. Experiments are

•also conducted to observe the potential transition from smoldering to flaming combustion, and to determine the

conditions and mechanisms leading to this transition.

TASK SIGNIFICANCE:

Smolder is important as both a tun "damental combustion problem, i.e., the propagation of a heterogeneous,

non-flaming, surface combustion reaction through a porous combustible material, and as a t-tre safety problem, i.e.,

the production of toxic compounds and the potential initiation of a t-tre through the transition to flaming. There is a

need for further understanding of the problem lor better prediction and control of smolder in both normal gravity and

microgravity. Furthermore, microgravity introduces additional questions about the transport of mass to and from

the reaction, and the transfer of heat from the reaction, that must be resolved in order to predict smolder behavior in

a space-based environment.

PROGRESSDURING FY 1994:

Task 1: Ignition Study of Opposed Smoldering

The main objective of the current research is to gain an understanding, and eventually a concrete theory, of the

ignition process in the smoldering of polyurethane. The immediate information we seek from the experiments are

two types of plots. The first of these is the Power vs. Time plot and the second is Minimum Energy vs Power.

Comparison of these curves with similar ones produced by Kitano in Japan show a number of differences. There is

an apparently strange behavior of our curves at the 115W power. Further testing must be done at this power level

to ensure our results are not due to experimental error. The same is true of the 100W power level. We are also

planning to do some testing at 160W and 40W. In addition, several experiments were run with no air or keeping

the air flow rate constant at 0.1mm/s rather than increasing it at a given time. No conclusions are yet available

from these experiments but further testing of this nature could prove vet 3, interesting. Finally, a Power vs. Time

curve was produced using a theoretical approach. The problem was modelled assuming one-dimensional heat

conduction in a semi-infinite medium with prescribed heat flux boundary condition.

Char is also being manufactured to be used in the next space shuttle mission. Larger char samples were sent to

NASA Lewis. Experiments are being run comparing the feasibility of replacing the char insulation behind the

heater with shredded FiberFrax insulation.

II-5 6
II. MSADProgramTasks-- Flight Research Discipline: Combustion Science

Task 2: Forward Smoldering

The building of the experimental apparatus has been completed. Experiments have been started to determine the

ignition characteristics. Currently, the configuration of the apparatus is as follows: the test section is of a

cylindrical geometry, 12cm in diameter and 30cm in length. The quality of the samples using this method is good

enough such that the use of liquid nitrogen to freeze the foam is not necessary. Attachments of flanged sections ot

20cm in length have been constructed (allowing for a total length of 50cm) for use in later phases of the project.

Species histories for HC, CO2, CO, and O2 are obtained by gas sampling. Temperature histories are gathered using

special prefabricated, fast response, probe thermocouples inserted into the centerline of the section every. 2cm along

it.s length. A nichrome wire sandwiched in-between ceramic honeycomb plates ignites the loam. The bottom of

the igniter is insulated with shredded Fiberfrax. Insulation below, which is a 2 micron pore size. pours metal plate

acting as a flow diffuser. Bottled, compressed air serves as oxidizer for the deterrmnation of the ignition

characteristics. Later phases will involve varying the oxygen concentration. The test samples are cut from a block

of loam using a core drill constructed from rolled sheet metal.

Tests have been run using varying igniter powers and air flow rates to determine their effect on smolder ignition.

Initial thermocouple data has indicated the possibility of two or three separate reaction fronts. We think these are

the pyrolysis front and a char oxidation front in addition to the smolder front. Experiments with lmm/s flow

velocity are "almost finished. We are now moving onto running experiments at 2mm/s flow velocity. Data for the

lmm/s flow velocity is being analyzed. We are looking to distinguish the pyrolysis, smolder propagation, and char

oxidation fronts.

Task 3: 2-D Smoldering with Transition to Flaming

Work has involved the modification of a wind tunnel such that a longer mixing chamber is incorporated for better

mixing of aggregate exhaust gases. Data for HC, CO, CO2, and 02 species histories are still being taken. An

array of 10 thermocouples have also been added at the gas/solid interlace in order to conlLrm and investigate the

possibility of transition to flaming at the fuel surface exposed to the ambient. Ever since the inclusion of a 2-D

matrix of 32 thermocouples embedded within the foam, experiments seem to indicate that dramatic increases in

temperature within the loam (which were previously believed to reflect actual transition to flaming) well precede

visual observations of flaming phenomena. The data acquisition system and software were modified to allow for

recorded temperature measurements at the solid/gas interlace.

Experiments for flow velocity conditions ranging from 0m/s (natural convection) to 2.5m/s have been run

incorporating shear interferometry to investigate flaming phenomena at the solid/gas interface. Analysis of the

additional data will hopefully verify the va.lidity of the two flaming regimes proposed in the Fall 1993 Western

States paper.

Visual observations and thermocouple histories seem to indicate that transition to flaming occurs in the char and not

at the interlace. Extremely localized temperature peaks (~1200C) occur in the char, well preceding flaming at the

interface. It is unclear as to whether these high temperatures peaks are the result of gas phase reactions, or very

exothermic, heterogeneous surface reactions. Other avenues of experimental investigation to better analyze this

phenomenon are being looked into such as, x-ray tomography, ultrasonic holography, and laser absorption imaging.

Data is still being an',dyzed and we are submitting an abstract to the 8th International Symposium on Transport

Phenomena in Combustion. S.F., U.S.A., July, 16-20, 1995. We have explored the use of ultra.,mnic imaging, and

the results are not too promising. The loam is opaque to sound frequencies on the order of 100kHz. Lower

tl"equencies on the order of 20kHz are being looked into. However, lower frequencies correstxmd to lower spaci',d

resolution. We are still collaborating with Prof. Miyasaka at Fukui University on this technique.

11-5 7
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 3/94 EXPIRATION: 3/97

BS Students: 0 BS Degrees: I) PROJECT IDENTIFICATION: 963-22-05-05

MS Students: 1 MS Degrees: 1 RESPONSIBLE CENTER: LeRC

PhD Students: 2 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Shultz. D.A., Matkowsky, B.J., Volpert. V.A. and Fernandez-Petlo. A.C. Propagation and extinction of forced opposed

t'low smolder waves. Combustion and Flame (in press). (1994L

Stocker, D.P., Olson, S., Torero, J.L. and Fernandez-Pello, A.C. Microgravity smoldering combustion on the USML-1

shuttle mission. ASME 1993 Winter Ann Meeting, New Orleans, LA. vol. 269. 99-110 (1993).

Torero. J.L., and Fernandez-Pello, A.C. Natural convection smolder of polyurethane loam. upward propagation. Fire

Safety Journal, (in press), (1994).

Torero, J.L., Fernandez-Pello, A.C. and Urban, D. Experimental observations of the effect of gravity changes on

smoldering combustion. AIAA Journal, vol. 35. 5, 991-996 (1994).

Presentations

Fernandez-Polio, A.C. "Smoldering combustion in microgravity: from ground to space shuttle experiments, "

Proceedings of the International Symposium on Aerospace and Fluid Sciences, Sendai, Japan, 243-273, 1993.

Fernandez-Pello, A.C, "Smoldering combustion in microgravity: from ground to space shuttle experiments." Lecture,

COSPAR "94 Conference, G1-Symposium on Microgravity Sciences: Results and Analysis of Recent Space Flights,

Hamburg, Germany, July 1994.

Torero, J.L. and Femandez-Pello, A.C. "Downward smoldering of polyurethane foam " Proceedings of the Fourth

International Symposium on Fire Safety (in presst 1994.

Tse, S.O.. Sanchez, C. and Fernandez-Polio, A.C. "Smoldering in the presence of a gas/solid interface and its transition to

flaming." 1993 Fall Meeting, Western States Section/The Combustion Institute, October 1993,

Tse. S.O.. Sanchez, C.G., Fujita, O. and Femandez-Pello. A.C. "Smoldering in the presence of a gas/solid interface and its

transition to flaming." Work-in-Progress Poster. Twenty-Fifth International Symposium on Combustion. lrvine. CA,

August 1994.

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II-5 8
Ignition and the Subsequent Transition to Flame Spread in Microgravity

PRINCIPALINVESTIGATOR: Dr. Takashi Kashiwagi National Institute of Standards and Technology (NIST)

CO-INVESTIGATORS:

Dr. Howard Baum

Dr. Kevin MacGrattan

National Institute of StandarcL_ and Technology (NIST)

National Institute of Standards and Technology (NIST)

TASK OBJECTIVE:

The objective is to conduct radiative ignition tollowed by transition to flame spread over various, different

combustible solid surfaces in microgravity in order to understand the transition mechanisms from the ignition to

subsequent flame spread, and to determine the effects of preheating, oxygen concentration, external flow velocity,

geometrical configuration, and sample materials on the transition and flame spread characteristics.

These results are needed for comparison with the numerically calculated data taking advantage of microgravity to

determine their accuracy and to examine the validity of the chemical and physical processes used in the calculations.

TASK DESCRIPTION:

The proposed space experiments will examine the effects on ignition and transition to flame spread of physical

parameters which include oxygen concentration (21-50% 02), preheated fuel temperature (ambient -100 C), fuel

thickness (thin/thick), fuel type (paper/pmma), geometrical configuration (including complex three-dimensional

geometry such as edges, open and closed corners), external flow velocity (0-5 cm/s), and flame conditions

(flaming/smoldering).

Proposed diagnostics includes a laser diode external radiant source, a digital data acquisition system, improved color

flame and char front imaging, infrared imaging of the fuel surface for a time-dependent surface temperature

distribution, and color shadowgraphy for flow+flame visualization. Gas species concentration measurements of 02

and CO, "Desirements" include PIV, FTIR, and 2-Color Pyrometry. Standard diagnostics include thermocouples

and experiment control verifications (flow, g level, radiant flux, etc.).

TASK SIGNIFICANCE:

For the first time, it is possible to study the transition from a radiative ignition to flame spread in the absence of

overwhelming buoyant convection. The elimination of natural convective flow in the microgravity experiment

simplifies both the formulation and subsequent computation of these time--dependent, three-dimensional problems

that include other complexities such as finite rate chemical kinetics in both the gas and solid.

PROGRESSDURING FY 1994:

There is no progress to report at this time as the project has not started yet.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 11/94 EXPIRATION: 11/98

PROJECT IDENTIFICATION: 963-15-OB

RESPONSIBLECENTER: LeRC

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II-5 9
II. MSADProgram Tasks -- Flight Research Discipline: Combustion Science

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Studies of Premixed Laminar and Turbulent Flames at Microgravity

PRINCIPALINVESTIGATOR:Prof. Paul D. Ronney University of Southern Ca.lifornia

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this work is to study the effects of gravity-induced buoyancy on the combustion limits of premixed

gas flames. The following/bur subtasks have been pursued:

1. Radiation effects on premixed gas flames.

2. Flame structure and stability at low Lewis number.

3. Flame propagation and extinction in cylindrical tubes.

4. Experunental simulation of combustion processes using autocatalytic chemical reactions.

TASK DESCRIPTION:

For task 1, we are studying the effects of the "addition of inert, radiant particles to gas mixtures to increase the

absorption coefficient of the gas. This enables us to study both the optically thin and optically thick radiation

regimes in a single experiment.

For task 2, we are studying flames in a variety of gas mixtures having low Lewis number (Le) in aircraft tests. The

goal of these studies is to determine under what conditions, if any, the instabilities which occur in low-Le mixtures

may lead to the development of stable, stationary spherical flames called "flame balls."

For task 3, we have conducted experiments at Earth gravity on flame propagation in vertical tubes of varying

diameter, at varying pressures and with mixtures having varying fuels, inert,s, and Le, and have measured the flame

propagation rates just inside the extinction limit. Since this quantity is predicted by most relevant theoretical

models, the relative importance of buoyancy, flame stretch, heat loss to the tube wall, radiation loss, etc., may be

assessed.

For task 4, we have introduced the use of aqueous autocatalytic propagating chemical fronts (in particular, the

arsenous acid-iodate system) for the experimental simulation of premixed combustion in nonuniform and unsteady

tlows. These fronts more nearly match the assumptions made by most relevant theoretical models that do gaseous

flames; for example, constant density, constant thermodynamic and transport processes, and no heat losses. We

have studied propagation in a Taylor-Couette (TC) flow, in the annulus between two rotating concentric cylinders,

and in capillary-wave (CW) flow in a thin layer of fluid in a vibrating dish.

TASK SIGNIFICANCE:

It is anticipated that the results of these studies will lead to an improved understanding of the thre hazards that may

exist in orbiting spacecraft and of ways to minimize these hazards. Furthermore, such studies may lead to an

improved understanding of the mechanisms of combustion limits in Earth-based combustion devices, which in turn

could lead to the development of cleaner and more efficient engines through the use of lean premixed combustors.

PROGRESSDURING FY1994:

For task (1), a radiometer preamplifier circuit was designed, built, and evaluated on real gaseous flames. It was used

on several KC- 135 flights in order to measure flame radiation from flame-balls. These tests were particularly

important tot the hydrogen-air flames which emit only weak, but fundamentally importanL thermal radiation that is

difficult to detect without preamplification of the radiometer signal.

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I1-6 0
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

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For task (2), six weeks of low-gravity flight tests were pertormed on NASA's KC-135 research aircralt. A large

amount of engineering data was obtained; no new scientific phenomena was seen, nor were any expected because :dl

test mixtures had been studied in previous flight experiments. Several excellent examples of the "sudden

propagation" phenomena_ seen in methane-oxygen-sulfur hexafluoride mixtures and thought to be caused by gas

radiation, were observed. The most important lessons learned which will affect the spaceflight expertment are 1) the

possibility of etching of/'used silica windows during spaceflight experiments due to corrosive combustion

by-products0 2) the difficulties in obtaining accurate gas mixtures based on partial pressures and measured by gas

chromatography, 3) the radiometers worked as expected but for hydrogen-air mixtures preamplification is required. 4)

operational confidence in the spaceflight hardware can be enhanced by checking their operation of them during

evacuation, chamber filling, and chamber lighting, and 5) the Xybion cameras are able to detect the combustion

phenomena, however, they can be damaged by intense chamber lighting.

In addition to the buildup of the radiometer preamplifier circuit, several other hardware improvements were made. A

new partial pressure gas mixing system and "algorithm was built and tested in the laboratory. An improved spark

energy measurement system built around a digital oscilloscope and data processing system was developed. A

computerized PC-based image processing system wave was implemented. One preliminary finding is that rnany of

the tests run in the KC-135 have resulted in overexposed images. A workstation for conducting flame-ball

modeling calculations was delivered, and a one-dimensional, unsteady flame code employing detailed chemic_d and

transport sub-models, developed by B. Rogg at Cambridge University, was obtmned. This system will form the

basis of the flame-ball modeling calculations to be used for comparison with the spaceflight experimental results.

The PI participated in the first meeting of the joint US/Japan Microgravity Combustion Coordinating Group. The

PI proposed to perform a set of flame-ball experiments in the Hokkaido 10 second drop facility to supplement lhe

spaceflight test matrix.

The PI also collaborated in a study with the Aerospace Corporation regarding the use of lasers lot ignition.

Minimum ignition energies of methane-art mixtures at 1 atm initial pressure as a function of fuel-air ratio were

measured and compared to prior spark ignition and numerical modeling. The results suggest a criticai role of the

size of the energy deposition region, and the potential for significantly reduced minimum ignition energies compared

to classical experiments if the size of the deposition region is made sufficiently small.

For task (3), to complement his current study of combustible mixtures with low Lewis number, the PI participated

in a study of flame propagation at high Lewis number in tubes with Dr. Howard Pearlman, a NRC postdoctoral

research associate at NASA Lewis. Theory predicts at high Lewis number, pulsating and traveling-wave

instabilities should occur. The experiments have shown spiral-wave flame fronts in addition to the predicted modes.

None of these modes have been conclusively observed experimentally in previous works, probably because these

experiments employed more advanced diagnostics and mixtures with higher Lewis numbers than any previous work

of its type.

For task (4), plans were made for the study of chemically reacting fronts responding to hydrodynamic strain. A

Taylor four-roll mill, where the strain rate is determined by the rate of rotation of the rollers has been constructed.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 9 BS Degrees: 9

MS Students: 2 MS Degrees: 2

PhD Students: 2 PhD Degrees: 1

TASK INITIATION: 3/91 EXPIRATION: 12/94

PROJECT IDENTIFICATION: 962-22-05-06

RESPONSIBLE CENTER: LcRC

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1I-6 1
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

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BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Haslam. B,D. and Ronney. P.D. Fractal properties of propagating fronts in a strongly stirred fluid. Submitted to Physics

of Fluids, (1995).

Lozinski. D., Buckmaster, J.D. and Ronney, P.D. Absolute flammability lhnits and flame balls in optically thick

mixtures. Combustion and Flame, vol, 97, 301-316 (1994).

Pearlman, H.G. and Ronney, P.D. Self-organized spiral and circular waves in premixed gas flames. Journal of Chemical

Physics. w)l. 101, 2632-2633 (1994).

Pearlman, H.G. and Ronney, P.D. Near-limit behavior of high Lewis-number premixed t-lames in tubes at normal and low

gravity. Physics of Fluids. vol.6. 4009-4018 (1994_.

Runney, P.D. Laser versus conventional ignition of flames. Optical Engineering, vol. 33, 510-521 f1994).

Ronney. P.D., Whaling, K.N., Abbud-Madrid. A.. Gatto. J.L., and Pisowicz. VL. Stationary premixed t'lames in spherical

and cylindrical geometries. AIAA Journal, vol. 32. 569-577 (1994).

Zhu, J.Y. and Ronney, P.D. Simulation of front propagation at large non-dimensional flow disturbance intensities.

Combustion Science and Technology (in press), vol. 100. 183-201 (1994).

Books

Ronney, P.D. "Some open issues in premixed turbulent combustion." in "Mathematical Modeling in Combustion and its

Interaction with Numerical Computation." Edited by: J.D. Buckmaster and T. Takeno Springer-Verlag, in press, 1995.

Presentations

Pearlman, H.G.and Ronney. P.D. "Near-limit behavior of high Lewis-number premixed flames in tubes at normal and low

gravity." Spring Technical Meeting, Combustion Institute, Central States Section, Madison. WI, June 6-7, 1994.

Ronney, P.D. "Requirements design review: structure of flame balls at low Lewis-number (SOFBALL)." NASA Lewis

Research Center, Cleveland, OH, Oct. 14, 1993.

Ronney, P.D., "Combustion at zero-gravity," Dept. of Mechanical Engineering." University of Southern California, Los

Angeles, CA, November 1993.

Ronney, P.D. "Preliminary design review: structure of flame balls at low Lewis-number (SOFBALL)." NASA Lewis

Research Center, Cleveland. OH. May 17. 1994.

Ronney. P.D. "Propagation and extinction mechanisms of premixed turbulent flames." Joint U.S./Japan Workshop on

Mathematical Modeling in Combustion and its Interaction with Numerical Computation. Kaapa, HI, July 25-29. 1994.

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I1--6 2
Ignition and Flame Spread qf Liquid Fuel Pools

PRINCIPALINVESTIGATOR: Dr. How_rd D. Ross NASA Lewis Research Center (LeRC)

CO-INVESTIGATORS:

Prof. W.A. Sirignano

Dr. F.J. Miller

University of California, Irvine

Case Western Reserve University

TASK OBJECTIVE:

For flame spread over liquid fuel pools, the existing literature suggests three gravitational influences: (a)

liquid-phase buoyant convection, delaying ignition and assisting flame spread; (b) hydrostatic pressure variation, due

to variation in the liquid pool height caused by thermocapillary-induced convection; and (c) gas-phase buoyant

convection in the opposite direction to the liquid-phase motion. No current model accounts for all three influences.

In tact. prior to this work, there was no ability to determine whether ignition delay times and flame spread rates

would be greater or lesser in low gravity.

Flame spread over liquid fuel pools is most commonly characterized by the relationship of the initial pool

temperature to the fuel's idealized flash point temperature, with tour or five separate characteristic regimes having

been identified. In the uniform spread regime, control has been attributed to (a) gas-phase conduction and radiation,

(b) gas-phase conduction only, (c) gas-phase convection and liquid conduction, and most recently (d) liquid

convection ahead of the flame. Suggestions were made that the liquid convection was owed to both buoyancy and

thermocapiUarity. In the pulsating regime, complicated flow structures have been observed in both the gas and

liquid phases, with circulation around several centers; these flows were attributed to combined thermocapillary and

buoyant effects.

TASK DESCRIPTION:

The approach we have taken to resolving the importance of buoyancy for these flames is (a) normal gravity

experiments with advanced diagnostics, (b) microgravity experiments, and (c) numerical modeling at arbitrary

gravitational levels.

TASK SIGNIFICANCE:

Of special interest to this work is the determination of whether, and under what conditions, pulsating spread can and

will occur in microgravity in the absence of buoyant flows in both phases. One possible mechanism tot pulsating

spread in microgravity is if the "premixed gasdiffusive burning" pulsations are due to periodicity between gas-phase

conductive and liquid-phase convective control. A second possibility, which will be determined by these

investigations, is whether pulsations may be induced in low gravity by the presence of slow, forced, gas-phase

flow.

PROGRESSDURING FY 1994:

During FY1994 the foremost accomplishment was the completion of the flight hardware for the first sounding

rocket flight. Early in FY1994 the final fabrication of parts was completed and assembly continued throughout the

spring. Component and assembly vibration tests were successfully completed at Lewis and two full normal-gravity

combustion tests were carried out in the flight hardware. In both tests the hardware performed well, though an

initial switch setting prevented good science data from being obtained in the first test, and a misconnected cable and

poorly lbcused camera plagued the second test. All of these problems were traced to lapses in procedures, and steps

were taken to improve the assembly and test practices. The hardware underwent another round of vibration testing at

Wallops Island, and sequence testing and spin balancing were performed. The hardware is currently underway to

White Sands Missile range for a scheduled November 22nd launch, the first Lewis sounding rocket experiment in

nearly 30 years.

ii--63
lI. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

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In order to obtain 1-g data for comparison purposes, and to spare the flight hardware having to undergo multiple

combustion tests, a full breadboard version of SAL was designed and constructed out of (mostly) spare parts. Using

this apparatus the following tests were performed.

• Using a beam splitter, video mixer, and long local length lenses we captured some simultaneous close-up gas and

liquid phase schlieren views and visible flame views of flame spread in the unitorm regime. A slight preheating of

the gas was visible in the schlieren view (about 1 mm), but any liquid-phase view was generally swamped by

temperature gradients caused by surface evaporation. Thus, it appears for this case that the preheating occurs

extremely close to the surface and the flame leading edge (on the order of lmm), which agrees well with theoretical

modelling but not with the previous interferometry work by others.

• We conducted several tests using a Kodak Ektapro High Speed video camera to capture PIV images at 500

frames/sec. Floating particles were used to record the surface movement. The video clearly indicates liquid-phase

movement ahead of the flame (several mm)even in the highly uniform spread region (1-propanol, 22-23 C).

However, no evidence has been round that the liquid phase accelerates to a speed taster than the flame front.

• We successfully used the Object Tracking Workstation system to track surface particles ahead of a 1 -propanol

flame in the uniform regime. The analysis, which involved data taken with the high speed video camera,

corroborates and significantly strengthens preliminary data taken last summer which indicate surface flow ahead of

the flame. The data is presented in graphs which show flame and particle location vs. time, and the particles are

clearly seen to move 3-4 mm ahead of the flame, though the flame normally does overtake them.

• For pulsating spread, the high-speed video showed that the flame never caught the flow head. We also obtained

good views of the vortex forming in the bulk liquid.

We continued working on improvements to the rainbow schlieren deflectometry (RSD) technique which will benefit

all projects employing this diagnostic. We completed programs to make arbitrary cartesian, symmetric, gray scale,

and single color filters, as well improved the optimization program to handle filters of any size and type. A NASA

TM is planned to describe the new filter generation process and programs. We also performed the lirst quantitative

comparison of RSD derived temperatures with temperatures measured independently. This was done for a stably

stratified liquid layer and showed a disagreement of 0.4°C when the schlieren data was integrated over a distance of

10 mm. Work continues to improve this.

Development of a code used to animate our numerical results was largely completed. Using these animations we

were able to uncover some errors in the flame spread code, notably a nonconservauon of mass whenever the grid

shifted. Finding such an error would have been nearly impossible using only still images, but the animations

showed it clearly in the flame motion. This error and some others have now been corrected. However, a large

gas-phase recirculation cell that we also discovered, and has been traced to numerical problems at the top boundary

of the domain, still remains. Fortunately, it does not seem to affect the "'calculated flame spread rate. Particle

tracking was added to the animation code, to mimic the experimental PIV data, and mock RSD and interferometry

was also performed. Excellent agreement between the calculated and measured RSD views was obtained regarding

vortex size and location, while differences in the calculated and measured (by others) interferometry views remain.

Some differences in the surface particle trajectories still exist between the code and the experiments as well.

The Zero Gravity Facility returned to operation in FY94 and many experiments were conducted using the old

hardware with some improvements such as better flow control, and a top view video camera. The drops showed

successful ignition and initial spread over 1-butanol at opposed flow rates between 10 and 20 cm/s, which is the

range chosen for the sounding rocket flights. We also did a few experiments with propanol which showed flame

spread with opposed flow.

A low-speed wind tunnel that allows operation between 5 and 200 cm/s was set up and flow profiles were measured

for several speeds and locations. Flow visualization w_s also conducted with dummy fuel trays in place. This

tunnel will allow testing of flame spread over liquid and solids in the presence of opposed or co-current flow at

normal gravity.

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II--6 4,
II. MSAD Program Tasks -- Flight Research Discipline: Combuslion Science

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STUDENTS FUNDED UNDER RESEARCH:

BS Students: 2 BS Degrees: 0

MS Students: 0 MS Degrees: 0

PhD Students: 1 PhD Degrees: I

TASK INITIATION: 2/91 EXPIRATION: 2/97

PROJECT IDENTIFICATION: 962-22-05-07

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Miller, FJ., Ross, H.D., and Schiller, D.N. "Temperature field during flame spread over alcohol pools: Measurements and

modelling." Accepted at the Eastern States Section of the Combustion Institute Fall Technical Meeting, Clearwater Beach.

FL, 1994.

Miller, F.J., Ross, H.D.. and Schiller. DN. "Rainbow schlieren deflectometry of flame spread over liquid pools: A

comparison of experimental and numerical results." Poster at the Twenty-Fifth International Symposium on Combustion,

Irvine. CA, I994.

I1--6 5
IT. MSAD Program Tasks -- Flight Research Discipline: Combuslion Science

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Combustion of Solid Fuel in Very Low Speed Oxygen Streams

PRINCIPALINVESTIGATOR: Prof. James S. T'ien Case Western Reserve University

CO-INVESTIGATORS:

K.R. Sacksteder

P.V. Ferkul

NASA Lewis Research Center (LeRC)

National Research Council

TASK OBJECTIVE:

The objectives are to:

1. Enhance the understanding of flame spreading above solid-fuel surfaces through a systematic investigation in the

low-speed, forced and buoyant flow regimes.

2. Determine the mechanisms that induce flammability limits of flames over solid surfaces in low-speed flows.

3. Resolve the structure of flames spreading in low-speed flows through a characterization of the velocity,

temperature and selected-species fields in their vicinity.

TASK DESCRIPTION:

This task consists of the development and flight of a space-based experiment, the continued pursuit of ground-based

results in drop towers and aircraft experiments, and the continued development of a comprehensive predictive model

of concurrent-flow flame spreading.

The flight experiment is to be accomplished in three phases. An experiment to be conducted in a Glovebox Facility

is to provide insight into global flame characteristics of thin and thick fuels. In the second phase, thin fuels are to

be burned as they are dispensed from a continuous supply in such a way that the flame is fixed in space relative to

the test apparatus. In this way, detailed diagnostic measurements are greatly simplified and transient flame behavior

can be observed as the test conditions are slowly varied. In the third phase thick fuels will be burned to address the

effect of transverse heat conduction into the fuel, yet with flames spreading slowly enough that the same diagnostic

measurements can be made.

The ground-based experimental program consists of observations of flame spreading in partial gravity environments

(lirst attempted as part of this program), the ignition behavior of flames over thin and thick solid fuels in

microgravity forced flows, and the implementation of temperature, velocity and species concentration measurement

systems.

The model development consists of integrating a fully elliptical fluid mechanics formulation with surface and gas

phase radiative interactions in a transient model that attempts to predict the behavior of the selected experimental

test fuels in concurrent-flow burning.

TASK SIGNIFICANCE:

In normal gravity, buoyant air motion in Ilames is at least 20 to 30 cm/sec. Flame spreading mechanisms that are

present only in lower flow velocities, such as spacecraft air-ventilation currents, cannot, therefore, be studied in

normal gravity. This research seeks to contribute to fundamental combustion science, and to improve the basis for

engineering improved spacecrati t_e safety.

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I1--6 6
II. MSADProgramTasks-- Flight Research Discipline: Combustion Science

! * | I * i |*| J*l *l**l! i, *a | * | | * * * I ! * _ * | | | I * ! * i ! *|, I, *, i * ! i., ! ! a i i *| i,, u *. i * |,, i,,,, * |, * i i | | * e i i. i, i i Ill ia i i * i i * * * | * i n* i, n, * * * i * *,, * |1, *, iii; *, i I !, i * *, * ¢,, g * tg, i i * i i *,, * P*, *, i ** i| * i | *, i * i ** i_ * i, *,, _ i, * * i ** _| * i i * _ * * i i _ * i i _, i | _ * | ¢ _,,, i *,, i i i* *, *,,, * _1

PROGRESSDURING FY 1994:

This is a new task in Fiscal Year 1994 beginning with the award of a new flight experiment project entitled,

"Combustion of Solid Fuel in Very Low Speed Oxygen Streams," under NRA-93-OLMSA-I, "Microgravity

Combustion Science: Research and Flight Experiment Opportunities."

Since the transition to the flight program, this task has achieved the following major accomplishments:

1. The numerical formulation of the theoretical model of concurrent flow flame spreading has been modified to

permit the simulation of purely buoyant flows. This model has been used to predict flammability limits and flame

spreading behavior over a range of oxygen concentrations and gravitational acceleration levels, predicting a

flammability limit in air (21% oxygen) of 0.0003g.

2. The numerical formulation of the theoretical model of concurrent flow flame spreading has been modified to

simulate the gas phase radiation from flames in low speed flows.

3. The Forced Flow Flamespread Test glovebox experiment (FFFT) was successfully reviewed in a peer-reviewed

Science competition, and has been manifested aboard the USMP-3 mission, and is a candidate for flight aboard the

MIR Space Station. An aircraft glovebox facility was prepared for testing of the FFFT in a liee-float mode, unique

among glovebox experiments, in which observations were made of the ignition of both thin and thick fuel sample

candidates. The final design of the FFFT was completed, including the addition of a novel imaging system for

in-situ, real-time velocity measurements incorporated into the video data from the experiment.

4. Experiment technology for the newly awarded flight experiment has been developed to permit the continuous

dispensing of thin fuel into an established flame in low-speed forced flows in microgravity. The device consists of

rolls of 7 cm wide, thin-fuel strips edged with a conductive foil to quench the fuel edge and a small combustion

tunnel through which the fuel strip is pulled. An optical device detects the burnout front of the fuel where the flame

is stabilized and controls the fuel feed rate. The gas flow is based upon the successful design of the Forced Flow

Flamespread Test glovebox experiment technology. This device is designed to be integrated into the existing

aircrall facility which was designed originally for used in purely buoyant flow flame spread studies, providing quick.

low-cost access to reduced gravity testing of this new technology, and providing quick, low-cost access to rainbow

schlieren measurements of forced-flow flame spreading experiments.

5. A series of experiments were completed in the NASA KC-135 aircraI't providing the first stereo (3-dimensional)

photographs of microgravity combustion flames; specifically downward flame spreading expermaents in partial

gravity environments. This imaging technology is a candidate for the newly awarded flight experiment.

6. A new set of experiments were completed in the 5 second drop tower providing observauons of concurrent flow

flame spread ignition processes using the flammable sample translation device developed in this program. These

tests provided a direct comparison of hot-wire ignition techniques with and without a chemical promoter, and some

improved observations of the beginnings of transitions toward spreading.

7. A new formulation of traditional methods for correlating opposed flow flame spreading expertmental results was

derived using the results of the partial gravity flame spreading tests. This new formulation for the first ttme

correlates reduced and mircrogravity results with normal gravity results, accounting for radiative losses from

low-speed flames.

8. A new concept for the research of partial gravity flame spreading was identified: using the Canadian Large Motion

Isolation Machine (LMIM) reprogrammed to a set point of, for example, 0.001 g instead of the conventional set

point of 0.0g. This device may permit observations of flame spreading in steady, milli-g environments, which may

be the transition region between high-speed and low-speed buoyant flow regimes.

11--6 7
II. MSAD Program Tasks -- Flight Research Discipline: Combustion Science

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 1 MS Degrees: 3

PhD Students: 1 PhD Degrees: 2

TASKINITIATION: 2/94 EXPIRATION: 2/99

PROJECTIDENTIFICATION:962-22-05-40

NASA CONTRACTNO.:NAG3-1046

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

FerkuL P.V. and T'ien. J.S. A model of low-speed concurrent flow flame spread over a thin fuel. Combustion Science and

Technology, w_l. 99. 345-370. (1994).

Presentations

Ching-Biau. Jiang and T'ien. James S. "Numerical computation of flame spread over a thin solid in forced concurrent flow

with gas-phase radiation." accepted for presentation at the Eastern States Section Meeting of the Combustion Institute

(December 1994).

/iang, C., T'ien, J.S. and Ferkul. P.V. "Numerical computation of buoyant upward flame spread and extinction over a thin

solid in reduced gravity." presented to the Central States Section Meeting of the Combustion Institute. Madison

Wisconsin, June 5-7, 1994.

Sacksteder, K.R. and T'ien, J.S. "Buoyant downward diffusion tlame spread and extinction in partial gravity

accelerations." Presented at the Twenty-Fifth Symposium (International) on Combustion, The Combustion Institute.

1994.

Sacksteder, K.R. and T'ien J.S. "Buoyant downward diffusion flame spread and extinction in partial gravity accelerations."

presented to the Micro-Gravity Measurements Group Meeting #13, Montreal Quebec Canada, September 1994.

11-68
Droplet Combustion Experiment

PRINCIPALINVESTIGATOR:ProL Forman A. Williams University of Calilornia, San Diego

CO-INVESTIGATORS:

Prof. F.L. Drver Princeton University

TASK OBJECTIVE:

The objective of this research is to provide scientific support (in collaboration with Professor F. Dryer of Princeton

University) for a droplet burning experiment to be performed on-board a space platform. This support will include

perforrnance of theoretical analyses relevant to the experiments, execution of drop-tower experiments to acqutre

additional data, analysis of experimental data obtained in ground-based experiments, and identification of test

conditions for experiments in space.

TASK DESCRIPTION:

The objectives stated above will be pursued through the use of the NASA LeRC 2.2-Second Drop Tower with

measurements made on heptane and methanol burning in atmospheres of normal air and in diluted atmospheres and

through the analysis of data from this tower, and also the 5-Second Drop Tower with these fuels as well as decane.

The data will be analyzed for droplet diameter and extinction diameter by use of high-precision analysis systems.

Flame diameters "also will be obtained by suitable digital tmage analysis procedures.

The theoretical approach will employ asymptotic methods to relate observed extinction conditions to elementary

rate parameters. Treatment of the data by use of theory will help identify experiments that need to be done in space.

Additional experiments will also be performed to address the effects of relative droplet-gas convection on burning

rates. In the theoretical part of the project, a spherosymmetnc, time-dependent, finite element-based numerical

model with detailed gas phase kinetics, and variable property effects will be extended to study the effecLs of soot

formation in droplet burning. Extension of the existing one-dimensional code to two-dimensional axisymmetric

geometry, will be evaluated.

TASK SIGNIFICANCE:

The overall purpose of the research is to achieve fundamental advances in the science of droplet combustion, in

particular, unsteady liquid and gas phenomenon, and extinction chemistry, of normal alkanes and alcohols are

investigated.

PROGRESSDURINGFY 1994:

Theoretical Studies at UC-San Diego

Analytical modeling on the structure and extinclaon of quasi-steady, spherically symmetric diffusion flames around

methanol droplet corresponding to two, three, and tour-step reduced mechanisms have been already completed. For

methanol droplets, the equilibrium of water-gas shift is very good so that extinction diameters obtained from the

two and three-step analysis are almost the same. The asymptotic analysis corresponding to the tour-step

mechanism, obtained by relaxing the H atom steady-state assumption, gives extinction diameters 50% smaller than

those of the two and three-step analyses. Comparison between UCSD asymptotic results and the numerical

calculations performed at Princeton show significant disagreement with the asymptotics predicting extinction

diaIneters roughly one order magnitude smaller. When water absorption is included and an assumption of 40% water

at extinction is included, the asymptotic results agree well with the numerics lor methanol burned in air at 1 atm.

However, at this stage the amount of water absorption at extraction must be guessed so asymptotic analysis of

tune-dependent water absorption problem has been started. Also, pool burning experiments to gain better

understanding of the water absorption is underway.

I i i i i I I I I I I I I II i i i i i i i i i i ii i i ii i i i I i i i ii Ii i i I i i i I I I I i I Ii i i i i i i i i i i ii i i i i i I I i i i I Ii i ii i I I I II I i II I I I I i i I II I I ii iII I I i i i i i II III I I I I i i i i I I ii i iI I i i i i i i i Ii ii I i i i i i i IIi i i iI iii ii i i i i i ii i i i i i ii i II II i i i ii i ii i i i Ii Iii ii I Itl i i ii i ii i I I I I I I I I n I ii i i i i ii i i i i ii i i

11-69
II. MSADProgramTasks-- Flight Research Discipline: Combustion Science

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Numerical and Experimental Studies at Princeton

Methanol an0 N-HcP_ln¢ Droplet Vaporization and Combustion Modelim,

A report describing m detail the numerical modeling which was performed to develop the test envelopes for the

second flight test matrix entitled, "Theoretical Basis tor Estimating Test Times and Conditions tor Drop Tower and

Space-Based Droplet Burning Expenment.s with Methanol and N-Heptane" was issued as Princeton University

MAE Report No. 1999.

Numcriq_ Modeling ot the Comb0sti0n of Methanol/Water Mix_:0r¢ Droplets

Extensive numerical calculations for methanol/water mixture droplets of 1-5 nun diameter in air were performed.

These resulLs will be compared with those obtained using the FSDC glove box expertments (USML-2) as well as

drop tower testing which will be conducted this fall.

Development of 2-D Dropl¢¢ Combustion Model

Progress has been made in developing a droplet combustion/vaporization finite-element model. As a test case,

boundary conditions tbr the case of pure vaporization involving two species (methanol/water) with tLxed surface

temperature has been implemented into the FORTRAN program. This program is currently being debugged and is

expected to run shortly.

Other

Extensive tests were carried out for n-heptane burning in O2/He environments at the NASA Lewis 5-second drop

tower, These tests cover the proposed DCE first flight test matrix. New and important results on OH-imaging of

the droplet flames were accomplished using UV cameras. The test results are being analyzed and the results will be

presented at the 3rd microgravity combustion workshop,

During this reporting period a successful RDR/PDR for the Droplet Combustion Experiment (DCE) was completed

in collaboration with the NASA personnel.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 3/91 EXPIRATION: 3/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-22-05-08

MS Students: 0 MS Degrees: 0 RESPONSIBLECENTER: LeRC

PhD Students: 3 PhD Degrees: 3

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Card, J.M. Asymptotic analysis for the burning of n-heptane droplets using a four-step reduced mechanism. Combustion

and Flame. (t993).

NASA Tech Briefs

Dryer, F.L. Computational/experimental studies of isolated, single component droplet combustion. Second International

Microgravity Combustion Workshop, NASA Conference Publication 10113. NASA Tech Brief, 291-196 (1993).

Williams, F.A. Studies of droplet burning and extinction, Second International Microgravity Combustion Workshop,

NASA Conference Publication 10113. NASA Tech Brief. 283-290 (1993).

Presentations

Choi, M.Y., Dryer, F.L., Green. G.J. and Sangiovanni, J.J.

AIAA Paper No. 93-0823, January 1993.

"Soot agglomeration in isolated, free droplet combustion."

Marchese, A.J. and Dryer, F.L. "Computational modeling of transient methanol droplet vaporization." presented at the

Easter States Section of the Combustion Institute Meeting, October 1993.

I aI Ill Ill Ill nell Ill III llll Jlllll I II I I l I II Ill I el elil lllll I el I I I It I It lII I I I I I tl It I Ill el I I I I I l I l I II I I I I t I I II eI I I I I IIt III I Illl Ill I lI It I I I I I I I eI It I II l tl I I I I I I l II l IIII I I I I It lI I I I I l I I III IIt I I It Ill l Ill II t I I I I I l I t I I I Il II l I I I I al I I tit Ill II I It I III I11111 It I

il-7 0
Marchese. A.J. and Dryer. F.L. "Transient modeling of the combustion of bi-component liquid droplets: methanol/water

mixtures." presented at the Easter States Section of the Combustion Institure Meeting. 1994.

Marchese. A.J.. Dryer. F.L. and Choi. M.Y, "Theoretical basis for estimated test times and conditions for drop tower and

space-based droplet burning experiments with methanol and n-heptane." MAE Report No. 1999, Princeton University.

August 1994.

Zhang, B.L., Card, J.M. and Williams, F.A. "Application of rate ratio asymptotics t_ the prediction of extinction fc_r

methanol droplet combustion." Western States Section of the Combustion Institute, March 1994.
lI. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

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Surface Controlled Phenomena

PRINCIPAL INVESTIGATOR: Prof. Robert E. Apfel Yale University

CO-INVESTIGATORS:

R.G. Holt

Yuren Tian

Jet Propulsion Laboratory

Yale University

TASK OBJECTIVE:

The goals of this research are to investigate the rheological properties of surfactant-bearing liquid drops. By

comparing experimental results in the ideal environment of the Spacelab to our theory for spherical equilibrium

drops, we can validate the model. We can then synthesize a generic theory which can handle arbitrary acoustic fields

and static deformations, in order to have a technique for studying static and dynamic surface properties for

surfactant-bearing drops which can be successfully applied in 1-g experiments.

TASK DESCRIPTION:

Single liquid drops are introduced into the center node of an acoustic standing wave in DPM's Near-Ambient

Chamber. They are allowed to reach quiescent equilibrium. Then, shape oscillations about either a spherical or a

spheroidal equilibrium shape are excited - either by a momentary increase and release of the z-axis acoustic pressure

or by a periodic modulation of that pressure. The resulting oscillations are recorded on video tape and cin6 film for

later analysis.

Three sample materials will be investigated on USML-2: triply distilled water, water with small amounts of Triton

X-100 or bovine serum albumin at five different concentrations. The additives provide contrasting time scales:

Triton X-100 is a nonionic fast-sorbing surfactant while BSA is sorption-inhibited. A range of drop sizes from 4 to

12 cc will be investigated for each of concentration.

TASK SIGNIFICANCE:

The/light experimental data will be used to validate the theory which describes drop shape-oscillations as a thnction

of various surface parameters. These parameters will be obtained in microgravity from drops oscillating about a

spherical equilibrium shape as well as about an acoustically induced oblate shape. By comparing the differences in

the natural frequency and "damping constant tor these oscillations, the theory, and experimental techniques can be

used to perform measurements of the surface properties on the ground. Theoretical development and ground-based

experiments to support the microgravity work are also performed.

PROGRESSDURINGFY 1994:

Ground-based work, primarily in preparation for the USML-2 mission has focused on assuring ourselves that a) the

improved DPM will work up to expectations, b) the crew will be well trained for the mission, and c) the quality of

the science and the ultimate science return will be maximized.

In preparation for USML-2, tests have been performed to determine an optimal tip configuration for drop

deployment; the best of the ground based designs were tested in KC-135 flights as well. Tests have been performed

on whether the flexible tubing used to transport fluids for forming drops can produce bubbles. Both levitated and

suspended samples are being used to study spurious sample rotation of the type observed on USML-1; from our

understanding techniques for compensation are being developed.

We have designed a computer simulation of drop dynamics that can be used in training the USML-2 crew. It has

been delivered to the Payload Crew Training Complex at MSFC.

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11-7 2
II. MSADProgramTasks-- Flight Research Discipline: Fluid Physics

_B_H_t_l_I_¢_l¢IliI_I_"lI_II_i_|_I_ii_H_"t_"_|_"I_II_m_¢*_¢I_II_H_iH_|_|_H_o_||i_ ml|¢ll0111111¢|m|,,Hmgllm mllll_ll,011¢,1011HHItmmlll,llm mlm. H llll

Ten papers covering the experimental, analytical, and computational studies into the rheology of surfaces covering

the work done in this fiscal year will be submitted within the calendar year. Experimental measurements of surface

tension from the static shape of a very small levitated drop compare well with theoretical predictions. Oscillating

drop experiments analogous to those of USML-1 and USML-2 have been carried out on the ground. An automated

system for reducing the video tmage of a drop to half a dozen parameters is now processing three frames a minute.

The deformation on both static and oscillating drops due to the levitating and oscillation-driving acoustic field has

been studied using a boundary-integral technique. The interaction of speakers in various configurations and the

resulting torques have been studied with levitated and suspended samples.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 3 BS Degrees: 3

MS Students: 2 MS Degrees: 0

PhD Students: 3 PhD Degrees: 1

TASK INITIATION: 2/90 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 963-24-04-03

RESPONSIBLE CENTER: JPL

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11-7 3
[I. MSAD Program Tasks -- Right Research Discipline: Fluid Physics

,'tlS,lO|*a*l'O*'ltl,,|lt*li*Jllll*o,|alillllllOll|llOSll*,l_,,*,l,l,* Jl* J,tl|*l!'''lll_H "l_i,,|l*|ll,,,,,,*'l'l H tlI*,O*,III,,OII*,O*II,H **''*,',H _*_*_*i_*_|_|_H_i*_I_a_i_*¢_|||_|_*_|_H_o_s_o_|_||_|_|t

Critical Viscosity of Xenon

PRINCIPALINVESTIGATOR:Dr. Robert F. Berg National Institute of Standards and Technology (NIST)

CO-INVESTIGATORS:

Dr. Michael R. Moldover Nationa.l Institute of Standards and Technology (NIST)

TASK OBJECTIVE:

The objective of the experiment is to produce archival viscosity data on xenon that is closer to its liquid-vapor fluid

critical point than is possible in 1-g.

TASK DESCRIPTION:

1. Develop a low frequency, low shear rate viscometer with pK temperature control near room temperature. It will

be of an electrostatically driven micro-flexure design;

2. Characterize vibration isolation sutt_cient to approach the criticat temperature to within 300 #K while measuring

viscosities to 0.5% precision;

3. Load xenon sample to within 0.3% of the critical density;

4. Choose sample geometry and do heat transfer analysis to establish expected thermal gradients and thermal

equilibration times realistic for a Space Shuttle flight timeline;

5. Involve critical point dynamics theorists in data analysis before and after flight.

TASK SIGNIFICANCE:

The data will provide complementary results with Critical Fluid Light Scattering Experiment (CFLSE) to test the

mode-coupling theory of critical phenomena and provide guidance to renormalization group theory development on

dynamic critical-point fluid behavior.

PROGRESS DURING FY 1994:

Oscillator calibration:

We developed a novel, accurate calibration procedure for the oscillating screen viscometer. This procedure, which

makes use of the viscometer's wide bandwidth and hydrodynamic similarity, "allows the viscometer to be

sell:calibrating. To demonstrate the validity of this procedure we measured the oscillator's transfer function under a

wide variety of conditions. We obtained data using CO, at temperatures spanning a temperature range of 35 K and

densities varying by a t_tctor of 165, thereby encountering viscosity variations as great as 50%. In con(fast the

flight experiment will be performed over a temperature range of 29K and at only a single density, and the viscosity

is expected to change by less than 40%. The measurements showed that the viscometer's behavior is fully

consistent with the use of hydrodynamic similarity for calibration.

Cell loading and viscometer testing near Tc:

The same cell used for the CO: tests was later tilled with xenon to within 0.2% of its critical density by use of a

carefully characterized filling procedure. This is better than the required accuracy of 0.3%. The critical temperature

Tc was then located to a precision of better than 1 mK by observing the appearance and disappearance of the

liquid-vapor meniscus. This is better than the 10 mK precision required to choose the value of the reference resistor

of the cell's temperature bridge.

Viscosity measurements taken up to 40 C with the xenon-flied cell were consistent with the measurements made

with the older, high-Q oscillator. However, within 0.3 K of Tc the observed transfer function deviated from the

_I*_*_B_*_DI_*_*_oD_4_*_o*_i*_**I_s_o_*D_t_o_*_*_O_*_j_*D_o_I_I_o_o_*_*_I_o_*_j_**_*_*_t_t_*_)6_**_**_D_i_*_*_B_*_j_I*_i_*_

I1-7 4
II. MSADProgramTasks-- Flight Research Discipline: Fluid Physics

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expected response by as much as 3%. The behavior was consistent with a "sloshing" mode of the straufied of the

sample, an effect which will not be present in low gravity.

Improvements of the cell:

We implemented several improvements to the construction of the t-trstflight cell, delivered in September 1994. The

metal gaskets were made more secure by increasing the torque on the gasket's bolts to 17 inch-pounds, by using

stronger bolts with a thread lubricant, and by retightening the bolts tollowing the thermal cycles due to vacuum

bakeout and sample loading. The mechanical stress on the electrical feedthrus was reduced by use of a pliable jig to

increase the precision of electrode attachment and by casting epoxy around the external pins. The stainless steel fill

line was replaced by a copper fill line which could be crimped reliably.

Motivated by the observation of undesired sloshing modes between 0.5 and 2.5 Hz, we added an anti-sloshing baffle

to the cell. Although these modes will not exist in low gravity, they complicate the analysis of the l-g data. The

new baffle eliminated modes above 1.1 Hz, and it reduced the amplitude of the lower-frequency modes by a factor of

more than two. Its design was guided by measurements on water troughs of variable geometry as well as by

extensive tests in xenon cells with and without a baffle.

Supplemental technical support:

We collaborated with Nile Oldham of NIST's Electricity Division to develop a prototype single-board,

programmable, voltage divider which met CVX's requirements for precision and stability in balancing the

capacitance bridge. Although the th'st concept of a multiplying DAC circuit exhibited an unacceptable temperature

coetllcient in prototype, the second concept of a 9-bit ratio transformer was successful. The prototype's transfer

function matched that of the large commercial ratio transformer presently used in the laboratory, and it contributed

negligibly to the noise of the viscosity measurement.

To clarity the design of the viscometry electronics, we obtained assistance from J. Cies of Hewlett-Packard in the

torT of a technical report.

Miscellaneous:

The magnitudes of the drive and detection voltages were refined to reduce nonlinear behavior of the oscillator's

transfer function to 0.3%. The expected effect of a possible divergence of the dielectric constant near the critical

point was shown by calculation to be negligible. The effect of residual gas during the oscillator's vacuum

characterization was shown to be negligible.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/94 EXPIRATION: 1/97

PROJECT IDENTIFICATION: 963-03-0A-19

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Berg, F.F. and Gruner, K. Remarkably small critical exponent for the viscosity of a polymer solution. J. Chem. Phys..

vol. 101, 1513 (1994).

Presentations

Berg, R.F. "Hydrodynamic similarity in an oscillating body viscometer." 121h Symposium on Thermophysical

Properties, Boulder. CO. June 19-24, 1994.

11--7 $
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

t llll ill I llll III III i I I ill I lilll I llilll I olin i I oil Ollll illilll I lOIIlllllllillllllll Ill ill Ill III Ill Ill I OIlllllllllln i I lllllll lllli lltl I llllllll Ill Illlll I ill l lllll II I Ill I oiinllil lllll llu Jill oi ill ill oi ooooooi on ln i i liillllloll oillllililill i i n i

The Dynamics of Disorder-Order Transitions in Hard Sphere Colloidal Dispersions

PRINCIPALINVESTIGATOR:Prof. Paul M. ChaJkin Princeton University

CO-INVESTIGATORS:

Prof. W.B. Russell Princeton University

TASK OBJECTIVE:

To study the disorder-order transition in a hard sphere colloidal particle system, utilizing laser light scattering to

detect (1) viscosity changes as the transition from fluid to crystal to glass occurs, (2) diffusion of particles, (3)

nucleation and growth of the crystals and (4) rigidity "alter the transition to a glass is complete.

TASK DESCRIPTION:

The approach has focused on simulating low-gravity by tluidizing a bed of specially prepared hard spheres (silica

particles with coatings of short-chain polymers) with a counterflow of solvent. This counterflow allows an

approximation of microgravity.

TASK SiGNiFiCANCE:

Materi',ds Research - the study of crystal formation in the microgravity environment can lead to a greater

understanding of how gravity affects the Ibrmation of many kinds of materials. The focus of this experiment is to

use a material which can exist in multiple phases depending on its concentration in a colloidal suspension. Laser

light scattering images will provide structural information about the material as it goes through liquid, ordered

crystal, and disordered glass phases.

PROG_IESSDUFtIN6 FY 1994:

Light scattering has been used in the lab to verify material structure in 1-g. Sample preparation techniques are

being refined which include procedures lot index matching the sample and the sample container. Various volume

fractions of solvent mixture have been tested to assess which combinations will be used for flight. The main focus

in 1995 will be the detemunation and minimization of particle polydispersity of the samples.

A preliminary Science Requirement Document (SRD) was prepared and Science Concept Review (SCR) was held in

January, 1994. The investigators presented the science status and plans for the flight experiment to an independent

peer review panel. The review panel reccomended approval of SCR based on outstanding scientific merit of the

proposed experiment. NASA HQ approved the SCR.

The SRD was updated to its near-final form based on results of the ground-based testing and recommendations of the

SCR peer review panel. Requirements Definition Review was held in September, 1994. The investigators made

the science presentation. The RDR was also successful and the experiment has now been selected for flight.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 4/90 EXPIRATION: 7/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-24-0A-29

MS Students: 2 MS Degrees: 0 NASA CONTRACT NO.:NAG3-1158

PhD Students: 0 PhD Degrees: 1 RESPONSIBLECENTER: LeRC

_iioiiIiiIiiiiiIi_iIi_Iuji_iiii_oiiiiiijna_uni_liIiuiIiIIiiiiniIiiI_iIiiii_Iiioiijii_iiiI1inuiniiiniiiiiiiiiiiniiiiiiuiiiiiiIiiiIi_iiiIiI_iI_IiiI_oIi_iiIio_IIIuiii_i_IiiIiiIiiiiiIIiIIiI_iIiiiiiIiiIiiIiiiiiiii_i_iIuinin_nuI

11.-7 6
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

,Journals

Russel, W.B., and Sperry. P.R. Effect of microstructures on the viscosity of hard sphere colloids and modulus of

composites. Progress in Organic Coatings. vol. 23, 305 f1994).

Rutgers. M.A.. Dunsmuir, J., Russet, W.B., and Chaikin, P.M. Crystalline fluidized beds. Physical Review E, (to appear).

Rutgers, M.A.. Dunsmuir. J., Russel. WB., and Chaikin, P.M. Hard sphere equation of state. Science. (submitted).

11-7 7
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

allaoolool|lluoltooll*, i|l|al.llonaoesll "li_i_"_|oI_1i_iI_ii_oi_II_"i_j_iH"_a"n"_"_"H_|lu_o_I_"_I1oH .I.V._.l.ll.nHaOgl0gl.llHl_|lHllnl011g. o_l.lgOllollolHIIolllnulnllilHIonlollg

Kinetics of Diffusional Droplet Growth

PRINCIPAL INVESTIGATOR: Dr. Donald O. Frazier NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

M. Glicksman

J. Rogers

J. Downey

Rensselaer Polytechnic Institute

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

To determine droplet growth rate constants and changes in size distributions using optical techniques for recording

droplet data with time.

TASK DESCRIPTION:

A transparent model binary liquid/liquid miscibility-gap type solution was the system of choice. The experunental

approach was to deploy a fixed array of droplets of one liquid phase into a cell filled with the conjugate phase. This

approach was to greatly reduce any residual gravity effects and eliminate the possibility of coalescence.

Ground-based studies were to determine the experimental parameters required to maximize the amount of data on

"'pure" Ostwald ripening obtainable during the flight experiment. For tethered droplets, it was considered important

to determine such parameters as volume traction of droplet phase, initial droplet number, droplet spacing and sizes,

the time required for the experiment, and ideal concentrations tbr supersaturation and growth.

TASK SIGNIFICANCE:

To a large extent, particle growth and distribution determine the mechanical properties of an 'alloy. Capabilities

provided by holographic techniques enabling observations of diffusional growth of a second phase in a model.

transparent two-phase system, allow detailed analyses of particle size and number distribution. Direct observation

of these phenomena allow experimental determination of the scaling laws which define the tune evolution of

discrete phase droplets m the asymptotic limit. To our knowledge, this technique is unique for providing real-time

optical observation of these processes.

PROGRESSDURING FY 1994:

Our work has resulted in determination of the best methods for performing ground-based testing. Ground work

requires a transparent isopycnic system. Sensitivity to gravitational fields should be tested, in the laboratory, by

tethering two droplets in a test cell and comparing growth kinetics at varying temperatures. Convective flows

increase with increasing conjugate phase density differences which are relatively strong functions of temperature.

Quench experiments in narrow path-length cells should allow observation of coarsening, possibly on the cell walls,

in an ensemble of droplets. Narrow path-length is a prerequisite for establishing transparency quickly in high

droplet density media.

These experiments began while submitting a new proposal to continue ground-based testing. Postponment of flight

preparation is a consequence of the inadequacy of hardware suggested for flight. The Bubble Drop and Particle Unit

was not appropriate because of its inefficiencies regarding thermal fluctuations. Unless approximately one

millikelvin thermal control is available, spurious nucleation and droplet dissolution will disrupt distribution

self-similarity, critical to late-stage coarsening theory.

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11-7 8
II. MSADProgramTasks-- Flight Research Discipline: Fluid Physics

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/89 EXPIRATION: 12/93

PROJECT IDENTIFICATION: 963-24-08-01

NASA CONTRACT NO.: In-hou_

RESPONSIBLECENTER: MSFC

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II-7 9
MicroscaleHydrodynamics Near Moving Contact Lines

PRINCIPALINVESTIGATOR: Prof. Stephen Garoff Carnegie Mellon University

CO-INVESTIGATORS:

M. Weislogel NASA Lewis Research Center (LeRC)

TASK OBJECTIVE;

The objective of this study is to characterize the relationship between macroscopically observed dynamic contact

angles and the microscopic fluid physics occurring near the contact line.

TASK DESCRIPTION;

This task consists primarily of low-gravity experimental studies on moving contact lines. The experiments will

simultaneously measure flow fields and the fluid/fluid interlace very near the moving contact line using video

microscopy and particle image velocimetry. The experiments will be conducted in low gravit)/since it is in low

gravity that interracial phenomena dictate the fluid/fluid interlace shape and location.

TASK SIGNIFICANCE:

The essential points of the investigation are:

I. Are the viscous stresses near a moving contact line appropriately described by present phenomenological

models?

2. Can predictive models for spreading be developed tot complex systems (rough surfaces, non-Newtonian fluids,

etc.) if the flow fields and interlace shapes near a contact line are known?

3. What is the nature of the unique fluid dynamical processes near a moving contact line? How do these processes

depend on the properties of the fluids and the solid surface involved? How do these processes determine the true

dynamic contact angle?

PROGRESSDURING FY 1994:

Our efforts this year focused on two areas: (1) working with the engineering team to refine science requirements for

the flight expertment, consult on hardware design, prepare the Science Requirement Document, and present the

Science Concept Review and (2) ground-based research on the moving contact line problem.

Definition of science requirements and discussions on hardware design for the abbreviated Cfasttrack") flight

experiment were a major fraction of the total effort during the past contract year. Cell dimensions were set by

calculations of static interface shapes, critical bond numbers, and recirculation flows. The requirement on thermal

gradients in the experiment was chosen through a comparison of residual Marangoni flow and the driven flow under

investigation. New UV cleaning chambers were built and tests were run on the effectiveness and resiliency of the

UV cleaning process. In several meetings and correspondence, details of the cleaning techniques were transmitted

from the science team at CMU to the engineering team at NASA Lewis Research Center. The science objectives of

the flight experiment were refined and a minimal flight test matrix was established. Requirements were established

tor optical design, materials selection and characterization, data acquisition, temperature and pressure control, as well

as acceleration levels and measurement. All requirements were recorded in drafts of the Science Requirement

Document. The Science Concept Review occurred on May 4, 1994. This review presented the scientific

motivation and experimental plans only for the "fasttrack" flight experiment.

Our ground-based research on moving contact lines produced important results both on the hydrodynamics in the

intermediate region and on the inner scale physics:

II.-80
II. MSADProgramTasks -- Flight Research Discipline: Fluid Physics

_I_|m!*!Ig**_i_*_!!_*i_|i_*Il*!**_*_!!|*_**l_*!_!Is_!_|_*_*|_i!*lI*_IIiiI_l!|li*¢|*li_l*I_*|W|_||_|l_||_l*_il_s_|l_*l_*!_*lIll_l|ll¢!!*_|_*|_|*l*|**H_*_ll*l_|ill_¢!Qi!ll|_lll_Ill_ll*|!llllH*_lIsl_¢I_ll|l*I!lIllIl_Ill_l

We have measured the dynamic interface shape over long distances f'2rnm). We found that the parameter w0

determined by fitting the dynamic data near the contact line to the composite model is the contact angle for the

interface shape Jar from the contact line fit to a static inter/ace shape. This result confu'rns a fundamental

hypothesis of the model of the microscale hydrodynamics near a moving contact line. However, within the accuracy

of our experiments, the interface shape at Ca's as low as 0.01 is measurably different from the static shape even at

distances of 1.2mm from the contact line. This result raises questions about the accuracy of measurements of

dynamic interfaces made by other techniques and reported in the literature.

By measuring the inter/ace shape at increasing Ca, we have determined the limits of the presently available models

for the hydrodynamics near moving contact lines. We have made the titst measurements of dynamic interface shapes

in depression. We find that the present models are adequate for Ca<0.1. Above this Ca, the model predicts too

large a curvature at snmll distances flom the contact line. The region where the model is inadequate expands as CA

increases. The breakdown is either due to an insufficient number of terms in the Ca expansion describing the

intermediate region or to the inner scale hydrodynamics affecting the inter/ace shape at unexpectedly large distances.

The model of the intermediate region can be extended to higher Ca. It then provides an additional parameter

describing the inner scale physics. However, our measurements show that this expansion cannot be used in

terrestrial measurements because of contamination ti'om geometry, dependent terms which cannot be expressed

analytically. This result proves that microgravity measurements, which increase the outer length scale, will provide

a unique opportunity to measure an additional parameter with which to characterize inner scale physics.

Our materials studies show that the inner scale hydrodynamics of polymer melts is sensitive to local

polymer/surface interactions. In a low Ca regime, the spreading of polydimethylsiloxanes (PDMS) across a 7740

Pyrex surface is strongly affected by the end termination chemistry of the polymer:, hydroxyl ternunated PDMS

exhibiting a strong velocity dependence and methyl terminated PDMS exhibiting a weak dependence. Further, the

hydroxyl terminated spreading varies with polymer viscosity in this regime. At higher Ca, the behavior of PDMS

with either termination is similar. We are presently investigating scaling relations in this high Ca regime. We

have "also lound that the spreading behavior of the hydroxyl terminated PDMS is strongly dependent on the level of

absorbed water on the Pyrex surface.

Initial measurements of the velocity field near the moving contact line have been made. The PDMS is seeded with

particles of AI2(OH)_ coated with oleic acid.

The particles are in 1-10_rn in diameter. Particle trajectories and velocity fields are measured and compared to the

fields which are predicted by the modulated wedge approximation central to the model of the intermediate region

which we use to fit the interface shape. At low Ca, the model correctly predicts the flow field down to distances on

the order of 50_rn from the contact line. These studies will continue probing closer to the contact line and higher

Ca flows.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 12/95

BS Students: 0 PROJECT IDENTIFICATION: 963-25-OA-81

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 3

BIBLIOGRAPHIC CITATIONSFOR FY t994:

Journals

Willson, K.R. and Garoff, S. Effect of chain termination chemistry and molecular weight on dynamic wetting of polymer

liquids, to be published in Colloids and Polymers. (August 1994).

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I1-8 ]
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

Proceedings

Garoff. S.. Chen. Q., Rame. E., and Willson, K.R. "Microscale hydrodynamics near moving contact lines." Proceedings

of the 2nd NASA Microgravity Fluids Conference, Cleveland, OH. June. 1994.

Presentations

Chen, Q., and Garoff, S. "Dynamic contact angles and interface shapes at high capillary number." American Physical

Society Meeting, Pittsburgh, PA, March, 1994.

Chen, Q., Rame, E., and Garoff, S. "Measuring dynamic contact angles: an experimental study of the breakdown of present

theory." AIChE Annual Meeting, San Francisco. CA, November 1994.

Garoff. S., Chen, Q., Rame, E., and Willson, K.R. "Microscale hydrodynamics near moving contact lines." Second NASA

Microgravity Fluids Conference, Cleveland, OH, June 1994.

Rame, E. "The boundary condition at a moving contact line: an experimental study of the interpretation of the dynamic

contact angle." American Physical Society/Division of Fluid Dynamics, Atlanta, GA, November 1994.

Willson, K.R., and Garoff, S. "Dominant factors controlling dynamic wetting of PDMS fluids." American Physical

Society Meeting, Pittsburgh, PA, March, 1994.

Willson. K.R. and Garoff, S. "Dominant factors controlling dynamic wetting of PDMS fluids." 68th ACS Colloid and

Surface Science Symposium, Stanford. CA. June 1994.

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I1-82
II. MSAD Program Tasks h Flight Research Discipline: Fluid Physics

III I III III I I I Ill I Ill I IIIIII I I lllll III I III I IIII Ill I I I I q Oil I III I I, I I I I I I I I II III I II I II I ,I IIII III I I III I II l II I I IIIIIII Ill III I l$11 I I I III I I II III I I lllll I III IIIIIIIIII IIII _____________n___________________________________________________________________

Plasma Dust Crystallization

PRINCIPALINVESTIGATOR:Prof. John A. Goree University of Iowa

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to demonstrate that charged particulates in a plasma environment form an ordered

structure.

TASK DESCRIPTION:

The investigator will design and test apparatus for radio-lYequency (RF) plasma generation / particulate

confinement, and analyze the structure of suspended particulates. This will include working with German scientists

in designing microgravity experiments.

TASK SIGNIFICANCE:

This investigation begins a new genre of microgravity research. It will provide: (1) a macroscopic model of how

atoms arrange themselves in a crystal or liquid, (2) a much-needed test of dusty plasma theories used in space

physics and astronomy, and (3) an understanding of particulate contamination during plasma processing steps of

microchip manufacturing.

PROGRESSDURINGFY 1994:

This project represents an entirely new area of scientific research. When micron-size particulates are inserted into a

plasma, they become charged and can arrange themselves in an ordered structure, ranging from a liquid to a

crystalline lattice. This structure is suspended in the vacuum, and it is visible to the unaided eye. This is of interest

for basic science, since it serves as a model system for studying crystalline structures and phase transitions to more

disordered states. It is "also of interest tot industry, since we use apparatus identical to the tools used to etch silicon

waters in semiconductor manufacturing; particulates are of great tmportance because they can contaminate the

silicon wat'er. Gravity is a significant force acting on these particulates.

Experimental progr¢,_:

1. We have submitted and published in Physical Review Letters a paper describing for the first time an observation

of a crystalline lattice of charged grains suspended in a plasma. This paper has generated considerable interest, and

news arucles about it have been written in Nature, Physics World, and Science News.

2. A new laboratory test stand has been assembled, and we have now used it to prepare more extensive data. We

now have images of our particulate cloud made by video cameras pointing at sheets of laser light that cut through

the cloud in vertical and horizontal cross sections. These experiments are yielding very clear images of ordered

states ranging from liquid to hexatic regimes. We have analyzed these data using pair and bond-angle correlation

methods developed originally by experimenters in colloidal suspensions. These experiments serve the dual role of

providing exciting experimental results in their own right, helping to define this new area of research, while also

serving as an early model for developing flight hardware. It is increasingly clear from the data that gravity crushes

our particulate cloud into an essentially 2-D ordered structure, and that microgravity conditions will be required to

achieve a fully 3-D ordered state.

3. In cooperation with our DARA-funded German collaborators, we are now discussing apparatus configurations for

11--83
a future Get Away Special flight experiment. In this international scientific collaboration, the PI is the senior

experimenter.

Theory_ progress:

We have begun a second theoretical effort, having "already completed a first during FY93. We will model the

dynamics of the particulates in our plasma. This effort will continue over the next year. with a visiting scientist

from Norway doing much of the work. It will help in understanding our experiments and in quantifying the role of

gravity in them.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 2

PhD Students: 0

TASK INITIATION: 4/93 EXPIRATION: 4/96

PROJECT IDENTIFICATION: 963-24-08-02

NASA CONTRACT NO.: NAG8-292

RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Cui, C., and Goree. J. Fluctuations _f the charge on a dust erain in a plasma. IEEE Transactions on Plasma Science, vol.

22. 151-158 (1994).

Goree, J. Charging of particulates in a plasma. Plasma Sources Science and Technology, vol. 3. 400-406 (1994),

Goree, J., and Chiu, Y.T. Dust contamination of the spacecraft environment by exposure to plasma. J. of Spacecraft and

Rockets. vol. 30, 765-767 (1993).

Thomas, H., Morrill. G.. Demmel. V.. Goree, L, Feuerbacher, B., and MOhlmann. D. Plasma crystal: coulomb

crystallization in a dusty plasma. Physical Review Letters, vol. 72, 652-656 1994).

Presentations

Goree. J. "Plasma crystals." AIAA 32nd Aerospace Sciences Meeting. Symposmm on Microgravity Science, Reno. NV,

Janaury 10-13, 1994.

G,,_ree. J. "Plasma crystals." NASA Microgravity Fluid Physics Conference. Cleveland. OH, June 12-13, 1994.

Goree. J. "Dusty plasma exoeriments and theory." UCSD Plasma Physics Seminar, June. 1994.

Goree, J. "Dusty plasma experiments and theory." Invited talk at the Workshop on Non-Neutral Plasma, July, 1994.

Praburam, G., and Goree, J. "Observations of particle layers levitated in an rf sputtering plasma." Gaseous Electronics

Conference, Montreal. Canada, October. 1993.

Praburma, G.. and Goree, J. "Observations of particle layers levitated in an rf sputtering plasma." American Physical

Society Meeting, Division of Plasma Physics, November. 1993.

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11-84
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

Evaporation from a Meniscus within a Capiliary Tube in Microgravity

PRINCIPALINVESTIGATOR:Prof. Kevin P. Hallinan University of Dayton

CO-INVESTIGATORS:

Dr. J. Ervin University of Dayton

TASK OBJECTIVE:

The primary objective of this project is to investigate the thermocapillary Effect on the intert'acial instability of an

evaporating extended meniscus and to corroborate the disjoining pressure gradient theory for describing the thin t-tim

fluid flow.

TASK DESCRIPTION:

In order to effectively study the thin film region of a capillary interface, experiments will be conducted in a large

evaporation/condensation loop in a low-gravity environment. The experiments will include simultaneous particle

image velocimetry (PIV), interferometry, and wall temperature measurement in order to obtam the fluid velocities,

the interface shape, and the w_dl temperature in the thin tilm region. Thennocapillary effecLs will be quantified by

the measured wall temperature and the fluid velocity profile in the dnn fihn region.

TASK SIGNIFICANCE:

1. The study of the thermocapillary effect on the interracial instability of an evaporating extended meniscus may

help explain the failure of Capilla-Dj Pump Loops in a microgravity environment. The knowledge obtained from

this study could result in radical new heat exchanger technologies that will benefit both space exploration and

terrestrial applications.

2. This study can help strengthen support for the use of disjoining pressure gradient theory, to describe fluid flow in

thin fihns. Such an understanding can complete the theory of thin-film physics which is relewmt to many

important technologies from the thin-film coating to materials processings.

PROGRESSDURINGFY 1994:

In FY94, numerical simulation of the thermo-fluid physics m the near contact line region was conducted to better

understand the competing effects of thermocapillary, stresses which oppose the liquid motion into this region and the

disjoining pressure gradient which acts as the driver for the flow in this region. It was shown that a temperature

difference of as little Ks 0.001K between the w',dl and the vapor could signiflcandy affect the thin film flow field and

marginally affect the total thin film heat transport and shape. The macroscopic influences of the thermocapillary

stresses at near contact line were also observed experimentally by applying heat input to an evaporating liquid in a

small-diameter, vertical capillary tubes. As the heat input to the meniscus was increased, the meniscus receded from

the static equilibrium position which, by scaling arguments, is attributable m near contact line thermocapillary

stresses. In addition, progress has been made in the continuing development of the Coherent Forward Scattering

Particle Velocimetry technique which ultimately will be used to measure die velocity field in the evaporating thin

liquid film near the contact line. An analytical analysis has identified the lengthscales near the contact line where

the therm(x:apillary stresses can be most severe. Knowledge of the salient lengthsca.les has provided the gui "dance for

selecting the optics and light source to be employed to extract information near the contact line. Polystyrene

spherical seeding particles, 0.1 microns in diameter, will be the fluid tracers used to measure the near contact line

velocity field. A Nikon Labophot microscope with Koehnler illumination and having a 60X, 0.85 N.A.

microscopic objective lens has been proven capable of providing reasonable diffraction Images of particles in and out

of locus reside of an evaporating liquid film.
STUDENTS FUNDED UNDER RESEARCH:

BS Students: 3

MS Students: O

PhD Students: 3

TASK INITIATION: 12/92 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 963-25-0A-21

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Hallinan. K.P., Chebaro, H.C., Kim, S.J. and Chang, W.S. Evaporation from a capillarity-resupplied extend meniscus

within a cylindrical pore for non-isothermal interracial conditions, accepted for publication to J. of Thermophysics and

Heat Transfer, (1994).

Presentations

He, Q. and Hallinan, K.P. "Thermocapillary effects on the evaporating extended meniscus." accepted for presentation at

the ASME-WAM, Chicago. IL. November 5-8. 1994.

Pratt. D.M. and Hallinan. K.P. "An investigation of thermocapillary effects on a heated capillary re-supplied meniscus for

low bond numbers." accepted for presentation at the 3rd Latin American Symposium on Fluid Mechanics. Caracas.

Venezuala, February 5-8. 1994.

11--8 6
If. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

"_to_to_oo_"uIn1"_o_nolaooaoo_o|agoIno_aon_|olain_oo_oioo"_"_"'"a"_"l"_onla"a"_oo_oaaonaonami"t"IoiI"Ioo_ao_"_nolaiiaIIIooolIoIa"aooia"_I_Iaoiaoo_" i ollaolaoolloon .la|na.noonooln|lao|ao|loolaooaloaoolol_nlla.aoaulolaollln

Geophysical Fluid Flow Ceil

PRINCIPALINVESTIGATOR:Dr. John E. Hart University of Colorado, Boulder

CO-iNVESTIGATORS:

F. Leslie

T. Miller

J. Toomre

D. Ohlsen

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

University of Colorado, Boulder

University of Colorado, Boulder

TASK OBJECTIVE:

The Geophysical Fluid Flow Cell experiment (GFFC) takes advantage of the unique environment of the

microgravity laboratory, which permits threes that would otherwise be swamped by normal terrestrial gravity to

become dominant. The GFFC uses electrostatic forces to warp gravity into a radial vector field, centrally directed

towards the center of the cell. This allows us to perform visualiztions of thermal convection in a spherical shell of

liquid subject to imposed differential heating and basic rotation, where the active buoyancy forces are radially

directed, as in planetary, atmospheres and stars. The objective of the expertments is to categorize the types of

convective patterns that can occur in highly nonlinear and turbulent flows with varying amounts of basic rotation

and thermal stress.

TASK DESCRIPTION:

1. A significant modification to the original GFFC experiment that flew previously on Spacelab-III is the addition

of real-time video visualizations of the fluid turbulence that can be downlinked from the shuttle to scientists on the

ground. This permits interactive experiments that can identify and focus on important flow regimes. Design,

construction and verification of space qualified hardware to effect this video downlink is a major hardware task.

2. In preparation for flight, theoretical, computational, and terrestrial laboratory stmulations of rotating convection

are required in order to suggest particular experiments that can critically advance our basic understanding of such

phenomena, as well as make contributions to the science of geophysical and astrophysical fluid dynamics.

Theoretical and computational models typically involve assumptions that will be checked in the spacelab flights,

and terrestrial experiments are planar in geometry., ",allowing comparison of fundamental differences between "fiat"

and "spherical" convection.

TASK SIGNIFICANCE:

The spherical configuration and radial gravity of the Geophysical Fluid Flow Cell is significant because large-scale

motions of the atmospheres of planets and stars are constrained by the inherent spherical geometry of these bodies.

Furthermore the flows on them are constrained by rotation, under the action of same Coriolis forces that shape

Earth's weather, and by buoyancy forces which result in hot fluid rising in a radial direction. It is impossible to

study such motions in the terrestrial laboratory because gravity is uniformly directed. The GFFC experiments will

provide basic laboratory data that can be applied to problems of cloud patterns on the giant planets, differential

rotation on the Sun, and motions in Earth's core, mantle and atmosphere.

PROGRESSDURING FY 1994:

1. The GFFC Video Acquisition Module (VAM) and associated documentation were completed and shipped to

MSFC for integration with the GFFC. Tests there indicate the VAM is functioning properly.

2. The computational code of Gary. Glatzmaler, previously used with the SL3 GFFC results, was upgraded. Now

more resolution can be used, and it will be possible to computationally simulate most of the anticipated GFFC

USML-2 runs. Research Associate Dr. Dan Ohlsen will begin running cases to be studied on USML-2 in early

FY95.

11-87
3. A major laboratory experiment on turbulent rotating convection was constructed. 11permits in situ thermal

measurements and remote measurment of velocity fields of rotating convection using particle image velocimetry

(PIV). Initial results show strong cyclonic vortices (tornado turbulence) which are associated with a strong unstalbe

mterior stratification (compare with non-rotating convection where the interior stratilicatJon in neutral).

4. Experiments and computational simulation of b-convection (rotating convection constrained to lie near the

equator where gravity is perpendicular to rota0on) were completed. The computational simulations show strong jets

(like Jupiter), but the experiment, which run at higher Prandtl number, do not. We intend to look more closely at

this problem in FY95.

STUDENTSFUNDED UNDER RESEARCH: TASKINITIATION: 12/88 EXPIRATION: 3/94

PROJECTIDENTIFICATION:963-24-08-04

NASA CONTRACTNO,NAS6-3!958

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Hart, J.E.. Albaiz. A., and Leben. R. Fl_w separation and chaos in a rotating annulus. Computational Fluid Dynamics.

vol. 2, 59-72 (1993).

Hart, J.E.. and BrummeU, N. High Rayleigh number b-convection. Geophys. and Astrophys. Fluid Dyn., vol. 68. 85-114

(1993).

|!_N!|__|_!__t_|_!||__H_!___||__||__n||!|_!|____!_!!!!!_!__t!_______!__||||__||!!_|!|__|_!|_!_!!*___|_____*__!__!____|_!|!_H_____||_!|!!__!_!||__e|_e_______!______|__|_____!|_|_!!__!_|_|!_|__||!|!_|!_|___|__|__|_e|!|!|e__|__|_!__!!|_!_|!!|!

1I-.88
Interracial Phenomena in Multilayered Fluid Systems

PRINCIPALINVESTIGATOR:Prof. Jean N. Koster University of Colorado, Boulder

CO-INVESTIGATORS:

Prof. S. Biringen University of Colorado, Boulder

TASK OBJECTIVE:

The main objective of the research is to design a three-liquid-layer flight experiment that will study the interaction

of two interfacial tension forces of different mabmitude, and their effects on thermocapillary, fluid flow induced in

adjacent liquid layers. The thermocapillary flow results from temperature gradients parallel to the fluid interfaces.

In addition, the mechanical coupling between the immiscible layers and the suppression of convective flow will be

investigated. The conditions for the existence for oscillatory flow, and the effects of g-jitter may ',also be studied.

TASK DESCRIPTION:

The generaJ approach is to conduct ground-based norm'd-gravity testing and develop theoretic',d models of the

combined buoyant and thermocapillary convection phenomena. The instrumentation and diagnostics are centered

around the physics of interest; namely, flow field.s, temperature fields, and intertacial shapes. The theories and

numerical models developed and verified with the 1-g data was used to predict the results of the flight experiment on

the IML-2 mission.

TASK SIGNIFICANCE:

The results are expected to significandy advance our knowledge in the area of surface-tension-driven convection in

multilayered fluid systems. The scientific results will find applications related to encapsulated float zone

processing. Float zone processes are a technique in which space processing of crystals can be done while

minimizing imperfections.

PROGRESSDURING FY1994:

There were many activities on the flight project side. Activities were concentrated on preparing for and in support

of the flight experiment in July 1994. These activities included participating in ground testing of the

engineering/flight models in Europe; tamiliarizing the crew with science background of the experiment; and

attending various mission simulations at MSFC. During the course of the year, the PI expressed concerns about

maintaining liquid-liquid interl'aces during curtain retraction, having sufficiently small particles m the liquids to

achieve the required velocity field resolution, and having equal pressures in each of the three fluid layers so that the

interlaces remained fiat. During the actuai mission in July, flat interfaces were, unfortunately, lost when the first

curtain withdrawai was nearly halt completed. The finai fluid configuration (when both curtains were retracted) was

the undesirable shape of a fluorinert ball surrounded by silicone oil. Although some tests were subsequently done

with this configuration, it is felt that little scientific data resulted from the experiment.

Ground-based research continued in the PI's labs in Boulder during the year. Research was conducted in the

following areas: natural convection in multilayer systems; combined thermocapillary and natural convection in

multilayer systems; Rayleigh Benard convection in multilayer systems; and assessing the effect of g-jitter on fluid

interlaces. The work for the next year is currently being replanned in light of the flight experiment resmts. One of

the priorities of the work to be done will be to better understand how to establish such interfaces in microgravity.

!1-89
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1|/89 EXPIRATION: 12/95

BS Students: 0 PROJECT IDENTIFICATION: 963-24-00-05

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 4

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Burkersroda, C.V., Prakash. A. and Koster, J.N. Interracial tension between fluorinert.s and silicone oils. accepted by

Microgravity Quarterly, (1994).

Prakash, A. and Koster, J.N. Penetrative Convection in sublayer of water including density inversion. Warme-und

Stoffubertragung, 29, 37-49 (1993).

Prakash, A. and Koster, J.N. Convection in multiple layers of immiscible liquids in a shallow cavity - Part II: steady

thermocapillary convection. International Journal of Multiphase Flow. 20. 397-414 (1994).

Prakash, A. and Koster, J.N. Thermocapillary convection in three immiscible liquid layers, accepted by Microgravity

Quarterly, (1994).

Prakash, A. and Koster, N.N. Natural and thermocapillary convection in three layers. European Journal of Mechanics

B/Fluids, 12, 635-655 (1993).

Schmitt, T., Koster, J.N., and Hamacher. H. Particle design for displacement tracking velocimetry, accepted by

Measurement Science and Technology, (1994).

Journal Tong, W. and Koster. J.N. Penetrative convection in sublayer of water including density inversion. Warme-und

Stoffubertragung, 29, 37-49 (1993).

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I1-9 0
Extensional Rheology qf Non-Newtonian Materials

PRINCIPALINVESTIGATOR:Prof. Gareth H. McKinley HarvardUniversity

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this work is to determine the extensional viscosity in uniaxial stretching flow of fluid systems

such as dilute polymer solutions, emulsions, and suspensions. Also, to generate a simple homogeneous shear tree

flow in the material, and to measure the stress response of the material from an imposed rate of deformation

(constant detormaUon rate experiments).

TASK DESCRIPTION:

This effort will require an initial ground-based experLmental design, and ultimate payload implementation, of a

novel experimental apparatus to measure accurately the rheological response of non-Newtonian fluids under

shear-tree conditions that are characteristic of those experienced in the containerless processing of materials.

The proposed instrument generates a homogeneous uniaxial elongation through an exponential stretching of the test

sample, and the spatial uniformity of the detormation rate experienced by the fluid is verified by digital particle

image velocimetry. Direct measurements of the tensile torce exerted by the material then allow calculation of the

extensional viscosity of the fluid.

The design of the apparatus utilizes several of the existing or planned fluid diagnostic modules being considered by

NASA, and in addition, provides a completely new fluid-science flight capability, which can be used repeatedly to

support multi-user rheological measurements tor a wide range of non-Newtonmn fluids.

TASK SIGNIFICANCE:

The extensional viscosity is a fun 'damental physical property of 'all non-Newtonian materials, and cannot be

determined from simple viscometric shear flow experiments. Constitutive equations for viscoelastic fluids such as

dilute polymer solutions predict large changes in the extensional viscosity as the elongation rate is increased;

however, the validity of these theories cannot be confirmed due to the lack of experimental data obtained in

extensional flows. To date, quantitative rheological measurements in shear-tree flows have only been possible tot

highly elastic or "stiff" materials such as polymer melts which can easily be elongated without sagging under a

gravitational body force. By performing similar experiments in an extended microgravity environment it will be

possible for the first time to obtain accurate measurements of the extensional viscosity for more 'mobile' fluids

such as polymer solutions, suspensions and liquid crystalline materials. This rheological data will allow designers

of both space- and ground-based material processes to use improved constitutive models in numerical simulations of

complex two- and three-dimensional fluid flows.

In a simple stretching flow, fluids such as water or syrup exhibit a resistance to stretching that is exactly three

times the value of their Newtonian viscosity. This resistance is usually termed the "extensional viscosity of the

material." However, for fluids containing long macromolecules (e.g., synthetic polymers, liquid crystals, or DNA)

is predicted that the extensional viscosity can be anywhere from 100 to 10000 times greater than the viscosity of

the fluid. In the near future, NASA plans to develop "containerless processing" operations under microgravity and a

detailed understanding of extensional properties in fluids will be absolutely critical -- since, in the "absence of

container walls, the only way to mix, pour, and shape fluids will be through pure stretching motions. Knowledge

of such nonlinear material functions is fundamental to the development and verification of relatively cheap

ground-based computational modeling techniques which can be used effectively in the "a priori" design of advanced

I1-9 1
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

microgravity material processes thereby alleviating the need for costly in-flight pilot experiments. Finally, in

addition to their significance in many industrial processes such as fiber-spinning and film coating operations,

stretching flows of non-Newtonian fluids are of fundamental scientific importance to a number of complex fluid

dynamics phenomena, including the stability and breakup of jets, enhanced oil recovery, and turbulent drag reduction

lot advanced aircralL boaks, and submannes.

PROGRESSDURINGFY 1994:

The second draft of the Science Requirements Document has been submitted and the Science Concept Review was

successfully completed on May 6, 1994. A Boger (polymer solution) Fluid Column deployment breadboard and an

expotentially grooved wheel breadboard for the neutral density tank were completed. A dry wheel breadboard has "also

been constructed, and tests are being planned. The particle image velocimetry apparatus has been built and is being

tested at LeRC.

Future plans include further development and construction of the following:

1. The drive mechanism breadboard testing - Inertial motion of neutral density fluid: viscous diffusion of Boger

fluid

2. Birefringence tests

3. Optical testing: DPIV software integration, particle and laser selection and radial measurement

4. Reducing diameter device (RDD) breadboard testing

5. Load cell and microbalance testing (.01 to 30 grams range required)

6. Sridhar Apparatus testing - Fixed plates then RDD with electronic balance

7. Adiabatic heating - Theoretical estimation

8. Fluid choice - theological analysis of varying concentrations of polyiobutylene (monodisperse)

9. Lubrication - Analysis of slip on wheels in plateau tank

10. Surface tension - Determine correlation of dynamic surface tension to extensional rheology experiment.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: I

PhD Students: 1

TASK JNITIATION: 12/92 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 963-25-0A-36

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Gaudet, S., McKinley, G.H.. Stone, H.A. in AIAA, 32nd Aerospace Sciences, Reno NV. p.l, 1994.

Spiegelberg, S.H,, Gaudet, S.. McKinley, G.H. Second Microgravity Fluid Dynamics Conference, Cleveland. OH, 1994.

__i___|_|_!¢|_|||!_¢__!|__e¢|s¢|_____|__|s|__¢s_|_!|s_|_______s_|_¢|__|__|i||_||______________si____¢!!¢____$____¢__¢|______s¢|_____|__|__!!|_w____|________|_i__________|_¢|!|||_|s_||__||!|_||___!_|s____||__|__|_|||_|is_____|____||_|||||_!||s__

I1-92
Pool Boiling Experiment

PRINCIPALINVESTIGATOR:Prof. Herman Merte, Jr. University of Michigan

Co-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The program described here seeks to improve the understanding of the fundarnental mechanisms that constitute

nucleate pool boiling. The vehicle for accomplishing this is an investigation, including experiments to be

conducted in microgravity and coupled with appropriate analyses, of the heat transfer and vapor bubble dynamics

associated with nucleation, bubble growth or collapse, and subsequent motion. Certain effects that can be neglected

at normal Earth gravity, such as surface tension and vapor momentum, can become quite significant in

microgravity. Momentum imparted to the liquid by the vapor bubble during growth tends to draw the vapor bubble

away from the surface, depending on the rate of growth, which in turn is governed by the temperature distribution in

the liquid. Thermophoretic tortes, arising from the variation of the liquid-vapor surface tension with telnperature,

on the other hand, tend to move the vapor bubble toward the region of higher temperature. The bubble motion will

be governed by which of these two effects prevail.

The elements of nucleate boiling, for which research conducted under microgravity would advance the basic

understanding, are:

1. Nucleation or onset of boiling. Indications are that both heater surface temperature and temperature distribution

in the liquid are necessary, to describe nucleation.

2. The dynamic growth of a vapor bubble in the vicinity of the heater surface. This includes the shape as well as

motion of the liquid-vapor interlace as growth is taking place. These are influenced by the liquid temperature

distribution at the initiation of growth.

3. The subsequent behavior of the vapor bubble. This includes the motion, whether departure takes place or not,

and the associated heat wansfer.

TASK DESCRIPTION:

In the proposed experiment, a pool of liquid--initially at a precisely defined pressure and temperature--will be

subjected to a step-imposed heat flux from a semi_ansparent thin-film heater forming part of one wail of the

container, such that boiling is initiated and maintained for a defined period of time at a constant pressure level.

Transient measurements of the heater surface and fluids temperatures near the surface will be made, noting especially

the conditions of the boiling process in two simultaneous views, from beneath the heating surface and from the

side. The conduct of the experiment and the data acquisition will be completely automated and self-contained. For

the initial flight, a total of nine tests are proposed, with three levels of heat flux and three levels of subcooling.

TASK SIGNIFICANCE:

The outcome of the experiment is expected to include the following:

1. Observation of the liquid-vapor behavior, including bubble growth and motion as functions of heat flux, initial

subcooling and time, and correlation with observed heater surface temperature variation.

2. Use of initial liquid temperature distribution at nucleation to compute vapor bubble growth rate for comparison

with observation.

3. Measurement of delay time to nucleation tbr correlation with nucleation theory.

__u_n_nniu_u_u_n__n_n__u_n__n_I_nju_u_*_u_u_

11-9 3
II. MSADProgramTasks-- Flight Research Discipline: Fluid Physics

Anyone who has ever boiled water on a stove is familiar with nucleate pool boiling. Even though it is an everyday

event, scientists do not understand precisely how it works, because Earth's gravity influences how bubbles form and

grow in boiling liquids.

NASA is interested in results from this experiment, because boiling liquids generates bubbles which are very

etlicient at transferring large amounts of heat. Finding new ways to dissipate heat ti-om the space shutt/e or future

manned space platforms will be vital to the success of long term missions.

There are potential benefits closer to home as well, including more effective a_r conditioning and refrigeration

systems and improvements in power plants that could reduce the cost of generating electricity.

PROGRESSDURING FY 1994:

The prototype hardware for the Pool Boiling Expertment was flown aboard the SL-J mission on September 12-20,

1992. Performance of the hardware was "'near perfect." The data clearly reveal that pool boiling in reduced gravity

(10 _g) is a transient process and not a steady periodic one. At the higher-heat flux tests (8 W/cm_'), the

temperature, as well as the vapor content continued to increase. Tests conducted at the lower-heat flux levels

resulted in a rapid spreading of the vapor across the heater as compared to the high-heat flux levels. In low gravity,

the vapor bubbles adhered to the heater surface and were 1 cm to 5 cm in diameter. In normal gravity, the vapor

bubbles lift off the heater surface due to buoyancy and are approximately 1.5 mm in diameter.

The flight hardware was flown on STS-57 mission in June 1993. Eight of nine test points were successful. The

Pool Boiling Experiment was flown again on the STS-60 mission, in February 1994. All nine test points were

successful.

The principal investigator submitted the final report on the results of the STS-47 mission to NASA-Lewis in July

1994. A combined final report of the STS-57 and STS-60 missions should be completed by January 1995.

The results from these three flights can be summarized as follows:

In microgravity the absence of buoyancy causes large bubbles to form and often remain on the heater surface as

surface tension plays a dominant role. Some dryout and rewetting was observed. In normal gravity (lg) convection

causes the bubbles to depart from the heater surface while they are quite small.

Correlation of dry out area to mean, h, and boiling, h_, (wetted) heat transfer coefficients and mean heater surface

temperature, Tw, for microgravity pool boiling tests is first of its kind.

Professor Merte successfully passed a Microgravity Hardware Reflight Reviews held on June 24, 1994 on his

proposed related experiment, "Study of Pool Boiling in Microgravity-Rewetting Following Dryout," was approved

by NASA based on favorable evaluations from peer review panel. Two flights are planned using the same pool

boiling hardware with a few modest changes. The tirst mission should occur in the spring or summer of 1995.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 2/90 EXPIRATION: 9/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-24-0B-10

MS Students: 1 MS Degrees: 1 RESPONSIBLECENTER: LeRC

PhD Students: 1 PhD Degrees: 1

11-9 4
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

.Journals

Merte. H. Jr. and Lee, H.S., Keller. R.B. "Pool boiling experiment prototype model flown on STS-47 (PBE-IA)," report

NASA contract NAS 3-25812. Report No. UM-MEAM-93-10. The University of Michigan, Department of Mechanical

Engineering and Applied Mechanics. lI)ecember, 1993).

NASA Tech Briefs

Lee, H.S. and Merte, H. Jr. Vapor bubble dynamics in microgravity, report NASA Contract NAS-3-25812. Report No.

UM-MEAM-93-10. The University of Michigan, Department of Mechanical Engineering and Applied Mechanics. NASA

Tech Brief, (December 1993).

Presentations

Merte, H. Jr. "Nucleate pool boiling in microgravity and variable gravity." Department of Chemical Engineering,

Clarkson University, Potsdam, New York. December 7. 1993.

Merte, H. Jr. "Nucleate pool boiling in microgravity - results from STS-47." NASA SSSAAS meeting (Space Station

Science and Applications Advisory Subcommitte) Houston. Texas, Feb. 16, 1994.

Merte, H. Jr, "Gravity effects on liquid/vapor phase change." Two Seminar Series presented in the Department of

Mechanical Engineering at McMaster University, seminar entitled: "Condensation Heat Transfer under High Gravity. and

Pool Boiling in Microgravity and Variable Gravity, Hamilton. Ontario. May 11. 1994.

11-9 5
[I. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

Surface Tension-Driven Convection Experiment (STDCE-1, STDCE-2)

PRINCIPAL INVESTIGATOR:Prof. Shnon Ostrach Case Western Reserve University

CO-INVESTIGATORS:

Prof. Y. Kamotani Case Western Reserve University

TASK OBJECTIVE:

The objective of this research is to further the understanding of the physical mechanisms associated with

non-oscillatory (STDCE-1) and oscillatory (STDCE-2) thermocapillary flow by (a) developing an accurate

description of the physical mechanisms, (b) developing an accurate numerical model, and (c) obtaining ground-based

and flight experimental data to verify the physical mechanisms and the numerical model. The thermocapillary flows

result t.rom the fluid motions generated by the surthce-tractive force that is caused by surface-tension variation due to

the temperature gradient along the tree surface.

TASK DESCRIPTION:

STDCE-I: The basis of Surface-Tension-Driven Convection Experiment 1 (STDCE-I) flight experiment is a

copper test cell 10 cm in diameter and 5 cm deep, filled with silicone oil, able to provide both flat and curved tree

surfaces in a microgravity environment. The outer wall of the test cell is water cooled. The silicone oil can be

centrally heated either externally by a carbon dioxide laser (constant heat flux, CF) or internally by an immersion

heater (constant temperature, CT). The cross section is illuminated by a 1-mm-thick sheet of light, which scatters

from small aluminum oxide particles mixed into the oil, allowing observation and measurement, using a

particle-tracking technique, of the axisymmetric flow velocity. An infrared imager is used to measure surface

temperature, and thermistors are used to measure fluid and wall temperature. The velocity and temperature

measurements are compared with the numerical predictions.

STDCE-2: The center of Surface-Tension-Driven Convection Experiment 2 (STDCE-2) is an interchangeable

module containing a test cell and fluid reservoir. Six modules containing copper test cells of 1.2, 2.0 and 3.0 cm

diameter, each with the depth equal to the radius, will be filled with 2 centistoke silicone oil, to provide both fiat

and curved tree surfaces in a microgravity environment. In three of the modules, one of each size, the fluid will be

heated by a carbon dioxide laser, imposing a Gaussian heat flux on the tree surface, and in the remaining three the

fluid will be heated internally by an axially located heater which is ten percent of the chamber diameter. The outer

walls of the test chambers will be cooled. This modular approach was taken to accommodate the large test matrix.

During the experiment, the surface temperature--which is the driving lorce in the flow--is measured

non-intrusively by an infrared imager. The free-surface deformation, felt to play a critical role in the oscillation

phenomenon, is measured quantitatively using a Ronchi deflectometer. The flow field is observed by illuminating

the entire test chamber volume with laser light which is scattered from 20 micron aluminum oxide particles mixed

in the fluid, allowing for three-dimensional qualitative visualization. Thermistors are used to measure bulk fluid,

wall and heater temperatures.

At the start of each test the heater power will be slowly increased until the flow transitions from steady and

axisymmetric to periodic and three dimensional. This will be pertbrmed lot 43 combinations of test chamber size,

heating mode and free surface shape. The temperature difference at the transition point will be used to calculate

non-dimensional parameters which are used to characterize the onset of oscillations. The flow field, surface and

bulk temperature distributions, and the free surthce defbrmations will be correlated to support the proposed physical

mechanism for the oscillatory phenomenon.

II Ill II I Ill i I I i I II III ii I I I i l I I I II I iii l i i I i i i ii I I I I I Ill I i II I I I i i I i i i i I I ii i i i i i i i I I I I I Ii i li l i i i I I I I I I l Ii I i I i I I i I I I It I ii i ii i I I I i I I I II It I i i I i I i i II I II I i i i i i i i I i i iI i I i i i I i i i I II I I i i i i I I eI I I II i i i i i i i i I I I I II i i i i i i i i i i I ei i i i i i i i i i i i i i i i i i i i i i i i ii i i i i i i i i

II-9 6
II. MSADProgram Tasks -- Flight Research Discipline: Fluid Physics

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TASK SIGNIFICANCE:

The Surface Tension Driven Convection Experiment is designed to study the nature and extent of steady and

oscillatory thermocapillary flows using state of the art diagnostics to measure and characterize these flows over a

wide range of parameters. V',duablc data, which can only be gained from low gravity-based experimentation, will bc

obtained resulting in an understanding of the fundamental physical mechanisms and improved implementation of

related industrial processes such as life support systems, containerless processing of materials, trysted growth,

propellant storage management, and bio-l]uid,s engineering both in space and on earth.

PROGRESSDURINGFY 1994:

STDCE- 1

STDCE-1 was flown on USML-1 in June, 1992. 38 tests were completed returning over 12 1/2 hours of data. To

date approxunately 75% of the data has been analyzed and compared to the numerical model. The comparisons show

good agreement. The analysis of the data has been broken into sections and numerous presentations of tlaosc

sections of the reduced flight data have been made. These include flow data li'om the 1 hr CT and CF tesls.

temperature data from the 1 hr tests, flow data from the shorter CT flat surface tests, and flow (lat_ from the shorter

CF curved surface tests. All of the data is presently being compiled by a graduate student for the fin:d comract

report. In addition, no flow oscillations were observed in any of the tests corroborating the Principal Investigator's

theory that the Marangoni number alone is not suflicient to indicate the onset of oscillatory llow.

STDCE-2

Flight Experiment:

STDCE-2 is scheduled to fly on USML-2 in September of 1995. In preparation, the PI and Co-I participated m two

USML-2 Investigator Working Group meetings at the Marshall Space Flight Center in addition _) _tume_ot,s

meetings and reviews at the Lewis Research Center.

Ground-based work:

1. Analysis

A scaling analysis of axisymmetric thennocapillary flows was conducted. Various important velocity and length

scales were determined. The scaling laws were shown to agree well with the results of a numerical ;_natvsis. Based

on the scaling analysis a surt_tce deformation parameter (S-parameter) was derived for each CT and CF hcatJng mode.

Both Marangoni number and the S-parameter must be larger than certain values in order to obtain oscdlatory

thermocapillary flow. The work has been written up as a Ph.D. thesis.

2. Experimental Work

The deformation of the tree surface has been measured in oscillatory thermocapillary flow. The free surface motion

was measured by observing the surface in one radial cross-section through a micro-video system. An organized tree

surface motion was found. The frequency of the tree surface oscillations was the same as that of the temperature

oscillations detected by a thermocouple probe in the fluid. Both oscillation patterns were closely related.

An optical system is being set up to measure the free surface motion over the entire free surface instead of on

section. This optical measurement will provide us with information regarding a wave-like molion of the free

surface. The information is important in establishing a coupling among the surface motion and the rotating

temperature oscillation pattern.

An experiment on oscillatory thermocapillary flow in cylindrical containers is being performed. The objective is lo

confirm the S-parameters obtained by analysis. In o_der to do so the effect of buoyancy on oscillatory

thermocapillary flow must be understood. The buoyancy effect is being investigated numerically and

experimentally.

11-97
q

I1. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION; 4/91 EXPIRATION; 3196

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-25-0D-09

MS Students: 1 MS Degrees: 3 RESPONSIBLE CENTER: LeRC

PhD Students: 3 PhD Degrees: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Kamotani, Y., Ostrach, S and Pline. A. Analysis of velocity data taken in surface tension driven convection experiment in

microgravity. Physics of Fluids A, vol. 6, no. 11, 3601-3609 ¢1994).

Presentations

Chang, A. "Scaling analysis of thermocapillary flows in cylindrical containers." Ph.D. thesis, August, 1994.

Kamotani, Y., Ostrach. S. and Pline, A. "Some results from surface tension driven convection experiment aboard USML-I

spacelab." Paper AIAA-94-0238, 32nd AIAA Aerospace Sciences Meeting, Reno, NV. January 10-13, 1994.

Kamotani. Y.. Ostrach, S. and Pline. A. "Some Velocity Results from the thermocapiilary flow experiment aboard USML-I

Spacelab." COSPAR Meeting, Hamburg. German. 1994.

Kamotano, Y., Ostrach, S. and Pline. A "A thermocapillary convection experiment in microgravity." 1993 ASME Winter

Annual Meeting, New Orleans, LA, Nov.-Dec. 1993.

I 11141 H I I l aiiii i I I I I I l I I I I I II I I III III l lU Ii l lU|I ill I I I II I aI I I l oI I I I i i I Ill I I I I I I I I I ni U I l III I|l I I I I I mI I I II I |tl Ill I ll|ll I II I OI I I lllll|l I I oIII I| I I I I l I tl I lll I II |0 I| I n u|un n l I |hi |0 Iltl I I II hl I I I II l I I I n I |ll|ll lU I IIlll IlL ILL I||l|| I||I||IIHI|IIH

II-98
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

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Modeling and New Experiment Definition for the VIBES

PRINCIPALINVESTIGATOR: Prof. Robert L. Sani University of Colorado, Boulder

CO-INVESTIGATORS:

Dr. H. Azuma

Dr. T. Doi

Dr. S. Kamei

Dr. M. Ohnish

Dr. T. Kida

Dr. K. Yamamoto

Japanese National Aerospace Laboratory (NAL)

NSDA -- Japanese Space Agency

Mitsubishi Research Institute

Japanese National Aerospace Laboratory (NAL)

Japanese National Aerospace Laboratory. (NAL)

Japanese National Aerospace Laboratory (NAL)

TASK OBJECTIVE:

The Vibration Isolation Box Experiment System (VIBES) is an IML-2 flight experiment being designed by the

Japanese National Aerospace Laboratory. Its primary goal is to evaluate the perlormance of a vibration isolation

device in conjunction with typical fluids experiments. The IML-2 flight experiment will contain two experimental

units: the Convection Diffusion Unit (CDU) and the Thermal-Driven Flow Unit. The purposes of the CDU

experiment (the one of interest herein) are to observe natural convection and diffusive transport in a micro-g

environment and to observe the effect of g-jitter with and without the vibration isolation due to the vibration

isolation box. The objective of this project is to provide numerical modeling for the CDU experiment for aiding in

design refinements and evaluation of terrestrial benchmark experiments as well as post-flight evaluation of the

experimental data.

TASK DESCRIPTION:

The numerical modeling will utilize a Oalerkin finite element algorithm lor the linear momentum, energy and

species balance equations using the Boussinesq approximation. This project will make comparisons of two codes

(PI's research code and a commercial code, F1DAP) in a transient, 3-D calculation to determine their efficiency and

accuracy. Timing comparisons will also be made between FIDAP and the research code. The numerical

experiments will include example cases with and without the test cell being subjected to g variation; both single

and multiple frequency variations will be considered. The numerical experiment will also consist of stmulating the

z-environment (to be provided by the Japanese research team) both inside and outside the isolation box.

Comparison of these results should "allow a quantitative assessment of the isolation capability of the apparatus.

TASK SIGNIFICANCE:

The microgravity environment available tor space experiments is not quiescent but is subjected to signiticant

background vibrations generated by aerodynamic and machinery vibrations, crew motion, etc. Such g-jitter can be

relatively random in orientauon and can attain significant magnitudes. There is a growing list of observations and

data analyses that demonstrate the existence of significant g-jitter episodes and their potential for having very

deleterious effects on many proposed flight experiments. A potential solution to this problem in the micro-g

environment is the use of vibration isolation for the experiments which require it. The assessment of such an

apparatus is one of the main thrusts of the research proposed in this project.

PROGRESSDURING FY 1994:

During this reporting period, the tollowing have been accomplished:

1. The development, testing and benchmarking of the semi-consistent mass finite element projection ",algorithm for

2D and 3D transient Boussinesq flow has continued.

a. The algorithm has been modified in order to include the option of utilizing as skew-symmetric form of the

advection operator as a prelude to the implementation of a variable time step capability. This option required the

um_u_of_g_q_q_n_u_n_u_u__D_u_n_u_n__u_n_u_q_nu_n_n_n_u_

I1-9 9
I|. MSADProgramTasks-- Flight Research Discipline: Fluid Physics

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implementation of an iterauve solution technique, bi-conjugate gradient stabilized, appropriate for unsymmetric

zdgebraic systems. This has been done and the algorithm has been tested and benchmarked against known solutions

existing m the literature as well as solutions generated via the commercial code FIDAP for a spin-up of a lid driven

cavity.

b. The development of a variable time step algorithm with local time truncation error control is currently being

pursued.

c. The inclusion of the capability to model additional fields, for example, concentration, is being addressed. Its

eventual complementation will be an essential tool in the definition of potential new ilight experiments focused on

the behavior of coupled fluids in a g-jitter environment.

2. Opumization and parallelization studies are underway.

a. Since the last progress report Prof. Sani has further improved the optimization of the algorithm as well as

initialized an investigation of the potential parallelization of the algorithm via domain decomposition.

3. Initial ttrne-varying gravity Boussinesq flow simulation has been done.

a. The simulation reported in the previous progress report has been completed and the results are being compared

with expertmental observations made by a Japanese research team.

4. Ongoing communication with the Japanese research team for VIBES has been maintained.

a. The data from the VIBES flight (IML2) experiment, i.e., video, accelerometer data, etc., ,should be available in

the next few months and post-flight analysis of the data will be initiated.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 963-24-05-14

RESPONSIBLECENTER: LeRC

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II-I 0 0
|I. MSADProgramTasks-- Flight Research Discipline: Fluid Physics

Studies in EIectrohydrodynamics

PRINCIPALINVESTIGATOR: Dr. Dudley A. Saville Princeton University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

This research is designed to strengthen and test the experimental loundations of the theory, of electrohydrodynamics.

Electrohydrodynamic forces can be used to manipulate fluids, especially fluid interfaces. As such, they offer a

means of controlling fluid motion on very small length scales.

TASK DESCRIPTION:

Theoretical studies will center on adapting the existing leaky dielectric theory for the stability of a fluid cylinder to

account tor pinning the contact line at the upper and lower boundaries in a liquid bridge conliguration.

Experimental studies will be carried out to (1) evaluate the influence of ionic surlactants on conductivity so a.s to

enable us to control the time scale of the electrohydrodynamic fluid motion and (2} test the existing

electrohydrodynamic theory for the stability of a cylinder subject to an axial field with isopycnic systems.

TASK SIGNIFICANCE:

Despite substantial efforts over the past two decades, the foundation of electrohydrodynamics is weak. Relatively

few experiments have been done to test the leaky dielectric theory, the most promising model of behavior, and

much of the work has been of limited scope because of the need to use isopycnic systems to aw)id sedimentation

and hydrostatic pressure effects. This restricts the range of fluid properties that can be studied and as a result there

are many gaps in our knowledge. In addition to its scientific importance, there are a wide range of applications

where electrohydrodynamic phenomena play tmponant roles.

PROGRESSDURING FY 1994:

Expertmental work:

1. We were able to identify an ionic compound with which enables us to control the conductivity of low dielectric

constant liquids. We studied the conductivity of castor oil contmning various amounts of the solute and showed that

the solution behaved as an ohmic conductor. The use of this system will enable use to control the time scale of the

electrohydrodynamic motion.

2. The initial stages of the collapse of fluid cylinders was studied and we showed that the lineanzed theory was

capable of representing the experimental results over the initial period. Unfortunately, the need to use very viscous

fluids to control sedimentation limited the range of our results.

Theoretical work:

We tested the existing theory for infinite cylinders against all the known asymptotic results and found that it was

internally consistent. The next task is to adapt it to liquid bridges (pinned cylinders).

II-101
STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASKINITIATION: 4/93 EXPIRATION: 4/96

PROJECTIDENTIFICATION:963-24-08-03

NASA CONTRACTNO.: NAGS-969

RESPONSIBLECENTER: MSFC
Mechanics qf Granular Materials

PRINCIPALINVESTIGATOR:Dr. Stein Sture University of Colorado, Boulder

CO-INVESTIGATORS:

N. Costes NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The objective of this research is to examine the use of microgravity to gain a quantitative understanding of the

mechanical behavior of cohesionless granular materials under very low confining pressures.

TASK DESCRIPTION:

Ground-based displacement-controlled triaxial experimenLs are conducted on a cohensionless granular material at the

lowest effective confining pressures possible, that do not result in material instability, to assess constitutive

properties, stability phenomena, and control parameters that will be applied to in-space experiments on 75 mm

(diameter) and 150 mm (length) right cylindrical specimens. The ground-based tests on stmilar-sized specimens are

conducted in the range 3.5-69 kPa, while the microgravity tests will be conducted at effective confinement levels in

the range 0.05-1.30 kPa.

The displacement-controlled mode of loading confined specimens was chosen mainly to maintmn overall

specimen-apparatus stability while strain-softening resulting from continuous or discontinuous bifurcation and

discontinuous deformation fields are allowed to take place. Optical and other noncontacting displacement-sensing

techniques are used to measure spectmen response during experimentation. Prescribed displacements are transmitted

in terms of loading, unloading, and reloading histories, while volume change is measured in "drained" tests, and

pore fluid pressure is measured in "undrained" isochoric tests. Confinement pressure is transmitted to the granular

material assembly through a thin flexible latex membrane surrounding the specimen. A subangular and unilorm

Ottawa quartz sand constitutes the specimen.

Specimens tested both in space and on ground will be subjected to nondestructive and destructive (thin-slicing)

testing to assess degrees of material unitorrnity and isotropy before and after experimentation. It appears that

instability phenomenon associated with specimens of certmn configuratior s result in curved internal surfaces of

localized deformation and high rates of dilatancy, whose structure depenc[_ on bifurcation mode.

TASK SIGNIFICANCE:

Specifically, the purpose is to study the influence of particle interlocking and other fabric properties on the strength

criterion near the effective stress space origin, i.e., can it be represented by a straight-line envelope passing through

the origin or does it have a curved shape with shear (cohesion or interlocking) or tensile strength intercepts. The

experiment will determine whether conhesionless granular materials under very low effective confining

pressures/effective stresses tend to dilate or contract regardless of their initial state of compaction, and whether their

mechanical behavior under relatively large displacement or quasi-static cyclic loading is according to conventional

constitutive theory. In addition, bifurcation and material instability phenomena resulting in formation of shear

bands, before and after peak strengths have been reached, will be studied. Based on terrestrial experiments and

theory, it has been found that critical hardening, strain-softening behavior, and shear band orientation are dependent

on confining stress.

II-1 0 3
PROGRESS DURINGFY 1994:

The progress in the MGM project during FY94 includes the following:

1. Design of the MGM apparatus;

2. Improved specimen preparation technique;

3. Improved optical-imaging system and measurement of specimen motion;

4. Improved analysis of specimen bifurcation instability conditions;

5. Improved constitutive analysis methods.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 9/97

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-24-08-05

MS Students: 1 MS Degrees: 1 NASA CONTRACT NO.NAS8-38779

PhD Students: 2 PhD Degrees: 0 RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Macari, E.J.P., Sture, S., and Runesson, K. Prediction of response of granular materials at low effective stress levels. J.

Get)technical Engineering, vol. 120, no. 7. 1252-1268 (1994),

Peric, D., Sture, S., and Runesson, K. Effect of pore fluid compressibility on localization in elastic-plastic solids. Int. J.

Solids and Stuctures, vol, 32, no. 4, (1994).

Proceedings

Peric, D.. Runesson, K., and Sture. S. "Effect of pore fluid compressibility on localization of elastic-plastic solids under

undrained conditions." Proceedings of the US National Congress for Applied Mechanics. Seattle. WA (1994).

i i i i iiiIi i iii ml! III I I Ill i i i II mI i i I ! I III i $ i Ill i IIIl! I llll I I I I I I I I II I | I I s I I I I I I I, ! !I I II ! I I ! I I I i I I II I II I ! II I mi i i i i i! i iii i ! |l Iii i ! ml oi i i i i i ii i Ill I II,I I |tl I I I I I I I I II I ! I I ! I I I I II II I I I I I I !illl ml ! ii i I| I o I i i ii I i i ! i iii i i ii ! Ill ! I I O! I III IIII1! i I Ill Ill ! I I I II ! I III I I !

11-104
Thermocapillary Migration and Interactions of Bubbles and Drops

PRINCIPALINVESTIGATOR:Prof. R. S. Subramanian Clarkson University

CO-INVESTIGATORS:

Dr. R. Balasubramaniam NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The objectives of the research are to experimentally measure the thermocapillary migration velocities and the shapes

of single and interacting gas bubbles, and liquid drops in a continuous phase under the action of an applied

temperature gradient. Comparisons between the observed velocities and shapes with those that are predicted from

theory, will be made.

TASK DESCRIPTION:

The general approach has been to conduct ground-ba_ed norm'd-gravity testing and to develop theoretical models of

the thermocapillary migration phenomena. The instrumentation and diagnostics are centered on the physics of

interest, namely, flow fields, temperature fields, and bubble/droplet velocities and shapes. The theories and

numerica.l models developed and verified with the 1-g data will be used to design and predict the results of the flight

experiment. Preliminary a.ssessment of flight data will also begin within FY94.

TASK SIGNIFICANCE:

The results from these bubble migration experiments are not only expected to advance our knowledge in the area of

surface tension driven motion, but are, in addition, relevant to severn applications with respect to space processing

of materials. Some examples of the latter include solidification, glass processing, and composite preparation. The

physics studied in the experimenLs offer a method by which undesirable void formaUon in metals and composites

can be avoided.

PROGRESSDURINGFY 1994:

There were a lot of activities on the flight project side. Activities were concentrated on preparing tor and in support

of the flight experiment in July 1994. These activities included participating in ground testing of the

engineering/flight models in Europe; in mission sequence testing of engineering models at KSC; providing test

plans t0r the low-g aircraft flights that took place in July; familiarizing the crew as to the science background of the

expertment; and attending various mission simulations at MSFC. During the course of the year, the Pl expressed

concerns about being able to inject single bubbles; about being able to extract bubbles; and about getting reliable

PDI data. During the actual mission in July, the injection and extraction systems performed well, but little useful

PDI data was obtained. The PI and his team are currently analyzing flight data results which will be reported on in

the next period.

Ground based research continued in the Pl's labs at Clarkson. Research was conducted in the following areas:

migration of a pair of bubbles in a vertical temperature gradient; the study of drops held fixed under the

simultaneous action of thermocapillary and gravitational effects; and the development of predictions of tree

convection due to transient gravitational fields.

II-1 0 5
II. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/90 EXPIRATION: 12/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-25-0C-61

MS Students: 1 MS Degrees: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 2 PhD Degrees: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Wei, H. and Subramanian. R.S. Interactions between two bubbles under isothermal conditions and in a downward

temperature gradient. Physics of Fluids A. A6.9, 1971-78 (1994).

Presentations

Forbes, Rashidnia. N. and Balasubramaniam, R. "Abel inversion of irregularly spaced discrete interferometric fringe data:

A geometrical approach," Division of Fluids Dynamics Meeting, American Physical Society, Albuquerque, New Mexico,

November, 1993.

Kondos. P.A. and Subramanian, R.S. "Buoyant flow driven by a time-dependent gravitational field in a two-dimensional

cavity." AiChE Annual Meeting, San Francisco. November 1994.

Subramanian. R.S., and Kondos. P.A. "Gas bubble dissolution and growth in glass melts." invited review, American

Ceramic Society Meeting, Indianapolis. Indiana. April 1994.

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11-106
If. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

o__o;_Do_|!_!!!!o_o__oo_e_o_!__el_|_aoo__!__eoa__o|_e!_I__|_a_s__!o||__|o__a_;_!____|_|!_|!o_!o_o__|_|__!|_ooo_I!__o_!|_!!_!o|!___o______!!!__!__e!__|!|!!_Be_____!__t___too_!__H_!__!__DO_oo_oo____|__H_o___|__|!_!__n!_o!!__!_!!!!___!!_m!_oI_

Drop Dynamics Investigation

PRINCIPALINVESTIGATOR: Prof. Taylor G. Wang Vanderbilt University

CO-INVESTIGATORS:

C.P. Lee

A.V. Anilkumar

A.B. Hmelo

H.J. Hussein

Vanderbilt University

Vanderbilt University

Vanderbilt University

Vanderbilt University

TASK OBJECTIVE:

The objective of this program is to understand the behavior of free drops, primarily by studying them in a

microgravity environment. The Drop Physics Module (DPM) operated in the Space Shuttle provides an

opportunity to address outstanding fluid-dynamics issues of rotating and oscillating simple and compound drops.

To maximize the return from this short on-orbit opportunity, ground-based experiments will be performed to verify

concepts and experimental techniques, and modeling will be done to select the parameters for the DPM experiments.

This investigation will use a triple-axis acoustic positioning chamber to study the static behavior and dynamics of

simple and compound drops as well as of liquid shells. Equilibrium shapes and the stability of rotating and

nonrotating drops, their associated internal flow patterns, and the centering force associated with shape oscillatory

dynamics of rotating compound drops--will be the principal scientific areas of interest.

TASK DESCRIPTION:

A variety of experiments will be pertormed in space. Compound drops and liquid shells will be formed to study

their oscillation modes and the effectiveness of those modes in centering the core. The interaction between the

acoustic field and the drops will be studied: the drops' static shape, the stability of distorted shapes, and the

generation of any flows in the liquid. The dynamics and stability of rotating drops near the point of fission will be

explored.

TASK SIGNIFICANCE:

This investigation uses the low gravity provided by the Space Transportation System, the working laboratory of

Spacelab, and the Drop Physics Module hardware to study large drops. Studying drops from 1-3 cm. in diameter

shows dynamic phenomena to time scales which can be observed by the experiment operator as well as captured on

high-speed film.

PROGRESSDURING FY 1994:

Due to the late arrival of the DPM video data, the reduction and analysis of most of the USML- l data was performed

in FY 94; three papers have been prepared using this data and have been submitted for publication. Support to the

DPM Project in the area of understanding tumble rotation progressed from flow visualization experiments at

Vanderbilt to preparations for torque measurements on the flight system at KSC.

One of the primary objectives of USML-1 was to perform careful experiments on rotating drops. The DDM results

from Spacelab-3 deviated from analytical and numerical predictions. The USML-1 results showed that flattening due

to acoustic forces would cause experimental measurements to deviate from theoretical predictions that assume a

spherical geometry; when the drops are spherical, there is no discrepancy. The results will be published in the

Journal of Fluid Mechanics (Oct. 94).

Another set of USML-1 experiments studied the tendency of compound drops to become concentric under the

influence of capillary oscillations. A compound drops is composed of two relatively immiscible fluids one totally

11-107
contained within the second fluid drop. Studies of both bubbles and liquid-liquid compound drops showed that the

core slowly oscillated about the center and a,tter several periods remained concentric. These results which can not be

explained by existing inviscid models were published in the Journal of Colloid and Interface Science.

A third paper ha,s been generated fl'om USML-1 sequences of oscillation and natural decay. The experimental results

were obtained using rotating and non-rotating drops with small but finite viscosities. The latter data agree with

current theory while the Ilattening inherent in a rotating drop caused deviation from the stmple models. This work

has been submitted to the Journal of Fluid Mechanics.

A major reason that the science return from USML-1 was less than expected was the appearance of an uncontrollable

rotation. In support of the DPM Project a team at Vanderbilt has been studying how the air moves inside the DPM

chamber under various combinations of acoustic signals. Flows were observed to be due to both to the quartz wind

from the individuals drivers as well as to the interaction of DPM's unique signals. The strength of the former is

larger and correlates with the weak DPM driver on USML-1. Characterization measurements of the torque on a

suspended ball in DPM-like chambers at Vanderbilt, the trainer at Marshall SFC, and the flight system at KSC are

being carried out.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 8/92 EXPIRATION: 7/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-24-04-01

MS Students: 3 MS Degrees: 2 RESPONSIBLECENTER: JPL

PhD Students: 1 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Jo,rnals

Lee, C.P. and Wang, TG. Acoustic radiation pressure. J. Acoust. Soc. Am., vol. 94, 1099-1109 (1993).

Wang, T.G., Anilkumar, A.V.. Lee, C.P. and Lin. K.C. Core-centering of compound drops in capillary oscillations:

Observations on USML-I experiments in space. Journal of Colitis and Interface Science. w)l. 165, 19-30 (1994).

Proceedings

Wang. T.G.. Anilkumar. A.V.. Lee, C.p and Lin, K.C.

USML-I drop dynamics experiment results.

"AIAA Paper No. 93-0252, (1993)." A preliminary analysis of the

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II-10 8
lI. MSAD Program Tasks -- Flight Research Discipline: Fluid Physics

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Colloid Physics in Microgravity

PRINCIPALINVESTIGATOR:Dr. David A. Weitz EXXON Research and Engineering Co.

CO-INVESTIGATORS:

Prof. P.N. Pusey The University of Edinburgh

TASK OBJECTIVE:

This experiment entails the study of the physics of colloidal particles in microgravity. It consists of two distinct

parts. The first deals with ordered structures while the second deals with highly disordered structures. The study of

ordered structures entails the growth of colloidal superlattices lormed with mixtures of different-sized particles. The

goal is to develop useful periodic structures using colloidal particles as precursors, through "colloid engineering."

The study of the highly disordered structures entails the tbnnaUon of fractal colloidal aggregates of much greater

extent than has ever been done, and the lormatlon of very weak structures that would collapse under their own

weight in normal gravity.

TASK DESCRIPTION:

The work within this effort will be ground-based research to study the formation of novel materials from colloidal

dispersions, and to study the physical properties of such materials. As part of the eflort, space experiments to be

carried out in a space shuttle middeck earner, will be defined. These experiments will utilize the laser light

scattering apparatus currently being developed at NASA LeRC.

The focuses of the ground-based experiments will be the study of colloidal superlattices formed from mixtures of

different-sized colloidal particles, the in-depth study of the formation of fractal colloidal aggregates, and the study of

granular particles fluidized in a gas. While considerable knowledge exists about the lormation or growth of fractal

colloidal aggregates, much less is known about the unique properties of these objects and the consequences of their

scale invariance. A major reason for this is the relatively small scale over which the aggregates exhibit scale

invariant behavior. By growing structures that are scale invariant over a much greater range of length scales, the

properties of these objects can be studied much more direcdy. This will provide the first detailed information about

the consequences of scale invariant structure on the properties of these materials.

TASK SIGNIFICANCE;

Very little is currently known about the structures of binary colloidal crystals, and these expertments will initially

be directed at determining the phase diagrams of the superlattices for mixtures of different sizes of particles. In

addition, virtually nothing is currently known about the kinetics of the formation of these superlattices, and about

their dynamics once they are formed. This will also be studied by these experiments. This will represent the t_st

in-depth study of the growth and properties of colloidal superlattices.

PROGRESSDURING FY 1994:

The necessary arrangements for the grant were put in place in June 1994. The SCR will take place on October 28,

1994. The investigators have developed plans for the experiments to be conducted in space. This plan will be

presented at the SCR. The ground-based research to support the flight experiment has just been initiated.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 3/94 EXPIRATION: 3/97

PROJECT IDENTIFICATION: 963-24-05-13

RESPONSIBLECENTER: LeRC

i i i I i i i Ii i I i i i iil i I I I I i I II I I i=I I i i I I I ii i ii i i i i I i i I i i i ii i i i i i i i i i i II ii i i i i i i i i I ii i i i i i i lil I Iii i i i ii I i III I I I III I i i I I I i i liii iII I III I I II I I I Ii i ii i i i i aI i i i i i I ii i i i i i i ! i i i i II III i i i ii i i i i i lii ii i i I i ! I II IIi i I i ii i i i i i i111111111 i II II I I I I II Ill II IiI I Ii i i liIi

11-109
II. MSADProgramTasks-- Flight Research Discipline: Fluid Physics

Study of Two Phase Flow Dynamics and Heat Transfer at Reduced Gravity

PRINCIPAL INVESTIGATOR: Prof. Larry Witte University of Houston

CO-INVESTIGATORS:

J.B. McQuillen NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The objective of this study is to develop and experimentally verify theoretical models that predict gas-liquid flow

regimes and their characteristics in reduced gravity.

TASK DESCRIPTION;

Reduced-gravity experiments will be conducted in NASA aircrati to measure the previously listed two-phase flow

parameters for a range of tube diameters, gas and liquid flow rates, and fluid properties. The gas phase for the

experiments will be air; the liquids to be employed are water, water-glycerin mixtures, and water-zonyl mixtures. A

theoretical modeling effort will be integrated with the experimental efforts.

TASK SIGNIFICANCE;

The purpose of this study is to achieve a better understanding--better predictability----of two-phase (gas-liquid) flow

in pipes to assist in the design of space-based power and thermal management systems and of the terrestrial-based

nuclear power plants and oil and natural gas pipelines.

PROGRESSDURING FY 1994:

A series of low gravity tests were conducted aboard the NASA LeRC Learjet in November and December 1994

using a 1.27 cm. inner diameter test section. The focus of these tests was to obtain additional data concerning the

characteristics of slug and annular flow. A new technique using a hot film anemometer to measure wall shear stress

was incorporated.

In February, the original PI for this ettort, Dr. Abe Dukler passed away. The University of Houston, with the

concurrence of the NASA technical grant monitor, named Dr. Larry Witte to succeed Dr. Dukler. NASA

Headquarters decided to de_ope the original plans for a space flight expertment into a ground-ba_d activity.

In April 1994, several tests were performed aboard the NASA JSC KC-135 yielding flow regime maps for air and

three fluids -- water, water-glycerin, and Zonyl-FSP/water in a 2.54 cm. inner diameter tube. Additional

measurements were made, both near the gas-liquid mixer and near the exit, of the liquid film thickness, void

traction, pressure drop and wall shear stress.

A 2.54 cm. inner diameter heated test section was designed and fabricated to extend the flow dynamics research into

microgravity two-phase heat transfer. The section is designed to obtain local, time-averaged heat transfer

coefficients along the heated length as well as instantaneous coefficients that can be correlated with the motion of

liquid waves or slugs. Resistance temperature elements (RTD's) are positioned between the heaters and the external

tube to estimate the internal wall temperature. A thin-film thermocouple, capable of response times as short as 103

milliseconds, is mounted inside the tube near the exit. A film thickness probe just after the exit is used to correlate

the temperature fluctuations with waves or slugs. A special mixer section is used after the heated test section to

obtain the mixing-cup temperature.

ltnt_t_t_tt_n_tt_tn_tt_t_at_tt_tt_n_Iutt_nt*_t_t_ttutn_tt_un_tt_t_t_n_t_tuu_t_ttt_ttn_ut_ttat_te_utt_t_ttg_u_n_t_Iutt_ttt_ttn_t_t_t_tt_j_t_t_t_

II-1 1 0
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/94

BS Students: 0 PROJECT IDENTIFICATION: 963-24-0A-35

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Bousman, W.S. and Dukler. A. "Studies of gas-liquid flow in microgravity: Void fraction, pressure drop, and flow

patterns." Presented at the 1993 WA ASME Meeting, New Orleans, November 1993.

Bousman, W.S. and Dukler, A. "Ground based studies of gas-liquid flows in microgravity using learjet trajectories." AIAA

paper 94-0829. presented at AIAA Aerospae Sciences Meeting, Reno, January 1994.

Bousman. W.S. and McQuillen, J.B. "Characterization of annualar two-phase gas-liquid flows in microgravity." presented

at the Second Microgravity Fluid Physics Conference, Cleveland. OH. January 1994.

II-1 1 1
In 5itu Monitoring of Crystal G_vwth Using MEPHISTO

PRINCIPAL)NVESTIGATOR:Prof. Reza Abbaschian, Ph.D. University of Florida

CO-INVESTIGATORS:

A.B. Gukhale

S.R. Coriell

l.J. Favier

University of Florida

National Institute of Standards and Technology (NIST)

CENG (France)

TASK OBJECTIVE;

The objective is to determine the morphological stability of solid/liquid interlaces and resulting macro and micro

segregauon patterns, and to determine the attachment kinetics at the freezing inter/ace deduced via measurements of

the growth-rate/intert_ce-supercooling relationship.

TASK DESCRIPTION;

To investigate the solidification behavior and stability of solid/liquid interlaces during the growth of pure Bi (a facet

forming material), and Bi "alloyed with small amounts of Sn, in 1-g and lag. The experunents were designed to

make use of the second flight of MEPHISTO on USMP-2 (3/94).

The expenmenks make use of the Seebeck technique to measure the interlace temperature in-situ and non-invasively

during crystal growth in both the ground-based and flight experiments. Both 1-g and I.tg experiments make use of

the measured resistance change across the sample to determine interfacial velocity and Peltier pulsing/'or

demarcation of the interface shape.

TAsK SIGNIFICANCE;

The first flight studied morphological stability in Sn alloyed with Bi (non-facet t'orming material), conducted by

French scientists as part of this collaborative study. The results of the second flight experiment will therefore

complement the results and findings of the first flight.

PROGRESSDURING FY 1994:

A comprehensive directional solidification experiment was recently carried out successfully on the USMP-2 mission

(STS-62) utilizing the MEPHISTO directional solidification t_tcility. The 14 day shuttle flight was launched on

Friday, M_trch 4, 1994. Using three samples processed in parallel, a total of 45 cm of dilute Bi-Sn alloys were

solidified directionally in microgravity under well controlled and well characterized conditions. Prior to the final

directional solidification, extensive measurements were performed on the samples, consisting of Seebeck

measurements to measure the solid/liquid (s/l) interface temperature, resistance measurements to track the position

of the s/1 interlace and thermal gradient measurements in the solid and liquid during freezing and melting. The final

solidification also included a procedure for marking the shape of the s/I inter/ace via mechanical perturbations, as

well as rapid quenching of a 2 cm section of one of the samples.

The expernnents were performed to gain a detailed understanding of the role of gravity driven convection during the

solidification of faceted materials. Two fundamental and interrelated aspects of the liquid to solid transformation

have been investigated: (a) Morphological stability of the solid/liquid (s/l) interlaces and the resulting macro- and

micro-segregation patterns and (b) atomic attachment kinetics at the freezing interlace, deduced via measurement of

the growth rate-interface supercooling relationship(s)

To achieve the goals of the project in a relatively short period, a three-pronged strategy lbr achieving the stated goals

was used: (a) Development of experimental apparatus for ground based kinetics and morphological stability studies

at University of Florida (UF), (b) Scienttfic and technical collaboration with the MEPHISTO teams at CENG and

II-1 12
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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CNES and (c) Analytical modeling of morphological stability and interlace kineUcs in collaboration with Sam

Coriell (NIST). Particular reference is 'also made to an extensive collaboration between the various scientific and

technical personnel from NASA-Lewis for developing a comprehensive flight program.

The research team at UF developed the facilities necessary, for ground based expertments to ensure maximum

conformity with the MEPHISTO space hardware. In addition, tour "campaigns" were conducted prior to the

USMP-2 mission (three on the MEPHISTO engineering model at CENG and one on the MEPHIS FO flight model

at CNES). Each campaign required three samples approximately 1 meter in length, which were prepared at UF

according to MEPHISTO specifications. The campaigns not only proved the integrity of the samples produced, but

'also provided valuable ground based data. which is currently being compared with the flight experiments.

Concurrently, NIST has carried out an_ytical modeling of the morphological stability of faceted solid/liquid (s/l)

interfaces for the "alloy system under investigation.

These flight experiments utilized a novel technique (termed the Seebeck technique) to measure the interlace

supercooling directly, non-invasively and in-situ (i.e. in real time during growth). The interface velocity was

measured by monitoring the resistance change across the sample, while the interlace shape was delineated by

subjecting the sample to electrical current pulses (for ground based studies) and mechanical perturbations (Ior t.t-g

studies) to cause a momentary demarcation of the interlhces.

Initi',d ground-based experiments were carried out using high purity Bi and dilute Bi-Sn alloys. Bi-Sn "alloys were

chosen to complement the experiments conducted by CENG/CNES on the first flight of MEPHISTO

(MEPHISTO-1): on this flight, dilute, non-faceted Sn-Bi alloys were used, while this research program (the second

flight of MEPHISTO, or MEPHISTO-2) used strongly faceted Bi- 0.1 at % Sn "alloys. In this manner, the results

of the two flights are being used to compare and contrast various fun "damental aspects of solidification without and

with a strong influence of atomic attachment kinetics, respectively, in the presence (ground-based studies) and

near-absence (_-g studies) of gravity induced convection. It is expected that this comprehensive investigation

approach will significantly further our understanding of key crystal growth parameters.

We further expect to use these data to test and improve many of the current solidification theories. In particular, the

interplay between morphological stability and intertace kinetics is not well understood at the present time. The

microgravity experiments will yield an integrated database involving interlace velocity/interface shape/interface

supercooling. Such data are important from both practical and theoretical standpoints. For example, a knowledge

of the transition from a taceted to a rough interlace (from the Seebeck data) and the interlhce shape (from

solute-dump-demarcated intertaces) under identical growth conditions has tmportant applications in practical crystal

growth situations: the information can be used to understand the correlation between defect generation and solute

banding. In addition, because the inlormation has been obtained in diffusion dominated conditions without the

overriding effects of gravity-induced thermo-solutal convection, meaningful tests (arid appropriate refinements) of the

current crystal growth theories can be made.

Two other spin-offs of the proposed program are worthy of note here: we will be able to obtain values of key

parameters, such as liquid diffusivities, via this investigation. In addition, the novel and non-intrusive technique

used to measure the interlace temperature can potentially be utilized for monitoring and controlling the space-based

single crystal growth of technologically important semiconductors.

We are currently analyzing the approximately 6 gigabytes of USMP-2 MEPHISTO data. During the mission.

extensive use was made of the telemetry commanding capability to modify and refine experimental procedures for

better scientific yield. Preliminary analysis of the data acquired during the first 28 hours of mission shows excellent

correlation of the Seebeck signal with melting/freezing as well as solute build-up/decay. Numerical calculations are

being carried out concurrently to correlate the Seebeck signal with thermal/solutal decay and hence to back calculate

an accurate value of the diffusion coefficient of tin in liquid bismuth.

II-1 13
If. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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STUDENTSFUNDED UNDER RESEARCH:

BS Students: 1

MS Students: 4

PhD Students: 0

TASK INITIATION: 1/90 EXPIRATION: 9/95

PROJECT IDENTIFICATION: 963-25-05-04

RESPONSIBLECENTER: LcR.C

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Abbaschian, R., Gokhale. A.B.. DeWitt, R., Cambon. G., Favier. J.J.. Coriell, S.R., and deGroth, IIl, H.C. "In situ

monitoring of crystal growth using MEPHISTO." Proceeding of the Microgravity Materials Science Conference,

Huntsville. Alabama, May. 1994.

Gadonniex, D., Gokhale, A.. amd Abbaschian, R. "Morphological stability of faceted solid/liquid interfaces in dilute

Bi-Sn alloys." Proceedings of the 32nd Aerospace Science Meeting, AIAA 94-0791, January, 1994.

iitl oelOllllle Oil ill IIIOlllllllla Ill lee Ill IIIiiii Ill Ill I i oi iI la i ill III i ii iii i ii aill Ill Ill Ilelllll ii l Io I Iiilell Ill i el III lee Ill ItlOIII III eiii III iiii Iii i el Ill ill Ill II I Ill I I III I Oil I iii Ill Ill Ill Ill ilolle Ill ilalla III Ill ilOllallOllallOlOOloalolellllel

ii-1 1 4
II. MSADProgramTasks-- Flight Research Discipline: Materials Science

Coupled Growth in Hypermonotectics

PRINCIPAL iNVESTIGATOR:Dr. J. B. Andrews University of Alabama, Birmingham

CO-INVESTIGATORS:

A. Sandlin

S. Coriell

National Research Council (NRC)

National Institute of Standard,_ and Technology (N-IST)

TASK OBJECTIVE:

The objective of this investigation is to gain a further understanding of solidification processes in immiscible 'alloy

systems. A portion of the study involves the development of a model for the coupled growth process in monotectic

systems. This analysis starts with the basic equations for diffusion controlled growth and avoids many of the

simplifying assumptions often utilized in smailar analyses. A parallel effort is underway to develop and refine

experimental techniques which will permit steady-state coupled growth of hypermonotectic composition samples to

produce aligned microstructures. The results from these experiments will then be compared to predictions from the

model and utilized to improve the model. In order to permit steady-slate coupled growth in hypermonotectic

composition samples experimentation must be carried out under low-gravity conditions.

TASK DESCRIPTION:

This project includes the major research tasks of theoretical modeling, selection of sample materials, selection of

ampoule materials, experimentation, data analysis, and development of ampoules for processing. In addition, the

project is concerned with the evaluation of current/light hardware for use in experimentation and with input into the

development of new hardware. Experimentaticm requires directional solidification of immiscible aluminum-indium

alloys under low-gravity conditions in order to avoid convective instability and promote steady-state coupled

growth.

TASK SIGNIFICANCE:

The significance of this project lies primarily m the scientific gains to be made in truly understanding the coupled

growth process in immiscible alloys. Many alloys in immiscible systems have great promise for potentml

applications in areas which include superconductors, magnetic materials, catalyst.z, and electricad contacts. However,

there are many details of the solidification process that are poorly understood for these _dloys because these details

are masked by gravity driven phenomena. This proiect is aimed at using the unique environment avmlable in space

to improve this understanding in order to make possible the production of new materials using specialized

processing techniques.

PROGRESSDURING FY 1994:

Major advances have been made in the development of a model lor diffusion- controlled coupled growth in

monotectic systems. Starting with the basic equations, the model has been developed without many of the

simplifying assumptions usually made in this area. We have found that some of these presumably valid

assumptions lead to a major restriction on the phase equilibria conditions for which the previous analyses are valid.

These restrictions are avoided with the newly developed model. In addition, the new model determines the volume

tractions of the phases in a self-consistent way. This factor may be quite significauH at higher growth velocities.

In the expernnental area, contact angle and chemical compatibility tests have led to the selection of A 1N and

sintered SigN4 as viable ampoule materials lot microgravity experimentation. Flight am[u)ule designs are nearing

the testing stage. Work has been carried out which validates the current model for morphological stability

conditions in hypermonotectic AI- In alloys. In addition, comtxosilional armlysis of ground processed

hypermonotectic Al-ln samples indicates convective instability is a maior factor impeding the establishment of

steady-state growth conditions. This ground based work has permitted the establishment of processing limits for

microgravity experimentation on the Al-In alloy system.

Ii-1 15
STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 963-25-08-09

NASA CONTRACT NO.NAG8-39717

RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Arikawa, Y., Andrews, J.B.. Coriell, S.R.. and Mitchell. W.F. "Modeling and numerical simulation of processes at a

hypermonotectic solidification front." Proceedings of the 6th International Conference on Experimental Methods for

Microgravity Materials Science, TMS, R.S. Schiffman and J.B. Andrews. eds., 13%140 (1994).

Cheney. A.B.. and Andrews, .Y.B. "The evaluation of ampule materials for low-g processing of immiscible alloys."

Proceedings of the 6th International Conference on Experimental Methods for Microgravity Materials Science. TMS,

R.S.Schiffman and J.B. Andrews, eds.,191-197 (1994).

Hayes, L.J.. and Andrews. J.B. Proceedings of the 6th International Conference on Experimental Methods lor

Microgravity Materials Science, TMS. R.S. Schiffman and J.B. Andrews. eds., 16%174 (1994).

Books

Andrews, J.B. "Solidification of Immiscible Alloys" in "Immiscible Liquid Metals and Organics." Edited by: L. Ratke

DGM Informationsgesellschaft, Verlag Press, pp 199-222, 1993.

Presentations

Andrews. J.B. "Coupled growth in hypermonotectics."

AL, May 24-25. 1994.

NASA Microgravity Materials Science Conference. Huntsville.

Andrews, J.B.. Hayes, L.J.. and Corieli. S.R. "Instabilities during coupled growth of hypermonoteclics." COSPAR 30th

Scientific Assembly, Hamburg, Germany, July 11-21. 1994.

Andrews, J,B., Hayes, L.J,. and Moss. C.B. "Factors influencing coupled growth in hypermonotectics." TMS Fall

Meeting. San Francisco. CA. February 27-March 3. 1994.

Arikawa, Y.. Andrews, J.B.. Coriell, SR., and Mitchell, W.F. "Modeling and numerical simulation of processes at a

hypermonotectic solidification front." TMS Annual Meeting, San Francisco, CA, February 27-March 3. 1994.

Cheyney, A,B, and Andrews. J.B. "The evaluation of ampule materials for low-g processing of immiscible alloys." TMS

Annual Meeting, San Francisco, CA, February 27-March 3. 1994.

Hayes, L.J., and Andrews, J.B. "The influence of convection on coupled growth in Al-In hypermonotectic alloys." TMS

Annual Meeting, San Francisco, CA, February 27-March 3, 1994.

lI-1 16
Effects on Nucleation by Containerless Processing

PRINCIPALINVESTIGATOR:Prof. Robert J. Bayuzick Vanderbilt University

CO-INVESTIGATORS:

W. Hofmeister

M. Robinson

Vanderbilt University

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The primary, scientific objective is to further the understanding of nucleation of solids from their melts. A

secondary olqiective is to determine if ground based method.s, such as drop tube processing, electromagnetic

levitation, and electrostatic levitation, are equally useful for containerlessly processing bulk samples of pure metals

as compared to electromagnetic heating and positioning in low Earth orbit. Within this secon "dary objective is a

focus on identifying and quantifying any possible technique specific factors that inlluence nucleation behavior.

TASK DESCRIPTION:

The presently existing containerless ground based methods are being used to study nucleation of solid from the

liquid. This includes drop tube processing, electromagnetic levitation, and electrostatic levitation. Since nucleation

is a statistical process, approximately 100 undercooling measurements are desired for each type of sample. This

number of measurements facilitates the interpretation of results through the application of statistical techniques.

Much care is taken in the measurement of temperature due to the sensitivity of the approach to the precision of the

measurements. Increasing and investigating the absolute precision is an important part of the experiments. The

precision affects the width of the distribution of undercoolings, which consequently determines the activation energy

for the phenomena. A large half-width of a distribution yields low values for the preexponential and exponential

factors in the nucleation equation, thereby indicating heterogeneous nucleation by mechanisms otlmr than contact

with a container. Comparisons of the data from the ground based and flight techniques give clues as to the nature ol

the nucleation of the solid from the liquid. Different processing methods have different environments and other

factors that may affect the amount of undercooling in bulk samples.

TASK SIGNIFICANCE;

Solidification processing is one of the most prominent methods for the production ot materials and most of these

processes begin with a nucleation step. The regime of nucleation known as deep undercooling, where liquids are

cooled considerably below their equilibrium freezing temperatures prior to the formation of solids, has become

particularly distinctive. With deep undercooling, a unique condition for microstructural development and control

exists and, therefore, a unique condition for improving and controlling the properties of materials exists. Hence, an

understanding of the rudiments of nucleation in the unique regime is most important.

PROGRESSDURINGFY 1994:

Results indicate fundamental differences in the nucleation behavior of the same sample types in the three ground

based processing techniques, drop tube processing, electromagnetic levitation, electrostatic levitation. For

zirconium, which has been processed by all three techniques, the distributions of undercoolings are "allnon-Gaussian

and clustered around the same undercooling but are wider for the electromagnetic levitator and the drop tube than for

the electrostatic levitator. With all three techniques, the distributions retain the same general appearance but shift

their centers to higher undercoolings (lower nucleation temperatures) as the material purity is increased from 99.8%

to 99.95%. This trend toward higher overall undercoolings but similar distributions was also observed for 99.995%

pure zirconium samples processed in the electromagnetic levitator. However, the 99.995% purity material did not

undercool as well in the drop tube as it did in the electromagnetic levitator, "although the shape of the distribution

was similar. For niobium, processing to date has been accomplished only in the drop tube. In this case

_o_I_I_I_Itv_I_I_o_I_t_B_s__i_o_l_1*_I_j_DI_o_e_t_I_D_I_t_I_I_o_*_iI_i_I_l_I

II-1 17
distributionsweremuchnarrowerthanforzirconium'although the percentage undercooling ior similar purity levels

was approximately the same.

Due to the presence of ultra high purity helium in the electromagnetic levitator, the cooling rate of the samples can

be changed by adjusting the flow of cooling gas. Two sets of undercoolings, one obtained at a cooling rate of 100

KEsec and the other at 20 K/see, have been produced for the same sample type. The shape of the distributions was

the same, but the higher cooling rate set of undercoolings was clustered around an undercooling 10 K higher than

the center of the lower cooling rate set.

The values of the preexponential factors and the activation energies in the classical nucleation rate equation affect the

distributions of undercooling data, A set of undercoolings distributed over a larger range has lower values, whereas a

set of undercoolings distributed over a narrower range has higher values associated with it. Thus, for zirconium, the

drop tube and electromagnetic levitator had lower associated values than did the electrostatic levitator. The

preexponential factors and activation energies tend to be higher as the undercoolings shift to higher overall values.

With zirconium, values for the preexponential factors and activation energies ranged li'om 108 to I013 and 13 kT to

24 kT, respectively. For niobium, these values were 1034 and 72 kT. Overall, the values obtained for niobium

much more closely approach the values predicted lot homogeneous nucleation as calculated by Turnbuil and Fisher

using classical nucleation theory.

The flight experiment in low Earth orbit using TEMPUS, all electromagnetic heater and positioner, resulted in only

one undercooling measurement lor zirconium. This undercooling was 160 K. Due to sample instability in the

facility, the experiments were prematurely terminated when the samples welded to the cage. However, even though

no results on the nucleation behavior of zirconium were possible due to the lack of data, thermophysical property

measurements can be obtained. The latent heat of fusion of zirconium was determined to be 14.5 kJ/mol whereas

values reported in the literature to date vary between 14.5 and 16 k.l/mol. In addition, the large surface oscillations

that occurred while the sample was molten should enable the deternunation of the surface tension and viscosity of

zirconium in the undercooled state. Surface analysis of the samples is being conducted using Auger Electron

Spectroscopy (AES) and Electron Spectroscopy for Chemical Analysis (ESCA) in order to determine the chemical

compositions of the surfaces of the samples.

Preparations and additions were made in order to ready MEL, another electromagnetic heating and positioning

facility, for flights in the NASA KC-135 aircraft. Nucleation t'requency experiments using MEL, will be conducted

in vacuum at a level of around 10_ tort. The results will complement and allow comparisons between the ground

based techniques.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 4/90 EXPIRATION: 6/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION:963-25-08-06

MS Students: 0 MS Degrees: 0 NASA CONTRACTNo.: NAG8-978

PhD Students: 1 PhD Degrees: l RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Morton, C.W., Hofmeister. W.H., Bayuzick, R.J.. and Robinson, M.B. A statistical approach to understanding nucleation

phenomena. Materials Science and Engineering, vol. A178, 209-215 (1994).

Presentations

Bayuzick. R.J., Hofmeister. W.H.. Morton, C.W., and Robinson. M.B. "Effects of nucleation by containerless

processing." NASA Microgravity Materials Science Conference, Huntsville. AL, May, [994.

IIiiiIIIill llIIIfIII IllII|IifIiii iiilIIIliiiii IIIiiiIIiii IIIiiiIifiiIIiiiiiiiiililiii iiiIiIiiIiIiii lIiiiiiiiI IIoIIIIii iIi ii|iI!IIIIiIII!$ if!iI|iii iiIOIIIlIIIiiIIiIII iiiiiIIiI oIiIIiiiIIill IIelliioIIIIiiiiIIIi iiii lllll IIIIllO IIIIIIiiiIIIIiIIIIIII

11-1 18
Alloy Undercooling Experiments in Microgravity Environment

PRINCIPALINVESTIGATOR: Prof. Merton C. Flemings MassachusetLs Institute of Technology (MIT)

CO-INVESTIGATORS:

D.M. Matson Massachusetts Institute or Technology (MIT)

TASK OBJECTIVE:

The objectives of this task are to perform solidification experiments on undercooling binary 'alloys. to compare

results of ground-based and microgravity experanents, and to examine effects of microgravity on solidification

behavior and microstructure characteristics.

TASK DESCRIPTION:

Through experiments applying direct, high speed, high resolution pyrometric and cinematographic measurements

during melting, undercooling and recalescence of nickel-tin binary alloys of different compositions, both on the

ground and in microgravity, collect thermal history, nucleation and growth history., and resulting solidification

microstructures.

TASK SIGNIFICANCE:

With experiments carried out in microgravity, it is expected to have improved specimen shape and stability and

reduced convection during cooling, resulting in the possibility of higher undercooling, less microstructure

alteration, reduced coarsening, and improved specimen observation in order to gain a complete understanding of the

solidification kinetics of undercooled melts, including: primary dendrite tip velocities; rapid thickening of primary

and secondary arms during recalescence; ripening, remelting, and solute redistribution; dendrite fragmentation and

grain refinement; primary phase solidification and ripening; and eutectic solidification with concurrent primary

phase ripening.

PROGRESSDURINGFY 1994:

Work during the current grant period has resulted in the successful completion of the preliminary preparations for

the tlight undercooling experiments and support of the IML-2 TEMPUS flight investigations. Samples have been

prepared, analyzed, and submitted for installation in the flight module. Preliminary investigations to define optimal

processing parameters were completed utilizing the NASA KC-135 experimental platform. All flight samples were

subsequently processed by melting and observing the solidification behavior in microgravity during STS-65 and are

presently under analysis following recovery from the orbiter payload compartment. Sample metallography and

experiment documentation are also currently in progress.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 4/90 EXPIRATION: 6/95

PROJECT IDENTIFICATION: 963-25-05-03

NASA CONTRACT NO.: NAG8-971

RESPONSIBLECENTER: MSFC

_D___u_n_D_n_nu_n_n_n_u_u_u_m_n_q_nu__n_n_g_n

ll-I 19
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

IIIIIIIIIIIItllUlllIMIIIIIIIIIllllll;lllnull';¢lllll'llllllmMllllH U tlllIBIIllllllllllllllllllllllllll;lllllllllllllt Iltllll H I|IIIIIIIIIla|IUIII .lllllllllllllllUlllllJll$11"lll;IH i iHllllll01111111111qnllllllllllnlllllllUllUlllJ

Compound Semiconductor Growth in Low-g Environment

PRINCIPALINVESTIGATOR: Dr. Archibald L. Fripp NASA Langley Research Center (LaRC)-

CO-INVESTIGATORS:

R.K. Crouch

W.J. Debnam

I.O. Clark

NASA Headquarters, Code UG (MSAD)

NASA Langley Research Center (LaRC)

NASA Langley Research Center (LaRC)

TASK OBJECTIVE:

The objective of the Langley flight progrzun is to determine the effects of gravity driven convection on the growth

and crystal properties of the compound semiconductor alloy, lead tin telluride which is miscible over the entire

compositional range. The electronic properties of this material are dependent on the ratio of the two, psedobinary,

components and consequently, the uniformity of an array of devices is dependent on good compositional control.

Lead tin teiluride is amenable to study for it is easily compounded; it has a relatively low vapor pressure; and there

is existing, though limited, literature on its growth and properties.

TASK DESCRIPTION:

This material was chosen for microgravity research for a number of reasons. Lead tin telluride is not only a useful

semiconductor material which "has been used for construction of infrared detectors and tunable diode lasers. It "also

has a phase diagram similar to other compound semiconductors of interest such as mercury cadmium telluride and

mercury zinc tenuride.

Lead tin teiluride is also interesting from a purely scientific point of view in that it is both solutially and thermally

unstable. Both the temperature gradients and the compositional changes in the liquid near the melt/solid interlace

produce density gradients which, in turn, produce driving forces for convection when coupled with gravity.

TASK SIGNIFICANCE:

"Earth based Bridgman growth of lead tin telluride has only produced inhomogeneous crystals that are a result of

strong convective forces in the liquid during growth. The temperature gradients are required for growth and the

solutal changes at the interlace are a fundamental property of the material system. However, for convection to occur

these gradients must be coupled to a gravational field. Growth in low Earth orbit offers an unique and fascinating

opportunity to study the effect of convection on this class of materials. The resultant gravitational force is not zero

in low Earth orbit hence convection is not completely eliminated but the fluid velocity, due to convection, will be

gready reduced.

Two flights are planned in the Advanced Automated Direction',d Solidification Furnace (AADSF). The primary

objective of both flights is to study the effect of gravity reduction, hence convection reduction, on the growth of

lead tin telluride. In one experiment the growth rate of the crystal will be changed in steps to test the effect of

varying the relative speed of the interlace movement and the fluid velocity. In the other experiment the Space

Shuttle will be rotated to vary the relative orientation of the gravity vector and the crystal growth axis. Both sets of

experiments are expected to affect the compositional homogeneity of the crystal.

PROGRESSDURING FY1994:

This years effort has continued on finalizing the AADSF furnace configuration and calibration. Lead tin telluride

has been grown in the flight prototype furnace. The newly designed calibration cartridge has been used for extensive

characterization of the AADSF furnace. Doped germanium samples, with interlace demarcation, have been grown in

the prototype AADSF for comparison to the calibration data. Numerical modeling of the furnace and samples has

11-120
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

n_i_"_|n_in_a6_"_"I"n_In_||_"l"n_I_n_n_u_|_i"1"_i_no_"_o_in_"_H_no_"_H_o_n_u_nnn_u_iinn_uo_o_ Hollll,o,,Ion,olHIIHl,¢no,mn$,,In,--n--n--n.n,ln,.H,nn,,l,.,,,nnll,.,ll,,,nl,ll,ll,H,.

shown remarkable correlation with experimental measurements on calibration samples and the marked germanium

samples.

A cartridge with a miniature, internal, pressure gauge was designed and tested in furnaces both at Langley and

Marshall. These tests not only measured the pressure as a function of set point temperatures over the different

thermal gradients but 'also measured the integrity of the cartridge seals and the rigidity of the cartridge a,s a function

of temperature and differenti',d pressure. Both the inconel and WC-103 carlndges have been evaluated.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/78 EXPIRATION: 9/98

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 693-80-07-01

MS Students: 1 MS Degrees: 0 RESPONSIBLE CENTER: LaRC

PhD Students: 3 PhD Degrees: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Rosch. W., Fripp, A.. Debnam, W.. and Pendergrass, T.K. Heat transfer measurements in the Bridgman configuration. J.

Crystal Growth. vol. 137. p. 54 (1994).

Proceedings

Fripp, A.L.. Debnam. W.J., Crouch, R.K.. and Clark. I.O. "Compound semiconductor growth in a low-g environment."

Microgravity Materials Science Conference, Huntsville. AL, /Vlay 24-25, 1994.

Books

Sorokach. S.E.. Simchick, R.T., Fripp, A.L., Debnam. W.J.. and Barber, P.G. "Characterization of Bridgman crystal

growth using radiographic imaging," in "Grain Boundaries and Interface Phenomena in Electronic Ceramics." Edited by:

L.M. Levinson and S-I. Hiiano The American Ceramic Society, Ohio, pp 379, 1994.

II-1 2 1
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

III I IIIIlll i II J a Ill I lllll II I III1,1111 II I I I I I I i i I I Ill I I I I lit I I I I I i llllllllllll I I I I I I II I IIIIIIII I I I I I I I I I I I I I l alllllllllll I I I IIIII iiii I I I I I II I II I I II I I III n llO i ii i i ii i ii a ii i el i ii I i iii iii iii ill i i I IIIIIIIIIIIIIlUlIIIIIInlUIIIIIIIIIIlllllltllIllll

Melt Stabilization qf PbSnTe in a Magnetic Field

PRINCIPALINVESTIGATOR: Dr. Archibald L. Fripp NASA Langley Research Center (LaRC)

CO-INVESTIGATORS:

W.J. Debnam

F.R. Szofran

A. Chait

NASA Langley Research Center (LaRC)

NASA Marshall Space Flight Center (MSFC)

NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The objective of this research is to further elucidate the gravity driven physical phenomena on the growth of the

alloy compound semiconductor, PbSnTe. This work, coupled with the past microgravity experiment with the

MEA and the existing flight program to grow PbSnTe in the AADSF, will form the most comprehensive set of

space processing expertmenLs performed todate.

TASK DESCRIPTION:

The effect of the gravitational body force on the convective properties of the 'alloy compound semiconductor,

PbSnTe, with that body torce modified by both reduced gravity and by magnetohydrodynamic (mhd) damping is the

subject under investigation. PbSnTe is an ideal material for this study in that it was the material of both a past

flight experiment and a planned 1996 AADSF experiment. Both of these experiments are without magnetic fields.

Subsequent experiments, both Earth based and in Space, using mhd damping will form a complete set of

experiments that will further elucidate the gravity dependent physical phenomena on the growth of this class or

materials.

The application of a magnetic field to PbSnTe growth will dampen convective flow. The anticipated results are that

even in the MSFC superconductor magnetic furnace the growth will not become diffusion controlled but that the

combination of magnetic field and low gravity environment will produce diffusion controlled growth.

TASK SIGNIFICANCE:

Numerical modeling is an integral part of this endeavor. Computer stmulation can aid in the design of the space

expermaent by its predictive capacity to optimize conditions for the growth. The key purposes of this portion of

the study will be to optimize the growth for both the Earth and the space experiments and to obtain an estimate of

the required magnetic field strength tot low gravity growth.

This proposed work will complete the set. It will compare the effects of convection, as modified by a magnetic

field, on the growth of this material both on Earth and in the Microgravity environment round in low Earth orbit.

PROGRESSDURINGFY 1994:

The progress within this first year of the research on the magnetic stabilization of PbSnTe consists primarily of

preparations for future quantifiable, modelable experiments.

Numerical modeling is an essential part of this program. The primary, thrust for modeling is within the Materials

Division at the Lewis Research Center. Modeling, both two and three dimensionaJ, will evaluate both the

sensitivity of the thennophysic_d parameters to determine if better measurements, in addition to electrical resistivity,

are needed and attempt to determine the combination of low gravity and magnetic field strength required to attain

diffusion controlled growth in PbSnTe. Preliminary modeling is complete. Diffusion controlled growth is

predicted, with modest magnetic fields, in microgravity but heavy mixing is predicted on Earth even with a five

Tesla field.

________________________________________________i____________________________________________________________________________________ l I O O l l lO OO lll I Oil II ll OO I OI IIIII II el Ill lllelllllllllll}lllllllllilllll

II-122
The ampoule configuration has been designed for ground based tests in the live Tesla magnetically stabilized furnace

at the Marshall Space Flight Center. Seven crystals have been grown to date, six with full magnetic field and one

with no field. The primary variable was ampoule pull rate. All crystals showed complete compositional mixing as

was predicted by the numerical modeling.

Additional modeling is underway to evaluate the ampoule diameter as it affects both viscous damping and extent of

flux line intersection. The effect of thermal gradient, both magnitude and shape, will also be evaluated.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/93 EXPIRATION: 9/95

BS Students: 1 PROJECT IDENTIFICATION: 963-80-07-05

MS Students: 0 RESPONSIBLECENTER: LaRC

PhD Students: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Fripp, A.L., Debnam, W.J.. Szofran, F.R., amd Chait. A. "Melt stabilization of PbSnTe in a magnetic field."

Microgravity Materials Science Conference, Huntsville. AL. May 24-25. 1994.

|INn||| OIt oel e e ! | e e i e | | e| | e! e t I e el e e! o |! e e | | e | | t ! ! e tt e | I i t ! | e ! | ! t ! e! ! | t t e t | | ! e! !e | !t i ! e i | e e t0 ! it ! | el e |1 | | i e !i | |! | ! | t !e t| | i t i ! |11 e i | | ie | | | it | ! ! | i| | | el | el | el e e i e it | e e| e ! e | | | | e t e i | i i e e ee | e! e t ! e t | e ! e e | |1 e |t e ! t e t | e ! t e ee e t I e t ! e |l | t Ie e ! e e t e !, | t ee ! !e

II-123
Gravitational Role in Liquid-Phase Sintering

PRINCIPAL INVESTIGATOR:Prof. Randall M. German Pennsylvania State University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The purpose of this research is to establish the gravitational role in liquid phase sintering with respect to both the

macro--scale distortion and phase separation, and the microstructura.l evolution over tune at elevated temperatures.

TASK DESCRIPTION:

The investigation has graduated to flight status, with 21 samples (seven compositions of tungsten-nickel-iron)

subjected to liquid phase sintering treatments on STS--65 during July 1994. The experiments involved isothermal

hold times of 1, 15, and 120 minutes at 1500°C in the Japanese-developed Large Isothermal Furnace on the IML-2

mission. Identical ground- based experiments have been conducted to provide the baseline for contrast with the

microgravity samples, and post-flight analysis will locus on quantitative assessment of distortion and

microstructural evolution.

TASK SIGNIFICANCE:

The microgravity experiments will establish a modeling basis for the gravitational role in a viscous flow distortion

of sintered components. It will further assess the agglomeration of solid grains and possible coalescence

contributions to grain growth lor upgrading of current theories. These results will lead to the development of

manufacturing techniques which will permit formulation of new unique alloys.

PROGRESSDURINGFY 1994:

"Sintering" means welding or fusing of metal or ceramic powders by heating them without melting. Frequently, it

is aided by applying pressure in a special high-temperature press to squeeze the particles together. This experiment

explores a different mechanism, by adding a portion of a powder that melts at a lower temperature and surrounds the

powders that remain solid. This liquid then lets particles and materials move more easily, allowing the powders to

more rapidly form a solid compact. Problems such as separation of the solid and liquid due to gravity (manifested

by settling of the solid particles) still remain. Access to the low gravity environment of Earth orbit provides a

unique opportunity to study liquid-phase sintering without separation, settling, or other gravity-induced

complications. The results will increase our understanding of the process, and the new knowledge will help

introduce new industrial application of liquid-phase sintering, such as automotive components, resulting in new and

improved products.

In this investigation, mixed powders of tungsten, nickel, and iron are initially cold compacted under pressure in the

shape desired for the final product. The compacts are then heated to just below the nickel-iron alloy melting

temperature to provide handling strength, a process called "presintering." In the experiment, they are heated above

1465°C to form a liquid-solid mixture. The tungsten, with its very high melting point (3370°C), remains a solid,

while the nickel and iron, with much lower melting points, become liquid. The liquid permits more rapid transport

of material for faster sintering than would be possible if all the material were solid. After sintering, the

microstructure of the samples (i.e., the structure when viewed under very high magnification), consists of connected

tungsten grains surrounded by the solidified liquid.

This experiment flew as part of the second International Microgravity Laboratory (IML-2) mission in July 1994

aboard the Space Shuttle Columbia. The experiment was conducted in an apparatus called the Large Isothermal

Furnace (LIF), which could operate at the high temperatures required. The LIF was developed by

Ishikawajima-Harima Heavy Industries Co., Ltd., for the National Space Development Agency of Japan (NASDA).

II-1 2 4
lI. MSAD Program Tasks -- Flight Research Discipline: Materials Science

This project was supported by the NASA Headquarters Microgravity Science and Applications Division. and was

managed by the NASA Lewis Research Center.

The test specimens for the LIF consisted of three different cartridges, each contmning seven samples 10 mm m

diameter by 10 mm high. One cartridge was tested at each of the three critical sintering periods identified m earlier

ground-based expermaent:< 1, 15, and 120 minutes. In one minute, liquid penetrates along existing solid-solid

boundaries. Fifteen minutes is the time needed for full densificauon. The 120-minute nine is needed to observe

grain rotation and coalescence events.

In summary, a nominal temperature of 1506°C was achieved for each of the desired test tunes. Free-drift of

Columbia during the appropriate times was conftrmed. All of the functional obiectives were achieved. Analysis

will begin upon return of the samples to the laboratories of the Pennsylvania State University.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/94 EXPIRATION: 10/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-25-05-05

MS Students: 0 MS Degrees: I RESPONSIBLE CENTER: LeRC

PhD Students: 1 PhD Degrees: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Belhadjharnida, A., Johnson. J. L., Tandon, R. and R. M. German, Advances in liquid phase sintering. Journal of

Materials Synthesis and Processing, vol. 1, 275-285 (1993).

Proceedings

Heaney, D.F., R. M. German and I. S. Ahn. "The gravity effect on critical volume fraction in liquid phase sintering,"

Advances in Powder Metallurgy and Particulate Materials, vol. 2." Metal Powder Industries Federation. Princeton. NJ.

1993.

lacocca, R.G. and R. M. German. "Experimental design for liquid phase sintering in microgravity." Advances in powder

metallurgy and particulate materials, vol. 2." Metal Powder Industries Federation, Princeton. NJ, 1993.

Books

Heaney, D.F., German, R.M.. and Ahn. 1.S. "The gravity effect on critical volume fraction in liquid phase sintering," in

"Advances in Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton, N J, w)l. 2. pp

169-180, 1993.

Iacocca, R.G. and German, R.M. "Experimental Design for liquid phase sintering in microgravity," in "Advances in

Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation. Princeton. NJ, w_l 2. pp 181-194,

1993.

Iacocca, R.G., German, R.M., and Kidd, C. "Microstructural analysis of tungsten heavy alloy samples sintered in I-G

conditions: Preparation for shuttle flight," in "Advances in Powder Metallurgy and Particulate Materials." lVletal Powder

Industries Federation, Princeton, NJ, vol. 5, pp 201-218, 1994.

Heaney, D.F. and German, R.M. "New grain growth concepts in liquid phase sintering," in "Advances in Powder

Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton. NJ, vol. 3, pp 303--310, 1994.

Raman, R., Heaney, D., and German, R.M. "Control of component distortion during liquid phase sintering," in "Advances

in Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton. NJ, vol. 3, pp 281-293,

1994.

II-125
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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Isothermal Dendritic Growth Experiment

PRINCIPALINVESTIGATOR: Prof. Martin E. Glicksman Rensselaer Polytechnic Institute

Co-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

Successfully conduct the Isothermal Dendritic Growth Experiment (IDGE) on the STS-62 Space Shutde mission.

Analyze resulting space flight and terrestrial data to determine dendritic tip velocity and tip radius as functions of

supercooling (temperature). Use velocity and radius data to evaluate the validity of theoretical models, some of

which are nearly 50 years old, that purport to predict velocity and radius (these models are used to improve industrial

metal production on Earth). Publish reports and give papers to inform the scientific community of our findings.

TASK DESCRIPTION:

The Isothermal Dendritic Growth Experiment (IDGE) is a fundamental Materials Science experiment performed on

the Space Shuttle. The specific topic is dendritic solidification which is relevant to virtually all industrial

manufacture of metals and 'alloys on Earth.

IDGE will be performed in the cargo bay of the Space Shuttle using an apparatus designed, built, and tested at the

NASA Lewis Research Center (LeRC) in Cleveland, Ohio, USA. Over 400 photographs of dendrites that solidified

in space along with over 800 photographs of dendrites solidified on Earth will be produced on the first flight

(STS-62). Each photograph will be accompanied by 8 (or more) scientifically important measurements of time,

temperature, and local acceleration. While in space, IDGE will be operated by LeRC personnel located in the

Payload Operations Control Center (POCC) at the George C. Marshall Space Flight Center (MSFC) in Huntsville,

Alabama, USA.

In the months prior to the flight, we will make several trips to LeRC and MSFC for mission operations planning

and training. In addition, at RPI, we will analyze terrestrial data produced by the IDGE flight apparatus prior to its

turn over to Kennedy Space Center (KSC) personnel on July 28, 1993.

We will work with the LeRC personnel during the flight to assess the IDGE Slow Scan Television (SSTV) dendrite

images in real time and replan subsequent experiments to take maxm-tum advantage of circumstances.

After the flight, we will analyze the resulting 35mm photographs and other data to determine the dendrite tip

velocity and dendrite tip radius as functions of supercooling. These will be compared to predictions made by many

theoreticians over the last 50 years (these theories have been used to try to improve industrial metal production on

Earth).

As soon as possible thereafter, we will publish reports and give papers at relevant conferences to disseminate the

information to the scientific and industrial community.

TASK SIGNIFICANCE:

Ultimately, IDGE may result in improved industrial manufacturing of steel, aluminum, super alloys, and other

metals that we use on Earth every day. Moreover, the data returned from space will remain relevant indefinitely. In

/act, the Schriffer Committee report (1987) declared that IDGE was one of NASA's tour "world class" microgravity

science experiments due to the quality, scope, and long term relevance of its science.

IDGE will study Dendrites. Dendrites are tiny crystalline structures that form inside molten metal alloys when they

solidify during manufacture.

! I ! * 81 | I I I IJ I I ! I I I I | I ! | I I I !s I !| ! I I I I I I I I | ! | s o| |I I ! o i | I e I i | | |I | | | I e | | i | | I I, ! I I I I I I I I I I, | i. I I e i i. | I I! I I ! i * | i I i i, I!, II * I t I | o, |i i |I I I ¢ I | ! I I I I I | i i i i i, | I, | i I i | J i | ii _ i | i | | i | | | | |I I | i I l I I | | J I | i i| i I I I | | I I I! I * I I I I I o I I !I I |i i ! J i | ! I | I| ! i| i i | | i | | | | | |i | |i | | o I !

11-126
In summary IDGE is significant because:

Dendritic growth is the ubiquitous form of crystal formation encountered when metal 'alloys and many other

materials solidify. Most industrially important metals ($Billions) solidify dendritically from the molten state.

Examples: Cast iron "alloys and c_tst aluminum alloys used in automobile engine blocks.

The dendrites formed inside 'alloys during manulacture result in microscopic zones of strength, weakness, ductility,

and brittleness. Consequently, understanding precisely how dendrites form can lead to Improvement of 'alloy strength

and ductility by eliminating we',xk and brittle areas m the metal. Production costs can also be lowered.

IDGE provides the only unambiguous set of scientilic data that can be used to test and correct the theoretical models

of dendritic formation used to improve 'alloy production. Data gathered on Earth are confounded by gravitationally

induced convective efl'ects.

During the past 50 years, numerous scientists have attempted to develop practical theoretical models to predict

nnportant dendritic growth parameters. However, years of experimentation on Earth has not produced a data.set

capable of testing the models to find out which one is correct (if any). This is due to the influence of gravity.

On Earth, dendritic solidification can be strongly affected by gravitationally driven convective currents in the molten

metal. These currents exist during virtually all industrially important metal solidification processes. However,

their effect on dendritic solidification cannot be accurately modeled without knowledge of dendritic solidification in

the absence of such currents.

The microgravity environment in space effectively turns off convection in the IDGE experiment. Extensive

non-advocate peer review indicated that a comparison between space experiment data and Earth experiment data is the

only practical way to separate the effects of convection from the underlying mechanisms of dendritic solidificatmn.

PROGRESSDURINGFY 1994:

The Isothermal Dendritic Growth Expertment (IDGE) is a tele-operated microgravity science experiment payload that

flew on the space shuttle Columbia STS-62 mission during March 1994. It was an outstanding success.

All preflight activities were conducted as planned. These included evaluation of terrestrially acquired IDGE data and

six trips to LeRC and MSFC for planning and training for flight operations.

During flight, teleoperation allowed us (RPI and LeRC personnel) to modify the experiment protocol and, thereby,

take advantage of unexpectedly fortuitous circumstances. Consequently, by one measure, IDGE obtained nearly 300

percent of the required data. Specifically: 58 dendrites were grown versus 20 required (290% success); the

supercooling (independent variable) dynamic range spanned 37 to 1 versus 10 to 1 required (370% success); resulting

measurement precision and accuracy was approximately twice as good as required for most measurements and met

requirements on all others.

Analysis of the flight data revealed that current theories need significant modification. Moreover, convection, both

on Earth and in space, may have greater effect than previously believed. These findings are unexpected and

immediately important to the science of Solidification and, longer term, to industrial alloy production (e.g., steel

and aluminum).

Our l_rst Joumal Article was received by Physical Review on March 23 (only 6 days after Columbia landed).

Subsequently, we have presented at 10 prestigious seminars and conferences including the 26th COSPAR at the

World Space Conference in Hamburg, FDR. Three proceedings publications are currently in press. Moreover, as data

analysis proceeds to greater depth, we are in the process of writing further papers.

11-127
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/88 EXPIRATION: 12/98

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-25-05-01

MS Students: 3 MS Degrees: 1 RESPONSIBLE CENTER: LeRC

PhD Students: 0 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Glicksman. M.E., Koss. M.B. and Winsa, E.A.

(1994).

Dendritic growth velocities in microgravity. Phys.Rev.Lett, 73(4), 573

Proceedings

Glicksman, M.E., Koss, M.B., Bushnell, L.T., LaCombe. J.C., and Winsa, E.A. "Space flight data from the isothermal

dendritic growth experiment." COSPAR '94 (in press) 1994.

Glicksman, M.E., Koss, M.B., Bushnell. L.T., LaCombe, J.C.. Kobryn. P., and Winsa. E.A. "The telle-operational

capabilities of the IDGE." 6th International Symposium on Experimental Methods of Microgravity Science. edited by

R.A. Schiffman and J.B. Andrews. The Minerals. Metals & Materials Society, 141. 1994.

Smith. R,N., Glicksman. ME., Koss. MB.. Bushnell. L.T., and LaCombe. J.C. "Experimental study of dendrite growth in

an undercooled melt under microgravity conditions." Heat Transfer session at the 1994 ASME Winter Annual Meeting in

Chicago next November (in press) 1994.

Presentations

Glicksman, M.E. "Dendritic growth in microgravity: IDGE flight 1." Aachen Foundry Institute, Aachen, FRG, 1994.

Glicksman, M.E. "Dendritic growth in microgravity: IDGE flight 1." DLR. Space Simulation Institute, Koln-Portz, FRG,

1994.

Glicksman. M.E. "The isothermal dendritic growth experiment: First results from USMP-2." Pittsburgh Chapter of the

ACCG, Pittsburgh, PA, 1994.

Glicksman, M.E. "The isoothermal dendritic growth experiment: First results from USMP-2." Microgravity Materials

Science Conference, Von Braun Civic Center, Huntsville, AL, 1994.

Gticksman. M.E. "Space flight data from the isothermal dendritic growth experiment." At the 26th COSPAR. Hamburg,

FDR, 1994.

Glicksman, M.E. "Space flight data from the isothermal dendritic growth experiment." Giesserei lnstitut. RWTH Aachen,

Aachen, FRG, 1994.

Glicksman, M.E. "The isothermal dendritic growth experiment: Implications of Theory." NIST, Gaitherburg, MD, 1994.

Glicksman, M.E. "Space flight data from the isothermal dendritic growth experiment: What have we learned'?." Materials

Engineering Department Seminar, Rennselaer Polytechnic Institute, Troy, NY, 1994.

Koss, M.B. "Preliminary results from the isothermal dendritic growth experiment ." At the Space Experiments Division

Awards Ceremony, NASA Lewis Research Center, Cleveland, OH, 1994.

LaCombe, J.C. "Dendritic Solidification in a Microgravity Environment." Joint meeting of the Eastern New York Chapter

of ASM International and the Hudson-Mohawk Section of TMS, Latham. NY, 1994.

I1-128
Evaluation of Microstructural Development in Undercooled Alloys

PRINCIPALINVESTIGATOR: Dr. Richard N. Gmgel University Space Research Association

CO-INVESTIGATORS:

W.F. Flanagan V_mderhilt Univcrsitv

TASK OBJECTIVE:

The objectives of this study are to be conducted m view of experiment and pertinent theory, and will. upon

completion, serve to enhance our scientific understanding of solidification processes. These include evaluating the

microstructural morphology, external and internal to the sample, as functions of undercooliug (AT), composition

(Co), and volume (V,,).

TASK DESCRIPTION:

A series of cylindrical lead-tin alloy samples, some 16mm in length and 8mm in diameter, have been contained m

quartz tubes and placed in a well controlled furnace. Nucleation of the solid is reduced by one of d_c monitoring

thermocouples when the desired undercooling, from 5 to 25K, is achieved. The sample is then met_flh_graphically

prepared and microstructural development from the point of nucleation is folh)wed. Paramelcrs which have been

varied are sample composition, degree of undercooling, _md, to some extent, sample size. This experimental

procedure has been paralleled by a m(xlelling effort which predicts the microstructural developmen! of a single

dendrite that is initiated at the upper surface and grows down into the undercooled melt. Model verification ha_s been

complemented by direct observation of the solidificatioi_ process using sun,pies based on the transparent, metal

analogue, succinonitrile-water syslem.

TASK SIGNIFICANCE:

The mlcrogravity environment of space is envisioned as a novel processing arena tot the solidification ol metals and

"alloys. Contamination of high temperature and/or reactive materials is expected to be minimized as a container is

not required to hold the melt and the samples are not limited in size. Greater undercoolmgs might also result due to

elimination of heterogeneous nucleation sites with the subsequent solidification microstructure expected to consist

of extremely fine constituents and/or novel phases, i.e. improved material properties. Unfortunately, processing in

the microgravity environment is expensive and time consuming. Consequently, the intent of this work is to

conduct a thorough, ground-based investigation which will evaluate microstructural development m bulk,

undercooled alloys with the a_m of _Lscerlaining the advantage of processing in microgravity.

PROGRESSDURINGFY 1994:

Experimentally these include: 1) developing a technique to preterentially nucleate the undercooled liquid alloy. 2)

developing a computer model to follow the thermal history and microstmctural evolution after nucleation. 3)

successfully utilizing transparent materials to complement the metal alloys. Based on the computational and

experimental results a number of conclusions can be drawn. These include: 1) Upon nucleation, the solidification

velocity is initially very rapid, the dendritic and eutectic microstructure becoming finer as the undercooling is

increased. However, the undercooled s_unple heats up very quickly and the majority of growth takes place at

considerably less velocities. 2) Consequently, while the solidification microstructure is initi_dly fine it coarsens

rapidly as the velocity drops and is generally non-unitorm throughout the s_unple. 3) The best microstructural

uniformity is achieved in the s;unple with the least initial undercooling, i.e., 5K. Unfortunately the slow, but

relatively constant, growth was interrupted by fommlion of equiaxed grains which effectively served to destroy the

desired directionality of the sun,pie. Through use of the organic analogue, origin of the cquiaxed region observed in

Pb-Sn alloys likely occurs due to fragmentalion (not heterogeneous nucleation) and settling of dendritic y.rmns

which evolve at the point of nucleation. This detrimental quality would be minimized in a microgravity

environment. 4) Care must be taken when measuring primary dendrite growth velocities m uudercooled melts.

11-1 2 9
II. MSAD Program Tasks I Flight Research Discipline: Materials Science

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They do not grow at constant velocities, and what is measured may not -be a primary dendrite at all but the

continuation of secon 'dary arms intersecting the visible surtace. 5) While a microgravity environment may well suit

to process high temperature and/or reactive "bulk" materials, rapid heating of the liquid is likely to preclude

maintaining uniform, directionally fine, microstructures and/or significant amounts of an undercooled, e.g.,

peritectic, phase. A list of relevant publications, presentations, and an award notification foUows.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 12/91 EXPIRATION: 11/94

PROJECT IDENTIFICATION: 963-25-07-03

RESPONSIBLECENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Grugel, R.N. Microstructural evolution of primary dendrite trunks in directionally solidified, hypoeutectic.

aluminum-silicon alloys. Metallurgical Transactions A., (In press).

Grugel, R.N., Fay Hua, and T.G. Wang. Evaluation of the NaNO_ - Ba(NO_) 1 eutectic system for use in investigating

solidification phenomena. Journal of Materials Science Letters.. fin press).

Proceedings

Hua, F. and R.N. Grugel. "Microstructural evolution in undercooled Pb - Sn alloys: Composition and sample size effects."

Experimental Methods for Microgravity Materials Science: 6th International Symposium, 1994, TMS, eds., R.A.

Schiffman and J,B. Andrews, pp. 111-115.

Presentations

Grugel, R.N. "Appreciating gravity during directional solidification of metals and alloys." University of Missouri-Rolla,

April 20, 1994.

Grugel, R.N. and Fay Hua. "Using transparent materials to simulate soldification phenomena in metals - Microstructural

development in undercooled alloys." 8th Annual Alabama Materials Research Conference, 26-27 September 1994,

Tuscaloosa, AL.

Grugel, R.N. and Fay Hua. "Evaluation of microstructural development in undercooled alloys." Microgravity Materials

Science Conference, June 24-25. 1994, Huntsville, AL.

Hua, F. and R.N. Grugel. "Microstructural evolution in undercooled Pb - Sn alloys: Composition and sample size effects."

123rd TMS Annual Meeting, February 27 - March 3, 1994, San Francisco. CA.

Hua, F. and R.N. Grugel. "Microstructural development in undercooled aUoys." TMS Fall Meeting, October 17-21, 1993,

Pittsburgh, PA.

Hua, F., R.N. Grugel, and T.G. Wang. "Analysis of microstructural development during solidification in bulk, undercooled

Pb - Sn alloys." ASM-TMS Fall Meeting, October 2-6, 1994, Rosemont, IL.

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II-130
lI. MSADProgramTasks-- Flight Research Discipline: Materials Science

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Thermophysical Properties of Metallic Glasses and Undercooled Alloys

PRINCIPALINVESTIGATOR:Dr. William L. Johnson Calilornia Institute of Technology

CO-INVESTIGATORS:

D. Lee Calilbrnia Institute of Technology (Caltech)

TASK OBJECTIVE:

The objective is to study thermophysical properties of undercooled alloy melts and how they relate to glass

formation. Toward this end, we have developed non-contact calorimetric methods to investigate the specific heat and

thermal conductivity of these melts, both in the liquid and undercooled region. These quantities are essential for the

development of newer, more advanced processing technologies for both existing and future materials.

TASK DESCRIPTION:

Non-contact AC calorimetry was successfully demonstrated on the IML-2 flight in July, 1994. We obtained

information on the specific heat and thermal conductivity of liquid and undercooled Zr76Ni24 and Ni60Nb40 melts

using TEMPUS. This data is currently being analyzed to calculate entropy and tree energy functions tor these melts.

We will compare these quantities to their values for the corresponding equilibrium and metastable crystals to

compare the relative stability of the phases. Also, we will determine the Kauzman isentropic temperature of the

alloys and compare it to the observed glass transition temperature.

In addition, the ground-based total radiance bolometer is currently being integrated onto a UHV levitation chamber

for total hemispherical emissivity measurements. Measurement of temperature-dependent total henuspherical

emissivity functions will allow us to unwind specific heat from undercooling data in an unambiguous manner.

TASK SIGNIFICANCE:

The non-contact AC calorimetry experiment is significant for many reasons. First. the thermodynamic properties of

these advanced materials are a prerequisite to the development of processing technologies for them. Without

knowledge of heat capacities and thermal conductivities, it is not possible to define, for example, how much power

is needed to melt and cast the materials. In addition, the specific materials chosen lbr our experiment are the parent

compounds for a new class of bulk metallic glasses that have recently been discovered by our group here at Caltech.

By studying the properties of these parent compounds, we hope to better understand the bulk metallic glasses and

how they form. These materials will revolutionize metallic processing technologies with their novel, superior

properties. These materials can be engineered to be more ductile, slipperier, harder, lighter and more corrosion

resistant than the typical materials used today. It is essential that the processing technologies Ibr these materials be

developed as quickly as possible and that, therefore, the thermophysical properties be measured.

PROGRESSDURINGFY 1994:

The AC non-contact calorimetry method was successfully demonstrated on IML-2 in July, 1994. We were

successful in obtaining data tbr liquid and undercooled Zr76Ni24 and Ni60Nb40. This data is currently being

analyzed and should provide thermodynamic data not previously measureable. Preliminary measurements indicate

that the total hemispherical emissivity of an undercooled liquid changes by more than 20% between the melting

temperature and the glass transition, making the standard assumption of constant total hemispherical emissivity

through the undercooled region completely invalid. We will do these measurements Ior "allsamples flown on

TEMPUS.

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II-131
|I. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 2 MS Degrees: 0

PhD Students: 2 PhD Degrees: l

TASK INITIATION: 2/92 EXPIRATION: 6/95

PROJECT IDENTIFICATION: 963-25-08-07

NASA CONTRACT NO.: NAGS-954

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Lee. D.. Uffelman. D.. and Johnson, W. "Noncontact AC calorimetry of metals and alloys." Proceedings of NATO

Workshop on Science and Technology of Rapid Solidification. West Point. NY (1994).

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II-13 2
Il. MSADProgramTasks-- Flight Research Discipline: Materials Science

Orbital Processing of High Quality Cadmium Telluride

PRINCIPALINVESTIGATOR:Dr. David J. Larson, Jr. Northrop-Gmmman Corporation

CO-INVESTIGATORS:

A. Levy

DiMarzio

F. Carlson

J. Alexander

D. Gillies

J. Moosbrugger

Gmmman Research & Development Center

Grumman Research & Development Center

Clarkson University

University of Alabama, Huntsville

NASA Marshall Space Flight Center (MSFC)

Clarkson University

TASK OBJECTIVE:

The objective of this research is to investigate the influence of gravitationally-dependent phenomena (hydrostatic and

buoyant) on the growth and quality of Cadmium-Zinc-Tellunde (CdZnTe).

TASK DESCRIPTION:

Grow CdZnTe crystals in microgravity on USML-1/STS-50 using the seeded Bridgman-Stockbarger meth(xl of

crystal growth. Bridgman-Stockbarger crystal growth is accomplished by establishing isothermal hot-zone and

cold-zone temperatures with a uniform thermal gragient in between. The thermal gradient spans the melting point

of the material (1095 °C). After sample insertion the furnace's hot and cold zones are ramped to set-point

temperatures establishing a thermal gradient of 35 °C/cm and melting the bulk of the sample. The Ihrnace is then

moved further back on the sample, causing the bulk melt to come in contact with the seed crystal, thus 'seeding' the

melt. The seed crystal prescribes the growth orientation of the crystal grown. Having seeded the melt, the furnace

is thermally equilibrated and then the furnace translation is reversed and the sample is solidified by passing the

thermal gradient down the length of the stationary sample at a uniform velocity.

TASK SIGNIFICANCE:

The family of II-Vl compound semiconductors, of which CdZnTe is a commercially significant member, is used in

the fabrication of medium and long wavelength IR sensors and beta and gamma ray nuclear detectors. Orbital

processing offers the unique opportunity to significantly advance toward the goal of increased structural perfection

within bulk crystals of greater chemical homogeneity. The former results from solidification and post-solidification

cooling with little or no wall contact. The latter from the "damping of buoyancy driven convection and concomitant

growth of a homogeneous crystal under diffusion controlled growth conditions.

PROGRESSDURING FY 1994:

Two CdZnTe crystals were grown in the Crystal Growth Furnace (CGF) during the First United States Microgravity

Laboratory Mission (USML-1). These crystals were used for comparative analysis with terrestrial baselines (CGF

and commercial). The microgravity (g-g) and terrestrial (one-g) samples were quantitatively analyzed for chemical

homogeneity, opto-electronic performance (infrared transmission), and structural perfection.

Chemical homogeneity (macrosegregation) was predicted by the process model to be low for this alloy system, even

in one-g. This was conlirmed experimentally. Nearly diffusion-controlled growth was achieved in the CGF-size

samples (15mm OD). The effective redistribution coefficient (k_) of Zn in CdTe was reduced from ko=1.25 to k_

=1.10 in commercial-size boules (>40mm OD), demonstrating that careful experiment control can significantly

reduce macrosegregation terrestrially, even on a commercial scale. Longitudinal and radial segregation was

monitored in the flight samples. It was found that the solidification record was disturbed due to unanticipated

asymmetric thermal fields experienced by the flight samples. This will be corrected on the flight experiment to be

conducted on USML-2.

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II-1 33
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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FTIR transmission of both ground iuld flight materials was measured to be close to theoretic'd: 63% versus 66%

(theoretic'd). This suggested that both the ground and flight materials were close to the stoichiometric composition.

Infrared microscopy and x-ray me_Lsurements conlirmed that the principal precipitates were Te and their size (I-10

_tln) and density suggesled that both primary flight and ground base samples experienced similar cooling rates and

were close to stoichiometry.

The flight samples, however, were found to be much higher in structural perfection than the ground samples

produced in the same furnace under identical growth conditions except for the gravitational level. Rocking curve

widths were found to be substantially reduced, from 20/35 arc-seconds (one-g) to 9/15 arc-seconds (_t-g) for the best

regions of the crystals. The value of 9 arc seconds equals the best reported terrestrially for this material.

Morphologically, the ground samples were found to have a fully developed mosaic structure consisting of subgrains

and large regions of cross-slip, whereas the flight samples exhibited discrete dislocations and no mosaic

substructure or cross-slip was evident. The defect density was reduced from 50,000 -100,000 (one-g) to 500 - 500

(_t-g sample 1) and 1200 - 3000 EPD (_t-g sample 2). These, too, are the lowest reported.

The thenno-mechanical model suggested that the low dislocation density was due to the near-absence of hydrostatic

pressure in I.t-g which allowed the melt to solidify with minimum wall content, reducing the stress transmitted to

the crystal during growth and post-solidification cooling. Further, the highest quality material was predicted to be

on the periphery of the boule, unlike the terrestrial samples where the best material is at the core, and this was

conlirmed microstructurally.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 8/90 EXPIRATION: 10/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-21-08-02

MS Students: 3 MS Degrees: 1 NASA CONTRACT NO.NAS8-38147

PhD Students: 1 PhD Degrees: 1 RESPONSIBLI: CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Alexander, J.I.D. Residual gravity jitter effects on fluid processes. Microgravity Science and Technology, vol. 7, no. 2,

131-136 (1994).

Casagrande, L.G., Larson, Jr., D.J.. DiMarzio, D., Wu, J., and Dudley, M. The growth and comparison of large-diameter,

vertical Bridgman CdZnTe and CdTe. J. Cryst. Growth, vol. 137, 195-200 (1994),

Larroude, P., Ouazzani, J.. and Alexander. J.I.D. Symmetry-breaking flow transitions and oscillatory flows in a 2D

directional solidification model. European Journal of Mechanics B/Fluids, vol. 13, 353-381 (1994).

Larson, Jr., D.J., DiMarzio. D., Casagrande, L.G., Carlson, F.M., Lee, T., Steiner, B.. Long, G., Seller, D.G.. Wu, J., and

Dudley, M. Producibility improvemtns suggested by a validated process model of seeded CdZnTe vertical Bridgman

growth. J. Cryst. Growth, vol. 137, 11-20 (1994).

Larson, Jr.. D.J., Silberstein, R.P., DiMarzio, D., Carlson, F.M., Gillies, D., Long, G., Dudley, M.. and Wu, J.

Compositional, strain contour, and property mapping on CdZnTe boules and wafers. Semiconductor Science and

Technology, vol. 8, 911-915 (1993).

Proceedings

Alexander, J.I.D., and Rogers. M.J.B. "Passive accelerometer system: measurements on STS-50 (USML-I)." Proceedings

of the Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group, NASA

Conference Publication 3272. vo|. 2, 569-578. 1994.

Casagrande, L,G.. Larson. Jr,. D.J.. DiMarzio, D,. Wu, J,, and Dudley, M, "Growth of large-area, high quality, CdZnTe

substrates by the computer controlled vertical Bridgman method." SPIE Proceedings 2228: Producibility of II-VI

Materials and Devices. H.K. Pollehn and R, Balcerak. eds., 21-32, 1994.

II-1 34
DiMarzio. D.,Larson. Jr.,D.J..Casagrande, L.G.,Silberstein. R,P.,Wu.J,.Dudley. M., and Liao. P.-K. "Defect mapping

_f CdZnTe substrates." IRIA-IRIS Proceedings: 1993 Meeting of the IRIS Specialty Group (_n Infrared Materials, 69-84,

l)ecember, 1993.

DiMarzio, D., Larson, Jr.. D.J.. Casagrande. Wu. J.. Dudley, M., Tt_bin. S.. and N(_rton. P. "],arge area X-ray topographic

screening _I II-VI substrates and epilayers." SHE Pr_)ceedings 2228: Producibility _I" II-VI Materials and Devices. H.K.

Pollehu and R. Balcerak. eds., 5289-5300. 1994.

Dudley, M., Wu, J., Larson, Jr., D,J.. and DiMarzio, D. "Use of synchrotron white beam topography to characterize IR

detector manufacturing processing." Material Research Society Symposium Pr(_ceedings 324: Diagnostic Techniques for

Semiconductor Materials Processing, O.J, Glembocki. FH. Pollak, S.W. Pang, G, Larrabee. and G.M. Crean, eds.,

457-462, 1994.

Larson. Jr., D.J., Alexander, J.I.D., Gillies, D., Carlson. F.M., Wu. J.. and Black. D. "Orbital processing of high-quality

CdTE compound semiconductors." Proceedings of the Joint Launch + One Year Science Review of USML-1 and USMP-1

with the Microgravity Measurement Group, NASA Conference Publication 3272. vol. 1. 129-162, 1994.

Rogers, M.J.B., Wolf, R.P.. and Alexander. J.I.D. "Correlation of accelerometer data on STS-50 (USML-I)." Proceedings

of the Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group, NASA

Conference Publication 3272. vol. 2, 893-906. 1994.

Presentations

Alexander, J.I.D. "What factors determine the influence of spacecraft attitude motions, vibrati_n, and transient

disturbances _n convective transport in Bridgman systems?." COSPAR '94. Hamburg, Germany, July, 1994.

Alexander, LID. "Scaling and estimation of experiment response to g-jitter." FSA Physical Science Working Group

Meeting, ESA HQ, Paris. FRance, September 9, 1994.

Carlson, F.M., and Moosbrugger, J.C. "The role of thermal stress in vertical Bridgman growth of CdZnTe crystals." MAE

Department Seminar Series, Clarkson University, Potsdam, NY. September, 1994.

Carlson, F.M., Lee, T., Larson, Jr., D.J.. Long, G.. and Dudley, M. "CdZnTe c_'stal growth predictive modeling and

characterization." Gordon Research Conference on Cr'y'stal Growth, Andover, NH, July, 1994.

Carlson, F.M., Moosbrugger, J.C., Lee, T., and Larson. Jr., D.J. "CdZnTe crystal growth: predicitve modeling." ARPA

Intelligent Processing of Materials Workshop, Arlington. VA, November 12, 1993.

Casagrande, L.G.. Larson, Jr.. D.J., DiMarzio, D., Wu, J., and Dudley, M. "Growth of large-area, high quality, CdZnTe

substrates by the computer controlled vertical Bridgman method/ SPIE Meeting ou Producibility ot II-VI Materials and

Devices, Orlando. FL. April 5-8. 1994.

DiMarzio. D., Larson, Jr., D.J., Casagrande, L.G.. Wu, J.. Dudley, M., Tobin. S., and Norton, P. "Large area x-ray

topographic screening of II-VI substrates and epilayers." SPIE Meeting on Producibility of II-VI Materials and Devices.

Orlando, FL, April 5-8, 1994.

Dudley, M., Wu, J., Larson. Jr., D.J., and DiMarzio, D. "Use of synchrotron white beam top_graphy to characterize IR

detector manufacturing processes." Fall Meeting of the Materials Research Society, Boston, MA, November 29-December

3, 1993.

Fedoseyev, A., Alexander, J.ID., and Bessonov. O. "CNSPACK - Efficient solution of large sparse linear systems," First

Southeastern Linear Algebra Conference, Chattanooga, TN, May 27-28. 1994.

Fedoseyev, A., and Alexander, LID. "Numerical modelling of solidification under microgravity conditions."

International Aerospace Congress IAC '94, Moscow, August 15-19, 1994.

Klein, J., and Larson, Jr., D.J. "Comparison of theoretical and experimental performance of a PMZF furnace for

microgravity materials processing." Symposium on gg Solidification: Theory and Experimental Results, TMS Meeting,

Pittsburg. PA, October 1993..

Klein, J., and Larson, Jr., D.J. "Evaluation of solidification process control using a programmable multizone furnace

designed for microgravity materials processing." AIAA Space Programs and Technologies Conference and Exhibit,

Huntsville. AL, September 27-29, 1994.

Larson, Jr., D.J. "Orbital processing of Zn-alloyed CdTe.'* 44th International Astronautical Congress, Graz. Austria,

October 16-22, 1993.

ll-I 3 5
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

_iMl|_!_|_ii_i_iHm_i|_I_i_4_Q_mi_|_Qi_niiniinninii|M_i_n_i_i_n_i_i|_ Je_l|t |ll|l|l j_1_!ii_l_ii_a1_||_|_i_ii_lnn_n_i|i||i_i_**_i_i_!inni_|!_|_i|!_|_*t_t _lt|_t ||*l|101_n_t t i|liiil_ll_|!*tl_.l_

Larson. Jr., D.J. "Seeded CdZnTe vertical bridgman crystal growth and process model validation." Department of

Materials Science and Engineering Seminar. State University of New York at Stony Brook, March 23, 1994.

Larson. Jr., D.J., Alexander, J,I.D., Gillies. D.. Carlson. F.M.. Dudley, M. "Orbital processing of high-quality cadmium

telluride compound semiconductors." NASA Microgravity Materials Science Conference. Huntsville, AL, May 25-26.

1994.

Larson. Jr.. D.J., DiMarzio, D., Casagrande, L.G.. Carlson, F.M.. Lee, T., Steiner. B., Long, G., Seiler, D.G., Wu, J., and

Dudley, M. "Producibility improvements suggested by a validated process model of seeded CdZnTe vertical Bridgman

growth." SPIE Meeting on ProducibiLity of II-VI Materials and Devices. Orlando, FL. April 5-8. 1994.

Moosbrugger, J.C., and Levy, A. "Constitutive modeling for CdTe single crystals." Seminar on Microgravity

Solidification: Theory and Experimental Results, TMS Materials Week '93, Pittsburg, PA, October 18, 1993.

Moosbrugger, J.C.. and Levy, A. "Advanced constitutive modeling for CdTe single crystals." Poster presented at the

Gordon Research Conference on Crystal Growth, Andover, NH. July, 1994.

Moosbrugger, J.C., Levy, A., and Carlson. F.M. "Constitutive modeling for CdTe single crystals." ARPA Intelligent

Processing of Materials Workshop. Arlington, VA, November 12, 1993.

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II-13 6
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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Crystal Growth qf II-IV Semiconducting Alloys by Directional Solidification

PRINCIPALINVESTIGATOR: Dr. Sandor L. Lehoczky NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

F. Szofran

C. Su

R. Scripa

NASA Marshall Space Flight Center (MSFC)

NASA Marsh,all Space Flight Center (MSFC)

University of Alabama, Birmingham (UAB)

TASK OBJECTIVE:

The objective of this research is to investigate the effects of reduced gravity on the crystal growth of mercury zinc

telluride (HgZnTe) and mercury zinc selenide (HgZnSe) alloys with respect to their compositional, metallurgical,

and optical properties.

TASK DESCRIPTION:

The investigation includes both Bridgman-Stockbarger and solvent growth methods, as well as growth in a

magnetic field. The alloys are prepared by reacting pure, elemental constituents in evacuated, sealed, fused-silica

ampules. The crystals are grown in a multizone furnace. The hot zone is heated above the liquidus temperature of

the given alloy and the cold zone is maintamed at lower temperatures to provide temperature gradient sufficient to

prevent constitutional supercooling. Crystal growth is accomplished by slowly moving the ampule from the hot

zone to the cold zone of the furnace. The flight portion of tile investigation is being performed by using the

Crystal Growth Furnace (CGF). Preparation of the samples is being done in the Space Science Laboratory of

Marshall Space Flight Center, Characterization and analysis of the samples after processing is being done prtmanly

in the same laboratory with substantial microstructural analysis being done at the University of Alabama at

Birmingham. Device fabrication and characterization will be done primarily at the Rockwell International Science

Center.

TASK SIGNIFICANCE:

The anticipated results of this study will have both scientific and technological significance. The advancement in

science will result from the increased understanding of the role of gravity on the fluid dynamic and compositional

redistribution phenomena during the crystal growth of solid-solution semiconducting alloys having large separation

between the liquidus and solidus of the constitutional phase diagrams, and from the more accurate values of material

properties that can be measured using the high-quality, bulk crystals grown in space. Any advance in quality of

these electronic materials has a great technological impact because of the application to infrared detectors for NASA

and DOD requirements.

PROGRESSDURINGFY1994:

A series of HgZnTe crystal ingots has been grown from pseudobinary melts by Bridgman-Stockbarger type

directional solidification using the CGF Ground Control Experiment Laboratory (GCEL) furnace, as well as MSFC

heat pipe furnaces. Several ZnTe crystals were also grown using a Te-solvent zone growth method. Vtmous

thermal boun 'dary conditions and growth rates were employed and several of the ingots were rapidly quenched during

the steady-state portion of growth to establish correlation between thermal conditions and melt/solid interface

shapes. These experiments also indicated that the ingots can be successfully quenched and back melted to allow a

rapid return to steady-state growth. The fitting of the measured crystal compositional distributions to appropriate

theoretical models was used to obtain an estimate of the effective HgTe-ZnTe liquid diffusion coefficients. To a.ssist

the modeling of the pertinent heat and mass transport processes, selected portions of the pseudobinary phase

diagram, thermal diffusivity and melt viscosity have been measured. Heat capacity and enthapy of mixing Ior the

pseudobinary melts were calculated assuming an associated solution model for the liquid. Growth experiments for

i1-137
an Hg0_4Zn_ _6Te alloy crystal were also performed in a magnetic fieldthat showed significant fluid flow effects on

the crystal compositional distributions.

A ground preprocessed and quenched sample was successfully back-melted and partially regrown in the CGF

instrument during the first United States Microgravity Laboratory (USML-1) mission. The meitback interlace was

within 0.5 mm of the desired value. Because of the loss of power to the CGF, the experiment was terminated after

approximately 39 hours into the growth period. About 5.7 nun of sample had been grown at that point. Surface

photomicrographs of the recovered sample clearly showed significant topographical differences between the spaceand ground-grown portions. Compositional measurements along the sample axis indicated that the desired

steady-state growth for the axial composition was reached at about 3 mm into the growth. An X-ray diffraction and

SEM survey of the sample showed that both the ground- and flight-portions of the ingot contained only a few

grains, i.e., were nearly single crystals, and the crystallographic orientation was maintained following back-melting

and space growth. The interface shape, radial compositional variations, and the quenched-in dendritic structures of

the flight sample all have shown an asymmetric behavior. The compositional data strongly suggest that the most

likely cause was unanticipated transverse residual accelerations.

STUDENTS FUNDEDUNDER RESEARCH: TASK iNITIATION: 12/92 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 963-21-08-04

NASA CONTRACT No.: In-house

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Su, C.-H., Volz, M.P., Gillies, D.C., Szofram F.R.. Lehoczky, S.L, Dudley, M., Yam G.-D., and Zhou, W. Growth of

ZnTe by physical vapor transport and traveling heater method. J. Cryst. Growth, vol. 128. 627-632 (1993).

Palosz. W., Szofran, FR., and Lehoczky, S.L. The effect of heat treatment in the magnitude and composition of residual

gas in sealed silica glass ampoules. J. Crys. Growth, vol. 142, 215-224 (1994).

Proceedings

Lehoczky, S.L., Szofran, F.R., Gillies, D.C., Cobb, S.D., Su. C.-H., Sha. Y.-G., and Andrews, R.N. "Crystal growth of

selected H-VI semiconducting alloys by directional solidification." Proceedings of the Joint Launch + one Year Science

Review of USML-1 and USMP-1 with the Microgravity Measurement Group, N. Ramachandran, D.O. Frazier, S.L.

Lehoczky, and CR. Baugher, eds., NASA Conference Publication 3272, vol. 1, 163 (1994).

IIIgItIII llll IIIIIIIIeII!IIlllIIIIII OIIIIII IIIIlIIIIIlIIIIOIIII lIIIIIII lIIIIIII*IIIIIIIIIIIgIIIIIaIlaIloIla|IIII!IIIIIallanl lifo lOlllllllilliIllee lOoIII Oil III101 I11 ell OllellaI|* Ill Ill Illell eli leo |latl||IOt*ot *|**|**|*l|tt|enlnnisntt|_l_oe

II-13 8
II. MSADProgramTasks-- Flight Research Discipline: Materials Science

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Growth of Solid Solution Single Crystals

PRINCIPALINVESTIGATOR:Dr. Sandor L. Lehoczky NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

F. Szofran

D. Gillies

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The major objective of this research is to establish the limitations imposed by gravity during growth on the quality

of bulk solid solution crystals having large separation between their liquidus and solidus temperatures. The

important goal is to explore the possible advantages of growth in the absence of gravity.

TASK DESCRIPTION:

The alloy system being investigated is HgI.,C_Te with x-values appropriate for infrared detector applications in the

8 to 14(m region. Both melt and Te-solvent growth methods as well as growth in magnetic fields are being

considered. The study consists of flight experimentation and ground-based experimental and theoretical work needed

to establish material properties and optimum experimental parameters for the on-going flight experiment and to

assist material evaluation. Hg_.,Cd_Te is representative of several alloys which have electrical and optical properties

that can be compositionally tuned to meet a wide range of technological applications in the areas of sensors and

lasers with applications to optical computing and communications as well as the national defense. The

investigation includes both Bridgman-Stockbarger and solvent growth methods, as well as growth in a magnetic

field. The alloys are prepared by reacting pure, elemental constituents in evacuated, sealed, fused-silica ampules.

The crystals are grown in a multizone furnace. The hot zone is heated above the liquidus temperature of the given

alloy and the cold zone is maintained at lower temperatures to provide temperature gradient sufficient to prevent

constitutional supercooling. Crystal growth is accomplished by slowly moving the ampule from the hot zone to

the cold zone of the furnace.

The majority of the ground-based studies are being performed in Space Science Laboratory of the George C.

Marshall Space Flight Center. The flight portion of the investigation is being conducted using the Advanced

Automatic Directional Soliditication Furnace developed by the Marshall Space Flight Center and manifested for

flights on the United States Microgravity Payload series of missions. The ftrst flight of the instrument took place

in March 1994.

TASK SIGNIFICANCE:

The anticipated results of this study will have both scientific and technological significance. The advancement in

science will result from the increased understanding of the role of gravity on the fluid dynamic and compositional

redistribution phenomena during the crystal growth of solid-solution semiconducting alloys having large separation

between the liquidus and solidus of the constitutional phase diagrams, and from the more accurate values of

materials properties that can be measured using the high-quality, bulk crystals grown in space. Any advance in

quality of these electronic materials has a great technological impact because of the application to infrared detectors

for NASA and DOD requirements.

PROGRESSDURINGFY 1994:

Over the past several years, a detailed evaluation has been performed on the effects of growth parameters on the axial

and radial compositional uniformity, defect density, and optical properties in directionally solidified Hg_.,Cd_Te and

other similar compounds and pseudo-binary alloys. A series of Hgt.,CGTe alloy ingots (0<x<0.6) has been grown

11-139
frompseudobinary melksbyvertic_dBridgman-Stockbarger typheat-pipefurnaceassemblyusingawiderangeof

growthratesandthermal conditions.Several oftheexperiments wereperlormedintransverseandaxialmagnetic

fieldsof upto5T.Precisionmeasurements wereperformedontheingotstoestablishcompositional distributions

,roddefectdensitydistributmnslortheingots.Correlationbetweengrowthratesandthermal conditionsandgrowth

interfaceshapeshavebeenestablishedforthe',alloysystem.Toassisttheinterpretationf theresultsandthe

selectionofoptimumin-flightgrowthparameters, thepseudobinary phasediagram(0<_'-x<l), liquidandthermal

diffusivities(0<x_<0.3), meltviscosity, andthespecificvolumesasafunctionoftemperature(0<x<0.15) havebeen

measured. Fromthesemeasurements andotheravailabledata,theheatcapacity, enthalpyofmixing,andthe

thermal conductivityofpseudobinary meltshavebeencalculatedusingaregularassociatedsolutionmodelforthe

liquidph_tse.Aone-dimensional diffusionmodelthatreatsthevariationoftheinterlacetemperature, interlace

segregationcoefficient, andgrowthvelocityhasbeenusedtoestablisheffectivediffusionconstantsforthealloy

system.Theoretical models have been developed for the temperature distribution and the axial and radial

compositional redistribution during directional solidification of the "alloys. These were used along with the

experimental results to select the parameters for the t_st flight experiment flown on the Second United States

Microgravity Payload (USMP-2) mission. A microscopic model for the calculation of point-defect energies,

charge-carrier concentrations, Fermi energy, and conduction-electron mobility as functions of x, temperature, and

both ionized and neutral defect densities has been developed. For selected samples, measurements were performed of

electron concentration and mobility from 10-300K. The experimental data were m reasonably good agreement with

theory, and were successfully analyzed to obtain donor and acceptor concentrations for various processing conditions.

A live zone Bridgmzat-Stockbarger type furnace system designated as the "Advanced Automatic Directional

Solidification Fumace (AADSF)" has been designed and developed for operating in the cargo bay of the Space

Transportation System (STS). Over 15 growth experiments were performed in the development and ground-based

versions of the AADSF to establish optimum operating parameters and procedure for the initial flight experiment.

The experiment was successfully flown on STS62 mission as part of the Second United States Microgravity

Payload (USMP-2) mission m March 1994. An approximately 15 cm long and 0.8 cm diameter Hg0sCdo2Te "alloy

crystal was grown at a rate of 0.78 mm/h over a period of approximately 11 days. Preliminary x-ray radiographs of

d_e crystal indicate that the growth was successtul. Characterization of the crystal is in progress.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/84 EXPIRATION: 10195

PROJECT IDENTIFICATION: 963-30-01

NASA CONTRACT NO.: In-hou_

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

.lournals

Gobba. W.A. Patterson. JD.. and l,choczky, S.I,. A comparison between electron mobilities in Hg_.,Zn,Te and

Hg_,Cd,Te. Infrared Phys., vol. 34(3), 311 (1993).

Palosz, W.. Szofran, F.R., amd Lehoczky, S.L. The effect of heat treatment in the magnitude and composition of residual

gas in silica glass ampoules. J. Cryst. Growth, vol. 142, 215-224 (1994).
GaAs Crystal Growth Experiment

PRINCIPALINVESTIGATOR:Prot. David H. Matthiesen Case Western Reserve University

Co-INVESTIGATORS:

Dr. J.A. Kafalas

Dr. B.M. Ditchek

GTE Laboratories, Inc.

GTE Laboratories, Inc.

TASK OBJECTIVE:

The objective is to determine the magnitude of effects of buoyancy-driven convection on the crystal growth of bulk

gallium arsenide (GaAs).

TASK DESCRIPTION:

Selenium-doped (-10e-17 GaAs crystals are grown in controlled environments at selected environments affecting

fluid flow as follows: (a) low-gravity (minimal convection), and (b) normal gravity, in three separate orientations

(vector stabilizing the temperature gradients, vector destabilizing the thermal gradient, and vector transverse to the

thermal gradient), and a magnetically 'damped flow (the three normal-gravity orientations with either axial or radial

magnetic field). The distribution of dopant is measured and compared to numerical predictions. Selected electrical

_md chemical properties are measured and correlated with the dopant distribution. Both macro- and micro-segregation

;Lredetermined.

TASK SIGNIFICANCE:

Gallium arsenide (G'_), an electronic material, has two principle advantages over silicon for producing solid state

electronic "chip:" its ability to emit light, useful for making lasers, and its inherently high speed, useful in

high-speed computers, communication satellites, etc. To fully exploit these characteristics, the material must be of

the highest quality and be uniformly doped with traces of impurities. Typically, such uniformity is determined by

convection in the molten material from which GaAs crystals are grown.

This materials processing experiment, part of a larger effort to better understand and control the crystal growth

process, was undertaken to investigate the effects of buoyancy-driven convection on crystal growth.

PROGRESSDURING FY 1994:

The progress in FY1994 was very limited. This was due to the fact that the project is near completion and the

balance of the work for FY1994 will be to complete for the Final Report. This is expected to be released near the

end of the l-_scal year.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 1

MS Students: 0

PhD Students: 0

TASK INITIATION: 9/85 EXPIRATION: 4/94

PROJECT IDENTIFICATION: 963-21-05-02

RESPONSIBLECENTER: LeRC

11-141
Diffusion Processes in Molten Semiconductors

PRINCIPAl_INVESTIGATOR:Prof. David H. Matthiesen Case Western Reserve University

CO-INVESTIGATORS:

Dr. W. Arnold

Dr. A. Chait

Dr. B. Dunbar

Prof. D. Stroud

Case Western Reserve University

NASA Lewis Research Center (LeRC)

NASA Johnson Space Center (JSC)

Ohio State University

TASK OBJECTIVE:

To provide purely diffusive experimental measurements of the isothermal diffusion coefticients of Ga, Sn and Sb in

molten germanium with sufficient accuracy and precision to:

a) Differentiate between model predictions of the temperature dependence.

b) Determine the effect of dopant size and type.

c) Determine if a "wall effect" is present.

d) Provide input to continuum and atomistic model development.

To provide purely diffusive experimental measurements of the thermomigration diffusion coefficients of Ga, Sn and

Sb in molten germanium with sufficient accuracy and precision to:

a) Determine the effect of dopant size and type.

b) Determine if a "wall effect" is present.

c) Provide input to continuum and atomistic model development.

To develop a 3-dimensional, fully time dependent continuum numerical model of the germanium diffusion column,

shear cell, cartridge and furnace for both earth-based and space-based experiments which accurately predicts the

measured concentration profile as a function of distance in the diffusion column.

To develop atomistic models which accurately predict:

a) The purely diffusive isothermal diffusion coefficient of a dopant in a molten semiconductor,

b) The temperature dependency of dopants in molten semiconductors, and which:

c) Attempts to explain the "wall effect,"

d) Develops new empirical potentials useful for predicting other diffusion and transport properties for other molten

semiconductor systems.

TASK DESCRIPTION:

This program of study is directed at the fundamental and applied issues pertaining to diffusion of species in the

liquid state as driven by concentration gradients (Fickian diffusion) and thermal gradients (Soret diffusion). The

fundamental material systems of interest for near term study are the dilute binary systems of gallium (Ga), tin (Sn)

and antimony (Sb) in germanium (Ge). Systems of commercial interest for future study include the dilute binary

systems of dopants in gallium arsenide (GaAs). This research program consists of three major components: an

expertmental measurement portion, a continuum numerical simulation portion and an atomistic numerical

simulation portion.

The experimental measurement portion is designed to provide definitive measurements of the purely diffusive

component of mass transfer in molten semiconductor systems. A shear cell technique will be used to directly

measure the diffusion coefficients in semiconductor melts. For the Fickian diffusion case, isothermal measurements

will be used to determine the diffusion coefficients. An experimental matrix will be used to determine the

II-14 2
II. MSADProgram Tasks -- Flight Research Discipline: Materials Science

uui oaooI J i I oi i oi i in I uoi ain aoo unin I ol ai! I no I aoan|o II IInlanloultna OlllnloI aOI aOOal aI l an|o I I OI IOIII I nail0 UIO II OI I oIII I I I II Oil O0111 OI on aOHIO I I I OI Ill I OOI all aOlOll I I gI I l I I I! lull all I UI IIII I I Oil Ill 01ilia Ol I OIIOlllOlll Ill I IOI nonI IIIIOIIO I I HI|Ill Ill I III

dependence of the ditfusion coefficients on temperature, dopant type and column diameter. For the Soret diffusion

case, measurements will be made th a thermal gradient.

TASK SIGNIFICANCE:

The fundamental mechanisms of mass diffusion in the liquid state are still unclear to the degree necessary for the

prediction of diffusion of one species into another or even within itself. This observation is especially true with

respect to the dependency of diffusion mechanisms on temperature and on concenu'ation levels, ms well as on the

dopant type. Present estimates of diffusivity in molten semiconductors can typically provide an order of magnitude

estimate only, without any information on their dependency on concentration levels and types, and on temperature

and temperature gradients.

The availability of these data is of paramount maportance for practical reasons as well. The relevancy of numerical

modeling for the analysis and design of ground based and space experiments is directly dependent upon the accuracy

of the fundamental material properties used in these simulations. These data are also important for the correct

characterization and interpretation of experimental results from ground based and space experiments.

The subject of how a mass of one species diffuses through a mamx of another is, at the same time, both a very old

and very new research area. That this area can encompass the small, i.e.,movement of electrons in a plasma, to the

very large, i.e., the depletion of the global ozone layer, merely serves to emphasize the fundamental aspects of this

subiect. Most manufacturing technologies at some stage, rely on diffusion processes in the solid, liquid or gas.

The need for precise measurements of the diffusion coefficienLs in molten semiconductors has been repeatedly

pointed out. These data are required both to interpret the experimental results from previous space-based (and

Earth-based) • experiments and "also to optimize newly envisioned experiments. Difficulties in experimental

techniques and theoretical interpretations are cited for the lack of these data. This is a comprehensive program which

addresses both of these issues.

PROGRESSDURINGFY 1994:

Quantified the level of mixing between adjacent shear cell segn'nents due to the initial fluid-fluid shear.

• Numeric'ally evaluated shearing rate.

• Numerically quantified the effect of convection on the measured diffusion coefficient.

• Established machining tolerances for shear cells.

• Numerically evaluated Soret diffusion.

• Numerically evaluated the use of an applied magnetic field to suppress convection.

• Quantified error bars to establish confidence level in the measured diffusion coefficient.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: ]193 EXPIRATION: 2196

PROJECT IDENTIFICATION: 963-21-05-04

NASA CONTRACT NO.: NCC3-293

RESPONSIBLECENTER: LeRC

II-143
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

o J i i _ n i o i io i i| o J i o | i a i _ u; i uo i i o i J o i | o i is in i n i o i u o n i o ii J; i a _ |no | t u u J I =II o| I I o I J I n I o I i I o I! _ |III I I n I I I I J I *_ | Ia t | a I o I o I I I |_ I o I a o o a I I u o | uo II o I; o o n | In III a o| II o I I o I I * o I I I o oI o o o | o o | I o o o o o I! o II o. o |o | ul o || o t H _ o o o o _ ol I Io o o n o _ o o | |1 mI I o no o |no al .o u i _ n i _ o I

The Study of Dopant Se&_regaton Behavior During the Growth of GaAs in Microgravity

PRINCIPAL(NVESTIGATOR:Prof. David H, Matthiesen Case Western Reserve University

CO- INVESTIGATORS:

J. Kafalas Viable Systems, Inc.

TASK OBJECTIVE:

To characterize the two selenium doped gallium arsenide crystals which were grown in the Crystal Growth Furnace

(CGF) aboard the first United States Microgravity Laboratory (USML-1).

TASK DESCRIPTION:

During this task, the dopant distribution of the selenium in the grown gallium arsenide will be measured, Several

complementary techniques will be used including optical (infrared transmission FTIR and QIR); electrical (Hall

effect, C-V DLTS) and chemical (SIMS). In addition, NASA supplied acceleration measurements will be used to

correlate any segregation events present in the crystal.

TASK SIGNIFICANCE:

By cross comparisons of the optical, electrical and chemical measurements an exacting dopant distribution will be

measured m the crystal. When NASA supplies the appropriate acceleration data then, for the first time, an exacting

correlation will be made between the measured segregation events and any acceleration event.

PROGRESSDURING FY 1994:

The segregation measurements are nearly complete. These datat indicate that initially diffusion controlled growth

was achieved. However, after approxiamtely 1 cm of growth the data indicate that the segregation behavior

transitioned to that of complete mixing. The acceleration data is being examined for any causes.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: O BS Degrees: 0

MS Students: I MS Oe_ees: 1

PhD Students: 0 PhD Degrees: 0

TASK INITIATION: 5/92 EXPIRATION: 10/96

PROJECT IDENTIFICATION: 963-21-05-01

NASA CONTRACT NO.NAS8-39722

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Korpela. S.A., Chair. A.. and Matthiesen. D.H. l,aterial or radial segregation in solidification of binary alloy with a curved

liquid-solid interface. J. Cryst. Growth, vol. 137. 623 (1994).

Majewski, J.A.. and Matthiesen. D.H. Quantitative infrared imaging for the measurement of dopant distribution in gallium

arsenide. J. Cryst. Growth, vol. 137, 249 (1994).

Matthiesen. D.H. The total pressure of arsenic over molten gallium arsenide at 1260 °C. J. Cryst. Growth, vol. 137, 255

(1994).

Proceedings

Matthiesen, DH. "The study of dopant segregation behavior during the growth of GaAs in microgravity." Proceedings of

the Joint Launch + One Year Science Review of USML-1 and USMP-I with the Microgravity Measurement Group, NASA

Conference Publication 3272. 223-259 (1994).

I ! I OI I OOIIll I In OOOoOOOI oOOI oI OOOIi I IoOO0O0OOO0OO0OO011 OI I aoI ao! ooo ii oni ! oi i i i i i i! i io! i i i ei ao! I nI ooi I oI I oI uo! oo oooI oI oooooI IoI oooI Ol oI ! lull oI oooooOl oOl oois i I l I I oi oo |l ! ioo |oo | oI Ill l IOI I|11 |O I I OOOll O0OI I I OI SOI Ill I oa Oil Ill I O|I|O |OO I! I 0| Ill I|1 I I l lOl I

11-144
II. MSADProgramTasks-- Flight Research Discipline: Materials Science

Temperature Dependence of Diffusivities in Liquid Metals

PRINCIPALINVESTIGATOR: Prof. Franz E. Rosenberger University of Alabama, Huntsville

CO-INVESTIGATORS:

R. M. Banish University of Alabama, Huntsville

TASK OBJECTIVE:

This research alms at advancing the understanding of diffusion mechanisms in liquid metals and 'alloys through

accurate diffusivity measurements over a wide range of temperatures, including the proxmaity of the materials

melting points.

TASK DESCRIPTION:

Toward the above objective we are pursuing the following tasks:

• development of an efficient technique lbr dynamic in-situ measurements of diffusivities in melts as a function of

temperature;

• development of a flight-certified hardware package to automatically perform such diffusivity measurements under

reduced gravity conditions and on Earth;

• investigation of the significance of the "wall effect" in diffusion capillaries;

• exploration of convective contamination of the diffusivity measurements on Earth through numerical modelling;

• exploration of the possibility to simulate low gravity diffusion conditions in conducting liquids on Earth through

the application of magnetic fields;

• measurements of diffusivities of selected materials that will be chosen according to class-like molecular interaction

behavior in the liquid.

Diffusivities will be determined from temporal records of evolving concentration profiles through multi-detector

measurements of radioactive tracer emission. An initially solid, cylindrical sample contains a radioactive isotope at

one end. After melting, radiation escaping through small bores in an isothermal liner/radiation shield is monitored

via a chain of detectors. Data evaluation is facilitated by a novel algorithm, which is not limited to the simple

initial conditions traditionally used in diffusivity studies. The algorithm permits data deduction ti-om any sequence

of concentration distributions. Hence, diffusivity data can be gathered over a range of temperatures in a single

experiment. Utilizing the different radiation absorption behavior of different photon energies, we will investigate

the significance of the "wall" effect. This effect is currently believed to contaminate diffusion studies in narrow

capillaries used to suppress convection at normal gravity.

TASK SIGNIFICANCE:

The diffusion of species in melts and its temperature dependence is important for the product quality in numerous

metallurgical and semiconductor manufacturing processes. Hence, a detailed understanding of diffusion in liquid

metals and alloys is essential for an efficient improvement of numerous technological processes. However, the

accurate measurement of diffusivities in liquids is hampered by difficult-to-control transport contributions from

convection. At this point, due to the complex structure of liquids, our theoretical understanding of diffusion in

liquids is limited. Theoretical models of diffusion in liquids abound. Yet, a verification of these models requires

more accurate diffusivity data for wider temperature ranges than are currently available. This investigation will

provide accurate data tot selected materials and, hence, will further both process development as well as fundamental

science.
PROGRESSDURINGFY 1994:

A novel algorithm was developed for the evaluation of diffusive concentration profiles without use of boundary

conditions and specialized initial conditions.

A conceptual design was completed based on detailed sensitivity and dimensional analyses of the optimal diffusion

capillary and collimator geometry considering experiment time, spatial resolution and diffusivity data precision,

detector sensitivity and minimization of the radioactive dose, isotope half-life and collimator/radiation shield

absorption characteristics.

An isothermal diffusion oven with minimal power consumption1 adequate radioactive shielding and permitting ready

sample exchange, was designed and built.

A boron nitride coated graphite heater cartridge was selected for its uniform radioactive absorption characteristics and

tested under oxidizing conditions over the temperature range to be used in the experiments.

Following extensive testing of various detectors for energy resolution at the elevated operation temperatures to be

expected in a flight experiment, CdZnTe detectors were chosen and integrated with miniturized data acquisition

electronics.

The development of software/or data acquisition and evaluation was started.

Sample preparation and ampoule filling procedures were tested with particular concern for obtaining non-wetting

conditions between the metal and ampoule material.

A design verification and sensitivity testing procedure for the whole experimental setup was developed utilizing a

solid, radioactive sample to be mechanically moved along the diffusion direction in liquid samples.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS StudenLs: 0

PhD Students: 1

TASKINITIATION: 2/93 EXPIRATION: 8/94

PROJECTIDENTIFICATION:963-25-08-10

NASA CONTnACTNO,NAS8-39718

RESPONSIBLECENTER: MSFC

11-146
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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Double Diffusive Convection during Growth of Lead Bromide Crystals

PRINCIPALINVESTIGATOR: Dr. N. B. Singh Westinghouse Electric Corporation

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The main objective of this program is to evaluate, understand and eliminate thermosolutal convection during the

crystal growth of PbBr:-AgBr systems. The program will provide a quantitative understanding of convective effects

and a correlation of experimental data with theories developed for thermosolutal convection will be earned out. For

the PbBrz-AgBr system less dense solute causes the convective (thermosolutal) instability in addition to

morphological instability. Also, this system is optically transparent and we can monitor the interface shape to

study the convective and morphological instabilities. The technical objectives of this program are to define the

parameter at normal gravity to minimize the thermosolutal convection during growth of doped lead bromide crystals

to achieve homogeneous distribution of dopant, significantly reduce the optical and acoustic scattering caused by

convection during lead bromide crystal growth, and produce lead bromide crystals with unparalleled optical

homogeneity for advanced device applications. This will be achieved by experimentally verified stability diagrams

and direct observations on solid-liquid interlace during crystal growth.

TASK DESCRIPTION:

To achieve these objectives, cryst_d growth experiments will be conducted on earth and in space. Measurements

involving Rayleigh number as a function of aspect ratio, and the radius of the growth tube to the length of the melt

column, will be made. Experimental results will be compared with the stability, diagram to test the validity of

morphological and convective stability theories.

TASK SIGNIFICANCE:

The scientific objectives of this program are to understand the thermosolutal convection during the crystal growth of

PbBr2-AgBr system. This will be achieved by growing live crystals at five different concentrations, which will lead

Io different solutal convective levels. The experimental values of the concentration distribution will be compared

with the theories based on pure diffusional growth to evaluate the effect of convection. Also, numerical studies will

be carried out to study the convective and morphological instabilities, and to determine the critical concm_tration of

dopant for a particular growth velocity and gravity level. Theoretical instability diagrams will be compared with the

experimental studies. Relevant analytical characterization techniques are to be used m evaluate the effect of

convection on crystal quality. These studies will provide basic data on convective behavior in doped lead bromide

crystals grown by the commercially imlmrtant Bridgman process.

PROGRESSDURING FY 1994:

Minutes of the March 1992 Flight Science Readiness Review have been published. Dr. Singh is taking action

based on the recommendations of the review.

To study the effect of thermal convection, tour lead bromide crystals were grown at different thermal Rayleigh

numbers. X-ray rocking curves, X-ray contour scans and chemic',d etchpit studies showed that cry'stal quality

decreased with increasing thennal Rayleigh number. The crystal grown at lowest thermal Rayleigh number showed

highest quality and the crystal grown at highest thermal Rayleigh number showed the worst quality.

Lead bromide-silver bromide cryst',,ds were grown in a Bridgman tumace at a thermal gradient of 21 K/cm and pull

rate of 2.3 x 10-_cm/s. The measured concenU'ation of silver did not match with the values predicted by theories

based on pure diffusive or convective transport. X-ray rocking curves and contour scans for d)10) plane showed that

II-147
crystal grown at lower dopant concentration had better quality. The crystals grown at lower solutal Rayleigh

number exhibited small variation of lattice parameters and better homogeneity in dopant distribution. Results of

etchpit studies also supported these results.

We have carried out a crystal growth run at a temperature gradient of 20 K/cm, to test the validity of stability

theory. We are using a charge containing 5000 ppm silver bromide. When we have steady-state conditions, the

interface is flat. When we start pulling the growth tube, up to the pull rate of 0.23 micrometer per second, we did

not observe any significant change in the shape. At the pull rate of 0.29 or higher, we observed that the interlace

turns concave, followed by a depression in the middle. We observed very interesting phenomena with the increasing

time. We observed that the shape of the intertace is changed significantly and can be explained on the ba._is of

toroidal flow, just as theory had predicted. A cellular or dendritic microstructure later developed within this

depressed interlace region. When we stopped the pulling of the growth tube, the inter/hce recovered its original flat

shape. We did not observe this phenomena in the pure lead bromide system and identical crystal growth conditions.

We are excited to have experimentally conlirmed the predicted region of the interface instability under convective

growth conditions. This type of instability can be explained on the basis of toroidal fluid flow. This type of flow

will not occur in the pure system and the pressed pit at the interface occurs under the point where the flow field

converges. These results are further justification tbr studying this system in low gravity. We are planning to start

next run containing 500 ppm and we hope to increase the growth velocity 10 times to observe the instability.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/93 EXPIRATION: 9/94

PROJECT IDENTIFICATION: 962-24-05-01

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Singh, N.B.. Stewart, A.M.. Hamacher. R.D.. Mazelsky, R., Duval, W.M.B.. Santoro. G.J., DeWitt. R. and Lehoczky, S.L.

Convecto-diffusive growth of lead bromide crystals: a test of theories. J. Cryst. Growth. 139, 158-164 (1994)

II IIllll11111111111111 Illllllllllllallllllllllllllgllllll1111111a! III11!111!1 _III|_I_IllI_|II|_I|11I111|_|I!1111|_!_I_lIe_I_II!I|_||IIIIII_|_|_IIll_II11_III_III_II_III1111I_I_|_I11I11IIIIII_ IllllIIIIIIIIIIlllilllll!llllllOll!lll Ilollllllllll

I1-148
Particle Engulfment and Pushinjz by Solidifying Interfaces

PRINCIPALINVESTIGATOR:Prof. Doru M. Stet.anescu University of Alabama, Tuscaloosa

CO-INVESTIGATORS:

P. Curreri NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The primary objective of this task is to further develop the existing understanding on pushing and engulfment of

particles by planar liquid/solid interfaces during solidification of metallic alloys.

The approach towards achieving this objective is by developing an analytical and then a numerical model describing

this phenomenon, with a parallel experimental validation effort. The ntnnerical model is required in order to include

the effect of convection in the liquid on interface morphology and the particle/interface interaction. The interaction

between an insoluble ceramic particle and a liquid-solid interl.ace during solidification is significantly influenced by

gravitational acceleration. Since the interaction between an insoluble ceramic particle and a liquid-solid inter/ace

during solidification is significantly influenced by gravitational acceleration, microgravity expermaents will be

perlormed to validate these models and to further contribute Io the experimental data base for metals/ceramic

particulate mixtures.

TASK DESCRIPTION:

To acquire further insight in the physics of particle behavior, directional solidification expertments with transparent

organic materials doped with polystyrene particles were scheduled. It was planned to use results from these

experiments to validate the analytical model developed so far.

Ground based expertments under controlled solidification conditions with AI-SiC systems to document

pushing/engulfment phenomena in metallic systems were also scheduled. In addition several tasks required in the

flight requirements definition effort were to be per/'ormed.

TASK SIGNIFICANCE:

It is of fundamental and practical importance to understand and control parUcle behavior at the solid-liquid interface

during solidification. Particle behavior determines the unitormity of their distribution m the matrix. Unitormity of

particle distribution is of great significance as it dictates the mechanical and physical properties of the composites.

Introduction of insoluble ceramic particles in a metal matrix primarily involves three stages: transter of particles

from gas to liquid, interaction of particles in the liquid state and finally transfer of particles from liquid to solid. It

is the last stage that is the most important and yet the least understood since it is the outcome of the interaction of

numerous solidificalaon variables. The anticipated results from this research program will provide a much better

understanding of this stage of metal matrix composite processing and therein lies its significance.

PROGRESSDURINGFY 1994:

Modeling:

Through a combined thermal and lbrce field calculation a model has been developed to predict particle behavior at the

interface. The derived equations predict the tormation of bumps or troughs on the melt interface behind the

particles. This was confirmed by experiments on transparent systems containing SiC, polystyrene, or gas bubbles.

The model allows calculation of the critical velocity Ibr particle engulfment:

V =A(G/Co) j/2 R"_

where, C,, is the equilibrium solute concentration, G is the thermal gradient 'ahead of the interlace, R is the radius of

!1-149
curvature, and A is a constant that includes materi_l parameters. Experimental and analytical modeling work on

transparent systems have demonstrated that in the presence of convective fluid flow the critical velocity for particle

engulfment increases. This is primarily due to particles moving away from the interlace with a velocity comparable

to the fluid flow velocity.

Progress in ExperLmental Work:

Transparent organic materials doped with polystyrene particles have been directionaUy solidified. In-situ behavior of

these particles was observed under variable solidification conditions. Results from these experiments were used to

validate the analytical model developed so far, A better understanding of the role of interface morphology, e.g.,

planar or columnar, was also achieved.

Metallic systems are opaque to light microscopy. Determining the position of the particles before and alter

directional solidification is important to accurately determine the critical velocity for particle engulfment. Thus it

w&s necessary to evaluate several non destructive methods. Samples have been sent out to three different

organizations (Panametrics, Boeing, and Argonne National Laboratory) lor initial evaluation.

Water spray quenching experiments in the directional solidification furnace have been perlbrmed on both alumina

and graphite crucibles and the corresponding cooling rates have been determined. This work was necessary for the

definition of flight requirements.

A cartridge design and a method to labncate flight samples incorporating three thermocouple tips to monitor thermal

profile during the experiments has been developed. These samples will be tested at CNES.

The critical velocity for maintaining a planar interlace in 99.999% AI has been determined to be 60 gm/s.

Since spherical SiC particles required for the experiments were not available, a sputtering technique was used to coat

spherical Ni particles with SiC. Spherical particles processed in this way have been characterized for coating

unilormity and thickness.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 1

TASKINITIATION: 2/93 EXPIRATION: 2/96

PROJECTIDENTIFICATION:963-25-08-11

NASA CONTRACTNO.NAS8-38715

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Ahuja, S., Stefanescu, D.M., and Dhindaw, B.K. "Role of processing/system parameters on the interaction between

liquid/solid interfaces and insoluble particles." Cast Metal Matrix Composites, Proceedings of the 2nd International

Conference, D.M. Stefanescu and S. Sen. eds.. AFS. Des Plaines, IL. 44-56 (1993).

Pang, H.T.. Stefanescu, D.M., and Dhindaw, B.K. "Influence of interface morphology on the pushing/engulfment

transition of polystyrene particles in succinonitrile + water matrices." Cast Metal Matrix Composites, Proceedings of the

2nd International Conference. D.M. Stefanescu and S. Sen, eds., AFX, Des Plaines, IL, 57-69 (1993).

Books

Pang, H., and Stefanescu, D.M. "'Influence of Interface Morphology on the Pushing/Engulment Transition of Polystyrene

Particles in Succinonitrile + Water Systems" in "Experimental Methods for Microgravity Materials Science Research."

Edited by: R.A. Schiffman and B. Andrews TMS/Warrendale, PA, pp 209-213, 1994.
Crystal Growth of ZnSe and Related Ternary Compound Semiconductors by Physical Vapor Transport

PRINCIPALINVESTIGATOR: Dr. Ching-Hua Su NASA Marsh'dl Space Flight Center (MSFC)

CO-INVESTIGATORS:

R. Brebrick

M. Volz

Y, Sha

D. Noever

S. Sanghanitra

S. Johnson

Marquette University

NASA Marsh'aft Space Flight Center (MSFC)

Universities Space Research Association CUSRA)

NASA Marsh'all Space Flight Center (MSFC)

Santa Barbara Research Center

Santa Barbara Research Center

TASK OBJECTIVE:

The investigation consists of extensive ground-based experimental and theoretical research efforts and concurrent

/light expertmentation. The objectives of the ground-based studies are to obtmn the experimental data and conduct

the analyses required to define the optimum growth parameters for the flight experiments, perfect various

characterization techniques to establish the standard procedure for material characterization and quantitatively

establish the characteristics of the crystals grown on Earth as a basis for subsequent comparative evaluations of the

crystals grown in a low-gravity environment, and develop theoretical and analytical methods required for such

evaluations.

TASK DESCRIPTION:

The crystal growth experiment will use a novel vapor transport three-thermal-zone heater translating method. The

Crystal Growth Furnace (CGF) or Advanced Automated Directional Solidification Furnace (AADSF) will be ideal

for this experiment because they provide two high-temperature end zones and a booster heater at the center of the

furnace with translation capability. Using this technique, large single crystals of CdS, CdTe, PbSe, and ZnTe have

been grown successfully in this laboratory.

TASK SIGNIFICANCE:

The materials to be investigated are ZnSe and related ternary semiconducting alloys, e.g., ZnS_ Se_._, ZnSeI._Te,,

and Zn_._Cd_Se. These materials are useful for opto-electronic applications such as high efficient light emitting

diodes and low power threshold and high temperature lasers in the blue-green region of the visible spectrum. The

recent demonstration of its optical bistable properties also makes ZnSe a possible candidate material tbr digital

optical computers. Compositional non-uniformity, microstructural crystal defects (e.g., dislocations, small-angle

grain boundaries, and second phase precipitates), and deviation from stoichiometry can seriously limit

state-of-the-art device pertbrmance and future device applications. The reduction of gravity-driven convective fluid

flows in a low-gravity environment is expected to be advantageous in minimizing these compositional variations

and structural defects.

PROGRESSDURINGFY 1994:

1. Fundamental of transport theory was confirmed by simultaneous measurements of partial pressures and transport

rate.

2. Growth parameters tor horizontal unseeded growth of ZnSe were optimized.

3. Characterization methods to assess the effect of gravity on the grown crystals were established.

11-151
STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASKINITIATION: 2/93 EXPIRATION: 2/96

PROJECTIDENTIFICATION:963-21-08-09

NASA CONTnACTNO.NASS-39718

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Biao, Y., Azoulay, M., George, M.A.. Burger, A.. Collins. W.E., Silberman, E.. Su. C.H., Volz, M.P., Szofran, F.R. and

Gillies. D.C. Photoluminescence of vapor and solution grown ZnTe single crystals. J. Cryst. Growth. vol. 138. 219-224

(1994).

Sha, Y.G. Su, C.H., and Szofran, F.R. Thermodynamic analysis and mass flux of the HgZnTe-Hgl_ chemical vapor

transport system. J. Cryst. Growth. vol. 131, 574-588 (1993).

Su. CH., Volz. M.P., Gillies. D.C., Szofran. F.R.. Lehoczky. S.L.. Dudley. M.. Yao. GD.. and Zhou, W. Growth of ZnTe

by physical vapor transport and traveling heater method. J. Cryst. Growth. w_l. 128. 627-632 (1993).

Proceedings

Su, C.H., Sha, Y.G., Volz, M.P., Gillies, D.C., Lehoczky, S.L., Zhou, W., Dudley, M., Liu, H.C., Brebrick, R.F., and

Wang, J.C. "Ground based research on the growth of I]-VI compound semiconductors by physical vapor transport."

Proceedings of the 8th Annual Symposium on Microgravity Science and Space Processing, AIAA 32nd Aerospace Sciences

Meeting, paper no. 94-0564 (1994).

Zhou, W., Wu, J., Dudley. M., Su, C.H.. Volz, M.P., Gillies, D.C., Szofran, F.R., and Lehoczky, S.L. "Characterization of

growth defects in ZnTe single crystals." Materials Research Society Proceedings, Infrared Detectors - Materials.

Processing, and Devices, A. Applebaum and L.R. Dawson. eds., 299 (1993).

Presentations

Chen, K.T., George, M.A., Zhang, Y., Burger, A.. Su, C.H., Sha, Y.G., Gillies. D.C., and Lehoczky, S.L. "Selenium

precipitation in ZnTe crystals grown by the physical vapor transport." American Physical Society Meeting March,

Pittsburg, PA, March 21-25. 1994.

Ruggeri, R.T., Shepherd, W.B., Bowman, D.R., Bohnhoff-Hlavacek, G., Willenberg, H.. Su. C.H., Szofran, FR., Rubart,

W.S., and Stoebe, T.G. "The crystals by vapor transport experiment (CVTE): space processing and preliminary results."

44th International Astronautic Congress of the International Astronautic Federation, Graz. Austria. October 16-22, 1993.

Sha, Y.G., Su, C.H., Palosz, W., Volz, M.P., Gillies, D.C., Szofran, F.R., Lehoczky. S.L.. Liu, H.C., and Brebrick, R.F.

"Mass flux and crystal growth of ZnSe by PVT." 8th International Conference on Vapour Growth and Epitaxy dCVGE-8).

Freiburg, Germany, July 24-29. 1994.

Su. C.H., Sha, Y.G., Volz, M.P., Gillies, D.C., Szofran, F.R., Lehoczky, S.L., Zhou, W.. Dudley, M., Liu, H.C.. Brebrick,

R.F., and Wang, J.C. "Ground based research on the growth of II-VI semiconductors by physical vapor transport." AIAA

32nd Aerospace Sciences Meeting, 8th Annual Symposium on Microgravity Science and Space Processing, Reno, NV,

Janaury 10-13, 1994.
|I. MSAD Program Tasks h Flight Research Discipline: Materials Science

Measurement of Viscosity and Surface Tension of Undercooled Melts

PRINCIPAL INVESTIGATOR:Dr. Julian Szekely Massachusetts Institute of Technology (MIT)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this investigation is to utilize the electromagnetic levitation unit, TEMPUS, on IML-2 to measure

the viscosity and surface tension of undercooled metallic melts. To date, little study has been made of the

thermophysical properties of undercooled melts, and a controversy exists over whether the temperature dependence of

the viscosity obeys an Arrhenium-type or a power-law relationship.

TASK DESCRIPTION:

In this investigation, a "squeezing" force will be applied to a suitably-positioned sample to induce oscillations. The

rate of decay of the amplitude of these oscillations will be observed in order to measure the viscosity at a number of

temperatures in the undercooled regime, while the frequencies of the oscillation modes will be used to deduce the

surface tension at these temperatures.

Our ettbrt consists largely of a comprehensive program of mathematical modeling designed to give a detailed

understanding of what can be expected from the flight experiment. To date, the main thrust of the modeling work

has been to develop the methodology and to perform calculations predicting the behavior of

levitation-melted/electromagnetically-positioned metallic droplets under both Earthbound and microgravity

conditions.

TASK SIGNIFICANCE:

The main purpose of the work was to be able to predict the electromagnetic threes and heating rates,

electromagnetically-driven velocity fields within the sample, the transient behavior of the system, and the

deformation of the sample. The accuracy of the computational models has been checked by comparison with

available analytical results and the results of ground-based experiments.

PROGRESSDURING FY 1994:

During the IML-2 mission this experiment was performed in the TEMPUS facility. The surface tension and

viscosity of undercolled metallic melts - including both pure metals (Cu, Au, and Ni) and alloys (AuCu) - were

measured. The oscillating drop technique with electromagnetic levitation was used to measure the thermophysical

properties in a containerless fashion. By this method, a metallic sample was positioned, melted, and squeezed by

high-frequency electromagnetic fields in TEMPUS. Once the sample is molten, it is squeezed and deformed by a

brief current about its equilibrium free surface shape. The surface tension can be related to the frequency of the

oscillations, and the viscosity can be derived from the rate at which the oscillations are "damped. The experiments

were pertbrmed in microgravity in order to eliminate the strong electromagnetic lorces that are required to levitate

metallic samples on Earth. These strong forces drive turbulent flow inside the sample, making it impossible to

measure viscosity and deforming the sample to an extent that makes measurement of the surface tension more

difficult.

For three experiments mentioned above (Au, AuCu, and ZrNi), the digital data contained in the ran-telegram were

analyzed with respect to the heater and positioner control voltages and temperature. The temperature data were

rescaled using the effectives emissivities determined at the melting plateaus, which occurred at know temperatures.

Surface tension values fo Au, AuCu, and ZrNi have been determined, and the results are very promising and

represent the first surface tension data obtained in microgravity.

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ll-153
STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASKINITIATION:12/90 EXPIRATION: 6/95

PROJECTIDENTIFICATION:963-25-08-08

NASA CONTRACTNO.: NAG8-970

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Schwartz. E. and Szekely, J. "S_me perspectives cm electromagnetic levitation in space experiments." Proceedings of

Electromagnetic Processing of Materials. The Iron and Steel Institute of Japan. Nagoya, Japan, 1994.

Schwartz, E. and Szekely, J. "The shape of liquid metal droplets in electromagnetic levitation experiments considering

internal fluid flow." Proceedings of Experimental Methods for Microgravity Materials Science. 1994 TMS Annual

Meeting, San Francisco. CA, 1994. 73-79.

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II-154
Test of Magnetic Damping qf Convective Flows in Microgravity

PRINCIPALINVESTIGATOR: Dr. Frank R. Szotran NASA Marshall Space Fright Center (MSFC)

CO-INVESTIGATORS:

S. D. Cobb

M. B. Robinson

M. P. Volz

S. Motakef

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

Computer Assisted Process Engineering (CAPE)

TASK OBJECTIVE:

The objectives of this study are: to test experimentally the validity of the modeling predictions applicable to the

magnetic damping of convective flows in conductive melts as this applies to the directional solidification of

semiconductor and metallic materials in the reduced gravity levels available in low Earth orbit; and to assess the

effectiveness of magnetic fields in reducing the fluid flows occurring in these materials during space processing that

result li:om density gradient.s (driven by the residual steady-state acceleration or g-jitter) or surface tension gradients

(Marangoni flow). To achieve these fundamental objectives, the following specific objectives will be pursued:

• To determine the relative effectiveness of transverse and axial magnetic fields in suppressing convective flows in

lg driven by gravity, vibration, or surface tension gradients;

• To test the validity of magnetohydrodynamic modeling predictions in characterizing the effectiveness of an axial

magnetic field tot suppressing convective flows in 1g.

TASK DESCRIPTION:

To achieve the objectives of this investigation, we will carry out a comprehensive ground-based program using a

carefully chosen set of materials. Some of these materials have been intensely studied in environments that have

not stmultaneously included both low gravity and an applied magnetic field. These include a dilute 'alloy (Ca-doped

Ge) in which solutal effects will be negligible and three solid solutions--Ge-Si, lnSb-GaSb, and Cu-Ni--with

liquid density ratios of 2.18, 1.07, and 1.012, respectively. Thus, during Bridgman-Stockbarger solidification with

the solid on the bottom, Ge-Si has a strongly stabilizing solutal density variation, InGaSb is very mildly

stabilizing with previous results showing substantial mixing, and Cu-Ni is even less stabilizing. All four systems

will be processed by the Bridgman method using two diameters. In addition, the Ca-doped Ge and Ge-Si systems

will be float-zoned to study the effects of magnetic suppression of Marangoni convection.

TASK SIGNIFICANCE:

During direcOonal solidification of semiconductors, generation of destabilizing temperature gradients in the melt is

unavoidable, resulting in buoyancy-induced convective mixing of the liquid phase. On Earth this convective

mixing is generally very intensive and interferes with segregation of melt constituents at the growth front leading to

less than optimum quality cry.stats. Crystal growth in space provides the opportunity to reduce the convective

intensity and, for some classes of systems and charge sizes, achieve ma.ss transfer diffusion-controlled growth.

Magnetic damping of convection in electrically-conductive melts, however, can be used to provide a higher degree of

control on convection in the melt. Thus our understanding of convective influences can be further advanced, and our

ability to interpret space experimental results may be significantly improved.

PROGRESSDURING FY 1994:

During FY94 a new thermal control system was installed to provide excellent temperature control at all fields up to

5 T and samples of Ge:Ga, InGaSb, and GeSi were grown and analyzed. Emphasis was on the Ge:Ga system.

ll-155
II. MSAD Program Tasks -- Flight Research Discipline: Materials Science

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The initial therm',d control system used time proportioning and ac current and, while adequate lot zero field work,

was not satisfactory for use in high magnetic fields. The current system uses dc current that is slowly vaned but

not turned off and on to achieve temperature control. Temperature control of better than _+0.5 °C at _1 fields is

routine.

The significant accomplishments of the project include:

• Demonstrated mechanical interface demarcation in Ge:Ga at fields up to 5 T;

• Reproducibly observed diffusion limited growth at 5 T in Ge:Ga;

• Developed a furnace-specific model for Ge:Ga growth which correctly predicted the field needed to achieve

diffusion-controlled growth;

• Demonstrated the growth of single-crystal Ge:Ga at 5 T;

• Observed major difference in growth characteristics in Ge0.95Si0.05 between 0 and 5 T;

• Observed significant departure from complete mixing behavior in Ino 2Gao 8Sb

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/92 EXPIRATION: 10/95

PROJECT IDENTIFICATION: 963-21-08-10

NASA CONTRACTNO.: In-house

RESPONSIBLECENTER: MSFC

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II. MSADProgramTasks-- [:light Research Discipline: Materials Science

Vapor Growth of Alloy-Type Semiconductor Crystals

PRINCIPALINVESTIGATOR:Dr. Heriben Wiedemeier Rensselaer Polytechnic Institute

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objectives of this research are: the establishment of experimental trends for the relation between conveclive

flow, mass flux, and crystal morphology; and the identification of microgravity effects and trysted properties for the

ternary semiconductor mercury, cadmium telluride (HgCdTe).

For this purpose, thin epitaxial layers of Hg,._Cd_Te will be grown on (100)CdTe substrates during the USML-2

mission to observe the effects of microgravity on the morphology of the substrate-layer interface and of die

epitaxial layer.

TASK DESCRIPTION:

This experiment requires the hot zone to be 625 °C and the cold zone to be 455 cc. The total duration of the

experiment is 16 hours. The ampoule assembly is designed to be 160 mm in length, 18 mm outer di:uneter, and

about 31 grams total weight. A cadmium telluride single crystal and a sapphire disc are used for the epitaxi_d

crystal growth as substrate and substrate support, respectively. Four ttme intervals are required for cry sud growth,

namely, heat-up, annealing, growth, and cool-down periods.

Identical expertments, except for the level of gravity, are performed on ground and in space to provide a direct

comparison of results.

TASK SIGNIFICANCE:

The lateral and axial compositional homogeneity (distribution) of the major and dopant components is expected to

be more uniform for the space-grown epitaxial layers. The density of dislocations, of strain-induced defects, and

possibly the number of inclusions are expected to be considerably reduced relative to ground-control specinlens.

In addition, observations of the effects of reduced gravity on the lbrmation of defects at the growth interface and on

the propagation of these "birth detects" into the layer are of basic scientific and technological significance.

PROGRESSDURING FY 1994:

On-going ground-based experiments in the P.l.'s laboratory and in the GCEL furnace revealed the elIccts of growth

temperature on the critical transient time of layer growth. These experiments provide the basis for the definition and

retinement of flight experiment parameters.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 1

Phi) Students: 3

TASK INITIATION: 10/90 EXPIRATION: 10/96

PROJECT IDENTIFICATION: 963-2l-0g-()3

NASA CONTRACT NO.NAS8-39723

RESPONSIBLE CENTER: MSFC

_I_¢_*_B_i_*___*_I_I_I_i_eDs_e_I_I_i_e_*_*_*_j_*_*_1*_D_I*_B*_I_*_B_¢_

II-157
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

,Journals

Palosz, W.. and Wiedemeier. H. Residual gas pressures in sealed fused silica glass ampoules. J. Cryst. Growth, w_l. 131.

193 (1993).

Wiedemeier, H.. and Wu. GH. Fast vapor growth of cadmium telluride single crystals. J. Electronic Materials. vol. 22,

1121 (1993).

Wiedemeier, H., and Wu. G.H. Fast growth of Cd_.xZnxTe single crystals by physical vapor transport. J. Electronic

Materials. vol. 22, 1369 (1993).

Presentations

Wiedemeier, H. "Vapor growth of Hg_.,Cd_Te epitaxial layers on ( 100)CdTe substrates under normal and reduced gravity

conditions." 8th International Conference on Vapor Growth and Epitaxy, Stuttgart, Germany.

Wiedemeier, H. "Vapor growth of Hg,,Cd,Te epitaxial layers on (100)CdTe substrates under normal and reduced gravity

conditions." Max-Planck-Institute, Stuttgart, Germany.

Wiedemeier, H. "Vapor growth of Hg_ ,Cd,Te epitaxial layers on 1100)CdTe substrates under normal and reduced gravity

conditions." Solid State Research Symposium, University of Munster. Munster. Germany.

II-1 5 8
Superfluid Transition of 4He in the Presence of a Heat Current

PRINCIPALINVESTIGATOR:Prot. Guenter Ahlers University of California, Santa Barbara

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this project is to study the superfluid transition in a heat current. One issue which we are

addressing is whether the superfluid transition remains continuous in the presence of a heat current. A second

objective is to make measurements of the effective conductivity of the system very close to but slightly above the

transition temperature T_as a function of the current.

TASK DESCRIPTION:

Theoretical work by Onuki has predicted that the transition will be hysteretic. We are looking for this hysteresis in

a finite current. Onuki's theory does not take the effect of gravity into consideration, and it is not clear to what

extent the gravitationally induced inhomogenity will hide the predicted effect. Recent calculations by Haussmann

and Dohm have indicated that a nonlinear range of parameter space should be accessible where the conductivity will

depend upon the current. This range will be exceedingly close to T_. where the ultra-high resolution thermometry

developed previously in our laboratory will be essential, and where gravity effects will play an important role.

TASK SIGNIFICANCE:

We expect that our earth-bound measurements will yield information about possible advantages to be gained from

micro-gravity experiments. We will have to determine whether gravity effects completely obscure the nonlinear

regime, thus necessitating microgravity experiments in order to make these nonlinear effects observable, or whether

useful information can be obtained in an earth-bound laboratory.

PROGRESSDURING FY1994:

Since January 1, 1994 we have continued to study the finite heat current effect on the thermal conductivity of'He

near the lambda transition. The following progress has been made:

We finished developing a computer code to calculate the two-dimensional temperature field in our cell. The

simulation gave results in agreement with known experimental results and enhanced our understanding of our

experimental data, particularly in the HeI--Hell coexistence region. Furthermore, it indicates that the side wall of our

cell has a negligible effect in studying the nonlinear thermal conductivity of _He.

To analyze the experimental data we obtained last year, we have developed a computer code to do nonlinear least

squares fitting of our experimental data. This is nontrivial due to the complexity of the model which involves a

number of numerical procedures. With this program we have performed extensive data analysis using different trial

models of conductivity.

Quantitative comparison of our data with the theoretical prediction by Haussmann and Dohm requires the numerical

evaluation of the Haussmann and Dohm formulas. With generous support from Dr. Haussmann and Professor

Dohm we have developed a computer program to evaluate the theoretical predictions for the thermal conductivity of

4He as a function of heat current and distance from T_. This enabled us to make quantitative comparison between our

experimental data and the Haussmann and Dohm theory. We shared our code with Dr. Rob Duncan's group at

Sandia National Lab, since it is equally important to their NASA sponsored research.

lIIIIIIIIIIII IIIIIeIIIIIIIIIIIIIIlIIIIIIIIIIIIlIIIIIIIIIiiiIlIIIIIIIIIIIIiiIIliIIIIlIiIIIIiiI IIIIIIIIIIII IIIIIIIIIIII!IIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIo IIIIIlIIllIIiI IIIIlI!iiIiIIIIIIiiiIIIIIII!II!iaIIIIIIoIIlIIIiiIIIIIII!III IIIIIIIIlIIiiiII II

1I-159
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

i _ i a i | |o | o Ii na | o I a | I a o I I o o o o o Ig o II o t o o I a o Io o Iu o I n o n a o I a o n ao o io o o a o Ill o I u I I o ou a o I i u J n I _ _ a J _ a Jo tI o I a o o I lu a I o ao 1 t o | ! ! o I g o I uo n no o a o I a o I I | o oo o I o o ! I o 01 o |u i | a| o a o o I a o I a o I as | a | o o J | I a o n a o | a a n i uo o uln u o n a | n u in a o ma o o a o o _ ! o Ig 8 n a o nai i mi io | i o | i o | o o | ea | o | | _ a o i

Our initial data analysis indicated that t'urther experimental data with ceils of different thicknesses are needed. We

constructed an experimental cell with 0.4mm thickness, as compared to 1.lmm in the previous experiment. This

cell was installed in our apparatus, cooled down, and used to take data. The analysis of this second set of results m

now well under way. A third cell, of thickness 0.8 nun, will also be used in the near future.

Finally, a detailed written report was completed and submitted to JPL following the January 1994 NASA workshop

in W_higton DC where we (Professor Guenter Ahlers and Dr. Feng-Chuan Liu)

each presented an oral report.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-07-17

RESPONSIBLECENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Ahlers. G. "Dynamics of the superfluid transition of 4He." Proceedings of the NASA/JPL 1994 Microgravity Low

Temperature Physics Workshop,

Liu, F.C., and Ahlers, G. "The effect of a finite heat current on the lambda-transition and on the thermal conductivity of

4He." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

! | I | | |eellH nee e | e eel |11 e I! o el ell II $ o el| | | lee el e !e e ! | | I e | el e ee ! | e i i I! ! e e ! e e ! e| I | | e ! e | ! i ! ! e I ie ! ! I e ! | | ! | | 0 | I Ie ! e e ee e e e ! H !! | ! ! e I e e ! II ! le I ! e ! I e ! e i ! ee ! e ! e e o I | ! e e !e e el e ! e i ! e ! | ! ! |i i | ! e ! I e ! e ! ! e | i n !I e | I | I 0 | i 01 !e i ! e n01 ! e 0 ! e ! ! e! ! e e e ! ! e I! I | i | o | e e ! | Ie I i e ! !

II-160
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

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Microgravity Test of Universalitv and Scaling Predicticms Near the 3He Critical Point

PRINCIPALINVESTIGATOR: Dr. Martin B. Barma[z Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

U.E. Israelsson

J. Rudnick

Jet Propulsion Laboratory (JPL)

University ot California. Los Angeles

TASK OBJECTIVE:

The objective of this task is to test the universality and scaling laws at the liquid-gas critical point of 3He in a

microgravity environment. The task objectives will include 1) precision measurements of the isothermal

compressibility along the critical isochore to determine the critical exponent g and 2) precision measurements of the

constant volume specific heat along the critical isochore to determine the critical exponent a.

TASK DESCRIPTION:

Theories describing the behavior of thermophysical properties near critical poink_ were developed using the concept

of scaling laws. These models led to the definition of universality classes where critical points of the s_une class are

predicted to have the same critical exponents. Efforts to validate the scaling law predictions near a liquid-gas critical

point in ground-based laboratories are limited due to the gravity induced vertical density gradient associated with the

divergence of the isothermal compressibility. This density gradient becomes appreciable as the critical lx_int is

approached leading to a significant smearing of the transition. Calculations have shown that in a microgravity

environment (10 .6 g) accurate specific heat and isothermal compressibility measurements could be obtained two

orders of magnitude in reduced temperature closer to the critical point. Techniques are being developed for the

simultaneous measurement of both static (specific heat, sound velocity, and compressibility) and dynamic (sound

attenuation and dispersion) properties. These studies will require accurate measurements of pressure (Dp/p ~ 10"_),

density (Dp/p ~ 10"9), and temperature (DTfT ~109). ).

TASK SIGNIFICANCE:

The ability to perform these simultaneous measurements in microgravity should provide a very stringent test of the

universality predictions.

PROGRESSDURING FY 1994:

During FY94, we designed, fabricated, and tested a GdCI_ high resolution thermometer for operation at the He 3

critical point, T_=3.3K. This GdCI_ HRT was shown to have the same sensitivity at the He _ critial point as a CAB

HRT has at the Lambda Point. A new magnetostrictive fluid transfer valve was also demonstrated at liquid helium

temperatures for use at the He 3 critical point.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-24-04-07

RESPONSIBLE CENTER: JPL

II-161
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Barmatz, M., and Hahn. I. "Microgravity test of universality and scaling theory predictions near the liquid-gas critical

point of 3He." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Hahn, I.. and Barmatz. M. "Application of GdCl3 thermomet_ at temperatures near the liquid gas critical point of 3He."

Proceedings of the NASA JPL 1994 Microgravity Low Temperature Physics Workshop.

Rudnick. J., and Barmatz. M. "Effects of random motions on critical point measurements." Proceedings of the NASA/JPL

1994 Microgravity Low Temperature Physics Workshop.

lUO io_ll iu iio iI| iIt * i|u |oloooI II! IlqUnll Io I IOl I I II ouIolI la I i IIi |o I II i _11 u! | Io I UOla ol aIll oil o! i Ol I | Ii i oi i i I ol uIn no IlI i ol i o| I¢| oleo IooIIIlI Ill I I I IO!IItl I II i lu I la Io| Ioo Iol Ioo Ill laI I!I IoI!Ol IIO IoI IIo Ill i Iqllll IIO I OI Ill Ill IIOI laiili lai !t I It oIt O Ilolal ol o

II-162
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

i.ioleelmlHiiiii01ollll,|lll J llllllolllllJlll J oll.llOl.ll|llll,lll.,.l.l.lmilllll,lllltll! mlllllSlllllt nalllJll.lalllllllll.l.llH iollm unl01111111111Miilet i.ile!t .lll ll01111111111111111| .llllno H IIl_lllll.llll_ll.l.t.

Measurement of the Heat Capacity of Superfluid Helium in a Persistent-Current State

PRINCIPALINVESTIGATOR: Dr. Talso C. Chui Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of the task is to detect any changes in the heat capacity of helium as result of supertluid flow very

near the superfluid transition temperature.

TASK DESCRIPTION:

The flow will be created in a toroidal shaped calorimeter in the form of persistent current. The heat capacity is then

measured from below to above the transition, where the persistent current will decay to zero. The heat capacity will

subsequently be remeasured below the transition to detect any difference. If the experiment shows that the heat

capacity is different with superfluid flow, then a space experiment can be designed to map out the heat capacity

curves as a function of temperature and superfluid velocity,

TASK SIGNIFICANCE:

The results will be compared to the dynamic renormalization group theory, which have recently been applied to

calculate the expected results. The theory, which involves three adjustable parameters, is remarkably successful in

explaining the thermal conductivity and the second sound damping near the lambda transition. The proposed

experiment will give a much more stringent test of the theory because this new experimental situation allows the

theory to make precise predictions without any additional adjustable parameters.

PROGRESSDURING FY 1994:

Recently there was new experimental evidence supporting the idea initially proposed by us that in heat flow

experiment near the lambda transition, the first rise in temperature is associated with vortex creating of the type

proposed by Langer and Fisher to explain the intrinsic critical velocity observed by Clow and Reppy in a superfluid

gyroscope. If this interpretation is correct, it would affect the experiment design significantly. First, the real shift

in the lambda transition temperature as predicted by the renormalization group theory (RG) cannot be easily reached.

Second, the region where vortex creation is not important, and the RG prediction can be realized may be at It I < 10'

where t is the reduced temperature. Theretbre in a heat current arrangement, measurement of the heat capacity at It I

> 10"_would probe the effect of vorticities on the heat capacity rather than the effect of RG.

Based on these development, the emphasis of the experiment has shifted to charting the region of experimental

interest where the RG prediction can be realized. And then designing an experiment that would work in this region.

An experimental cell has been fabricated/or this purpose. The apparatus has been in operation for over a year with

high resolution thermometers capable of resolving temperature to 5x10 4_ K/Hz _j2. The germanium resistance

thermometers and the high resolution thermometers are tully interlaced to a computer with real time graphic

software based on LabView G language. The PID temperature controllers are based on software digital control

implemented with Labview. We are current working at integrating the cell and all the software and hardware

together. A first run is planed early next year.

e eloeeoe_leeeelellleel ! i! !i! ! ! i el ! el! e lie iel ill i i ! e I i I Illlllll I |o I | o I I I! e I ! e I I e ! in ! le ! i! i i! i i! iI ! Illl | I | I I OI !l I I ! I I lllll ! I I! I I ! I l! I | I I I(I I I III I ! Ill I I (! I I! !I ! ! | Illllll III Ill ! 111 Ill ! ! I! Illl ! I I ! I I ! I I I II II ! I I ! I I ! I ! I I II ! l! I l! II O| II OII I I I ! I I ! J i! I I !i i i

II-163
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

olalnaoola4, o o1151all;a|_a|tlotlollollo_g| H o_no_olio|aooiaoo;oo;loaii1oo_oi_oolo"_nii_inno_inainuoI_oo_I_a$_oo_lo_unnaoauoo H olullnooaooao|aellooloolaolaou u oaoloola J olaolaoH o Ja|lo|oaolaoHio|aoluo |a|laolaooa||aolaloolnnol.looloolooloo

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 12/92 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-24-04-08

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Chui, T.C.P, Day, P., Hahn, I., Nash, A.E.. Swanson. D.R.. Nissen. J.A., Williamson. P.R., and Lipa. J.A. "High

resolution thermometers for ground and space applications." Proceedings of the 15th International Cryogenic

Engineering Conference. Genova Italy 1994.

Day, P., Chui, T., and Israelsson, U. "Heat capacity of helium under superfluid flow conditions." Proceedings of the

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Tonucci, R.J., Chui, T.C.P., lsraelsson. J.A. and Lipa, J.A.. "Application of nanochannel array for the studies of finite

size effects near a second order phase transition." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature

Physics Workshop.

Yeh, N.C., Strayer, D.M, Chui. T.C.P_ and Lysek. M.J. "Exploring the helium lambda transition using a high-Q

microwave cavity." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

I!-I 6 4
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

u ,t,,.,,,,n.n.n.llt ,,.,,,,;|Hn|_.,J.l,|v,.i.n.n.n,lV,H,H .n.n.l,lv,,,,.I.nnln.l,,,,,,,l,n,ll,,lUl,l.l.n .lll ll.n.lll,,,,n,_,,,,,l,l,n,.i.i.n,l,,,,u,lli,ll,,,l,l.n.n.l.,I.niln.,,, n.,l,,,.n. ,,,,nill,.n.n.n.i

Nonequilibriurn Phenomena Near the Lambda Transition of _He

PRINCIPALINVESTIGATOR: Dr. T_flso C. Chui Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

Dr. Ulf Israelsson Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

The objective of this project is to obtain information on the order-parameter relaxation time in superfluid helium

near the lambda trransition.

TASK DESCRIPTION:

The experiment will measure the heat capacity of superfluid helium near the lambda transition under a pressure

oscillation at variable t_-equency. There will be a small change in the averaged heat capacity when the frequency is

increased above the reciprocal of the order-parameter relaxation time, thus allowing a measurement of the relaxation

time. The proposed technique is well suited for performance in space where close approach to the transition is

possible without the smearing effect of gravity induced inhomogeneity. Since the relaxation time is predicted to

slow down considerable near the transition, geting closer to the transition will avoid problems on earth assiciated

with extremely fast relaxation.

TASK SIGNIFICANCE:

The order-parameter relaxation tune is an tmportant parameter characterizing "alldynamic processes in a phase

transition. Accurate measurement of this quantity will allow a stringent test of the dynamic renormalization group

theory which can be applied to predict the behavior of this quantity with no adjustable parameters.

PROGRESSDURING FY 1994:

Parts have been fabricated for the experimental probe, This probe is a duplication one that is currently in service for

another project. A new post doctoral associate will join the group and begin conducting expertments in March 1995.

Some calculations were perlormed to understand thermodynamics of helium under a sudden pressure quench.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 9/94 EXPIRATION: 8/96

PROJECT IDENTIFICATION: 962-24-04-12

RESPONSIBLECENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Chui. T.C.P. and Israetsson. U.E. "Heat capacity under pressure oscillations- a proposal to measure the order-parameter

relaxation time in space." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

II-1 6 5
lI. MSADProgramTasks-- Ground-based Research Discipline: Benchmark Science

_t;llasulnlnloamllnsla|lln|nao|u0ol! OOlO| .ola.allloololllooaun|ounol.naonnolooloonaol0011olaota0talnoHlaolnonutlaout o ooaoooHIoonao|lnolnolaonaoolooluanoHaonaonaoaa|laoo H oloononlnnllonolgooaolaoH n nloolaonunolnnlnnlaona0oonnnnlloalullno

Determination of the Correlation Length in Helium II in a Microgravity Environment

PRINCIPALINVESTIGATOR:Prof. Russell J. Donnelly University of Oregon

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to measure finite size effects in the isobaric expansion coefficient near the lambda

transition in liquid helium. We will measure the thermal expansion coefficient for liquid helium confined between

parallel plates for a range of temperatures very near the lambda transition temperature (both above and below), a

range of pressures from SVP to about 25 bar, and a range of plate separation distances.

TASK DESCRIPTION:

We will measure the dielec_c constant of helium confined between parallel plates as a function of temperature at

constant pressure. Using the Clausius-Mossotti relation, the density and thus the expansion coefficient of liquid

helium will be calculated. The experimental method involves two measurements (at a given temperature) of the

balancing ratio of an audio-frequency ratio-transformer capacitance bridge, one with the sample capacitor empty and

then one with it filled with liquid helium. Appropriate division of these ratios then yields directly the dielectric

constant at that temperature.

The capacitor used to measure the dielectric constant is a parallel-plate design operated as a three-terminal device in a

1-kHz ratio-transformer bridge, The spacing between the electrodes is determined by a precision shim which can be

easily changed. An identical capacitor is also mounted on the experimental platform and is operated empty as a

reference capacitor. We expect to vary the thickness of the shims between 5 microns and 50 microns.

Initially germanium thermometry will be used for temperature control and measurement. This will allow us to

easily cover a wide range of temperature and to gain familiarity with the experiment. At this stage we will want to

reconcile our results with older, published data. High- resolution measurements will be made alter installing a

paramagnetic salt thermometer identical to that used by John Lipa in his lambda-point heat capacity experiment

(LPE), which successfully flew on STS-52 in October of 1992.

TASK SIGNIFICANCE:

Finite size effects are manifested as a rounding of the divergence in thermodynamic functions near a critical point as

the correlation length increases toward the system size. We can thus test renormalization group theory predictions,

universality assumptions, and boundary conditions.

PROGRESSDURING FY 1994:

The bulk measurements of density and expansion coefficient have been completed and will appear in J. Low Temp.

Phys., vol 98, nos. 1/2, 1995. This work has identified interelectrode stray capacitance as the major source of error

affecting the many experiments measuring dielectric constant of helium, and helps to explain the wide discrepancy

in reported values of the deduced density over the last several decades. We are presently working with Dr. John Lipa

of Stanford University to ascertain the possibility of taking the cryostat to Stanford to be fitted with high

resolution thermometers there and then returned to Oregon for use in measuring density in finite-size gap capacitors

in support of the CHEX experiment. Our experience with the bulk measurements should be invaluable in

eliminating sources of error which would ruin any finite-size experiment.

! I ii nII I I I ill I Ill I I I Ill i nII I ii i II ill Iii i II III I I I ill iiI l ii I I i I nnI II nnI nnnI I I I II I I I I I I I nnnnIi i i I i i. I Ii nini nI I i i I I I ! ini nii i I I i nni I I I I I nnInl i i i ni I I I I I nniI | I I I i ni I II Ii l ii itl i ini in i III I is I II niI I I I Iii nnl I i ni i I in ni 1111 IS I II nI i Itl Iii I II I |ll nii nII I II I II I

11-166
II. MSADProgramTasks-- Ground-based Research Discipline: Benchmark Science

STUDENTSFUNDED UNDER RESEARCH:

BS Degrees: 0

MS Degrees: 0

PhD Degrees: 4

TASK INITIATION: 10/89 EXPIRATION: 9/94

PROJECT IDENTIFICATION: 962-24-04-04

RESPONSIBLECENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Niemela, J.J., and Donnelly, R.J. "Density and dielectric constant measurements in liquid helium." The Proceedinds of the

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

I I Ill II I III III III I lu II I II I I I I I I I I I I I II I I I I I II I I I II I Iu III I II I I I I I, I II I I I I I I I I! II I I I I I I I I I II I I I I I I I I I I II I I I I I I, l II I II I II I I I I I I I II I II. I I I I, I I I I I I I I I I I II II * I I I I I l I I I I II I II I I I I Ill I l II I I I lI I I I I I I 1! I I I II I I l I I I I I I I I I! II I I I I I I ! I, I II I I,, I I I I I I ! I I! II I, I

II-167
Nucleation of Quantized Vortices from Rotating Superfluid Drops

PRINCIPALiNVESTIGATOR:Prof. Russell J. Donnelly University of Oregon

CO-INVESTIGATORS:

.I. Niemela

W-K Rhim

University of Oregon

Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE;

The objective of this research is to study the nucleation of quantized vortices in helium II by investigating the

behavior of rotating droplets of helium II in a reduced gravity environment.

TASK DESCRIPTION;

Two methods well-suited for levitating the helium drop in the near vacuum environment are electrostatic and/or

magnetic levitation. A pure electrostatic scheme requires active feedback control, while a purely magnetic levitation

requires large fields. A hybrid system is probably the best choice. Rotation can be accomplished by coupling to a

charge distribution on the drop surface. We will initially use purely electrostatic levitation for studying drops. The

required charging of the drops can be accomplished by forming the drops around a sharp electrode tip held at a high

voltage. Film flow of helium II can be utilized to create drops at the bottom of a suitable container which can be

filled by a fountain pump and situated above a pair of capictor plates having an appropriate voltage difference

between them.

TASK SIGNIFICANCE;

Nucleation phenomena, m general, are fun "damental to many fields of physics and engineering. In the case of a

rotating superfluid drop it will be possible to produce a state of zero nucleation, analogous to growing a perfect

defect-free crystal. It should also be possible to add a controlled impurity to cause nucleation of a quantized vortez

line in the drop. At low enough temperatures, this will be a pure quantum mechanical tunnelling phenomenon. At

higher temperatures it should be possible to see thermally activated nucleation taking over, for a demonstration of

nucleation under more familiar classical conditions. In conventional systems it is evident that vortex lines come

from some preexisting source, probably vortices trapped by pinning sites on the walls. While this kind of source

of vorticity is undoubtedly important, it is not as fundamental as the "extrinsic nucleation" problem where vortex

line appears when none was present before.

PROGRESSDURING FY 1994:

We have improved the drop forming process to have variable control over the drop rate using a small uniformly

distributed heater on the film flow vessel. The upper limit is dtermined by the smallest perimeter of the vessel

above the free surface of helium contarned in it, which for 1 mm size diameter drops produced from a nominally 1

cm diameter vessel is about 1 drop/s. The use of various tapers at the tip of the film flow vessel enables us to vary

the drop size. We have produced both positive ions (ionized helium atoms) and negative ions (electron bubbles)

using sharp tungsten field ionization or emission tips respectively. The best tips produce negative ions at a

threshold voltage of about 400V and positive ions at a threshold of approximately 1500 V. Currents are in the

range of picoamps for pure ionization or emission, but can increase to microamps by increasing the voltage enough

that a vapor bubble froms around the tungsten tip. The tips are tested in the bath and the presence of ions is

indicated either by observing the current flov_ing from a collector plate to an electrometer or by observing an

"electric fountain" which forms in response to an ion stream. The amount of current measured for pure ionization is

sufficient to charge the drops of 1 nun diameter, and at a rate of 1 drop/s. Very small micron size droplets have

been briefly levitated, but in an uncontrolled manner, by picking up charge from a glow discharge of the tips or an

arcing discharge through the helium vapor. We are currently working on charging single large diameter drops by

pulsing the voltage to the ionization tips to avoid secondary cascading effects in the vapor which "bum out" the

II-168
tips. We have completed a theoretical study of the equlibrium configuration of a single vortex in a freely rotating

superfluid drop (JLTP Vol. 98, Nos 1/2, 1995) and are working on extending these calculations to include

multiple vortices.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-07-12

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Bauer, G., Donnelly, R.J., and Vinen, W.F "Vortex configurations in a freely rotating superfluid drop." Proceedings of the

NASAkJPL 1994 Microgravity Low Temperature Physics Workshop.

Donnelly, RJ. "Superfluid Drops: An Overview." Proceedings of the NASAkJPL 1994 Microgravity Low Temperature

Physics Worksho F.
II. MSAD Program Tasks _ Ground-based Research Discipline: Benchmark Science

nan. I nl I nil I oil so I IIIllOInslimtaoltOllO! Ill lion o$11 OIIOlilli O11 all I 0Into Itoa O01on aooqt oa ode in all nil all1 O|llg Ig iltl1 l aa nalia ooI osoa oo lit I aOolin OI111 IOlll lit OII I I oI all i Olilll II ulnU|H Oi ill illlli|HOOlllltlllO|lllalltOllOllOll|lOlOii|||$|l|Ol|Ol!

Kinetic and Thermodynamic Studies of Melting-Freezing of Helium in Microgravity

PRINCIPALINVESTIGATOR:Prof. Charles Elbaum Brown University

CO-INVESTIGATORS:

J.M. Kosterlitz Brown University

TASK OBJECTIVE:

The objective of this project is to study, experimentally and theoretically, the effects of gravity on the

melting-freezing transitions, including kinetic processes and the equilibrium shape of solids. The research is carried

out on helium, whose unique properties render such investigations possible on a time scale consistent with

experiments in space, under microgravity conditions. Indeed, morphological changes of the solid-liquid interface

(i.e., the "surface" of helium) generally occur tast enough to satisfy the time constraints mentioned above.

TASK DESCRIPTION:

An optical system with special lighting applied to a growth cell contained in a liquid helium dewar allows viewing

of the solid-liquid Interlace (SLI) and of crystal shapes. Rapid image capture equipment allows recording of the

evolution of the SLI and of the crystal shapes in response to changes in temperature and pressure.

TASK SIGNIFICANCE:

These studies are addressing a number of fundamental questions, especially as they relate to the effects of gravity.

These questions include the kinetics of first order phase transitions, the critical behavior in the evolution of crystal

shapes as they approach equilibrium, taceting-roughening phenomena on various surfaces, relative and absolute

values of interfacial tree energy for different crystal laces, and the minimization of a system's free energy subject to

various constraints. Furthermore, many applications should benefit from a deeper understanding of the above

phenomena, among them crystal growth, surface configurations, sintering, and surtace reactivity.

PROGRESSDURING FY 1994:

In our quarterly report submitted in May, 1994, we discussed our observations and some preliminary conclusions on

crystal growth of body-centered cubic (b.c.c.) helium-tour. These studies have continued, with the addition of

nucleation, growth, and morphology of hexagonal close-packed (h.c.p.) crystals of helium-tour.

We have extended these investigations to cover wider ranges of temperature, pressure, and rates of crystal growth.

Our observations on both b.c.c, and h.c.p, helium tour can be summarized as follows.

1. b.c.c, solid helium-four

In the temperature, , and pressure, P, range of existence of the b.c.c, helium-four phase (1.43K < T < 1.76K and

26.1 atm < P < 30.1 ann), this solid behaves, in many respects, like viscous fluid. It should be emphasized that

b.c.c, solid helium is characterized by translational symmetry and long range order typical of ordinary solids, as

demonstrated by x-ray diffraction. Furthermore, the solid supports high frequency elastic shear waves and its

smallest elastic shear modulus, measured at high frequency, is of the same order of magnitude as the longitudinal

modulus. In particular, it is found that b.c.c, crystals formed at the top of a container filled with liquid (supertluid)

helium, deforms under gravity inlo a pseudo-sphericaJ shape. This observation indicates that the solid-liquid

interfaciai tension is essentially isotropic, in agreement with earlier findings. The time constant involved in this

detormation (spherical shape acquisition) is of the order of a few seconds. The mass transport mechanism involved

in this process is now being investigated. Our preliminary conjecture is that quantum mechanical tunneling of

defects (primarily vacancies) is the predominant mechanism. Additional experiments to test this hypothesis are in

progress.

11-170
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

i, i u_ t l 1111, i t 11 ¢ 11 ¢ _l _ I11111 it II II I _ ¢1 t 111 is_ _ I111 as 11_ _11 _ s o_ _s_ 111 s ss s_ I u 11i s s 11 s 11111_ 11so s i11 I11 I11111 I11 I1 _ 11111 _11 _ i1111111111 t l 1111 II 1 III 1 II 1I1 I161 i111tl 1Iii II IIII 1111111 s_11 III 111111 i111111111 III 111111111 i111111 II 1 ii 11ii 1 i i 1 i11 ii _ II

II. The study of h.c.p, helium-tour crystal growth from the normal fluid yields results in sharp contrast to those

round for the b.c.c, case. Indeed, the shapes of h.c.p, crystals and the characteristics of the solid following

solidification are remarkably different. In particular there is no evidence of the solid undergoing any measurable

detormation under gravity, within the observation times avadable; this restricts any possible deformation rates to at

least three orders of magnitude lower values that what is observed in the b.c.c, solid.

Another important factor emerging from the comparison of the behavior of b.c.c, and h.c.p, helium-four during and

immediately following solidification concerns the effects of temperature on the processes under study. As

mentioned above, the solidification of the h.c.p, phase took place from normal fluid, i.e. at higher temperatures than

those of the b.c.c, phase. There is, however, no evidence of mass transport resulting in observable flow and

detbrmation of the solid, while these characteristics are very. prominent in (the lower temperature) b.c.c, phase. This

indicates that the flow processes are not the same in the two phases and that if they are thermally activated, their

activation energies are drastically different. Moreover, since the flow rates appear to be independent of temperature

in the b.c.c, phase (over the limited range investigated), our tentative conclusion is that quantum mechanical

tunneling of vacancies in the predominant mechanism of mass transport in the deformation of b.c.c, helium-four.

The theoretical studies carried out since the last report consist of two parts. The first consists of numerical

simulations of growth of a solid from a liquid in the presence of impurities which tend to concentrate at the

interface. This was modelled by modifying the tree energy F( f, c) by adding a term that is a function of the

conserved impurity concentration,c, and the order parameter f (-1 in the bulk liquid, +1 in the solid). The function

was chosen to make c large at the interface when the gradient of f is large. Simulations were pertbrmed with initial

conditions corresponding to a uniformly undercooled liquid. The results are in accord with our most naive

expectations that this new interface term is just equivalent to reducing the stiffness constant or surface tension at the

interlace so no qualitative differences were observed. The inter/ace became rougher and more convoluted but this is

just a quantitative change and no new and unexpected effects were observed.

Some progress has been made on the problem of dealing with advection of mass from the liquid to the solid and the

density difference between the two phases. Since experiments indicate that the b.c.c, phase of solid 4He allows for

mass flow, the superfluid/b.c.c, solid system can be treated as a binary fluid mixture where the kinematic viscosity

of the superfluid vanishes and is large in the solid. There is also a 10% density difference between the two phases,

so gravity has significant effects. We have constructed a ti'ee energy functional F(r,f ) and dynamical equations

accounting for advection. We are intending to carry out numerical analysis of these equations startmg from initial

conditions for a uniformly undercooled super/luid and study the evolution of the solid. Gravitational effects can be

included in our equauons of motion. This constitutes a fairly realistic description of the solidification process.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-07-13

RESPONSIBLECENTER: JPL

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Proceedings

Elbaum. C., and Kosterlitz. J.M. "Kinetic and thermodynamic studies of melting-freezing of helium in mLcrogravity."

Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

11-1 71
[I. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

nt m t I.nal|ll|n.t .lltnl.l_|loolo|lonllnalnl||lona J|iollu|nlonao|_.l|ol. Jl.aul.l.llonno!lolnonl|nlllluIHIIon--Iloll0nlo|lloaaoloo H III*||O. 01HH|011e |lOl; 0|00|nl0|I|00UII.IIIIIOHIIIIII0nlII;Ul000n0001010aH00110|II|aI|0111|I0|

Theoretical Influence of Microgravity on Critical Fluid Measurements

PRINCIPALINVESTIGATOR: Prof. Richard A. Ferrell University of Maryland

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

This endeavor is tailored to provide theoretical support tor these current critical fluid microgravity Space Shuttle

experiments: the Critical Fluid Light Scattering Experiment (ZENO), the LeRC Critical Fluid Thermal

Equilibration Experiment (CFTE), and several other microgravity experiments are now in the definition phase.

TASK DESCRIPTION:

The science activity will examines six areas; three each for classical fluids and three eacb for super-fluid Helium.

Regarding classical fluidsl they are:

I. Short and long time scale equilibration driving Iorces.

2. The anomalous dimension critical exponent of the density fluctuation correlation length.

3. Shear viscosity near the liquid-vapor critical point.

Regarding super-fluids, they are:

1. A better prediction of the thermal conductivity temperature scaling.

2. The frequency dependence of the shear viscosity.

3. Theoretical insight into the unexpected temperature dependence or the second-sound velocity of 4He near its

Lambda transition.

This effort will employ a graduate student, a part-time post-doctoral fellow, and a visiting faculty fellow to assist in

this work.

TASK SIGNIFICANCE;

The results of the proposed study will both aid the interpretation of the data and demonstrate the need for the data

from the objective microgravity expertments, confirming science conclusions. The conclusions will greatly

improve the cost effectiveness of the science from identified flight experiments.

PROGRESSDURING FY 1994:

This task was extended only slightly into FY94 to "allow administrative closeout. All objectives were accomplished

by the end of FY93 and reported previously.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 0 MS Degrees: 0

PhD Students: 2 PhD Degrees: 2

TASK INITIATION: 1/91 EXPIRATION: 1/94

PROJECT IDENTIFICATION: 962-24-05-32

NASA CONTRACT NO.: NAG3-1180

RESPONSIBLECENTER: LeRC

i i i i i i Ii i i i i I i i i i i Ii iI I i lll I l I If I If I; iIi i; I II I I I I i i I I I I I Ill i i i I I I I I iii i i i i I I illI i l i i l lIIlll II I Illl I l lll II I I I I II Ill l lll II Ill I l le i; i I Illll l lll II I I I I; I I I I I II O II eI ii i ii i ii I Ii I lll I lll II I II II III I I I I l I I III I ImI I i I l lll II II I II I III II I II I I I I; I II II I I I I I I I I I

II-172
CondensateFraction in 5uperfluid Helium Droplets

PRINCIPAL INVESTIGATOR: Prof. J. Woods Halley University of Minnesota

CO-INVESTIGATORS:

C. Giese

C. Campbell

K. Goetz

University of Minnesota

University of Minnesota

University of Minnesota

TASK OBJECTIVE:

The scientific goal of the proposed project is to obtain information about the condensate fraction in superfiuid

helium four by studying elastic scattering of helium atoms from a freely floating macroscopic sphere of the fluid.

TASK DESCRIPTION:

During the second year we have initiated experiments on the use of C, covered surfaces to partially suspend He for a

ground based experiment. We are making computational studies of various magnetic suspension methods. Many

body c',dculations of transmission rates in the experiment have reached the stage of explicit numerical simulation,

which is under way in collaboration with S. Chin of Texas A and M.

TASK SIGNIFICANCE:

The condensate traction of the superfluid helium wavefunction is the microscopic manifestation of bose

condensation which is universally believed to be the origin of the fluid's superfluid properties (as originally

proposed by London more than 50 years ago). If successful, the experiment would be important because direct

experimental study of the condensate fraction has proved extremely elusive. Only neutron scattering experiments

give direct information and interpretation of these has proved difficult.

Our basic idea is that in a microgravity environment, it will be possible to do a tunneling experiment (analogous to

a Josephson tunnehng experiment in some respects) in order to study the condensate. We envision sending pulses

of gaseous helium atoms at one side of a suspended sphere of superfluid helium tour and detecting helium atoms

emerging in coincidence from the other side of the sphere.

PROGRESSDURINGFY 1994:

The objective of this project is the completion of a ground based study of the scientific and technical feasibility of

an experiment in which the presence and nature of the long range quantum coherence (condensate) in superfluid

helium four is detected. Pulses of gaseous helium will be fired at a suspended droplet of superfluid helium four and

the resulting emission of helium atoms will be detected.

Theoretical results from the previous fiscal year are reported in Halley and Campbell (PRL 1993), Campbell (JLTP

1993), Halley (JLTP 1993), and Halley (Physica 1994). This work suggested the existence of a large effect but "also

clarified the need for a more complete many body analysis of the problem. Analytical aspects of this analysis have

been completed in the past year and numerical work has been undertaken to make the needed variational calculations

with post doctoral visitor Sang Hoon Kim.

The first ground based experiment, undertaken in collaboration with I. Silvera of Harvard University, was finished

during this fiscal year. In this experiment, pulses of helium were fired at the horizontal surface of liquid helium at

one end of a U-shaped copper tube about 3 in in length and 0.25 in in diameter. A detector at the horizontal liquid

helium sttrface at the other end of the tube can detect re-emitted helium atoms. Mark Williams of this group spent

several months in Cambridge working on this experiment. The experiment, which was not ideal in several respects

l_i_e_ut_D_DD_n_uo_8_o_a_e_o_o_nQi_eu_e_u_e_8_e_ne_n_uu_n_8_I__IB_e_H_t_o_un_e_n_

11-173
with regard to observing the effect, did not show evidence Ior prompt re-emission of helium atoms from the surthce

at the remote end of U tube.

We are engaged in studies for two further types of ground based experiments. M. Williams is carrying out an

expertment at Minnesota to test the feasibility of a method for producing two parallel helium surfaces using the fact

that cesium surfaces are not wet by superfluid helium four. A capacitive bridge for measuring liquid levels has been

constructed and a preliminary, expermaent testing this idea will be run very soon.

Magnetic supsension has often been suggested as a method for droplet suspension of liquid helium in a microgravity

environment. Experiments at Brown are currently under way to achieve magnetic suspension of helium droplets on

earth using superconducting magnets. As an alternative J, Schmidt of this group has initiated a study of the

possibility of using permanent magnets for this purpose. If it can be achieved this method would have great

advantages with respect to simplicity and expense. It may even be possible to achieve suspension of helium droplets

on earth using permanent magnets. To study these possibilities, Mr. Schmidt has been developing computer codes

for determination of the optimum configuration of permanent magnets.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-07-14

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Campbell, C. E. Remnants of bose condensation and off-diagonal long range order in finite systems. J. Low Temp Phys.,

Vol 93, 907 (1993).

Halley, J.W. Structure of the condensate and some possible ways to observe it.. J. Low Temp. Phys.. Vol. 93, 893

(1993).

Halley, I. W. A novel approach to the observation of the condensate fraction in superfluid helium-four. Physica, Vol B97,

175 (1994).

Proceedings

J. W. Halley "Theoretical studies of manifestations of long range quantum coherence in 4He in atom-droplet interactions."

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

J. W. Halley "Ground based experiments to observe long range quantum coherence in superfluid 4He using atomic beams."

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Presentations

Campbell. C.E. "Recent developments in liquid helium-four ."

Many Body Theories, August 1994.

Eighth International Conference on Recent Progress in

Giese, C. "A novel approach to the observation of the condensate fraction in superfluid helium-four." Eighth A/AA

Symposium on Microgravity Science, Reno, Nevada. January 10-13, 1994.

Halley, J.W. "Formulations of the many body atom-droplet scattering problem." Workshop on Future Directions of

Quantum Many Body Theory, January 14-16, 1994.

Halley, J.W. "Looking for new experimental manifestations of long range quantum coherence in superfluid Helium-4."

Physics Colloquium, North Dakota State University, Fargo, ND, February 2, 1994.

Halley, J.W. "Looking for long range quantum coherence in superfluid helium." Physics Seminar at St. Olaf College,

Northfield. MN, March 23. 1994.

II-1 74
Halley. J.W. "Evaluating experimental ideas for observing long range quantum coherence in superfluid helium." Invited

talk at the American Physical Society Washington meeting. April 19, 1994,

Halley. J.W, "Looking for hmg range quantum coherence in superfluid helium," Condensed Matter Theory Seminar, Ohio

State University, Columbus. OH, April 18. 1994.

Halle',', J.W. "Evaluating experimental ideas for observing long range quantum coherence in superfluid helium."

Workshop on Quantum Fluid Clusters, Ringberg, Schloss, Kreuth-Oberhof, Bavaria, June 12-15, 1994.

Williams, M. "Ground based experiments on quantum coherence in helium-four." NASA Graduate Student Researchers

Program 1994 Annual Symposium. Washington, DC, May 11-13, 1994.

!I-175
Ultra Precise Measurements with Trapped Atoms in a Microgravity Environment

PRINCIPALINVESTIGATOR: Dr. Daniel J. Heinzen University of Texas, Austin

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The task objective tor FY94 is to trap laser-cooled Cs atoms in an "optical box" atom trap. During our preliminary

work, we have already demonstrated the trapping of 10 7 Cs atoms at a temperature of 100 t.tK in a magneto-optical

atom trap (MOT). During the upcoming year we plan to design and to implement the lasers and optics required to

generate an "optical box", which will be formed by six intersecting, elliptically focussed laser beams. We also plan

to demonstrate that atoms from the MOT can be confined to the interior of this box. This constitutes the first step

to realize our ultimate goal, which is to develop instruments and techniques that can be used to carry out precise

measuremenL_ with atoms trapped in such a box, in a zero-gravity environment.

TASK DESCRIPTION:

In order to demonstrate the "box" trap, the Cs atoms will first be captured in a magneto-optical atom trap (MOT).

This trap can easily capture about 10 7 atoms into a 1 mm 3volume directly from a very dilute room temperature Cs

vapor. The Cs atoms will then be released from the MOT, and begin to fall under the influence of gravity. At the

instant they are released, the optical box trap will be turned on. thus capturing a large fraction of the atoms from the

MOT. The box trap will be fo_Tned by six laser beams of elliptical cross section, that are tuned to the high

frequency side ofa Cs optical resonance line. These beams will be generated from a Ti:sapphire laser, prism beam

expanders, and focussing optics. They will be intersected so a_sto form a cubical surface of light. Atoms striking

the "walls" of the cubical surface will experience a repulsive optical dipole force that confines them to the interior

of thebox.

TASK SIGNIFICANCE:

Precision atomic resonance devices have tremendous practicaland scientific importance. An important example is

the atomic clock, which has widespread applications to navigation, geophysical measurement, and astrophysics.

Precise tests of fundamental scientific principles such as time-reversal symmetry are also carried out with such

devices. Substantial advances in the accuracy of these devices are therefore of great maportance. One very promising

avenue is to make use of ultracold, laser-cooled atoms. These atoms can move as much as 10,000 times more

slowly than the atoms in conventional devices. This very low velocity can in principle substantially increase the

accuracy of an atomic resonance device. This is because certain measurement errors are propo_ional to the velocity

of the atoms. Unfortunately, gravity seriously limits the usefulness of laser-cooled atoms for this purpose, because

it quickly accelerates the atoms to back to high velocities. Thus, only in the gravity-free environment of space can

the full potential of these ultracold atoms be realized. Our goal is to develop techniques that could be used to

produce and store a large number of ultracold atoms in the gravity free-environment of space. If successful, atomic

resonance devices based on these techniques could lead to dramatic increases in accuracy.

PROGRESSDURINGFY 1994:

The start date for this project was Sept. 7, t994, and only a few weeks have elapsed since this date. However, some

initial work on this project was carried out prior to the start date. During this time, we have built a magnetically

shielded magneto-optical atom trap, and used it to trap 107 Cs atoms at a temperature of about 100 _tK. The trap

consists of a Cs vapor cell that is evacuated to a pressure of 10 s tort with an ion pump. Laser beams from two

frequency-stabilized, grating-tuned diode lasers are used in conjunction with a quadrupole magnetic field to trap and

cool that atoms from the background Cs vapor. We are currently carrying out Zeeman resonance experiments on

these atoms, and are designing the optics to produce the "box" trap discussed in the task objective.

_I_I_in_u_I_I_l_D_Iui_I_I_q_II_IIw_u_iin_*_I_u_o_iI_D_u_j_I_i_uj_iniu_u_I_i_Ii_I_i_I_in_ittn_n_i_n_n_u_i_nn_n_i_ei_i_nI_

II-176
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

Jlllllllll.llll||llonl|llllnlul_ol.lnnll.l.llvl|H.l||n.llllll0111|lllnl. jIj_"_"_O_ni_Ij_e_I|"_II_;_|_|_I_o_u_I_"_"_D_I!_I_Èun_e_!_| .llnvllll|ll_|n.llllllll|nlllJlll._llllolI.OI ..!

STUDENTS FUNDEDUNDER RESEARCH:

BS Studenk_: 0

MS Students: 0

PhD Students: t

TASK INITIATION: 9/94 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 962-24-08-14

NASA CONTRACT NO.:NAG8-1090

RESPONSIBLECENTER: MSFC

II-177
Dynamic Measurement Near the Lambda-Point in a Low-g Simulator on the Ground

PRINCIPAL INVESTIGATOR:Dr. Ulf E. Israelsson Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

R.V. Duncan Sandia National Laboratory

TASK OBJECTIVE:

The objective or' this work is to perform dynamic measurements on a short cylindrical sample of helium very near

the lambda-point in an effective gravity environment of about 0.01 g. Dynamic conditions will be created by

passing a heat current through the sample. The effective low-gravity environment will be created by applying a

magnetic field gradient which closely cancels hydrostatic pressure differences in the sample. Specifically, the

reduced gravity conditions will enable a test of theoretical predictions of the effect of small heat currents on the

nature of the lambda-transition and will allow probing of the interface region between co-existing normal and

superfluid portions of the fluid. These measurements are not possible to perform in a regular lab environment on

the earth due to the inlluence of hydrostatic pressure effects and the need to apply large heat currents to overcome

hydrostatic effects, tending to perturb the fluid sutficienfly to render the measurements questionable. The

suppression of the lambda-transition due to heat currents will also be investigated at lower values of the heat current

than possible in a one-g environment. The magnet will be procured from a magnet winding company and installed

in a thermal platform under construction at JPL. Melting curve thermometers, which can operate well in strong

magnetic fields, will be used lot high resolution thermometry.

TASK DESCRIPTION:

The magnet will be designed and constructed by a magnet winding company. An experimental cell will be

constructed with attachment point.s tot melting curve thermometers to enable high resolution thermometry to be

performed in the high field conditions of the experimental cell. The melting curve thermometers will be constructed

at Sandia under a sub-contract to JPL. A high pertormance thermal platform will have the experimental cell and the

magnet installed into it lor pertbrming the measurements. A vibration isolated and magnetically shielded helium

dewar will be used to cool the thermal plattorm in order to mintmize noise generation and improve the fidelity of

the collected data.

TASK SIGNIFICANCE:

Recent investigations of the influence of an applied heat current on the properties of helium near the superfluid

transition have revealed many new phenomena. Agreement with theories based on scaled mean field calculations

and dynamic renormalization group calculations is not good. The disagreement may stem from the fact that theories

assume zero-gravity conditions, while experiments are pertormed in a one-g environment. To overcome the

influence of gravity on properties near the transition in a heat current, large values of heat current are required which

has detrimental effects on the very properties in need of study. It has also been predicted that imposition of a heat

current will change the very nature of the lambda-transition from continuous to first order. Investigating these

phenomena in a simulated low-gravity environment would enable lower heat currents to be used and would enable

observation of phenomena washed out by gravity effects.

PROGRESSDURING FY 1994:

The high field gradient superconducting magnet was delivered from the manufacturer in FY 94. Prior to delivery,

the magnet was tested at the vendor facility to verily that all requirements had been met. The magnet was

successlhlly operated up to 16.5 tesla at 2.2 K without quenching Ior a maximum field times lield gradient product

of 23 TZ/cm. This is exceeding the requirement by nearly 10%. At JPL the magnet was installed in the thermal

plattorm, cooled down, and performance tested. We experienced some quenching problems, releasing about 150,000

Joules of energy, when operating the magnet at near full field. The quenching problem was traced to a design flaw

_j_Iu_u_I_n_u_u_Q_ni_n_uID_s_n_n_n_*_Iu_u_Q_i_n_uu_inI_nIu_i_lI_i_n_I_1_Iu_n_I_ii_i__

11-178
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

with the "home made" current leads which we now believe to be solved. Field protile data was gathered using a hall

probe device which was movable along the axis of the magnet. A second probe was used slightly off-axis to verify

the performance over the entire expertinental region.

The design and component fabrication of the thermal conductivity cell to be used in the experiments was also

completed. The cell is 0.5 cm long and 0.5 cmm diameter and is made of stmnless steel with copper end plates.

The stainless steel side wall is 0.005 cm thick and has two circumferential temperature probes spaced evenly along

the length of the cell. Final assembly of the ceil is underway.

Six melting curve thermometers complete with reference capacitors have been constructed. Four of these

thermometers will be used to measure the temperature of the two mid-plane thermometers, the top copper end plate,

and the heat current control platform to near nanokelvin resolution.

To be able to better plan and analyze the low gravity simulator expenmenls, we have developed computer code to

numerically simulate a one-dimensional thermal conductivity cell of helium near the lambda point. The basic time

dependent heat flow equations and the known thermodynamic properties of helium at the lamNla point were used.

The effect of gravity was included by varying the spatial distribution of the loc_d transition temperature in the cell

accordingly. The results clearly demonstrate that a reduced gravity environment more closely achieves a quasi-static

experimental condition.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-04-09

MS Students: 0 RESPONSIBLE OENTER: JPL

PhD Students: l

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Israetsson. UE., Strayer, D.M., Chui, T.CP.. Larson, M, and Duncan, R,V, Dynamic measurements near the

lambda-point in a low-gravity simulator on the ground Physica B, vol 194-196, 593-594 I1994_.

Presentations

Larson, M,, and Israelsson. U.E

reduced gravity environments."

"Simulations of the lambda transition of Helium-4 with :ui applied heat fh)w for I g and

1994 March meeting of the American Physical Society.

Larson, M., and lsraeIsson. U.E. "The lambda point in a [ow-g si.mulator - progress report, The lt_94 Microgravity Lt)w

Temperature Physics Workshop, Washington D.C.. January. 1994.

I1-1 79
Turbidity of a Binary Mixture Very Close to the Critical Point

PRINCIPALINVESTIGATOR:Prof. Donald T. Jacobs The College of Wooster

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

This experimental activity is intended to measure the light transmitted through a near critical fluid consolute point

of a density matched binary, mixture.

TASK DESCRIPTION:

1. Develop a room temperature thermal control system for the sample that enables temperature control inside of ±

3_tK.

2. Assemble and use a phase sensitive detection system to detect the small light intensity variations expected close

to the consolute point.

3. The turbidity data will be reduced according to the formalism of P. Calmettes et at. {Phys. Rev. Lett. 28, 478

(1972)};.

4. Undergraduate students will assist Prof. Jacobs, making his activity a strong educational experience for the

student_.

TASK StGNIFICANCE:

The resulting data will be used to cont-n'm and quantify a small exponent "q" in a denominator "{ l+(q_ )z-_} that

describes the correlation length dependent distribution of scattered light from near critical fluids. Also, '=two-scale

universality" can be tested from the data set.

PROGRESSDURING FY1994:

"l-he optical system can now resolve the small light intensity variations anticipated in this experiment, The optical

components rest on a vibration-isolated optics table. Using an intensity stabilized laser beam that is split and then

chopped into a reference and signal beam, the stability of measured intensities is less than the requisite 0.1percent.

Lock-in amplifiers provide the sensitive detection of the photodiode signals.

The cell was redesigned to reliably seal the fluids yet allow light m pass through a 2ram thick slab of fluid. Once

the critical composition for the liquid mixture is loaded into the cell, it will be suspended in a series of nested

cylinders, each of which will stabilize the temperature fluctuations of the adjacent outer stage by a factor of 100

using an active temperature controller, The temperature controllers have been built and tested and the temperature

sensors have been calibrated.

The computer software that accesses the instruments used in the experiment has been written in the language

LabVIEW. Each portion of the program has been tested and debugged and the main controlling program that links

the many sub-elements is being developed.

Associated experimental investigations that provide comparative information on other properties of binary liquids

are being used to test "two factor universality." Coexistence curve and heat capacity data have been taken and are

being analyzed for publication.

,,_,8oC4-,.3.
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

JlJllloBt illl J it u llllllllllmllell ill j oI_I_i_i_M_i_j_ii_"_"_o_i_iOi_"_j_oI_I_I_lli_o_i_I_M_i_e_lM"l_l_i1_"I_m_iI_I_ .lllllllllllllllJf I.IIItlll.lllll.d. IIIIIIIIl|lllllllllllllllllllll.lllll

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

BS Students: 7 BS Degrees: 2 PROJECT IDENTIFICATION: 962-24-05-74

MS Students: 0 MS Degrees: 0 NASA CONTRACT NO.NAG 3-1404

PhD Students: 0 PhD Degrees: 0 RESPONSIBLE CENTER: LeRC

II-I 81
Atom lnterferometry in a Microk, ravity Environment

PRINCIPALINVESTIGATOR: Dr. Mark A. Kasevich Stanford University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

Our scientific objectives are: (1) to develop a rugged laser cooled source of atoms using DBR (distributed Bragg

reflector) laser technology; (2) to use this source and these lasers to demonstrate coherent atom wavepacket

manipulation techniques; and (3) to incorporate these techniques into an atom interferometer gravity gradiometer.

We plan to experimentally study the per/brmance of the prototype device to evaluate the feasibility of a space-based

system.

TASK DESCRIPTION:

In year one of the grant period we will develop the laser sources and apparatus needed for the proposed experiments.

We will employ standard laser cooling and trapping techniques with atomic cesium to create the cold atomic source.

Our tirst expertiments, to be carried out near the end of year one, will locus on demonstration and characaterization

of the proposed coherent atom manipulation techniques. In year two we will demonstrate and characterize an

interferometer accelerometer - first in a low sensitivity regime in order to study potential systematic phase shifts and

subsequently in a high sensitivity configuration to explore the potential accuracy and resolution of the device.

Since vibrational noise will severely hamper the performance of an Earth bound accelerometer, we will switch to a

more complicated gradiometer geometry which is tar less sensitive to vibrational noise in the final stages of the

proposed work.

TASK SIGNIFICANCE:

The convergence of recent advances in the field of laser manipulation of atoms with technological developments in

the electronics/opto-electronics industry opens the possibility of a new class of experiments involving laser

manipulated atoms in a microgravity environment. In the past five years, light-induced forces have been used to

cool ensembles of atoms to temperatures below 1 [.tK, providing researchers with a novel source of ultra-cold

atoms. These laser cooled sources have revolutionized experimental atomic physics and have led to new classes of

precision time standards and inertial sensors. Application of these techniques in a microgravity environment could

result in robust gravity gradiometers and gyroscopes with sensitivities exceeding current state-of-the-art devices by

several orders of magnitude. Such instruments would have important applications in a number of fields. For

example, satellite gradiometry studies yield important geophysical data concerning Earth and ocean dynamics. A

satellite borne accelerometer/gravimeter used in conjunction with the GPS system could be used to obtain highly

accurate maps of the global Earth gravity field. In addition, techniques developed for satellite interferometer sensors

might also have terrestrial applications in, for example, mineral/oil exploration and navigation. Finally, with

minor modification, the techniques could be employed to develop atomic standards with unprecedented accuracy.

PROGRESSDURING FY 1994:

This grant has recently been initiated, and budgeting arrangemenL_ are still in process.

i i i ii i III I i I IS i I I I I III I I IJIli II I I|l I Illl I I I I I I I I I I I i IIII I III I III I I I II I I I I I I I I I ii II ii I I ii I I I IiI I II I II I I i ill II! II I lI I I I I I I III II I I I I I I II I I I II I l III I I I I I III I II I II I Jl I II I II III I II I II I I IIII III I Jl I II IIII I II Ill lil III I lU III Ill I I IIII I I I III III Ill III Ill I II II

II-182
STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 9/94 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 962-24-08-15

NASA CONTRACT NO.:NAG8-1088

RESPONSIBLECENTER: MSFC
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

H .:ulol.:oo:.l:.l.lnt Jlollol.l.llolnl:.R. Jllnl*l:.:u.:|l:not*olJoHoool--I:ll:ot:onH JlollHI*. a o .O .olll:a.*a61Jom.n--n:u:a--:--I.:u:loooa.l.a.lJo:--Jlllllolnot .ll|lllllOlHl.n|l:.llllouololI"i*lllllulo" ons.lool*..

Effect of Confinement on Transport Properties by Making use qf Heium Near the Lambda Point

PRINCIPALINVESTIGATOR:Prof. John A. Lipa Stanford University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this project is to study the effect of confinement on the thermal conductivity of helium near the

lambda point. The thermal conductivity is a transport property most readily accessible to precision measurement,

tallowing the effects of confinement to be quantified. The extent to which the results could be improved in a

microngravity environment will also be studied.

TASK DESCRIPTION:

Dohm and collaborators have predicted the first order departures of the thermal conductivity from the bulk behavior

as on approaches the lambda point. As the transition is approached, the relevant length scale increases dramatically,

:allowing the effect to be measured in conventional apparatus. Higher order, nonlinear effects are also predicted, but

quantitative information is not yet available. We plan to measure these effects for confinement in parallel plate

geometry as a function of plate separation. Earlier measurements indicated that the first order effect was different to

that predicted. This needs to be verified, and higher order contributions need to be explored.

TASK SIGNIFICANCE;

The results will be used to test the emerging theory of transport properties in contined geometries, which has

application to physical and chemical processes near surfaces or in small channels.

PROGRESSDURING FY 1994:

Funding for this research became available at the beginning of FY95. Progress to date included investivations of

previous thermal conductivity data to look for possible finite size effects. Expertments with helium confined within

gaps as small as 70 microns have been examined.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 0 MS Degrees: 0

PhD Students: 3 PhD Degrees: 1

TASK INITIATION: 9/94 EXPIRATION: 8/96

PROJECT IDENTIFICATION: 962-24-04-14

RESPONSIBLECENTER: JPL

nu| nno | no no ni| ! |in a no! I ooool Ill ol nno nI oonnonnn| a* naoI ao i u=nn* na| nnI nI || nnoi noI anni noi no naI I a=I aI uuI ! an| ! unnnIn nuunt uuouuI | uoogo I aa! I onnl nnnuoI Oil OnnOUUI ! no nUOU! | nI nO!O! ! onl | uOnnOnno !|! aol I on ni! u|n I no I I! I H I oll oll ou! i I aol nononol nao n! oI uoil oi !in a

II-184
Theoretical Studies of the Lambda Transition of Liquid 4He

PRINCIPALINVESTIGATOR: Prof. Efstratios Manousakis Florida State University

GO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

We study the critical properties of liquid helium near the superfluid transition temperature T_. using recently

developed numerical simulation techniques and finite-size sc',ding. In parucular, we are interested in the scaling

behavior of the superfluid density and the specific heat. We shall study different finite geometries, namely pure

two-dimensional, pure three-dimensional and the crossover from two-dimensional to three-dimensional superfluidity

in order to verily the validity of scaling and to determine the universal functions associated with scaling.

TASK DESCRIPTION:

A recently developed updating technique called cluster Monte Carlo, which elliminates the long-standing problem of

critical-slowing-down will allows us to approach close to the lambda point tor large size lattices and, thus, extract

the critical exponents and scaling properties of the physical quantities of interest. We shall study the temperature

and the finite-size dependence of the supertluid density and the specific heat. From these studies we can determine

the critical exponent using finite-size scaling techniques.

In addition we shall determine the superfiuid/normal phase boundary T;_(h) for films of thickness h. We shall

calculate, the supertluid density as a function of the film thickness and we shall exanune the validity of the

finite-size scaling theory. We shall also calculate the specific heat as a function of h and this will be used to

understand the results of the CHeX experiment.

Finally, the role of vortices and the Kosterlitz-Thouless scenario will be also examined in the course of this work.

We shall calculate the renormalization group beta function for two-dimensional superfluids and we shall compare it

to that predicted by the Kosterlitz-Thouless theory. In addition, we shall study with our simulation technique the

intimate connection between the superfluid transition and the unbinding of vortices.

TASK SIGNIFICANCE:

The results of these studies are relevant and will be compared to the experimental measurements obtained from the

lambda-point experiment (LPE) and to the confined helium experiment (CHeX).

PROGRESSDURINGFY1994:

Using the x - y model and a non-local updating scheme called cluster Monte Carlo, we calculated the supertluid

density r and the specific heat c of a superlluid in a t'tim geometry, i.e. on a finite lattice of size L x L x H (where L

>> H). In this geometry the superfluid density shows a three to two-dimensional crossover behavior. This means

that below a certain crossover temperature the helium film behaves as if it was infinitely thick and, thus, it exhibits

three-dimensional behavior. Above the crossover temperature and still below the bulk critical temperature T_ the

helium film shows two-dimensional behavior. Because of that the critical temperature is reduced, the supertluid

phase transition occurs at temperatures To(H) smaller than T1.These reduced temperatures depend on the thickness of

the helium film. In order to determine the critical temperatures To(H) we applied the Kosterlitz-Thouless-Nelson

(KTN) theory, which was formulated for purely two-dimensional helium films, to the quantity T/(Hr). Namely, by

solving the KTN renormalization group equations for this quantiyy we were able to obtain the values T/(Hr) in the

limit as L tends twards infinity; thus, the dependence on the planar dimensions L of the lattice was completely

eliminated and T/(Hr)(H) is a/'unction of the film thickness only. We found that for a fixed film thickness H the

ratio T/(Hr)(H) close to T_(H) obeys a simple functional form. Fitting this functional form to the computed values

II-185
for T/(Hr) we fimnd estimatE,s for the critic_fl lemperatures T=(H). The detailed results of this work have been

submitted for publication m Phys. Roy. B.

The crossover behavior Ibr the specific heat c is much less pronounced. Lattices with L=60 are large enough to

represent the infinite fihn thickness limit. For the films with H=6,8,10 we obtain a universal curve that relates the

heat capacity for films of finite thicknes to the heat capacity of infinitly thick films. We are in the process of

comparing our universal function with experimental results. The results of this investigation will be submitted to

Phys. Rev. B.

The computations described above were carried out on the x-y model with periodic boundary conditions in all

directions. This ensures the homogeneity of the physicN quantities along the film thickness. For such a system we

verify the validity of the finite-size scaling theory as reported above. However, in experiments on thin helium films

which test the finite-size scaling theory, 4He is supported by substrates which impose different boundary conditions

on the film. It appears therefore necessary to investigate the influence of other boundary conditions on the scaling

behavior of the superlluid density and the specific heat with respect to the film thickness. From these investigations

we hope to gain insight as to why recent experiments on thin helium films seem to yield results contradicting the

finite-size scaling theory.

We have repeated the calculations described above for the x-y model in a film geometry with staggered

(Dirichlet-like) boundary conditions in the top and bottom layer of the film. The superfluid density develops a

profile with the maximum value in the middle of the film. At the boundaries the superlluid density vanishes. We

have identified the temperature region where the model displays two-dimensional behavior and have used the KTN

theory to determine the critical temperatures T_(H). Furthermore our data for the superfluid density and the specific

heat do not collapse onto one universal curve until we applied an effective critical exponent n=0.923. It seems that

these preliminary results show the same situation here as was described by Rhee, Gasparini and Bishop who had to

use an effective critical exponent n=1.14 to achieve scaling of their data for the superfluid density with film

thickness. However, we are in the process of trying to understand these results further.

The calculations reported atx_ve were performed on a heterogeneous Environment of workstations which include

DEC Alpha, Sun, and IBM RS/6000 works_alions and on _he Cray-YMP supercomputer and took several months of

CPU time.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 01/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-07-15

RESPONSIBLECENTER: JPL

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Schultka, N., and Manousakis E.

Schultka, N., and Manousakis, E.

Rev. B, (submitted).

Schultka, N., and Manousakis, E.

Schultka, N., and Manousakis. E.

effects.

Finite-size scaling in two-dimensional superfluids. Phys. Rev. B, vol 49, 12071 (1994).

Crossover from two-dimensional to three-dimensional behavior in superfluids. Phys.

Finite-size scaling of the specific of superfluids. Phys. Rev. B, (submitted).

Crossover from two-dimensional to three-dimensional behavior in superfluids-boundary

Phys. Rev. B., (submitted).
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

Proceedings

Manous_is. E. "Numerical simulation of scaling in superfluid films." Proceedings of the NASA/JPL 1994 Microgravity

Low Temperature Physics Workshop.

Schuhka, N., and Manousakis E. "Finite-size scaling of the superfluid density in two-dimensional superfluids."

Proceedings of the 20th Internati_mal Conference on Low Temperature Physics.

Presentations

Manousakis. E. "Numerical simulation of scaling in supert'luid films." 1994 Microgravity Low Temperature Physics

Workshop, Washington, D.C. January 18-21, 1994.

Schultka, N. "Finite-scaling of the supert'luid density in two dimensions and thin films." Max Planck Institut fur Physik.

Munich. Germany, December 1993.

Schultka, N. "Finite-scaling of the superfluid density in two dimensions and thin films." Institut fur Theoretische Physik,

RWTH Aachen, Aachen, Germany, December 1993.

Schultka. N. "Finite-scaling of the superfluid density in two dimensions and thin films." Institut fur Kemphysik, TU

Wien, Vienna. Austria, December 1993.

Schultka, N., and Manousakis. E. "Crossover from two to three dimensions in superfluid films." APS Meeting, Pittsburgh

PA. March 1994.

Schultka, N., and Manousakis, E. "Finite size scaling in two-dimensional superfluids." APS Meeting. Pittsburgh PA,

March 1994.

I I l II I II i II I Oi II Iill I i i i ii I |11 Ill | Ol l oI iii i lil i ii * i I I | ii I l i i I I ii iI I I I I i i l il ii I ii l i i ill i i i l ii i iii I* ! i iiii ii i Ii i iii ii i l eI I I I I ei Iii i IIi; ii I i i I I iitl lilll OOII I I I II I II I I I I I * ! I I I I I I I II I* I I I I I II II I I I I I I! II II I I I I ! l I I I II I I I I I I II I II I I I ! I I I I I I I I II I I I I I I I I e

II-187
Dynamics and Morphology of Superfluid Helium Drops in a Microgravity Environment

PRINCIPALINVESTIGATOR:Prof. Humphrey J. Maris Brown University

CO-INVESTIGATORS:

G. Seidel Brown University

TASK OBJECTIVE:

The long range goal of our research is the study of the hydrodynamics or drops of superfluid liquid helium by means

of ruler!gravity experiments conducted in space. At the present time we are developing a series of earth-based

experiments to levitate superfluid drops so that we can acquire data and experience that will be needed/br the design

of experiments in space.

TASK DESCRIPTION:

We are conducting a series of earth-based experiments to study the behavior of supertauid drops. We will develop a

means to levitate helium drops in earth gravity, primarily by magnetic levitation. We will then investigate 1) how

to inject and position drops in a ruler!gravity chamber, 2) how to manipulate drops and to give them angular

momentum, 3) how to observe accurately the vibrations and rotations of the drops, and 4) what drop sizes are best

suited for the study of a variety of phenomena.

TASK SIGNIFICANCE:

The goal is to achieve data and experience critical for the design of experiments in space.

PROGRESSDURINGFY 1994:

Optical Levitation Experiment: We have completed our experiments on optical levitation of superfluid helium-4.

Drops of diameter approximately 20 microns were levitated using an optical trap formed by a focussed Nd:YAG

laser beam of wavelength 1.06 micron. It was possible to levitate drops for as long as three minutes. We have

carried out a detailed analysis of a number of phenomena observed during this experiment. Several lactors that might

control the rate at which the drops evaporated were analyzed, including laser heating, evaporation due to the curved

surface of the drop, and non-equilibrium conditions inside the experimental cell. We pertormed detailed computer

calculations of the potential energy in the vicinity of the optical trap. The experiment revealed that it was possible

lor several drops to be held in the trap at the same time without coalescence occuring. We considered a number of

possible explanations for this remarkable result. A paper on the optical levitation experiment will appear in the

Journal of Low Temperature Physics. In addition, the staff of Scientific American have written a short article about

the experiment to be included in a forthcoming issue of their magazine.

Magnetic Levitation Apparatus: We have continued construction of the apparatus to magnetically-levitate helium.

The magnet constructed by Oxford Instruments has been delivered. The large Jams dewar for the magnet has been

mounted and the cryostat is under construction. The cry!slat is mounted adjacent to a large optical table on which

we can mount lasers/br illumination and an optical recording system. This cry!slat has been designed to be suitable

tor a variety of experiments on helium drops, at temperature down to 0.5 K.

Fluid Mechanics of Drops in Micro-Gravity: We have started a calculation designed to determine the morphology of

a supertluid drop with angular momentum under micor-gravity conditions. The goal is to determine how the shape

of the drop changes as the angular momentum is increased. For the moment we are restricting attention to

consideration of the shape with lowest energy for a given angular momentum.

i i i I l i i i ii aI l i l I I oI I aI el Il I Ill I el el I II I I I I I I l I I l ii i ii i Ill I I I I II II I I I I I I I I I I |lli !|111111111111 iii oi i i i i el e!I l I ! I l! I i sI Ii ! el! oi (Oil ! oi Oli I ! i ooI i oi l !I l ii ! i l i i i i i i I I oI; i iii i oi i I II I iI I I I I l I I I I i i i i i ii i i i i i t i i i i i el I I I i i i i. I I I I I IU I I I I I I II I I I l ai I i i i ii i i

11-188
II. MSAD Program Tasks -- Ground-based Research Dis_pline: Benchmark Science

j"n_l_||_n|_i_n_|_"_nnn_|_I"_"_"i"_Hi"I_"_"n"I_n_"n"_"_i_"_i_"_n_"_|_"_"_ .i.ii.l.n.n.I.In0_.l.ll.alt lallaoot.l.lalll.ll0ol, nl.a.nPol.n. HIJ.ll_llllaOll.iHn.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-07-16

MS Students: 0 RESPONSIBLE CENTER: JPL

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Weilert, M.A., Whitaker, D.L.. Maris, H.J., and Seidel. G.M. "Optical and magnetic levitation of supert]uid heliuln

drops." Proceedings of the NASAJJPL 1994 Microgravity Low Temperature Physics Workshop.

lallllllOlOllllll!lllllllelOlOlllOOOlllOllOlll!llllnall nelglllO!aOolla!l!lltllOll!alllll!OlllllllalllOllaln aolt IlOOIlaOl!ll!lll!lalllOlOllllOllllllllllt lltlllllUllalllllnllt ilUOit olin lot i!t t lllllt it It el I In Inela IIOgllllllllt IlU!OOOt t oleo!oo Ill nel a

ii-189
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

a l tl_lllll i aln i oil ii i iii ilu a o u i ollulll tlo t la 1 ii i I| iii a lll i i11 a i I a I ni l u,. n a o l .I I Ill i II I aalllu, Ol,l| I IIII u lll I Ig I Iollul_l I f ol_l i_lfl_r I_ l aafllll_ f I; I al I a l I_l l ai I f lafllfJl Ill I llllllalalll_lf filllll_lf_lfllill luf Ill_t r ii_llf_lil_flf_.lll_

Critical Transport Phenomena in Fluid Helium Under Low Gravity

PRINCIPALINVESTIGATOR:Prot. Horst Meyer Duke University

CO-INVESTIGATORS:

F. Zhong Duke University

TASK OBJ_6TIVE:

Ground-based experiments will be carried out to study the density equilibration process at constant average density r

in a pure fluid, (_He), near its liquid-vapor critical point (T¢, r_) after a step change in temperature DT of the

container walls. Measurements are to be carried out for both the region above T_ (one phase) and below T_

(coexisting phases). Numerical simulations are to be performed of the density, temperature and pressure

equilibration processes in _He for the regime above T¢, both ground-based and under reduced gravity. The

measurements are to be extended to binary (_He-4He) mixtures near their liquid vapor critical point ("plait point").

TASK DESCRIPTION:

Two flat, horizontal cells of somewhat different geometry are used in different series of experiments. The fluid is

contained between two parallel flat OFHC copper plates with high thermal conductivity, kept at the same

temperature that is regulated to within a few mK before and after the step DT. In both cells, the fluid layer height is

approximately 4 ram, the diameter is 30mm and the density is measured by two thin horizontal superposed

capacitive sensors, spaced by 2 mm that record the dielectric constant. The density is then derived via the

Clausius-Mossotti relation, and is recorded by both sensors, r,op(t) and r_,om(t), as a function time t after a

programmed small temperature step of the cell walls. At temperatures above T¢, immediately after the step DT, the

fast density change from adiabatic energy transfer ("piston effect") followed by the slow stratification change at each

sensor are recorded by computer. Experiments

are carried out along several near-critical isochores and along several isotherms. Below T¢, the two sensors detect

respectively the coexisting liquid and vapor phases. An induced temperature change in the cell walls will permit

following the density evolution in both phases with time.

With help of the known scaled expressions for the static and transport properties of 3He above T¢, numerical

simulations in one dimension are carried out to predict the temporal and spatial evolution of the thermodynamic

parameters (density, temperature, pressure and their derivatives) and predict the asymptotic relaxation times. This

simulation is to be done at arbitrary values of the gravitational acceleration g.

After completion of the _He program, measurements and numerical simulations are to be extended to binary (3He

-_He ) mixtures.

TASK SIGNIFICANCE:

Such studies - both for pure fluids and binary mixtures - are very relevant to experiments on fluids under mg

conditions, where investigations of static and dynamic properties near critical points are to be carried out. It is

important to know how long a fluid system takes to approach closely enough thermodynamic equilibrium, and

what are the basic mechanisms that control the equilibrium process. The numerical computations above T¢ are to be

compared with experiments. Simulations under microgravity conditions will be able to assess the permissible

temperature ramping rate in experimental data taking that will enable measurements of critical properties in a

quasi-equilibrium state. In the two-phase regime below T_, little is known about the equilibration dynamics and the

proposed experiments are expected to substantially help in understanding these processes.

I I i I I II I I I I I I I I I I I I I I II ii I I I I 111111 Ill I I I I I I I I II I I I I I I I I I i I II i I l I i I I I I I I i i iI I I Ii I I I I I I I i i ii i Ii i I I I I I i I I i i II i Ii I I I I I I I II I II I I I I I I i i I I I II I I i i I I i I i I iI II I I I i I 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 I

II-19 0
II. MSADProgram Tasks -- Ground-based Research Discipline: Benchmark Science

PROGRESSDURINGFY 1994:

During spring '92, the existing cryostat for work over a temperature range 1-5 K (previously used in the

NASA-sponsored viscosity measurements) was modified to incorporate a temperature-regulated platform supporting

the density equilibration cell. Electronic circuitry was installed for high-resolution stable temperature and dielectric

constant measurement arrangement. Computer programs for temperature step control and automatic data acquisition

and reduction were developed. The apparatus was tested over a period of several months, and data-taking routine was

developed and gradually perfected, hntial density straufication data were taken in the one-phase regime 'along the

critical isochore and also in the two-phase regime. Temperature steps of different sizes and sign were used and the

stratification data were analysed in a prelmainary fashion. Stratification time was found to diverge as the critical

point is approached from both the single and the two-phase regimes. At a given temperature, it was found to be the

same coming from either the colder or the warmer side. We expect to continue with data taking along other

isochores and along isotherms, and hope to present a scaling scheme of our data.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 2/92 EXPIRATION: 1/94

BS Students: 0 PROJECT IDENTIFICATION: 962-24-02-01

MS Students: 0 RESPONSIBLECENTER: JPL

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Howald, C., Qin, X., Nham, H.S., and Meyer, H. Shear viscosity measurements of liquid 4He and 3He-4He mixtures near

the tricritical point. J. Low Temp. Phys., vol 86, (1994).

11-191
Equilibration in Density and Temperature Near the Liquid-Vapor Critical Point

PRINCIPALINVESTIGATOR: Prof. Horst Meyer Duke University

CO-INVESTIGATORS:

F. Zhong Duke University

TASK OBJECTIVE:

Ground-based experiments will be carried out to study the density equilibration process at constant average density r

in a pure fluid, (3He), near its liquid-vapor cntic'al point (To,re) "after a step change in temperature DT of the

container walls. Measurements are to be carded out for both the region above T_ (one phase) and below T_

(coexisting phases). Numerical simulations are to be performed of the density, temperature and pressure

equilibration processes _He for the regime above T_, both ground-based and under reduced gravity. The measurements

are to be extended to binary (_He-"He) mixtures near their liquid vapor critical point ("plait point").

TASK DESCRIPTION:

Two fiat. horizontal cells of somewhat different geometry are used in different series of experunents. The fluid is

contained between two parallel fiat OFHC copper plates with high thermal conductivity, kept at the same

temperature that is regulated to within a few mK belore and after the step DT. In both cells, the fluid layer height is

approximately 4ram, the diameter is 3lknm and the density is measured by two thin horizontal superposed

capacitive sensors, spaced by 2 mm that record the dielectric constant. The density is then derived via the

Clausius-Mossotti relation, and is recorded by both sensors, r,o, and r.o.om (0, as a function time t after a

programmed small temperature step of the cell walls. At temperature above T_, immediately after the step DT, the

fast density change from adiabatic energy transfer ("piston effect") followed by the slow stratification change at each

sensor are recorded by computer. Experiments are carried out along several near-critical isochores and along several

isotherms. Below T_, the two sensors detect respectively the coexisting liquid and vapor phases. An induced

temperature change in the cell walls will permit following the density evolution in both phases with time.

With help of the known scaled expressions for the static and transport properties of _Hc above T_, numerical

simulations in one dimension are carried out to predict the temporal and spatial evolution of the thermodynamic

parameters (density, temperature, pressure and their derivatives) and predict the asymptotic relaxation times. This

simulation is to be done at arbitrary values of the gravitational acceleralaon g.

After completion of the _He program, measurements and numerical simulations are to be extended to binary

(3He-"He) mixtures.

TASK SIGNIFICANCE:

Such studies - both for pure fluids and binary mixtures - are very relevant to experiments on fluids under mg

conditions, where investigations of static and dynamic properties near critical points are to be carried out. It is

important to know how long a fluid system takes to approach closely enough thermodynamic equilibrium, and

what are the basic mechanisms that control the equilibrium process. The numerical computations above T_ are to be

compared with experiments. Simulations under microgravity conditions will be able to assess the permissible

temperature ramping rate in experimental data taking that will enable measurements of critical properties in a

quasi-equilibrium state. In the two-phase regime below T,, little is known about the equilibration dynamics and the

proposed experiments are expected to substantially help in understanding these processes.

I _i i I || | I | I I I i i i I I I |l _i I I I I I I | I I I II I II | II | I I I i I I I II t ! I _! | | i i II_ i!, t i ei i _! i, | _I | i I | I I I | i | ii I _i I _I I I | | ii, t | | i | | i i | I | |I _| __i | | i | 11 | | I, II | I I I I I I i | i | | _I | | _I |i | i i | | i i I II I _I | _i | _i | ! | | iI | i | | i I I I I I II ! _| I i i _t i I! I I I I I ! I I I I II I It eI i I II I |I I It eI I i | _| __I __i,,

ll-I 9 2
PROGRESSDURINGFY 1994:

There have been three main proiect,_ in this period:

A) Processing and analyzing temporal density evolution r data in 3He alter a programmed temperature step of the

cell. These data had been obtained throughout 1993.

B) Developing and improving the computer simulation program that calculates the spatial and temporal evolution

of thermodynamic coefficients of _He.

C) Writing a detailed paper describing both the experimental and the computed results lot _He above the critical

point, and also writing papers for Proceedings.

A) Data analysis. In the experiments that had lasted approximately 12 months, very systematic measurements of

the density equilibration were carried out both above and below the liquid vapor critical point (T,,, r,, P¢). During

this lengthy data taking, measurements were performed of the density evolution in time r(t) at two superposed

locations in a cylindrical cell after a programmed temperature step on the fluid container. This density evolution

towards equilibrium was automatically stored in a computer. Experiments were carried out "along several isochores,

one of them being the critical one. Also experiments were performed along several isotherms both above and below

the critical point below which both the liquid and the coexisting vapor phases could be sampled. Of this very large

_tmount of data, tho_ along the critical isochore and severn isotherms have been processed and displayed

graphically versus time. The superposed location of the two density sensors in the cell permitted the observation of

the density stratification in the cell, under the effect of the earth's gravity.

B) Computer strnulations. Together with the data analysis, the computer simulation of the temporal and spatial

evolution of temperature T(z,t), density r(z,t) and pressure P(z,t) has been significantly improved. This simulation,

which is restricted to the region above the critical point (single phase), uses the published static and dynamic

critical properties of 3He obtained in this laboratory, and calculates the equilibration of T, r and P following the

programmed temperature step of the fluid container. This is done for an arbitrary gravitational acceleration g. Hence

the computer simulation can yield results for the density evolution that can be directly compared with experiments

in a ground-based laboratory,, and it also predicts the evolution of the coefficients during an experiments under

microgravity conditions. Much effort was spent comparing experimental data and computations and the results can

be briefly summarized as follows: 1) There is an impressive agreement between the observed and predicted

amplitudes and shapes of the density evolution. In particular at temperatures well above the critical point, the

predicted sharp spike resulting from the adiabatic energy transfer ("piston effect") was clearly observed and the

predicted and observed amplitudes were in good agreement. The same good agreement was found for the amplitude

of the stratification. 2) However there is a systematic discrepancy in the time scales involved. While the observed

and predicted relaxation times agree far above T¢, there is a systematic departure as T_ is approached, whereby the

computed relaxation time diverges more strongly than the experimental one. Close enough to T_t the stratification

causes a leveling off of the relaxation time curve versus (T-T¢), both predicted and observed. Under microgravity

conditions, the computer simulation shows that the relaxation time continues diverging. 3) Furthermore

simulations in calculating the properties inside the fluid in the course of temperature ramping - both upwards and

downwards were conducted, which gave remarkable results. In particular the rms density variation thoughout the

fluid was predicted as a function of ramping rate and temperature.

C) Manuscripts. Several drafts of a long and detailed manuscript "Density equilibration near the Liquid-Vapor

critical point of a pure fluid: I Single phase T>T_" have been produced, and we hope that the final paper will be

ready for submission to Physical Review sometime by middle of November. A first draft of the sequel of this paper

II- coexisting phases T<T_ has been written.

I1-193
STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 1/94 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-07-20

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Zbong, F., and Meyer, H. Density equilibration near the liquid-vapor critical point of a pure fluid: [-single phase T>Tc.

Phys Rev B. (submitted).

Proceedings

Zhong, F., and H. Meyer. H. "Density equilibration near the liquid-vapor critical point in 3He." Fluid Mechanics

Phenomena in Microgravity, American Society of Mechanical Engineers.

Zhong, F., and Meyer, H. "Densisty equilibration near the liquid-vapor critical point in 3He." Proceedings of the

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Zhong. F,, and Meyer, H, "Numerical calculation of density equilibration above the 3He liquid-vapor criticat point."

Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Zhong, F. and Meyer, H. "Density equilibration for a pure fluid near Tc: Application to 3He." Proceedings of the 12th

Symposium on Thermophysical Properties.

iiiiiiiiI*IiiiiiIIiiiiIIiiiIIIiIiiiiIiiiiIiiIIIiiIIIiiiIIIiiiiiIIii iiiIIiIIiIIIiiiiiiiiIIIIiiiiiiiiiIIiIIIIIiiiiiIiiiiIIIII IIiiiiiIIIIiiiIi iiiiiIIIiiii iiiIIIiiiiii iiiIIIiiiiiIIiii iiiiiiiIiiiiiIIi iIiiiiiiiiIIIIiiIiiiiiII lliiiIill iii IiiiiiiIlIIII

II-1 9 4
Nonlinear Dynamics and Nucleation Kinetics in Near-Critical Liquids

PRINCIPALINVESTIGATOR:Prof. Alexander Z. Patashinski Northwestern University

CO-INVESTIGATORS:

M. Rather

V. Pines

Northwestern University

Case Western Reserve University

TASK OBJECTIVE:

This grant activity is an early definition study to establish the theoretical toundations of the nonlinear response to

strong perturbations in near critical fluids. This is a subset of a larger goal to develop an understanding of the many

nonequilibrium states of strongly interacting systems. Critical fluids are to provide the experimental and theoretical

model systems. This early definition work will be the basis for one or more future low gravity experiments.

TASK DESCRIPTION:

The Principal Investigator will work on a description of the non linear formation and relaxation of inhomogeneities

in liquid-vapor and binary mixtures near their critical points. The perturbations ti'om homogeneity may occur from

stable and unstable initial thermodynamic states. There is a need for the inhomogeneities to be large and long lived.

Renormalization group formalism will be used to describe the non-Gibbsian distribution functions of the critical

fluctuations. Three experiments have been suggested in the proposal. They are as follows:

1. Relaxation of large inhomogeneities to a one-phase final state.

2. Nucleation kinetics during the formation of a final two-phase state starting from an initial unstable state.

3. Nucleation kinetics and the influence of spinodal decomposition dynamics on domain nuclei in a state near the

spinodal line.

TASK SIGNIFICANCE:

This is fundamental research into the non linear understanding of nucleation phenomena. Its long term

technological value rests on application to nucleation phenomena in a myriad of common phenomena at small

space and time scales.

Broader fundamental knowledge of strongly interacting systems in non-equilibrium can open up new technologies.

Our lack of knowledge in this area limits our current technological imagination.

PROGRESSDURING FY 1994:

Since funding was initiated in June 1994, the investigators have quantitatively analyzed weak pertubations in the

linear regime to confirm their formalism yields and adiabatic last heat transfer. They are now advancing their efforts

to apply the formalism to the non linear heat transfer in the vicinity of a strongly pertubing hot body in a very

compressible critical fluid.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-24-05-07

RESPONSIBLECENTER: LeRC

II-195
lI. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

Precise Measurements of the Density and Thermal Expansion of 4He Near the Lambda Transition

PRINCIPALINVESTIGATOR: Dr. Donald M. Strayer Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

Dr. Talso Chui

Prof. Nai-Chang Yeh

Dr. Mark Lysek

Jet Propulsion Laboratory (JPL)

California Institute of Technology

Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

The objective of this ground-based Annual NRA project is to demonstrate the value of high-precision density

measurements in the study of the lambda transition of liquid helium. During the two years of Annual NRA

funding, we shall demonstrate the capability to perform high-precision density measurements using superconducting

cavities, applying high resolution thermometers (HRTs) tbr temperature control. We shall also demonstrate the

ability to deconvolve nonuniIormities caused by gravity from the density data.

TASK DESCRIPTION;

We shall employ superconducting microwave cavities having Q-values near 101°, operated in modes that have

standing wave patterns that are axially symmetric and whose z-dependences are well known. Upon filling the cavity

with liquid helium, and adjusting the temperature near to T, measurements of the cavity resonant frequency will

reflect the helium density. Very near the transition a normal-superfluid interface will form in the cavity: Moving

this interface across antinodes of the standing wave pattern by high resolution temperature control will allow the

density to be probed in the interfacial region. Measurements at many temperatures will provide d_nsity data for

deconvolving the temperature dependence of the density from the gravity-induced effects.

TaSK SIGNIFICANCE;

We expect that our earth-bound measurements will demonstrate the value of precision density measurements to

exploration of the lambda transition, and to study of cooperative transitions in general. The preliminary

measurements to be conducted in this Annual NRA task will provide use/ul information about future exploration of

related experiments to be conducted in the microgravity experiments. The results will lead to applications of the

technique to problems that include studies at many pressures, studies of nonequilibrium effects, or studies in

confined geometries.

PROGRESSDURING FY 1994:

This task has very recendy been provided with funds. Since that time, the design of a probe on which to perform

the demonstration measurements has progressed through development of a rudimentary thermal model, plus the

determination of required frequency resolution in the microwave components. Obtaining those microwave

components is now underway, with all major pieces in hand, and only some smaller pieces yet to be procured. As

stated in the proposal, an existing superconducting cavity and a cryoprobe already in Prof. Yeh's laboratory will be

modified Ibr use in these measurements. The thermal model will be improved, and then will be used to design the

modifications to yield the necessary thermal stability on the platform.

The postdoctoral fellow who will pertorm the measurements is identified, has participated in the design of the

microwave measurement system, and will be on board by the start of 1995.

11-196
II. MSAD Program Tasks -- Ground-based Research Discipline: Benchmark Science

.,,,ll*,,.,.i.q**n.l|*,n|,,,llnn|,llDn,,,i .n.,,,,i .I.*,,,,*,,*,,l,,.i.l,,,,,i.i.m.,HnHm|*t,jl,,l*,l*nl.l*,n,t *,,ll,,n.n.m.l,,, *'''J"V''',*ll**l'''H'''ll'V'J'n"n'n0*l'*''''l*H'n'*n"'''''llll'l" _n0n,Hl**_.n,.,.n

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 9194 EXPIRATION: ;_196

PROJECT IDENTIFICATION: 962-24-04-12

RESPONSIBLECENTER: JPL
Evaluation of Ovarian Tumor Ceil Growth and Gene Expression

PRINCIPAL INVESTIGATOR: Pro/'. Jeanne L. Becker. Ph.D. University of South Florida

CO-INVESTIGATORS:

G.F. Spaulding

R.H. Widen

NASA Johnson Space Center USC)

University of South Florida (Tampa Gen. Hospital)

TASK OBJECTIVE:

Examine growth and gene expression of LN1 ovarian tumor cells cultured in the Rotating-Wall Vessel (RWV).

TASK DESCRIPTION:

A model for the growth or"human ovarian tumor cells has been developed. This model allows for three-dimensional

growth of LN1 ovarian tumor cells, facilitating the generation of tissue-like aggregates of cells exhibiting complex

architecture. The cell populations generated during RWV culture morphologically and histochemically resemble

those characteristics exhibited by the original patient tumor specimen from which this cell line was developed.

TASK SIGNIFICANCE:

In vitro growth of human ovarian tumor cells is not readily accomplished using traditional culture methodologies.

Using the low shear, low turbulence conditions provided by the microgravity environment of the NASA RWV, we

have developed a model which supports the culture of these ceils under conditions that simulate in vivo-like growth.

We have used this model to study growth characteristics in conjunction with changing patterns of gene expression

and oncoprotein production occurring during complex cellular aggregate formation in vitro.

PROGRESSDURINGFY 1994:

During this year, my laboratory has received two rotating-wall vessels, a slow-turning lateral vessel (STLV) and a

high aspect rotating-wall vessel (HARV). We have become familiar with the care, set-up and operation of these

vessels in our hands and the growth of LN1 in these vessels. During culture in the RWV, LN1 cells become highly

metabolic, exhibiting greatly increased rates of glucose utilization during continued three-dimensional growth.

Because of the greater oxygenation capacity of the HARV, the growth of LN1 cells in the HARV is superior to

growth in the STLV. In conjunction with an increased rate of glucose utilization. LN1 also exhibits an increase in

the percentages of cells undergoing DNA synthesis (S phase of cell cycle) and mitosis (G2+M phases) with time in

HARV culture.

We have demonstrated that the LN1 cell line has the capacity to differentiate into multiple cell populations during

three-dimensional culture in the RWV. These populations have been characterized both immunocytochemically and

flow cytometrically. Recent studies have evaluated staining patterns of intermediate filaments and oncoproteins in

LN1 cells grown in the RWV, as compared to cells present in the original tumor specimen from which LN1 was

derived. Staining patterns for cytokeratin, vimentin and chondroitin sulfate present in LN1 grown

three-dimensionally in the HARV were remarkably similar to that observed in the original tumor, in contrast to

patterns observed in control Petri dish cultures and monolayer culture. LN1 cells grown in the HARV also

demonstrated increased staining for TAG-72 carcinoma antigen and c-erbB2 oncoprotein, as exhibited by the original

specimen.

LN1 cells in monolayer culture exhibit constitutive expression of mRNA and protein for c-erbB2, c-ras and mutant

p53. Analysis of LN1 grown three-dimensionally also revealed constitutive expression of mRNA for c-erbB2, c-ras

and mutant p53, although differential expression of the corresponding oncoproteins, p185 c_*_, p21 "'_', p21 °K_"

and mutant p53 protein, was observed within individual cell populations generated during RWV culture. Additional

studies have revealed that LN1 expression of TGF-beta is altered in RWV culture, relative to two-dimensional

growth in monolayer culture.

II-198
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 11/92 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-23-01-15

NASA CONTRACT NO.: NAG-648

RESPONSIBLE CENTER: JSC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Becker, J.L. Women's health issues and space based medical technologies. Earth Space Review, 3, 15-19 (1994).

Journal Becker, J.L. Microgravity model of ovarian tumor cell growth. Low G, 5, 12 (1994).

Presentations

Anderson. S.M., Becket, LL., Papenhausen, P.R. "Verification of an i(5p) marker chromosome in a mixed mullerian tumor

of the ovary by fluorescence in situ hybridization." Internatl. Conf. Immunogenet. 1994.

Becker. J.L., Goodwin, T.J., Prewett. T.L., and Spaulding, G.F. "Growth and gene expression in human ovarian cancer."

Workshop on Cell Culture Applications in Biotechnology, World Cong. Cell Tiss. Culture, 1994.

II-1 9 9
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

.nloll*ll.eoollollHin|lHIoHon.llollollluooo H tnaoluot.l|ol.na.l_ol:. IHI0_0|IgOl0|I0;10nl.;.I .n .m.Jlonlolllolloo||onl-Ilol_oollolo|l_lol-ln*Ho-.H|_ooonglolaollollolulaunlloouH|Honloleootl|ooloJloaloana|onollo|ou

Crystallographic Studies q{ Proteins Part 11

PRINCIPALINVESTIGATOR: Dr. Daniel C. Carter NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

J. Ho (X. He) NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

This research involves the atomic structure determination of several protein structures. Key areas of study involve

serum albumin structure and chemistry and HIV antibody complexes and structure. Aspects of this research generate

flight experiment problems and contribute to facilities for the evaluation of flight experiment activities.

TASK DESCRIPTION:

The overall goal of this research is to utilize ground-based and microgravity-grown protein crystals to improve our

understanding in two important areas of structural molecular biology. The lirst involves the determination of the

definitive structure of serum albumin together with the chemical basis for the molecules' tremendous ability to bind

and transport an immense variety of ligands throughout the circulatory system. The second area which is also broad

in scope involves the structure determination of a series of human monoclonal antibodies expressed against the

AIDS virus together with their respective antigen complexes. Both of these project areas are in an advanced stage

where improvements in crystal quality will have significant impact on our understanding of the underlying

chemistry.

Screens for optimum crystallization conditions or to determine crystallization conditions for new proteins will be

conducted by the hanging-drop vapor-diffusion method. A Micromedics robotic crystal growth system is available

to aid systematic surveys of pH, precipitant type, precipitant concentration, and protein concentration. The

monoclonal antibodies expressed against the AIDS virus will be supplied by collaborator Professor Forian RLicker

of The Institute of Applied Microbiology in Vienna, Austrm. Cleavage of the antibody with papain or pepsin to

produce the Fab fragments and subsequent purification will continue to be conducted. Antigenic peptides will be

provided by Dr. RtJcker and/or as a gilt from IAF Biochemicals of Canada. X-ray diffraction data will be collected

from both ground-based and flight crystals using a'multi-wire area detector (Nicolet) and an imaging plate system

(R-Axis) mounted on a Rigaku RU200 rotating anode generator. In favorable cases whero'the logistics can be

arranged, diffraction data will be collected at synchrotron sources.

TASK SIGNIFICANCE:

High quality, single crystals are of tremendous value for a variety of industrial and research applk_ations. Crystals

of sufficient size and quality also provide invaluable avenues to understanding the detailed atomic structure and

function of biological macromolecules and other substances. Efforts to produce higher quality protein crystals for

application in x-ray crystallography have spawned numerous experimental approaches which range from the

application of automated screening to the growth of protein crystals in microgravity.

PROGRESSDURINGFY 1994:

The structure of Schistosomajaponica glutathione-S-transferase fusion protein was determined. This structure has

several important implications:

1. The protein contains the principal portion of an epitope of gp41 of the human immunodeficiency virus type 1

which is recognized by a neutralizing antibody, 2F5.

2. The protein is from a parasitic flatworm which is the causative agent of schistosomiasis, the second leading cause

of death and suffering in the world (malaria is primary). According to the scientific literature, this protein was a

leading candidate for the development of a vaccine against this disease.

Ill-200
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

Illllllllt;lll.ll|;lllllllllHIIglllll|ljlllllllljlllll.ll.llt BllllllUlll_l;.Ig0_.l;HIIIIIIlllM.10ea.H01111.1.;.101111t|alllllllt .IJ|ll.01111.I.II0|lU_Umllll01;.0._l HI HH_I H IIHIIWlIH H IIHII011|III0t|_II.I|III_;101H_

3. The protein is part of an important commercial protein expression system. We have proposed that fusing

proteins which have proven difficult to crystallize to GST may provide a new and expeditious route to their structure

determination. Verification is in progress.

The refinement of several structures is neanng completion. Cytochrome c5 from Azotobacter vinlandii has been

refined to 1.9 angstroms resolution. HEW lysozyme grown in microgravity is refined to previously unreported high

resolution. Additional high quality flight crystals are required to finish this work. A new myoglobin structure is

solved and in the final stages of refinement. The nature of long-chain fatty acid binding to albumin was determined.

Several new and important proteins have been crystallized. Several manuscripts are in preparation.

Also, this year an authoritative review on the structure of albumin was published by Academic Press.

We completed the first year of two government/industry cooperative agreements. Both are interested in extending

and/or expanding the agreements. Three additional agreements are under consideration.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-23-08-17

NASA CONTRACT NO.: In-hou_

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Carter. D.C., and Ho. J.X. Structure of albumin. Advances in Protein Chemistry. vol. 45. 153-203 (1994).
II. MSADProgram Tasks _ Ground-based Research Discipline: Biotechnology

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Microgravity Studies of Ceil-Polymer Cartilage Implants

PRINCIPAL INVESTIGATOR: Dr. Lisa E. Freed Massachusetts Institute of Technology (MIT)

CO-INVESTIGATORS:

R. Langer

G.F. Spaulding

T.J. Goodwin

D. Ingber

Massachusetts Institute of Technology (MIT)

NASA Johnson Space Center (JSC)

NASA Johnson Space Center (JSC)

Harvard University

TASK OBJECTIVE:

The long-term objectives of our current studies are: (1) to assess the effects of in vitro culture conditions,

microgravity in particular, on tissue morphogenesis, (2) to correlate the characteristics of engineered tissues with

bioreactor fluid dynamics in the torm of physically and biologically sound mathematical models, and (3) to elucidate

the mechanisms underlying the effects of microgravity on the structure and function of the engineered tissues.

Related practical objectives are to optimize bioreactor design and develop operating strategies for cultivating tissues

under conditions of simulated and actual microgravity.

TASK DESCRIPTION:

A simulated microgravity environment can be used to engineer cell-polymer tissue constructs, the size and shape of

which are determined by an FDA approved, biocompatible, biodegradable scatfold with a defined three dimensional

(3D) shape and structure. In particular, fibrous polyglycolic acid (PGA) can be seeded with isolated cells

(chondrocytes) and cultivated in rotating bioreactors to make cartilaginous tissue constructs for in vitro studies of

tissue morphogenesis and/or in vivo implantation.

TASK SIGNIFICANCE;

Engineering cartilage (i.e., tissue constructs grown in vitro using isolated cells and biomaterial scatfolds) can be

used in vivo, to create subcutaneous neocartilage (in nude mice) and for joint resurfacing (in rabbits), and thus

represents a biologically based therapy for repairing cartilage damaged by congenital defects, arthritis, or trauma.

We have shown that the structure of engineered cartilage depends on hydrodynarmc forces during in vitro cultivation;

this is similar to the known effects of environmental forces on the tissue morphogenesis in vivo. For example,

structural organization of bone and cartilage depends on the mechanical distribution of compressive and tensile

stresses. Ground-based research utilizing rotating vessels (simulated microgravity) is expected to enhance our

understanding the principles governing tissue morphogenesis. Space studies (actual microgravity) can further extend

the operating limits of these vessels. The same approaches and methodologies can also be applied to other

cell-polymer model systems, in order to engineer other clinically useful tissues.

PROGRESSDURINGFY 1994:

Specific Aim (1):

Establish methods to culture chondrocytes in 3D synthetic, biodegradable polymer scat'folds in a rotating vessel to

regenerate cartilaginous tissue.

Chondrocytes were unitormly seeded and cultivated on polymer scaffolds in two rotating vessels, the Slow Turning

Later'a/Vessel and the High Aspect Ratio Vessel (STLV, HARV). One week cell-polymer constructs grown in

rotating vessels contained more GAG (total and per gram) and did not have fibrous outer capsules, as compared to

control constructs grown in a previously established spinner flask system. These findings can be attributed to

effects of bioreactor fluid dynamics, and indicate that differentiated cell function is promoted under conditions of

simulated microgravity. As compared to natural bovine articular cartilage, 1 week cell-polymer constructs had three

times more cells, 75% as much GAG, and 10% as much collagen per gram dry weight

_in_oiaoDoooo_I_ooooo_aI_I_a_iu_1ajfa1u_uona=nuoi_ooaoIaooaol6I_Iua_awa_aI_u1_ooao_ao_aonao_aouaoiao_Iu_oo_ou_oa_o_Io_Ig_ooaioaan_n_on_o_iuQoooonao_aouuou1oI_oo_o_o_ooonaojoo_oooooonaon_ootaoooooo_oaIaaiioonaonaI_ooo_ouo_ooo_oo_oooou_

11-202
Specific Aim (2):

Amplify chondrocytes isolated from small cartilage biopsy specimens to obtain the cell mass required to seed

clinically sized polymer sc_folds.

Cells can be amplified using petri dishes (serially passaged monolayers) or bioreactors (cell spheroids), but these

processes can be associated with loss of differentiated cell function (e.g., secretion of type I instead of type II

collagen). We are developing an ELISA to quantitate the type the collagen extracted from chondrocytes after

amplification, in order to assess whether rotating vessels can be effectively used for cell amplification.

Specific Aim (3):

Correlate the characteristics of engineered tissues with specific fluid dynamic parameters in order to optimize

bioreactor operating conditions.

Rotating bioreactors represent a model system for in vitro tissue engineering because hydrodynamic forces can be

quantitated and controlled. Viscous coupling induces a steady fluid flow field which entrains inoculated cells,

suspends polymer scaffolds, and maintains nascent cell-polymer constructs in a state of continual free-fall. Under

these conditions, the relative velocity between the construct and the surrounding fluid can be determined (both

numerically and experimentally), used to calculate acting hydrodynamic forces and stresses, and correlated with the

biochemical and physical properties of the engineered tissue. In pilot studies, a relative construct-fluid velocity of

2-3 cm/sec and an average hydrodynamic stress of 1.5 dyn/cm: promoted chondrocytes to attach to polymer scaftolds

and regenerate cartilaginous tissue.

Collaborations:

1) Extension from chondrocytes to other cell types: Our group at M.I.T. is now working with Dr. Hartzell at

duPont to culture cardiac myocytes on PGA scaffolds in rotating vessels. In the pilot study, cell-polymer constructs

Ion]ned that contracted spontaneously and synchronously at rates of 30-130 beats per min.; such constructs could

potentially be used for in vitro physiological and pharmacological studies. We also plan to collaborate with Dr.

Lelkes at the University of Wisconsin to use other cell types in a similar model system. Optimal culture

conditions are expected to depend on the cell type, with respect to mass transfer requirements and shear sensitivity,

and on the desired clinical application, with respect to tissue dimensions, structure and function.

2) Extension from simulated to actual microgravity: Flight studies could potentially be done relatively soon using

existing NASA hardware, as the t_st space studies have already been done in parallel to the ongoing ground-based

research. Bovine chondrocytes obtained from M.I.T. were flown aboard STS-62 (February, 1994) in an experiment

done at the Johnson Space Center. In briet, chondrocytes plated tissue culture dishes were flown in the

Biotechnology Specimen Temperature Controller (BSTC) and the cells were cultivated at 37°C/'or various time

intervals (1-4 days). These pilot studies demonstrated chondrocyte growth and metabolism under conditions of

actual microgravity.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 1

MS Students: 0

PhD Students: 0

TASK INITIATION: 3/94 EXPIRATION: 3/95

PROJECT IDENTIFICATION: 962-23-01-11

NASA CONTRACT NO.: NAG-9655

RESPONSIBLECENTER: JSC

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11-203
|I. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

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BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Freed, L.E. Grande. D.A. Lingbin, Z. Emmanual. J. Marquis LC. Langer. R. Joint resurfacing using allograft chondrocytes

and synthetic biodegradable polymer scaffolds. J. Biomed. Mater. Res., 28, 891-899 (1994).

Freed, L.E. Marquis, J.C. Vanjak, G. Emmanual, J. Langer, R. Composition of cell-polymer cartilage implants. Biotech.

Biocng., 43, 605-614 (1994).

Freed, L.E. Vanjak, G. Biron. RJ.,Eagles, D. Lesnoy, D. Barlow. S.K. Langer R. Biogradable scaffolds for tissue

engineering. Bio/Technology, 12, 689-693 (1994).

Freed, L.E. Vanjak-Novakovic. G. Marquis, J.C. Langer, R. Kinetics of chondrocyte growth in cell-polymer implants.

Biotech. Bioeng., 43, 597-604 (1994).

Freed, L.E. Vunjak-Novakovic. G. "Tissue engineering of cartilage". In: Brozino, J.D. (ed). The Biomedical Engineering

Handbook, CRC Press., (In press 1994).

Freed, L.E. Vunjak-Novakovic, G. Microgravity Tissue Engineering. In Vitro Cell. Dev. Biol., (Submitted 8/94).

Freed, L.E. Vunjak-Novakovic. G. Cultivation of cell-polymer tmptants in bioreactors. In: J.B. Griffiths. A. Doyle, D.G.

Newell (eds). Cell and Tissue Culture Laboratory Procedures. Wiley & Sons (invited chapter), (September 1994).

Freed, L.E. Vunjak-Novakovic, G. Cultivation of cell-polymer constructs in simulated microgravity. Biotech. Bioeng.,

(Submitted August 1994).

Presentations

Freed, L.E.,Vunjak-Novakoic. G. Blum. J.K. Emmanual, J.

Association, Durham, NC (June 1994).

"Effects of shear on in vitro chondrogenesis." Tissue Culture

Freed, L.E.,Vunjak-Novakovic. G. "Chondrocytes cultured on biodegradable polymers form neocartilage in vitro and in

vivo." European Society for Osteoarthrology, Bari. Italy (September 19941.

Freed, L.E. Vuniak-Novakovic. G. "Tissue engineered cartilage: bioreactor cultivation and in vivo implantation."

Biomedical Engineenng Society, Tempe, AZ (October 1994).

Freed, L.E. Vunjak-Novakovic, G. Grande, D.A. Emmanual, J. Langer, R. "Cell-Polymer Cartilage hnplants." Keystone

Tissue Engineering Conference. Taos, NM (February 1994).

Vuniak-Novakovic, G. Freed. L.E. "Hydrodynamic forces determine in vitro chondrogenesis in a three-dimensional

cell-polymer model system." European Society for Osteoarthrology, Bail, Italy (September 19941.

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II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

_"_u_|_n_m_o_a_i_|_B_I_"_"_r_I_i_i_i_o_'_|_|_ JQit,,l,Ul,_lll|l,0110,1 J.IID,_,0,10HI¢,I41,,¢,IIII¢IIIIHIHIII,II¢IIm.I|t,I,H.Hm|II.U mmllll_lm||

Excitable Cells and Growth Factors under Microgravity Conditions

PRINCIPAL INVESTIGATOR: Dr. Charles R. Hanzell Alfl'ed I. duPont lnstitum

Co-INVESTIGATORS:

N. Schroedl

S. Gonda

Al#ed I. duPont Institute

NASA Johnson Space Center (JSC)

TASK OBJECTIVE:

Peptide growth factors are intimately involved in the regulation of normal muscle growth and differentiation.

Invaluable ground work has been laid by investigators using numerous muscle cell lines to elucidate the

contributions made by these growth factors in myogenesis, and significant advances in understanding these

mechanistic pathways have been achieved. We underscore, however, the importance of conl-trming these results in

primary muscle cultures.

TASK DESCRIPTION:

Using the NASA bioreactor, we will examine the etfects of a three-dimensional architecture on the growth and

differentiation of neonatal rat heart cells and young adult muscle satellite ceils. The bioreactor allows muscle cells

to orient and grow within constraints normally determined by the basal lamina in vivo, yet permits experimental

parameters to be cleanly delineated. Once muscle cultures are established, the role of neuromuscular junction

formation on myogenesis will be explored by co-culture of heart or skeletal muscle cells with cholinergic neurons.

Alterations in the differentiation program induced by fibroblast growth factor, insulin-like growth factor-I and

transforming growth factor-b will be ev',duated.

TASK SIGNIFICANCE:

The two-dimensional, unit-gravity constraints of conventional cell culture do not opttmally model the

three-dimensional cytoarchitectural design of the in vivo system. Ltmitations inherent in standard cell culture

systems encourage us to continue the development of an innovative in vitro model system that is not limited by

gravity-induced constraints and that promotes the formation of three-dimensional, in vivo-like tissue that is critical

Io understanding myogenic regulation.

PROGRESS DURINGFY 1994:

1. Neonatal Rat Heart Cells Cultured in HARV Bioreactor

h_ vitro characteristics of cardiac cells cultured in simulated microgravity are reported. Tissue culture methods

performed at unit gravity constrain andiorage-dependent cells to propagate, differentiate, and interact in a

two-dimensional (2D) plane. Neonatal rat cardiac cells in 2D culture organize predominantly as bundles of

cardiomyocytes with the intervening areas filled by non-myocyte cell types. Such cardiac cell cultures respond

predictably to the addition of exogenous compounds, and in many ways, they represent an excellent in vitro model

system. The gravity-induced 2D organization of the cells, however, does not accurately reflect the distribution of

cells in the intact heart tissue. The NASA designed High-Aspect-Ratio-Vessel (HARV) bioreactors provide a low

shear environment which allows cells to be cultured in static suspension. To evaluate the potential changes induced

by the culture conditions of the HARV, neonatal rat heart cells are currently being characterized by a combination of

biochemical and cell biological techniques. Since, at the preliminary level, the coordinated activity of the heart

depends on specific, sequential events (including cytosolic Ca 2. elevation, conformational changes and interactions

among the contractile proteins, energy availability, and the alignment of myocytes and organization of cellular

structures), we are in the process of examining: 1) Contractile Function: cardiac cell beat frequency and strength; 2)

Ca 2÷Handling: Ca 2. distribution, mobilization, and sequestration; 3) Protein Composition: the expression of

essential proteins; 4) Energy Metabolism: shifts in metabolism or ATP availability; 5) Cellular Morphology: the

11-205
II. MSADProgramTasks -- Ground-based Research Discipline: Biotechnology

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spatial distribution of cardiac cell types; 6) Ultrastructural Morphology: the organization of cellular components and

organelles. HARV-3D cultures were prepared on microcamer beads and compared to control-2D cultures using a

combination of microscopic and biochemical techniques. Both systems were uniformly inoculated at lxl06 cells per

milliliter medium per 4.8cm 2 surface area (polystyrene). The serum-tree defined medium was exchanged at standard

48 hr intervals after day one in culture. Cells in control culture dishes adhered to the polystyrene surface of the

tissue culture dishes and exhibited typical 2D organization. Cells cultured in HARVs adhered to the Nunc D-Si

polystyrene microcamer beads, the beads aggregated into defined clusters containing 8 to 15 beads per cluster, and

the clusters exhibited distinct 3D layers: myocytes and fibroblasts appeared attached to the surfaces of the beads and

were overlaid by an outer cell type. In addition, cultures prepared in HARVs using alternative support matrices also

displayed morphological formations not seen in control cultures. Generally, the cells prepared in HARV and control

cultures were similar; however, the dramatic alterations in 3D organization gives credence to the generation of

tissue-like organizations of cardiac cells in simulated microgravity.

2. Rat Skeletal Muscle Satellite Cells Cultured in the HARV Bioreactor

Satellite cells are posmatal myoblasts responsible for providing additional nuclei to growing or regenerating muscle

cells. Satellite cells retain the capacity to proliferate and differentiate in vitro and, therefore, provide a useful model

to study postnatal muscle development. Limiting proliferation and differentiation of satellite cells in 2-D could

potentially limit cell-cell contacts important for developing the level of organization in skeletal muscle obtained in

vivo. Culturing satellite cells on microcarrier beads suspended in the High-Aspect-Ratio-Vessel (HARV) designed

by NASA provided a low sheer, three-dimensional (3-D) environment to study muscle development. Primary

cultures established from anterior tibialis muscles of growing rats (~ 200 gm) were used for all studies and were

composed of greater than 75% satellite cells. Different inoculation densities ranging from 0.Sx106 to 2x106 cells

with a cell/bead ratio 20:1 did not affect the proliferation potential of satellite cells in the HARV. Plating

efficiency, proliferation, and gluco_ utilization were determined and compared between 2-D flat culture and 3-D

HARV culture. Plating efficiency (cells attached + cells plated x 100) was similar between the two culture systems

and generally was greater than 70%. Proliferation was reduced in 30% of HARV cultures and this reduction was

apparent for both satellite cells and non-satellite cells. Furthermore, reduction in proliferation within the HARV

could not be attributed to reduced substrate availability since glucose levels in media from HARV and 2-D cell

culture were measured to be similar. Morphologically, microcamer beads witl_n the HARVs were joined together

by cells into three-dimensional aggregates composed on 10-15 beads/aggregate. Aggregation of beads did not occur

in the absence of cells. Myotubes were often seen on individual beads or spanning the surface of two beads. In

summary, proliferation and differentiation of satellite cells on microcarrier beads within the HARV bioreactor results

in the formation of a three-dimensional level of organization that provides a suitable model to study postnatal

muscle development.

3. Myogenic Gene Expression During Postnatal Myogenesis

Rat skeletal satellite cells (postnatal myoblasts) express an intrinsic genetic program that defines them as belonging

to the myogenic lineage. This intrinsic program is best exemplified by the ability of satellite cells to differentiate

and form contraction-competent myotubes in vitro. MyoD, myogenin, MRF4 and myf5 represent a class of

muscle-specific transcription factors that modulate the myogenic program during embryonic development, but their

role during postnatal myogenesis remains unclear. We have determined the expression pattern for each myogenic

factor, and quantitated the level of each factor during different stages of postnatal myogenesis using satellite cells

isolated from young adult rats. Reverse transcription polymerase chain reaction (RT-PCR) was used to determine if

mRNA for each myogenic factor was present, cDNAs generated by RT-PCR were subcloned and used as specific

probes to quantitate the level of each myogenic factor. The following stages of myogenesis were characterized:

freshly isolated cells prior to plating (time 0); proliferation (3 day post-plating); day 1 of myotube formation (5 day

post-plating), early myotubes (8 day post-plating); late myotubes (13 day post-plating). All myogenic factors were

present at each stage examined using RT-PCR. However, levels for each myogenic factor mRNA differed. MyoD

level was highest in mononucleated cells. The myogenin level increased 15 fold between day 3 and day 5. MRF4

and myf5 were not detectable until day 1 of myotube formation (using slot blots). In summary, satellite cells

isolated from growing rats expressed myogenic factors in a different pattern than what has been reported for

embryonic myoblasts and established cell lines.

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11-206
STUDENTS FUNDED UNDER RESEARCH: TASKINITIATION: 11/92 EXPIRATION:10/96

PROJECTIDENTIFICATION:962-23-01-07

NASA CONTRACTNo.: NAG--656

RESPONSIBLECENTER: JSC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Akins. R.E. Schroedl, N.A. Gonda, S.R. and Hartzell. C.R.

Vitro Cell Diff., (Submitted 8/94L

Neonatal rat heart cells cultured in simulated microgravity. In

Ho, M.L.. Molnar, G. Funanage, V.L. Schroedl, N.A. Expression and quantitation of myogenic factors during postnatal

myogenesis. Dev. Biol., (Submitted 9/94).

Holshek, J.G. and Akins, R,E. Acetonitrile: A superior dehydrating agent in cellular preparations for SEM. Microscopy

Research and Techniques, (Submitted 7/94).

Holshek. J.G. and Akins. R.E Acetronitrile is hetter than ethanol as a dehydrating agent for cells prepared for SEM. Proc.

Micros. Soc. Amer., 52. 324-325 (19941.

Molnar, G. SchroedL N.A. Gonda, S.R. and Hartzell. C.R. Skeletal muscle satellite cells cultured in simulated

microgravity. In Vitro Cell. Diff.. (Submitted 8/94).

Presentations

Akins, R.E. "Neonatal rat heart cells cultured in simulated microgravity." Gordon Research Conference: Gravitational

Effects on Living Systems. August 1994.

Akins, R.E,, SchroedI, N.A. Gonda. S.R. and Hartze[l, C.R. "Characterization of a novel three-dimensional culture system

for cardiac cells." Mol. Biol. Cell., ,_xnerican Society for Cell Biology's 34th Annual Meeting, San Francisco, CA,

December 1994.

Ho, M.L., Molnar, G. Funanage, V.L. and Schroedl. N.A. "Myogenic gene expression during postnatal myogenesis."

Mol. Biol. Cell., American Society for Cell Biology's 34th Annual Meeting, San Francisco, CA. December 1994.

Molnar. G., Schroedl, N.A. Gonda, S.R. and Hartzell. C.R. "Characterization of postnatal myogenesis in a

three-dimensional system." Mil. Biol. Cell, American Society for Cell Biology's 35th Annual Meeting, San Francisco,

CA, December 1994.

Schroedl, N.A., Akins, R.E. Molnar, G. Gonda, S.R and Hartzell, C.R. "Culture of cardiac and muscle cells in simulated

gravity, In Vitro Cell Diff,, in press: (1994)." Society for In Vitro Biology's Annual Meeting, Research Triangle, NC,

June 1994.

11-207
Sensitized Lymphocytes for Tumor Therapy Grown in Microgravity

PRINCIPALINVESTIGATOR:Dr. Marylou Ingrain Huntington Medical Research Institutes

CO-INVESTIGATORS:

G. Techy HMRI

R. Saroufeem HMRI

S. Narayan HMRI

O. Yazan HMRI

T. Goodwin NASA Johnson Space Center

TASK OBJECTIVE:

The NASA High Aspect Ratio Vessel (HARV) bioreactor is used to generate spheroids of human tumor cells,

These spheroids are then used to sensitize the patient's lymphocytes to the patient's own tumor. The population of

tumor-sensitized lymphocytes (TSL) is then expanded in culture in the presence of interleukin-2 (IL-2) and used in

immunotherapy of the patient.

TASK DESCRIPTION:

This is a small scale, in depth pilot study in which nonspecifically stimulated autologous lymphocytes (ASL) and

tumor-sensitized lymphocytes (TSL) are administered serially by intxalesional injection as local immunotherapy of

invasive carcinoma of the urinary bladder. This is a modification of cellular immunotherapy that we have applied

with encouraging results in clinical trials to treat recurrent malignant gliomas (1). For the bladder cancer, the

urological surgeon will inject ceils intralesionally at intervals of approximately three weeks. Response to therapy

will be determined by direct observation of the lesions, serial biopsies for histological and cytological studies,

clinical evaluations and radiological exams. The ability to biopsy lesions at various times after injection of

sttmulated immune cells is an important advantage in understanding response to therapy and in refining the therapy.

Serial evaluation of lesions by histology, measuring the expression of major oncogenes and tumor suppressor

genes, assays of cytotoxic effectiveness of ASL and TSL to tumor obtained from urine specimens or bladder

wztshings can provide additional information between biopsy specimens. The pilot study provides an excellent

opportunity to evaluate the NASA HARV bioreactor as a method for culturing tumors as spheroids as contrasted

with conventional monolayer cultures. Tumor spheroids in vitro have a number of characteristics present in vivo

but absent from monolayer cell cultures. These characteristics, some of which will undoubtedly be important in the

generation of TSL cells, include the presence of specific tumor markers, angiogenesis and growth factors, biological

response modifiers, gap junctions and tumor suppressor gene expression. Changes in the level of expression and

distribution of intermediate filaments and the extracellular matrix elements have also been observed.

TASK SIGNIFICANCE:

Cancer of the unnary bladder is of special interest in immunotherapy because it has already been shown that

immunotherapy in the form of BeG treatment is efficacious. It is now widely used in clinical management of

invasive bladder cancer. Thus, there is sound evidence that appropriate mobilization of the patient's own cellular

immune mechanisms can have therapeutic efficacy. A number of investigators have recognized the possibility that

TSL may offer significant advantages in adoptive immunotherapy and there has been a recent resurgence of interest

in this approach (2). TSL can be expected to show increased tumor cell killing, as do tumor-infiltrating

lymphocytes (TIL) and they also hold forth the promise of serving as probes for identifying immunogenic gene

products in the tumor.

Many elderly patients with multiple tumors of the urinary bladder cannot tolerate extensive surgery or extensive

chemotherapy and may either have tailed to respond to BeG immunotherapy or are too unwell to tolerate side

effects of that therapy. These patients present a frustrating therapeutic problem to the urologist. We believe that

11-208
H.MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

local immunotherapy would be well tolerated by these patients and that it is a rational therapeutic strategy,. A

clinical trial of this therapy will also provide valuable information about how stimulated immune cells select and

identify their target cells, migrate through tissue, whether or not they continue to proliferate after injection and

other important considerations that will advance our understanding of cellular immunotherapy and aid in refining it

for treatment of bladder cancer and ultimately other cancers.

Bladder cancer has many advantages as a model/or refining methodology. It pemuts serial administration of

inununologically stimulated cells into the bladder lesions and yields serial biopsy specimens in which the

interactions of immune cells and their tumor targets can be studied directly.

1) Ingrain, M., Buckwalter. J.G., Jacques, D.G., et at. Neurological Research 12:265-273 11990)

2) Greenberg, P.D., Riddell. S.R.J.. Natl. Cancer Inst. 84:1059-61 11992)

PROGRESS DURINGFY 1994:

During FY 94 we have had considerable success in culturing a variety of otherwise "anchorage-dependent" cells lines

under conditions of simulated microgravity in the NASA HARV (high aspect ratio vessel) bioreactor. These cells

include relatively early passages os some cell lines. To avoid anchorage effects, no microcarrier beack,_are used. The

bioreactor is simply filled with a monodisperse suspension contmning 1-2 million cells per ml of nutrient medium.

The cultures are maintained lor periods of a few days to approxtmately a month. The spheroids produced are fixed in

Carnoy's/Bouin's fixative, then sectioned and stained. Some sections of each specimen are suuned with

hematoxyline and eosin and other sections from the same specimen are stained immunohistochemically to

demonstrate various markers of interest.

When cultured in the bioreactor, each cell line produces spheroids that demonstrate cell line-specific microscopic

architecture. Thus, gliomas tend to form small, compact spheroids that sometimes fuse to form larger bodies; the

PC3 cell line that was developed from prostate carcinoma metatstatic in bone forms discrete spheroids in which cells

are very loosely associated. Another prostatic carcinoma cell line, LNC',ff', typically forms elongated tubule-line or

folded structures. The bladder carcinoma cell line, HBL2, recently developed here, shows a definite tendency towards

epithelial differentiation. The tendency for the HBL2 cells to assemble in such a pattern suggests that various

adhesion molecules play a role in determining spheroid morphology, lmmunohistochemical staining to demonstrate

fibronectin, collagen, vimentin, CD44 and other cell adhesion molecules can be expected to provide further insight

into spheroid formation and differentiation. These studies are in progress.

An abstract and poster describing results of cell culture in the NASA bioreactor were accepted for presentation m the

"Hot Topic" poster session at the Congress on Cell and Tissue Culture Regulation, Cell and Tissue Differentiation

convened by the Tissue Culture Association, June 4-7, 1994 at Research Triangle Park, N.C. Dr. 'Rarnez

Saroufeem, who had primary responsibility for the bioreactor cultures of the HBL2 cancer cell line, attended the

meeting and presented the poster.

Our clinical collaborator, Dr. Michael Bishai, urological surgeon, has provided fifteen surgical specmaens of bladder

tumors and these have been invaluable. They have allowed us to reline tissue culture methods specifically for

bladder cancer. Most of the patients from whom the specimens were obtained did not meet protocol requirements

(patient selection criteria) for the immunotherapy trial and Dr. Bishai managed these patients clinically using other

therapeutic modalities. The fifteenth patient does meet protocol requirements and has just been entered as the lhst

protocol patient.

From the bladder cancer spectmens obtained so far, we have established one bladder cancer cell line and, at lea.st one

addition',d specimen may also yield a permanent cell line. The new cell line, designated HBL2, has been cultured in

both monolayer culture and in the NASA bioreactor culture vessel HBL2 cells, as well as minced tumor from some

of the other bladder cancers and glioma and prostate cancer cell lines, provide important experimental and reference

specimens for immunohistochemical demonstration of "markers" of interest and for comparison of "marker"

expression in cells grown in monolayer as contrasted with the same cell lines grown as spheroids or examined in

11-209
tumor mice spectmens. Although we cannot, of course, expect to establish a permanent cell line (i.e., at least 25

passages) from every tumor, primary cultures and tumor mince will be available tOT use in preparing TSL in all

cases. Where possible, lymphocytes to be tumor-sensitized for bladder cancer immunotherapy will be exposed to

tumor mince, monolayer cultures, and tumor spheroids in par_lel so that we may compare the relative

immunological effectiveness of the three modes of tumor presentation. We also hope to establish, from a least one

tumor, a line of fibroblasts and a line of endothelial cells as well as tumor cells and to use these autologous cells in

a structured series of co-cultures to observe histogenesis and the effects of active histogenesis on the expression of

antigenic gene products.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 11/92 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-23-01-14

NASA CONTRACT NO.: NAG-649

RESPONSIBLE CENTER: JSC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Ingrain, M., Techy, G.B.. Narayan. S.. Sarouteem, R,, BishaL M., Spaulding, G.F. and Goodwin. T.J. Epithelial

differentiation of early passage human bladder cancer ceils in simulated microgravity of the NASA HARV bioreactor, (h_

preparationL

Ingrain, M., Techym, G.B.. Narayan, S., Saroufeen, R., Spaulding, G.F.. and Goodwin, T3. Variable three-dimensional

growth of human malignant tumors in simulated microgravity of the NASA HARV bioreactor. (In preparationl.

Presentations

Saroufeem, R., Ingrain, M., Techy. G.B., Narayan, S., Bishai, M.. Craft. J.. Spaulding, G.. and Goodwin. T.

"Three-dimensional growth and differentiation of early passages of human tumor cells in simulated microgravity in NASA

bioreactor." Annual Meeting of the Tissue Culture Association, June 4-7, 1994 at Research Triangle Park. Abstract

SV-1006, Hot Topics Addendum Booklet.
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

Three-Dimensional Modeling qf Human Colon Tissues

PRINCIPALINVESTIGATOR:Dr. J. M. Jcssup New England Deaconess Hospital

CO-INVESTIGATORS:

P. Thomas Harvard Medical School, Deaconess Hospital

TASK OBJECTIVE:

The objectives of this project are to determine whedmr 1) microgravity permit,,; unique, three-dimensional cultures

of neoplastic human colon tissue and 2) this culture interaction produces novel intestinal growth and differentiation

factors.

TASK DESCRIPTION:

The thitial phase of this project wilt test the feasihility el microgr:tviD' for tile cnlm, ation and differentiation of

human cohm carcinoma. We propose to do this in rota_ing xvail _c_sel._ (RWVs) which pr_,ide a low shear stress

enviromnent in unit graviLv. Ill this environment, early experiments have demonstrated nonnai hunlan COIoII

fibroblasLs stimulate tile differenuati¢m of certain human colorl carcin()t_la ceil lmcs _:_,lhal they produce

three-dimensional tissue ma,sses that are similar to neoplasms m patients _r in xcnogralts in athvmic nude mice.

TASK SIGNIFICANCE:

The important question is whether this differentiation induced by t_b[obla.qs _sduc tt_ the low shear stress

environment of the RWV or whether suspension culIurcs ill the R\VV,, are silllilLu Io cultures m stalld;trd culture

systems in unit gravity. Should the low shear stress envmmnlent _1 the RWV hc supeno_ to that el conventional

culture systems, then the co-culture experiments should he attempted m an actu_tl mlcrogravi_y environment.

PROGRESSDURINGFY 1994:

This grant was completed in May 1994, _md it_ purpose W:L_tO determine whcdlcr n_nnal ._m_rnal cells coated with

epithelial ceils would form three-dimensi_mal structures that were similar to tissues th:.tt deveMped in mice or

humans. We studied adenocarcinomas of the colon _md heg_m studies wilh lloFInal colOlilC epHhelium. \Ve did not

culture norm',d colonic epithelium in the rotating wall vessel (RWV _because v,,ewere not able to ob_iin a small

(50ml) RWV. Nonetheless, we did demonstrate that normal cohmic epithelial cells isolated from colonic cwpts

adhered to collagen Type IV and to carcinoembryonic anUgen (CEA)-coatcd surlaces. This suggests that CEA is an

intercellular adhesion molecule that may be used by human norm_d colonic epithelial cells, while nonna.l

colonocytes use collagen Type IV as a ligand m their basement membrane. This work resulted in a publication in

Gastroenterotofly. As indicated in thai publication, normal c_,qonocvles tie nol survive more them 24-48 hours when

cultured on either CEA or collagen Type IV. Their ability to rem:dn viable is better on collagen Type 1V than on

any other substrate including huninin and libronecdn-coated surfaces. However, because sur_'ival is so short for

these isolated cohmocytes, we did not feel that we could put these cells into tile RWV unless they were cultured in

small volumes so that we could use sufficient spent medium to try to prolong their su_ viral.

We have attempted to isolate normal hunl&ll stromal cells lroln c(}Jollic surg,cal specimens. However, the

_unount of tissue that we have obtmned from our pathology deparunent h_ts been t(u_ sm*l to initiate primary

cultures of cohmic fibroblasts in sufficient quanuty to allow strom_ cell cultures. As a rcsull, we attempted to use

a mouse embryonic tibroblasl cell line, BALB/c 3T3 cells as the stromal lceder c_:ll. \\hen we did this, Lhe

3T3;MIP-101 ceils did not interacl well and did not grow together m suspension. The M IP-II11 cells actually

shunned the 3T3-coated microcarrier heads and the MIP-101 colon carcinoma cells grew in suspelision.

Our rational tbr this experiment is that these human coh_nic adelloCarclnonla cull lines develop dilterenI degrees

of differentiation when grown as xenografts in m_ce and this requires mleraction with m<msc stxomai cells. We also

reasoned that an immortal embrvtmic I-lbroblas! line may mimic colonic librobkk,,I [tlllClioll under appropriate m

11-21 !
vitro conditions. We did not repeat this with the other cell lines because they will behave much like HT-29. We

did culture HT-29 KM with 3T3 cells and found that they behave similarly to the human colonic fibroblast:HT-29

KM co-cultures.

This study was to investigate the production of novel intestinal growth factors. We had initially developed a

cumbersome bioassay in which potential factors were encapsulated in Liposomes and injected into the cecal wall of

mice. Growth and differentiation of mucin-filled goblet cells was evaluated by morphological assay of colonic

crypts overlying the liposomal implant. This assay was extremely operator-dependent and was not easily reproduced

in Boston. As a result, we attempted to develop a series of in vitro bioassays which examined the amount of

antigen expressed on the cell surface by a cell based enzyme immunoassay. The difficulty with this type of assay is

that none of the six colorectal cell lines that we examined had stable expression of the mucin related epitopes that

we were evaluating. Thus, the ability to demonstrate the goblet cell differentiating factor (GCDF) activity that had

initially been defined in the in vivo bioassay was not supported by a subsequent in vitro assay. Nonetheless, we did

evaluate the expression of EGF, bFGF, and TGF-_ 1 were released by these colon carcinoma cell lines into the

surrounding medium. Interestingly, recent data from other laboratories suggest that well or moderately differentiated

carcinomas are inhibited by TGF-_ 1, whereas poorly differentiated cell lines may be stimulated by TGF-[] 1. Our

results indicate that LS-174T cultures plateaus as the TGF-13 1 concentration increases. However, the other three

colon carcinoma cell Lines did not demonstrate a consistent relationship among the proliferation, viability and

TGF-_3 1 level. MIP-101 cullures, /or instance, demonstrate a decrease in TGF-_ 1 concentrations even as they enter

a plateau phase.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 4/91 EXPIRATION: 4/94

PROJECT IDENTIFICATION: 962-23-01-05

NASA CONTRACT NO.: NAG-520

RESPONSIBLECENTER: JSC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

,Journals

Jessep. LM. Goodwin. T.J. and Spaulding G. Prospects for use of microgravity-based bioreactor to study

three-dimensional host-tumor interactions in human neoplasia. J. Cell Biochem.. 51. 290-300 (1993).

Jessup, J.M. Brown K. lshii S. Ford R. Goodwin T.J. Spaulding G.F. Simulated microgravity does not alter epithelial cell

adhesion to matrix and other molecules.. Adv. Space Res.. 14(8), 71-76 (1994).

Spaulding, G.F. Jessup J.M. and Goodwin T.J. Advances in cellular construction. J. Cell Biochem., 51. 249-251 (1993).

Presentations

Jessup J., Goodwin T. "Simulated microgravity improves production of colonic growth factors." A/AA Space Programs

and Technologies Conference and Exhibit, September 21-23, 1993, Huntsville, AL. A1AA-93-4098.

Jessup, J.M. Fitzgerald W. Polanec J. Ford R. Goodwin T. Spaulding G.F. Brown D. "CEA production in human colon

cancer." 1994 Meeting of the Tissue Culture Association, Research Triangle Park. NC. June, 1994.

Jessup. J.M. Thomas P. Ford R.D. Ishii S. "Homotypic adhesion mediated by carcinoembryonic antigen (CEA) in

colorectal carcinoma cells involves CD44 and NCA." Keystone Symposium. Cell Surface and Tissue Engineering Meeting,

Taos, NM, February, 1994.
Three-Dimensional Tissue Interactions in Colorectal Cancer Metastasis

PRINCIPALINVESTIGATOR:Dr. J. M. Jessup New England Deaconess Hospital

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this project is to test the fidelity with which microgravity models three-dimensional tissues by

assessing how well microgravity effects the molecular and biological function of MIP-101, a human colorectal

carcinoma.

TASK DESCRIPTION:

MIP-10I is a poorly differentiated adenocarcinoma of the colon that was derived from the ascites of a patient who

had widespread metastases within the abdomin',d cavity. MIP-101 cells are grown in the rotating wall vessel

(RWV) with or without normal host cells and assessed for the production ot carcinoembryonic antigen (CEA - a

180 kDa glycoprotein that is produced by carcinomas and used clinically as a tumor marker) and for biological

behavior including adhesion and metastasis. Cells grown in microcarrier bead cultures in the RWV under simulated

microgravity are compared to similar MIP-101 cultures grown on microcarner beads in stationary culture as well as

in conventional monolayer cultures.

TASK SIGNIFICANCE:

One or the prime go_s of the biotechnology program at NASA/Johnson Space Center is to determine whether

cultivation of cells in microgravity produces three-dimensionaJ cultures that mimic the morphology and function of

tissues in living animals or humans. The MIP-101 cells are an excellent test of this because they are poorly

metastatic in experimental models of me_stasis in athymic nude mice and do not produce CEA in conventional

monolayer culture systems. We have shown that CEA injected into mice enhances production of liver metastases

by MIP-101 cells and that MIP-101 cells will metastasize when implanted into the abdominal cavity after producing

CEA. MIP-101 cells placed in the subcutaneous tissue of the mouse do not metastasize and do not produce CEA.

Furthermore, cells grown on plastic or conventional substrates such as Matngel or laminin are neither metastatic

nor induced to produce CEA.

The conventional interpretation of these results is that the microenvironment (the three-dimensional environment)

of the abdominal cavity induces MIP-101 cells first to produce CEA and then to develop blood-borne metastases in

the liver and lungs of nude mice. Early experiments in the RWV question this convention',d interpretation of the

effects of host microenvironment, because they demonstrated that CEA production may be induced in MIP-101 cells

when they are grown in the RWV in the absence of any abdominal cavity stromal cells. This suggests that the

MIP-101 cells may produce CEA when they are "allowed to grow in three dimensions. Thus, the absence of CEA

production in subcutaneous tumors is due to an inhibition of CEA production by the subcutaneous tissue rather

than promotion of CEA production and metastatic potential by the abdominal cavity.

This system is an excellent model in which to test the fidelity of the RWV culture system because the tlrst stage in

metastasis by MIP-101 cells appears to be the induction of CEA production, followed by the acquisition of the

ability to develop experimental metastases after injection into the spleen of nude mice. Assessment of fidelity of

the RWV culture system is simplified by first testing for the production of CEA, tumor marker, then assessing the

biological aspects of metastasis.

II-213
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

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PROGRESSDURING FY 1994:

The primary goal of the Biotechnology Program at NASA/Johnson Space Center is to determine whether cells

cultivated in microgravity produce three-dimensional cultures that mimic the morphology and/unction of tissues in

living animals or humans. The MIP-101 cells are an excellent test of this because they are poorly metastatic in

experimental models of metastasis in athymic nude mice and do not produce CEA in conventional monolayer

culture systems. We have shown that CEA injected into mice enhances production of liver metastases by MIP-101

cells and that MIP-101 cells will metastasize when implanted into the abdominal cavity as they produce CEA.

Recently, a CEA-producing transt'ectant of MIP-101 cells was round to be metastatic in nude mice. However,

parenteral MIP-101 cells placed in the subcutaneous tissue of the mouse do not metastasize and do not produce

CEA. Furthermore, cells grown in plastic or conventional substrates such as Matrigel or laminin are neither

metastatic nor produce CEA at detectable levels by either RT-PCR or western blots.

Since the three-dimensional growth in the peritoneal cavity induces the production of CEA, it was thought that

peritoneal stromal cells were able to induce CEA production by MIP-101 cells. Interestingly, when MIP-101 cells

were grown as three-dimensional colonies in the rotating wall vessel (RWV), CEA was released into the medium,

and immunoperoxi 'dase stmning of MIP-101 cultures revealed that MIP-101 cells produced CEA in the majority of

CEA cells forming three-dirnensional aggregates. Thus, it appears that production of CEA by MIP-101 cells is

enhanced by three-dimensional growth as opposed to two-dimensional growth in monolayers.

Recently, more data has been obtained to support this interpretation. Interestingly, some experiments have shown

that growth in Petri dishes or in T-25 flasks leads to CEA production as determined by western blot analysis as well

as by enzyme immunoassay of the spent culture medium. RT-PCR demonstrates gene transcripts in these

conventional culture systems when MIP-101 cells have been cultivated for more than 8 days. The RT-PCR,

however, shows that the gene transcripts are still quite low in number and that, if RT-PCR is pertormed under

stringent conditions, the quantity of mRNA for CEA is below the limits of detection. In contrast, RT-PCR and

western blots clearly demonstrate the presence of the 180 kDa protein in RWV cultures of MIP-101 as early as 4

days alter the initiation of RWV cultures. In addition, CEA proteins are identified by immunoperoxidase staining at

day 4 as well as by western blots of extracts of MIP-101 cells beginning at day 8. The findings of low CEA

production by MIP-101 cells in Petri dishes and T-25 flasks was somewhat unexpected, but was lbund to be

associated with overcrowding and "piling up" of MIP-101 cells as the cultures grew vertically. Thus, in the late

phases of the MIP-101 cultures, since they are not contact-inhibited, the cells assume a three-dimensional formation

that is somewhat similar to the aggregates that are formed in the RWV. Thus, it is clear that there is a very low

amount of CEA produced in MIP-101 cells which can be dramatically increased as the cells enter a three-dimensional

culture lbrmation.

The factors that regulate the three-dimensional formation and how this alters cell growth are being investigated. It

is clear that, in the three-dimensional aggregates formed in the RWV, the metabolic rate of the MIP-101 cells is

dramatically increased. A comparison of the MIP-101 cells grown in zero head-space T-25 flasks with the RWV at

similar cell concentrations indicates that tar more H _ ion and CO2 are produced in the RWV than in the monolayer

culture. However, the amount of glucose utilized is not signiticantly different. This suggests that an alternative

fuel source is being used by these cells in the RWV that leads to the production of acid metabolites. Future

experiments are designed to determine how these different metabolic pathways are activated because they may impact

on the regulation of CEA production.

In addition, studies are underway to identify how the peritoneal cavity improves the metastatic potential of these

MIP cells and, notwithstanding the effects of MIP cells grown in isolation on CEA production, there are still

stromai cell:MIP cell interactions. Recent work with Dr. Catherine Chen, who is doing a research fellowship in

Dr. Judah Folkman's laboratory, indicates that MIP-101 ceils grow preferentially along the greater curvature of the

stomach of nude mice. Dr. Chen has found that most human neoplasms prefer to grow in this part of the peritoneal

cavity as compared to the mesentery or other peritoneal surfaces in the abdominal cavity. If this is true, then it

should be possible to isolate the cells that support this growth and use them as stromal cells in future RWV

co-cultures with MIP-101 cells. We plan to do this in the next part of the fiscal year as well as to investigate the

metabolic pathways that are involved with induction of CEA production by MIP-101.

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I1-214
STUDENTS FUNDED UNDER RESEARCH: TASKINITIATION: 1/93 EXPIRATION: 1/96

PROJECTIDENTIFICATION:962-23-01-13

NASA CONTRACTNO.: NAG-650

RESPONSIBLECENTER: JSC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Jessup, J.M. Brown K. Ishii S. Ford R. Goodwin T.J. Spaulding G.F. Simulated microgravity does not alter epithelial cell

adhesion to matrix and other molecules. Adv. Space Res.. 14(8), 71-76 (1994).

Jessup, J.M. Goodwin T.J. and Spaulding G. Prospects for use of microgravity-based bioreactors to study

three-dimensional host-tumor interactions in human neoplasia. J. Cell. Biochem.. 51, 290-300 (1993).

Spaulding, G.F. Jessup J.M. and Goodwin T.J. Advances in cellular construction. J. Cell. Biochem., 51. 249-251 (1993).

Presentations

Jessup, J. Goodwin T. "Simulated microgravity improves production of colonic growth factors." AIAA Space Programs

and Technologies Conference and Exhibit, September 21-23, 1993, Huntsville, AL. AIAA-93-4098.

Jessup, J.M. Fitzgerald W. Polanec J. Ford R. Goodwin T. Spaulding G.F. Brown D. "CEA production in human colon

cancer." 1994 Meeting of the Tissue Culture Association. Research Triangle Park. NC, June 1994.

Jessup, J.M., Thomas P. Ford R.D. Ishii S. "Homotypic adhesion mediated by carcinoembryonic antigen (CEA) in

colorectal carcinoma cells involves CD44 and NCA." Keystone Symposium, Cell Surface and Tissue Engineering Meeting,

Taso, NM, February 1994.
Applications of Atomic Force Microscopy to Investigate Mechanisms q_ Protein Crystal Growth

PRINCIPALINVESTIGATOR:Dr. John H. Konnert Naval Research Laboratory (NRL)

GO-INVESTIGATORS:

K. Ward

P. D'Antonio

Naval Research Laboratory (NRL)

Naval Research Laboratory (NRL)

TASK OBJECTIVE:

The research objective is to use Atomic Force Microscopy to study protein crystal growth mechanisms by

extending the pioneering work of Durbin et al (1992) to include crystals other than lysozyme, and by applying

image analysis methods not generally available to others to aid in the interpretation of crystal face images observed

by this technique. Specific objectives include:

• To modify an AFM liquid sample cell for use as a crystal growth cell for protein crystals. This cell has a

flow-through system which will ',allow protein supersaturation to be controlled by varying the temperature of the

crystallization solution bathing the crystal being observed:

• To determine by direct observation of developing crystal laces the mechanism of crystal face growth for a variety

of growth conditions including solution composition, degree of protein supersaturation, temperature, growth rate,

and microgravity;

• To use crystal etch figures methods and direct observation of growing crystal faces observed by AFM to classify

and determine the number of crystal imperfections which occur under a variety of crystal growth rates and

conditions, including the examination of faces of single crystals prepared under microgravity conditions;

• To demonstrate that the observed diffraction quality of protein crystals prepared under a variety of conditions can

be correlated with the number and type of crystal detects observed using AFM; and

• To determine whether any observed changes in the appearance of the surface of protein crystals can be correlated

with the growth cessauon phenomena of protein crystals.

TASK DESCRIPTION:

Proteins will be prepared for examination by AFM using conventional vapor diffusion, hanging drop methods, and

in the temperature-controlled crystallization cell described by Ward, Perozzo and Zuk (1992).

The goal will be to prepare crystals of a given protein using different growth rates by carefully controlling the

degree of supersaturauon and other growth parameters. Single crystals prepared for these studies will be

characterized by x-ray diffraction analyses using standard data reduction and "analysis techniques. The diffraction

q"uality will be quantified using the relative Wilson plot analyses described by DeLucas et al (1991).

In addition to preparing crystals under unit gravity conditions, we also intend to submit these proteins for

crystallization experiments under microgravity conditions. These experiments will be performed by Keith Ward

either as part of the co-investigator protein crystallization program at the University of Alabama-Birmingham or as

part of his own Flight Investigation Project which has been submitted in response to the recent NRA.

A number of proteins have been selected for this application of AFM to protein crystal growth studies. Each one is

readily availableg easily crystallized, and exhibits unique crystallization properties.

! II iii ii I Ili * ii t I i I It I itl I I II It I I I I I I I t I i i iil I i i i i t I I I l I i iil i! t I i i I i il ii I I I i i gI i I I II i ii i I i iiii Ii I I I I I I I I lii i it i iI I I It I I Iit I Ill I I I I II I Ill I I ii I II I I I I Ul l i i i ill II I III III III III Ill Ill I II III Iltll tl III I gII I II III Ill Ill Ill III III iiinllll iii iii iii iii ill i

11-2 1 6
II. MSADProgramTasks-- Ground-based Research Discipline: Biotechnology

TASK SIGNIFICANCE:

This project will, for the first time, provide unique information about protein crystal growth processes by direct

observation of crystal faces in their growth medium. Successful results will provide new evidence for the effect ot

crystal growth conditions, including microgravity, on the defect structures and diffraction quality of protein crystals.

Results derived from this project will, theretbre, be of direct significance to NASA-funded eftbrts auned at preparing

high-quality protein crystals for structural investigations by effectively utilizing the unique microgravity

environment of space platforms.

PRO6RESS DURiN_ FY 1994:

Techniques have been developed to directly observe with the AFM the growth kinetics of protein crystals in

solution whose concentrations span those employed for the growth of crystals suitable for single crystal diffraction

experiments. These observations at the molecular level permit the macroscopically observed crystal growth rates to

be factored into two components:

1. The growth of existing features as a function of crystallographic orientations.

2. The nucleation of new features on the existing surlace as a function of crystallographic orientation. In addition,

our system allows both components to be investigated as a function of composition and temperature of the

solutions ll"om which the crystals grow. A journal article is being prepared.

During the next fiscal year, we will extend our studies to other protein crystals, in order to test the general

applicability of this method for discerning details about protein crystal growth mechanisms.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-23-08-25

NASA CONTRACT No.: H-07973D

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Konnert, J.H., D'Antonio, P.. and Ward. K.B. Observation of growth steps, spiral dislocations and molecular packing on

the surface of lysozyme crystals with the atomic force microscope. Acta Cryst., vol. D50, 603-613 (1994).

Konnert, J.H., D'Antonio, P.. and Ward. K.B. Observing the growth of protein crystals. NRL Review, 130-132 (1994).
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

Neuro-endocrine O_Xanoid Assembh¢ m Vitro

PRINCIPAL INVESTIGATOR:Dr. Peter I. Lelkes University of Wisconsin. Milwaukee

CO-INVESTIGATORS:

B.R. Unsworth Marquette University

TASK OBJECTIVE:

The specific aims of our project, entitled "Neuro-endocrine Organoid Assembly In vitro" are as follows:

1. To assemble adrenal medullary endothelial and parenchymal cells into functional organoids. Progress will be

monitored by evaluating, a) morphology dight microscopy and ultrastructure), b) intercellular communication

(immunocytochemistry), c) functional maturation and its hormonal control by corticosteroids, d) the expression of

phenotypic, biochemical, and molecular markers.

2) To compare the usefulness zmd efficacy of NASA vessels with conventional co-culture systems (monolayer

culture, suspension culture and 3-dimensiona/gel assembly). The ttme course, and the extent of neuro-endocrine

cell differentiation, under the different culture conditions will be evaluated (as in 1).

TASK DESCRIPTION:

Our long term research goal is to understand the fimdamental mechanisms of neuro-endocrine gland assembly and

differentiation, in our particular m_xtel system, the adrenal medulla, neural crest-derived cells of the

sympathoadrenal lineage differentiate into neuro-endocnne chromaffin cells. We are particularly interested in the

role of the microenvironment in this process. We have previously shown that during assembly and maturation of

the adretr, d medulla, as m other endocrine organs, parenchyma/cells and endothetiM ceils interact through reciprocd,

intercellular signals. Such signals may constitute soluble factors, heterotypic cell contacts, or may be derived from

organ-specific extracellular matrix components. These cues comprise part of the epigenetic repertoire, which

induces the ordered differentiation of both cell types into what is known as the "endocrine structure".

Using conventional 2-D culture techniques, we have shown that m co-culture with adrenomeduilary endothelial

cells, chromaffin-cell-derived pluripotent PC12 cells differentiate l()wards the neuroendocrine phenotype. We,

therefore, hypothesize that capillary endothelitd cells in the adrenal medulla provide some of the organ-specific,

differennative cues whtch contribute to the neuroendocrme differentiation of the chromaffin precursor cells.

In this proiect we extend our on-going in vitro studies on the inechanisms of organ-specific diiferentiation by using

alternate methods of co-culture. We are exploiting the esdmnced potential offered by the NASA vessels to analyze

the temporal assembly of co-cultured adrenomedullary endotheli',d and parenchymal cells into functional,

organellel-like structures (organoids). The simulated microgravity environment of the NASA vessels has been

shown to randomize gravitational vectors and minimize detriment_d shear lorces routinely encountered in

convention',d three-dtmension_d suspension cultures in spinner flasks. We anticipate that the favorable culture

conditions in the NASA vessel will accelerate differcntiative, heterotypic ceil-cell contacts and thus lead to

differentiated organoid-_Lssembly m vitro.

TASK SIGNIFICANCE:

In this study, we attempt, for the first time, to generate neuro-endocrine organoicks in vitro by co-culturing different

cells isolated from the s_une organ under simulated microgravity conditions. By using the NASA cell culture

vessels as a novel, alternate approach to conventional suspension culture m spinner flasks, we are participating in

NASA's assessment of simulated imcrogravity conditions for organ-specific culture and cellular differentiation. As

previously shown, a major advantage of using the Rotating Wall Cell Culture Vessels (RWVs) developed by

NASA is the enhanced cell viability and tissue differentiation under conditions of simulated microgravity and

minmaized shear stress.

11-218
Theunique conditions in the NASA vessels are believed to enhance cellular interactions and thus differentially

accelerate and/or facilitate these processes. In complementing a number of other parallel studies within this

program, our project is the first one specifically designed to examine the effects of microgravity on heterotypic

interactions between parenchymal cells and microvascular endothelial cells isolated from the same organ1 namely the

rat adrenal medulla. Such intercellular interactions are believed to be of importance during all phases of the

development of endocrine organs, from the earliest stages of embryonic genesis through postnatal maturation.

By using NASA's RWVs as the prime cell culture environment, we will be able to assess whether the spatial

arrangement of the functional organ is 'a/fected by gravitational forces/vectors. Based on our preliminary

observations, we hypothesize that by using the RWVs, we will be able to eliminate gravitational vectors, such as

those present m static two-dmaensional monolayers or in suspension cultures, and thus obtain a more realistic

representation of tissue assembly, as seen in vivo.

Our co-culture system is ideally suited for dissecting the microenvironmental effects (heterotypic cell interactions,

microgravity, etc.) on neuro-endocrine differentiation of adrenal medullary, chromaffin cells, since many of the

phenotypic and genotyhpic markers for organ specific differentiation of these cells are well characterized.

Furthermore, our model system of heterotypic co-culture of adrenal medullary cells is of particular relevance in view

of our recent finding that rnicrogravity specifically "alters the expression of pivotal enzymes in the catecholamine

synthesizing cascade. Thus, our model system is also suitable to explore the cellular and molecular basis tor

(micro)gravity sensitivity, e.g., of signal transduction mechanisms involved in neuroendocrine hormone synthesis

and secretion.

Based on the first year of practical experience with one of the RWVs, we are confident that the enhanced cellular

viability and differentiation achieved by culturing the cells under similar microgravity conditions will be of general

advantage for developing new concepts for tissue culture and tissue engineering. Specifically, we anticipate that

this novel environment will be beneficial for culturing and/or co-culturing fragile cell types, e.g., when isolated at

early stages of embryonic development. We anticipate that within a reasonable time period, we will be able to test

our model tbr organogenesis and differentiation during one of the future Space Shuttle missions.

PRO6aESS DURIN_ FY 1994:

1. As indicated in la.st ye_tr's progress report, we spent the first year of the grant on refining our basic heterotypic

cell culture systems using conventional monolayer and suspension cultures. In collaboration with scientists at

JSC, (specific',dly the group of T. Goodwin) we explored the suitability of the various available rotating-wall

vessels (RWVs) for growing adremd medullar3' parenchymal and endothelial cells, alone and in co-culture, under

simulated microgravity conditions. Based on those preliminary findings, we decided to continue our studies in the

Slow Turning Laterial Vessel (STLV) type RWV.

2. After in-servicing a graduate (Ph.D.) student_ Daniel Galvan, at JSC, two STLVs were shipped to Milwaukee in

the beginning of 1994. We arc currently carrying out the expenments according to the plans detailed in the specific

aims: we are assessing the effects of simulated microgravity on neuro-endocrine organ-assembly by co-culturing

transformed rat adrenal medullary parenchymal cells (PC12 pheochromocytoma cells) with organ-specific

microvascular endothelial cells fRAME, rat adrenal medullary endothelial cells). In spite of some technical

difficulties with the device drive units, the prolonged duration of each of these experiments (up to 3 weeks), and the

llinited ntnnber of vessels available ftwo), we have obtamed some encouraging preliminary result._:

a) We optimized the conditions for culturing each of the cell types alone and in co-culture on microcarrier beads in

the STLV. The efficiency of cell culture w_.s assessed, e.g., by the rates of glucose utilization rate and proliferation,

respectively.

b) Preliminary visualization by routine histological staining of the ensuing three-dimensional cell aggregates

suggests that both PC 12 and RAME cells from histiotypic assemblies on the beads; large clumps/aggregates of

viable PC12 cells reminiscent of parenchymal acini and contact-inhibited monolayers of RAME cells. By contrast,

in the co-cultures, we observed organotypic assemblies of mixed populations, in which homotypic interactions

prevail. Thus, PC12 remain clustered into nest-like a_ssemblies, surrounding (or surrounded by) RAMEs.

11-21 9
lI. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

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Importantly, .[or the first time. we also observed in these co-cultures, the assembly of RAMEs into what appear to

be capiUa_ structures. These experiments are currently being repeated to establish the reproducibility of the

exciting observation that co-culture, under simulated microgravity, results in organotypic assembly of adrenal

medullary cells and enhances organ-specific differentiation of both parenchymal and endothelial cells. Currently, the

findings are being substantiated by molecular biological and immunochemical techniques of the light and electron

microscopic level. As described below, we implemented a novel quantitative PCR technique for measuring the

expression of genes related to neuroendocrine differentiation. In ",addition, studies are under way to assess, by

immunohistochemical means, whether the seemingly histotypic assembly of neuro-endocrine "organoids" in the

STLV is accompanied by the enhanced expression of organ-specific differentiation markers, such as the

catecholamine synthesizing enzymes in adrenomedullary PC12 cells.

c) We previously reported that PC12 cells and RAME formed organ-specific assemblies in conventional suspension

cultures which were maintained at low speed with minimal shear forces in the absence of microcarrier beads. In

repeating the experiments, we now have substantiated these findings. Specifically, RAME cells were found to

attain configurations which are reminiscent of the formation of new blood vessels (angiogenesis). Since, in the

STLV ceils cannot be cultured without beads, we have begun to optimize conditions for culturing the cells in a

small (10 ml) High Aspect Ratio Vessel (HARV). These experiments are designed to permit direct comparison

between different "beadless" cell cultures in stirred fermentors vs. in a RWV. We expect that this comparison will

yield relevant information on the beneficial effects of simulated microgravity on organ-specific differentiation.

3. As detailed above, the focus of our studies is to assess difterent/al expression of organ-specific marker genes by

using molecular biological techniques. In the past year, we have made significant progress in several

complementary areas:

a) We continue to assess the effects of simulated microgravity on differential gene expression, mainly via RT-PCR.

To increase the reliability of our results and to eliminate the possibility of false positives, we have synthesized,

verified, and tested a number of previously not available species (rat)-specific PCR primer pairs for the following

rat-specific genes:

Comparator genes for relative quantitation: glyceraldehyde-phosphate-dehydrogenase (GAPDH), _-actin and

(mitochondrial) rRNA

Catecholamine s_vnthesizin_ enzymes: tyrosine hydroxylase (TH), phenylethanolamine-N-methyltransferase

(PNMT), dopamine-[_-hydroxylase (DBH), aromatic-dopa-decarboxylase (DDC)

protooncogenes: c-fos

Catechoiamine metabolizing enzymes: monoamine-oxidase A (MAO-A), and B (MAO-B)

ExtracelJular matrix proteins: fibronectin (FN). Currently, rat-specific PCR primer pairs and RNA/DNA probes are

being established for other extracellular matrix proteins, such as collagens I and IV, laminin A and B1 chains, for

which so tar only the murine sequences are known.

b) Having established species-specific PCR primer pairs and probes, we are currently constructing species-specific

sense and antisense RNA probes for Northern blotting, RNAse protection assays and for in situ hybridization

studies. These techniques will complement our quantitative PCR approach (see below).

4. In the pask we have semi-quantitated differential gene expression by RT-PCR using established comparator

genes, such as GAPDH, _-actin or rRNA (Lelkes, et. at., FASEB J. in press, see appendix). Recently, we

established a rigorous, quantitative PCR-assay, termed competitive RT-PCR. In this assay, a so-called PCR mimic

DNA template is added to the reaction buffer prior to the PCR step. This mimic uses the same primers as the

endogenous MRNA sequence, but slightly differs in size, which allows its separation from the endogenous one on

the DNA gel. Therefore, mimic templates compete with endogenous cDNA for PCR substrates. By adding a

known number of mimic templates equal to the number of endogenous templates into the PCR reaction, two

products are obtained of equal intensity and slightly different sizes as visualized on a DNA electrophoresis gel. To

date, we have generated and successfully tested PCR mimics for TH, PMNT and FN (see below).

5. As detailed above, our long term goal is to study the molecular mechanisms by which microgravity might alfect

cellular differentiation. Specifically, we want to discover novel molecule(s) involved in the microgravity-induced

neuroendocrine differentiation. Towards that goal, we have in the last year implemented the most recently developed

molecular technique, called Differential Display. Using this technique, the RNA populations of both

microgravity-treated and control samples can be displayed on a 2-D sequencing gel. The identities of any known or

unknown RNAs which are differentially expressed in the PC12 cell culture in microgravity vessel can be revealed by

11-220
further PCR, chining and sequencing. So far, we have successfully tested this technique and optimized the assay

conditions. Current experiments are under way to employ the differenual display assay for studying the genes which

are differenti_flly activated in the PC 12 cells exposed to microgravity.

6. Other related studies:

a) As described in last year's report, we used some of the biochemic',d and molecular techniques m :tssess the eflects

of microgravity on the expression of catecholamine synthesizing enzymes in the adremfl medulla of rats flown

aboard the Space Shuttle Mission STS-54. In addition to presenting these resulLs at the annmfl meeling of the

American Society of Cell Biology (Lelkes, et _fl., Mol. Boil. Cell, vol 4 Supply:109a, see appendix _, a paper

entitled "Microgravitv Decreases Tvrosine Hvdroxvlase Expression in Rat Adrenals" is currently in press m the

FASEB Journal (see appendix). In brief, our data show that the expression and specific activi;y of tyrosine

hydroxylase (TH), the rate limiting step in catechol_unine swithesis was specifically affected by microgravily. By

contrast, phenylethanolamine-N-methyl-Transferase (PNMT), the chromaffin cell-specific enzyme which converts

norepinephrine to epinephrine was not affected during space flight. We hypothesized that these observed effects of

space flight were not due to stress response during reentry because of the relatively long time course (about 12

hours) of TH depression aid lowered catecholamine contents. Furthermore, based on evidence m the literature, we

speculated that microgravity may be exerting its effect on catecholamine synthesis by acting on specific,

microgravity-sensitive signal transduction pathways.

We have now further substantiated these conclusions by analyzing adrenals of(10 days) tail-suspended rats, a

putative, ground-based control R)r weightlessness. For these studies, we used for the first time our newly developed

method of competitive PCR to quantitate TH and PNMT expression. In contrast to the pattern _)I TH and PNMT

expression in the adremds of space-flown animals, we found that in the adren',ds of tail-suspended rals, the

expression (mid specific activities) of both TH and PNMT were _ by, respectively, 30'7,,, ;rod 100'7,,. This

pattern of elevated catecholamine synthesizing enzyme levels is typical lor stress situations, suggesting thai

prolonged tail suspension, while presumably suited for studying the effects of simulated weightlessness on muscle

physiology, might not be suited to model any effects of microgravity on the (neuro) endocrine system.

b) In order to simplify cell culture in the RWVs, the biotechnology group at JSC recently developed a novel cell

culture medium c',dled GTSF-2. In collaboration with the scientists in that group, we completed our evaluation of

GTSF-2 using a number of different cell types and other with our cells. A paper, entitled "GTSF: A New.

Versatile Cell Culture Medium jbr Diverse Normal and Tran,s_?rmed Mammalian Cells" is currently m press m the

Joum_ In Vitro. Our data suggest that GTSF-2, by itself or with minor modifications, is well suited to mamlam

the growth of a variety of cell types including neuronal cells, primary, cultures of endothelial cells from humans and

rodents, and several lines of transformed cells.

c) An exciting spinoff of our ongoing studies is the use of RWVs to culture normal proximal tubular epitheli_d

cells isolated from human kidneys. These cells are notoriously difficult to handle and very rapidly de-differentiate m

conventional 2-D cultures. In collaboration with Dr. T. Hanunond (U. Wisc. Med. School) and Clonelics Co. (San

Diego), we have used the simulated microgravity in an STLV to establish both morphologically and functionally

highly differentiated cultures of these cells. An abstract (Human Renal Epithelial Cells in Culture Differentiate

Under Simulated Microgravity) will be presented at the upcoming Annum Meeting of the American S(x:iety lot Cell

Biology. A manuscript detailing our results is in preparation. Moreover, the budding collatx)ration with a small

business company raises the prospect that, besides their usefulness as novel research tools, RWVs can be used for

developing a cornmercializable product which will be important for basic and applied biomedical studies.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: l

TASK INITIATION: 11192 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-23-01-12

NASA CONTRACT NO.: NAG9-65]

RESPONSIBLECENTER: JSC

!I-221
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Lelkes. P.I., Ramos, E.M.. Chick. D.M.. Liu. J. and Unsworth, B.R. Microgravity decreases tyrosine hydroxylase

expression in rat adrenals. FASEB J.. in press, 11994).

Lelkes, P.I., Ramos, E.M.. Nikolaychik. V.V., Wankowski, D.M., Unsworth, B.R. and Goodwin, T.J. A new, versatile

cell culture medium for diverse normal and transformed mammalian cells. In Vitro. in press. (1994).

Presentations

Galvan. D.L.. Wankowski, D.M., Bacciao, Dillberger, A.. Karmiol. S., Hammond. T.G. and Lelkes P.I. "Human renal

epithelial cells in culture differentiate under simulated microgravity." To be presented at the Annual ASCB Meeting, Dec.

1994.

Letkes. P.I., Ramos, E.M., Chick. D.M.. Liu. J. and Unsworth B.R. "Space flight alters catecholamine-synthesizing

enzyme expression and activity in the rat adrenal medulla." Annual ASCB meeting, Dec. 1993,

__!_|__|_______!!__!___|___|||!___|!___!_e|_e!___!_!!__!____!!_______I_||I______I||_______O__________|_!|_a___|I__|__|_|||I___________!e___|II|_!__!____!_|__|_I|_||_|______|__|______!_e__|___!__|____IIII|_|_____ae!_e!|||!|_!|_!_!__I_tI|____||_|

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Formation of Ordered Arrays of Proteins on Surfaces

PRINCIPALINVESTIGATOR:Prof. Abraham M. Lenhoff University of Delaware

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The goal of the project is to investigate the formation of ordered arrays of proteins at solid surfaces. Two parallel

approaches are employed:

1. An empirical study, by scanning probe microscopy (SPM), of the effects of protein and surface parameters on

array tbrmation;

2. A fundamental examination, by molecular simulations and surface forces apparatus measurements, of the protein

- protein and protein - surface interactions that give rise to protein adsorption and ordering.

Although our primary interest is in proteins, insight can be provided in both the simulations and experiments by

corresponding experiments on spheres. For this purpose, the FY94 task included study of amidinated polystyrene

latex particles.

TASK DESCRIPTION:

The tasks begun in FY94 fall into three categories:

1. Atomic force microscopy (AFM) of proteins and latex spheres on surfaces, complementing the purely

protein-related work performed and proposed previously. Use of AFM makes possible the investigation of behavior

at non-conducting surfaces, specifically mica, while examination of latex spheres makes possible discrimination

among multiple possible explanations for changes in adsorption extent as a function of salt strength.

2. Calculation of the energetics and hence the isotherms tor adsorption of ordered arrays of particles at charged

surfaces. Our computations to date on ordered arrays have examined only spherically symmetric particles, and the

additional studies are intended to investigate the effects of charge asymmetry and possibly of particle shape.

3. Surface torces measurements of protein - surface interactions. Experimental measurements of the interaction

energy of ordered arrays of streptavidin, immobilized on one surface, with a second charged surface.

TASK SIGNIFICANCE:

Ordered arrays of proteins are of interest tot two main reasons:

1. Protein structure determination. X-ray crystallography is still the workhorse for determination of protein 3-D

structures, but other techniques have begun to emerge. One class of methods that emerged during the 1980s is that

of structure determination on two-dimensional crystals, with techniques such as electron microscopy employed to

probe the structures of the constituent molecules. The 2-D arrays we will study would be suitable for such

investigations. Furthermore, it is possible that such arrays can serve as templates for the epitaxial growth of 3-D

crystals.

2. Synthesis of novel materials. The complex 3-D structures of proteins give them functional properties that are

also complex, and in addition can be produced reproducibly. Given proteins with the appropriate functions, ordered

monolayers of protein molecules at solid surlhces may represent materials with useful properties that make various

applications possible. Examples include electronic devices and "biocomposite" materials.

!1-223
lI. MSADProgramTasks--Ground-basedResearch Discipline:Biotechnology

i ii i I | t i | | I Go I| | i I| | i ! o |! aII | | ! | |t | | i | i t i | I | J i I I II I | I ! I I n | i i o I I _| t i ! i | o i ill i i i i J_ nJ i I | i I a | | gI i I _ I _ _ I I ! III I! I i | i i ! o n i | | I it _ i Q! i i i | i i n i i | | i _ n i i i ii i i n i i i i | I I I o |J n iii i i i i i i I I * i iI | I| | i | | t | I t i | |i i I | || o || iI a I I ! * I! mI ! i I t |I t J o _ 0 _ _ i _ i i | | i _ i i _ I I * _ I I | _ | _ i

Apart from these applications, our studies of sell-assembly have a further, more fundamental purpose: the colloidal

forces driving 2-D self-assembly are the same as those giving rise to 3-D crystal growth, so understanding these

forces and their interactions is expected to lead ultimately to insights into manipulation of both 2-D and 3-D

structures. It is 'also the isola0on of these colloidal forces from other disturbances that provides the incentive for

microgravity-based research in this area, as in protein crystal growth.

PROGRESSDURING FY 1994:

Progress is summarized separately for the three areas listed above.

1. AFM studies of adsorption: We have studied both kinetic and equilibrium aspects of adsorption of positively

charged latex particles on mica, which is negatively charged; of particular interest is the effect of ionic strength.

Adsorption kinetics are observed to be diffusion-limited. The equilibrium structures display relatively little

periodicity, but a lair degree of long-range order; in particular, the interparticle spacing decreases with increasing

ionic strength, and hence surface coverage increases with increasing ionic strength. This trend is opposite to that

observed for proteins, and the explanation for this could shed considerable light on the mechanisms involved in array

formation and, more generally, on protein crystallization. This aspect is still under investigation, but a likely

reason lies in the relative contributions of electrostatic and van der Waals interactions to the overall interaction

energy.

2. Interaction energy calculations: Our calculations of interaction energy and adsorbed amounts for arrays of

spheres have been completed (paper to appear in Langmuir). Work to extend these calculations to more realistic

arrays of protein molecules is in progress.

3. Surface force measurements: We have successfully performed measurements of the interaction energy between

an immobilized array of streptavidin molecules and a lipid bilayer coated on mica. These measurements show

evidence of long-range repulsion, presumably due to electrostatic interactions, but a more detailed interpretation and

comparison with protein - surface electrostatics computations is difficult because the charge on the bilayer side,

which is actually due to the residual charge on the underlying mica, cannot be t_ed reproducibly.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 4/94 EXPIRATION: 4/95

PROJECT IDENTIFICATION: 962-23-08-30

NASA CONTRACT NO.:NAG8-1038

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Palkar, S.A., and Lenhoff, A.M. Energetic and entropic contributions to the interaction of unequal spherical double layers.

J. Coll. Interf. Sci., vol. 165, 177-194 (1994).

Presentations

Johnson, C.A., and Lenhoff, A.M. "An AFM study of latex particle adsorption on mica." ACS Colloid and Surface Science

Symposium, Stanford, CA, 1994.

Johnson, C.A., Haggerty, L., Wu, P., Lenhoff. A.M., and Wagner, N.J. "Ordered arrays of adsorbed proteins: modelling

and observation by scanning probe microscopy," 8th International Conference on Surface and Colloid Sciences, Adelaide.

South Australia, February 13-18, 1994.

Johnson, C.A., Wu, P., Lenhoff, A.M., and Wagner, N.J. "Modelling of the formation of ordered protein arrays at

liquid-solid interfaces." AIChE Annual Meeting, St. Louis, MO. 1993.

Palkar, S.A., and Lenhoff, A.M. "Characterization of protein-surface interactions using surface forces apparatus." 8th

International Conference on Surface and Colloid Sciences, Adelaide, South Australia, February 13-18, 1994.

IIIII IIll IIIIl IIIII IIIIII IIIl IIIIII Ill Ill IIIIII IIl IIIIIIII IIIIIIIII IIIIIII IIII IIIIIIII IIIIIII lieIII IIl III IIIIIIIIIIIl Illl IIIIIl llll III Ill IIIIIIlllI IIll III III IIIIIIIIIllIIllllI llIIIIIllIII llIIIlll Ill IllIlll IIIIII III III IIIIII IIl llI III IIIn III IIII

II-224
lI. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

Crystallization Studies fn Micro g_ravity of an Integral Membrane Protein: Tire Photosynthetic

Reaction Center

PRINCIPAL(NVESTIGATOR:Dr. Jtunes R. Norris Argonne National Laboratory

CO-INVESTIGATORS:

J. Deisenhofer

M. Thurnauer

D. Tiede

P. Thiyagaralan

M. Schiffer

R. Furrer

Howard Hughes Medical Institute

Argonne NationaJ Laboratory

Argonne National Lalx_ratory

Argonne National Laboratory

Argonne National Laboratory

Free University Berlin

TASK OBJECTIVE:

The objective of this project is to determine the effects of microgravity on the crystallization of integral membrane

proteins.

TASK DESCRIPTION:

Advances in the understanding of membrane protein crystallization are important from both biological and

pharmaceutical viewpoints. Membrane proteins are responsible for many of the major biological processes such as

vision, nerve conduction, cell differentiation, photosynthesis, and respiration. Previous crystallization experiments

in microgravity have suggested that the elimination of density-driven convection and sedimentation may generally

lead to larger, better-ordered crystals for water-soluble proteins. The potential beneficial effects of microgravity on

the crystallization of integral membrane proteins have not yet been tested. The necessity of maintaining membrane

proteins in detergent micelles dunng the crystallization process suggests that the deleterious effects of gravity-driven

convection may be more significant during the crystallization of membrane proteins than water soluble proteins.

The effects of microgravity on crystallization of membrane proteins will be tested using the Rhodopseudomonas

viridis and Rhodobacter sphaeroides photosynthetic reaction centers as test proteins. The two reaction centers differ

in the proportion of the accessible surface area that is buried in the micelle environment. The comparison of Rps.

viridis and Rb. sphaeroids crystallization will provide a usefifl indicator of whether the effects of microgravity can

be linked to differences in volume traction of detergent in the detergent-protein complexes. The spaceflight and

ground control crystallization experiments will be analyzed by three techniques: optical microscopy, x-ray

diffraction, and small angle neutron (SANS) and light scattering. The optical microscopy and x-ray diffraction of

crystals will determine the effects of microgravity on crystal growth and molecular ordering. SANS and light

scattering studies on reaction center solutions at various extents of completion of crystallization will be used to

determine the effects of microgravity on the nucleation events that precede and then continue during the

crystallization process, The results of reaction center nucleation and crystallization studies in microgravity will be

relevant to the crystallization of integral membrane proteins in general.

Since 1988, despite a great deal of worldwide eftoK relatively few other membrane proteins have been crystallized

in a form suitable for high-resolution structural studies. To date, only the reaction center structures have been

solved. Many other membrane proteins have been crystallized, but the generally small crystal size and poor

diffraction quality has prevented structural determination. A complicating factor is the presence of the detergent

micelle. The effect of the detergents on the crystallization process is unknown. However, the effects of small

amphiphiles on crystallization suggest that micelle size or radius may play an important role in determining

whether protein-protein contacts predonunate to produce a crystalline structure, or whether non-specific

micelle-micelle contacts predominate to yield a less ordered array. Crystallization frequently occurs at or near the

phase separation of the detergent. This correlation between crystallization and detergent phase separation has led to

the investigation of the micelle-micelle attraction, and the role this will play in the early nucleation process.

Ultimately, the micelle aggregation must be balanced by protein-protein interactions to result in crystal formation.

II-225
TASK SIGNIFICANCE:

Current results on crystallization in microgravity have shown that the minimization of convection and

sedimentation in space leads to improved size and/or ordering of crystals for many water-soluble proteins. In several

cases, the resolution of the x-ray diffraction was better than any crystal produced on Ea_rth. In cases where the x-ray

diffraction quality did not exceed the best obtained on Earth, the space-grown crystals were still better than those in

the control experiment. These results indicate the need tot optimization of space hardware compared to the results

achieved in the laboratory, but still point to the beneficial effects of microgravity on the crystallization process.

PROGRr:SSDU_tNGFY1994:

1. Determination of Micelle Structure. During this fiscal year this project completed an analysis of detergent

micelle structure and micelle-micelle interactions under conditions used for the crystallization of an integral

membrane protein, the photosynthetic reaction center. This is the start of a project that will used small angle

neutron scattering to determine structures of intermediates in crystallization pathways of integral membrane

proteins. SANS was used to analyze tile structures of micelles from the detergents octyl-b-D-glucoside, OG, and

lauryl-dimethylamine-N-oxide, LDAO. To date, only these two detergents have been found to be useful for

crystallization of the reaction center. However, crystallization with each detergent requires distinctly different

solution conditions. The physical cause for the requirement to adjust the crystallizauon conditions tor each

detergent was not previously known, but the differences suggest that detergent properties significantly affect the

crystallization process.

Work completed this year (Thiyagarajan and Tiede, 1994 J. Phys. Chem. in press) characterized micelle structure and

inter-micelle interaction tor LDAO and OG in conditions used tot protein crystallization using SANS. This work

found that LDAO and OG micelles differ significantly in size, sensitivity to heptane triol, and in nature of

inter-micelle interactions. Our results suggest that successful crystallization methods can be rationalized in terms of

an optimization of micelle size, number density, flexibility of micelle radius of curvature, and suppression of

inter-micelle interactions. LDAO and OG miceUes were found to differ signiticandy in size and shape. The LDAO

micelle was round to be best fit as an ellipsoid with semiaxes of 30.6/_ and 19.4 A, while the OG micelle was

round to be spherical with a radius of 22.9 A. The addition of heptane triol to pure LDAO resulted in the tormation

of smaller, spherical, mixed micelles with radii in the range 17 A to 21 ,_, depending upon conditions. The results

,suggest that both micelle size and curvature restrictions may contribute to the incompatibility of LDAO for protein

crystallization in the absence of additional amphiphiles. The mixed OG-heptane triol micelle was found to be

,significandy smaller than that with LDAO, having radii in the range 15 A to 18 A depending upon conditions, and

exhibited a greater number density increase. Evidence was round tbr interaction between OG and

polyethyleneglycol, PEG, that prevents micelle aggregation at high ionic strength, and likely contributes to the

particular success of PEG as a protein precipitant when OG is used as the solubilizing detergent. These

measurements suggest that the chemical constituents in membrane protein crystallization can be manipulated to

opumize miceile size, number density and inter-particle interactions.

2. Protein Aggregation States. During this fiscal year we also initiated SANS investigations that will eventually

be used to c "haracterize structure and aggregation state of the reaction center protein as a function of its progress

through the crystallization process. During this year, initial focus was on determining the solution structure of the

reaction center as a function of crystallization conditions betore super-_turated states are reached. SANS data

acquisitions were completed on reaction center aggregation states in OG and LDAO, and as a function ionic strength

in these detergents. These measurements found a striking dependence of reaction center aggregation state on

detergent and ionic strength. The SANS results suggest that the reaction center exists in an equilibrium between a

monodispersed lorm and an unusual linear aggregate. These studies found that the equilibrium is shifted far towards

the linear aggregate with LDAO as the solubilizing detergent at low ionic strength, but shifts to the monodispersed

form at high ionic strength ( 1 M NaCI ). Conversely, with OG as the solubilizing detergent the equilibrium was

found to be shifted towards the aggregate at high ionic strength, while the monodispersed form is seen to

predominate at low ionic strength. While further structural and physical chemical analyses are currently underway,

these results show that the existence of the monomeric reaction center state in each detergent is co-incident with

11-226
conditions that eliminate miceile interactions. This work is uncovering the connections between micelle properties,

protein solubilization and crystallization.

Preliminary SANS data was 'also acquired on reaction center aggregation in OG\PEG solutions that represent

conditions at the start of a crystallization expermaent. Although further, ongoing analysis and data acquisition are

needed, the preliminary, results clearly demonstrate that addition of PEG at concentrations below that needed to

induce reaction center crystallization induces a significant aggregation of the reaction center. This data provides

evidence that a majority of the reaction center population is likely to exist in aggregates in the dimer to decamer

size range at the start of the crystallization process. This data provides evident for the importance of the aggregates

states either as competitors to productive crystallization pathways, or possibly as functional intermediates on the

actual crystallization paths. Ongoing work will distinguish between these possibilities.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 4/93 EXPIRATION: 4/96

PROJECT IDENTIFICATION: 962-23-08-29

NASA CONTRACT No.: H-13058D

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Thiyagarajan, P., and Tiede, D.M. SANS studies of structure and interactions of detergent micelles as applicable to

membrane protein crystallization. Amer. Cryst. Assoc., vol. 22, 75 (1994).

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I1-227
Shear Sensitivities of Human Bone Marrow Cultures

PRINCIPALINVESTIGATOR: Dr. Bernhard O. Palsson. Ph.D. University of Michigan

CO-INVESTIGATORS:

No Co-rs Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to reconstruct human bone morrow tissue ex vivo using the NASA bioreactor to

provide the culture environment for three-dimensional growth.

TASK DESCRIPTION:

The specific aims of this program are three:

I) To find optimal growth conditions lbr human bone marrow as a function of the supplied growth factors;

2) To develop a shear stress chamber that measures the shear stress sensitivity of human bone ma_ow cells;

3) To use the information gained from 1) and 2) to implement long-term, continuous bone marrow cultures in the

RWV.

TASK SIGNIFICANCE:

This study will focus on the elucidating role of three-dimensionality in bone marrow stem cell differentiation. The

development of a three-dimensional in vitro cell model will permit investigation into the biochemical signals that

triggers cell differentiation into various stages and subtypes of human blood ceils. It also will permit the

investigation of the role of three-dimensionality in extensive cell to cell contact and exposure to growth factors.

PROGRESSDURING FY 1994:

Conditions for the expansion of adult human bone marrow mononuclear cells in the rotating wall vessel (RWV)

have been established. Total cell numbers and the number of progenitor cells increase over time by a factor of

10-20 fold. Shear sensitivity of the cells does not hamper growth of these ceils. At present, it is unknown whether

stem cells are maintained or if they expand in number in the RWV. This issue will be investigated in the coming

year.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS S_dents: 0

PhD Student: 2

TASKINITIATION:11/92 EXPIRATION: 11/95

PROJECTIDENTIFICATION: 962-23-01-09

NASA CONTRACTNO.: NAG9-652

RESPONSIBLECNTER: JSC

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11-228
I|. MSADProgramTasks-- Ground-based Research Discipline: Biotechnology

Micro wavitt¢ Crystallization of Avian E£,£, White Ovostatfn

PRINCIPALINVESTIGATOR:Dr. Marc L. Pusey NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

D. Carter NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The rese_crch objective is designed to study the ovostatin from the standpoints of iL_suitability as a model protein

for protein crystal nucleation and growth mechanisms, the bio-mechanic.,d movements which apparently R)rm the

basis of its inhibitory activity, and using it as a means of studying the a,M group of proteins. Further, the

intention is to develop the crystallization conditions to be tried based upon studies of the physico-chemical

parameters, such Ks soh]bility phase behavior and observed nucleation kinetics. This will be our first demonstration

protein for the application of what is being learned about the crystal growth of macromolecules.

TASK DESCRIPTION:

The study of ovostatin is of interest for several reasons. This protein is attractive as a model for protein crystal

nucleation and growth studies. Crystals can be easily and rapidly grown in bulk solution. With a minimum step

height of 25-34 rim, surface features should be readily detectable in real-time using intefferometric techniques,

allowing direct observation of the crystal growth process. The large size would facilitate protein crystal nucleation

studies using light scattering methods. Practic_dly, ovostatin can be easily purified in large quantities, requiring

about 6 dozen hen egg whites/gram of protein. Material purified has been stable lot prolonged periods (over four

months) during crystallization trials and has been kept for over one year as a lyophilized powder. Finally, there is

the similarity between it and a,M. Currently, the only structural information extant is from electron microscopy

studies of isolated molecules.

Task 1: Preparation of ovostatin to 1/94 lot protein to be used in flight experiment(s). Large scale protein

purification will be continuous for the duration of the project. This material will be used to establish the reference

ground-based crystal qu_dity against which future flight crystals will be measured. Ovostatin prepared in this

laboratory will be made freely awtilable to other researchers wishing to study it.

Task 2: Screening of crystallization condition m 7/93. The best cry,stallization conditions determined at this time

will be used for future flight experiment(s). These conditions will then be used for the final solubility diagram

determinations to be used in designing the flight experiments.

Task 3: Establishing baseline crystal quality. Multiple data sets will be acqutred using the x-ray diffractometer.

These will be used to establish the bttseline ground-grown crystal quality.

Task 4: Studies of ovostatin. These will last lor the duration of this project. These will be done using the

instrumentation developed in the laboratory for the study of the protein crystal nucleation and growth processes.

TASK SIGNIFICANCE:

Any knowledge gained about ovostatin based on crystal structure analysis would advance the overall knowledge of

this l_nily of proteins.

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lI. MSADProgramTasks-- Ground-based Research Discipline: Biotechnology

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PROGRESS DURINGFY 1994:

Previous microgravity protein crystal growth experiments have used vapor diffusion, tree interface diffusion, and

dialysis techniques with most being done using vapor diffusion. Littke and John, using free interlace diffusion,

reported a 103 volume increase/dr beta-Galactosidase over crystals grown on Earth. In vapor diffusion experiments,

at least three proteins have shown significantly improved diffraction resolution over any of the crystals grown on

Earth, despite the fact that, because of short flight durations, crystallization conditions have had to be optimized for

rapid nucleation and growth, i.e., the temporal conditions were more favorable for lower quality crystals. Current

experiences are that ovostatin crystals nucleate and finish growing within a one- to three-day period. The process

will have to be slowed down to fit better within the timeframe tbr a typical microgravity PCG experiment, ZLs

opposed to the usual case where the crystal growth process must be speeded up. Based on the ovostatin crystal

currently grown, there is considerable room Ior improvement in both crystal size and diffraction resolution.

Ovostatin purified in this laboratory has now been supplied to lour other research groups as a test material. Dr.

William Wilson (Mississippi State University) has Ibund a dramatic dimerization-tetramerization behavior at low

ionic strength. This has led us to an investigation of ovostatin activity vs structure which has been carried out by a

mummer faculty (Dr. D. Moriarity, UAH). Ovostatin crystallizability has been tbund to be very sensitive to the

purification procedure and materials employed. We are currently supplying ovostatin to the laboratory of Dr. David

Blow (Imperial College) tor extensive crystallization trials which we hope will lead to a preliminary structural

determination.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PbD Students: 1

TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-23-08-26

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC

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II. MSADProgramTasks-- Ground-based Research Discipline: Biotechnology

u t _1 _ tit _11 it i 1 Ii 1is i ¢ Is iii I s i1_ s l iii i s s 1 ii i sl s s_s s s s 1 Is i s 11 s_ 1111 i_ 1 i_ 1111111 s 11 s Ii s ii iIIi ii 1111 it 1 ii 11 I_ 1 i_ 11.11 _11 ii iii 1 i ll II 11111 i ii _1 _ 1.11 iii i i 111 _ 1 ii1 ii 1 ii 1 i ll i_11.1 iii 111 i ss 11111 iii ii iit I1 i_slsll 11111 s i iiiii isl 1 i* _1111.1111_ 11 _111 ii _ ii

Study of Crystallization and Solution Properties of Redesigned Protein Surfaces

PRINCIPAL INVESTIGATOR:Prof. David C. Richardson Duke University Medical Center

CO-INVESTIGATORS:

M. Hecht

K. Gemert

J. Richardson

Princeton University

Duke University Medical Center

Duke University Medical Center

TASK OBJECTIVE:

The objective of this work is to determine what combinations of protein surface features and solution factors best

promote the growth of highly ordered protein crystals and to seek strategies for improving control over the process.

The experiment design is to make detailed analysis of crystal contacts in Cytochrome B562, construct a planned

series of mutations at those crystal contacts study crystal growth and solubility properties of the mutant proteins

study resultant crystal order and use the results to further refine analyses, hypothesis, and test mutants.

TASK DESCRIPTION:

High-resolution x-ray crystal structures of proteins are the backbone of academic and industrial research eftorts to

understand and control the detmled functional properties of these important molecules. Many such studies are

stymied, either by lack of crystals ",altogether or by crystals whose degree of order is inadequate to show details at the

level of resolution needed.

Two sets of factors jointly influence the growth of ordered protein crystals: the atomic-level details of the protein

surface, including flexibility and bound waters; and the solution conditions, including concentration and identity of

precipitants and other components, pH and ionic strength, temperature, interactions at solid or liquid interfaces,

vibration, convection currents, etc. Traditionally, the protein surface was not variable except by trying different

species, and the only strategy for solution conditions was simply trying as many vanations as possible. The most

general conclusion was that what worked for one protein was likely to be different than what worked for another.

Recently, however, there has been support and encouragement, largely led by NASA, lbr scientific study of the

process of crystallization. The most notable single result so tar has been the demonstration that growth in

microgravity can produce significantly better-ordered crystals for many proteins, presumably because of the absence

of convection currents at the crystal surface. The absence of convective currents, in turn, allows for the increased

effect of random diffusion of the protein molecules at the crystal surface and for the increased effective binding

energy of the protein molecule to the growing crystal. Both of these are presumed to lead to more accurate and

more stable attachment of the protein molecules to the crystal, and thus a better-ordered crystal.

Three to four mutants will be studied per year. Each study will involve computer-aided graphics studies of crystal

contacts and design of mutants, genetic engineering of mutants, protein purification, crystallization expertments,

crystal solubility determinations, face growth rate measurements, calorimeteric measurements of crystal growth, and

evaluation of crystal diffraction.

TASK SIGNIFICANCE:

The research aims are to contribute to the scientific understanding and the practical improvement of protein crystal

growth by tying together a series of designed mutations at known crystal contacts with the changes in

crystallization behavior and parmneters. There are several logical levels at which the results of this research should

be useful.

A research study of the relative strengths of the binding of protein molecules into their crystal is important tot

understanding which factors are improved in microgravity, whether the growth cessation phenomena can be

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II. MSADProgramTasks-- Ground-based Research Discipline: Biotechnology

alleviated in normal gravity, and how changes in crystal contacts can improve the overall order of protein crystals.

A detmled study of protein crystal contacts and their specific effects may also help in the future to sort our

influences on nucleation of protein crystals versus later growth. This research is designed to collect two

overlapping but distinct types of information: what specific side chain changes will strengthen or weaken a contact

for a particular crystallization media; and what contact strength is opttmum, relative both to the other contacts and

to the diffusion and convection conditions. Such inlormation will surely aid in future rational control of the

crystallization process.

PROGRESSDURING FY 1994:

The study of the solubility of wt-B562 crystals (grown under 3.5 M PO4, pH 6.8) continues under a variety of

buffer conditions, additivies and temperatures. A large set of proteins with random mutations to turn C (residues

glu-81, gly82, lys+83 wt) were generated, and 39 were sequenced (Hecht lab). The sequenced proteins were

characterized by spectroscopy, CD and denaturation studies. From this set, eleven proteins were chosen lbr

additional crystallization studies. First, mutant LGR-B562 has been found to grow diffraction quality crystals from

3.375 M PO4, pH 6.8, 1% MPD. Approximately 100 mg of LGR-B562 has been purified to begin solubility

measurements. Additionally, approximately 20 rags of each of the other ten proteins has been purified, and initial

crystallization trials of each have been analyzed. One, LAA-B562, has resulted in large diffraction quality crystals,

at conditions similar to wt-B562 (3.75 M PO4, pH 6.0). Two other proteins (RGM-B562 and SSR-B562) have

resulted in small, yet potentially diffraction quality crystals, in conditions neighboring that of wt-B562 (3.75 M

PO4, pH 6.0, for both). Four other mutants grew small crystals, either plates or rods, in the presence of needles,

while the remainder of the mutants formed needles or microcrystallin precipitate.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 8/93 EXPIRATION: 8/96

PROJECT IDENTIFICATION: 962-23-08-22

NASA CONTRACT NO.: NAG8-966

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Richardson. D.C. "Redesigning protein surfaces and crystal contacts." Poster presented at the Duke University Medical

Center Biochemistry Retreat, Beaufort. NC. November 6-8,t994.

Richardson. D.C. "Study of crystallization and solution properties of redesigned protein surfaces." NASA Protein Crystal

Growth Principal Investigator Planning Meeting, Panama City, FL, April 22, 1994.

II I II I I I I I I I I I I n i I I I i i I I I i i I iI II I I I I I I I I I I Ii i I I I I I I I I I i I Ii iI I I i i i I I I I i iI I I I I I I i I i i I I I i iI I I i i I I i II I I i I I I I i I i I iI I I I I I I I i i I II I II i i I I I I i I I I I I I I i I I II I I i I Ii i i I I I I I i II I I II i I I I II I Ji I I I I I I I I i l I II I I i i I I I i i i i i I I I I I i i i i i II I i i I i i I I i i i i I I I i i I I I I II I Ii i II i i I i i

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II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

_l_|_Hi"_"I_non_n1_e_j_"_|ii_"_"_i_j_HiHHHi_ui_ioH"v"i"_"_"_"_N_"_"_"_"_"n_|n;_|_n"_i_i"nii_l_n_Hi"n .,l,J H a,l.n,lllll,,ll,,.,._Hl,,ll,.i.l,|l,,i,H ,_ll,l.ll.,I.,,,lu,

Convective Flow Effects on Protein Crystal Growth and D(ffraction Resolution

PRINCIPALINVESTIGATOR:Prof. Franz E. Rosenberger University of Alabama, Huntsville

CO-INVESTIGATORS:

L. Monaco University of Alabama. Huntsville (UAH)

TASK OBJECTIVE:

This research aims at developing a detailed understanding of

• the nucleation and growth mechanisms involved in the crystallization of globular proteins,

• the formation mechanisms of structural and compositional nonuniformities (defects) in protein crystals and their

dependence on growth conditions, and

• the dependence of x-ray diffraction resolution of protein crystals on detect types and concentrations and, thus, on

crystallization conditions.

TASK DESCRIPTION:

We seek to establish, for select proteins, a correlation of well-defined solution conditions (purity, pH. buffer,

precipitant, supersaturation, temperature, and bulk transport) with nucleation and growth behavior during

crystallization, and the x-ray diffraction resolution of the resulting crystals.

Towards the above goals we are pursuing the following tasks:

• Characterization of the purity of protein solutions by gel electrophoresis. Preparation of highly homogenous

protein samples by high pressure liquid column chromatography.

• Studies of protein interactions and aggregation in under- and supersaturated solutions by static and dynamic light

scattering.

• Determinations of the precipitant repartitioning between solutions and growing protein crystals, using atomic

absorption and optical spectroscopy, and ion selective potentiometry.

• In-situ studies of the protein growth morphology and kinetics, with and without forced solution flow, by

high-resolution microscopic interferometry.

• Numericai modeling of diffusive-convective mass and momentum transport in geometries characteristic of protein

crystallization on Earth and in space, using experimentally determined precipitant repartitioning and growth kinetics

data.

• Measurements of protein/precipitant diffusivities in saturated and supersaturated solutions, employing a novel

interferometric technique that requires only small solution volumes.

• Measurements of the kinematic viscosity of supersaturated protein solutions, with a capillary flow technique.

• Determination of protein solubilities as a function of precipitant concentration, pH and temperature, using a

miniaturized optical scintillation technique.

• Characterization of the structural quality of selected crystals by x-ray diffraction and topography to reveal the

influence of kinetics and transport effects.

TASK SIGNIFICANCE;

The pharmaceutical industry, needs protein structure information to facilitate rational drug design. However, many of

the currently available protein crystals are too imperfect to yield detailed structure informauon. The reasons Ior this

low crystal perfection are not well understood. Interestingly, crystallization experiments in space have led to

significant improvements in crystal perfection for some proteins. Again, the physical mechanisms for this are not

clear. Our research aims at clarifying the connection between the magnitude of gravity present during protein

crystallization and the resulting crystal quality. This insight is expected to lead to the design of protein crystal

growth techniques that result in larger and more perfect crystals.

II-233
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

in"_ao_oi;_o_o_o!_no|_I_o|_"_o_n_o_n_o_n_u_nI_n_;n"i"_u_I_io_j4_i_oI1H_Ho_ao_n_Ini_aun_inH_on_H_uno_nI_n_ "nn_n_H_n"_a_i_o_no_t_n|_IIloI_o|_o_|_H_m_oo_i8_o_no_I_on_|n_I_o

PROGRESSDURINGFY 1994:

Our electrophoretic measurements revealed that significant amounts of high molecular weight protein impurities

exist in 'all commercial lysozyme stocks. These stocks are widely used without further purification in protein

crystallization studies. The removal of these impurities, which appear to influence most kinetics and repartitioning

processes, is being pursued with fast protein liquid chromatography.

Simultaneous static and dynamic light scattering measurements were pertormed on buffered solutions with lysozyme

solutions of various protein and NaCI concentrations. Contrary to most earlier work, the lysozyme diffusivities

were found to either increase or decrease with lysozyme concentrations, depending on the salt concentrations. The

corresponding static light scattering intensities show opposite dependence on lysozyme concentration. These data

are compatible with concentration-dependent changes of monomeric interactions. At the same time, these findings

appear inconsistent with earlier claims of the formation of small protein aggregates prior to nucleation.

The high-resolution microscopic investigations of lysozyme growth morphology and kinetics without torced flow

have revealed several novel phenomena. Depending on the impurity content of the solution, the growth step density

is either higher or lower at the periphery of a crystal facet than in its center. We also found growth kinetics

oscillations even at stable growth temperatures. These oscillations, which increase in amplitude with

supersaturation and crystal size, are associated with the formation of compositional inhomogeneities. These

phenomena form the tirst indication tbr mechanisms by which bulk transport conditions and, thus, gravity could

influence the protein crystal perfection.

The repartitioning of Na ÷ and CI ions between lysozyme solutions and crystals was investigated for a wide range of

crystallization conditions. A nucleation-growth-segregation model was developed to interpret the large body of data

in a unified way. The results strongly suggest that lysozyme crystals possess a salt-rich core with a diameter on the

order of 10 [.tin. These results are corroborated by white beam x-ray topographs (obtained on our crystals by V.

Stojanoff at the Brookhaven National Laboratories) which show an accumulation of defects in the crystals' historical

center. Further support tbr coring comes from our preliminary investigations of compositional inhomogeneities on

cross-linked, microtomed crystals with scanning electron microscopy and energy dispersive spectroscopy. In

addition it appears that the high molecular weight impurities preferenwally partake in the coring. Although these

findings have to undergo further scrutiny, they suggest some/K-reaching connections between protein crystal

perfection and crystal growth conditions.

A realistic numerical model for diffusive-convective transport in lysozyme crystallization has been completed. The

results indicate that even in the small crystallization cells typically employed, protein concentration nonunilormities

and gravity-driven solutal convection can be significant. The calculated convection velocities are of the same order

of magnitude as those tbund in earlier experiments. As expected, convective transport enhances the growth rates.

However, even when diffusion dominates mass transfer, i.e. at zero gravity, lysozyme crystal growth remains

kinetically limited. The salt distribution in the crystal is predicted to be nonunitorm at both 1 g and 0 g, as a

consequence of protein depletion in the solution.

To provide realistic input/br the modeling, and to link light scattering results with macroscopic diffusivity data, an

intefferometric diffusivity measurement setup has been completed. This setup requires only small (protein) solution

volumes and is accurate to better than 1%, as shown by extensive tests with NaCI solutions.

Also in support of the numerical modeling, the viscosity of a large number of lysozyme solutions was monitored

over time with a temperature controlled Cannon-Fenske viscometer under conditions which lead to crystallization.

Changes in the kinematic viscosity of aqueous solutions by 1% could be detected. However, none of the protein

solutions studied showed a change in kinematic viscosity as the solutions aged before crystallization. This indicates

the absence of a significant concentration of large clusters in lysozyme solutions prior to nucleation.

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II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

anqnuon n| l uo I I gnaool noI aooI ooa ooIs| I olo aolg ooi oo I aouaoolao iug ooaI oo uolnH aan aauaaunin al ugloaon aol I al aoil ooI gool go ogoI I aI gon ai oi ao! I uoi aooI ooi joI aolg ooI ooi nooIouaoagouaoaa oaa_a uoo i uf i ao I u_I ol oaoooonllo i anoao! i uoi aoo oooagu8uoi aI oI I oi ani aooaolaoo i

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 2/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-23-08-23

NASA CONTRACT No.: NAG8-950

RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Fredericks. W.J., Hammonds, M.C.. Howard, S.B., and Rosenberger, F. Density, thermal expansivity, viscosity and

refractive index of lysozyme solutions at crystal growth concentrations. J. Cryst, Growth. vol. 141. 183-192 (1994).

Rosenberger, F. Boundary layers in crystal growth. Prog. Crystal Growth Charact.. vol. 26, 87-98 (1993).

Rosenberger, F. Short duration low-gravity experiments - time scales, challenges and results. Micrograv. Sci. Technol,,

vol. VI, 142-148 (1993).

Presentations

Rosenberger, F. "Interplay between anisotropic interface kinetics and nutrient bulk transport," Plenary lecture at the

Annual Conference of the German Mineralogical Society. Freiberg. Germany. September 17-23, 1994.

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11-235
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

o o a oI o o n u i | u _ o no i ! o I =* u u o o I o | a o o t I o i n o I u o I g oi o i ! I I i t a | | i u _ | a i o I uo oI i u a o o u o o i ! o oa u i; o o u o o a o n uo Iu o I a o I a o I uI oI o | u o I a o I I o ! au o o o o _ g o o n s I o I i| | | i llu a g | _ o o i o o ii uo i i o i o o i I mi | o n lln u _ i a o i o o o o i! o o I _ _ o a o o aI I o o i o t I | a io o _ o n i o o I o o Io _ II o n n Do u * I I | _ oo o o a o i i _ IID i u

Enhancement of Cell Function in Culture by Controlled Aggregation

PRINCIPALINVESTIGATOR: Prof. W. M. Saltzman Johns Hopkins University

CO-INVESTIGATORS:

Frof. K. Leong Johns Hopkins University

TASK OBJECTIVE:

Cell-cell contact within tissues is fundamental to the regulation of cell differentiation and function. Cell

aggregates, lormed in vitro and maintained in culture, have been shown to maintain many of the functions of the

native tissue. The main objectives of this program are: i) development of methods for controlling cell aggregation

using bioactive polymers and polymer microspheres and ii) systematic study of the function and behavior of

suitably aggregated cells in culture. The discovery of new methods lbr improving cell growth and function in

culture is critical to the development of hybrid anJficiai internal organs and mammalian cell bioreactors.

TASK DESCRIPTION:

To achie ," these goals, we have formulated the following specific objectives/or a three-year period of study:

1; Synthesis of water soluble polymers/or controlling cell ag_egation. We will synthesize water

soluble polymers with bioactive groups that are specifically recognized by certain ceils and use these

multifunctional polymers as molecular nuclei to initiate and control cell aggregation. We will use these polymers

to control aggregation by adding them to gently agitated or quiescent suspensions of single cells; this technique will

produce small cellular aggregates (< I0 cells, diameter< 100 mm). By altering the properties of the polymers and the

conditions of aggregauon, we will identify approaches tor obtaining cell aggregates of different size, polydispersity,

and morphology. We have demonstrated the feasibility of this approach using N-acetyl glucosamine (specific lor

chicken hepatocytes) attached to vinyl polymers.

Objective 2: Fabricauon of polymer microspheres for earner-assisted cell aggregation. We will fabricate

microspheres containing encapsulated, soluble mediators of cell growth and function. We will use the microspheres

to create larger aggregates with a cenu'al polymer core. We have also demonstrated the fea.sibility of this approach

using microspheres composed of vinyl polymers and cultured hypatocytes.

Objective 3: Development of methods for culturing cell aggregates under unit gravity. In preliminary studies, we

have encapsulated hepatocytes and hepatocyte aggregates within gels of type I collagen, cultured these encapsulated

cells, and examined subsequent cell growth, function, and viability. We will test gels of collagen under different

hydration conditions to find an optimal experimental system for maintaining ceils in an aggregated and suspended

state in the laboratory. The gels will be used to suspend aggregates created with water-soluble polymers and

microspheres. To develop model culture systems representing both liver and neuronal tissues, we will use primary

cultures of hepatocytes, primary cultures and fetal brain ceils, neuroblastoma cell lines, and the PC12 cell line.

Obiective 4: Measurement of cell function under different aggregation conditions in gel culture. We have already

developed methods of monitoring cell growth and metabolism in culture by measuring cellular protein, DNA, and

lactate dehydrogenase (LDH) content. We have also developed methods for monitoring cell function in culture by

following albumin and uric acid secretion (/'or hepatocytes) and expression of specific enzymes and responsiveness

to nerve growth factor (for PC12 cells). Using the optimal experimental system, defined in specific objective 3,

we will systematically examine the function of cell aggregates in culture. Aggregates will be cultured under a

variety of conditions including i) conventional static culture, ii) static culture with aggregates suspended within gels

of extracellular matrix molecules, and iii) microgravity culture of aggregates within the NASA rotating-wall

bioreactors.

Objective 5: Preparation of experiments for evaluation under micro mravity conditions. In specific objectives 1

through 4, we will have identified the important variables tot controlling cell aggregation and function in aggregate

culture. In the final stages of this project, we will design methods for developing physiologically realistic cell

aggregates under microgravity conditions and tbr testing the influence of aggregation on cell function in suspension

culture under microgravity in space.

i noi! i !; o|o oI nal ua* I DOI oi *o uo! ol DOlDOI IDa DID Dill | | II OOI DOOIll oai iI I oq| oI Do! DOI Dolad ill ooooI1 lull I DOI OOO! O!|O I O01O01hi! OOOI DOI al| ! l Ol alll OOil ! I I |DILl DO1| OIl ! O I! ODOO! * I ! |! ! OI ! OIlll I D! !|l! Oil ODI Ilia I Ol DOI DOOOOI !OgI DOOOI O01 OIl nol oI o! o* ! ol ! o! ogI * nI ou! | DoI | o

!1-236
l|. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

i.illa.aoll.lllllll .llOlllllllOlalUlOlll0Uall|lllalllll j_o_o_l_I_;_a_o_I_I_"I"i_Ia_$_a_j_aulto_a_I_n__u_ou_u_o_l__u_

TASK SIGNIFICANCE:

These studies are uniquely suited tor study in microgravity. First, cell aggregation m zero gravity will be driven by

migration and diffusion rather than by forced collisions as is necessary on earth. The resulting aggregates may be

closer to those found in tissues, since tissues are formed by migration and selective adhesion. Second, gentle

suspension culture techniques can be used to culture the aggregates in microgravity. By the end of the period of

laboratory study prol_)sed here, we will have developed cell aggregation techniques appropriate lor testing under

microgravity conditions in space.

PROGRESSDURINGFY 1994:

Objective 1: We have synthesized several water-soluble molecules as molecular nuclei for cell adhesion. These

molecules are based on poly(ethylene glycol) with bioactive peptides, NH_-Gly-Arg-Gly-Asp (GRGD) and

NH3-Gly-Tyr-Ile-Gly-Ser-Arg (GYIGSR), gra.t'ted to the termini. We have developed covalent coupling methods for

attaching these peptides to PEG with a variety of molecular weights (5,000 to 30,000) and to polystyrene

microspheres (0.1 to 10 ram). We have used quantitative cell adhesion assays to determine the best peptides for

conjugation. We have examined the kinetics of cell aggregation of a number of important cell types (including

neural cells and cell lines, fibroblasts, and genetically engineered fibrohla_sts). We are developing methods for

examining cell function for aggregates maintained in culture. The first report in this work was published this year

IDol, Belt, and Saltzman, 1994) and other publications are in progress.

Objective 2: We have synthesized polystyrene pol_ners modified with carbohydrates and peptides at the surface. A

manuscript describing this work was published this year (Gutsche, et. at., 1994). These unique polystyrene-based

polymers can be formed as microspheres, and cells attach and grow avidly to these novel microcarriers. We have

developed similar methods for coupling peptides to polystyrene supports with a range of sizes.

Objectives 3 and 4: We have developed methods for culturing and forming aggregates under unit gravity. A

manuscript that was recently accepted for publication is appended. (Krewson, C.E., Chung S .W., Dai, W., and

S',dtzman, W.M. Biotechnology and Bioengineering 43:555-562 (1994). We have adapted these methods for

producing aggregates within the NASA rotating-wall vessels.

Objective 5: Only applicable to the third project year.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 11192 EXPIRATION: 11195

PROJECT IDENTIFICATION: 962-23-01-I0

NASA CONTRACT No.: NAG-654

RESPONSIBLE CENTER: JSC

BIBLIOGRAPHIC CITATIONSFOR FY 1994:

,lournals

Dai, W, Belt J. and Saltzman. W.M. Cell-binding peptides conjugated to poly(ethylene glycol) promote neural cell

aggregation. Bio/Technology, 12. 797-801 (1994).

Gutsche, A.T.. Parsons-Wingerter P. Chand. D. Saltzman, W.M. and Leong K.W. N-acetylglucosamine and adenosine

derivatized surfaces for cell culture: 3T3 fibroblast and chicken hepatocyte response. Biotechnology and Bioengineering,

43, 801-809 (1994).

Krewson, C.E., Chung, S.O. Dai. W. and Saltzman. W.M. Cell aggregation and neurite growth in gels of extracellular

matrix molecules. Biotechnology and Bioengineering, 43. 555-562 (1994L

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Saltzman, W.M., Belt. J. Dai, W. Krewson, C.E. Livingston. T. Parkhurst, M.R. and Shin, M. Synthesis of polymeric

substrates and characterization of cell-polymer interactions. 3ournal of Cellular Biochemistry Supplement. 18C, 240

(1994).

Presentations

Saltzman, W.M, Beaty C.E. Chung S.W. and Dause R.B.

Meeting, St, Louis. MO. November 1993.

"Polymers for stimulating neurite outgrowth." AIChE Annual

Saltzman, W.M., Belt J., Dai W., Krewson C.E., Livingston T. Parkhurst M.R. and Shin M. "Synthesis of polymeric

suhstrates and characterization of cell-polymer interactions." Keystone Symposium on Tissue Engineering, Taos, NM.

February 1994.

Saltzman, W.M., Dai W. Krewson C.E. and Parkhurst M.R. "Polymers for controlling ceil motility and aggregation." 1st

International Conference on Cellular Engineering, Stoke on Trent. UK, 12-15 September 1993.

11-238
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

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Culture qf Porcine islet Tissue: Evaluation of Microgravity Conditions

PRINCIPALINVESTIGATOR:Dr. David W. Scharp Washington University School Of Medicine

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

Porcine islet tissue is receiving new attention as an attractive, potential tissue for application in clinical islet

transplantation in patients with Type 1, Insulin-Dependent Diabetes Mellitus (IDDM). Recent clinical success of

islet transplantation into patients with renal grafts using human islets and standard immunosuppression

demonstrated that greater than one year islet graft function can be achieved off insulin therapy. As additional

patients are being transplanted to establish how many patients can achieve insulin independence and for what

duration, investigators are anticipating that the 4,000 human organ donors a year will be insufficient for the

[]umbers of potential transplants that can be achieved. Thus, adult porcine islet isolations are being developed. We

have developed an adult tx]rcine islet procedure but realize that the use of neonatal porcine islet tissue is more suited

for clinical application from a cost production viewpoint as well as from a safety viewpoint, since the neonatal

porcine islet tissue could be obtmned from gnotobiotic donors. While this seems ideal, there has not been any

reliable way to isolate neonatal islet tissue in any quantity nor any method to culture these islet cells. We have

recently developed a markedly improved method for the isolation and purification of neonatal porcine islet tissue,

but, have no reliable method to culture islet cells that can not only produce new islets, called pseudoislets, but also

take advantage of their inherent growth and maturation potenti',d prior to consideration of transplantation.

Learning of the microgmvitational culture system with low shear rate and the proven tmportance in producing other

tissue types from single cells developed by Dr. Glenn Spaulding (NASA JSC), he and I have established a new

collaboration that would combine our islet tissue.

TASK DESCRIPTION:

To accomplish these three objectives, we propose the following specific aims for the investigations:

1. To culture neonatal islet tissue by rotational, microgravitational and static methods to determine optimal ways

of lormation and preservation of functional pseudoisleks.

2. To examine the ability of cultured neonatal porcine islet tissue to develop and maJn_n differentiated islet

functional characteristics.

3. To determine the ability of optimally cultured porcine islet tissue to be successfully transplanted into diabetic

recipients.

4. To examine the replication potential of neonatal porcine islet tissue through culture manipulations. These

proposed studies combine the islet expertise with a method of rotational islet culture that has successfully formed

neonatal porcine pseudoislets with the microgravitational expertise with a specific low shear culture system that

seems ideally suited to the fragile neonatal islet cells. Successful completion of these proposed studies should

provide important results that will have considerable application in the islet field as well as in the field of

microgravitational studies important to future NASA objectives.

TASK SIGNIFICANCE:

The results of these studies will provide new information to three areas. The results will be tmportant to: 1) a

better understanding of the development of neonatal islet tissue, 2) NASA considerations of islet tissue as a

potential type of tissue for their microgravitational studies, and 3) islet transplantation for developing an effective

culture system lot this promising new source of islet tissue.

11-239
PROGRESSDURING FY 1994:

This project continues to utilize islet tissue isolated from 14 to 29 day neonatal pigs which have been surgically

'altered at three days of age and given teed enriched with potential growth factors to increase the beta cell production

and maturation for the 10-day to two week period prior to harvest. So far this year, we have performed twelve

separate experiments, each closely monitored at different stages by sampling/or DNA extraction, insulin

production, glucose utilization rates, insulin extraction, and histology evaluation.

Results show a two- to seven-told increase in the number of aggregates at two weeks of culture. Although glucose

utilization is fairly constant, there seems to be a maximum output of insulin at one week of culture. Final

viability testing shows functional islet tissue and a 95% viability by fluorescein diacetate staining. Recent studies

have been focused on varying the culture medium used, as well as varying the tissue and bead ratios. One of our

latest developments has to do with increasing the ability to process more tissue at a time, therefore cutting down on

the variabilities and increasing the yield per grams of tissue, allowing us to culture more aggregates from each

experiment.

Although in vitro testing has been a successful tool in monitoring the progress of our tissue survival and growth,

we have just recently begun to study the potential of this project with in viva growth of our neonatad tissue. We

are using the SCID (sever-combined immune deficient) mouse Ks a recipient model, in order to avoid any rejection

problems. The results of these experiments are too recent to draw conclusions but our expectations for this series

are high.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION:962-23-01-08

NASA CONTRACT NO.: NAG-653

RESPONSIBLECENTER: JSC

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11-240
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

Automation of Protein Crystallization Experiments: Crystallization by Dynamic Control of

Temperature

PRINCIPALINVESTIGATOR:Dr. Keith B. Ward Naval Research Laboratory (NRL)

CO-INVESTIGATORS:

W.M. Zuk

M.A. Perozzo

Geocenters, Inc./Naval Research Laboratory (NRL)

Naval Research Lalx_ratory (NRL)

TASK OBJECTIVE:

The goal of this research program is to develop a dynamic'ally-controlled crystallizaUon system (DCCS) in which

protein supersaturation is controlled by varying the temperature while crystallization is monitored by optical means.

This device will also be capable of being controlled telerobotically. The program intends to extend its

accomplishments in this area by continuing to enhance the DCCS, expanding the system to include multiple

crystallization chambers and incorporating more efficient and versatile systems for monitoring the progress of

nucleation and crystallization. A final goal of this prolect is to ascertain to what extent the technique of

temperature-controlled crystallization is applicable for protein crystallization.

TASK DESCRIPTION:

A study of a representative ,sample of weB-characterized proteins that have been successfully crystallized using other

methods is proposed. The temperature coefficient of solubility will be measured using the DCCS, and attempts to

prepare crystals in this apparatus will allow us to judge the general usefulness of this approach.

The proposed methods of research include further modifying the current design to incorporate video monitoring to

provide visual observation of growth volumes, to introduce dynamic light scattering, and to expand the system to

include multiple crystallization cells, each with separate temperature controls. Telerobotic control experiments will

continue using enhanced control software, and the results of the experiments will be aimed at defining the

capabilities and limitations of remotely-controlled crystallization protocols on space platforms in microgravity.

Collection of protein temperature solubility data will be enhanced by the development of more fully automated

software algorithms. The temperature of a sample is slowly changed step-wise until the level of scintillation signal

indicates that the crystallization phase boundary has been crossed. The temperature will then be recycled using a

finer step size until the solubility temperature of the sample is determined to within 0.1 °C. Although currently

some of this process is conducted manually, further development of the control software will completely automate

the process.

TASK SIGNIFICANCE:

This research is important in continuing the development of dynamically-controlled crystallization systems, provmg

the usefulness of dynamic control in conducting protein crystallization experiments in microgravity. This work

will also aid the current effort of other NASA-funded Principle Investigators in designing advanced crystallization

apparatuses. This system will also be used, while it is being developed, to explore whether temperature control of

supersaturation is a technique that can have wide applicability in laboratory-based protein crystallization.

PROGRESSDURING FY1994:

The DCCS has been miniaturized and redesigned to allow the use of crystallization solutions as small as 100

microliters. Temperature is controlled through the use of small thermoelectric coolers. The new device utilizes a

common miniature fluonmeter cell as the growth chamber, greatly easing the preparation and clean-up of

experiments. The system was also designed to permit easy integration of a miniature video camera for visual

observation of growth cells. Preliminary solubility and crystallization experiments have been conducted to

demonstrate the usefulness of the new apparatus. Control software is continually being refined and will soon allow

multitasking of procedures so that multiple experiments may be conducted simultaneously.

11-241
IL MSADProgramTasks -- Ground-based Research Discipline: Biotechnology

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STUDENTS FUNDED UNDER RESEARCH: TASKINITIATION:1/93 EXP_RATION:1/96

PROJECTIDENTIFICATION: 962-23-08-24

NASA CONTRACTNO.: H-O'7975D

RESPONSIBLECNTER:MSFC

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I1-242
Thermal Optimization of Growth and Quality of Protein Crystals

PRINCIPALINVESTIGATOR: Dr. John M. Wiencek University of Iowa

O0-1NVESTIGATORS:

E. Arnold Rutgers University

TASK OBJECTIVE:

The overall goal of this project is to control supersaturation at constant values during protein crystal growth by

varying the temperature in a predetermined (by simple theory) manner. Applying the theory requires knowledge

about specific physicochemical properties of the protein solution including the effect of supersaturation on growth

rates and the effect of temperature on protein solubility. Our specific goals for b-T94 were:

• Application of a temperature control strategy which mmntains constant supersaturation to the growth of

lysoz?ane crystals and comparison to traditional isothermal strategies.

• hwestigation of hatch isothermal calorimetry as a tool to determine lysozyme solubility as a function of

temperature by employing the Vau't Hoff equation.

• Construction of a video microscopy apparatus for determination of crystal growth rates and terminal size.

Work for the coming year will focus on the me&£urement of solubility and crystal growth rate lor human serum

'albumin as well as the assessment of the crystals grown by the developed strategies via xray diffraction.

TASK DESCRIPTION:

Three protein systems have been chosen for study: lysozyme, human serum albumin (HSA), and HIV reverse

transcriptase (R'I3. Each of these proteins have unique features that make them interesting. Lysozyme and HSA

represent fairly inexpensive and readily available proteins and will be model systems for investigations elucidating

the effects of growth rates on crystal quality. Once strategies that are optimal are available, such strategies will be

applied to the RT system as a realistic test case.

Experimental evidence suggests that larger and higher quality crystals can be attained in the microgravity

environment of space. Fundamental studies have attempted to measure and model the effects of gravity-induced

convection and sedimentation on the crystal growth process. However, the effect of growth rate on protein crystal

quality is not well documented. If the growth rate is controlled, how much time is required to allow for interfacial

attachment of the large protein molecule'? What is the impact of this "attachment time" on crystal quality? This

research effort is directed at measuring the effects of crystal growth rate on the ability of crystals to diffract xrays.

We hope to link crystal quality to slow growth rates and discern "how slow is slow enough." In addition,

processing strategies will be developed which xray cry stallog-raphers can use to grow larger, high-quality crystals.

The investigation requires the measurement of protein (lysozyme, HSA and RT) solubility at two or more different

temperatures (typically 4 ° and 25 ° C) aa_d the growth rate at two or more different supersaturations.

Microcalortmetry is a potentially powerful technique to measure these and other (e.g nucleation) physical parameters

of the protein systems.

TASK SIGNIFICANCE:

Development of a systematic method of protein crystallization may lead to crystallization of previously

uncrystallizable proteins and add to current lmowledge of protein structure/function relationships. Knowledge of

detailed protein structure is essential for rational design of therapies and small molecule pharmaceuticals.

11-243
II. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

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PROGRESSDURINGFY 1994:

Material balances and kinetic rate laws were combined with solubility data to produce a temperature control

algorithm designed to maximize crystal size and maintain the crystal growth conditions in or close to the metastable

zone. Several assumptions were made in the construction of the temperature algorithm, the first being that of

constant growth rate. Because our experiments were performed in the reservoir of a temperature-controlled water

bath, it was not feasible to measure the crystal growth rate during the course of the experiments. Studies are

currently underway to measure the growth rate of crysta/s in situ, to determine whether the assumption of constant

growth rate was met in our experimental system. The second major assumption in the temperature control model is

that only one crystal is present and growing throughout the experiment. With the exception of the isothermal 4 °C

program, the predicted final size of the seeded samples corresponds closely with the measured average final size in

the seeded systems, indicating that this may not be a limiting assumption. Nucleation can "also be accounted for in

future studies by taking additional crystals into account in the mass balance. A third assumption is that the growth

rate model is dependent only on supersaturation. This model was used in the generation of tour temperature control

strategies tbr the growth of lysozyme crystals: curved (constant growth model), linear ramp, isothermal 20 °C, and

isothermal 4 °C. Both the linear and the curved temperature programs yielded large, well-formed crystals, The

isothermal 4 °C program also resulted in large crystals, but they were poorly formed due to the high initial growth

rates. The enthalpy of crystallization of hen egg-white lysozyme in two 0.05 M acetate buffers (5% NaCI, pH 4.6

and 3% NaCi, pH 5.2) was determined at 15 °C using isothermal calorimetry and was found to be -17.1 + 3.2

kcal/mol (5% NaCI) and -10.5 + 2.3 kcal/mol (3% NaCI). These values were found to agree within experimental

error with the enthalpy of crystallization determined from a Van't Hoff plot of solubility.

In this work, we have shown that the use of controlled temperature changes leads to improved size of lysozyme

crystals= and can limit nucleation in a crystallizing system. These temperature ramps must have a basis in the

physicochemical properties of the system (i.e.= solubility, enthalpy and growth rate kinetics). Perhaps the major

limitation in extending the use of this algorithm to other systems is the limited amount of physicochemical data

available for most proteins. However, our results show that there is some flexibility in the application of

temperature control, so that a linear temperature ramp may be just as effective as our "constant growth rate"

algorithm. This indicates that moderately accurate physical and chemical data may be required to generate an

appropriate temperature ramp. The use of calorimetric methods to auain solubility and enthalpic data may provide

another source of the necessary information. It is expected that as more inlormation becomes available, this type of

predictive temperature control strategy can be applied to a wide variety of systems, facilitating the growth of large,

single protein crystals suitable for X-ray crystallography.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 3

TASK INITIATION: 6/93 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-23-08-28

NASA CONTRACT No.: NAG8-975

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Schall, C,, Wiencek, J.M., Yarmush, M.L.. and Arnold, E. Lysozyme crystallization studies at high pressure, J, Cryst.

Growth, vol. 135, 548 (1994).

Presentations

Wiencek, J.M. "Production of protein crystals suitable for X-ray diffraction analysis: controlling growth rates via

temperature manipulations." Fall Colloquia, Chemistry and Chemical Engineering, Polytechnic University, Brooklyn,

NY, October 5, 1994.

Wiencek, J.M. "Efficient separation from dilute solution via driving force manipulation." University of Iowa, Iowa City,

IA, December 9, 1993.

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11-244
Wiencek. J.M. "Thermal optimization t_t protein crystal growth," NASA Protein Crystal Growth Conference, Panama

City Beach. FL, April 26. 1994.

Wiencek. J.M.. Schall. C.A.. Li. E.. and Arnold. E. "Measurement of enthalpy of fusion of lysozyme crystals by

calorimetry and application to maximization of crystal size." AIChE Annual Meeting. St. Louis, MO. November, 1993.
II. MSAD Program Tasks R Ground-based Research Discipline: Biotechnology

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Search for Dilute Solution Property to Predict Protein Crystallization

PRINCIPALINVESTIGATOR:Dr. W. W. Wilson Mississippi State University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The primary objective of the research is to discover a unique dilute solution parameter that universally and

unambiguously predicts protein crystallization.

Since most crystallographers will not have access to sophisticated laser scattering instrumentation, a secondary

objective of this research is to construct a simple laser scattering device that determines the universal predictor

values. The device will be miniaturized to work with sub-milliliter volumes and incorporate the latest optical fiber

technology tbr beam delivery and signal detection.

TASK DESCRIPTION:

Static, dynamic and electrophoretic laser scattering techniques will be used to carefully measure an array of

thermodynamic and hydrodynamic (not kinetic) solution parameters for each of a group of selected proteins dissolved

under crystallizing as well as non-crystallizing solvent conditions. The proteins chosen will have a wide variation

with respect to molecular weight and crystallizing conditions such as temperature, pH and crystallizing agent type

(inorganic salts, PEGs and other organics). The laser scattering solution parameters will be measured in the dilute

protein concentration regime, often 10-20 times below protein saturation.

The research approach is to obtain comprehensive measurements of the SLS, DLS and ELS parameters from a set

of selected proteins under both crystallizing and precipitating conditions with particular attention given to the dilute

solution regime. The selection of the proteins is significant, and some collaboration with protein crystallographers

will be required to totally define the set. Prior verbal agreement for such advisory collaboration has been obtained

from Marc Pusey and Dan Carter at Marshall Space Flight Center in Huntsville, Alabama, Pat Weber at Dupont in

Wilmington, Delaware, Alex McPherson at the University of California, Riverside, Franz Rosenberger at the

University of Alabama, Huntsville, and Charlie Bugg and Larry DeLucas at the University of Alabama,

Birmingham. Use will also be made of the Biological Macromolecule Crystallization Database compiled by Gary

Gilliland at the Center for Advanced Research in Biotechnology in Rockville, Maryland. Based on years of

experience in performing laser scattering measurements and on the man-power requested in the budget, a target

number of twenty proteins is projected for the set, corresponding to roughly one complete set of measurements per

protein per month. This amount of time accounts for protein purification procedures as well as repetitions for each

of the SLS, DLS, and ELS experiments.

TASK SIGNIFICANCE:

It is anticipated that a particular solution parameter (or combination of parameters) will be discovered that has

quantitative values within a reasonable narrow range for crystallizing conditions and values significantly outside that

range for non-crystallizing or precipitating conditions. If such a universal predictor can be proven, then its use will

have an immediate impact in the protein crystal growth community in general and microgravity research in

particular. The solution conditions for protein crystallization in a microgravity environment should be maximized

during ground testing so that a high probability for crystallization is achieved. Having a universal predictor will

allow crystallographers to fine tune existing crystallization protocol or discover new conditions to crystallize

difficult proteins.

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11-246
[I. MSADProgramTasks-- Ground-based Research Discipline: Biotechnology

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PROGRESSDURING FY 1994:

The focus of work during this period was investigating three laser scattering methods as potential diagnostics for

predicting solution conditions lavorable for protein crystal lization. One method, electrophoretic laser scattering or

ELS, has been found to be generally not appropriate for this work. We have determined that the resolution of ELS

for small proteins with molecular weights less than al'xmt 100,000 daltons is poor. ELS may be useful for studying

large particles such as viruses, but its applicability for protein crystallography is doubtful. Accordingly, our

emphasis shifted to static laser scattering (SLS) and dynamic laser scattering (DLS), both of which seem promising.

We have studied about fifteen different protein/solvent crystallization conditions by SLS and have found that a

thermodynamic solution parameter called the second virial coefficient, B22, seems to be a general predictor for

protein crystallization. DLS was used for some of the same protein/solvent pairs to determine if the diffusion virial

coefficient, KD, could also be used as a predictor. The results for DLS are not conclusive at this trine.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: O

MS Students: 0

PhD Students: 2

TASK INITIATION: 7/93 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-23-08-21

NASA CONTRACT NO.: NAG8-965

RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

George, A.,andWilson, W.W. Predicting protein crystallization _om a dilute soiution property. Acta Cryst.,vol. D50,

361-365 (1994).

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11-247
I|. MSAD Program Tasks -- Ground-based Research Discipline: Biotechnology

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Characterization of Solvation Potentials Between Small Particles

PRINCIPAL INVESTIGATOR:Dr. Charles F. Zukoski University of Illinois, Urbana-Champaign

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

A combined experimental and modelling eflbrt is used to characterize how variations in solvent chemical potential

alter the states of aggregation of colloidal particles.

TASK DESCRIPTION:

The objective of the FY94 program is to develop a combined density tractional theory, and Monte Carlo simulation

technique to describe the phase behavior of parucles where interactions are dominated by solvation lorces. In

addition, the role of solvent/particle interactions in creating hydrophobic attractions is explored. On the

experimental side, direct links are made between interparticle forces and phase behavior through measurements of

protein second vireal coefficients by light scattering and phase behavior as protein concentration is increased.

TASK SIGNIFICANCE:

Developing methods which reliably result in high quality protein crystals is of major technological significance in

the development of fun "damental understanding of biochemical phenomena and the expression of genetically altered

therapeutic proteins. In the work carried out here, new methods of controlling protein crystallization are explored.

The modelling effort seeks to guide the experimental program by providing understanding of the role of solvation

interactions in controlling the state of protein aggregation. The modelling effort has shown that the rarely

recognized variable of solvent chemical potential can be used to control protein crystallization behavior. The

experimental program is "aimed at developing methods of characterizing protein interactions as solvent chemical

potential is altered and demonstrating links with crystallization behavior.

PROGRESSDURINGFY 1994:

Substantial modelling progress has been made. Simulation studies show that variations in solvent chemical

potential can strongly influence how small particles associate and the strong influence of solvent/particle

interactions. Experimentally, light scattering techniques have been used to determine the second vireal coefficient,

B2, of lysozyme molecules as a function of pH and ionic strength. B2 is a measure of the strength of interparticle

torces trending from positive to negative as the interactions pass from repulsive to attractive. Linking B: to

conditions resulting in crystallization remains a central task in FY95.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 6/93 EXPIRATION: 6/96

PROJECTIDENTiFiCATiON: 962-23-08-27

NASA CONTRACtNO.: NAG8-976

RESPONSIBLECENTER: MSFC

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11-248
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Douglas L.J.. Lupkowski. M,. Dodd, T.L.. and van Swol. F. On the role of solvation forces in colloidal phase transitions,

Langmuir, vol. 9. 1445 (1993).

Frink. L.J.D.. and van Swol. F. S_lvation forces and colloidal stability: A combined Monte Carlo and density functional

theory approach. J. Chem. Phys., vol. 100. 9106 _1994).

Presentations

Frink, L.J.D., Zamora, P., van Swol, F. and Zukoski, C.F. "The freezing of colloidal suspensions in confined systems."

8th International Conference on Surface and Colloid Science, Adelaide. Australia. February, 1994.

II-249
|I. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

Effects of Energy Release on Near Field Flow Structure qf Gas lets

PRINCIPALINVESTIGATOR:Prof. Aiay K. Agrawal University of Okl',daoma

CO-INVESTIGATORS:

S.R. Gollahalli University of Oklahoma

TASK OBJECTIVE:

The primary objective of this research is to understand how buoyancy affects the structure of the shear layer, the

development of fluid dynamic instabilities, and formation and characteristics of the coherent structures in the

near-nozzle regions of burning gas jets. The secondary objective is to understand the role of buoyancy in the flame

lifting and reattachment process, evaluate the scaling behavior of diffusion flames, and aid in the development of a

theoretical model by providing quantitative temperature data throughout the flame in the absence of buoyancy

effects.

TASK DESCRIPTION:

The initial phase of this project involves the visualization of near-t-mid flow structures in cold jek_ and nonsooting

flames at the same flow conditions or the same jet exit Reynolds number, allowing the effects of energy release on

these structures to be identified by comparison. The experiments will use hydrogen and hydrogen-inert gas

mixtures as the fuel with air as the oxidizer. Energy released in the flame will be controlled by varying the

hydrogen mole traction in the jet stream. Attached flames, lifted llames, and flames in the transition region

between these two extremes will be studied. Expertments for 'all cases will be conducted in both normal and reduced

gravity.

TASK SIGNIFICANCE:

The phenomena cx:curring near the exit of a gas jet nozzel determine burning characteristics and the rate of pollutant

generation. The effect of buoyancy on these processes is poorly understood and hence it is difficult to model when

designing commercial combustors. This project will study the fluid dynamics of turbulent gas ,jet combustion,

applicable to commercial combustors of this type and may lead to higher efficiencies and lower pollution generanon

levels.

PROGRESSDURING FY 1994:

Since the award of this grant in June 1994, laboratory space was acquired and safety procedures were established to

begin this project.

Computer software for the generation of rainbow filters was developed in conjunction with Dr. Fletcher Miller,

Case Western Reserve University, and NASA LeRC equipment and personnel. The filters were printed on a high

resolution Polaroid digital film recorder, which is capable of producing 35 mm slides. These slides are being used

with a schlieren system interfaced with a 342CD color camera and a personal computer equipped with image

processing software.

Concurrently, experiments were conducted using hydrogen as the fuel at atmospheric pressure to determine an

appropriate size of the nozzle for drop tower experiments. The accompanying fuel supply system and test section

for both atmospheric and low pressure studies were designed and fabrication has been initiated.

i i i i I i I I II i I I I i i ii I i i i i II i i | i i i I i Ii i ii i i I i I i i Ii I ii i i ! i i I i I i i ¢i ii iI I I I i i I I i I ! i i i ii i i i i I i i I ! i i i ii ! I i t DI _I I ¢I II I I I I I I II I II I II I I I I II I I I I II I I I I I I I I I I I I I I I I II I I I I I I I I I I II I I I I ! I I I I I I I II I I I I I I I I | I I¢I I ¢I I | I I I I I II I I I II i II I III I II Illtl II I I II I I I I II II I I I I I I I

11-250
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 5/97

BS Students: 2 PROJECT IDENTIFICATION: 962-22-05-57

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 0

11-251
Radiative Extinction qf Diffusion Flames

PRINCIPALINVESTIGATOR: Prof. Arvind Au'eya University of Michigan

CO-INVESTIGATORS:

Prof. I.S. Wichman Michigan State University

TASK OBJECTIVE:

The objective of this program is to quantify the conditions under which a stabilized, laminar diffusion flame will be

extinguished by radiative heat losses from flame-generated particulates (e.g., sou0 that drain the chemically released

energy lrom the flame. These tests must be conducted in rnicrogravity because radiation-induced extinction may not

be possible under norm'd-gravity conditions where buoyancy-generated convection would sweep the radiating

sources upward and away from the flame.

TASK DESCRIPTION:

The program is to have simultaneous experimental and theoretical efforts. Experimentally, normal-gravity tests

using a quasi-one-dimensional counterflow diffusion flame burner will be studied to quantify soot production and

oxidation rates and their optical properties. These data are needed both for the formulation of the reduced-gravity

testing and for the development of theoretical models.

Subsequent reduced-gravity testing is to be pursued in the 2.2 second drop tower at NASA Lewis Research Center,

where a laminar diffusion flame is to be stabilized about a spherical porous burner. In these tests the local fuel

concentrations will be varied by the introduction of inerts into the fuel-flow stream. Measurements of flame

temperature and radiation flux will be used for comparisons with theory.

A numerical model will be developed to simulate the reduced-gravity experimental cord'_guration, and will include a

chemical-kinetics-model and an emperical model of the production and consumption of soot particulates. A model

of the radiant emissions from the flame, associated with the particulates, will be developed.

TASK SIGNIFICANCE:

The microgravity flames will demonstrate the concept of radiative extinction in stabilized/]ames, distinct #urn the

case of spreading diffusion flames. This mechanism of extinction is likely unique in microgravity, and thus may

have application to fire safety aboard orbiting spacecraft.

PROGRESSDURING FY 1994:

During the year the following major accomplishments were achieved:

1. Several modifications to the 2.2 second drop tower apparatus were completed, The modifications include: 1) a

new ignition system consisting of a hydrogen flame stabilized around the spherical burner then switching the fuel

flow ti'om hydrogen to the test fuel; 2) three thermocouples to measure the burner surface and two gas-phase

temperatures; and 3) a novel flame radiation measurement consisting of three band-limited photodiodes, viz.,

200-450nm, 200-1100nm, and 800-1800nm, to capture the shifting wavelength distribution expected during the

transient reduced gravity flame.

2. Experimental observations in microgravity indicate that spherical flames can be obtained during the 2.2 second

test time available in the drop tower, and that these flames evolve through large variations in radiative emissions as

measured by the photodiode detectors. These measured emissions are to be compared to the theoretical model

developed during previous years of this work.

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11-252
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 4/91 EXPIRATION: 3195

BS Students: 0 PROJECT IDENTIFICATION: 9(_2-22-05-29

MS Students: 2 RESPONSIBLE CENTER: LeRC

PhD Students: 0

BIBLIOGRAPHIC CITATIONS FORFY 1994:

Presentations

Atreya. A., Agrawal, S., Sacksteder, K.R.. and Baum. H. "Observations of methane a,ld ethylene diffusion flames

stabilized around a blowing porous sphere under microgravity conditions." AIAA-94-0572. presented at the 32ud AIAA

Aerospace Sciences Meeting, Reno. January 1994.

_|||||_a_|s||_!_H_|_!oa_eo|IonIa!o_|_|_a!_uu_o_o!!_o_!e_|e_!eo_||o_!_I_Is_Ia_Ia|o_nI|I_|_I|IIa|oI|o_IIoI_o|I_|o|_aoI_loo_IIa|Iu_!a|ue_I_I!oIIoI_Io_ao|IooII_a_H_oIaI_oIooIo_IaoR|oIn||_ooo_IoN_oaaoIoooo_oo_ooo_

II-253
Multicomponent Droplet Combustion in Microgravity: Soot Formation, Emulsions, Metal-Based

Additives, and the Effect of Initial Droplet Diameter

PRINCIPALINVESTIGATOR:Pro/'. C. T. Avedisian Cornell University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of the proposed research is to provide insights and data that supports the role of immiscible (e.g.

emulsion) and miscible metal-containing additives, and to examine the influence of the initial droplet diameter on

the combustion of fuel droplets in microgravity. In addition, the feasibility of using a laser-based light scattering

technique for detecting soot formed in spherically symmetric droplet/lames in microgravity, and imaging droplet

flames in microgravity by coupling UV filtering with a conventional CCD camera that is coupled with an image

intensifier, will be examined. Initially the experiments will be performed in a standard aUnosphere.

TASK DESCRIPTION:

The burning of multicomponent droplets is complicated by the influence of composition, which can effect the

formation of soot, lead to multistage combustion in which one component preferentially vaporizes from the droplet

during combustion, or possibly result in the droplet exploding during combustion due to achieving an internal

superheat condition. These problems are extremely complicated, especially that of soot tbrmation. A CCD camera

coupled with an image intensifier for the purpose of recording UV light emissions from the flame droplet will be

measuring the droplet flame diameter and a laser light scattering technique will be set-up to provide a quantitative

measure of soot formation. The experiments will be conducted in a drop tower at Cornell that provides

approximately 1 second of reduced gravity.

TASK SIGNIFICANCE:

Little data have been provided regarding the spherically symmetric burning of unsupported droplets of

multicomponent fuels or emulsions. The importance of examining fuel blends is that most practical fuels which

are burned in combustion-powered devices or incinerators are multicomponent in nature, usually miscible, but

sometimes immiscible (emulsions).

If the mechanism for an influence of initial droplet diameter on spherically symmetric droplet burning can be

understood and predicted for the "simple" spherically symmetric droplet flame, this information may be useful for

providing insights into the influence of initial droplet size on soot tbrmation in a convective environment. Metal

additives can create the potential for significant reductions in particulate emissions by the possible effect of the ions

produced on the nucleation and agglomeration of soot particles, and their possible oxidation; their effect in the

droplet flames, especially in the spherically symmetric configuration, is unknown.

PROGRESSDURING FY 1994:

There is no progress to report at this time since work will not start unul May, 1995.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 5/95 EXPIRATION: 5/99

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-49

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

ill .till|nil Ill n l III Ill Ill Ill OII III Ill lit Ill Ill It I OIllllll l I OI I I It I I I OI l l I l ! I IIll t I I III II I II I II I II I I I OI I IeI I t I I t I I t I It II l I I I I OI OI I II I I I I I I I I I I l I I OII I I I I I I l I OOI I I lI I t I I I It I I I I t I Ii OI I Ill I I i t I It II I I l t I I l I I at I It OI I I I OII II II OOi I I I I I It I I I II I I Il II I I

II-254
Development q{ Advanced Diagnostics .for Characterization qf Burning Droplets in Microgravity

PRINCIPALINVESTIGATOR:Dr. William D. Bach'alo Aerometrics, Inc.

CO-INVESTIGATORS:

Subra V. Sankar Aerometrics, Inc.

TASK OBJECTIVE:

This research is intended to develop rainbow thermometry for quantitative radial temperature measurements in

burning droplets and use Morphologically-Dependent Resonances Lor quantification of the radial regression rate.

Both of these techniques will be developed using devices amenable for use in one of NASA's reduced gravity

aircraft; this hardware will be delivered to LeRC at the end of the project.

TASK DESCRIPTION:

Rainbow thermometry utilizes the angular dependence of rainbow location. In other words, given a known droplet

composition, the location of the rainbow generated by that drop when illuminated with a monochromatic source

will give the refractive index of the drop, and thus. its temperature. Instrumentation and software will be developed

that will permit quantitative droplet temperature measurement.

Morphologically-Dependent Resonances occurs when the droplet diameter is an integral number of wavelengths of

the illumination source. As the droplet size regresses due to combustion, this condition will be repeatedly met,

causing the droplet to periodically "shine." The rate at which this occurs will give the diameter regression rate and

will be accomplished using the same hardware as for the rainbow thermometry.

TASK SIGNIFICANCE:

Droplet combustion is an economically vital phenomenon occurring in liquid-fueled engine combustion, which

includes both mobile and stationary combustors. Optimization of such designs has been hindered due to insufficient

knowledge about the nature of combusting droplets. This project will develop analytic instrumentation that will

allow measurement of the radial temperature distribution and size of combusting droplets. While the tools to be

developed can be used in either normal or reduced gravity, the latter admits the use of much larger droplets and

dramatically increases the intbrmation yield of the experiment.

PROGRESSDURING FY1994:

The contract with Aerometrics was executed on August 1, 1994 and they were so informed on August 18, 1994.

Since the initiation of the contract was late in the fiscal year, Aerometrics has only had time to form a Project Team

and outline a work plan.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 8/94 EXPIRATION: 9/95

PROJECT IDENTIFICATION: 962-22-05-43

RESPONSIBLECENTER: LeRC

I l oI I nI Ill l Ill III l ol l Il Oil II oIll oIll Ul Ill Ill l Ool Ol Ul l el oI oll ol l oI I oI I oooI I I ooI Ol I I l onao| i oi i i l ai I ol iI I Ii l ill ill l ill ill ooolog l I OOOO leo Ill Ill OII l II l Ill Ill |l oII l |ll ! I ooogOlll Ill III l lOO Ill I I l l Ill IOl I Ol OOI l l al i OO Olii l iii ill Oil Oil Oil lOll ill i OOOil i U

II-255
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

Ignition and Combustion of Bulk Metals in Microgravity

PRINCIPALINVESTIGATOR: Prof. Melvyn C. Branch University of Colorado, Boulder

CO-INVESTIGATORS:

Prof. J.W. Daily

G.J. Fiechtner

A. Abbud-Madrid

University of Colorado, Boulder

University of Colorado, Boulder

University of Colorado, Boulder

TASK OBJECTIVE:

This project is an investigation of the mechanisms of ignition and combustion of metals in bulk-pellet forms under

low-pressure atmospheres over a range of gravity levels. The project extends the unique experimental features,

database, and analytical models established in the previous normal-gravity study to the low-gravity environment.

TASK DESCRIPTION:

The preceding NASA-supported project devised an apparatus with a non-disturbing ignition source and dedicated

diagnostics to determine surface and gas temperatures and metal-oxide surface morphology. A database of ignition

delays and combustion behavior was obtained at normal gravity for a number of pure metal specimens. The present

study extends the research to cover metal ignition and combustion behavior in both elevated and low gravity.

Elevated-gravity measurements, already underway in the Geotechnical Centrifuge operated by the University of

Colorado, are to be completed. The observation of the metal surface during ignition and combustion is possible

through high-speed cinematography, using a camera on loan from the Lewis Research Center. Metal-oxide

combustion specimens are recovered after each test and analyzed physically and chemically by electron microscopy.

The compact, remotely operated apparatus used on the centrifuge will then be modified to meet the requirements and

limitations tor low-gravity experiments, to be conducted by the investigators in the Lewis Research Center airplane

facility.

The analytical study involves numerical modeling of the metal heating, ignition, and combustion processes as

influenced by gravity level and oxygen pressure. The initial findings were verified by the normal-gravity

measurements of metal temperature rise, with excellent agreement. Extended modeling will incorporate the

variations in heat loss by natural convection, to be validated by the elevated- and low-gravity measurements. The

experimental results will also contribute informauon essential lor the addition of surface and gas-phase reaction

processes into the modeling.

TASK SIGNIFICANCE:

This study offers a novel means of observing and interpreting metal combustion using a radiant-energy ignition

source and a simplified convection-controlled environment. The results offer new scientific information on metal

combustion reactions, and they promise practical applications to the management and safety of spacecralt cryogenic

propellant systems.

PROGRESSDURINGFY 1994:

The quantitative measurement capabilities of the normal-gravity experimental study were extended to supplement the

temperature measurements and visual observations obtained in the preceding year. Pure-metal spectmens slightly

smaller than before, 4 Inm in diameter and 4 mm high, were heated by the unique radiant source of a 1000-W Xe

short-arc lamp. The added diagnostics included a spectrograph-array detector system, scanning electron microscope

(SEM) metallography, and X-ray spectrometry of specimens quenched at various stages during heat-up and

combustion. In addition, surface-temperature histories indicative of the distinct stages of heat-up, ignition, and

combustion were obtained over an elevated acceleration range of 2 to 20 g (g=9.8 m/s :) in the University of

Colorado Geotechnical Centrifuge.

_n_tqD_n_Dts_een_jo_DDn_1n_o_n_n_ou_un_ut_n_n_n_e_t_n_g_nu_n_e_t_e_I_nn_e_et_n_oo_u_6m__mo_*_u;_n_O_eni_u_e_Q_u_D_D_D

11-256
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

. "_IH_i_|i11_1i_|_!_1i_*_"_"_"_IiH_"Hij_i_H_i_ m l.l.,i, iiil,.i.,lll,.,i.,|¢tllll|!llHl¢lm.,,.la, ell,* N lll,llHllllll,m.,.i.iol.l.,.lll,,.,.a.l.,.i.i.

The baseline screening tesLs were conducted with 8 different pure metals selected to exhibit a range of ignition and

combustion behavior. The additiontd measurements were each conducted with a single metal for simplil]cation,

however.

The time-resolved measurement.s of gas-phase emission spectra in the reaction field were conducted with magnesium

(Mg) specimens. A spectrograph with a diode-array detector gave a refined measurement of color temperature from

the broad-band continuum spectrum. Prominent lines in the narrow-band spectra established the abundance of Mg

and its MgO product through identified electronic and vibration resonances. This information will be very useful in

determining the effect of gravity-induced convection in gas-phase reactions of bulk metals.

The SEM surface-morphology and chemical analyses of quenched specimens were conducted with copper (Cu)

specimens. The oxidation sequence of Cu at various stages of the heating and combustion processes was determmed

from the identification and location of surface reactants and products, with further corroboration by quantitative

electron microprobe analysis. It is anticipated that in microgravity the chemical nature of the oxide layer will be

'altered by the lack of convective transport of oxygen adjacent to the metal surface.

The elevated-gravity measurements were conducted with titanium (Ti) specimens. The complete experimental

system was mounted on swiveling baskets at both ends of the rotating arms of the centrifuge. Power, control, and

data signals were transmitted through slip rings. An additional silicon photodiode was installed to monitor any

changes in the Xe arc lamp output due to the increased acceleration environment. Results of the testing, in terms of

the time-related temperature responses, indicate a distinct change in the heating rate of the Ti samples. At 3 and 5g,

the heating rate decreases and the ignition delay increases, although the ignition temperature remains comparable to

that at normal gravity. At higher accelerations, however, the trend reverses and ignition delay decreases. In fact, at

15 and 20g, the heating rate is greater that at normal gravity and the ignition temperature appears to be higher. This

behavior is apparently due to the competing effects of the increase in the transport rate of oxygen to the metal

surface and the increase in cotwective heat loss with acceleration. This plausible mechanism will be confirmed in

further experiments with a variety of metals and oxidizing atmospheres, along with more detailed spectroscopic

diagnostics.

This project is to conclude early in FY 1995 (November 1994). Design activities are initiating to modify the

apparatus for installation in an airplane facility, for a follow-on microgravity project already approved for support by

NASA Headquarters.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

Phi3 Students: 2

TASK INITIATION: 4/91 EXPIRATION: II/94

PROJECT IDENTIFICATION:962-22-05-30

NASA CONTRACT NO.:NAG3-1257

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Abbud-Madr_, A., Fiechtner, G.J., Branch, M.C.,and Daily, J.W. "A study of bu_ metalignitionin oxygen

atmospheres." The Combustion Institute, Fall Meeting oftheWestern S_tes Section, WgS/CI 93-079, October 18-19,

1993.

Presentations

Abbud-Madrid, A., Fiechtner. G.J., Branch, M.C.. and Daily, J.W. "Ignition and combustion characteristics of pure bulk

metals: Normal gravity test resulL_." AIAA Paper 94-0574. 32nd Aerospace Sciences Meeting and Exhibit, Reno. NV.

January 10-13, 1994.
Ignition and Combustion of Bulk Metals in Microgravity (Ground-Based Experiment)

PRINCIPALINVESTIGATOR:Prof. Melvyn C. Branch University of Colorado, Boulder

CO-INVESTIGATORS:

Prof. J.W. Daily

A. Abbud-Madrid

University of Colorado, Boulder

University of Colorado, Boulder

TASK OBJECTIVE:

This project is an investigation of the mechanisms of ignition and combustion of metals in bulk pellet forms under

low-pressure atmospheres over a range of gravity levels. The project extends the unique experimental features,

database, and analytical models established in the previous normal gravity study to the low gravity environment.

TASK DESCRIPTION:

The preceding NASA supported project devised an apparatus with a non-disturbing ignition source and dedicated

diagnostics to determine surface and gas temperatures and metal oxide surface morphology. A database of ignition

delays and combustion behavior was obtained at normal gravity for a number of pure metal specimens. The present

study extends the research to cover metal ignition and combustion behavior in both elevated and low gravity.

Elevated gravity measurements, already underway in the Geotechnical Centrifuge operated by the University of

Colorado, are to be completed. The observation of the metal surface during ignition and combustion is possible

through high-speed cinematography, using a camera on loan from the Lewis Research Center. Metal oxide

combustion specimens are recovered after each test and analyzed physically and chemically by electron microscopy.

The compact, remotely operated apparatus used on the centrifuge will then be modified to meet the requirements and

limitations for low gravity experiments, to be conducted by the investigators in the Lewis Research Center airplane

facility.

The analytical study involves numerical modeling of the metal heating, ignition, and combustion processes as

influenced by gravity level and oxygen pressure. The initial findings were verified by the normal gravity

measurements of metal temperature rise, with excellent agreement. Extended modeling will incorporate the

variations in heat loss by natural convection, to be validated by the elevated and low gravity measurements. The

experimental results will also contribute information essential for the addition of surface and gas-phase reaction

processes into the modeling.

TASK SIGNIFICANCE:

This study offers a novel means of observing and interpreting metal combustion using a radiant-energy ignition

source and a simplified convection controlled environment. The results offer new scientific information on metal

combustion reactions, and they promise practical applications to the management and safety of spacecraft cryogenic

propellant systems.

PROGRESSDURING FY 1994:

This project is not scheduled for initiation until December 1994, upon completion of the current normal and

elevated gravity project.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/94 EXPIRATION: 11/97

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-30

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 2

t I t I I IIt t I itl it i t I I I I tlit I I t I ii i iliii i i I t II IIIII I i i I t l i i* I Ii i I I t t I i i i I i i t t tt t i t t It t I t I I III i i t I t t t i i It I It t I liilllll III Ill I t l I It I II II I I t l I III I t t it I I i II III t I I t II III t l I II I II I III I I t I I I It I I II I IIf t tl I I I tll tll t II t t I III III i| t t I I t II tl It I I II I llI tl I I t I I lit

11-258
Modeling of Microgravity Combustion Experiments

PRINCIPALINVESTIGATOR:Prof. John D. Buckmaster University of Illinois, Urbana-Champaign

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

Modeling of existing microgravity expertments for amproving our understanding of the fundamental physics, with

particular emphasis on (a) premixed gaseous combustion processes, particularly those involving purely diffusive and

very slow convective velocities= and (b) chattering flame propagation in premixed particle cloud combustion.

TASK DESCRIPTION:

Microgravity combustion experiments amenable to modeling are identified, and analytical and numerical models are

developed from first principles for various systems and configurations. Model predictions are compared with

experimental results and necessary adjustments and enhancements are incorporated into the models. Precise

quantitative comparisons are made with numerical results where possible.

TASK SIGNIFICANCE:

Modeling provides invaluable physical insights into the experimentally observed behavior. This study is done in

close collaboration with experimentalists with the goal of providing a clear understanding of the underlying physics.

PROGRESSDURING FY 1994:

A presentation entitled "Unsteady Spherical Flames Generated by Point Ignition of Combustible Mixtures

Containing Inert Particles," by J. Buckmaster and A. Agarwal was given by J. Buckmaster at the 5th Int. Conf. on

Numerical Combustion in Garmisch, Sept. 27 - Oct. 1, 1993.

A poster session presentation entitled "Unsteady Spherical Flames in Dusty Gases," by J. Buckmaster mid A.

Agarwal was given at the 25th International Symposium on Combustion, Irvine, CA, 1994. It is also submitted to

a journal as a paper li}r publication. The abstract of the paper reads: "We examine an expanding spherical premixed

llame propagating in a mixture containing inert dust. The presence of the dust generates a significant radiative

energy flux that influences the flame speed. With the adoption of a hydrodynanuc description in which stretch

effects are accounted for using an empirical formula, and with the use of the Eddington approximation to describe

the radiation, a simple numerical problem is formulated valid for that initial time interval in which the flame

temperature changes by O(e) amounts where E is the sm'a.ll inverse activation energy. Solutions are constructed

using parameter values appropriate to lean CH4/air mixtures, and for modest particle loadings. We describe the

competition between the Zeldovich-Spalding effect in which radiative losses on the diffusive scale tend to quench the

flame, and the Joulin effect in which radiative preheating on the scale of the Planck length tends to strengthen the

flame."

The paper entitled "The role of slip in the generation of acoustic instabilities in gas turbine combustion systems,"

by M. DiCicco and J. Buc_naster was completed in December 1993 and submitted for publication. The abstract of

the paper reads: "In the context of gas turbine combustion chambers, this study describes how slip affects the

response time of fuel sprays to pressure fluctuations in a gaseous flow field. Slip between the condensed and gas

phases is shown to cause fuel vapor mass traction fluctuations upstream of the reaction zone. A resulting

oscillating heat release can drive the pressure fluctuations, depending on the phase difference between them. This

generates an acoustic instability. With relevance to previous experimental results, differences are explored in the

evaporation characteristics among three different fuel sprays (JP-4, JP-5, and D-2) in relation to their effect on the

magnitude of the fuel vapor mass traction perturbations. Parameters such as droplet sizes, inlet air temperatures, air

velocities, and initial Reynolds numbers, are varied with their corresponding influence examined."

I1-259
II. MSADProgramTasksw Ground-based Research Discipline: Combustion Science

The paper entitled "Acoustic instabilities driven by slip between a condensed phase and the gas phase in combustion

systems," by M. DiCicco and J. Buckmaster was presented by M.DiCicco (graduate student) at the 32nd AIAA

Aerospace Sciences Meeting, Reno, Nevada, in January 1994. The abstract of the paper reads: "In the context of

gas turbine combustion chambers, this study describes how slip affects the response time oi fuel sprays to pressure

fluctuations in a gaseous flow field. Slip between the condensed and gas phases is shown to cause the fuel vapor

mass traction fluctuattons upstream of the reaction zone. A resulting oscillating heat release can drive the pressure

fluctuations, depending on the phase difference between them. This generates an acoustic instability. With

relevance to previous experimental results, differences are explored in the evaporation characteristics among three

different fuel sprays (JP-4, JP-5, and D-2) in relation to their effect on the magnitude of the fuel vapor mass traction

perturbations."

The paper entitled "Intrinsic and acoustic instabilities in flames fueled by multiphase mixtures," by C.J. Lee, J.

Buckmaster, and M. DiCicco was published in Combustion Science and Technology in 1994. The abstract of the

paper reads: "We describe linear stability results for flames fueled by mixtures of air and particles. Nonsimilarity

between the temperature and fuel concentration fields gives rise to an intrinsic pulsating instability for unconfined

flames (a single mode). Acoustic interactions for confined propagating flames generate acoustic instabilities (an

infinite number of modes) when the gas-phase velocity is different from that of the solid phase (i.e. there is slip).

The confinement modes can not, in general, be classified as intrinsic, fundamental, l_'st-harmonic, etc. For

example, for propagation in a tube with flame initiation at the open end, a mode can start as the second harmonic

but finish, when the flame is at the closed end, as the fundamental. Instabilities tend to be suppressed in spherical

flames generated by point ignition in a confinement vessel. The triggering of acoustic instabilities in gas turbines

by slip between fuel drops and air is discussed, and we show that the role of slip is quite different when the

condensed phase is injected at a finite point rather than being dispersed throughout the gas phase."

The paper entitled "The effects of radiation on the thermal-diffusive stability boundaries of premixed flames," by J.

Buckmaster and T. Jackson was accepted for publication in April 1994 in Combustion Science and Technology.

The abstract of the paper reads: "We examine the stability of premixed flames in mixtures containing significant

amounts of fine dust whose sole impact is upon the radiative transport. By using well-established modeling

strategies together with a simple radiation model which preserves much of the essential physics, it is possible to

explore to what extent radiative transport displaces the classical non-hydrodynamical stability boundaries of the

plane deflagration. Analysis is possible for arbitrary values of both the Planck length and the Boltzman number. It

is shown that the pulsating/traveling- wave instability is strongly enhanced by the presence of radiation, and can be

present even if Le<l. On the other hand, radiation tends to suppress the cellular instability normally associated

with values of Le less than 1. The latter is consistent with preliminary experimental observations of Abbud-Madrid

and Ronney."

The paper entitled "Absolute flammability limits and flame-balls," by D. Lozinski and J. Buckmaster was published

in Combustion and Flame in 1994. The abstract of the paper reads: "We examine flame balls that are not optically

thin so that radiation from the hot burned gas is not lost but is reabsorbed by the surrounding cool gas. The steady

solution is shown to be multivalued in general and defines an intrinsic (apparatus independent) flammability limit

for a sufficiently small ignition source. Beyond the flammability limit a steady solution exists for arbitrarily weak

mixtures, but is unrealizable since it is unstable to one-dimensional perturbations. An unsteady propagating flame

solution is also possible for arbitrarily weak mixtures, but can only be generated by a large ignition source.

Observations of flame- strings in SF6-diluted mixtures are reported and suggest that the peculiar nature of the

radiative properties of SF6 is responsible for peculiar dynamics."

The paper entitled "Quenching of opposed forced flow smoulder," by D. Lozinski and J. Buckmaster was presented

by D. Lozinski, post-doctoral associate, at the Spring Meeting of the Canadian Section of the Combustion Institute

in May 1994. This work was subsequently completed as a paper entitled "Quenching of flames in reverse

smoulder," by D. Lozinski and J. Buckmaster in June 1994 and submitted for publication. The abstract of the paper

reads: "A simple model of reverse smoulder in a porous medium is analyzed using asymptotic methods. When the

only chemical reaction is exothermic oxidation, the burning rate is a single-valued function of the blowing rate,

increasing from zero to a maximum, and then returning to zero. When endothermic pyrolysis is added to the

description, the burning rate is double-valued for blowing rates less than some maximum. Beyond this maximum

11-260
there are no solutions. Tile upper branch oi the double-valued solution is the physically relewmt one. Ou it, for

certmn choices of parameters, the burning rate increases from zero to a maximum, and then decreases until

quenching occurs at the maximpm blowing rate. This behavior mimics experimental observations by Torero,

Femandcz-Pello, and Kitano ( 1993)."

Tile paper entitled "The role of mathematical modeling in combustion," by J. Buckmaster was published in a book

entitled Combustion in High Speed Flows, J. Buckmaster. T. Jackson, and A. Kumar, eds., Kluwcr Academic

Publishers, The Netherlands, 1994, pp. 447-459. (S. Gokoglu)

The book entitled Combustion in High Speed Flows was published, J. Buckmaster, T. Jackson, and A. Kumar

editors, by Kluwer Academic Publishers, The Netherlands, in 1994.

The paper entitled "Some topics in reverse smoulder," by J. Buckma_ster and D. Lozinski, based on a presentation

made by J. Buckmaster at a US/Japanese Workshop on Modeling in Combustion, held in Kauai, July 1994, was

completed and submitted m August 1994 for the Workshop Proceedings. The abstract of the paper reads: "The role

of thermal uon-equilibntnn and endothcrmic pyrolysis is discussed in the context of a simple model of reverse

smoulder combustion. It is shown that non-equilibrium has little qualitative effect on the nature of the solutions.

but endothermic pyrolysis can lead to quenching at sufficiently large blowing rates."

The paper entitled "An elementary discussion of forward smoldering," by J. Buckmaster, C. Fernandez-Pello, and D.

Loziuski is submitted for publication. The abstract of the paper reads: "We describe an elementary model of

_)ne-dimensional unsteady forward smoldering, purged of 'all unnecessary, physics. Following work of Dosanih and

Pagni, a late time solution is constructed, characterized by two reaction fronts - an exothennic oxidation front, an

unusu',d kind of diffusion flame; and an endothermic pyrolysis front. It is shown that the flame temperature and the

ratio of the speeds of the two fronLs relative to the solid are independent of the blowing rate, in agreement with data

obtained by Ohlemiller and Lucca. The structure of the oxidation front is described in the context of 1-step

Arrhenius kinetics, and it is shown that leakage of solid reactant through the front is possible, but not ie',A:age of

oxygen. An elementary pyrolysis structure is "also examined which reduces to the frontal model in a certain limit,

and clarifies il,s nature."

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 2/91 EXPIRATION: 12/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-22-05-31

MS Students: 3 MS Degrees: 2 RESPONSIBLE CENTER: LeRC

PhD Students: 0 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Buckmaster, J. The structure and stability of laminar flames. Annu. Rev. Fluid Mech. vol. 25, 21-53 (1993).

Buckmaster. J. The role of mathematical modeling in combustion. Combustion in High Speed Flows, Kluwer Academic

Publishers. The Netherlands. 447-459 (1994).

Buckmaster. J. and G, Joulin Comb. Sci. & Tech., vol. 89, 57-69 (1993).

Buckmaster. J. and Jackson. T. The effects of radiation on the thermal-diffusive stability boundaries of premixed flames.

accepted by Combustion Science and Technology, (1994).

Buckmaster, J. and Lozinski. D. Some topics in reverse smoulder, to appear in the Proc. of US/Japanese Workshc_p on

Modeling in Combustion . in Kauai, (August 1994).

DiCicco. M. and Buckmaster, J. Accountic instabilities driven by slip between a condensed phase and the gas phase in

combustion systems. AIAA. 94-0103. (1994).

i i i iii iI i iI i i i i ii i i i I II I I I i I i i ii i i ii i ii i i i i i i I Ii i i i ii I i i i i I I I i i i I i i i iI ii I I i i i I i i II i i i I i i i I I i i ii i i i i n i II I i I I i i ii I ii iii I i I I ii I I Ill i ii i I I i i i i i i Ii iI i ii i iI I i i I i i i i I i I ii i I i i ii i i i i I I I i i ii i I I I i I i i i i i Iiii i I i i i i i i i iiiii i i i i i i i I i Iii i i i i i i iii i i i i i i ii ii i i i i i

I1-261
[l. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

Lee. C.J.. Buckmaster. J. and DiCicco. M. Intrinsic and acoustic instabilities in flames fueled by multiphase mixtures.

C_mb. Sci. & Tech. vol. 98, 161 (1994).

lx_zinski. D. and Buckmaster. J. Absolute flammability limits and flame-balls, Comb. & Flame. w_l. 97. 301-316 (1994).

Presentations

Buckmaster, J. and A. Agarwal "Unsteady spherical flames generated by point ignition of combustible mixtures

c_mtaining inert particles." presented at the 5th Int. Conf. on Numerical Combustion in Garmisch, September 27 - October

l, 1993.

Buckanaster. J. and A. Agarwal ....Unsteady spherical flames in dusty gases"." presented at the 25th Int. Syrup. on

Combustion, The Combustion Institute. Irvine. CA. July 31 - August 5. 1994.

Buckmaster, J. and Agarwal. A. "Unsteady spherical flames in dusty gases." poster session presentation at the 25th Int.

Syrup. on Combustion, Irvine, CA, July 31 - August 4, 1994.

Buckmaster. J. and DiCicco. M. "Acoustic instabilities driven by slip between a condensed phase and the gas phase in

combustion systems." presented at the AIAA 32nd Aerospace Sciences Meeting, Reno. NV. Jan. 10-13. 1994.

Buckmaster, J. and Jackson. T. "The effect of radiative transport on the thermal-diffusive stability boundaries of premixed

flames." poster session presentation at the 25th Int. Syrup. on Combustion. Irvine. CA, July 31 - August 4. 1994.

Buckmaster. J. and Lozinski, D. "Some topics in revedrse smoulder." presented at the US/Japanese Workshop on

Modeling in Combustion, Kauai, July. 1994.

Lozinski, D. and Buckmaster, J. "Quenching of opposed forced flow smoulder." presented at the 1994 Spring Technical

Meeting of the Canadian Section of the Combustion Institute, 10-13 May, 1994.

Lozinski, D. and J. Buckmaster "Quenching of opposed forced flow smoldering combustion." presented at the 1994

Spring Technical Meeting of the Canadian Section of the Combustion Institute, May 10-13, 1994,

II-262
Buoyancy Effects on the Structure and Stability of Burke-Schumann Diffusion Flames

PRINCIPALINVESTIGATOR: Prof. L. D. Chen University of Iowa

Co-INVESTIGATORS:

Dennis P. Stocker NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The general goals of the proposed research are to improve our understanding of (1) the influence of buoyancy on

co-flow diffusion flames, e.g., Burke-Schumann diffusion flames, and (2) the effects of buoyancy on vortex-flame

interactions in co-flow diffusion flames. The overall objectives of the proposed work are to:

1. Verify the zero-gravity Burke-Schumann model and the gravity-dependent Hegde-Bahadori extension.

2. Investigate the flame stability in a buoyancy-dependent flow-field as affected by the co-flow oxidizer.

3. Examine the state relationships of co-flow diffusion flames.

4. Study flow vortex and diffusion flame interactions.

TASK DESCRIPTION:

In order to meet the objectives, the phenomena will be investigated by:

1. Microgravity testing.

2. Normal-gravity testing (e.g., at reduced pressure to emulate reduced gravity).

3. Numerical modeling.

D. Stocker (NASA LeRC) will have the lead responsibility for the microgravity testing, which will be generally

conducted in the 2.2-second Drop Tower. The tests will be conducted in the rig fabricated for Stocker's precursor

studies of Burke-Schumann diffusion flames. Also, D. Stocker and L.-D. Chen will consider testing in the Zero-G

Facility and in research aircraft (e.g., DC-9) if a need is identified. In either case, the tests will most likely be

conducted in rig(s) built for the Gas-jet Diffusion Flame (GDF) Experiment, since only limited modification would

be required.

Normal-gravity tests will be conducted under the direction of Prof. Chen at the University of Iowa and possibly at

the Wright Laboratory (at WPAFB, in Dayton, OH), since the WPAFB facilities have been made available to this

project at no cost. The normal-gravity experiments will complement the microgravity experiments, but will

include tests that cannot be readily conducted in the rmcrogravity facilities. For example, some instrumentation

(e.g., NOx analyzer) that will be used in the normal-gravity testing cannot readily be used in the microgravity tests

due to various constraints (e.g., time required for measurement, size of instrument, "ruggedness" of instrument,

etc.).

Prof. Chen will direct the numerical modeling which will be conducted at the University of Iowa. An existing,

semi-implicit, transient, axisymmetric code will be modified to include gas-phase radiation, state relationships or

reduced mechanisms for major species, and finite chemistry for NOx. The predictions will be verified by the

experimental measurements.

TASK SIGNIFICANCE:

The 1928 Burke-Schumann diffusion flame analysis is of fundamental and historical interest, and can be found in

many, if not all, introductory combustion textbooks in the U.S. Experimental validation of this zero-gravity model

will be an important contribution to combustion science, and it is likely to be referenced in future textbooks.

Additionally, the study results could lead in the long-term to improved engine or furnace efficiency and reduced

pollutant emissions.
PROGRESSDURINGFY 1994:

During FY94, the work was focused on the development for upcoming tests and the modeling and analysis of

previous results. There were no microgravity tests conducted in FY94, due to the shut down of the 2.2-second

Drop Tower. The analysis of the pulsed Burke-Schumann flame tests conducted in FY93 was presented at the

WSS/CI Fall 1993 meeting and in a poster session at the Twenty-fifth International Symposium on Combustion,

in August 1994.

Hardware Development

Whereas the previous microgravity tests have been limited to photographic studies of the flame structure, the

upcoming tests (to begin in FY95) will include measurements of temperature, species, etc. For this reason, a

significant effort was focused on the hardware preparation for the upcoming microgravity tests.

In the tall of 1993, D. Stocker was assisted in this effort by two undergraduate interns receiving design course credit

from Worcester Polytechnic Institute. Flow visualization in the co-flow of the Burke-Schumann burner was

demonstrated using streak imaging, by seeding the air flow with phenolic microballoons or smoke (from

model-train smoke fluid). Shadowgraph imaging (using an expanded beam from a 15-mW HeNe laser) was used to

visualize the hot plume above the flame. Additionally, tests were conducted with various slot burners in preparation

for the design of slot burner(s) to be included in upcoming tests. Slot flames are of interest, since the analysis of

Roper and Hegde & Bahadori predicts that they will be more strongly dependent on buoyancy than the axisymmetric

flames studied by Stocker thus far.

J. Goldmeer, a LeRC GSRP fellow, and D. Stocker conducted preliminary normal-gravity tests using thin filament

pyrometry (TFP) to measure temperature profiles across a flame. Multiple fibers were imaged with a standard video

camera, via an interference filter, providing a strong intensity and low noise with the camera at maxtmum gain.

Intensity profiles along each fiber are easily obtained using the Image Processing workstation. Calibration of the

video intensity vs. flame temperature will be done in F-"Y95. TFP will be the primary method for temperature

measurement in the upcoming drop tests.

LeRC provided a driver for a proportional control valve to produce sinusoidal variations in the fuel flow tor pulsed

flame studies. The droppable device sinusoidally varies the flow, and provides (nearly) independent control of the

frequency and amplitude (both dc and ac) of the flow. Although there may be some hysteresis in the flow, the

preliminary tests are promising. The periodic flow ti'om the device will be characterized in FY95.

Work is in progress on the definition of requirements and the conceptual design of circular and slot

Burke-Schumann burners, which will be appropriate for smoke-fluid flow visualization, thin-filament pyrometry,

absorption spectroscopy for species measurements, and traditional instrumentation (e.g., thermocouples). For the

species measurements, a new source/detector array will be designed, that will mate with the burner chimney and be

used with the spectroscopy system developed by Southwest Sciences, Inc. The burners will include interchangeable

chimney segments appropriate to the different measurement techniques.

Modeling & Analysis

Stocker and the two WPI interns coded a computer program for predictions of the height and shape of slot flames for

three conditions: (1) no gravity and no axial diffusion, (2) with gravity but no axial diffusion, and (3) no gravity but

with axial diffusion, based on the works of (1) Burke & Schumann, (2) Chung & Law, as well as Roper, and (3)

Hegde & Bahadori.

Modeling was also performed at the University of Iowa for comparison with the pulsed flame tests conducted by

Stocker in FY93. A correlation was established between the tip cutting and the appearance of flow vortices. The

numerical modeling showed that the tip cutting coincided with vortex formation near the tip of the flame in lg, and

near the base of the flame in 0g. Furthermore, animation of the vorticity field has shown that the baroclinic effect

in the fuel-lean region acts as a source term in vortex dynamics, while thermal expansion is a sink term.

i I ii I i I I II I i11 I I I I I LlII QI II I |111 II I I I II I I II I I I I I I I II I II I I I I I I I IQII I II I II I I | III I II I I QI II II II III III II QIII I I II I I I II I II III I I III I I I III IIII I Ii II I III IIIi i lllll III Iii n i iii I QI II I II I II I I II I I I I I I III I llll I I I I II II III I I I I I I It I It QI II I IIIll I II I II I II I n I I11 Ii I

11-264
II.MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

The modeling was unable to predict, however, observed subharmonic flame response, which presumably results

from vortex merging. This held true despite the use of FCT correction lbr convective transport, various velocity

profiles, and various wavelbrrns in the modeling. Based on these results, differential pressure measurements were

made of the flow pulsation system, but they revealed a fundamental response, ruling out the solenoid valve as the

cause of the subharmonic response observed in the flames.

Nonetheless, numerical simulation of a flame pulsed at 1 Hz has shown the effect of buoyancy on the flame's

spectral response. The norm'd-gravity flame spectrum appears to consist of linear combinations of two dominant

frequencies, 1 and 4 Hz. The microgravity flame spectrum showed only one dominant frequency, the 1-Hz forcing

frequency.

Modeling and normal-gravity experiments at University Iowa revealed a harmonic response (in flame height and

temperature traces) in Burke-Schumann flames pulsed at 1 to 4 Hz. Thus results thus far show that buoyancy is an

important parameter in this nonlinear flame response (as suggested by Stocker's drop tests). A paper is being

prepared describing the numerical "algorithm, that will use this finding as an example of tile importance of using a

high-order scheme (spatial) for accurately predicting flame dynamics.

STUDENTSFUNDEDUNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/98

BS Students: 0 PROJECT iDENTIFICATION: 962-22-05-63

MS Students: 1 RESPONSIBLECENTER: LcRC

PhD Students: 2

I1-265
It. MSADProgramTasks-- Ground-based Research Discipline: Combus_on Science

H I|In_oo_|o_u_om_u_oi_H_o|_8|_|_on_|_oI_u_o_u_o_i_no_io_a_|_|nn_n_|_||_|_|_|_Hn_H_o_|H_|_1_aanl_H_"_11_"n_nIon|1I_on_1_no1n1I_"_;_n|a_onn_Hno1|1_nHn_n_H I on|ollol.llnlllll_lnH|lntlnollOlllll$11olnol!

Gravitational Effects on Premixed Turbulent Flames

PRINCIPALINVESTIGATOR:Dr. Robert K. Cheng Lawrence Berkeley Laboratory.

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The overall objectives of this experiment is to investigate experimentally the dynamics of low Reynolds number

prenuxed turbulent flames in a microgravity environment.

TASK DESCRIPTION:

The emphasis of this experimental program will be on measuring flame wrinkle scales and imaging mean flowfield

properties of conical Bunsen-type flames and rod-stabilized v-flames. Laser diagnostics will be used to obtain

statistical scalar and velocity information to evaluate parameters suitable for predicting the effects of gravity on

turbulent premixed flames. A 2.2 second drop tower, and Leafier parabolas will be performed as well as parallel

laboratory experiments.

TASK SIGNIFICANCE:

This research effort will provide insight to determine significant processes through which gravity affects flame

properties such as flame speed and flame structures. The results will be used to determine the gravity-influenced

limit for premixed turbulent flames. Such knowledge is valuable for guiding the development of turbulent

combustion models to include the effects of gravity. This experimental study will contribute to resolving the

inconsistencies that exist between experiments and theories and help couple chemical and fluid mechanical processes

found in many turbulent combustion environments. If better understood, turbulent combustion can be exploited to

enhance burning rates and volumetric power density in many heating and power generating systems.

PROGRESSDURINGFY 1994:

An experimental rig that had been used in the 2.2-second Drop Tower was converted for the Lear jet. The behavior

of laminar and turbulent Bunsen type conical and rod stabilized v-flames has been observed by the use of laser

schlieren. The tests are follow-on experiments based on 2.2 second drop tower work from previous years. The

schileren images are recorded on videotape and are analyzed by computer-controlled image processing. Comparison

of the microgravity results with those under normal gravity shows the gravity affects flame propagation through the

coupling of the flame dynamics and the surrounding flowfield. Under normal gravity, buoyancy-driven flow

instabilities are shown to induce flame flickering.

The emphasis of the microgravity experiment was on measuring mean flame properties and compared them with

those observed in the laboratory under normal gravity and reversed gravity. In addition to the use of laser schilerenl

the laboratory flames are also interrogated by other laser technique to measure their scalar and velocity statistics.

These information are needed to evaluate parameters suitable for predicting the effects of gravity on premixed flames.

The data will be useful for comparisons to theoretical models which do not include the effects of gravity. The study

will assist in understanding the relationships between turbulence and low-gravity combustion.

The analysis of the schileren video during the Learjet experiments has begun. For the laminar flame cases, the

median of the intensity is extracted to represent the mean flame position. For the turbulent flame cases, the task was

more difficult due to the broad flame position. Different methods are being explored to obtain consistent and

reproducible representation of the turbulent flames. The analysis of gravity-driven pulsating frequency of the

Bunsen flame is complete. An emperical correlation is found for all the pulsating frequencies measured in our

laboratories and those reported previously by others. The independent parameter is the square of Strouhol number

over the Richardson number. The dependent parameter is the Reynolds number to the power of 2/3. The influence

of gravity on the stabilization limits of Bunsen flames and rod-stabilized v-flames are also determined. These results

_Ion_o_D_n_=_I_o_i_oo_o_I_o_o_g_*_qo_qoI_oo_*_o_o$o_*_o_oD_uo_oo_*_*_o_o_o_o_*D_o_ononono_o_*b_*_*b_oD_o_o_iu_u_uo_oou_n_u_oo_o_l_1e_*_u_u_t_o_

I1-266
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

.nl|lulo|loollellollg|nlllll|ll|llolllulllul|llnlnnllllllllliH HllnlHlIHlllllllJlnllHl.llllll0i01i|lillIHlllll|l|lllllllllHillnltll J llllllllHIH01Hl|nllll|Jnll|lU H I01111HillllllnHlllllllllll J|HIIl_nlH H_lHIl.l_ll_ln|_l|l H_

are useful for designing future microgravity experiment and to elucidate the processes important to characterizing the

coupling between gravity and premixed flames.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/91 EXPIRATION: 3/95

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-32

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 1

ii I I I I I I ii I ii i i i i i l i i I l i I I II II i I I i I II i ii i i l l i I I i i i i i l i I I i i I I I I I I i i i ii I II I IIi i ii iii i ii I I I III II I I i I II I III I ill IIi I i I III III I III I i l III III I II I i lliiii I i I I I I I iI l i I I i I I i I I II II I I I I I I i I I II i I i I I II II iiii I I i I i I I I I II I II I I I I I I I I I I I I I I II I I I I I I I I I I II I II ! I I I I I ! I I

11-267
Gravitational Effects on Premixed Turbulent Flames: Microgravity Flame Structures

PRINCIPALINVESTIGATOR: Dr. Robert K. Cheng Lawrence Berkeley Laboratory.

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The overall objectives of this experiment is to investigate the influence of gravity on premixed turbulent flame

propagation.

TASK DESCRIPTION:

The emphasis of this experimental program will be on measuring flame wrinkle scales and imaging mean flowfield

properties of conical Bunsen-type flames and rod-stabilized V-flames. Laser diagnostics will be used to obtain

statistical scalar and velocity information to evaluate parameters suitable for predicting the effects of gravity on

turbulent premixed flames. Learjet parabolic flights will be performed as well as parallel laboratory expertments.

TASK SIGNIFICANCE:

This research effort will provide insight to determine significant processes through which gravity effects/'lame

properties such as flame speed and flame structures. The results will be used to determine the gravity-influenced

limit for premixed turbulent flames. Such knowledge is valuable for guiding the development of turbulent

combustion models to include the effects of gravity. This experimental study will contribute to resolving the

inconsistencies that exist between experiments and theories and help couple chemical and fluid mechanical processes

found in many turbulent combustion environments. If better understood, turbulent combustion can be exploited to

enhance burning rates and volumetric power density in many heating and power generating systems.

PROGRESSDURING FY 1994:

There is no progress to report at this time since work will not begin until March, 1995.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 3/95 EXPIRATION: 3/97

PROJECT IDENTIFICATION: 962-22-00

RESPONSIBLECENTER: LeRC

i i I I _i i | iii i i ! I i i i | | i i I i o! ! I !i I | ei i ! i I t eit i I i i I ! i ! I I o! I i i es ! i i I i !i i ii eI ! i i ! | ! iI !I i i I I i i ! Iii ! !| I I i I I | I I i! ! I ! I ! I I I | I i i I set eelee |111111111 | I! I i ! | i I i eI ! ei ! i i i ii i i i i i I I! | Ie |I e| ei i I I I! e !! ei i i ! ! i ! oi oo| | i i i i i i 111 ti i it i i ! ei i i ! !i i i i i i i i ! i ! ioI i i ! i * i i i i I ii

11-268
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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Combustion of Interactin_ Droplet Arrays in a Micro_ravity Environment

PRINCIPALINVESTIGATOR: Dr. Daniel L. Dietrich NYMA, Inc.

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

This research program involves the study of one-dimensional and two-dimensional arrays of droplets in a

buoyant-fi'ee environment. The purpose of the work is to extend the data base and theories that exist for single

droplets into the regime wherein droplet interactions are important.

TASK DESCRIPTION:

The emphasis of the present investigation is experimental, although comparison will be made to existing

theoretical and numerical treatments when appropriate. Both normal-gravity and low-gravity testing will be

employed, and the results compared.

The normal-gravity testing will utilize the classical suspended droplet technique; single droplets and droplet arrays

will be supported on 125 _m optical fibers in a combustion chamber where the ambient environment can be

controlled. The low-gravity testing will employ droplets suspended on 15/.tm Si-C fibers, a new technique

developed during the past year, again in a combustion chamber where the ambient environment can be changed.

TASK SIGNIFICANCE:

The eventual goal will be to use the results of this work as inputs for models on spray combustion, wherein

droplets seldom burn individually (the combustion history of a droplet is strongly influenced by the presence of the

neightx)ring droplets).

PROGRESSDURING FY 1994:

In collaboration with Dr. R. Vander Wal, data was obtained on the relative and absolute soot volume fractions

prcxluced during the burning of fiber supported droplets. The dam was of single droplets with a 1.5 mm initial

di_uneter suspended on optic',d fibers at 1 arm pressure in the atr. The fuels used were n-heptane, n-decane,

chloroheptane, chlorodecane and ethanol/de.cane mixtures. The data consisted of simultaneous measurements of the

soot w_lume fraction (via LID and natural flame images, simultaneous measurements of natural flame and OH

chemiluminescence, and simultaneous measurements of droplet size, flame radiation measurements, and natural

flame.

The modifications to the experimental apparatus were completed and initial burning rate data on single droplets of

pure fuels (decane, heptane, and methanol) with different size support fibers were taken. The effects of the support

fiber are being investigated by comparing the expertmental results to theoretical computations by M.

Vedha-Nayagam.

The normal gravity apparatus was recontigured for two droplet studies. Testing began on the combustion of two

droplets of n-decane (normal gravity).

This effort is "also part of the Fiber Supported Droplet Combustion Glovebox Experiment. The engineering model

of the experiment was built and tested. The flight hardware was designed and all of the parts were fabricated. All of

the paperwork to date is complete. The experiment is manifested on USML-2.

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11-269
If. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

,lllolulllomllolnoll j_u_n_i_|_on_F|;eI_"_o_D_oi|Io_H_oo_o_n_o_|_on_u_H_on_"nso_H_to_o_n_H_6_H_"_"_H_H _on_oo_oo_i_o_1_H_o_I"_I_D|_H_u_|u"_o_o_o_o_ooo_o_|_ooou

STUDENTSFUNDED UNDER RESEARCH: TASK iNITIATION: 10/89 EXPIRATION: 12/94

PROJECT IDENTIFICATION: 962-22-05-33

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Dietrich, D. "Relative soot volume fractions in droplet combustion via laser-induced incandescence." Eastern States

Section of the Combustion Institute Fall meeting, 1994.

Vander Wal, R. and Dietrich. D. "Laser-induced incandescence applied to droplet combustion." Applied Optics. 1994.

Vander Wal. R. and Dietrich, D. "Laser-induced incandescence applied droplet combustion." Western States Section of the

Combustion Institute, Spring Meeting. 1994.

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II-2 7 0
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

l uH n_e a_1 aaoaronllniaf aJ onranHnu J I aopaoanul I I II II I I I I nonnlan.allnllulqnHno I ooI hal i i no nn_anlonllnlo ooonnoa IuI I I II I II I Ill g# I I I I I II I II I I III If Ing i i ii I Oll onaomgoolno DIll ni na|Hao l aoo|o IIOl i iiiii I aon I IIIIO i ill oiiiii I IOnl oooaorta oon go i aanougaa iag i o

Internal and Surface Phenomena in Heterogeneous Metal Combustion

PRINCIPALINVESTIGATOR: Dr. Edward L. Dreizin AeroChem Research Laboratories, Inc.

CO-INVESTIGATORS:

Dr. H.F. Calcote AeroChem Research Laboratories, Inc.

TASK OBJECTIVE:

This project is an experimental and aria_Lyrical study to determine the mechanisms by which oxygen penetrates

within a burning metal droplet and affects the combustion process. Particular attention is given to disruptive

burning, such as m micro explosions, which have been observed but never explained by current theories.

TASK DESCRIPTION:

The study uses a novel apparatus that generates unilormly sized metal droplets through electrical arc discharges with

consumable, pure metal electrodes. The separated droplets are ignited and then subsequently quenched to terminate

the reaction at prescribed times during combustion. Experxmental measurements will cover droplet temperatures and

diameters as functions of time and chemical and metallurgical analyses of the quenched, solidified specimens. Test

conditions include variations of temperature, droplet size, and aunospheric oxygen concentration, for at least three

different metals. Initial normal gravity tests are conducted at the AeroChem Laboratories facilities. Subsequent

microgravity tests, using a modified version of the droplet generator apparatus, will be conducted by the

investigators in the Lewis Research Center free-fall drop tower facility. In microgravity, the near-absence of

settling forces permits the precise control of the droplet motion to improve the interpretation of the droplet-diameter

and droplet-temperature histories. Concurrent with the experimental studies, analytical studies verified by the

experimental results model the processes occurring in metal droplet combustion to provide a theoretical foundation

of surface and internal transport and reaction rate phenomena in the burning metal-droplet system.

TASK SIGNtFICANCE:

This project is a study of metal and oxygen behavior in metal-droplet combustion using a unique but demonstrated

apparatus to generate, control, and analyze the combustion processes. The results of the study have practical

application Io the performance and improvement of metallized fuels, such as those used in solid rocket motors.

PROGRESSDURING FY 1994:

This project began on July 6, 1994 with the award of NASA Contract NAS 3-27259. Since the basic apparatus for

metal-droplet generation and ignition, called the GEMMED, was available and operational, only minor

modifications to the apparatus were required prior to the studies. These changes, "already accomplished, included an

improved consumable wire-electrode feed unit with a measuring microscope and various small changes to the power,

gas-teed, and instrumentation systems.

The initial study used the GEMMED to generate aluminum (AI) droplets in three nominal diameters of 120 larn,

160 gin, and 190 _tm, for ignition and combustion in a normal-gravity, air environment. Temperature histories

were provided by three-wavelength optical pyrometry. Three stages of combustion were observed in the available

time for particle combustion (100 ms for the 160 Ixm particle diameter, for example). 1) An initial stage had

spherically symmetric combustion, with temperatures increasing to near the boiling point of A1203 and radiation

also increasing. 2) A second stage had non-symmetric combustion, with temperatures falling slightly but radiation

showing a peak and oscillations. 3) A final stage had non-symmetric combustion, with decreasing temperatures and

radiation.

Particles were quenched at different combustion times in the tests by allowing them to pass into an argon

atmosphere separated from the air by a soap-bubble film as well as by impingement. Cross-sections of quenched

I1-271
lI. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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particles were exanuned using scanning electron microscopy; interna.l composition was determined using

energy-dispersing spectroscopy. From the temperatures, composition, and observed smoke traces, the investigators

propose a mechanism for the combustion-stage transition based on the concentration of oxygen dissolved in the AI

particles. Further interpretations are being advanced to understand the nature of the final combustion stage and the

potential to create micro-explosions.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 6/98

PROJECT IDENTIFICATION: 962-22-05-46

NASACONTRACTNOI'_AS-3-27259

RESPONSIBLECENTER: LeRC

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II-272
Flame-Vortex Interactions hnaged in Microgravity

PRINCIPALINVESTIGATOR:Prof. James F. Driscoll University of Michigan

CO-INVESTIGATORS:

£rof. W.J.A. Dahm

Prof. M. Sichel

University of Michigan

University of Michigan

TASK OBJECTIVE:

The objective of this research is to investigate a method that will provide high quality, quantitative, color enhanced

digital images of a vortex exerting aerodynamic strain on a flame under microgravity conditions. This will be used

to:

1. Quantify how the vortex distorts the flame;

2. Define the degree of flame curvature;

3. Show how preferential diffusion affects temperature profiles.

TASK DESCRIPTION:

The fundamental interaction between turbulence and chemistry in a combustion process will be studied by

interacting a repeatable, well-delLned vortex, or variable size and strength vortex, with premixed and nonpremixed

flames. The complicating effects of buoyancy will be eliminated by employing the NASA LeRC 2.2-second drop

tower. High quality, quantitative, color enhanced 2-D images will be obtained of the temperature field, the flame

emission, and the mixture fraction (nonpremixed case). Results will be compared to full Navier-Stokes direct

numerical simulations and to the classical theory of stretched flames.

TASK SIGNIFICANCE;

Images of the flame shape and curvature will be used to assess numerical simulations which neglect buoyancy, and

to deduce universal, buoyancy tree scaling relations showing the effects of vortex size and strength. Understanding

of turbulent combustion, applicable to "all practical combustion, will be enhanced.

PROGRESSDURING FY 1994:

During the month of June a student was hired and was assigned the task of building and testing an array of Thin

Filament Pyrometers, which is one of the diagnostics to be used on the drop tower experiment. A method was

developed to mount 50 SiC filaments for thin filament pyrometry with the proper tension. The necessary flow

metering equipment for the calibration burner was purchased and assembled. An intensified CCD array camera is

being used to Image the radiated light intensity from the 16 rmcron diameter filaments at two wavelengths, from

which temperature is to be deduced. Also, during the month of June some of the necessary software was written

and an orientation visit from Jim Driscoll, Werner Dahm, Chuck Mussel, and Ron Springer, took place on 24 June

1994. A tour of the NASA LeRC 2.2-Second Drop Tower and SEL was conducted.

During the month of July a CCD array camera was used to image 10 thin filaments to determine the 2D temperature

field in a flame, a method to be used in future drop tower tests. Images were obtained and the reduction of the data

was begun. Software development is continuing in order to deduce the temperature and to apply small corrections

for conductive and radiative losses along the filament. The survivability of the filaments was tested and a way to

separate many filaments from the initial filament bundle was developed, using acetone and water solutions.

Dr. King from NASA Headquarters recommended that we interact with modellers in the NASA microgravity

program, so we contacted Prof. Elghobashi fl'om the University of California at lrvine, who agreed to provide

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II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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computations of unsteady strained flames with full chemistry and radiative losses. We will use his computations

for comparison to our future data. to determine if the flamelet modeling approach is a valid approach. We also plan

to work with Dr. K. Kailasanath, IYom NRL, who is doing direct numerical simulations of microgravity flames.

We agreed to plan our joint programs to provide overlapping conditions, whenever possible. It appears that our

experiment should be especi'ally useful for the Large Eddy Simulation models, such a.q the one presented by Dr.

Kailasanath at the Symposium. This model uses Direct Ntanerical Simulation to solve the exact Navier Stolkes

equations down to a certain grid scale, then applies a subgrid model to stmulate the smallest scale phenomenon.

We can provide measurements that are needed to develop the subgrid model, which is based on flame-vortex

interactions.

During the month of August the research team met to plan the design of the drop tower experiment and arrange for

the integration of the experiments and the model to be developed. A preliminary design of the experiment to be

dropped was sketched out. Vendors were contacted to obtain intormatton regarding the sizes of light sources,

cameras, electronics and fuel tanks. Calculations were performed to determine the feasibility of certain diagnostics,

including white light PIV, Mie imaging using oil drops, and thin filament pyrometry. Efforts also are being made

to improve and apply the software needed for the PIV and Mie imaging diagnostics. Software development is

progressing while the experiment is being designed and fabricated.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 4/98

BS Students; 0 PROJECT IDENTIFICATION: 962-22-05-45

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 2

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11-274
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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Aerodynamic, Unsteady, Kinetic, and Heat Loss Effects on the Dynamics and Structure qf

Weakly-Burning Flames in Micrograv#y

PRINCIPALINVESTIGATOR:Prof. Fokion N. Egolfopoulos University of Southern California

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

To obtain quantitative information (flame speed, velocity field, temperature) about the characteristics of weakly

burning flames in microgravity, and to apply this information to analyze near-limit phenomena at normal gravity

conditions.

TASK DESCRIPTION:

The expertments will employ a counter-Ilow burner geometry to provide a nearly adiabatic flame with a

well-controlled strain, for conditions that cannot be achieved in normal gravity. Both premixed and diffusion flames

will be studied at various pressures, and Laser Doppler Velocimetry, Particle Image Velocimetry and high-speed

cinematography will be used to measure the flow fields. Models will be developed for these cases for comparison

purposes, In addition, flame interactions will be studied, and numerical stmulations of flame propagation m tubes

in spherical vessels will be performed. Experiments will be conducted at normal gravity, in the NASA LeRC

2.2-Second Drop Tower, and aboard the NASA aircraft.

TASK SIGNIFICANCE:

The research will allow a first-tune study of flames burning near their flammability limit (the concentration of fuel

in air that just forms a flammable mixture) without the complications of buoyancy, wall heat losses, or

time-varying strain. It will provide fundamental data about the flammability limits that can be used to verify

theoretical calculations, and has applications to turbulent combustion such as that found in engines.

PROGRESSDURING FY 1994:

This is a new prqject, so effort h&_ thus lar been concentrated on defining the order of the experiments and designing

hardware. Design and drawings for the countertlow burner apparatus have been completed, and construction is

underway. Layout of the hardware in a drop frame for the 2.2-Second Drop Tower, testing of a new flame ignition

system, and design of a PIV test rig are underway.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 1

TASK INITIATION: 5/94 EXPIRATION: 4/98

PROJECT IDENTIFICATION: 962-22-05-50

RESPONSIBLECENTER: LeRC

11-275
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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Effects of Gravity on Sheared and Nonsheared Turbulent Nonpremixed Flames

PRINCIPAL INVESTIGATOR:Prof. Said E. Elghobashi University of California, h'vine

CO-INVESTIGATORS:

Dr. Y.Y. Lee

Mr. R. Zhong

University of California, Irvine

University of California, Irvine

TASK OBJECTIVE:

The objective is to answer fundamental questions regarding the effect of buoyancy on turbulent combustion. These

questions include the tollowing:

1. How does buoyancy affect the small-scale structure of the scalar and velocity fields?

2. How does buoyancy affect the distribution of scalar dissipation near the reaction zone?

3. Under what conditions is the tlamelet model valid for buoyant turbulent diffusion flames?

4. How does flame extinction depend on the appropriate non-dimensional numbers (Fr, Da, Re, etc.), the

magnitude of the reaction energy, and the direction of gravity, relative the fuel-air interface?

TASK DESCRIPTION:

This research is entirely computational. It will focus on direct numerical simulation (DNS) of two cases of flow:

in initially isotropic turbulent flow (without shear) and a flow with initially uniform shear. In both cases, separate,

parallel streams of fuel and oxidizer will enter the computational domain and react. Numerical models that have

'already been developed by the Principal Investigator will be extended to these cases with principal additions to

include finite rate chemistry and non-zero gravity. The results will be condensed in the form of diagrams based on

the appropriate nondimensional numbers.

TASK SIGNIFICANCE"

This work will answer fundamental questions regarding how buoyancy induced by gravity affects turbulent

combustion. In particular, gas, temperature, and velocity distributions can be very different in the absence of

gravity, and this research will focus on revealing the small-scale structural differences in the flame, as well as

probing the dependence of flame extinction on the alignment between gravity and the fuel-air interface. With this

informauon, mathematical models of turbulent diffusion flames can be modified to better account tor buoyancy

effects. Better understanding of the physical processes will lead to improved combustor designs and enhanced

predictive capabilities regarding fires on Earth and in a space environment.

PROGRESSDURING FY 1994:

This is a new research effort. Thus far, the partial derivative terms in the existing computer code have been

modified from 2rid order central differences to 5th order and 6th order accurate schemes and the results checked against

the exact solution of the Taylor-Green vortex flow. The conclusion was that while the new approach yielded more

accurate results, the increase in computer time was not acceptable. Current efforts are under way to rewrite the code

so that it can take advantage of new parallel processor computers, and to continue code additions to include finite

rate chemistry and buoyancy forces.

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!1.-276
STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 5/98

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-59

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

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II-277 ___.
II. MSADProgramTasksm Ground-based Research Discipline: Combustion Science

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Combustion of Electrostatic Sprays of Liquid Fuels in Laminar and Turbulent Regimes

PRINCIPALINVESTIGATOR:ProL Alessandro Gomez Yale University

CO-INVESTIGATORS:

Prof. M.B. Long

Prof. M.D. Smooke

Yale University

Yale University

TASK OBJECTIVE:

This research is a combination of experimental and computational work by Professors Alessandro Gomez (PI,

experimental), Marshall B. Long (Co-I, diagnostics) and Mitchell D. Smooke (Co-I, computational), all from Yale

University. It involves studying the formation and burning of electrosprays of liquid fuels at both normal and

reduced gravity.

TASK DESCRIPTION:

Normal-gravity testing of electrostatic sprays is conducted with cold-flows (i.e., non-buoyant) and in counter/low

diffusion flames. Microgravity tests of the counterflow diffusion flame are conducted in the NASA LeRC

2.2-Second Drop Tower. A numerical model of a gas-phase counterflow diffusion flame is being extended to

account for the droplet spray, for comparison of predictions with experimental results.

TASK SIGNIFICANCE;

The goal of this investigation is to study the combustion of well-defined and well-controlled sprays in

configurations of successively increasing levels of complexity, starting from laminar sprays to tully turbulent ones.

This may lead to improvements in the design of diesel engines or liquid-fueled rocket engines.

PROGRESSDURING FY 1994:

The FY94 research effort was focused on three areas: (l) tests with electrostatic sprays, (2) tests with sprays

produced by an ultrasonic nebulizer, and (3) the development of laser diagnostics for droplet size measurements.

There were no microgravity tests conducted in FY94 due to the shut-down of the NASA LeRC 2.2-Second Drop

Tower.

(1) Experiments with Eiectrosprays

Normal-gravity tests were conducted with an electrostatic spray of heptane in an axisymmetric, laminar, diffusion

flame. The flames were like a candle flame in appearance (i.e., sheath combustion), with a dark core (where the

droplets evaporate without burning), surrounded by a high-temperature soot-shell, enveloped by the blue flame.

There was no evidence of individual droplet combustion. The results (based on phase Doppler anemometry and

sizing, as well as thermocouple measurements) indicate that the D-square law with constant evaporation rate was

satisfied over a significant portion of the droplet history. It was lound that the average evaporation rate could be

determined from the height of the dark core without intrusive measurement. It was also observed that

droplet-droplet interactions, although present near the flame surface, were apparently not significant in the flame

core.

(2) Expernnents with Sprays Produced by an Ultrasonic Nebulizer

Preliminary normal-gravity tests were conducted with an ultrasonic spray, since the electrostatic spray does not

allow studies of/lame extinction and droplet interaction under low-slip conditions (which are more amenable to

numerical modeling). Preliminary. tests indicate that the mean droplet diameter is independent of flow rate and

controlled by the resonant frequency of the piezoelectric crystal. Good size distributions have been attained (with a

relative standard deviation less than 0.3), although the droplets are not monodisperse as with the electrospray. A

self-sustained fiat flame has been established over a much wider range of conditions than possible with the

electrostatic spray (e.g., 2 cc/min and a strain rate of 30 s-l), and work is underway to improve the burner stability.

The researchers are now considering how to adapt the ultrasonic burner to the 2.2-second drop package.

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11-278
I[. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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(3) Development of Laser Diagnosucs

Improvements have 'also been made in the mea_surement of droplet size. By matching the angular scattering pattern

with calculations for spheres from Mie-Lorentz theory, size determination has been improved from an accuracy of

4% to 1% in droplet diameter ( 12_ to 3% in volume). Since the comparison of the measurements with Mie-theory

calculations is very tune-consuming, algorithms were developed based on FFT to generate a look-up table

associating scattering patterns with measurements. The sensitivity of the technique to the effecLs of finite laser

beam size will be investigate in the future. A paper describing the technique is being prepared for submission to

Applied Optics.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 3/91 EXPIRATION: 12/98

PROJECT IDENTIFICATION: 962-22-05-34

RESPONSIBLECENTER: LeRC

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I1-279
Three-Dimensional Flow in a Microgravity Diffusion Flame

PRINCIPALINVESTIGATOR: Prof. Jean R. Hertzberg University of Colorado, Boulder

CO-INVESTIGATORS:

Mark A. Linne Colorado School of Mines

T_SK OBJECTIVE:

The objective is to study the influence of buoyancy on the three-dimensional fluid dynamics of the interaction

between a diffusion flame and the elliptic vortex rings lormed by pulsations of the fuel flow issuing from an elliptic

nozzle.

TASK DESCRIPTION;

A methane diffusion flame burning in atmospheric conditions is investigated. Elliptic vortex rings are generated by

a combination of periodic flow perturbations (active forcing) and the elliptic geometry of the fuel nozzle (passive

forcing). The fuel flow is forced by an in-line 100 watt louckspeaker system at frequencies up to 1 Khz. Phase-locked

flow visualization and particle image velocimeu'y _PIV) are the primary diagnostics.

T_SK SIGNIFICANCE;

Techniques to control turbulent structures in flames are investigated with the objectives in mind such as enhancing

combustion efficiency and reducing pollutant lormation using techniques of active and passive control of fluid

dynamics. Potential applications include industrial and residential burners and gas/liquid fueled engines.

PRO6RESSDURINGFY 1994:

Preliminary test plans and schedule were prepared and presented to LeRC's drop tower and diagnostics personnel.

Normal gravity studies on the prototype combustor revealed that the flow exhibits a bifurcation type phenomenon

in the absence of flame. A nonreacting flow of air was visualized using cigarette smoke and alumina particles,

illuminated by a strobe, phase-locked to the lorcing signal. The results show that the acoustically forced jet forms a

series of vortex rings which evolve into a complicated structure, which then splits into two or three jets several

diameters downstream of the nozzle exit. Preliminary results suggest that this phenomenon exists over a wider range

of flow rates and at lower forcing levels than the bifurcated flame phenomenon. The effective frequency range Ior the

nonreacting air flow is also wider and lower than the flame phenomenon. The presence of the bifurcating

phenomenon in a nonreacting air flow suggests that the driving mechanism is not an absolute instability, but is

more likely a combination of axial and azimuthal forcing.

Efforts have begun to visualize the fuel jet in the bifurcated flame case. Note that techniques developed for the

bifurcated flame will be applied to the asymmetric forced flame as appropriate. The fuel flow was seeded with

aluminum oxide as in the previous non-reacting air flow, using a cyclone/fluidized bed seeder. A white-light strobe

was phase-locked to the torcing signal. However, the flame emission was several times more intense than the light

scattered by the seed, so further development of this technique is needed. As a tirst step, the experiment rig was

moved to a different room, where a 12 watt argon ion laser is available. This laser will be chopped with a chopper

wheel and attempts will be made to phase-lock it to the torcing signal. If this is unsuccessful, a Bragg cell based

chopping system can be developed. Eventually, a diode laser system is planned in place of the (large) ion laser.

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II-280
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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STUDENTSFUNDED UNDER RESEARCH:

BS Students: 6

MS Students: 0

PhD Students: l

TASK INITIATION: 5/94 EXPIRATION: 5/98

PROJECT IDENTIFICATION: 962-22-05-58

RESPONSIBLECENTER: LeRC

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II-2 81
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

Chemical Inhibitor Effects on Diffusion Flames in Microgravity

PRINCIPALINVESTIGATOR:Prof. Simone Hochgreb Massachusetts Institute of Technology (MIT)

CO-INVESTIGATORS:

Gregory Linteris National Institute or' Standards and Technology (NIST)

TASK OBJECTIVE:

The objectives of the proposed research are as follows:

1. To determine the effects of flame inhibitors on the physical characteristics (height, shape, color, and luminosity)

and stability limits (ignition, extinction, lift-off and blow-off) of gaseous diffusion/lames in the presence of

halogenated fire suppressants in microgravity.

2. To develop quantitative analytical models lbr the observed behavior, including chemical kinetic effect.s, in order

to understand the mechanisms of inhibition of halogenated compounds in gaseous diffusion flames.

TASK DESCRIPTION;

The experiments will consist of normal and microgravity studies of laminar jet and co-flow diffusion flames

inhibited by halogenated suppressant addition to the air or fuel stream. In microgravity, visual and temperature

diagnostics will be utilized to detect flame shape, dynamics and stability limits. Normal gravity experiments will

make use of additional chromatographic and spectroscopic diagnostics in addition to visual and temperature

experiments.

Analytical and computational work will be performed using existing general 2-D codes with chemical kinetic

models for comparison with the observed results. The calculations should serve for comparison with observations,

explanation of observations and selection of additional experimental conditions of interest.

TASK SIGNIFICANCE:

Fire suppression in space is one of the main reasons to investigate combustion phenomena in microgravity. Since

halogenated compounds will remain as the tire suppressant of choice in many space missions, there is clearly a need

for experunental evidence on the effectiveness of these compounds under zero buoyancy conditions.

The final product of the expe_nental and analytical work is a comprehensive and quantitative understanding of the

physical and chemical phenomena involved in the suppression of diffusion flames through the addition of chemical

halogenated inhibitors. This understanding is expected to be veD* useful both from a fun "darnental viewpoint as well

as for the practical utilization of chemical fire suppressants in space.

PROGRESSDURING FY 1994:

In order to tirst examine the effects of the inhibitors CF3H and CF3Br on diffusion/lames in normal gravity we

constructed a co-flow diffusion flame burner capable of operation with variable .jet diameters. C',.dibrated mass flow

controllers under computer control metered the flows of air, fuel gas (propane and methane), and inhibitor. Two jet

diameters were used in the current experiments (0.1 mm and 1.2 ram). The smaller jet produces a flame 0.3 to 0.7

cm tall, and the larger jet 14 to 16 cm. Because of the flame's small size, the effect of buoyancy will be less using

the smaller jet, allowing some early assessment of the effects of buoyancy on the flame characteristics.

In these tests, we ftrst determined the flow rate of methane necessary to cause blow-off for each jet diameter, and

determined the effect of the air co-flow velocity on the blow-off condition. It appeared that the blow-off condition

was sensitive to the aerodynamic conditions near the jet tip which were affected by the co-flow velocity and any

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geometrically induced llow disturbances. We then measured the concentration ot CF3H and CF3Br which caused

blow-off at a methane flow rate of 50_ of the fuel blow-off condition for these two jet diameters. The results of the

experiments will help us to determine the initial test conditions of the NASA LeRC 2-Second Drop Tower tests in

the presence of inhibitor. We next recorded video images of the flames as a function of either the fuel flow rate or

the inhibitor concentration in the air stream, and used these to determine the flame height. These data can be used to

assess the utility of simple analytical models for predicting the flame size.

An important component of the present project will be calculations of the flame structure using a detailed chemical

kinetic mechanism and a suitable flame model. This month we acquired a kinetic mechanism/or fluorine inhibition

of hydrocarbon flames from BurgessFl'sang/Zachariah/Wesunoreland at the National Institute of Standards and

Technology (NIST) and combined it with GRIMECH obtmned from Greg Smith at SRI. Using the premixed flame

code of SANDIA, we have perRmned extensive tests of its performance against premixed flame speed measurements

recently obtained as NIST and MIT.

1) Measurements of the effect of CF3H and C_Fe on CH, laminar flame speeds in a combustion bomb at variable

pressure and temperature have been concluded. The experimental data, at equivalence rations of 0.8 to 1.2, pressures

between 0.7 and 8 atm and temperatures between 300 and 500 °K show that, as shown for experiments at ambient

conditions, both inhibitors are more effective at rich conditions, CzF_ being twice as effective as CF_Br. No

particular dependence of the inhibition effect on temperature or pressure is apparent, the effects being primarily a

function of inhibitor concentrauon (tested between 0 and 5 percent) and equivalence ratio, results are currently being

prepared tbr publication.

2) The chemical kinetic mechanism developed at NIST/or CF_H and C2F 6 inhibition effects was used to predict

flame speeds at the varying pressure and temperature conditions/or which the tests were conducted. The results

show remarkable agreement under lean conditions, but predictions are 10-15 percent lower than observed values at

the richest equivalence ratio. This leads us to conclude that some difficulties are potentially to be expected in

modeling diffusion flames, where much of the chemistry takes place under rich fuel conditions.

3) Belbre we are able to use the NIST fluorinated species inhibition mechanism to model our inhibited methaneand CO-air diffusion flames, we must first test the accuracy of the mechanism. Towards this end, we have begun

testing the mechanism against bolh data collected at NIST and with data existing in the literature. This month we

performed extensive calculations of the llame structure of premixed methane-air and CO-O2-Ar flames inhibited by

CF3H. The methane calculations were performed at phi=0.9, 1.0, and 1.1 for inhibitor mole fractions up to 8_,

and these were compared with recent measurements at NIST. The NIST mechanism was Iound to predict several of

the unportant features of the CF3H inhibition, including the strong effect of equivalence ratio on the burning rate

reduction (rich flames are inhibited more), and a reduction in inhibitor effectiveness at higher inhibitor mole

fractions. The kinetic mechanism, however, is predicting about 30_ more reduction in burning rate than the

experiments show. We have been working closely with Wing Tsang and Don Burgess to try to determine the

possible areas for improvement m the mechanism.

4) In order to test the effectiveness of CF3Br and CF3H in micro-gravity under non-sooting conditions, we plan to

study inhibited CO flames. The burning rate reduction of premixed CO-O2-Ar flames by CF3H has been measured

by Vandooren and co-workers. To test the model lbr moist CO oxidation, we have perfonned numerical calculations

of the burning rate for all of Vandooren's conditions (about 150 flames). In nearly all of these calculations, the

burning rate was predicted within I0'_. (flames with very low H2 concentration were not well predicted). Hence, it

appears that the model works vcryIundcrlined) well for moist CO flames, but may need more work for CH4 flames.

5) We have started to set up a counter-flow diffusion flame lor studies of CF3H and CF3Br inhibited diffusion

flames, again, to test the mechanism, and to start to examine the mechanism to study the effects of transport on the

inhibition.
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/98

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-54

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 2

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11-284
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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Time-Dependent Computational Studies q{ Pre-Mixed Flames

PRINCIPALINVESTIGATOR: Dr. K. Kailasanath Naval Research Laboratory (NRL)

CO-INVESTIGATORS:

Dr. G. Patnaik

Dr. E.S. Oran

Berkeley Research Associates

Nav',d Research Labs

TASK OBJECTIVE:

Study the structure (multidimensional) and dynamics (propagation, stability and extinction) of premixed flames in

microgravity and normal gravity environments.

TASK DESCRIPTION:

Perform detailed numerical simulations using time-dependent, one-dimensional and two-dimensional flame models.

These models solve the multispecies-coupled, partial-differential, reactive-Ilow equations, including fluid,

thermodynamic and transport properties, chemical kinetics, radiative heat transfer, buoyancy and boundary heat loss

effects. The investigator will a) systematically isolate and evaluate the relative importance of v,'mous physical and

chemical processes that may be controlling the structure and dynamics of premixed flames, and b) compare

qualitatively and quantitatively with experimental observations. 1

TASK SIGNIFICANCE:

Small amounts of fuel leaking from fuel cells could pose a tire hazard on the space-shuttle and similar vehicles.

Therefore, understanding the burning and extinguishment characteristics of flames are important lot the sale

operation of space vehicles. The knowledge gained from such studies is "also useful lbr the sale and efficient use of

fuels on Earth. Computer simulations are a cost effective way to obtain data to corroborate limited experimental

observations and provide additional details which are difficult to obtain from space based expertrnents.

PROGRESSDURINGFY 1994:

Investigations of burner-stabilized lean methane-air flames indicate that a 5% methane-air flame cannot be stabilized

even by including the effects of radiative losses. This is in contrast to freely-propagating flames which can be

sustmned in this mixture, with and without the inclusion of radiative losses. However, a 5.5% methane-air flame

can be stabilized on a burner, but only for high inflow velocities such as 7 cm/s, which is close to the

freely-propagating burning velocity. When the inflow velocity is reduced to 6 orals, the flame shows a longitudinal

oscillation with excursions of the flame temperature above and below the planar adiabatic values and eventually dies.

These oscillations are independent of the spatial and temporal resolution of the numerical solution. They appear to

be a manifestation of the transition from the imposed initial condition of a propagating flame to its stable no flame

final condition. However, these oscillations do not seem to be very significant physically since the flames

eventually die. For lower inflow velocities, the flames extinguish more quickly. Overall, the simulations suggest

that conductive and radiative heat losses play an important role in the stability of very lean methane-air flames and

that such flames can be stabilized on burners only for a narrow range of inflow velocities.

Some of the characteristics of freely-propagating low velocity lean methane-air flames are quite distinct from those

of lean hydrogen-air flames with similar velocities. The methane flames are thinner and have significantly higher

flame temperatures.

The cellular structures observed in lean methane-air mixtures (5-6%) were very weak when compared to those in lean

hydrogen-air flames of comparable burning velocities. Therelbre, after discussions with Prof. Paul Ronney, a CO2

diluted methane-oxygen mixture, with an effective Lewis number of about 0.70, was chosen for studying a case

which should exhibit strong cellular structures. Both the simulations and Ronney's experiments indeed indicate well

defined cellular structures. However, the detailed structures are not quite the same in the two cases. Computed

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11-285
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

burning velocities are larger than the expertmental ones; however, the flame temperatures are about the same.

Three-dimensional effects, insufficient numerical resolution and inadequacy of the chemical kinetics scheme to

adequately capture the effects of CO2 dilution are possible explanations tbr the observed differences.

The variation of the burning velocity with dilution is being studied to see if the "skeletal" mechanism used in the

computations is adequate to represent the chemical effects of dilution with CO2. This work is hampered by the lack

of experimental data on CO2 dilution effects. Further tests with N2 dilution are underway to check if the reaction

scheme is adequate for any dilute mixture. Tests in which the equivalence ratio was varied showed that the scheme

was adequate for tho_ cases.

Three-dimensional simulations as well as simulations using more complex chemistry schemes will need parallel

processing to be efficient. One of the major problems in achieving efficient parallel processing is distributing the

work-load among the various processors. The first step towards the development of a flame code that will

efficiently run on massively parallel processors such as the Intel/IPSC 860 was to develop a load-balancing

procedure for the chemistry. This has been accomplished using the newly developed Work-Patti software from the

University of Maryland. 'Stiff points are gathered into a 1-D array, and only those points are redistributed to other

processors using gather/scatter operations. This tends to reduce the number of points needed to be moved to achieve

the load balance. After tackling the chemistry, the FCT fluid convection, radiation, inflow velocity control and

timestep control routines were rewritten to make it more efficient and reduce the scratch space. David Fyfe (NRL)

and Craig Douglas (IBM) were instrumental in re-writing the multigrid part of the code for parallel implementation.

Then, the diffusive transport modules were also parallelized.

The development and testing of a fully parallel version of the flame code has been completed successfully. The code

has been run on the Intel/IPSC 860 at NRL and the lntel Paragon at Air Force Wright Aeronautical Labs and shown

to produce the same results as on the Cray C-90.

The newly developed parallel version of the flame code is being used to study the detailed dynamics of the

extinguishment of downward-propagating methane-air flames. The plan is to compare these observations to those

made in the earlier NRL study of the extinguishment of hydrogen-air flames. Such a comparison will be helpful in

isolating effects that are specific to the highly diffusive and easily combustible hydrogen-air mixtures from those

that are more general and applicable to a variety of fuel-air mixtures. Furthermore, it will also provide some

information on the relative role of conductive and radiative heat losses in extinguishing flames propagating in tubes.

The earlier NRL studies of one-dimensional, zero-gravity flames in lean methane-air mixtures showed that radiative

losses alone can extinguish some flames. In this study of two-dimensional flames, radiative and conductive losses

will be considered together and separately to isolate their effects. The NRL simulations to date show that a 5%

methane-air flame propagates without extinguishment even when considering both losses, so leaner mixtures will

be tried next.

Currently, studies of near limit downward-propagating methane flames are continuing. Discussions with Prof. Paul

Ronney and others at the International Combustion Symposium identified the third-body efficiencies in the

chemistry scheme as a possible source of the differences observed earlier between Paul's results and ours for the

extinguishment of CO2 diluted methane flames. It was decided to pursue this matter further using the FLAME1D

code before performing more detailed multidimensional simulations of the extinguishment of methane-air flames.

Different values for the third body efficiencies suggested in the literature have been incorporated into the codes. A

repeat of stoichiometric methane-air flames shows that these parameters do not make any difference in the results.

However, a repeat of the simulations of the CO2 diluted mixtures used in Paul's experiments shows that these

parameters have a strong influence on the flame temperatures and velocities. In fact, it has been difficult to even

ignite some of these mixtures. Our results to date show that the burning velocities of near-limit CO2 diluted

mixtures are now lower than prof. Ronney's. Recall that with the efficiencies set to unity, our burning velocities

were higher than those observed in his experiments. It appears that the exact values of the third body efficiencies

could play a crucial role in obtaining accurate results. It is not clear how accurately these parameters are known.

Preliminary calculations with a 5% methane-air mixture now show that it is very difficult to obtain a steadily

propagating flaee in this mixture when radiation and non-unity third-body efficiencies are taken into account.

Further calculations are being perlormed to resolve this issue.

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11-286
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 2/92 EXPIRATION: 12/97

PROJECT IDENTIFICATION: 962-22-05-22

RESPONSIBLE CENTER: LcRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Patnaik, G. and Kailasanath, K. On the role of gravity in burner-stabilized flames, The Eastern States Section of the

Combustion Institute. Chemical and Physical Processes in Combustion, 417-420 (Oct.25-17, 1993).

Patnaik, G. and Kailasanath, K. Effect of gravity on multidimensional burner-stabilized flames, in Heat Transfer in

Microgramity, eds. C.T, Avedisian and V.A. Arpaci, HTD, the American Society of Mechanical Engineers. New York. NY.

vol. 269. 79 (1993).

Presentations

Patnaik, G. and Kailasanath, K.

Meeting, New York, NY, 1993.

"Effect of gravity on multidimensional burner-stabilized flames." ASME Winter Annual

Patnaik. G. and Kailasanath. K. "Celleular structure of lean hydrogen and methand flames." ASME Winter Annual

Meeting, New York, NY, 1993.

Patnaik, G. and Kailasanath, K. "Numerical simulations of burner-stabilized hydrogen-air flames in microgravity." the

25th Int. Symp. on Combustion, lrvine, CA, July 31 - August 4, 1994.

Patnaik. G. and Kailasanath, K. "Cellular structure of lean hydrogen and methane flames." AIAA 94-3275, 30th

AIAA/ASME/ASEE/SAE Joint Propulsion Conference, Indianapolis, IN. June 27-30, 1994.

Patnaik, G. and Kailasanath, K. "Numerical simulations of burner-stabilized hydrogen-air flames in microgravity."

presented at the 25th Int. Symp. on Combustion, Irvine, CA, July 31 - August 4, 1994.

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11-287
If. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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Radiative Ignition and Transition to Flame Spread in Microgravity

PRINCIPALINVESTIGATOR: Dr. Takashi Kashiwagi National Institute of Standards and Technology (NIST)

CO-INVESTIGATORS:

Dr. H. Baum

S.L. Olson

National Institute of Standards and Technology (NIST)

NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The objectives of the Middeck Glovebox RITSI Investigation is to conduct an experimental study of the radiative

ignition and subsequent transition to flame spread in low gravity in the presence of very low speed air flows in 2D

and 3D configurations and to compare the experimental observations with the theoretical model.

Although the fundamental processes involved in radiative ignition have been suggested in the literature, there have

been no definitive expertmental or modeling studies up to this point due to the flow motion generated by buoyancy

(starting plume problem) near the heated sample. In addition, there are very few studies of the transition from

ignition to flame spread. Almost all flame spread studies are based on two--dimensional, quasi-steady or steady

flame spread. The limit on the viability of flame spread should be controlled by the transient process from ignition

to flame spread. Steady- state flame spread models cannot be expected to accurately describe this limit.

For the first time the use of a prolonged microgravity environment allows us time to conduct a definitive study on

ignition and subsequent transition to flame spread. The model and numerical codes for such a calculation are

nearing the end of their development, and experimental data is needed to compare with the predicted results. From

the comparison, we will learn how accurately we understand ignition and flame spread mechanisms and where the

deficiencies in our understanding of them might exist.

TASK DESCRIPTION:

RITSI hardware uses a localized irradiated area via a radiant heater and/or hot wire to ignite samples of cellulose of

various thickness and/or composition. The hardware will provide a means to record ignition delay time and the

subsequent transition to flame spread at various low speed air flows. It will also provide a means to record solid and

gas-phase temperature data as well as the radiant heater and flow information.

Variables in priority order are 1) Flow velocity (0,2,5 cm/s); 2) Irradiated sample diameter (1 cm, 2.5 cm) and/or

power level (up to 8 W/cm'-) 3) Smoldering via metal ion doping of fuel 4) Geometry of sample (2D or 3D) and 5)

Sample thickness.

RITSI hardware consists of a flow duct with screens at both ends and a tan (pulling air through duct rather than

pushing it) at one end along with an area reducer to provide the air flow. One side of the duct opens tot access to

the sample holder for changeout of samples in the glovebox, Some samples are narrow rectangles, for upstream and

downstream propagation only, and some will be more square, for propagation sideways as well.

TASK SIGNIFICANCE:

In previous studies, ignition and flame spread were studied separately with the result that there has been little

understanding of the transition from ignition to flame spread. In spacecraft tire safety applications this transition is

crucial to determine whether a t-tre will be limited to a localized, temporary burn or will transition into a growth

mode with the potential to become a large fire.

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PROGRESSDURINGFY 1994:

(October 1993) RITSI: Formal approval from NASA HQ baked on the September nonadvocate peer review wa_

received for continued development of a Glovebox experiment called RITSI (Radiative Ignition and Transition to

Spread Investigation). The engineering unit assembly is beginning electrical assembly.

(November 1993) Theoretic',d study: the variable mesh c(xle is working and quiescent three-dimensional calculations

are being run. RITSI: The engineering unit assembly is complete and calibrations are underway in preparation for

December Learlet low gravity testing.

(December 1993) RITSI: Six Leafier flights with 14 tests were successfully conducted. Ignition of plain Whatman

44 was not achieved with the lamp alone, and m(xlifications to the ignition procedure "allowed for successful ignition

with a soot spot and gas-phase pilot in addition to the lamp. Smolder-promoted paper ignited easily.

(January 1994) RITSI: Data analysis of the Learjet tests by LeRC personnel is underway in preparation for a visit

to NIST by LeRC's S. Olson.

(February, 1994) Theoretical: Axiymmetric cases were run with a variable step size, and the results documented in a

Combustion and Flame paper (1994). RITSI: Preliminary results of the Leariet tests were presented to NIST

during a February 17 visit by S. Olson. Flight hardware design has started.

(March 1994) Formal approval of a NRA-submitted proposal was received by the PI from NASA HQ. A flight

experunent as a follow-on to the precursor RITSI Glovebox experiment is approved. This experiment is tentatively

entitled TIFS-3D (Transition from Ignition to Flame Spread in 3D). The Lewis team (Project Scientist and Project

Engineer) were assigned. Theoretical: A pilot ignitor in the gas-phase was added to the code. Variations of the

incoming velocity distribution are being studied. RITSI: Odor testing was conducted. Data analysis and upgrades

of the engineering hardware continue.

(April 1994) Theoretical: Numerical computations have been run to evaluate the effect of energy distribution on the

ignition and transition to flame spreading quiescent environments. Spot size and total energy were varied, and the

results indicate that although the final flame spread rate is independent of energy distribution, the ignition delay and

the transient spread rate from ignition to steady state are strong functions of the energy distribution. RITSI: Flight

hardware design is nearly complete. Engineering testing of ignition delay and ignitor wire temperature was

conducted. Negotiations for tesung of the Engineering Unit at Brunel to determine production levels of CO and the

Glovebox facility's ability to convert the CO to CO_ were initiated. TIFS-3D: Project team reviewed proposal.

Negotiations with Japan were initiated on a collaboration to conduct tests with the RITSI Engineering hardware in

the 10 second Hokkaido JAMIC facility.

(May 1994) Theoretical: 2D flame ignition and subsequent flame spread of a finite-width (uninhibited edges)

thermally-thin paper were calculated with no wind. The results showed that the flame spread rate at the edge is at

least twice as fast as the spread rate in the center of the paper. RITSI: Toxicity testing of the smolder-promoted

paper for CO is being prepared at NIST. The output of the radiant heat lamp was experimentally characterized.

TIFS-3D: Olson attended the kickoff meeting for the new flight NRA's. An Objective and Scope for TIFS-3D

were drafted.

(June 1994) RITSI: Electrical and mechanical upgrades to the engineering hardware were complete. Verification

documentation for the flight experiment was drafted. Additional lamp characterization tests were conducted. Status

was reviewed with the PI during a visit by the PI on June 3. TIFS-3D: A memo was sent to HQ by the PI and

Project Scientist requesting an expanded scope for the TIFS-3D experiment to include 02 and preheating effects.

The PI visited the project team on June 3 to define the experiment objectives, scope, draft matrix, and diagnostics

requirements.
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

J t.t.llollu|.ll"l"u"B"10" _0a.II0_.Iat IÈl_I_II_i_n"n_IH"H_I;_nn_"I"in"_on_n_t_H_"_on_n"_|_o_|_uino_o_oo .0 .alI_nlOO_aO .O He H010OlU H olooll.lonlonlollollol|o H o H o .oloolo_

(July 1994) RITSI: Toxicity testing was completed at NIST. The negotiations for toxicity and abatement testing

at Brunel are continuing. A manuscript of wind effects on flame spread is being prepared (joint theoretical and

experimental). TIFS-3D: The project obtained 2 LeRC civil servants to work on preliminary breadboard flow and

laser heater systems.

(August 1994) Theoretical study: A paper "Effects of Ignition and Wind on the Transition to Flame Spread in a

Microgravity Environment" by K.B. McGratton, T. Kashiwagi, H.R. Baum, and S.L. Olson is completed and it is

trader internal review prior to submission to Combustion and Flame. RITSI: More smolder-promoted papers were

made and sent to NASA LeRC for Learjet testing, normal gravity ignition testing, and CO toxicity testing at

Brunel University as part of the flight hardware verification testing. TIFS-3D: The project team met to discuss

design options.

(September 1994) Theoretical study: The internal review of the above paper has been completed after some

modifications corresponding to comments by the reviewers. An extended abstract based on the paper has been

written and submitted for presentation in the Eastern States Combustion Institute Meeting. RITSI: DC-9 Aircraft

tests were conducted where both plain and smolder-promoted paper samples were successfully ignited in low gravity.

The PI attended the First Meeting of NASA/NEDO Microgravity Combustion Coordinating Group for possible

microgravity experiments using the Japanese 10 seconds drop tower. Agreement was reached that this was a fruitt'ul

endeavor, and a formal brief proposal will be submitted to the MCCG for formal approval of this venture. The PI

"also reviewed the flight hardware design progress and the engineering hardware test results. TIFS-3D: We had an

informal meeting at NASA Lewis Research Center for discussing possible experimental parameters and diagnostic

measurements. We also discussed an outline of SRD for this experiment. A CO2 laser, a candidate radiant heater,

was successfully used to ignite paper with no soot spot or gas-phase hot wire pilot

STUDENTSFUNDEDUNDER RESEARCH: TASK INITIATION: 4/91 EXPIRATION: 12/97

PROJECT IDENTIFICATION: 962-22-05-35

RESPONSIBLECENTER: LeRC

___________!_on__o___!__oooIloo_o__o__o__o__o__o_______o__o|______o___________||__o_____ ___o|__|_o|__!_____o!oo_oo__oo___________!__!_o!_o____!_______o|log!on__o_o___!__o___________o__||_oIloo_o__o_log_______oIloo_oIlo___!_o____o___o__oo_______

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Sooting Turbulent let Diffusion Flames

PRINCIPALINVESTIGATOR:Prof. Jerry C. Ku Wayne State University

CO-INVESTIGATORS:

P.S. Greenberg NASA Lewis Research Center CLeRC)

TASK OBJECTIVE:

The objectives of this study are to model soot formation and radiation for turbulent jet diffusion flames and to

determine the modeling coefficients from measured data under both normal and reduced-gravity conditions.

TASK DESCRIPTION:

In regard to experimental measuremenLs, thermophoretic parucle sampling and electron microscopy are used for soot

particle size and aggregate morphology analysis. Laser light absorption imaging provides for the determination of

soot-volume tractions, and emission imaging and thermocouple measurements will be used for soot thermometry.

Laser Doppler Velocimetry may possibly be employed to measure velocities and turbulence intensities, but is

beyond the stated deliverables of this effort.

In the area of modeling, Favre-averaged boundary, layer equations with a k-e-g turbulence model and the conserved

scalar approach with an assumed pdf (probability density function) are used to predict flow field and gaseous species

mole traction profiles, respectively. Transport of soot particles is described by equations for volume traction and

number density using rate equation models. The energy equation is included to provide coupling between flame

structure and radiation analyses. The radiative flux is solved from the radiative transfer equation (RTE).

TASK SIGNIFICANCE:

Microgravity combustion is not only relevant to fire safety on-board a spacecraft but also provides a unique

condition for better understanding of fundamentals of this common type of combustion.

PROGRESSDURING FY 1994:

The YIX method was applied to solve radiative heat transfer in a finite cylindrical enclosure with a

nonhomogeneous, nongray, emitting, and absorbing soot/CO2 mixture. Numerical results were obtmned for

radiative heat transfer within a turbulent ethylene jet diffusion flame from precalculated flame temperature, soot

volume fraction, and CO2 concentration maps. Soot only, CO2 only, and combined cases were examined over the

spectral range of 1-20 microns. Soot absorption coefficient spectra were calculated from soot volume traction and

refractive indices according to the Drude-Lorentz dispersion model based on the three frequently cited dispersion

parameter sees. Results from these three dispersion parameter sets show that the difference in maximum flux is

51%. Thus, current uncertainties about soot spectral refractive indices are the main limitation on accurate estunates

of the radiation heat transfer from sooting combustion systems. The exponential-wide-band model is used to

calculate the CO2 absorption coefficient spectrum. Overall, the contribution of soot radiation is only two to three

times that of CO2. Consequently, both soot and CO2 contributions are significant, and must be accounted for. For

CO2 gas, only contributions around absorption bands at 2.7 and 4.3 microns are significant. It seems that spectral

contributions from the range above 5 microns may be neglected without any significant loss of accuracy in

evaluating total radiation properties. This work was submitted to the ASME Journal of Heat Transfer. In addition,

an improved method for handling the discontinuity between the velocity of fuel and co-flow has been implemented.

The agreement between m_xtel prediction and ProL Santoro's co-flow soot volume fraction data (already in the

literature) is very good now.

The fabrication of a coaxial, piloted burner tor turbulent gas jet diffusion flame studies has been completed.

Extremely small tubing diameters (n 0.75 nun inner diameter for the inner jet) were employed to obtain large

II-291
Reynolds numbers while retaining a reasonable overall flame height compatible with the dimensions of the

combustion chamber on the present 2.2 second laser rig. The major challenge was to provide a stable, coaxial

arrangement of the inner jet and pilot nozzles. This was accomplished by the staff of the LeRC instrumentation

shop, who employed an arrangement of laser-welded thin wire spacers to accurately control the relative position of

the inner and outer tubes. After welding the spacers in place, the thin wires were then ground to the appropriate

diameter to fit accurately into the pilot tube. The spacers also serve as flow straighteners for the pilot flow. Initial

tests indicate that adequate symmetry has indeed been achieved.

A series of drops were conducted in the NASA LeRC 2.2 -Second facility to obtain the soot volume traction in

reduced gravity laminar jet diffusion flames. Tests indicated a reduction in local volume traction for 1.5 rnm jets

using ethylene as a fuel at flow rates between 1.0 and 3.0 cc/sec. This resulted in volume traction signals (obtained

via light extinction measurements) with poor SNR's. Larger diameter burners were fabricated to provide longer

optical path lengths, thus increasing signa] strengths. Limitations on flow rate due to the capacity of the rig and

the resulting flame lengths proved to be disadvantageous because stable flames could not be achieved in the avai "lable

test time. Apparently Reynolds number considerations separate two different regimes wherein these flames are

either diffusion or momentum dominated. The former evolve too slowly to be studied in the 2.2 second facility; the

latter produce insufficient volume fractions for tractable flow rates and flame heights. Switching to acetylene as the

fuel increased the soot production to the level wherein reasonable SNR's could be obtained. Some issues relating to

the stability of these flames as a function of burner diameter and flow rate under reduced gravity conditions remain,

and are presently being pursued. The hardware has been performing consistently well, as has the facility's newly

refurbished air-bag deceleration system.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 3/91 EXPIRATION: 12/94

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-36

MS Students: 1 RESPONSIBLECENTER: LeRC

PhD Students: 2

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Hsu, P.F. and Ku, J.C. Radiative heat transfer in finite cylindrical enclosures with nonhomogeneous participating media.

to appear in AIAA J. of Thermophysics and Heat Transfer, (1994).
Soot and Radiation lvh>asurements in Microgravity Turbulent let Diffitsion Flames

PRINCIPALiNVESTIGATOR: Prof. Jerry C. Ku Wayne Suite University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TaSK OBJECTIVE:

The objectives of this studv are to determine modeling coetlicienk_ from measurements of soot morphology and

radiation in both normal and reduced-gravity turbulent gas.jet diffusion flames, and to lurther refine models fi_r soot

formation and spectr:dly dependent radiation properties.

TASK DESCRIPTION:

In the area of experimental measurements, thermophoretic particle sampling and subsequent transmission electron

microscopy analvsis are used tbr soot particle size and analysis of aggregate morphology. Laser light absorption

imaging provides for the determination of soot volume fractions. Emission imaging using isolated bandpass tilters

will be used to measure spectrally dependent soot radiation properties and possibly temperature. Rapid insertion of

fine-wire thermocouples will "also be used for the determination of temperature.

In the area of modeling, Favre-averaged boundary layer equations with a k-e-g turbulence model and conserved scalar

approach with an assumed probability density functions (pd/) are used to predict flow field and gaseous species mole

fraction profiles, respectively. The soot formation model has been modified and tested to predict soot volume

fraction and number density. The energy equation is included to provide a full coupling between flame structure

and radiation analysis. A third-order spherical harmonics approximation and the YIX method have been applied to

solve the radiative transfer equation. In the proposed study, soot formation mid radiation models will be improved,

_md methods lot efficient spectral integrations and iteration between the solutions for the flame structure and the

radiative transfer equation will be sought.

TASK SIGNIFICANCE:

Microgravity Combustion is not only relevant to fire safety on board a spacecraIt, but also provides a unique

condition for a better understanding of combustion fun "damentals of this common type of combustion.

PRO(3RESSDURINGFY 1994:

There is no progress to report at this time as the project has not started yet.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/95 EXPIRATION: 12/97

PROJECT IDENTIFICATION: 962-22-00

RESPONSIBLECENTER: LeRC

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IL MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

_qtudies of Flame Structure in Microgravtty

PRINCIPALINVESTIGATOR:Prof. Chung K. Law Princeton University

Co-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objectives of this work are to understand and quantity the structure, stabilization mechanisms, soot tormation

in, and extinction of one-dimensional premixed and nonpremixed laminar flames.

TASK DESCRIPTION:

This program comprises two main elements:

1. A numerical simulation of one-dimensional laminar flames is to be developed that, in addition to including the

usual fluid mechanical and heat transfer mechanisms, will include detailed chemical kinetic mechanisms for

comparison with the unique experimental results.

2. A drop-tower text apparatus is to be used to observe premixed laminar flames stabilized about cylindrical and

spherical porous burners to distinguish heat loss and flow divergence influences on flame stabilization and

flamefront stability.

TASK SIGNIFICANCE:

The one-dimensional adiabactic laminar unstretched premixed flame is a fundamental precept of combustion science,

but cannot be stabilized in normal gravity because of the straining or asymmetrical influences of gravitationally

induced buoyant convection. In microgravity experiments, this program demonstrates this combustion paradigm

and provides a capability for probing the structure, chemistry, soot dynamics, and flame propagation speed of these

fundamental flames.

PROGRESSDURING FY 1994:

This task was renewed in Fiscal Year 1994 with the award of an extended ground-based program entitled, "Studies of

Flame Structure in Microgravity," under NRA-93-OLMSA-1, "Microgravity Combustion Science: Research and

Flight Experiment Opportunities."

Progress on these two tasks are unseparable one from the other since the latter award is a simple continuation of the

former, and together consist of:

1. A series of tests were completed providing observations of cylindrical, premixed flames in microgravity. These

tests provided the ftrst observations of flames stabilized near a burner by virtue of the flow divergence only and not

by beat losses to the burner surface, as observed in normal gravity flame holding devices. This experimental work

has provided a new method for evaluating the adiabatic flame speed for premixed flames, a fundamental property of

fuels.

2. The lbrmulation of an asymptotic theory of spinning premixed flames is completed. This work extends the

previous diffusion flame analysis by Matalon (of a spinning fuel droplet undergoing diffusional burning in an

oxidizing environment) to the premixed flame situation, wherein a mixture of fuel and oxidizer is ejected from a

spherical source and subsequently burns as a premixed flame. This work is perlbrmed in anticipation of future

experiments involving spinning premixed flames which are subjected to differing body forces and strain rates over

the flame surface.

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11-294
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

3. The theory tot spinning spherical flames was investigated, including tour cases that span: premixed and

unpremixed fuels and fuels that require heat for vaporization la_ in droplet combustion or monopropellant spheres)

or those that do not (porous burner for gaseous fuels). This theory provides a basis for evaluating body force effects

and/lame stretch simultaneously. Preliminary results indicate a Lewis number dependence for the premixed case in

which the flame flattens at the pole or at the equator: and a demonstration of extinction for unity Lewis number

diffusion flames.

4. Experimentally, a new spherical burner has been developed using sintered metal, with flow incoming/tom both

polar positions. Observed flame fronts in normal gravity are not smooth, which may be caused by nonuniform

flow or by intrinsic flamefront instabilities.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 5/90 EXPIRATION: 11/94

PROJECT IDENTIFICATION: 962-22-05-37

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Eng, J.A., Law, CK. and Zhu. D.L. "Stabilization mechanisms and burning rates of cylindrical burner/lames."

AIAA-94-0571. presented at the 31st AIAA Aerospace Sciences Meeting. Reno, January 1994.

Eng, J.A, Law, C.K. and Zhu, D.L. "On burner-stabilized cylindrical premixed flames in microgravity." Twenty-Fifth

symposium (international) on Combustion. the Combustion Institute, presented, to appear, 1994.

11-295
Stn_cture and Dynamics of Diffusion Flames in Microgravity

PRINCIPALINVESTIGATOR: Prof. Moshe Matalon Northwestern University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objectives of the work are to gain insight into ditIusion flames by studying simple combustion systems. The

emphasis of the work will be to understand the structure and dynamics of stationary spherical flames, and the

coupled processes occurring in the liquid and gas phases associated with the burning of liquid fuels.

For gaseous flames, the Principal Investigator will investigate the processes that lead to extinction of these flames

either by the process of blowoff or by radiative losses. He will also examine the nature of the interactions between

two diffusion flames, the mechanisms leading to the generation of flame ti'ont instabilities, the formation of cellular

flames and the effect of resid 'ual gravitational acceleration on microgravity diffusion flames.

For liquid fuel burning, the Principal Investigator will examine the possible generation of instabilities that are

intrinsic to the vaporization process and identify the importance of thermocapillary motion on the overall burning

process.

TASK DESCRIPTION:

The program is entirely theoretical in nature. The Principal Investigator will work closely with related

experimental investigations in the microgravity combustion science program to identify problems of specific

interest.

The porous sphere will be the model problem tor gaseous diffusion flames. Astan "dard formulation of the

conservation equations in spherical coordinates forms the base case. The model will then be extended to incorporate

finite rate kinetics through activation energy asymptotics, enabling details of the flame structure to be elicited. The

model can then be extended to include a standard form of a radiative loss to determine the extinction limits, blowoff

and radiative, of the combustion system. Finally, the model will be extended to determine the effects of interaction

by modeling two spherical diftusion flames in close proximity to each other employing hi-spherical coordinates in

the approach outlined above.

As a next step the core model will be extended to incorporate stability theory and determine the conditions for the

onset of flame-front instabilities similar to those that have been observed experimentally. Similarly, the effect of a

low-magnitude, time-varying body, force (g-jitter) on the flame will be examined, by casting the disturbance as a

sinusoidal term in the governing equations.

The ideas developed above will then be extended to liquid fuels. The major change to the model will be the

incorporation of the liquid phase, the conservation equations for the liquid phase, and the coupling of the gas and

liquid phases. A major addition will be the incorporation of thermocapillary motion in the liquid phase equations.

TASK SIGNIFICANCE:

The proposed research will lead to a greater understanding of diffusion flames in general. By working closely with

experimental studies in the microgravity science program, the investigator will be able to give a theoretical

loundation to many experimental observations of diffusion flames in microgravity.
PROGRESSDURINGFY1994:

Currently, the participants in this program are Prof. M. Matalon (the PI) and two Ph.D. students. The work which

has been initiated is associated with 1) flame instability in pool burning, and 2) diffusional-thermal instabilities in

diffusion flames. For the first problem, a simple one-dimensional model has been developed describing the

evaporation and subsequent burning from a flat bed of a liquid fuel. The evolution of small disturbances is being

examined in order to identify possible instabilities. Expertments show that while one possible mode of burning is a

pool burning, in some circumstances a traveling front along the fuel bed may occur. The goal of the theoretical

investigation is to explain these observations. The analysis of the second problem requires a complete

understanding of the structure of a corrugated (three-dimensional) diffusion flame with arbitrary Lewis numbers (not

necessarily = 1). Previous work, notably that of Linan, has been restricted to one-dimensional flame fronts and to

unity Lewis numbers. It should be mentioned that while diffusion'd-thermal effects are reasonably well understood

for premixed flames, they are not well understood for diffusion flames. We have thus extended Linan's analysis and

gave a description for the structure of a diffusion flame of arbitrary 3D shape. Preliminary results indicate that in

the absence of fuel or oxidant leakage through the reaction zone, the diffusion flame is absolutely stable.

Instabilities are possible when leakage is present for a special range of the fuel and oxidant Lewis numbers and for a

Damkohler numbers that is near the critic'a] value corresponding to extincuon. We are currently mapping the region

of instabilities in terms of these parameters.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 5/98

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-47

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 2

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II-297
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Sdence

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Filtration Combustion for Microgravity Applications: (1) Smoldering, (2) Combustion Synthesis of

Advanced Materials

PRINCIPAL INVESTIGATOR: Prof. Bernard J. Matkowsky Northwestern University

CO-INVESTIGATORS:

A.Bayliss

V.A. Volpert

Northwestern University

Northwestern University

TASK OBJECTIVE:

The objective is to investigate combustion in porous media with applications to (1) smoldering and (2) combustion

synthesis of advanced materials, also referred to as self-propagating high-temperature synthesis (SHS).

TASK DESCRIPTION:

1. Proposing/developing theoretical models describing the fundamental mechanisms for the phenomena under

consideration, (2) perfomung complementary analytical and numerical work on the proposed models and

mechanisms, (3) comparing the results of these analyses to experiments.

TASK SIGNIFICANCE:

Both smoldering and combustion synthesis of advanced materials (SHS) contribute to fun "damental science, and also

represent important applications tbr microgravity combustion science; in smoldering to fire safety in both normal

and microgravity, and in SHS to the determination of optimal synthesis conditions in both normal and microgravity

environments. Combustion synthesis appears to compete favorably with conventional technology, by achieving

shorter synthesis times, and at lower cost, by employing the internal energy of the combustion reactions rather than

the costly external energy of a furnace, employed in conventional technology.

PROGRESSDURING FY 1994:

A paper entitled "Combustion of Porous Samples with Melting and Flow of Reactants," by A. Aldushin, B.

Matkowsky, K. Shkadinsky, G. Shkadinskaya, and V. Volpert is accepted for publication by Combustion Science

and Technology. The abstract of the paper reads: "We formulate and analyze a model describing the combustion of

porous condensed materials in which a reactant melts and spreads through the pores of the sample. Thus there is

liquid motion relative to the porous solid matrix. Our model describes the cases when the melt either fills all the

pores or spreads through only some of them. In each case the melt occupies a prescribed volume traction of the

mixture. We employ both analytical and numerical methods to find uniformly propagating combustion waves, to

analyze their stability and to determine behavior in the instability region. The principal physical conclusion which

lollows from our analysis is that the flow of the melted component can result in nonuniform composition of the

product. Unlike models which do not take into account the relative motion of the components, this model exhibits

a dependence of the structure of the product on the mode of propagation of the combustion front. Thus, if the initial

mixture is uniform, models which do not allow for relative motion necessarily lead to uniform structure of the

product, while in the model employed here the structure can be nonuniform. We observe that the structure of

uniformly propagating combustion waves depends on whether the refractory or melting componeft is in excess in

the initial mixture. We determine how various parameters of the system atfeet stability and find a pulsating

instability of the uniformly propagating solutions. We also perform numerical simulations in order to (i) study the

dynamical behavior of the combustion wave in the instability region, (ii) obtain a description of the melt flow on

the scale of the entire sample rather than on the scale of the combustion wave, i.e. to study the evolution of the size

of the liquid melt layer which may occupy only a part of the product region. We show, in particular, that a

transition to relaxation oscillations may occur closer to the threshold of instability than in gasless solid fuel

combustion. Our numerical and analytical results are in qualitative agreement."

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II-298
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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A paper entitled "Propagation and Extinction of Forced Opposed Flow Smolder Waves," by A.C. Femandez-Pello,

B.J. Matkowsky, D.A. Schult, and V.A. Volpert is submitted to Combustion and Flame. The abstract of the paper

reads: "Smoldering is a slow combustion process in a porous medium in which heat is released by oxidation of the

solid. If the material is sufticiently porous to allow the oxidizer to easily filter through the pores, a smolder wave

can propagate through the interior of the solid. We consider samples closed to the surrounding environment except

at the ends, with gas tbrced into the sample through one of the ends. A smolder wave is initiated at the other end

and propagates in a direction opposite to the flow of the oxidizer. We employ large activation energy asymptotic

methods to find uniformly propagating, planar smolder wave solutions. We determine their propagation velocity,

burning temperature, final degree of fuel conversion, and extinction limits. We also determine spatial profiles of gas

flux, oxidizer concentration, temperature, and degree of conversion of the solid, including the burning temperature

and final degree of conversion."

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 5/98

PROJECT IDENTIFICATION: 962-22-05-55

RESPONSIBLE CENTER: LcRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

.Journals

Aldushin. A., Matkowsky. B,. Shkadinsky, K.. Shkadinskaya. G. and Volpert, V. Combustion of porous samples with

melting and flow of reactants, accepted by Combustion Science and Technology. (1994).

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II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

Combustion of PTFE: The Effect of Gravity on the Production of Ultrafine Particles Generation

PRINCIPALINVESTIGATOR: Prof. J. T. McKinnon Colorado School of Mines

CO-INVESTIGATORS:

P.W. Todd University of Colorado

TASK OBJECTIVE:

This project is a study of the fundamental chemical and physical mechanisms of the production of ultra fine

particles, and the nature of the particles themselves, generated by the thermal breakdown of polytetrafluoroethylene

(PTFE) wire insulation. PTFE is a material that normally resists ignition and the spread, but it can degrade when

stressed by thermal and electrical overloads to release ultra fine (10 to 100 rim) particles as aerosols or smoke.

TASK DESCRIPTION:

The expernnental study will be performed in three tasks, as/bllows:

1. Initial normal gravity tests, conducted at the Colorado School of Mines in a simplified apparatus, heat reference

pertluoroalkane compounds in a tube furnace to generate ultra fine particles. These preliminary tests determine the

effects of temperature and residence time on particle generation and develop the means tor particle capture and gas

analysis.

2. Subsequent normal gravity tests, also conducted at the Colorado School of Mines in a closed chamber apparatus,

heat copper wires coated with PFFE. These advanced tests enable the detailed determination of particle sizes and

concentrations by nonperturbing light scattering measurements and the collection of particles by thermophoretic

sampling.

3. Subsequent microgravity tests, conducted by the investigators in the NASA Lewis Research Center drop tower

and airplane facilities, are essential for an understanding of the effect of the low convection environment on the

production of ultra fine particles and their possible dispersion and agglomeration, as a direct representation of

potential hazard situations in spacecraft.

The accompanying analytical study seeks to develop a comprehensive predictive model to predict ultra fine particle

production given inputs of heating rate, polymer quantity, degree of forced convection, and other factors. This

analysis is based on elementary reaction rates from established databases, the investigator's studies on soot

formation, and the interpretations of the results of the experimental tests.

TASK SIGNIFICANCE:

This study will examine the phenomenon of ultra-tine particle generation by the thermal degradation of a class of

spacecraft wire insulation. The results contribute to the knowledge of the physical and chemical mechanisms of

this process and offer practical applications in the reduction of health hazards in spacecraft and in the early warning

detection of tire incidents by atmospheric smoke sampling.

PROGRESSDURING FY 1994:

This project began on June 27, 1994 with the award of NASA Grant NAG 3-1628. The initial task is to design the

procedures of norm'd-gravity tests to determine the effects of temperature and resident time on the effluents produced

by a pyrolyzing polymer and to develop a means of effluent gas analysis and particle capture. The original plan was

to investigate the degradation of reference monomenc compounds, perfluoroalkanes, in a simple tube furnace.

Instead, the studies initiated with investigation of the thermal reactions of the target polymer,

polytetratluoroethylene (PTFE), since there is an immediate application for detailed analyses of the products of this

11-300
material. Concurrent life-science studies at the University of Rochester Medical School, supported by a NASA

Center for Research and Testing, shows that toxic solid and gaseous products are generated by pyrolytic reactions of

P'ITE at temperatures of 410 C and above. Gaseous products evolved in the tube-furnace tests will be separated and

identified by gas chromatography and mass spectroscopy. Ultrafine-particle products will be collected on a simple

filter plate, with morphologic',d- and chemical-analysis methods to be determined.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 5/94 EXPIRATION: 4/98

PROJECT IDENTIFICATION: 962-22-05-64

NASA CONTRACT NO.:NAG3-1628

RESPONSIBLECENTER: LeRC

II-301
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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Premixed Turbulent Flame Propagation in Microgravity

PRINCIPALINVESTIGATOR:Prof. Suresh Menon Georgia Institute of Technology

Co- INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The overall objective of this research is to characterize the behavior of turbulent premixed flames and to use the

experimental data to validate a novel computational method to simulate accurately the behavior of premixed flames.

In order to understand the behavior of turbulent flames, access to all the length scales (from the device size to the

Kolmogorov scale) in the flow field is required. A possible method to achieve this is to reduce the flow velocity.

However, in normal-gravity this is not possible due to gravitational acceleration and the turbulent stresses are

overwhelmed by buoyant stresses. Therefore, experiments in microgravity will be carried out that will allow the

study of low-speed turbulent flames without buoyancy effects.

TASK DESCRIPTION:

Premixed combustion of hydrogen-air mixtures will be studied in a Couette flow configuration which is essentially

a flow between two parallel plates moving opposite to each other. The turbulent flow field is characterized with the

flame speed being the primary variable of interest. Additional data on pressure rise and temperature is also measured.

TASK SIGNIFICANCE:

Improved understanding and modeling of practical turbulent flames will lead to increased efficiency and reduced

pollutant formation. Practical applications of technology to industrial combusters and high throughput engines

may be anticipated.

PROGRESSDURING FY 1994:

Preliminary, test plans and schedules were prepared and presented to NASA LeRC drop tower and diagnostics

personnel.

A detatled literature search was completed to determine what has been done related to premixed combustion and

turbulent flows in Couette-type configuration. Relevant papers were collected and reviewed. The review of the

literature clearly showed the following: (a) there has been no numerical and/or experimental work carried out/'or

turbulent combustion (both premixed and non-premixed) in Couette flow configuration, (b) there have been quite a

few experimental studies of plane-Couette flows, however, the configurations were quite different - - in most cases,

it consisted of only one wall moving and hence simulated a plane shear flow in a channel. These configurations

were quite large setups and not considered feasible for the present study. Only two cases were found (other than the

original report from Germany), which involved setups and testing procedure relevant for the present study. In

particular, one configuration appears quite promising to study Couette cold flows since it appears to be easily

constructed and will allow very long testing times. Cold flow testing will be the first experimental study since it

would allow us to resolve the various issues related to turbulence measurements in such flows. (c) there have been

numerous numerical studies of turbulent Couette flows; however, most of the studies were for the mean

(steady-state) flow calculations using Reynolds-Averaged methods with turbulent closure and no unsteady flows have

been studied. In summary, the review of available literature clearly indicates that there have been no studies of

premixed combustion in turbulent Couette flows, and it further indicates even cold (non-reacting) unsteady flows

have not been studied.

Based on the literature study, a numerical study of premixed combustion in a plane Couette Flow was initiated. The

configuration is similar to the one planned for the experimental study. Premixed flame propagation is modeled using

_u_*_t_t_t_tt_tt_tt_s_*_*_t_*t_tI_t_t_t_u_t_tt_t_*H_t_nn_n_i_t_t_1_u_tt_tttn_t_Itt_tutuo_t_tt_tu_t_tt_t_e_t_*_t_*_tf_*t_*tII_t_tn_u_t

11-302
the G-equation model. This approach ,allows the study of thin flames without requiring detailed kinetics modeling

and therefore, is computationally very. efficient. Unsteady turbulent flow is stmulated using the large-eddy

simulation methodology. The first phase involves simulations in two dimensions; however, we plan to move to

lull 3D within the iirunediate future. The 2D code is `already operational.

A test problem was identified for the numerical code validation. This problem consisted of only one moving wall;

however, detailed experimental data had been obtained for this case and therefore, the numerical predictions can be

validated using the experimental data. Preliminary calculations of laminar Couette flows were carried out and an

excellent agreement with the classical results was obtained. Currently, simulations of the turbulent flow are

underway by using a turbulent inflow that consists of a mean flow and isotropic turbulence. The above noted

studies are being carried out using a 2D LES code. However, the eventual goal is to simulate full 3D flows;

therefore, a 3D version of this code is also being set up and is planned to repeat the 2D validation studies with the

3D code.

On the expertmental side, the design issues for the cold flow experiments are being addressed. The exact dtmensions

have not yet been finalized, but the configuration under current consideration is similar to the setup used by

Tillmark and Alfreck_son in Sweden. The main differences are (a) the present study will employ gases (e.g., air and

helium) and therefore, leakage is a serious issue, (b) the configuration will be much smaller overall in order to be

applicable to the reacting Couette/low configuration, (c) the range of spacing between the two belts and the range

of Reynolds number will be different and (d) it is planned to carry out detailed turbulence measurements and flow

visualization of a no-heat release "flame" front (which will be generated by introducing in the channel center a new

species that can be tracked - - currently acetone and byacetyl dye are being looked at).

STUDENTSFUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 5/94 EXPIRATION: 5/98

PROJECT IDENTIFICATION: 962-22-05-48

RESPONSIBLECENTER: LeRC

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11-303
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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A Fundamental Study of the Combustion Syntheses of Ceramic-Metal Composite Materials Under

Microy, ravity Conditions

PRINCIPAL INVESTIGATOR:Prof. John J. Moore Colorado School of Mines

GO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The obiective is to obtain an improved understanding of the effect of gravity on the combustion synthesis of

ceramic matrix-metal infiltrated composites and to develop new and improved-property materials.

TASK DESCRIPTION:

Combustion synthesis reactions are conducted under normal gravity (various orientations of samples with respect to

gravity) and in microgravity to generate either porous or dense ceramic matrices in the presence of varying amounts

of excess A1203 (diluent) and/or excess "aluminum, which will be available to fill residual pores by capillary action.

The effects of gas generation during reactions on the porous matrix tormation are studied under different levels of

gravity. The dense composite materials are produced using a one step, low cost, simultaneous

combustion-consolidated process. The microstructure and properties of both dense and porous product composite

materials arc "also characterized.

TASK SIGNIFICANCE:

An improved understanding of the role of gravity on the combustion synthesis of ceramic-ceramic and ceramic

matrix-metal composite materials "allows for new approaches lor the development of specified micro-structures,

thereby resulting in improved material properties. One can "also explore ways to develop brand new materials by

microgravity processing (e.g. high surface area expanded or toamed ceramics, and fully dense interpenetrating phase

composites). The expected benefits of such inexpensive, light, strong, and either highly porous or dense composite

materials range from construction-support systems to liquid-metal, filtering-systems applications.

PROGRESSDURING FY 1994:

The B4C/AI203 system using the reaction:

2B20 _ + C + (4+x)Al + yAl:O 3 -> B4C + (2+y)Al:O 3 + xAl

is being persued based on the observation that this system showed expansions of approximately 150% under 2-g,

and over 400% under 0-g conditions (Lear Jet), as opposed to 300% under n-g, after the combustion synthesis

process. A new student will concentrate her efforts on the more accurate control of the combustion temperature to

avoid melting AhO3. If successful, this would provide an increased surface area in the expanded ceramic composite.

Two modes of combustion are being studied: 1) simultaneous, where the mixture is ignited by heating the whole

pellet at once, and 2) propagating, where the ignition is at one end of the pellet. Depending on the v',due of y and

combustion mode, the reactions are observed to be quenching, unstable, or stable, and the product has different pore

sizes, distribution and expansion.

By using the 'simultaneous' combustion mode for cylindrical pellets they observed radial expansions of about 13%

in addition to an axial expansion of about 15%, i.e. near three-dimensional uniform expansion. The scanning

electron microscopy analysis shows that the samples contained a marked amount of submicron diameter whiskers.

11-304
Upon an informal review of the grant, the Space Experiments Division at LeRC came up with a number of

recommendations. Prof. Moore agreed that a student should re-analyze the x-ray radiography tapes from previous

NASA Lear Jet flights for a better verification of reaction speed and quantification of pore formation and progression

in samples of the B4C/AI203 system. X-ray and scanning electron microscopy (SEM) work is providing evidence

/or the speculation that reactions are occurring ahead of the combustion front.

Samples for the B4C/AI203 system with 20 wt% excess AI are still planned to be flown on the Lear Jet with

operation by LeRC personnel for about eight trajectories. After the 10 wt% excess A1203 (diluent) samples, the

student reacted some 5 wt% and no excess AI203 samples in argon gas (inert aunosphere). Their SEM images also

show the formation of shells within the sample. She will determine the interior structure and composition of the

shells by using electron back-scatter imaging. She also plans to measure the surface area. A trend of continuous

reduction in combustion temperature with increasing diluent is being observed.

The vacuum pump is in place to complete reactions utilizing 25 wt% AI:O3 as a diluent. The goal is to decrease

the combustion temperature of the reaction system below the melting point of AI._O_ so that the reacted samples

exhibit a higher surface area/weight ratio.

The other graduate student is processing the TiC/AI_O3/AI system using the reaction:

3TiO_ + 3C + (4+x)Ai + yAi203 -> 3TiC + (2+y)AI203 + xAI

under normal gravity conditions using a hot press. He reports that the same level of uniformity of the metal

network readily obtained under micro-g conditions would require pressures of 4000psi under normal-g conditions.

He will also develop physical and computer models to predict these phenomena. He is studying the effect of green

powder particle size on the kinetics, stability, and product microstructure of the TiC/AI2OJAI system. Larger

particles decrease the stability of the reaction. He has determined that metallic AI bonding between particles in

products when excess A1 is used is the main reason for the enhancement of strength and toughness. While fine

particles result in more homogeneous pores in the final product, they produce no whiskers. On the other hand,

coarse particles can produce whiskers when excess A1 (x>2) is used.

The student then has achieved fracture toughness values twice as much as that of pure AI203 using various values of

the stoichiometry (x and y), and consolidation pressure. The samples with higher fracture toughnesses exhibit

smaller grain sizes and more homogeneous morphologies than their lower fracture toughness counterparts. Both

A120_ and AI are used in excess to control the combustion temperatures and, thereby, the microstructures and

mechanical properties.

Finally, he has successfully defended his PhD Thesis in June 1994 and will continue working on the same system

as a post-doe for six more months.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 8/91 EXPIRATION: 12/94

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-22-05-38

MS Students: 2 MS Degrees: 1 RESPONSIBLECENTER: LeRC

PhD Students: l PhD Degrees: 1

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11-305
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Feng, H,J, and Moore. J.J. Combustion synthesis of high performance ceramic-metal composits. High Performance

Metal and Ceramic Matrix Composites. TMS. ed. K. Upadhya. 157-174 (1994).

Feng, H.J. and Moore, J.J. In-situ combustion synthesis of dense ceramic and ceramic-metal interpenetrating phase

composites, accepted, Met. Met, Trans. (1994).

Feng, H.J. and Moore, J.J.. The design of an affordable one-step process for the production of a functionally-graded

material (FGM). accepted, J. Mat. Synth. Proc., (1994).

Feng, H.J. and Moore, J.J. Combustion synthesis of dense ceramic-metal composites, accepted, Ceramic Matrix

Composites. Ceramics Transactions, (1994).

Feng, H.J,, Hunter. KR., and Moore. J.J. Combustion synthesis of ceramic and metal-matrix composites. J. Mat. Synth.

Proc. 2, 71-86 (1994).

Hunter, K.R. and Moore, J.J. The effect of gravity of the combustion synthesis processing of advanced materials. 6th Int.

Syrup. Experimental Methods for Microgravity Materials Science, TMS. eds. R.A. Schiffman, F.B. Andrews, 125-131

(1994).

Hunter. K.R. and Moore. J.J. Effect of gravity on the combustion synthesis of ceramics and ceramic-metal composites.

accepted. J. Mat. Synth. Proc.. (1994).

Moore, J.J. An examination of the thermochemistry of combustion synthesis reactions. Processing and Fabrication of

Advanced Materials III, TMS, eds. V.A, Ravi, T.S. Strivatsan, J.J. Moore. 817-831 (1994).

Moore, J.J. Self propagating reactive synthesis of advanced materials. Proc. of Powder Matallurgy World Congress,

Paris, June 6-9, 1994 (European Powder Metal Association), (1994).

Moore. J.J. and Feng, H.J. Combustion synthessis of advanced materials: Part 1, reaction parameters, accepted, Progress

in Materials Science, (1994).

Moore. J.J. and Feng, H.J. Combustion synthesis of advanced materials: Part 11, classification, applications and

modeling, accepted, Progress in Materials Science, (1994).

Moore. J.J., Readey, D.W., Feng, H.J. and Monroe, K. Exothermic reaction (combustion) synthesis of advanced ceramic,

intermetallic and composite materials, accepted, J. of Metals. (1994).

Presentations

Fcng, H.J. and Moore. J.J. "Combustion synthesis of dense ceramic-metal composits." Ann, Mtg, _)t Am. Ccr. Soc..

Indianapolis, IN. April, 1994.

Feng, H.J. and Moore, J.J. "Combustion synthesis of high performance ceramic-metal composits." High Performance

Metal and Ceramic Matrix Composites. TMS. Warrendale, PA, 1994.

Feng, H.J.. K.R. Hunter and J.J. Moore "The application of combustion synthesis in the production of titanium-based

ceramic and ceramic-metal composites." Eng. Found. Conf. on High Temp. Strut. Mater., Hawaii, 1993.

Hunter. K.R. and Moore, J.J. "The e/fect of gravity of the combustion synthesis processing of advanced matcria/s." 6th

Int. Symp. Experimental Methods for Microgravity Materials Science, TMS, Warrandale. PA. 1994.

Hunter, KR.. J.J. Moore "The effect of gravity on the in-situ combustion synthesis of ceramic-metal composites.."

AIAA 94-0568, presented at the AIAA 32nd Aerospace Sciences Meeting at Reno, NV. Jan. 10-13. 1994.

Moore, J.J. "Self proagating reactive synthesis of advanced materials." Keynote Lecture. 1994 Powder Matallurgy World

Congress, Paris. June 6-9. 1994,

Moore, J.J. "An examination of the thermochemistry of combustion synthesis reactions." Processing and Fabrication of

Advanced Materials 11I, TMS, Warrend',de, PA, 1994.

11-306
Flow and Ambient Atomosphere Effects on Flame Spread at Microgravtty

PRINCIPALINVESTIGATOR:Prof. Paul D. Ronney University of Southern California

CO-INVESTIGATORS:

Sandra Olson NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

This program is a three-year experimental and theoretical study of the effects of ambient atmosphere on the

properties of flame spread over thin and thick solid fuel beds. In particular the effect of the type of inert gas, which

affects the Lewis numbers of fuel and oxidant, and the effect of the addition of sub-flammability-limit

concentrations of gaseous fuels to the oxidizing atmosphere will be studied. The effect of convection will be

studied through one--g and mg experiments with and without a forced flow. Moreover, the influence of thermal

radiation, whose effect is known to be markedly different depending on the convection level, will be addressed.

TASK DESCRIPTION:

The emphasis of this studv is on thermally Olin fuels because of the limited lag test tune available in ground-based

facilities, and preliminary scaling an',dyses suggest that thenn_dly thick fuels can be ex:unined as well when gaseous

fuel is added to the oxidizing atmosphere.

The experiments will be conducted in a combustion chamber in which a convective flow of a few cm/sec can be

imposed in the direction opposite the flame spread. The oxidizing atmosphere will be mixed by the parti',d pressure

method. For tests of Lewis number effects, inerts He, Ne, Ne, CO: and SF 6 will be used since they provide Lewis

numbers from about 0.3 to 1.4. CO and CH4 will be used for the gaseous fuels. Thin fuel samples will be ashless

filter paper and thick fuel samples will be PMMA. Fuel samples of varying thickness will be ignited by the heat

generated by a current passed through a coiled nichrome wire coated with nitrocellulose.

The primary diagnostics are video and an _m-a,,' of fine-wire thermocouples to measure the temperature

simultaneously at several locations. The video recorcts provide reformation on the spread rate and flame shape. The

thermocouples give an independent check of the spread rates and the existence (or lack thereol) of a separate flame

trent in the case of added gaseous fuel. The temperature daui may 'also be used to determine the heat t]ux from the

gas phase to the ltiel bed. which can be related to the spread rate.

TASK SIGNIFICANCE:

The understanding and control of accidental fires is a critical safety issue in both terrestri',d and space_-bome

environments. The proposed work would provide insight that could be used to assess the fire hazards _Lssociated

with non-standard atmospheres that might be employed in future manned spacecraft. Also, fires ill enclosures

produce a considerable amount of unburned vaporized fuel and patti',ally combusted gases such as CO. One-g

experiments have shown that the addition of combustible gases such as CO to the oxidizing atmosphere may

increase the flame spread rate subslarltially. This sludy could provide information to improve models of tire

development and spread in ench)sures at one-g and Jag.

The influence of weak forced convection is particularly important for studies of flame spread at lag because there is

very little buoyancy-reduced I]ow at lag. Experunents by Olson and collaborators shows that the presence of forced

convection currents ITor exzunple due to ventilation systems in manned spacecraft) can have a profound effect on the

spread rate and extincuon conditions. Consequently, the understanding of these effects is critical to understanding

how fires might start, spread, and be exduguished at lag conditions.

11-307
IL MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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PROGRESSDURINGFY 1994:

To improve the sensitivity of the video imaging system for the very weak near-extinction flames, a shearing

intefferometer has been designed and is being constructed tbr evaluation. The shearing intefferometer has no parts

that have critical alignment requirements, and thus may be especially suitable for drop tests. The interferometric

measurements may also be useful to supplement the thermocouple temperature measurements.

A graduate student is modifying our existing one--g flame spread apparatus for use in drop towers with regards to

fuel sample mounting, optical access, and data acquisition.

As a precursor to the experimental study, an analytical study has been initiated in conjunction with Dr. Mike

Delichatsios of Factory Mutual Research Corporation in Norwood, MA. The goal of the work is to extend Dr.

Delichatsios's previous (1986) exact solution of flame spread over a pyrolyzing fuel bed to consider the effects

Lewis number, finite-rate chemistry, and gaseous fuel addition on flame spread rate. A preliminary theory of Lewis

number effects on flame spread over thin fuel beds, including finite-rote chemistry, has been obtained and compared

with prior one-g data from Zhang et al (1992).

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 2

PhD Students: 0

TASK INITIATION: 5/94 EXPIRATION: 4/98

PROJECT IDENTIFICATION: 962-22-05-61

NASA CONTRACT NO.:NAG3-1611

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Delichatsios, M.A. and Ronney, P.D. "Horizontal and lateral flame spread on solids: closure and diffusional Lewis number

effects." Fall Technical Meeting, Combustion Institute, Eastern States Section, Clearwater Beach. FL, December 5-7,

1994.

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11-308
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

Combustion Research

PRINCIPAL INVESTIGATOR: Dr. Howard D. Ross NASA Lewis Research Center (LeRC)

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The task objective is to advance the understanding of fundamental combustion phenomena and/or processes that are

',dfected by the presence or absence of gravity.

TASK DESCRIPTION:

The research approach is to provide for lhnited precursor studies by external investigators and for the engineering

and l_abrication of hardware needed to conduct in-house research and assist in the research efforts conducted on-site at

LeRC in support of Code UG-sponsored Principal Investigators (PI's) and National Research Council (NRC)

graduate student researchers. Funds for facility overhead charges are provided through separate Research and

Technology Operations Plans (RTOP) resources,

SubtasLs are funded in part by this task,or are included for completeness at the request of NASA Headquarters.

TASK SIGNIFICANCE;

Significance varies with the various research efforts, and therefore, more focused, effort-specific, statements are

given below.

PROGRESSDURINGFY 1994:

Funds were disbursed to support service contractors to perform technical analysis and assistance for selected ground-based

microgravity combustion science research grants and cooperative agreements. In addition, a number of research activities

were conducted by onsite staff, including NRC post-doctorate fellows and Graduate Student Research Program fellows,

associated with both ground-based and flight projects. The objective, approach, significance, and progress for each of

these research activities are described below.

Combnstion Synthesis of Fuilerenes -.l. Brooker

Objective:

The objective of this research is to produce, collect, and quantify fullerenes synthesized during combustion under norm',d

gravity and microgravity and compare the results relative to: C60 and C70 composition. C60 and C70 percent of soot. and

C70/C60 molar ratio. In phase one. acetylene will be burned in a gas-jet premixed flame: in phase two. benzene will be

studied.

Description:

Flames will be used to generate fullerenes in a sub-atmospheric combustion chamber. Normal gravity tests will be

performed to determine conditions favorable for fullerene production and to define a suitable method of collection and

species separation/identification. Subsequent experiments will employ the 2.2 Second Drop Tower and possibly aircraft.

Significance:

The suggested potential applications for fullerenes include superconductors, lubricants, catalysts, high energy fuels.

polymers, and biomaterials. Some of the emerging applications that are currently under investigation include the growth

of diamond films on surfaces for protective coatings and electronic industries, their use as optical limiters to protect

sensors from intense radiation sources, incorporation of fullerenes into photoconducting polymers with applications in

light detection and electrostatic imaging, and the possible use of fullerene derivatives as drugs to combat AIDS by

interacting with the active site of HIV.

Progress:

A literature search on fullerene properties and methods of production began along with a study of combustion texts to

11-309
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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become familiar with the theory. Micr_}sofi Proiect will be used to identifying tasks, resources, and milestones and track

project success. In addition, a research c,mcept diagram was developed identifying hardware requirements and volume

constraints.

Design of the burner, vacuum system, collection system, and diagnostic pallet began. Various parts were identified for

procurement/fabrication and orders were submitted. With the LeRC Chemistry Laboratory, we are determining the

analytical equipment and procedures necessary to identify fullerenes and to separate them from the other combustion

products.

Investigation of Burning Droplets of Azeotropic Mixtures - Dr. R. Colantonio

Objective:

Non-ideal mixtures that exhibit a relative extremum in their vapor pressure and "volatility reversal" at a particular

composition (azeotropic pointl are classified as azeotropic mixtures. This investigation will observe the liquid droplet and

flame histories and location of the azeotropic point for a number of binary azeotropic mixtures.

Description:

Droplet burning of azeotropic mixtures will be pertormed at 1-g and at the NASA 2.2 second Drop Tower. A demonstrated

droplet deployment and ignition system will be used. The droplet deployment system consists of two deployment needles

that merge together via rotary motors. A fuel dispenser will form the droplet between the two needles tips. Once the droplet

is formed the rotary motors withdraws the needles. Two hot-wire hoops will be used to ignite the fuel droplet once the

neddles have been withdrawn and the droplet is suspended during reduced gravity.

Both a color CCD camera and a high-speed 16 mm camera will be used to observe the burning characteristics of the

azeotropic fuel mixtures.

Significance:

Many hazardous liquid wastes (e.g. aromatics, polyhalogenates, alcohol's and hydrocarbons) can form azeotropes. The

unique feature about the behavior of azeotropes is the modulating of relative volatilities of the components by suppressing

gasification of the lower or higher boiling point beyond a critical composition. This feature is very important in the

disposal/incineration of azeotropic mixtures and in the chemical distillation industry. Limited data exists on the burning

of azeotropic droplet mixtures. Both reduced gravity and normal gravity experiments on burning azeotropic droplet

mixtures will lead to fundamental understanding of the volatility reversal and burning characteristics.

Progress:

Experimental hardware was procured and is currently being assembled with testing tentatively scheduled for December

1994. Tetrachloroethene/propanol and ethanol/water mixtures are likely candidates for the first series of testing.

A Transient Model of Flame Spread Over Solid Fuel in Microgravity - Dr. P. Ferkul (NRC)

Objective:

The objective of this effort is to develop an unsteady model of flame spread over solids. Initially thin fuels will be

examined, but eventually flames spreading over thicker, more realistic fuels will be considered. (When the fuel has an

appreciable thickness, the flame does not typically reach a steady state.) The effect of ignition on the flame spread process

is sought. Also, the flammability boundary, as a function of oxygen percentage and flow velocity, is to be investigated.

The detailed dynamics of flame extinction can be examined with this model.

There are several other related objectives. The first is the development of a good algorithm to handle the interface between

the solid and gas phases at the fuel surface when the fuel gets appreciably thick. The changing geometry due to fuel

consumption complicates the specification of boundary conditions, The second is the potential treatment of turbulence

since some of these long flames may tend to become turbulent in the downstream region. The third is the identification of

those cases where a "quasi-steady" solid tormulation will be adequate, as opposed to those where the fully unsteady solid

phase equations are necessary.

Description:

An existing steady-state computer code will be modified. This original program is based on the SIMPLER algorithm which

is a general fluid flow solver. The full Navier-Stokes equations are used. together with conservation of energy and fuel and

oxygen species. A second-order finite-rate chemical reaction is assumed to model the combustion, Radiation from the fuel

surface serves as a heat loss mechanism, The Cray Y-MP at NASA LeRC will be used to compute, store, and process the

large amount of data which will be produced,

11-310
Significance:

The purpose of this effort is to both guide and predict related experimental work. Together with the experimental work, the

model will provide fundamental insight into flame spread at microgravity. The work has direct application to spacecralt

fire safety.

Progress:

The details of the flow around the fuel burnout point were examined. This region is important since it serves as the flame

stabilization point and will thus have implications on extinction. Several references of cold flow in the leading edge

region of a semi-infinite flat plate were examined. One reference suggested that using "parabolic coordinates" instead of

the primitive cartesian coordinates may better capture details at the leading edge.

Using this suggestion, the parabolic coordinate system has been defined. The coordinate transformation of the

Navier-Stokes equations from cartesian to parabolic was performed, using the vector form of the unsteady, compressible

Navier-Stokes equations. The equations for parabolic-cylindrical and parabolic-axisymmetric coordinates were derived.

Venting Extinguishment Experiment - J. Goldmeer (GSRP)

Objective:

The G.S.R.P. Venting Extinguishment Experiment is examining the extinction of a solid diffusion flame at low pressures

in reduced gravity. The experiments being conducted will yield data on the flammability of the fuel at various pressures,

oxygen concentrations, and flow velocities. This data will provide information regarding the effectiveness of the

depressurization process as a fire extinguishment technique in reduced gravity.

Description:

The Venting Extinguishment Experiment is examining the combustion and extinction behavior of a solid, horizontal,

PMMA cylinder in a low-speed flow in reduced gravity. The depressurization process is being examined in three phases.

The first portion involved 1-g testing to determine the appropriate test parameters. The second portion of the research

examined the effect of reduced gravity on the selected combustion configuration utilizing the NASA Lewis 2.2 Second Drop

Tower.1 The third phase of the research will examine the effects of flow and depressurization on the flame in 1-g and in

low-gravity. The low-g depressurization experiments will be conducted on board a NASA reduced gravity aircraft. (This

research is part of J. Goldmeer's doctoral program at Case Western Reserve University).

Significance:

Combustion of solids in low-speed forced flows at reduced gravity is relevant to fire safety in spacecraft. In an emergency a

compartment within a space vessel could be intentionally vented to space to extinguish a fire. However, the effect of the

induced flow on the fire in the low gravity and low pressure environment is unknown.

Progress:

A series of tests were conducted on board the KC-135. In the combustion tests the PMMA cylinders (2.5 cm in length, 1.9

cm in diameter) were ignited during the 2-g portion of the trajectory with flow in the chamber. A focus of the analysis has

been the centerline temperature of the samples,

Steady-state extinction tests (lg) were also conducted. In these tests a horizontal PMMA cylinder was ignited in a forced

flow and the pressure was slowly reduced until flame extinction occurred. During the experiment the velocity was kept

constant.

In these tests three different combustion modes were evident as the pressure was reduced. The first was a flame which

surrounds the cylinder completely. The second mode of combustion occurred when the chamber pressure was reduced to

approximately 0.1 atm. The flame at the lower stagnation point of the cylinder experienced blow-off, and the flame which

was still burning along the upper surface of the cylinder began to oscillate. (This behavior was previously seen in lg

oxygen depletion experiments,) The third mode occurred after the oscillations stopped. The flame slowly transitioned

into a wake flame. The flames along the upper surface extinguished at approximately 0.07 atm. this pressure seemed to be

independent of the flow velocity.

During all tests, the temperature at the center of the sample was measured by a thermocouple probe. There was a correlation

between the measured solid temperature at the center of the cylinder pressure at extinction. As the solid temperature

increased, the pressure required to extinguish the flame decreased,

A series of reduced gravity tests were conducted again on board the NASA Lewis Lear Jet. Forty-four trajectories were

accomplished in nine flights. The experiments examined the steady-state extinction with a constant forced flow in reduced

gravity. The chamber pressure and the temperature at the center of the solid were measured during these experiments.
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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Above a critical solid centerline temperature the flames did not extinguish in reduced gravity. Examining the trend in that

data indicated that the pressure required to obtain extinction decreased as this critical temperature increased. At

temperatures below this range, the flames extinguished during reduced gravity. This has implications for the possible use

_)t" venting (depressurizatioul as a method for extinguishing fires on board spacecraft.

tteat Release Effects on Shear-Layer Instabilities - Dr. U. Hegde

Progress'.

During FY 94. studies were conducted in primarily two areas:

(i) Heat release effects on shear-layer instabilities

The effects of unsteady heat addition on instabilities of parallel shear layers in the absence of gravity was analyzed. It was

shown that, in the linear regime, the influence of heat addition is felt only through the time-averaged velocity and

temperature fields, that is, the unsteady component of the heat addition plays no active role. The analysis which has

application to both premixed and diffusion flames was published in AIAA Journal.

(ii) Effects of unsteady heat transfer to a burning solid fuel

In collaboration with Dr. M. Vedha-Nayagam, analysis of the oscillatory behavior of opposed-jet diffusion flames was

extended to a stagnation point solid fuel diffusion flame. This is an area where microgravity environment may be of use in

studying the effects of turbulence on flames. The effects of velocity fluctuations in the oxidizer stream on oscillations in

the burning rate of the fuel and flame intensity were investigated. The analysis was carried out to second order to

investigate the time-averaged shift away from the undisturbed flame configuration. It was found, for cases considered, that

the velocity oscillations caused an increase in the flux of reactants into the flame. Results were presented at the Central

States Section Meeting in June.

Diffusion Flame Extinction Dynamics - V. Nayagam

Objective:

The obiective of this research is to investigate the extinction dynamics of diffusion flames at small, as well as large stretch

rates. The experimental portion of this study employs a rotating fuel-disk. The diffusion flame supported by the spinning

fuel disk is embedded in the induced 'Von Karman' boundary layer. This novel flow configuration enables one to control

the stretch rates precisely. The theoretical effort makes use of large activation energy asymptotics to examine the

extinction process. The attempt is to provide a unified of high stretch extinction (blow-off) and radiation heat loss

dominated low stretch extinction.

Significance:

A knowledge of conditions under which diffusion flames extinguish is of fundamental as well as practical importance.

Furthermore. the concept of laminar flamelets as an embedded structure that controls turbulent diffusion flames has

provided a new impetus to further understand laminar extinction conditions in a variety of flow configurations. In the

present study a rotating fuel disk induces a three dimensional boundary layer in which a laminar diffusion flame is

established. A range of chemical and fluid mechanical time scales over which extinction conditions occur are produced by

changing the environmental conditions (pressure and oxygen concentrations), fuel. and the spinning velocity of the fuel

disk. High speed filming of the burning process, and temperature measurements provide quantitative information

regarding the extinction dynamics.

Progress:

The large experimental apparatus used earlier for normal gravity studies has been redesigned and miniaturized to fit into the

standard drop-tower frames. The new design is currently being built. A theoretical model for the extinction process using

the activation energy asymptotic technique has been developed. The model predicts extinction at high stretch rates (high

RPM) as well as radiation heat loss induced low stretch extinction. The extinction condition is characterized by a critical

Damkohler number.

Stability of Laminar Premixed Gas Flames - Dr. H. Pearlman (NRC)

Objective:

The objective of this study is to develop a fundamental understanding of the inherent stability of premixed gas flames at

earth and micro-gravity.

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11-31 2
lI. MSADProgram Tasks -- Ground-based Research Discipline: Combustion Science

Description:

The research approach is to design and construct hardware used to study freely-propagating flames in tubes in both normal

and microgravity. This experimental configuration is chosen because it eliminates the additional complexities of heat

loss and hydrodynamic effects common to burner stabilized flames.

Significance:

Understanding the intrinsic stability of premixed gas flames is essential to our fundamental understanding of heat and mass

transport in the presence of chemical reaction. This work is applicable to our understanding of combustion phenomena as

well as to our knowledge of a broader class of chemical and biological systems known as reactive-diffusive systems, which

include such diverse phenomena as the patterns of spots on anmaals, the spread of infectious disease, the formation of

spiral galaxies, as well as the rhythmic beating of a human heart and the solitary voltage pulses which travel along nerve

fibers.

Progress:

One of the most fundamental problems in premixed gas combustion is the stability of a steadily-propagating, planar flame

in a quiescent environment in the absence of forced or natural convection (buoyancy). Its stability will depend on: (1) the

rate at which the heat liberated by the flame diffuses into the cold reactants versus the rate at which the stoichiometrically

scarce reactant, the rate-limiting component, diffuses into the flame (i.e.. the diffusive-thermal mechanism) and (2) the

ratio of the heat lost to the heat generated by the flame. The first of these two effects can be characterized by the Lewis

number (Le) of the mixture where the Le is defined as the ratio of the thermal diffusivity of the bulk mixture to the mass

diffusivity of the stoichiometrically scarce reactant in the bulk mixture.

Low-Le (cellular flame) instabilities have undergone extensive experimental and theoretical treatment during the past

century, yet, the high-Le instability has managed to evade experimentalists, until now, even though theoretical treatment

by Joulin and Clavin, Matkowsky and Olagunju, and Booty et. al. have strongly suggested that pulsating and/or traveling

wave instabilities arise in high Le number mixtures.

The first observations of these instabilities were made in the 2.2 second drop tower at NASA LeRC using a lean mixture of

butane and oxygen diluted with helium (Le_3.0)l,2. Based on these tests, we realized that the reason the instabilities have

not been observed earlier is because the oscillation frequency is on the order of 100 Hz (or higher); much too fast to be

detected by the human eye or at standard video framing rates.

Consequently, we use a high speed intensified video camera to visualize the flames. We observe two intrinsically unstable

modes of flame propagation: (1) a pure radial pulsation and (2) a combined radial pulsation and traveling wave instability.

These modes have been observed at lg and ug which suggests that the instabilities are not buoyantly-induced, but rather

inherent to the flame itself, caused by an imbalance between heat and mass transport in the presence of chemical reaction.

One of the most striking feattares of these high Le number instabilities is that the spatio-temporal patterns rival those

observed in other excitable media. Specifically, this premaxed gas-phase reaction exhibits many of the same features and

analogous dynamical behavior as numerous biological and chemical systems including the well-studied. Liquid-phase

Belousov-Zhabotinskii (BZ) reaction. Both these premixed gas flames and the BZ reaction exhibit chemical fronts which

spontaneously develop from single or multiple pacemaker sites into circular ring wave(s) or rotating spiral wave(s). This

is indicative of self-propagating waves of chemical activity in excitable media believed to affect such diverse phenomena

as the patterns of spots on animals, the spread of infectious disease, the formation of spiral galaxies, as well as the

rhythmic beating of a human heart and the solitary voltage pulses which travel along nerve fibers.

Radiative Flame Extinction at Large Droplet Radius - P. Struk (GSRP)

Objective:

To verify experimentally the existence of a limiting large droplet radius above which a spherical steady flame cannot be

sustained due to gas-phase radiative loss. Large fuel droplets are simulated using a wetted porous sphere continuously

supplied fuel by a syringe pump.

Description:

The research consists of two phases: a ground-based phase and a microgravity phase, The ground-based phase involves the

development of porous spheres, hardware buildup, as well as ascertaining the feasibility and techniques of using porous

spheres to simulate droplet burning. In the microgravity phase, wetted porous spheres are burnt in various atmospheric

conditions to ascertain a droplet flammability map based on droplet diameter. In microgravity, the radius of the droplet is

varied by adjusting the fuel flow rate to the porous sphere via the syringe pump.

11-313
Significance:

The verification of a limiting large droplet radius will contribute to our understanding of droplet burning and extinction, a

fundamental topic in combustion. It will also support the premise that gas-phase radiative loss alone can cause diffusion

flame extinction in gg.

FY94 Progress:

Hardware was designed, selected, and assembled. Two sets of experiments were performed during the ground-based phase in

normal gravity to demonstrate the feasibility of simulating fuel droplets using a wetted porous sphere. In both sets of

experiments, the fuel used was n-decane. The first set of experiments were performed at atmospheric pressure and used a

porous bronze sphere, 5 ram in diameter. A wetted fuel surface was not observed during an entire burn due to an excessive

heat feedback from the flame predominately due to the convective environment. The heat feedback, in turn, causes a high

fuel consumption rate which the syringe pump could not supply.

A second set of experiments were performed at roughly 1/3 atmospheric pressure and used a 4 mm porous bronze sphere. A

wetted fuel surface was observed during an entire burn at these conditions. Reducing the pressure decreased the mass

burning rate of the fuel (via chemical kinetics). At reduced pressure, the syringe pump could provide fuel to the porous

sphere at a rate equal to or greater than the consumption rate of the fuel. These results indicate the feasibility of

controlling the droplet radius in microgravity where convective effects are significantly reduced.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 0 MS Degrees: 0

PhD Students: 2 PhD Degrees: 1

TASK INITIATION: 1/91 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-22-05-08

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Ferkul, P.V. and T'ien, 1.S. A mode/or" low-speed concurrent flow flame spread over a thin fuel. Combustion Science and

Technology ( in print), (1994).

Hegde, U. Heat release effects on the instability of parallel shear layers. AIAA Journal (accepted), vol. 31 no. 1, 206

(January 1994).

Presentations

Vedha-Nayagam, M. and Hegde, U. "Effects of flee stream oscillations on heat transfer to a burning luel surface." Spring

Meeting of the Combustion Institute, Central States Section, June 1994.

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11-314
Combustion qf Solid Fuei in Very Low Speed Oxygen Streams

PRINCIPALINVESTIGATOR:Dr. Kurt R. Sacksteder NASA Lewis Research Center (LeRC)

CO-INVESTiGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this program is to obtmn expermaental experience and data to improve the understanding of the

mechanisms that control the spreading of flames and the flammability of materials in low-speed oxidizing flows,

including buoyantly-driven and forced concurrent flows and buoyantly-driven opposed flows.

TASK DESCRIPTION:

New and unique experimental apparatus are to be developed to obtain flame spreading observations in partial gravity

and in tbrced flows in microgravity. Partial gravity tests are to be conducted aboard NASA research aircraft flying

parabolic trajectories, altered from the traditional condition of near tree tall, to obtain the desired reduced levels of

acceleration. Low-speed t'orced flows are to be obtained in microgravity drop towers using mechanical devices to

establish purely-forced (non-buoyant) flows. In each instance, detailed measurements of flame ignition, spreading,

and limiting behavior are to be made.

TASK SIGNIFICANCE:

This work attempts to provide a fun "damental understanding of the practical flame-spreading environment of

low-speed flows including: purely buoyant flows in partial gravity (between microgravity and normal gravity), and

purely forced flows c)nly possible in microgravity. In normal gravity, buoyancy forces induce flows in spreading

flames having velocities of no less than 20-30 cm/sec. Interactions between flames and lower speed flows,

therefore, cannot be observed in normal gravity. In the low-speed flow regime, flow velocities approaching the

spreading velocity of the fl_unes can be ex_nined. These flames are expected to demonstrate entirely new

spread-rate limiting mechanisms, different than the normal-gravity counterpart. These tests are also expected to

demonstrate lower flammability limits of solid fuels than any observed in normal gravity. Additionally, this work

will attempt to distinguish between influences of buoyantly induced flows and flows of similar intensily that are

externally tmposed.

PROGRESSDURING FY 1994:

This task was completed during fiscal year 1994 with the award of a new flight expertment project entitled,

"Combustion of Solid Fuel in Very. Low Speed Oxygen Streams," under NRA-93-OLMSA-l, "Microgravity

Combustion Science: Research and Flight Experiment Opportunities."

At the transition to the flight progrmn, this task has achieved the Iollowmg major accomplishments:

1. A comprehensive testing program of flame spreading and flammability limit determinations for a thin fuel

burning in low-speed forced-concurrent flows has been conducted. These experiments include drop tower

expemnents in a microgravity wind tunnel, and experiments in a unique expertmental device, developed under this

program, with which the lowest speed flows are obtained by translating the burning sample through the oxidizing

environment. In these experiments a low-speed flammability limit has been observed lbr forced flows at about 12%

oxygen atmospheric mole fraction (normal air is 21% oxygen), far below the opposed-flow limit observed in

microgravity of about 15% oxygen. Flame spread rates were measured over a wide range of oxygen environments

and flow velocities. All forced-flow results were dominated by the ignition process because of the hmited testing

time available in the ground-based facilities.

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11-31 5
2.Acomprehensive testingprogramofflame spreading and flammability limit determinations for a thin fuel

burning upward in purely buoyant (concurrent) flows has been conducted. These experiments were conducted in an

_tircraft facility operating under partial-gravity conditions. These experiments have demonstrated reduced-gravity

upward-spreading flammability limits similar to those observed in the low-speed forced flow expertments, and

similar to the normal gravity upward spreading limit, all approximately 12% oxygen. At the reduced-gravity levels

obtainable in aircraft testing, (between 0.05 and 0.6 times normal Earth Gravity) the buoyant velocities are

sufficiently high that flammability limit and flame spread behavior are similar to normal gravity behavior, ie. finite

rate chemical reactions limited by reactant residence times. At these relatively high speed flows (even at 0.05 g)

flame spread rates are unsteady, because of either inherent unsteadiness or ignition effects. Until lower levels of

partial-gravity are made available, a transition to "low-but-not-zero" gravity behavior in concurrent flow flame

spreading cannot be observed.

3. A comprehensive testing program of flame spreading and flammability limit determinations for a thin fuel

burning downward in purely buoyant (opposed) flows have been conducted. These experiments were conducted in an

aircraft facility operating under partial-gravity conditions. These experiments have demonstrated increases in

flammability as the gravitational acceleration is reduced from normal Earth gravity, to a low of between 13% and

14% oxygen near 0.05 g compared to the normal gravity limit of 15.7% oxygen. Thus, in the case of downward

flame spreading, Lunar and Martian gravity levels present a greater ftre hazard than observed on Earth. Flame spread

rates also increase with reductions in acceleration from normal gravity, peak at some intermediate gravity level then

decrease with further reductions in gravity. In normal air (21% oxygen), these peak spread rates occur in the vicinity

of Lunar and Martian gravity levels.

4. Combining the results of items 2) and 3), this task has provided the first comprehensive measurements of flame

spread behavior of a single material over the full range of flow conditions from "high-speed" flows in the concurrent

direction, through low-speed flows in reduced gravity (transitioning from concurrent to opposed flow), to

"high-speed" flows in the opposed direction.

5. Based upon the results of the forced concurrent flow testing, a successful proposal was submitted for the

Spacelab/Middeck/Mir Glovebox Experiment program entitled, "Forced Flow Flamespread Test.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 5/89 EXPIRATION: 2/94

BS Students: 0 BS Degrees: 2 PROJECT IDENTIFICATION: 962-22-05-28

MS Students: 1 MS Degrees: 2 RESPONSIBLECENTER: LeRC

PhD Students: l PhD Degrees: 0

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Grayson, G.D.o Sacksteder, K.P-,.,F_rkul, P.V. and T'ien, J.S. Flame spreading over a thin solid in low speed concurrent

flow: Drop tower experimental results and comparison with theory. Microgravity Science and Technology, vol.7, no.2,

(1994).

Presentations

Sacksteder, K.R. and T'ien, J.S. "Downward diffusion flame spread and extinction in variable gravitational fields: Lunar

and martian simulations." presented to the AIAA 31st Aerospace Sciences Meeting and Exhibit, AIAA-93-0828. 1993.

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11-31 6
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

Reduced Gravity Combustion with 2-Component Miscible Droplets

PRINCIPALINVESTIGATOR:Prof. Bexiiamin D. Shaw University of California. Davis

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective is to improve understanding of the combustion of two-component miscible droplets in reduced

gravity. We will consider both experimental and theoretical aspects of the combustion behaviors.

TASK DESCRIPTION:

Reduced-gravity experiments will involve burning two-component miscible droplets in environments of differing

pressures and compositions. Data will be obtained by direct photography of droplets and flames. Droplets with

components that differ significantly in volatility and which are initially in the millimeter-size range will be studied.

Data will be collected on the following: transient liquid behaviors (e.g., diameter histories and disruption), transient

flame behaviors (e.g., sudden flame contraction and extinction), and sooting (e.g., luminosity and transport of

observable soot particles).

Hydrocarbon (e.g., heptane/hexadecane) or alcohol mixtures in oxygen mole fractions from about 0.1 - 0.5 and

initial pressures fi'om 0.5 - 2 aim are to be used. Different inerts will be used in the gas phase to enhance or mhibit

certain phenomena; e.g., CO2 may inhibit soot lbrmation, while helium may promote extinction by increasing gas

transport rates. Theoretical and computational research in support of this program will also be undertaken. This

research includes: modeling of fundamental droplet combustion phenomena; studies of 'allowable acceleration levels

and durations to define experiment requirements; and studies of issues such as allowable droplet oscillation

amplitudes, oscillation decay times, and pre-ignition vaporization; development of a new droplet combustion

apparatus for use in the NASA Lewis 2.2-Second Drop Tower Facility was undertaken at the request of the

cognizant NASA monitor ',tiler the original proposal was awarded.

TASK SIGNIFICANCE:

The reduced gravity experiments should yield insight into the efficiency of liquid-phase species diffusion, since this

diffusion may markedly influence combustion behaviors (e.g., three-staged combustion behaviors). By noting tunes

for flame contraction to occur, calculations lbr effective liquid-phase species diffusivities may be made (e.g., with

asymptotic or with numerical models). Finally, unique sooting behaviors may appear since gas-phase

compositions may differ significantly with time. Differences in sooting may be observable photographically by

noting behaviors of apparent flame luminosities and soot particles large enough to be observed.

The theoretical et'fo_s will aid interpretation of the reduced-gravity experiments as well as improve understanding of

the fundamental phenomena that occur during droplet combustion in reduced-gravity.

PROGRESSDURINGFY 1994:

Experimental:

A digital image analysis system has been constructed and used for analysis of films that were taken of preliminary

experiments perlbrmed using a NASA-supplied drop apparatus.During fiscal year 93/94 a new drop apparatus was

designed and built lbr use in the NASA Lewis 2.2 sec drop tower. The apparatus was constructed at UC Davis. The

electronics on the apparatus, except Ibr some modifications, are based on the design of a NASA apparatus. The

mechanical design is completely new though it is based on knowledge and experience accumulated at NASA. The

drop apparatus is now being used for expertments.

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ii-31 7
Experimentsarebeingdonewithdifferentinitialenvironmental compositions andpressures. Initialoxygen mole

fractions ti'om about 0.1 to 0.5 _md initial pressures from 0.5 to 2 atrn are being used. Different inert.,; are used in

the gas phase to enhance or inhibit certain phenomena. For example, helium may promote extinction and higher

burning rates, while CO2 may inhibit soot formation. Flame contractions and droplet disruptions have previously

been observed lor initially-pure heptane or decane droplets burning in low-gravity environments. These behaviors

have been postulated to result from sooting effects. If this is correct, flame contractions and droplet disruptions

arising from surface buildup of the less volatile component in a binary, fuel droplet may be influenced to an

unknown extent by sooting, making interpretation of experimental results difficult. Experiments are being

performed to search for conditions where sooting appears to influence combustion negligibly.

Detailed computational modeling (in collaboration with Dr. H. A. Dwyer) has focused upon predicting the effects of

capillary flows (from droplet surface temperature and/or composition gradients) on droplet vaporization. Calculations

of single-component droplet vaporization in a hot environment have clearly shown that surface-tension gradients can

dramatically influence droplet vaporization and internal circulation behaviors under conditions that are representative

of slowly-drifting droplets in reduced-gravity experiments as well as rapidly-translating droplets in practical

high-pressure sprays. These calculations are now being extended to combustion of two-component miscible

droplets, for which surface-tension gradient effects are expected to be especially significant.

To aid interpretation of experimental etTorts, analytical studies of the behaviors of gasifying droplets in

reduced-gravity environments are being performed. These efforts are focused on studying: (I) effects of small

gravitational levels on droplet vaporization/combustion; and (2) hydrodynamic stability of spherically-symmetric

vaporization/combustion of two-component droplets. Each eftort is presently focused upon modeling evaporating

droplets; combustion will be considered in the future. The gravity-level research is expected to provide scaling

relations for the effects of small gravitational accelerations on vaporization rates and gas-phase structures. The

stability analyses address the problem of hydrodynamic stability of a multicomponent mixture droplet during

evaporation/combustion; specifically, the question is addressed as to whether spherically-symmetrical

evaporation/combustion is hydrodynamically stable.

The studies of gravitational effects involve solving the equations for conservation of energy, mass and momentum

(Navier-Stokes) using singular perturbation techniques. We are presently focusing on steady gravitational levels and

stationary droplets, though oscillatory gravity levels and/or slowly drifting droplets will be studied in the future.

The governing equations are made dimensionless and relevant dimensionless parameters are identified. Analysis

shows that when gravity levels are small, an appropriate small parameter of expansion is a Richardson number (Ri

= gR/Lrs**2 = buoyancy/momentum) based upon the droplet radius R. the radial gas velocity at the droplet surface

Us, and the gravitational acceleration g. Using this parameter it is shown that distinct spatial regions exist where

different physical phenomena are dominant. Near a droplet, radial velocity gradients are sufficiently large such that

gravitational effects are small, and in the t-trst approximation the gas-phase solution can be considered to be

spherically symmetric. Far away from the droplet, however, viscous and pressure-gradient terms in the momentum

equation become of the same order as the buoyancy term. Different zones therefore exist, allowing techniques of

matched asymptotic expansions to be used. This methodology is currently being followed for analysis of droplets

vaporizing in hot alanospheres. When this analysis is completed, the calculations will be extended to droplet

combustion.

As noted above, the analysis has demonstrated that for the case of droplet gasification in a hot environment, distinct

spatial zones exist. Spherical symmetry prevails in the first approximation near a droplet. Far away from a droplet,

however, gravity effects become important and a stagnation point is predicted to form in the flow for any nonzero

gravity level regardless of its magnitude; the location of this stagnation point is predicted to scale as Ri**(-1/3).

The inner (spherically symmetric) zone and an outer zone that includes the stagnation point have been analyzed.

Another zone exists further out where the flow appears to resemble a viscous plume driven by natural convection,

for example similar to what would exist around a heated or cooled sphere. We are presently in the process of

investigating this zone and matching the solution to the inner zones to provide a complete description of the

flowfield and its influences on droplet gasification.

11-318
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

The hydrodynamic stability analysis was carried out using linear stability theory. The normal-mode method was

used in the analysis. The disturbance equations for conservation of mass, momentum, energy and species m the

liquid and gas phases were derived trom the general governing equations, written in spherical coordinates, by

introducing small disturbances. Furthermore, the disturbance equations were linearized and nondimensionalized. Bv

assuming a certain type or" solution and using the spherical harmonic decomposition together with the quasisteady

assumption in the gas phase, the partial differential equations were transformed into a set of linear second order

nonhomogeneous ordinary differential equations. By taking advantage of the special properties of the spherical

harmonic decomposition for solenoidal velocity fields, the 3-dimensional problem was reduced to a 1-dimensional

problem in the radial coordinate.The disturbance equations were solved using different methods. In the gas phase

negligible terms were dropped from both the energy and species equations, simplifying them to standard

nonhomogeneous Euler equations. In the liquid phase the boundary-layer nature of the problem in the species

equation was identified, and consequently a solution using matched asymptotic expansions was adopted for this

equation. The energy equation in the liquid phase was solved by using a truncated Frobenius series. For both phases

the momentum equation was simplified to a biharmonic equation which could be solved analytically.

The interlace conditions between the two phases were defined accounting for balances of mass, momentum and

species, complemented with the equations accounting for tangential stresses, tangential velocities and temperature.

Here again, use was made of the spherical harmonic decomposition representation and its special properties for

solenoidal fields.

These efforts have allowed an analytical solution to be developed for the growth factor in the stability analysis. This

solution is presently being investigated to find the marginal stability curve under various conditions. It has

tentatively been found that certain binary mixtures are anticipated to be stable, while others may be unstable.

Stability is influenced both by surface-tension gradients as well as by viscous stresses that occur from uneven

surface vaporization rates.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/91 EXPIRATION: 3/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-22-05-39

MS Students: 0 MS Degrees: 1 NASA CONTRACTNO.: NCC3-245

PhD Students: 2 PhD Degrees: 0 RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Niazmand, H,. Shaw, B.D.. Dwyer, H.A., and Aharon, I. Effects of Marangoni convection on transient droplet

evaporation. Combustion Science and Technology, (accepted).

Presentations

Niazmand. H.. Shaw, B.D. and Dwyer, H.A. "Effects of Margangoni convection on transient droplet evaporation in reduced

gravity." Paper presented at the Fall Meeting of the American Chemical Society, Chicago, I11, August 22-27.1993.

Niazmand, H., Shaw, B.D. and Dwyer, H.A. "Effects of Marangoni convection on transient droplet evaporation at elevated

pressures and with negligible buoyancy." Paper 93-083 presented at the 1993 fall meeting of the Western States Section

of the Combustion Institute. SRI International, Menlo Park, CA, 1993.

11-319
Quantitative Measurement of Molecular Oxygen in Microgravity Combustion

PRINCIPALINVESTIGATOR: Dr. Joel A. Silver Southwest Sciences, Inc.

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

There are two objectives regarding this task. The Iirst is to develop a diagnostics based on diode laser absorption

spectroscopy lor use in microgravity combustion research. The general technique is expected to be applicable to

major gases involved in combustion and in spacecraft cabin environments. The specific application of this task is

directed to the quantitative determination of molecular oxygen. The second objective is to develop an improved

understanding of the relative roles of diffusion and reaction of oxygen in microgravity combustion. Oxygen has a

maior role in controlling flame properties such as flame front speed, extinguishment, flame size, and temperature.

TASK DESCRIPTION:

This investigation revolves the determination of molecular oxygen using diode laser absorption spectroscopy. This

technique uses a compact, low power optical system to probe the near infrared bands of oxygen. Though these

bands are relatively weak, high sensitivity is maintained by means of wavelength modulation of the diode laser with

detection at twice the modulation frequency. A compact laser scanner permits the laser beam to traverse the entire

flame region. This scanner eliminates the need to use multiple optical fiber lines-of-sight in the setup. A compact

electronics package includes all control, detection, and data acquisition electronics.

TASK SIGNIFICANCE:

Oxygen, as the primary oxidizer in flames, controls the major flame properties such as flame-spread, flame-front

speed, temperature, and its extinguishing properties. Theretbre, its quantitative determination is necessary for both

an improved understanding of flame behavior in general, and Ior tire safety on board spaceceati. Oxygen

measurement is also critical lor ground-based applications such as engine efficiency, energy production, air quality

monitoring, and industrial processes such as steel manufacturing. The specific technique under development is a

compact, lightweight, and rugged instrument offering a wide range of laboratory., field, and industrial process

measurements.

PROGRESSDURING FY 1994:

Optimum spectral lines for simultaneous measurement of temperature and 02 concentration have been computed.

Four pairs of lines have been identified which show appropriate temperature sensitivity. Expected temperature

accuracy is +_25 K. Optimum lasers for these lines have been ordered.

The PI is investigating the possibility of using Vertical Cavity Surface-Emitting Lasers (VCSEL's) as a potential

replacement for the conventional laser diodes. The VCSEL's show promise of increased long-term reliability, wider

tuning range, better beam profile, and reduced mode-hopping.

Optical and mechanical design has been completed and components have been ordered, received, or fabricated.

Assembly is underway. Various lens types have been tested for laser focusing.

IlJJJlllJOlllllllljlllJl JllJll II IJ Jl Itl II III II I IO I I II I I I I I I Ill I I III II I I I I I I I I l I iI l III Itl Ill }JlJJlJ Jl I JI I JI I II I li IJ I Ill II Ill IiJl III Jill Ill IlllllJl Jill I II J Ill Ill Ill IIIlllOIllllJll IlllJllllllJJll Jllll IlJJJJll Illllllll I Ill IIIIII IIIll Ill Ill I II I IFIII

11-320
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 6/97

PROJECT IDENTIFICATION: 962-22-05-5l

NASA CONTRACT NO.NA53-26553

RESPONSIBLECENTER: LeRC

_______________________________Ill_!_ill_i____________________________!_____i__i_______________!____Ill_______!_!_______!___i_____!______ _______!__i!i______________________!______!_______i____!__________________!_________Ill_i__i______!___!i_!i

II-321
lI. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

Numerical Modeling of Flame-Balls in Fuel-Air Mixtures

PRINCIPALINVESTIGATOR:Prof. Mitchell D. Smooke Yale University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of the proposed work is to understand it and the mechanisms by which stationary, spherical flames,

sometimes called flame balls, stabilize in a quiescent, premixed gaseous fuel-oxidizer environment. These flames

have been observed experimentally shortly after ignition in microgravity, but their long-term persistence is as yet

undetermined.

TASKDESCRIPTION:

The approach to meet this objective is to modify an existing numerical model, which includes full chemical

kinetics, to account for radiative heat losses. The predictions will then be compared to the experimental

observations of Prof. P. Ronney as well as theoretical results developed by Prof. J. Buckmaster.

TASK SIGNIFICANCE:

The significance of this eltort is to enhance the understanding of very. basic combustion phenomena, such as:

flammability limits and stabilization mechanisms, and the probability that it will find its way into combustion

science textbooks.

PROGRESSDURING FY 1994:

The ignition of near limit hydrogen/air mixtures can lead to the formation of "flamecaps"--discrete curved flames

small on the scale of the confinement vessel which rise because of buoyancy. Recently it has been shown that, in

low gravity, when buoyancy effects are small, flameballs can be generated. Flameballs are stationary spherical

structures whose existence appears to require the following ingredients: a near-limit mixture: small Lewis number:

and radiative, convective, and conductive losses. Flameballs have been observed in a variety of mixtures. For

example, HJair, H2/OJCO> HJOJSF_, and CH4/OJSFe.

Numerical solutions of flamebalis have been constructed/or H:/air mixtures using an accurate description of

chemical kinetics, diffusive transport, and radiation losses. A previously-developed code has been modified tor plane

flames to account for the spherical geometry, radiation, and the absence of a flow field. A lean limit equivalence

ratio of 0.0866 was predicted and a rich limit of 2.828, For any equivalence ratio between the two limits there are

two solutions. One is characterized by a small flame, incomplete reactant consumption, and negligible radiation

losses. The other is characterized by a large flame, complete consumption of one of the reactants, and significant

radiation losses. The maximum temperature varies between 1200 and 900 K as the two solution branches are

traversed. There is evidence that the kinetic mechanism adopted here is not as accurate as it might be at low/lame

temperatures. Also, there are some uncertainties in the present description of the radiation transport.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 4/98

PROJECT IDENTIFICATION: 962-22-05-60

RESPONSIBLECENTER: LeRC

, i i ill iii ill iii Ill ill l i I II I I QI IIIIII I i llill Itl III ii I Ili I I II .I II iil I i I Iil ii I I iQl i I i I I II i I I Ii I. I I l i I ii I I i I I QIII I III I Ii I I I I I I I IQI Ii l ii I I II I Iil Ill I I I QI I i II i II QI II I II II I III I QI Ill Iltl I ii I I I I i II II QIS ii. il I il I II I I II I I I QII III ill II I II I I I I Ill I II III i Iii I ii

11-322
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

Combustion q( Solid Fuel in Very Low Speed Oxygen Streams

PRINCIPALINVESTIGATOR:Prof. James S. T'ien Case Western Reserve University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this program is to develop a theoretical model to improve the understanding of the mechanisms

that control the spreading of flames over solid fuels and the flammability of materials in low-speed oxidizing flows,

including buoyantly driven concurrent and opposed flows and forced-concurrent flows.

TASK DESCRIPTION:

A numerical simulation of the concurrent-flow flame spreading process is to be developed that accounts for both the

stabilization of the flame at the leading edge facing the flow and the downstream Up of the flame where the flame

spreading occurs. The required computational domain must therefore be large in comparison to the opposed-flow

case. A steady solution will be formulated and solved first, followed by a transient version. The model is to

accommodate first thin and then thick fuels.

TASK SIGNIFICANCE:

The work attempts to provide a fundamental understanding of the practical flame-spreading environment of low

speed flows including: purely buoyant flows in partial gravity (between microgravity and normal gravity), and

purely forced flows only possible in microgravity. In normal gravity buoyancy forces induce flows in spreading

flames having velocities of no less than 20-30 crn/sec. Interactions between flames and lower speed flows,

therefore, cannot be observed in normal gravity. In the low speed flow regime, flow velocities approaching the

spreading velocity of the flames can be examined. These flames are expected to demonstrate entirely new spread-rate

limiting mechanisms, different than the normal-gravity counterpart, These tests are also expected to demonstrate

lower flammability limits of solid fuels than any observed in normal gravity. Additionally, this work will attempt

to distinguish between influences of buoy;mdy induced flows and flow of similar intensity that are externally

imposed.

PROGRESSDURINGFY 1994:

This task was completed dunng tiscal year 1994 with the award of a new flight experiment project entitled,

"Combustion of Solid Fuel in Very Low Speed Oxygen Streams." under NRA-93-OLMSA-1, "Microgravity

Combustion Science: Research and Flight Experiment Opportunities."

At the transition to the flight program, this task has achieved the following major accomplishments:

1. A complex numerical model has been developed and tested, simulating flame spreading over thin fuels in

low-speed concurrent flow. This model includes the lull elliptic Navier Stokes equations in the leading edge region

of the flame, transitioning to a parabolic, boun "dary layer formulation downstream to accelerate the computations.

The model contains a finite-rate, single-step gas-phase chemical reaction, surface radiation losses, and is able to

predict flame spreading behavior, including detailed flame structure over the entire flammable range of concurrent

flow velocities at low oxygen concentrations. The model has predicted flammability limits based on blowoff

extinction at higher speed flows (similar to observed behavior in normal gravity conditions) and the unique

microgravity phenomenon of quenching attributed to the radiative losses at the very low-speed flow velocities. At

the time of transition to the flight program, the boundary conditions of the model have been reformulated to permit

computations at varying levels of gravitational acceleration.

II-323
[I. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

2. Based on these computational results, and the related experimental work, a successlifl proposal for continued

development of the theoretical model to include transient behavior and gas-phase radiation processes and the

development of a new flight experiment to obtain observations of forced-concurrent flow flame evolution and

spreading was submitted to the NRA-93-OLMSA-1 competition.

STUDENTSFUNDEDUNDER RESEARCH:

BS Students: O BS Degrees: 0

MS Students: 0 MS Degrees: 1

PhD Students: 1 PhD Degrees: 2

TASK INITIATION: 5/89 EXPIRATION: 2/94

PROJECT IDENTIFICATION: 962-22-05-25

NASA CONTRACT NO,: NAG3-1046

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Grayson, G,D., Sacksteder. K.R., Ferkul, P.V., and T'ien, J.S. Flame spreading over a thin solid in low speed concurrent

flow: Drop tower experimental results and comparison with theory. Microgravity Science and Technology, vol. 7, no. 2.

187-195 (1994).

Presentations

Garbinski. G. and T'ien. J.S. "Ignition and extinction of diffusion flames with radiative losses." Presented at the AIAA

32nd Aerospace Sciences Meeting, AIAA-94-0577, 1994.
lI. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

Interactions Between Flames on Parallel Solid Surfaces

PRINCIPALINVESTIGATOR:Dr. David L. Urban NYMA, Inc.

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of the proposed research is to study the interactions between flames which are spreading or established

over parallel solid surfaces and to determine the relative importance of radiative and convective heat exchange versus

the potential reduction of oxidizer due to the presence of the second fuel surface. The results from this work will

be used to improve existing models of flame spread over solid surfaces and to improve our understanding of fire

spread and growth for practical fuel geometries.

TASK DESCRIPTION:

Low gravity testing will be conducted at the NASA LeRC drop towers and on NASA's low-gravity research aircraft.

This work will determine the dependence of flame spread over parallel sheets on geometric parameters such as height

and width and to use this understanding to select the optimum configuration for more extensive test,;. These tests

will determine the dependence of spread rate for parallel surIaces on fuel thickness, separation distance, oxidizer flow

direction and rate and gas phase radiation. In addition, the controlling factors in the unstable regime at close surface

separations will be established. Tests will "also be conducted to determine the llame structure and burning rate lot

flames established over parallel thick fuels with forced flow between the plates. Finally, these results will be

combined with numerical/analytical results to determine the importance of radiative feedback, between interacting

/lames and surfaces, on flammability and spread and burning rates.

TASK SIGNIFICANCE:

The interaction between flames on solid surfaces is of considerable practical importance since in most practical

heterogeneous combustion systems, the condensed phase is distributed in more than one piece and this spatial

distribution can strongly affect burning and/or spread rate. From a fundamental viewpoint, the interaction between

parallel surfaces offers opportunities to simplify the boundary conditions, over those for isolated surfaces, a.s the

opposing surfaces impose a plane of symmetry between the two sur/hces and if the surfaces are sufficiently large,

the radiation shape lhctors between the surfaces and between the flame and the surfaces approach unity. This

geometry also provides interesting and unique opportunities to explore the relative effects of reactant diffusion

rates, radiative heat transport and conductive transport in flame spread; these transport mechanisms have been

identified as critically important in microgravity.

These phenomena will be more readily studied in nonbuoyant flames as the buoyant transport will be removed,

simplifying analysis and increasing the importance of conduction and radiation, In the absence of strong buoyant

flows, the interaction between flames on opposing sheets extends to greater separauon distances, providing greater

opportunities to study the interaction via the greater spatial resolution al'torded by microgravity.

These results will be significant to low gravity flame spread research in general as the parallel geometry with its

plane of symmetry between the fuel surfaces is in some terms simpler than the traditional case of a single sheet in

an infinite oxidizer. The results will be an extension of the existing body of knowledge concerning flame spread

and burning rate over flat surfaces. The work might also have practical benefits as radiant preheaung is also very

significant in t_e spread in building tires. Due to the significance of flame interaction in terrestrial fire sal'ety, it is

important that flame interactions be studied in low gravity to assess their importance in spacecra/t fire safety.

11-325
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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PROGRESSDURINGFY 1994:

Tests were conducted on the KC-135 using the Spacecraft Fire Safety Facility (SF) _ on its first flight campaign.

The tests were very. successful, further tests are planned once data analysis has been completed. Samples were burned

at one atmosphere in air under flows of 5 and 10 cm/s. Samples were/or a variety of separation distances and

included single double and triple interacting sheets.

The video tapes from the KC-135 campaign were analyzed to determine spread rate. Instability and oscillating

flames were seen at low pressures near the flammability limit.

A large number of 1-g tests were conducted in air at various separation distances and pressures. The flammability

limit as a function of pressure and separation has been mapped out for these conditions. At large separations, spread

rate is largely independent of pressure until extinction, however at small separations, the spread rate exhibits the

change in pressure dependence seen in low gravity.

Over the summer, 170 1 and 0-g tests were conducted at various separation distances and pressures and oxidant

concentrations. The low gravity test program expanded the test matrix at 30% oxygen and added points at 21%

oxygen. The test program was limited by the current unavailability of gas mixing capabilities in the NASA LeRC

2.2-Second Drop Tower.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 5/98

PROJECT IDENTIFICATION: 962-22-05-52

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Urban, David L. "Interactions between flames spreading over parallel solid sheets of paper in microgravity." A poster

presentation was presented at the 25th International Symposium on Combustion.

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11-326
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

Gasless Combustion Synthesis from Elements Under MicroEravity: A Study of Structure-Formation

Processes

PRINCIPALINVESTIGATOR:Prof. Arvind Varma University of Notre Dame

CO-INVESTIGATORS:

Dr. Paul J. McGinn University of Notre Dame

TASK OBJECTIVE:

The objective is to understand the mechanisms ot structure tormation during combustion synthesis from elemental

powders, in order to find the most promising ways to control the microstructure and properties of advanced

materials. Many fundamental questions may be answered by elucidating the reaction mechanism under microgravity

conditions, where complicated processes caused by gravity can be ignored.

TASK DESCRIPTION:

The reaction systems have been studied previously under normal gravity conditions, and the results have shown that

combustion and structure formation mechanisms revolve several stages including melting of reactants and prcxlucts,

spreading of the melt, droplet co',,descence, diffusion and convection, buoyancy of solid particles and bubbles in the

melt, nucleation of solid products, and crystal growth. Most of these processes are affected by gravity.

Microgravity experiments will permit the general mechanisms of structure formation to be obtained without the

disturbing effects of gravity.

The experimental program includes two approaches: macrocombustion, involving combustion synthesis of pellets

pressed from reactant powders, and novel microcombustion experiments where reactions of individual reactant

particles are studied. Both approaches will be carried out under normal and microgravity conditions.

TASK SIGNIFICANCE:

The research results will be helpful to U.S. industry in its efforts to produce advanced materials with unique

properties. They will also establish whether better materials can be produced under microgravity conditions. Both

poreless cast and porous loam materials will be developed from the project. These have a significant potential for

use as high temperature materials in aerospace and other industrial applications ()wing to their excellent mechanic',d,

thermal, and chemical properUes. The research effort wi[l also help to answer many fundamental questions in the

field of combustion synthesis.

PROGRESSDURING FY1994:

Purchase of equipment, system design, and some normal gravity experiments were carried out since the grant was

awarded in July 1994. The design of the reaction chamber tot the NASA LeRC 2.2-Second Drop Tower was

initiated. A computer and data acquisition board were purchased; other equipment including a video recording

system, data acquisition, image analysis system, and power supply will be purchased early in FY 95.

Combustion synthesis of the Ni-AI system was earned out. Elemental Ni and AI powders, as well as cladded Ni/AI

composite powders, were both used as reactants. These powders were then pressed into green pellets with densities

about 77% of theoretical, and then ignited in an inert atmosphere. The combustion of elemental powders propagated

in a spin mode. In contrast, combustion of cladded particle pellets occurred in a rather complex mode which has

never been reported. Firstly, the pellets were more difficult to ignite. Secondly, the ignition position was not

always at the same end as the ignitor. Ignition sometimes occurred at the opposite end or at some distance away

from the ignitor. Thirdly, the combustion wave propagated in a complex mode.

The product microstructures were determined by X-ray diffraction, SEMt and optical microscopy. A structure

lormation sequence was observed for the cladded particles. Namely, intermediate phases were l/rst tormed before the

11-327
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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microstructure attmned the final equilibrium phases. No difference m linal equilibrium microstructures was found

between the samples from cladded and elemental powders.

The reasons for the above phenomena are still being investigated. Further experunental work must be done in order

to understand the governing mechanisms,

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 6/96

BS Students: 3 PROJECT IDENTIFICATION: 962-22-05-56

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

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11-328
lI. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

Studies of Wind-Aided Flame Spread Over Thin Cellulosic Fuels in Microgravity

PRINCIPALINVESTIGATOR:Prof. lndrek S. Wichman Michigan Slate University

CO-INVESTIGATORS:

Prof. Columbo DiBlasi University of Naples

TASK OBJECTIVE:

The objective of this research is to develop fundamental theoretical models for wind-aided flame spread over thin

solid fuels in low gravity. An important aspect of this study is to develop detailed models lbr the combustion

process in the flame anchoring region, the so-called "Triple-Flame" zone and for the fuel pyrolysis chemistry.

TASK DESCRIPTION:

The theoretical modeling eftort will explore two tracks, one fun "damental, the other directly concerned with the

wind-aided flame spread calculations. The fun "damental part will be detailed examination of the triple flame problem

near the leading edge of the spreading flame. The results of this model should provide the heat flux distribution to

the supporting fuel surface. The solution techniques employed will be asymptotic and approximate methods

combined with numerical methods. The second model to be examined will be wind-aided flame spread calculations.

An order-of-magnitude analyses of the goveming equations will be perlormed to identify the correct scaling of the

wind-aided flame spread problem, particularly near the flame attachment point. The properly scaled equations will

be solved numerically to obtain flame spread rates. The results of this study will be compared against experimental

data obtained in low gravity facilities at the NASA Lewis Research Center as a part of other on-going programs.

TASK SIGNIFICANCE:

Theoretical models for the combustion process occurring at the flame anchoring point will be developed to better

understand the triple flame structure. Using this basic model, numerical codes will be developed to predict

wind-aided flame spread rates over thin solid fuels.

PROGRESSDURING FY 1994:

A preliminary version of a monograph (~100 pages) reviewing the current state of knowledge of triple llame

structure was prepared by the PI. This monograph identifies the critical areas for future research. Two graduate

students have started working on various aspects of the triple flame structure.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 3/94 EXPIRATION: 3/98

BS Students: 0 PROJECT IDENTIFICATION: 962-22-05-53

MS Students: 2 RESPONSIBLE CENTER: LeRC

PhD Students: 0

11-329
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

n111111 j|_l_n_tg!_l|_t_u_|_o_IQn|I_In_i_n_I|_|I_o_lo_|_I_I_inIn_o_ j_l_nl6_H_I_llIll_l_l_n_Inn|l_ln_n*l_l_o_u_I_Ill_ll_l_l_In_H_I_H_I_ll_IlIll_l_I_l_l|_l_llonlI_II

High Pressure Droplet Combustion Studies

PRINCIPALINVESTIGATOR: Prof. Forman A. Williams University of California, San Diego

CO-INVESTIGATORS:

Prof. M. Kono

Prof. T. Niioka

University of Tokyo, Japan

Tohoku University, Japan

TASK OBJECTIVE:

The focus of this international cooperative eftbrt is on high-pressure combustion of miscible binary fuel droplets.

This is a joint research program pursued by investigators at the University of Tokyo, the University of Tohoku, the

University of California, San Diego, and the NASA Lewis Research Center (LeRC). It involves construction of an

experimental apparatus in Tokyo and mating of the apparatus to a NASA-LeRC 2.2-Second Drop Tower in

Cleveland. Experimental results are to be analyzed jointly by the Tokyo, UCSD, and NASA investigators. The

project was initiated in December, 1990, and has now involved three periods of drop-tower testing by Mr. Masato

Mikami (U. of Tokyo) at LeRC.

TASK DESCRIPTION:

The research accomplished thus tar concerns the combustion of individual fiber-supported droplets of mixtures of

n-heptane and n-hexsadecane, initially about 1 mm in diameter, under free-fall microgravity conditions. Ambient

pressures ranged up to 3.0 MPa, extending above the critical pressures of both pure fuels, in room-temperature

nitrogen-oxygen atmospheres having oxygen mole fractions, X, of 0.12 and 0.13.

TASK SIGNIFICANCE:

The general purpose is to study near-critical and super-critical combustion of the droplets and to see whether

three-stage burning, observed at normal gravity, persists at high pressures in microgravity.

PROGRESSDURING FY 1994:

Masato Mikami of the University of Tokyo pertormed drop tower tests on the burning ot droplet arrays of a

bicomponent fuel at high pressures. The experimental apparatus was modified to incorporate two video cameras

instead of the cine cameras (which necessitated changes to the electronics, camera mounts and the installation of

fiber optic transmitters). The gas mixing system, removed dunng the drop tower construction, was also

reassembled for the tests.

After modifications to his experimental apparatus were complete, M. Mi 'kami pertormed experiments on a two

droplet array of two mixtures of heptane/hexadecane (0.80 and 0.90 heptane by volume) at pressures ranging ti'om 1

to 50 atrn (above the critical pressures of both fuels). The three staged burning exists/or the droplets with in many

cases the flames initial separate, then merging during the fu'st stage, then the flames separate dunng the second stage

and merge again during the third stage. Masato returned to Tokyo at the end of September, when he will begin

preparing his Ph.D. thesis.

The data taken during August and September was analyzed. It is likely that more data will be required as the success

rate was only 50%. This results mainly from the difficulty in igniting the droplets at high pressure.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 10/89 EXPIRATION: 12/94

PROJECT IDENTIFICATION: 962-22-05-41

RESPONSIBLECENTER: LeRC

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11-330
II. MSADProgramTasks-- Ground-based Research Discipline: Combustion Science

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High-Pressure Combustion qf Binary Fuel Sprays

PRINCIPALINVESTIGATOR:Prof. Forman A. Williams University of California, San Diego

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of the proposed research is to improve understanding of the combustion of sprays of multi-component

tuels at elevated pressures, extending from normal atmospheric pressure to pressures above the critical pressure of

the fuel. In particular, explanation of the role of previously observed three-stage droplet combustion behavior and

microexplosion in spray combustion is sought. The extent to which buoyancy influences the phenomena that

occur is to be determined.

TASK" DESCRIPTION:

The objective is to be achieved by theoretical analyses taking into account concentration profiles of fuel

constituents within the liquid, instabilities, droplet interactions, and conditions for achieving the limit of superheat,

'along with drop-tower experiments employing 1.4 and 2.2-Second Drop Towers. Binary. mixtures of heptane and

hexadecane will be studied first, using fiber-supported droplets of diameters from 0.8 mm to 1.5 mm m air at

pressures from 0.1 to 5 MPa. Later work is planned to involve free droplets and other fuels and possibly

microgravity lhcilities that afford longer test times.

This program is a.joint program with several investigators in Japan. The Science and Technology Agency of Japan

is supF)rting research bv Dr. Michikata Kono, Professor, Department of Aeronautics. The University of Tokyo,

Tokyo, Japan, Dr. Takashi Niioka, Professor, Institute of Fluid Science, Tohoku University, Sendai, Japan, and Dr.

Jun'chi Sato, Senior Researcher, Heat and Fluid Dynamics DepartmenL Research Institute, Ishikawajnna-Harima

Heavy Industries Co., Tokyo, Japan on "Combustion of a Fuel Droplet in High-Pressure Atmospheres under

Microgravity Conditions" and on "Ignition of Fuel Droplets in High Pressure, High-Temperature Environments."

TASK SIGNIFICANCE:

The proposed research will improve our understanding of the mechanisms of the combustion of high pressure fuel

sprays, such as those found in diesel and gas turbine engines.

PROGRESS DURING FY 1994:

Masato Mikami of the University of Tokyo performed drop tower tests on the burning of droplet arrays of a

bicomponent fuel at high pressures. The experimental apparatus was modified to incorporate two video c_uneras

instead of the cine cameras (which necessitated changes to the electronics, camera mounts and the installation of

fiber optic transmitters). The gas mixing system, removed during the drop tower construction, wa.s also

reassembled for the tests.

Alter modifications to his experimental apparatus were complete, M. Mi 'kami performed experiments on a two

droplet array of two mixtures of heptane/hexadecane (0.80 and 0.90 heptane by volume) at pressures ranging from 1

to 50 atm (above the critical pressures of both fuels). The three staged burning exists for the droplets with in many

cases the flames initial separate, then merging dunng the first stage, then the flames separate during the second stage

and merge again during the third stage. Masato returned to Tokyo at the end of September, when he will begin

preparing his Ph.D. Thesis.

The data taken during August and September was analyzed. It is likely that more data will be required since the

success rate was only 50%. This results mainly from the difficulty in igniting the droplets at high t_ressure.

Z_/"__

II-331
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/94 EXPIRATION: 11/98

PROJECT IDENTIFICATION: 962-22-00

RESPONSIBLECENTER: LeRC

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11-332
Laser Diagnostics for Fundamental Microgravity Droplet Combustion Studies

PRINCIPALINVESTIGATOR:Dr. Michael Winter United Technologies Research Center

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

This research program seeks to investigate the range of applicability of advanced diagnostics to droplet combustion

under microgravity conditions while generating fundamental information relevant to other ongoing NASA

programs. Using a progressive approach, advanced laser diagnostics will progress from laboratory., to flight

experiments, and ultimately to drop tower lacilities. In this way, these diagnostics can be developed, while

providing fundamental data on droplet transport and combustion phenomena. Through consultation with NASA

personnel, and other researchers in the fields of microgravity droplet transport and combustion, priorities have been

established with respect to measurement parameters. The prioritized measurement parameters are:

1. Flame front position.

2. Relative gas-phase flow around droplets.

3. Droplet surface transport and internal flow.

4. Liquid-phase thermometry.

TASK DESCRIPTION:

An integrated diagnostic unit, capable of per_brming these measurements has been assembled. All of the major

components such as lasers, detectors and data systems, are currently allocated to this effort. A self-contained,

miniature, nitrogen-pumped dye laser system and two-dimensional intensified CCD imaging system will form the

core of the unit.

The testing program is proceeding with ever more challenging environments proceeding from the lg lalx)ratory, to

aircraft, and finally, to drop tower facilities. The diagnostic approaches and instrumentation are being verified in a

laboratory setting under Task I1. Experiments with the intent of reducing the risks associated with high impact and

droplet drift are being conducted on the aircT'a/i, with fiber suspended droplets under Task III. Initial measurements

are being performed on use of PLIF measurements to describe flame front position. Gas-phase flow dynamics will

be determined by velocity measurements using particle image velocimetry. Measurement of droplet surface and

internal transport will be attempted later in the program. The applicability of liquid phase thermomeu'y in a

burning droplet is being pursued at NASA LeRC and l_equent consultation toward that effort is being provided by

UTRC.

TASK SIGNIFICANCE:

Optical diagnostics offer non-intrusive measurements of either scalars or vector quantities in multipoint

measurements. Experimental droplet combustion data critically tests the combustion theory and provides input for

modelling spray combustion used in combustors.

PROGRESSDUBIN6FY 1994:

Hardware:

An apparatus for performing laser-induced fluorescence measurements of tiber supported burning fuel droplets aboard

the NASA Learjet and KC-135 aircraft facilities was designed and built primarily in 1993 with testing and use in

1994. The rig houses a self-contained miniature nitrogen-pumped dye laser system and two-dimensional intensified

11-333
CCDandunintensifiedCCDimagingsystems.Twotimecodegenerators, twoVCR's,atiming system, and

Macintosh llci computer with image digitization hardware form the data collection/storage system. Droplet

deployment, ignition and synchronization to the timing electronics is accomplished via a unique system of radio

controlled model airplane controls.

Experiments:

During the week of December 13, 1993, a series of tests were performed on the NASA Lewis Learjet aircraft. Two

experiments were attempted during these flights, planar laser-induced fluorescence (PLIF) and particle image

velocimetry (PIV). The PLIF experiments were performed using sodium as the fluorescing species originaung from

sodium seeded methanol droplets. These images provide information on the flame front position for comparison

with theoretical calculations. The PIV experiments utilized 0.9 um silica partilces entrained into the flow ~ 15

seconds prior to ignition. These experiments were less successful as upon ignition, the heat release and

corresponding gas expansion propels the PIV seeds out of the measurement volume.

During the week of April 11, 1994, aircraft experiments were again conducted. Tests were directed at the following:

1. Ignition vs. ignitor stand-off distance for methanol.

2. Radical chemiluminescence with simultaneous visible luminosity images.

3. PLIF images from burning methanol droplets with simultaneous visible

luminosity in NaCI seeded methanol droplets.

4. PLIF images from burning ethanol droplets with simultaneous visible

luminosity in NaCI seeded ethanol.

Results:

Ignition standoff data for the methanol indicated that the ignitor wire needed to be as close as physically possible to

achieve reliable ignition. In contrast, the position of the ignitor needed to be several diameters away from the

droplet surface to achieve reliable ignition in ethanol.

Successful radical chemiluminescence. PLIF and visible flame luminosity images were obtained. Initial analysis

indicates that the broadband visible flame luminosity and radical chemiluminescence agree well in mapping the

flame front position. Comparison between the broadband visible flame luminosity and simultaneous PLIF images

of NaCI seeded burning methanol droplets indicates that the visible luminosity is not a reliable marker of the flame

front position, being dominated by Na chemiluminescence for droplets seeded with NaCI.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 9/92 EXPIRATION: 9/94

PROJECT IDENTIFICATION: 962-22-05-44

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Winter, M. "Laser diagnostics for microgravity droplet studies."

Rent, NV. AIAA Paper 94-0431, January 10-13, 1994.

AIAA 32nd Aerospace Science Meeting and Exhibit.

11-334
II. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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Combustion qf a Polymer (PMMA) Sphere in Microgravity

PRINCIPALINVESTIGATOR:Dr. Jiann C. Yang National Institute of Standards and Technology (NIST)

CO-INVESTIGATORS:

Dr. Anthony Hamins National Institute of Standards and Technology (NIST)

TASK OBJECTIVE:

The Objective is to investigate the combustion characteristics of spherical PMMA particles in reduced gravity.

TASK DESCRIPTION\

Experiments will be conducted to study both supported and unsupported PMMA particles burning in a controlled

environment under microgravity conditions. The test conditions will be room temperature and pressure (25 °C and

1 arm). The ambient oxygen concentration will range from 19% to 70% and the particle size will be 3, 5 and 7

ram. Different ignition methods will also be tested. The diagnostic system will consist of a CCD video camera

and a high speed movie camera. The video and film nnages will be analyzed to provide information on burning

history, flame location, soot formation, burning rate, and other combustion characteristics.

TASK SIGNIFICANCE:

This experunent is the first attempt to study the combustion of a solid fuel sphere under microgravity conditions.

The one-dimensional configuration will simplify the data interpretation and the test results will provide some

fundamental information to solid fuel combustion science.

PROGRESSDURING FY 1994:

Preliminary ignition experiments of PMMA spheres were conducted with different devices. The spheres of 5 mm in

diameter were easily ignited with a small propane torch. However, ignition of the sphere (without preheating) could

not be achieved when a spark ignitor (with an on-time of more than 2 sees) was used. Ignition of solid PMMA

spheres was then further tested. Spark ignition of a PMMA particle coated with a thin layer of ethanol was

unsuccessful. Neither was with a preheated particle. However, ignition was "always achieved using a small torch or a

match. The PI concluded that a micro-torch might be the appropriate means to ignite particles. Therefore, a

micro-torch is being designed for ignition. The system is very similar to a cigarette ignitor using liquid butane.

The fabrication method of PMMA spheres with embedded thermocouples was devised and planned. PMMA powder

will be dissolved in a solvent and an initiator (benzoyl peroxide} will then be added to the solution. The polymer

solution will be cured in an oven into a spherical mold and a thermocouple inserted into the solution. Some

technical problems s011 remain to be solved, e.g. how to avoid bubble formation in the PMMA sphere. A

technique is 'also being tested to accurately embed a thermocouple junction at desired location inside a PMMA

particle. The tirst step is to heat the thermocouple by passing a electric current through it. Then the heated

thermocouple is lowered into a PMMA particle by using a linear positioning stage,

Some experimental equipment were consolidated. A LO-CAM (model 50) was located in-house at NIST. A scanner

capable of digitizing 16 mm films was "also acquired. Imaging software such as SigmaScan/Image is needed.

Dr. J. C. Yang (PI) and Dr. A. Hammins (Co-l) visited NASA Lewis Research Center and toured the microgravity

facilities. They obtained first-hand information on rig construction, test procedures and other related issues through a

series of discussions with people from the Space Experiment Division.

11-335
ll. MSAD Program Tasks -- Ground-based Research Discipline: Combustion Science

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STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 4t98

PROJECT IDENTIFICATION: 962-22-05-63

RESPONSIBLECENTER: LeRC

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II-336
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

Study of Two-Phase Flow and Heat Transfer in Reduced Gravities

PRINCIPALINVESTIGATOR: Dr. Davood Abdollahian S. Levy, Inc.

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective is to conduct two-phase flow instability studies in vertical upllow and downtlow, in both a normal

gravity environment and in low gravity aboard an aircraft, to ascertain the effect of gravity on instability and boiling

mechanisms.

TASK DESCRIPTION:

The approach is to design and build a recirculaung flow boiling loop which would be used aboard an aircraft to test

different two-phase flow instability phenomena and measure the conditions at which critical heat flux occurs.

Specifically, the instability phenomena to be examined are the following: nucleation instability, flow pattern

instability, excursive instability, oscillatory instability, and density wave instability. Testing would consist of

examining the flow stability and critic',d heat flux in normal-gravity vertical upflow and downflow as well as in low

gravity aboard an aircraft.

TASK SIGNIFICANCE:

Two-phase instabilities have been responsible for a multitude of fatal and costly accidents on Earth in the oil.

electric power and nuclear industries. In addition, by understanding critical heat flux better, it may be possible to

improve the cooling of microcircuitry used in the electronic industry, thus improving the capability of that circuitry.

PROGRESSDURING FY 1994:

Design of the electrical and/low systems and the test sections was completed and approved by the NASA COTR.

Construction of the llow loop and test sections was initiated and completed. The data acquisition and control

system software was written and is being debugged. A Lab Windows package is being incorporated.

Two Learjet equipment racks, a high-speed camera body and mount, and a mockup of a SAMS accelerometer were

furnished as government furnished property. The flow loop, camera, data acquisition and control system, and

accelerometer are being incorporated into the racks,

The test sections are mounted to a support structure other than the Leafier racks for normal gravity testing. This

permits vertical upflow and downflow conditions to be examined. Shakedown testing of the flow loop has

commenced.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 3

MS Students: 1

PhD Students: 0

TASK INITIATION: 3/93 EXPIRATION: 3/96

PROJECT IDENTIFICATION: 962-24-05-50

RESPONSIBLECENTER: LeRC

11-337
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Abdollahian. D. and Barez, F. "Study of two-phase flow and heat transfer in reduced gravities." Presented at Second

Microgravity Fluids Conference in Cleveland, OH. June 21-23, 1994.
Colloids & Nucleation

PRINCIPALINVESTIGATOR:Prof. Bruce J. Ackerson Oklahoma State University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

Direct observations will be made of the nucleation and early growth of crystals comprised of

polymethlylmathacrylate (PMMA) "hard" colloid_ spheres in an index matching solvent. Colloidal samples will

be prepared in a particle volume fraction range which exhibits crystals of colloidal particles at equilibrium. These

samples will be shear melted and the subsequent appearance of crystals monitored by direct observations/video

camera recording at the first order Bragg scattering angle.

TASK DESCRIPTION:

1. Apply classical nucleation theory in the limit applicable to hard sphere interactions to compare against data.

Modem analytic (density funcuonalt trod simulation results will be compared with data as appropriate.

2. Establish the practical limiting density supersaturation that can be studied without interterence due to

sedimentation induced convection.

3. Conduct an exploratory investigation of the density or order parameter fluctuations leading to a critical nucleus,

and if possible, characterizethe size and ttme dependent characteristics of these fluctuations.

TASK SIGNIFICANCE:

The experimental observations of nucleation and early growth of crystals comprised of "hard" colloidal spheres will

provide a critical test of classical nucleation theory.

PROGRESSDURING FY 1994:

Work ha,,; been initiated, but to date no substantial pr_gress has been made.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-24-05-78

RESPONSIBLE CENTER: LeRC

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11-339
II. MSAD Program Tasks m Ground-based Research Discipline: Fluid Physics

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Stability Limits and Dynamics of Nonaxisymrnetric Liquid Bridges

PRINCIPALINVESTIGATOR: Prof. lwan D. Alexander University of Alabama, Huntsville

CO-INVESTIGATORS:

Dr. J.M. Perales

Dr. J. Meseguer

Universidad Politecnica de Madrid

Universidad Politecnica de Madrid

TASK OBJECTIVE:

The objectives of the proposed work are:

1. To determine the stability limits of Nonaxisymmetric liquid bridges held between non-coaxially aligned disks.

2. To examine the dynamics of Nonaxisymmetric bridge configurations and Nonaxisymmetric oscillations of

initially axisymmetric bridges.

3. To experimentally investigate the vibration sensitivity of liquid bridges under terrestrial and low gravity

conditions.

TASK DESCRIPTION;

The program is to have simultaneous experimental and theoretical efforts. Experimentally, normal-gravity tests

using the Plateau method will be conducted to study the equilibrium shapes and stability limits of various

orientations of the liquid bridge, and to study the sensitivity of liquid bridges to axial and lateral vibration.

A numerical model will be developed using Picard iterative procedure to study the dynamics of Nonaxisymmetric

bridges subject to g-jitter and the vibration sensitivity of liquid bridges.

TASK SIGNIFICANCE:

Liquid bridge stability is an important factor in determining the stability of molten zones associated with floating

zone crystal growth experiments. Such understanding can help better define the vibration isolation requirements for

in-space processing experiments, and can greatly enhance the chances of obtaining new and better quality

semi-conductor crystals.

PROGRESSDURINGFY 1994:

In FY94, the stability limit of bridges held between coaxial disks was expertmentally studied. The transition from

symmetric to asymmetric configuration was observed, and numerical analyses were conducted to investigate the

effects of gravity orientation on the maximum and minimum volume stability limits. A novel technique for

measuring the force applied to the support disks has been developed and applied to dynamic lateral shearing and

squeezing experiments. A neutral buoyancy tank has been constructed to allow lor vertical and lateral tow frequency

vibration of the support disks, and to allow for independent rotation of the two support disks. In addition, a

theoretical investigation has been conducted to study the effects of vibration on the stability limit of liquid bridges.

The study shows that the bridge may be stabilized or de-stabilized relative to the static stability margin depending on

the nature of the axial vibration.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 12/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-60

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: l

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II-340
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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BIBLIOGRAPHIC CITATIONS FOR FY 1994:

,Iournals

Meseguer. J.. Gonzalez, M..A. and Alexander, J.ID. Dynamic stqability of long axisymmetric bridges. Microgravity

Science and Technology, VII. 234-242 (1994).

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11-341
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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Investigations of Multiple-Layer Convection

PRINCIPALINVESTIGATOR:Prot'. C. D. Andereck Ohio StateUniversity

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The convection patterns that develop in two-layer fluid systems are to be studied. The principal objectives are:

1. To test the predictions of theoretical investigations.

2. To study the interaction of the pattern in one layer with the pattern in the other layer.

3. To determine the role of the geometry of the test cell on the patterns that emerge.

4. To determine the impact of surfactants at the fluid inter/ace on the interface protile and the patterns that form.

TASK DESCRIPTION:

An experimental investigation of natural, buoyancy driven, convection in a system consisting of two superposed

layers of immiscible fluids will be performed. Narrow, pseudo-one-dimensional, test ceils will be constructed with

insulating side walls and conducting top and bottom walls. Temperature control of the horizontal surfaces will be

provided initially by circulating known temperature water next to these surfaces. Shadowgraph visualization

techniques, which are sensitive to index of refraction variations resulting li'om temperature gradients in the fluids,

will be used to determine the flow patterns. This allows for observations of the basic dynamics of competing

instabilities in the two layers. A direct comparison will then be possible between existing general theories of

pattern competition, and experimental results lor a specific system. This will also provide a test for direct

numerical simulations of two fluid layer systems. Further work to be pertbrmed includes studying the deformation

of the interface as a function of control parameter and with the introduction of surfactants. Finally, the geometry of

the cell will be varied. To introduce periodic boundary conditions in one dimension we will construct an annular

cell. Another variation will be to construct a cell with large extent in both horizontal dimensions, thereby freeing

the system to choose more complex competing patterns.

TASK SIGNIFICANCE:

Multiple-layer convection is of interest in geophysical, astrophysical and industrial settings. It is also of

importance as a lundamental pattern forming nonequilibrium system. These experiments will provide a quantitative

test of our theoretical understanding of this fluid dynamical .system. Results on the pattern formation processes

may also be directly relevant, in thin layer limits, to understanding and improving film coating processes.

PROGRESSDURING FY 1994:

In the startup phase of the grant we have built a first version of the test cell and have used shadowgraph imaging to

view the patterns. The cell is a narrow rectangular box, with the top and bottom walls of copper and the side walls

of a single block of machined and polished plexiglass. The shadowgraph system consists of a HeNe laser with a

spatial filter, beam expander and large collimating lens, which produces a reasonably intense parallel beam that

passes through the side of the cell. This is followed on the other side with a screen and video camera lor image

capture and analysis. This has been tested for a single layer of silicone oil. We are now testing various

combinations of silicone oils, mineral oils, and other liquids to find those that provide optimum matches for the

two-layer experiments. A particular problem is matching the viscosity and thermal conductivity in such a way that

the two layers will become unstable to their respective patterns simultaneously. A further criterion is that the fluids

be immiscible, at least roughly so over the time scales of the experiments.

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Our plans lbr the remainder of this year will include performing a.s detailed a study a._ possible of the interaction of

the patterns for different layer depth ratios, particularly those that lead to resonant interactions, and building two

other test ceils. The first will be an improved version of the present rectangular geometry, with better temperature

control and attention to the sidewall conditions. A second cell will be annular in shape, to eliminate the end

boundaries of the cell and allow for patterns that are free of any pinning, driving or forcing effects of the end walls.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-79

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 2
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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Electrokinetic Transport of Heterogeneous Particles m Suspensions

PRINCIPALINVESTIGATOR:Prof. John L. Anderson Carnegie Mellon University

CO-INVESTIGATORS:

S. Garoff Carnegie Mellon University

TASK OBJECTIVE;

There are three objectives to our research program. The first is to complete a hydrodynamic theory lor the motion

of slender colloidal particles in electric fields. The other two objectives involve experimental measurements. The

first of these is to design and develop a microelectrophoresis apparatus and video imaging system that would enable

us to follow the kinematics of colloidal doublets in electric fields. The second experimental objective is a study of

the rotational rates of doublets of latex particles in solutions at different ionic strength.

TASK DESCRIPTION:

1.The electrophoresis of nonunitormly charged slender particles, such as cylinders and prolate spheroids, is analyzed

in terms of existing models for the hydrodynamics of such particles. The basic idea is to apply the Lorentz

reciproc',d theorem of Stokes/low with the concept of electroosmotic "slip velocity" on the surface of the particle to

obtain explicit "algebraic expressions or quadratures for the translational and rotational velocities of the particle of

arbitrary contour shape (straight, curved, helical, etc.). This theory can be directly extended to model the

electrophoresis of uniformly charged slender particles in nonunilorm electric fields.

2. The microelectrophoresis apparatus must permit observation of particle motion in a constant, one dimensional

electric field at field strengths ranging from 0.1 to 50 V/cm. The optical quality of the cell is important. In

•addition, a method for recording and analyzing posi_n/orientation versus time for single particles and aggregates

must be developed. Temperature control to better than +1 °C is desired to avoid complications of convection;

however, in analyzing the rotational motion natural and forced convection resulting from the electrical field is not

too much of a problem. In addition to developing this apparatus, the images must be analyzed in a way to interpret

the data in terms of the existing hydrodynamic models fl)r electrophoretic rotation.

3. Colloidal doublets formed by coagulating two latex particles of different zeta potential (i.e., different surface

charge) rotate when an electric field is applied. Two theoretical models, differing only in the physical picture of the

doublet, are av',dlable for the angular velocity of the doublet as a function of sphere sizes and zeta potentials. We

are collecting data at different solution conditions (pH, ionic strength) for comparison with these two models.

TASK SIGNIFICANCE:

1. Many colloidal systems are not composed of spherical, uniformly charged particles. For example, clays are disks

with edges that differ fi-om the faces, and most inorganic colloids have different crystal planes exposed at the surface

thereby generating a "patchiness" to the charge. Aggregates of particles also create heterogeneous supraparticles that

could result in chains with a distribution of zeta potential along their length. Our theoretical work on

electrophoresis of charged slender particles expands the range of understanding heterogeneous systems.

2. The now classical DLVO theory of the energetics between two colloidal particles in aqueous media predicts two

states of adhesion between two spheres. The t-trst is a "primary minimum" in the potential energy which occurs

when the two spheres essentially touch. The second state of adhesion is in the "secondary minimum" where

electrostatic repulsion balances attraction caused by London dispersion forces; the secondary minimum is

characterized by gap distances of order 4-8 Debye screening lengths. From hydrodynamics we expect that a doublet

in the primary minimum would rotate like a rigid body in an electric Iield, with the more positive sphere rotating

toward the field direction, while in the case of a secondary minimum the apparent doublet rotation occurs with each

11-344
sphererotatingatadifferentangularvelocitytokeepthehydrodynamic torqueon it equ',d to zero. The difference in

rotation rate predicted by theory loT these two cases is a factor of 3. We believe that electrophoretic rotation is a

tool to probe the state of adhesion of colloidal aggregates.

PROGRESSDURIN6FY 1994:

1. The theoretical model for electrophoresis of slender particles has been developed and published. Some remarkable

predictions are made by the theory in the transport of long straight particles in nonuniform electric fields as would

be realized at the entrance of pores in a membrane. These predictions form the basis of an experimental program

that we will initiate soon.

2. The microelectrophoresis apparatus has been developed with video imaging capabilities. A moment analysis has

been developed to interpret orientation versus time data to obtain the fundamental parameters (electrophoretic

rotation, Brownian diffusion coefficient) needed to characterize the heterogeneous colloidal doublets of latex that are

being studied. Data are currently being collected and analyzed.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: ()

PhD Students: 1

TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-24-08-09

NASA CONTRACT No.: NAGS-964

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Anderson, J.L. "Electrophoresis of nonuniformly charged chains."

Society Meeting, Denver. CO, 1993.

Symposium on Electrophoresis. American Chemical

Anderson. J.L. "Electrophoresis of heterogeneous aggregates of colloidal particles." AIAA 32nd Aerospace Sciences

Meeting, Reno. NV, January 10-13, 1994.

Anderson, J.L. "Electrophoresis of heterogeneous colloids: disk and long chains." 8th International Conference on

Surface and Colloid Sciences, Adelaide. South Australia. February. 13-18. 1994.

Anderson. J.L. "Electokinetic transport of heterogeneous particles in suspension." NASA Microgravity Fluid Physics

Conference, Cleveland. OH. June 12-13, 1964.

Anderson, J.L. "Rotation of colloidal particles by electrophoresis." Seminar given at van't Hoff Laboratory, Kruyt

Symposium, Utrecht, The Netherlands, October, 1994.

11-345
Experimental Study of Liquid let Impingement in Microgravity: The Hydraulic lump

PRINCIPALINVESTIGATOR:Prof. C. T. Avedisian Cornell University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The primary objective of this task is to investigate the experimental study of liquid .jet impingement in

microgravity. The proposed experimental study is 'aimed at understanding the effects of gravity on a hydraulic .jump

formed during impingement of a liquid jet on a target plate.

TASK DESCRIPTION:

This study is important in applications which involve cooling of a heated surface by a relatively colder liquid jet

since the heat transfer rate is strongly affected by the velocity {and hence the thickness) of the liquid film spreading

on the surface. The principal investigator plans to examine the effect of gravity on the location of the hydraulic

jump created by an impinging water .jet onto a fiat surface.

TASK SIGNIFICANCE:

This experimental study will test the validity of the theoretical predictions, and provide a first step towards more

detailed studies of beat transfer and phase change processes associated with jet impingement cooling of heated

surfaces in microgravity environments.

PROGRESSDURING FY 1994:

The research to study the fluid mechanics of a circular hydraulic jump (CHJ) formally began on July 1, 1994. The

first task was to make final arrangements for personnel. The original proposal called for graduate student

participation. However, it was later judged that the short duration of the project would be better served by

participation of a more experienced person. Accordingly, a post doctoral associate was hired effective July 1, 1994.

The work underway is centering around designing a chamber to create a laminar CHJ. The apparatus will include a

nozzle to create the jet plate on which the .jet will impinge, circulation pump, fluid containment, and photographic.

Perhaps the most critical aspect of the design will be Ibr the fluid jet. It can be created by either a sharp--edeged

orifice arrangement or by fluid emerging from a tube. The photographic arrangements that is currently being set up

is based on 35 mm photography. Various lighting arrangements will be examined to yield the best contrast and

image clarity.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/95

PROJECT IDENTIFICATION: 962-24-00-34

RESPONSIBLECENTER: LeRC

i i l l II I I i n i ii i iii o i leol I iii i iii i l l oIi iii I iii i ii l ii l i i iii i i l II i i I ii iII I i i i ii i i I l l I III I II I IIiii i i i i i i i i i I II I I I I I ai i i ii i ii aI ii I i II I I l Iii Ill I I i l ii I I III I I I III III II I II I II I i i l l I l II I II I Ill l i i i I I II l l ii I II I ii Ii I I I I I I l I I i i ii I al i i i ii iii I lai II l i i i i l i II l I I I

11-346
Studies on the Response qfl EmuIsions to Externally-hnposed Electric and Velocity Fields:

Electrohydrodynamic Deformation and Interaction of a Pair of Drops

PRINCIPALINVESTIGATOR:Prof. James C. Baygents The University of Arizona

CO-INVESTIGATORS:

H. Stone Harvard University

TASK OBJECTIVE:

The objective of this study of multiphase electrohydrodynamic flows is to determine the electric field-induced

microstructural response of two-phase systems, as well as to develop an improved understanding of the

physicochemical and transport process common to a variety of low-gravity flows; we examine the motion,

deformation, and interaction of pairs of viscous drops owing to an applied electric field.

TASK DESCRIPTION:

The research is a comprehensive numerical and theoretic',d study of several phenomena common to multiphase flows

where electrical fields are used to manipulate the microstructure in the absence of any buoyancy-induced fluid

motions, This class of problems appears in typical materials handling, physicochemical processes (e.g,, emulsion

breaking and drop coalescence) and bioseparations processes (e.g., aqueous two-phase partitioning).

This investigation is designed to use numerical solutions to develop an improved quantitative understanding of the

effect of electric fields on typical two-drop (parr) interactions that lead toward coalescence. Cases will be studied

where the potential distribution is influenced by conduction processes in the limxt where viscous effects dominate

the hydrodynamics. Both the effects of uniform and simple nonuniform (imposed) fields will be studied. The

"leaky" dielectric model and the Stokes equations will be employed to describe the constitutive behavior of the

dielectric media. The numerical calculations will use established integral equation methods for solving this class of

time-dependent free boundary problems.

TASK SIGNIFICANCE:

The systematic study will lead to a quantitative description and understanding of electrically-driven low-gravity fluid

motion, particularly as these flows pertain to the manipulation and positioning of drops and bubbles wxth electric

fields. Such flows are significant for several reasons. First, in the absence of the usual gravitational forces, electric

fields can be used to effect phase separation processes that are controlled by drop coalescence (e.g. emulsion

breaking). Second, electric fields have long been envisioned ms a tool for containerless processing of materials,

inasmuch as the fields can be used to manipulate fluid interfaces, such a_sthose of a drop surface, and as a means to

levitate fluid globules against weak gravitational fields.

PROGRESS DURING FY 1994:

We have successfully implemented and tested numerical solutions to two problems. The first is the axisymmetric

electrohydrodynamic detormauon and interaction of equal-sized drops subject to the imposition of a uniform electric

field. A summary of this work was submitted to the Proceedings of the Second Microgravity Fluid Physics

Conference, held in Cleveland, OH, July 1994. A complete exposition of the work is to be submitted tbr

publication at the end of CY94.

The second problem solved is the electrohydrodynamic deformation and translation of a single drop in a nonuniform

electric field. Here numerical results have compared favorably to limiting analytical cases for the drop translation,

which were worked out as part of this project to provide benchmarks for the numerical studies.

11-347
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 3/93 EXPIRATION: 3/96

BS Students: 0 BS Degrees: O PROJECT IDENTIFICATION: 962-24-08-13

MS Students: 0 MS Degrees: l NASA CONTRACTNO.: NAG8-948

PhD Students: 1 PhD Degrees: 0 RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Baygents. J,C. "Electrohydrodynamic deformation and interaction of a pair of emulsion drops." Second Microgravity

Fluid Physics Conference. NASA Lewis Research Center, Cleveland, OH. June 21-23, 1994.

iII i II III IJa I ! I l I |1111 ! I I I | I I I i Ill I ! I I I I I I I Ili III | i I ! i I |eill Iil III ! Ill II I I i Iil i llli I I I !il I | I I ! i I I I II | i I | I I I I I I aI I ! aIll I i aII I i| I I ell us Ill ill Ill I I IIll Ill I | I I | II I aI i iie I | ei || i ill i i is ii I ill i i i ni I ill eIll i i | lU I1| Jllia I Jl I I ai i i i i ea II I aeai i i |11 ei i i i i

11-348
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Marangoni Effects in Boiling of Binary Fluid Mixtures Under Microgravity

PRINCIPALINVESTIGATOR: Prof. Van P. Carey University of Calilk_rnia, Berkeley

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

Recent eflorts to more fully optimize performance of power, refrigeration and thermal control systems have lead

some developers to consider the use of binary working fluids. Vaporization of the working fluid is often a critical

element in the performance of such systems. However, transport phenomena associated with vaporization of binary

liquid mixtures is still not well understood. The main objective of this project is to separate and explore the roles

of buoyancy and Marangoni eflects in binary liquid mixture boiling under simulated low gravity conditions. The

research will also aim to find coolant mixtures that are parucularly well suited tot use in a variety of applications

including spacecraft thermal control.

TASK DESCRIPTION:

This project consist of a series of experimental studies of nucleate boiling of a variety of binary mixtures. The

experiments will include both 1-g and low-g data of boiling curve and critical heat flux. Testing the boiling

performance of the heating surface in different orientations will establish whether the presence of Marangoni effects

reduces the sensitivity of the system to the direction of the gravity vector. The least sensitive mixtures will then

become the locus of tests under low gravity conditions (via NASA LeRC drop towers or low-g aircraft).

TASK SIGNIFICANCE:

The experimental database tot boiling of binary fluid mixtures will help to clarify the individual contributions of

gravity and Marangoni effects on the heat transfer from the surface and the critical heat flux transition. It will "also

help to develop a capability to model these effects with reasonable accuracy to improve the designs of thermal

systems.

PROGRESSDURINGFY 1994:

During this reporting period, the lollowing have been accomplished:

1. A Learjet rack was received from NASA LeRC. The rack is on loan to UC Berkely to be used as the support

frame for the experiment.

2. Component assembly is currenly in process.

3. Started system design and installationinto the support frame.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6194 EXPIRATION: 6196

PROJECT IDENTIFICATION: 962-24-00-81

RESPONSIBLECENTER: LeRC

11-349
MarangoniInstability Induced Convection in Evaporating Liquid Droplets

PRINCIPALINVESTIGATOR: Dr. An-Ti Chai NASA Lewis Research Center (LeRC)

CO-INVESTIGATORS:

Prof. V.R. Arpaci University of Michigan

TASK OBJECTIVE:

The objectives ot the proposed effort are: {1) to study and to characterize the Marangoni instability phenomena in

the near ideal configuration of an evaporating droplet in microgravity, and (2) to establish the effect of the induced

convection on the droplet evaporation rate.

TASK DESCRIPTION:

Specifically, the purpose is to study the Marangoni instability and thermocapillary convections in an evaporating

liquid drop in the Fluids Experiment System (FES) developed tor flight on Space Shuttle missions. When a liquid

drop undergoes evaporation, its surface temperature decreases. If the droplet is free floating in a microgravity

environment, the heat transfer process inside the droplet is "conduction controlled." As the process continues, a

radial temperature gradient builds up at the flee surface until the critical Marangoni number is exceeded. Then the

onset of instability induces thermocapillary convective flows that, in turn, speed up the evaporation. The

convective flow will subside when the interior of the droplet reaches a certain equilibrium temperature, and the

process will return to the "diffusion controlled" mode.

TASK SIGNIFICANCE:

When the proposed experiments are successfully completed, the unique data set, which will be collected under near

ideal conditions, should by itsell constitute a significant contribution to our knowledge of droplet evaporation. The

significance and influence of the proposed project go tar beyond any unique experimental data set. With the

anticipated data set, it will be possible to quantitatively evaluate the well known Maxweii's theory of droplet

evaporation. Additionally, it will be possible to establish that thermocapillary instability induced convection inside

a droplet can affect its evaporation process. It is our intention to use this information to pursue the development of

a complete and comprehensive theory of droplet evaporation.

The value of a more comprehensive and complete theory cannot be overstated. Having a solid theoretical basis,

numerical computation can be devised along with skillful scaling techniques to explore cases where direct

experimentation is not feasible. The influence of the proposed work is expected to be far reaching in this regard.

PROGRESSDURINGFY 1994:

Most feasibility issues have been demonstrated experimentally. An analytical and numerical scheme has been

applied to model the quasi-static thin shell configuration. Qualitative agreement has been obtmned between this

model and dimensional analyses.

Our recent analytical effort was to pursue the transient nature of the Marangoni instability problem encountered in

an evaporating droplet. As a result, we formally introduced a new fundamental dimensionless number,

I-L~ Ma/( l+Pr 4)

for thermocapiilary driven flows. Here Ma and Pr are respectively the usual Marangoni and Prandtl numbers. The

significance of this number for past Marangoni instabilities is demonstrated in terms of a projection method

involving the Godunov discretization for convective terms. Particular eflbrt has been made to compare results from

the new approach with data available in the literature. However, direct simulation of space-wise distributed

problems requires considerable computation time at higher transition. We have begun the exploration of the theory

of nonlinear dynamic systems (chaos) which appears to be an appropriate and effective approach.

r_¢____r_f_______l_

II-350
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 4/93 EXPIRATION: 4/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-00-65

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Arpaci, V.S.. Kou, SH., and Chai, A.T. Chaotics of thermocapillary driven flow past Marangoni instability. Two Fluid

Flows-With or Without Phase Change. AMD-vol.[84. (1994).

Proceedings

Arpaci, V.S., Evren-Selamet. E., amd Chai, A.T. "Thermocapillary driven flows past Marangoni instability." AIAA 32nd

Aerospace Sciences Meeting. Reno, NV. January 21-23. 1994.

Chai, A.T. and Arpaci, V.S. "A realistic model of evaporation for a liquid droplet." Proceedings of the Second

Microgravity Fluid Physics Conference. Cleveland. OH, June 21-23. 1994.

11-351
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

o t *, I I I | * !,* * iii * | * Q* m| i * * s ¢ hi * | I*. * | I * i|, |i a I * * llll *, *s a, * g * t *, I i i, i i. I, | | * | * I,, ! s I i D| e, | s s i | i * | g I| i | I | i I i i ¢ I * |; i| Illl I * I, | | t * o | |s I I, |, ¢ i | ¢ I 11 | |t * H | pi, 0 I* i * * | I* iii * ! i, i, * | |! * ! * i,,,, |! I | |,, * ¢ | |,, Ii * |! J I I, I i, ,|,, i! ol |, Ii * *, ! ,I | 11, i, i i *, t, * t, i

Rewetting of Monogroove Heat Pipe in Space Station Radiators

PRINCIPALINVESTIGATOR:Prof. S. H. Chart University of Wisconsin, Milwaukee

CO-iNVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The general objective of the program is to investigate the physics of rewetting of heated, grooved flat plates in a

microgravity environment.

Specific objectives of the program are to add to the fundamental understanding or" the physics of rewetting/dryout

fronts; to better quantity the conditions under which rewetting occurs; and to obtain more accurate predictions of the

rewetting velocity for a range of parameters.

TASK DESCRIPTION:

The program is composed of both experimental and theoretical investigations. For the experimental investigation a

grooved fiat plate apparatus will be designed and constructed. Liquid will be introduced on one side of the plate to

flow along the grooved surface; the other side of the plate will be electrically heated. This apparatus will be

operated both on the ground and aboard a microgmvity aircraft.

Data trom these experiments will consist of temperature measurements in the liquid film and the heated plate.

Advancing wetting front (rewetting), receding wetting lYont (tryout), and stationary wetting front cases will be

examined.

The theoretical analysis will be made by applying experimental data on rewetting velocity and temperatures to

analytical processes developed for predicting rewetting velocities on overheated nuclear fuel rods.

TASK SIGNIFICANCE:

Understanding the dryout and rewetting characteristics of grooved surfaces is important in predicting behavior of

monogroove heat pipe designs proposed for the space station.

PROGRESSDURINGFY 1994:

Several aspects of experimental apparatus have been modified and improved and laboratory testing has "also been

undertaken. They are as follows:

1. A new liquid delivery system has been designed to eliminate reliance on gravity to drive flow to the test

section. The delivery system was successfully tested to show that the rewetting speed is independent of the liquid

supply velocity in both plate orientations, the grooved surface upward-facing and downward-facing positions.

2, A video recording system capable of recording and playing back high resolution pictures frame-by-frame

was installed to measure rewetting front locations.

3. A lighting mechanism was installed to synchronize the computer data acquisition time with the video

time.

4, The surface temperature measured by two spring-loaded traversing thermocouple probes was tested and

found in agreement with the embedded thermocouple.

5. Rewetting experiments were conducted with the plates preheated to various initial temperatures and with

plates in the face up and the/'ace down orientations. The heating was provided by a new heater (with a new

controller) installed at the end of the plate.

II-352
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

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The following theoreucal works have _dso been undertaken:

1. Hydrodynamically controlled and conduction controlled rewetting models were proposed respectively for the

plate temperature lower and higher them the wet front temperature.

2. Numerically exact solutions for the rewetting of a plate heated from one end was obtained lor various

conditions.

3. Approximate analytical solutions were also obtained for the prediction of the wetting speed on l]nite,

initially-isothermal plates subject to heating from the end of the plate. The solution was found in good agreement

with the numerical solution.

STUDENTSFUNDEDUNDER RESEARCH:

BS Students: 1

MS Students: 2

PhD Students: 0

TASK INITIATION: 12/92 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-00-54

NASACONTRACTNO.: NAG-1381

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Presentations

Chan. S.H. "Experimental and theoretical studies of rewetting of unheated/heated grooved plates." Presented at and to

appear in the proceedings of the Second Microgravity Fluid Physics Conference. 21-23 June 1994.

, ! i i i iiI i ! I I | I i | i ! I i ii i i I I I i i i i i iI I Iii i i i ! 111 !i i i I i ii i i ! i ill iii i ! I I i ii i i iii i illl I Lll|l I I| III I II I llllllll I|1 IS I III I IS |I I III III III I IIII IIIll I | 11 ILII I III I I I II I l! I I I fll I I i! I I I I | I III I ! II I III I I I II III I I LII II IlI I I lll I llll fll fl I I II I II I I I I I I, I ! I II I I, I I Ill

11-353
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

ainaooInon_oolaonaoo_ao|_oIioonaon|on_o_no_on_onaoIao_aooa_oIooI_o_ao_ao|i_nae_!oo_oIo_ooaon|oo_ot a|lloigollolooDIooooo|llouooloolo!ll|loo! jD_onIiHoMonoo_;ooio_|_o_tooo|oi_oHo_oooioIio_iao|!_H|_oo|oo|o_|H_*_o|a_oaoooo_oo

Marangoni and Double-Diffusive Convection in a Fluid Layer Under Microgravity

PRINCIPAL INVESTIGATOR:Prof. Chuan F. Chen University of Arizona

CO-INVESTIGATORS:

C. Chan University of Arizona

TASK OBJECTIVE:

To study the onset and the subsequent convection in a fluid layer subjected to Marangoni and double-diffusive

instabilities, including the effects of cross diffusion and gravity modulation.

TASK DESCRIPTION"

A coordinated research effort in ground-based experiments, stability analysis, numerical simulation, and a design

sensitivity study is to be conducted. Experimentally, the effect of gravity modulation on the onset and subsequent

convection in singly and doubly diffusive layers will be studied with improved experimental techniques.

Theoretically, stability analyses of Marangoni double-diffusive instability will be conducted, and a numerical

simulation using boundary element method will be carried out to examine the interaction of finger convection with

Marangoni convection, and to test the design sensitivity to optimize the flight experiment.

TASK SIGNIFICANCE:

The results of this study will enable the design of an apparatus for crystal growing and for casting in a space

environment. In addition it will offer an improved understanding of materials processing, which will enhance the

chances of obtaining new and better quality crystals/or the semi-conductor industry and for the bio-medical industry.

This study can also provide an improved understanding of the interaction of surface tension forces and double

diffusive buoyancy lorces which would lead to the improvement of manufacturing processes on Earth.

PROGRESSDURING FY1994:

An experunental and theoretical investigation of the interactions between Marangoni and double-diffusive

instabilities has been completed in FY94. The experiments were conducted in a rectangular tank with dimensions of

25 cm in length, 13 cm in width, and 5 cm in height. A stable solute (NaCI) stratification was l_rst established in

the tank, and then a vertical temperature gradient was imposed. A series of stability experiments was conducted tor

a layer with an initial top concentration of 2 wt% and different concentration gradients. The stability map shows

that in the rigid-free case, the early Marangoni instability at the top region reduces significantly the critical Rayleigh

number for the onset of double-diffusive convection. The results of the linear stability analysis, which takes into

account both surface tension and double-diffusive effects, are in general agreement with the experimental

observation. Results from this stability analysis show that even at 10 a go, where go is the gravity level at sea

level, the double-diffusive effect is of equal importance as the Marangoni effect.

The effect of gravity modulation on Benard convection was also experimentally studied with compressed air as the

working fluid. The test apparatus was mounted on a shaker, which was capable of oscillating up to 2.5 Hz at a

fixed amplitude of 10 cm. A series of experiments was conducted, and the results demonstrated convincingly the

stabilization effect of gravity modulation on Benard instability. In addition, a transient conduction-convection

equation solver has been developed using the Boundary Element Method. This numerical code has been validated

and will be applied to study the Marangoni and double-diffusive convection in a fluid layer under microgravity

conditions.

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11-354
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 12/95

BS Students: 0 PROJECT iDENTIFICATION: 962-24-00-5]

MS Students: 0 RESPONSIBLE OENTER: LeRC

PhD Students: 3

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Chen. C.F.. Chen, C.C. Effects of surface tension on the stability of a binary fluid layer under reduced gravity. Phys.

Fluids. A 6, 1482-1490 (1994).

Presentations

Chen, C.F. "Effects of surface tension on the stability of a binary fluid layer under reduced gravity." AGU Chapman

Conference on Double-Diffusive Convedtion. Scottsdale. Arizona. November 3-6, 1993.

Chen, C.F. "Solid fraction distribution in a growing mushy layer by computed tomography." 46th Annual Meeting of

APS-DFD. Albuquerque, New Mexico, November 21-23. 1993.

Choi, C.Y. and Chen. C.F. "The effect of gravity modulation on convective stability." 10th Arizona Fluid Mechanics

Conference. Scottsdale, Arizona. February 25-26, 1994.

Tanny, J. and Chen. C.F. "Experiments on the effect of a free surface on convective instability in a double-diffusive

layer." lOth Arizona Fluid Mechanics Conference, Scottsdale. Arizona. February 25-26. 1994.

11-355
Transport Phenomena in Stratified Flow in the Presence and Absence of Gravity

PRINCIPALINVESTIGATOR: Prof, Norman Chigier Carnegie Mellon University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The strategy of this study is:

1. To separate the effects of molecular and turbulent diffusion from gravitational forces during the mixing of two

shear layers.

2. To identify the relevant and characteristic non-dimensional parameters that govern the physical interaction

between fluid layers in the range of the proposed experimental conditions.

3. To examine the interaction between buoyant plumes and stratified shear layers, and to study the rates of

entertainment into buoyant plumes and stratified shear layers.

4. To study the effects of injecting solid and liquid particles into fluid streams under stable and unstable stratified

shear flow conditions.

5. To identify potential instrumentation that could distinguish between molecular and turbulent diffusion in the

presence and absence of gravity.

TASK DESCRIPTION:

1. Conduct detailed measurements in turbulent mixing layer with velocity and density gradients.

2. Conduct a scoping on the interaction of buoyant heated jets and plumes interacting with stable and unstable

stratified shear layers.

3. Develop scaling laws and similarity criteria/or comparison with measurements made in the "main" and

"reduced" scale experiments.

TASK SIGNIFICANCE:

To use the reduced gravity environment to improve the understanding of the fundamental physical processes of

mixing between layers of fluids of different densities and velocities. The following are a few matters that are

important to this research project:

1. To understand the process of dispersion of pollutants in a highly stable stratosphere and in outer space.

2. To understand the effect of dispersion of pollutants emitted from a space craft at high altitudes.

These results could be used to find the means of controlling or at least reducing pollutions of the alrnosphere and

the oceans where stratified flows prevail.

PROGRESSDURINGFY 1994:

Significant progress has been made in 1994. The design and construction of the flow facility tor l-g experiments

has been completed. A wind tunnel with two separately heated air flows, separated by an insulating splitter plate,

has been designed, constructed, and tested. The exit velocity and turbulence prot'des have been measured by LDV,

and temperature prot-fles have been measured by thermocouples. Nearly unitbrm velocity profiles at the exits have

I1-356
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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been achieved. Heat transfer across the splitter plate results in therm_ boun "dary layers inside the wind tunnel that

distort the exit temperature profile. The measured turbulence structure, 127 ram downstream of the nozzle exit, is

close to isotropic, and the use of a special turbulence management seclaon, suggested by Dr. Nasser Rashidnia of

LeRC, resulted in the successful flow quality downstream in the flow facility.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 6/93 EXPIRATION: 6/96

BS Students: l PROJECT IDENTIFICATION: 962-24-00-71

MS Students: 0 RESPONSIBLE CENTER: LcRC

PhD Students: l

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

N.Chigier, M. Xu, D. Squarer. and N. Rashidnia "Transport phenomena in stratified multi-fluid flow in the presence and

absence of gravity." Presented at the 2nd Microgravity Fluid Physics Conference. NASA LeRC, Cleveland. OH. June

21-23, 1994, (NASA Conference Publication 3276. pp. 273-278, 1994).

I1-357
I1. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Bubble Dynamics, Two-Phase Flow, and Boiling Heat Transfer in Microgravity

PRINCIPALINVESTIGATOR: Prof. Jacob N. Chung Washington State University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The main objective is to study the effects of external/tree fields on the nucleation, two-phase bubble dynamics and

boiling transport in microgravity. The proposed research seeks to increase our understanding on bubble nucleation

and growth on the heater surface, bubble removal from the heater surface by an electric field, an acoustic field or a

velocity shear resulting from the relative fluid motion with respect to the surface, and bubble dynamics and heat and

mass transport in boiling liquids.

TASK DESCRIPTION:

In the experimental portion of the work, visualizations with laser sheet and high-speed photography and heat

transfer measurements will be performed in a drop tower at Washington State University and on board a Lea_et at

NASA Lewis Research Center. The visualization photographs will be "analyzed by a digital image analysis system.

Also, boiling curves will be developed based on measurements of heat fluxes and surface superheats for various

system conditions. Special attention will be focused on the critical heat flux and Leidenfrost point. Specifically,

the effects of bulk convective motion will be determined. Quantitative assessment of the effects of impurities and

surfactants on the boiling heat transfer rates will also be included. Analytical and numerical modeling will

compliment the experiments. Perturbation and asymptotic techniques will be applied for low Reynolds number

bubble dynamics, linearized bubble stability analysis, and small oscillation of bubbles in microgravity to account

for small disturbances and g-jitter,

TASK SIGNIFICANCE:

The proposed research seeks to:

1. Increase our understanding of bubble nucleation and growth on the heater surface.

2. Bubble removal Ii'om the heater surface by an electric field, an acoustic field or a velocity shear resulting tiom

the relative fluid motion with respect to the surface.

3. Bubble dynamics and heat and mass transport in boiling liquids.

Future spacecraft power systems are likely to have greater power generation and dissipation requirements due to

proposed longer space missions and more intensive space activities. Without suffering from weight penalties,

two-phase boiling systems are being considered for a wide range of future space applications such as thermal

control, propulsion, power generation, and thermal management. The boiling system has the potential advantage of

being able to transfer a large amount of energy over a relatively narrow temperature range with a small weight

requirements. For example, two-phase systems were once baselined for the space station. However, the

thermo-fluid dynamics of two-phase systems in microgravity encompasses a wide range of complex phenomena that

were not understood sufficiently for engineering design to proceed.

PROGRESSDURINGFY1994:

An old elevator shaft at Washington State University has been transtormed into a 2.l-Second Drop Tower.

Numerous successful drops have been conducted. This drop tower uses an air bag to decelerate the test package.

The drop tower is fully operational.

11-358
Both the forced convection microgravity boiling apparatus and the electrostatic microgravity boiling apparatus have

been built and tested in the laboratory using the 0.6 second tower. Gold film heaters have been successfull/built

and tested. To reduce cost the substrate material is polycarbonate instead of quartz. The heaters use a 400 Angstrom

gold surface with a power output of 7W/cm z. Results indicate that when the heat flux is relatively low and the

subcooling remains relatively high the heat transfer is enhanced in microgravity. At high heat flux levels dryout

occurs in microgravity. The result_s are in good agreement with Merte, et al. Similar tests are planed using the

2.1-Second Drop Tower.

The pool and flow boiling apparatus for the 2.1-Second Drop Tower has been designed and built. Currently

calibration and 1-g tests are being conducted, low gravity tests are planned for1995.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 12/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-00-59

MS Students: 2 MS Degrees: 1 RESPONSIBLECENTER: LeRC

PhD Students: 1 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Snyder, T.J.. Sitter, J.S., Chung, J.N. "Maiden drops of WSU 2.1 second drop tower with airbag deceleration system".

submitted to International Journal of Applied Microgravity Technology, (1994).

Wang, T.C., Snyder, T.J., Chung, J.N. "Transient effects of microgravity on pool and low velocity flow boiling heat

transfer". Submitted to Int. J. Heat and Mass Transfer. (1994).

i i i ! i I ! I el Ie I II i eI I I I e! i | i Ie i ii I i I i i ! I i ! i !I I II I i i eI i l I Il l i! ! i! i i i I i i ! ii ! i l i i i ! i ! I lei BeI I III el I eel eI I i pl oIlll l ill III ! eli $lI Ill I I ||1 | I I eI I I ! I II! I $I lll I ! I! I I II | II l I l eI I! III I II I I I eI ! ! ! ! I Ii I II I i i i oi i ! | i I ! i i i i i I|! I eI I ! |! I I i111 ii Ii i I i i i i ei i i i I Ii ii ei i ! i

11-359
II. MSAD Program Tasks -- Ground-based Research Disc/pline: Fluid Physics

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Reactive Fluids Experiment: Chemical Vapor Deposition

PRINCIPAL INVESTIGATOR:Dr. Ivan O. Clark NASA Langley Research Center (LaRC)

CO-INVESTIGATORS:

£.V. Flyer

E. J. Johnson

Lockheed Engineering & Sciences Co.

Lockheed Engineering & Sciences Co.

TASK OBJECTIVE:

The research will develop a series of ground-based experimental investigations of the fluid dynamics of chemical

vapor deposition (CVD) which will lead to an enhanced understanding of the basic sciences underlying reactive fluid

interactions. It will form the basis for a proposal to pertorm a series of flight experiments necessary to more

fully elucidate these scientific principles. This program will use past experience in chemical vapor deposition,

non-isothermal flow measurements, numerical modeling of reactive fluid dynamics, and development of

instrumentation to carry out the research.

TASK DESCRIPTION:

A combined numerical and experimental approach is being used to investigate the CVD process. The experimental

approach combines growth of semiconductor materials, the deposition of a model material, and the measurement of

the gas flow velocities in the CVD reactor using laser velocimetry. The numerical approach models each of the

experimental approaches and uses the experimental results for validation.

TASK SIGNIFICANCE:

CVD is an extremely important industrial process. It is widely used not only for the production of semiconductor

and insulating materials, but also for optical coatings, wear- and corrosion-resistant coatings, paint pigments, and

the production of drawing stock lot optical fibers. In addition to the economic importance of these application areas

lot terrestrial research and manufacturing, they also represent key manufacturing capabilities for future

extraterrestrial development. Each of these CVD applications takes place in reactors which have been developed

through decades of empiricai trial and error. Engineering design capabilities have been limited by the extreme

difficulty, under Earth-gravity (lg), of separating the fluid dynamic effects of externally forced convection, buoyant

thermal convection, buoyant solutal convection, and internally forced convection due to volume changes arising

from both thermal and chemical effects. This research seeks to improve the ability to apply engineering design

techniques to this economically important area.

PROGRESSDURINGFY 1994:

The numerical modeling of InP in three spatial dimensions has been refined with good results. Model/experiment

agreement is best when the experimental films are thick. InP film porosity has proven to be a problem on the

large-area amorphous substrates. Additional growths are being performed with GaAs and InP substrates to examine

substrate effects on measured growth rates.

Laser velocimetry (LV) measurements of the flow velocities in a replica CVD reactor, which duplicates the

geometry used for the InP growths, is in progress. The transition from supply manifold to reactor inlet has proven

to have a significant effect on reactor flows. Numerical modeling of this reactor geometry has been expanded to

include the entry region as well as the effects of thermal gradients on the trajectories of tracer particles used/or the

LV measurements.

11-360
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: ll/90 EXPIRATION: 11/94

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-06-03

MS Students: 0 MS Degrees: 0 RESPONSIBLE CENTER: LaRC

PhD Students: 2 PhD Degrees: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Black, L.R., Johnson. E.J., Hyer, P,V., Culotta. P.W., and Clark, 1.O, "An improved 3-D numerical model of InP MOCVD

with comparison to growth and laser velocimetry experiments." Proceedings of Fluent Inc. 1993 Users' Group Sleeting,

Burlington, VT, October 5-7, 1993.

1I-3 61
II. MSAD Program Tasks m Ground-based Research Discipline: Fluid Physics

_ 11* I _ ! | I ! I I! I J ! |! II | | I * I * wI * ¢ ¢ I *| * ! | * ! | I, I ! II I! * I I * I ! * I I * I! * ! I I | M* | * * | ! I* m| * | I * I I I ! * I ! I Is H t I! I | I * H * I I* ! I| * i I I | I 0 I! I | I! i J | | I ! * i | * I MI ¢I I H * I _ I ! I g I iii i! | i i * I J I I I * II * I J * ! i | * i | ill * _ I I* I * a I M| I a | J I |6 * ¢ * mI * I I, I I J ¢ I !| II I I i I ! ! ! * ** iI * t I s _ tl _ * | | _ ¢|* * |

Microgravity Particle Dynamics

PRINCIPALINVESTIGATOR:Dr. Ivan O. Clark NASA Langley Research Center (LaRC)

CO-INVESTIGATORS:

E.J. Johnson

J.F. Meyers

S.O. Kjelgaard

Lockheed Engineering & Sciences Co.

NASA LaRC/RTG/FIdMD/NDB

NASA LaRC/RTG/FldMD/EMB

TASK OBJECTIVE:

The objective of this research is to develop the apparatus, numerical models, and practices for enhancing the

knowledge of particle transport in laminar fluid flows. Specil-_cally, an enhanced understanding of the roles of

thermophoresis (thermal gradient) and Saffman (particle crossing of velocity gradient) effects on particle transport is

sought. The proposed research also seeks to identify the critical parameters and instrumentation requirements for

subsequent microgravity experiments.

TASK DESCRIPTION:

The technical approach is a coordinated numerical and experimental investigation using geometries selected to

maximize the scientific return of the research. Gravitational effects in the experimental investigation are addressed

through the use of multiple orientations, relative to gravity, of the test chambers. The first step in this

investigation is a parametric study to determine the order of magnitude of the competing effects for candidate test

chamber geometries. These complex interacting effects include gravity, buoyancy, inertia, viscous drag, particle

rotation, electrostatic charges, as well as thermal and velocity gradients. The initial parametric study will ensure a

maximum scientific return from the selected geometry. Experimental studies will use the laser velocimetry (LV)

and flow visualization systems developed for chemical vapor deposition reactor characterization at Langley Research

Center (LaRC). Additional LV and other aerodynamic instrumentation systems are available to this research at

LaRC if needed.

TASK SIGNIFICANCE:

The proposed research will result in: (1) definition of the requirements and the potential for follow-on flight

experiments in transport phenomena, (2) an enhanced understanding of particle transport phenomena in thermal and

velocity gradients, and (3) fluid dynamic correction factors for parncle-based flow instrumentation for a range of

thermophoresis and Saffman environments. The results of this research will be immediately applicable in both

unigravity and microgravity for applications such as validation of particle transport theories; correction of wind

tunnel research data; and design refinements for chemical vapor deposition reactors, particulate combustors, and

clean rooms. In addition, experimental size constraints for microgravity experiments dictate that velocity gradients

will exist in laminar flow flight experiments. Hence, Saffman effects will be present to some extent in all

microgravity laminar flow experiments with particles.

PROGRESSDURING FY 1994:

Steady-state numerical studies of thermophoretic flow patterns have begun. Several shortcomings of the

thermophoresis algorithm used in FLUENT have been identified and an improved algorithm has been implemented.

Parametric studies of velocity, length, time, thermal gradient magnitude and velocity gradient magnitude likely to be

involved in gas-solid multiphase flight experiments have been assessed for 1-100 micrometer particles. The results

of this parametric study indicate that flight experiment regimes are both achievable and useful.

A database has been established of particle dynamics research and particle-based instrumentation which will ensure

currency of ground and flight experiments associated with this research as well as provide a valuable reference tool

for other researchers in this area.

_u_n_I_i_*D_D_*_*_u*_*_I_u_*_¢_uu_j_m_n*_u_B_*_I*Da*_*_u1I_*_n*u_*_*_*_*_eD_*_¢_I_I*_¢_4_m_*n_I_I_*_*_¢_¢_*_*_i*n_

11-362
II. MSADProgramTasksm Ground-based Research Discipline: Fluid Physics

, i i, III I! i i i I I i I I i, | I Ii i ioI I I; ei | i I ei i ! ! tIIi i I i i at I I ! i I I Ii i, i, DI i, _i I I I J_I I I I I _i ill i; oJ i, i i i i i i i ieI I i ! i i i ill, J_ ii i Di i ! t i ! I i i i io ii i oi I oI t i i i i I | i I I I iJ iI oI I | I i I I I I I I II II I | I i i I I J i i I I I I PI II i i i ! i i ! i I ! I Im I ii i 1oI; i i t | I iI o II I I I I oi | I I I I oi i I, I IJ I! | | i i i i, I

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 11/92 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-24-06-04

RESPONSIBLECENTER: LaRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Clark, I.O. and Johnson, E.J. "Particle experiments in thermal and velocity gradients." Proceedings of the 2nd

Microgravity Fluid Physics Conference. Cleveland. OH, June 21-23. 1994.

11-363
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

* i i o ! a * |i a I i | o I i I i I t I Io ii J o * a I | I o I I o | ! | o I ! t| ! o i I t | i o; I It i io o ii i i i _ n I o n a i i I| t i i o i i o n i o oil t Illl* I I a n I | |I | II ! | I OI I I OIo o I J | I ! J I a Oo ! g * It OI I O| I t ! n o o I I * | I io I I* i I I n I I I I J I Ia o II t I a =I I OI I Oo to o I OOII o I Uo II o I011 o o t t 01 oo o o 0 _ 0 0 o o I I O01 * | I 011 | o I I O01 *I I It | I I | I | o I

Studies of Freely Suspended Liquid Crystal Bubbles

PRINCIPALINVESTIGATOR: Prof. Noel A. Clark University of Colorado, Boulder

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The proposed research will develop techniques necessary for the study of levitated liquid crystal bubbles. These

techniques will be used in a series of expertments which will seek to study fluid deformation under circumstances of

static and dynamic compression. In addition, bubble shape when coupled with a structure, and gas permiability

studies will be performed.

TASK DESCRIPTION:

These experimental studies require technique developments beyond those which have been used tor the study of

planar films in 1G. Among the more important ones are (1) a method for inflation, levitation, positional

stabilization, of the bubble. (2) transmission video microscopy to monitor bubble shape and polarized reflection

video rrucroscopy to probe the local orientation, and (3) methods to change ambient gas pressure while maintaining

bubble position.

TASK SIGNIFICANCE:

Ultra thin freely suspended liquid crystal films are structures of fundamental interest in condensed matter physics.

By eventually conducting this research in microgravity, microscopic forces and stresses on bubbles can be observed

in conditions which will accurately simulate two dimensions. Knowledge of thin film structures is necessary to a

complete understanding of membrane phenomena, transport processes, fabrication of thin film materials, and other

materials related fields.

PROGRESSDURING FY 1994:

This new grant was funded on May 16, 1994. The research associate is in the process of setting up the laboratory

apparatus necessary for developing and testing the levitation device and procuring the equipment needed for analysis.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 4/94 EXPIRATION: 3/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-82

MS Students: 0 NASA CONTRACT NO.:NAG3-1600

PhD Students: 2 RESPONSIBLECENTER: LeRC

i I ao |i ooont oI t oo| ooI t ! ii I t t ! anoaI t ooI t I I oI nlooo*aI It. I oI | aot nat |I oI nonoot oot ot !o! I t ! oI t | I t o|uoI I o! aoI uI ogot !11t I I ot III ot I nloI Ino| oI oo n_II ot ! ! I I o| ot mI t I ooooo! oto ! I t I I oI =II ot | I t ! t ouI I unlIt | ! ! IoI I | t oo|tql I oo| * oI I oI! oI ! I t I oI ao!t oat I I aoIt ott I oo| | I I oost t oI o! o

11-364
II.MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

Fluid Interface Behavior Under Low- and Reduced-Gravity Conditions

PRINCIPALINVESTIGATOR:ProL Paul Concus University of California, Berkeley

Co-INVESTIGATORS:

Robert Finn Stanford University

TASK OBJECTIVE:

The general objective of this research is to gain a better mathematical understanding of the physical behavior of

fluids partly filling a container or otherwise in contact with solid support surfaces, when capillary forces are

predominate. Closely interrelated with the mathematical and computational studies are current and planned

ground-based and in-space microgravity experiments.

TASK DESCRIPTION:

The approach for this project is to pursue parallel theoretical, computational, and experimental studies to explore

equilibrium capillary ti'ee surI'ace interlaces in a variety of geometrical configurauons. The theoretical aspects

include both rigorous mathematical studies and numerical computation. In connection with the scheduled USML-2

Glovebox experiment, two configurations of particular interest, Ior which small changes in container shape or

contact angle can give rise to large bulk reorientation of fluid, have been devised and are being studied: 1) a

movable wedge and 2) canonical proboscis containers. Experimentation is carried out in collaboration with M.

Weislogel at the NASA Lewis Research Center.

TASK SIGNIFICANCE:

Knowledge gained from these studies can lead toward a better understanding of surface phenomena of liquids in

containers in a low-gravity environment, and in particular to obtaining new in|brmation on the significance of

contact angle as an intrinsic physical property. Additionally, development of accurate, new methods fbr measuring

contact angle and new insights lot managing fluids in space can result.

PROGRESSDURINGFY 1994:

Work continued on studying a class of "canonical proboscis" containers. These containers are cylinders whose

sections have the remarkable property that at a prescribed contact angle a "nearly-discontinuous" transition of bulk

fluid occurs, with unbounded rise height over a "proboscis" protrusion; the protrusion can be made relatively as

large as desired. The formal proof of this property was completed (jointly with a student, T. Leise), and the detailed

behavior of solution surfaces has been investigated (jointly with students A. Chen and F. Zabihi). In addition to a

movable wedge container, the proboscis containers will form part of an experiment scheduled for the USML-2

Glovebox. These shapes have possible application to exploiting microgravity for the accurate determination of

contact angle: in this regard, double proboscis containers were designed for the experiment, to permit bracketing of

the determined contact-angle values. Results of our recent joint IML-2 experiment (D. Langbein, principal

investigator) will be useful in the design and interpretation of our USML-2 experiment.

Investigation continued of the problem of the tree surface of a liquid partly ftlling a wedge container (cylindrical

container with a protruding comer in its section) in the absence of gravity, when the contact angles on the two sides

of the wedge are allowed to have different (constant) values. We have now largely characterized the types of

behavior that can occur, some of which are strikingly different from what is possible for the single contact-angle

case. In general terms, for the new kinds of behavior the surface normal is necessarily discontinuous at the wedge

vertex V. Widely differing behavior is possible within this range, depending on the local boundary curvatures on

either side of V and on the particular data. In one explicit example, the existence of a solution with an infinite

jump discontinuity at the vertex is demonstrated. Under other conditions bounded solutions can exist, and under

11-365
II. MSADProgramTasks--Ground-basedResearch Discipline:FluidPhysics

t * ni I |! o t i ! | o g | I a I t i o| i ! o | i a i i o o I o | o tIt o H I | I o | i | | i i 111 | | i Iii o II t I u t I ! t | i t I i oo i i a i i | t i IIt n 01 !011011 * I 0 0 0 | I t I I* II n 01 | 0 01 | t I 011101111 ! 0 | I 010 0 0 J I0 t II | 0 U0 O0 | I 0 01 a01 g 0 | OS| 0 t t! 0 0 01| a ! 0111 |! t. U 010 | 0 u | 0 Urio l01 IH 0 |_ 0 n I Olit tat H t |_i I IO I0 | ! OI I 0 OOOa | _ Ot !

further conditions the solutions must be continuous (this last result follows from recent related work by Lancaster

and Siegel). In general, discontinuities must be anticipated, but we can show that whenever a bounded solution

exists then every solution is bounded. For particular cases, we have verified the behavior numerically. The precise

characterization of all admissible behavior patterns is a principal question that we have started to address.

As part of the design of containers for our earlier USML-1 experiment, the stability of liquid bridges between

parallel plates was studied, for the case of equal contact angles on the two plates. This work was extended by a

student (L-M Zhou) to the case of unequal angles with some surprising results. In the equal angle case, she gave

the first uniqueness criteria, showing that either the bridge is unique or else there are exactly two solutions, of

which only one is stable. Zhou's results display a remarkable variety in possible behavior, depending on the

prescribed contact angles and volumes.

In related work, the possibility of (tubular) liquid bridges spanning two intersecting planes was investigated by a

student, John McCuan. For certain ranges of boundary angles, trivial explicit solutions can be obtained as spheres

with two caps cut off. McCuan shows that no other boundary angles can admit any solutions at all. The result is

put into relief by an example constructed recently by H.C. Wente, of self-intersecting bridges that achieve angles

other than those achievable by spheres. Thus, the physical requirement that the bridge surface not intersect itself is

crucial for the result. An open question raised by McCuan's result is whether the spheres are the unique solutions

when they exist. His result "also suggests that when a spherical bridge exists, if the wedge angle is slowly opened

then the bridge should move into the edge, and possibly break into several disjoint drops in accordance with recent

results of Langbein. These, and the results in the above paragraphs, suggest possible related experiments in

microgravity.

McCuan has also been working experimentally in connection with the "Gravity B" experiment/'or testing the

general relativity theory, which is currently being prepared at Stanford. The vessel is to be partly filled with liquid

helium, and it is essential to have precise estimates as to where the helium will be. The problem is too difficult for

a reliable theoretical study, but McCuan has used invariance properties of the goveming equations to devise and

build a ground-based experimental apparatus. The initial experiments have already been completed and have yielded

significant information.

Analysis of the data from our USML-1 glovebox experiment continues. This experiment concerned axially

symmetric "exotic" containers. The containers, which are in the shape of a right circular cylinder with

mathematically derived toroidal-like bulge, have the property, that they admit in zero gravity an entire continuum of

axially symmetric equilibrium interlaces for the prescribed fluid volume and contact angle. However, it was proved

that the entire container can admit no symmetric stable interlace; thus the energy minimizing interface (which is

known to exis0 must necessarily be asymmetric. This behavior was verified in the USML-1 experiment; as the

fluid enters the bulge in the container, it appears at t-trstas a spherical cap. But in response to a disturbance it

immediately adopts an asymmetric shape. Most of the video tapes of our experiment taken on board USML-I have

now been received, and final analysis of the data awaits arrival of the remaining tapes.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 2

PhD Students: 0

TASK INITIATION: 3/90 EXPIRATION: 3/96

PROJECT IDENTIFICATION: 962-24-05-66

RESPONSIBLECENTER: LeRC

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11-366
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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BIBLIOGRAPHIC CITATIONS FOR FY 1994:

.lournais

Concus, P, and Finn. R.

{1994).

Concus. P. and Finn. R.

FimL R.. and Leise, T.I,.

Fischer. B. and Finn, R.

405-423 (1993).

Capillary surfaces in a wedge: differing contact angles. Microgravity Sci. Technol, VH. 152-155

Capillary wedges revisted. SIAM J. Math. Anal., 11994).

Ou the canonical proboscis. Zeit. Anal. Anwend., 13, 443-462 (1994}.

Non-existence theorems and measurement of capillary contact angle, Zeit, Anal, Anwend.. 12.

Zhou. L,-M. On the volume infimum for liquid bridges. Zeit.Anal.Anwend, 12. 629-642 (1993).

Zhou. L.-M. On stability of a catenoidal liquid bridge. Pacific J. Math.. _1994].

Proceedings

Concus. P. Finn. R.. Weislogel. M. "Interface configuration experiment: preliminary results." in .joint "L+I" Science

Review for USML-1 and USMP-I, Ramachandran. et el,. eds.. NASA Conf. Pub. 3172, NASA Marshall Space Flight Center,

525-539, 1994.

Finn, R. "Gradient and gauss-curvature bounds for H-graphs," In comparison methods and stability theory, xin zhi liu and

David Siegel, eds.. Marcel Dekker, 137-150. 1994,

Finn, R. "Green's identities and pendent liquid drops." 11, Proc. Intl. Symp. Cont. Mech. Rel. Probs. Anal. (ded.

Muskelisvilil. Tbilisi, 1994.

Finn, R. "On the contact angle in capilarity II." Discourses in Mathematics and its Applications, Texas A&M

Mathematics Dept. 1994.

McCuan. J., Neschleba, P.J., Tori, R.H., and Finn, R. "Some experimental results on bubbles near the axis of a rotating

liquid drop." Proc. 7th Marcel Grossman Symp. Genl. Relativity, 1994.

Presentations

Concus, P. "Equilibrium capillary surfaces: theory and space experiments." American Physical Society. Fluid Dynamics

Division Annual Meeting. Albuquerque, Nov. 1993.

Concus. P. "Capillary surfaces in wedge domains: the two angle case." Syrup, on Nonlinear Problems, Wichita State

Univ., April 1994.

Concus. P. "New results of McCuan and of Zhou." Syrup. on Nonlinear Problems, Wichita State Univ.. April 1994.

Concus, P, "A-priori bounds for h-graphs." Univ. Oklahoma, Norman, April 1994.

Concus, P. "Capillary Wedges." Syrup. on Calculus of Variations, Oberwolfach, May 1994.

Concus, P. "Local and global existence criteria for capillary wedges." Univ. Leipzig, May 1994.

Concus, P. "Gradient estimates for h-graphs." Univ. Cottbus, May 1994.

Concus. P. "The canonical proboscis." Univ. Leipzig, May 1994.

Concus. P. "A-priori gradient and curvature bounds for h-graphs." Univ, Bonn. June 1994.

Concus. P. "Stability criteria for liquid bridges." Univ. Leipzig, June 1994.

Concus, P. "New gradient and curvature bounds for h-graphs." lntl, Syrup. on Motion by Mean Curvature. Levico, June

1994.

Concus, P, "Equilibrium fluid interface behavior under low- and zero-gravity conditions." Second Microgravity Fluid

Physics Conf., Cleveland. June 1994.

i i* 1ill 111 |*11 i! i I it llil Iii Iil i u! lUll Iil I I 1! I ! l ! i! ! ! I Iil ! U I i! I i!, ! I I llI I! I It IIi I If Ili l i! IU !IU lUIlII! Illllil I11i.1|11! 111111 Ill I l lIIllll II11| U lIIUl II* 1111 ! I 1! U* .1 **I 11! 11 * 11 I! I g! 11. I * ! I I! 11, I |* ! II 11 ! I I I I * ! I ! I * * * Ii * I I * I I * I I * I i !! I,, 11 * 11,

11-367
Ctmcus. P. "Measurement of capillary c_mtact angle with the canonical proboscis," Drop Tower Days Symp., Univ.

Bremen. July 1994.

Concus, P, "Some results from the interface configuration experiment aboard USML-I." COSPAR '94. Hamburg, July

1994.

Concus. P. "Equilibrium capillary surfaces: experiments aboard the space shuttle." Center for Pure and Applied

Mathematics Lecture Series, Univ. Calif, Berkeley, Sept. 1994.
Convection and MorpholoxicaI Stability During Directional Solidification

PRINCIPALINVESTIGATOR:Dr. Sam R. Coriell National Institute of Standards and Technology (NIST)

CO-INVESTIGATORS:

G.B. McFadden

B.T. Murray

J.R. Manning

National Institute of Standards and Technology (NIST)

National Institute of Standards and Technology (NIST)

National Institute of Standards and Technology (NIST)

TASK OBJECTIVE:

During the directional solidification of a binary "alloy solute inhomogeneities can arise from both fluid flow and

morphological instability. In microgravity buoyancy-driven fluid flow is reduced, and experiments to study the

evolution of morphological patterns without the interference of fluid flow may be possible. The goal is to develop

an understanding of the interaction of fluid flow with the crystal-melt interface so that solute segregation in

solidifying alloys can be controlled in order to obtain materials with superior properties.

TASK DESCRIPTION:

Included in this research are:

1. Calculations of cellular morphologies in the absence of fluid flow.

2. Evaluation of the Seebeck voltage for cellular interfaces as a method for monitoring inter/ace morphology in

metallic alloys.

3. Linear stability analyses of coupled interfacial and convective instabilities.

4. Calculations of the effects of time-dependent gravitational accelerations (g-jitter) on fluid flow during directional

solidification. For growth of a vicinal face at constant velocity, the effect of anisotropic interface kinetics on

morphological stability has been calculated for a binary "alloy. Anisotropic kinetics give rise to traveling waves

tdong the crystal-melt interface, and can lead to a significant enhancement of morphological stability.

This ground based research will focus on providing theoretical interpretation and guidance for a series of space

experiments to be earned out by J.J. Favier, R. Abbaschiani and colleagues on tin-bismuth alloys using the

MEPHISTO apparatus and by K. Leonartz and colleagues on succinonitrile-acetone alloys.

TASK SIGNIFICANCE:

This comprehensive research on the directional solidification of binary alloys will determine the processing

conditions required to eliminate microsegregation of impurities and produce alloys with desirable microstructures

and improved properties. This research will potentially contribute to the important and challenging goal to develop

and transfer to "all of the consortium members (of NIST, US industry, and NASA) technology that will provide/or

the rapid design and prototyping of new precision cast parts, enhance product quality, and reduce rejection rates.

PROGRESSDURING FY1994:

The solute mass transport that may lead to morphological instabilities in directional solidification has been

described within the framework of the nonlinear thermodynamics of irreversible processes. Specific calculations

have been carried out for tin-bismuth alloys for two models of the concentration dependence of the thermodiffusion

flux. Depending on the sign of the thermodiffusion coefficient, morphological stability may be increased or

decrea.,ed.

11-369
IL MSADProgram Tasks -- Ground-based Research Discipline: Fluid Physics

iI I i I I ! I I ! * | ! | |! I g I! ! | I I ! 11 o I ! | I o I |! | ! I I | ! | | I I mi i i I ill i e n I t I! _ iI _ ! i o I i _ i I i iI | ! i ! | I ! e i I ! | i ! Qi | i _ i | 11 | i ! t I i I! i m| i i I i i i I I |i | | i a i i i i | I ! mi I! I ii I I o I ! I ! i ! IIi o I imi I i i i o I io i IQi i J I i J o I | 611 | J iI I ii i I n o i ! t i i i I! o I i ! i I i I i ! i I i | i! ! i i o I i | | I ! e i! I ! i mII | ! ! ! ! t i !i ! | t

We have investigated the effect of anisotropic kinetics on the morphological stability or a pure material growing at

constant velocity into a super cooled melt. The kinetic anisotropy is based on the motion of elementary steps and

the stability of a planar interface with respect to the formation of macro steps or step bunching is considered.

Kinetic anisotropy and capillarity stabilize the interface, while the temperature gradient in the melt is destabilizing.

Linear stability calculations for dislocation and nucleation controlled growth of salol indicate that anisotropic

kinetics provides stabilization for sufficiently low growth velocities for crystals of practical dimensions. Although

the critical crystal size depends on the growth velocity, for materials like salol, instability may occur for dimensions

larger than tens of centimeters, while for materials like germanium the critical size is less than a centimeter.

The effect of a parallel shear flow and anisollopic interface kinetics on the onset of instability during the directional

solidification of a binary alloy at constant velocity has been calculated. A shear flow (linear Couette or asymptotic

suction) parallel to the crystal-melt in the same direction as the step motion decreases interface stability in that the

critical solute concentration decreases. A shear flow counter to the step motion erdaances stability for small shear

rates; for larger shear rates, an additional mode of instability occurs and the critical solute concentration slowly

decreases with shear rate.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-05-40

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Braun, R.J.. McFadden, G.B., and Coriell, SR.

Rev, E49, 4336-4352 (1994),

Morphological instability in phase-field models of solidification. Phys.

Brush, L.N., McFadden, G.B., and Coriell. S.R. The effect of crystalline anisometry on pattern formation in laser-melted

thin silicon films. J. Crystal Growth, vol. 137, 355-374 (1994).

Coriell, S.R., Boisvert, R.F., McFadden, G.B., Brush, L.N., and Favier. J.J. Morphological stability of a binary alloy

during directional solidification: Initial transient. J. Crystal growth, Vol. 140, 139-147 (1994).

Coriell. S.R., Murray, B.T., and Chernov, A.A. Kinetic self-stabilization of a stepped interface: Binary alloy

solidification. J, Crystal Growth, vol. 141, 219-233 (1994).

Lee. Z.H., Lee, B.J., Kang, M.S.. Chung S.M., and Coriell, S.R. Experimental investigation of convection during vertical

Bridgman growth of dilute AI-Mg alloys. J. Crystal Growth. vol. 141, 209-218 (19941.

Van Vaerenbergh, S, Coriell, S,R., McFadden, G.B.. Murray, B.T.. and Legros, J.C. Modification of morphological

stability by Soret diffusion. J. Crystal Growth. (accepted}.

Proceedings

Chernov. A.A., Coriell, S.R.. and Murray. B.T. "Morphological stability of a vicinal face induced by liquid or step flow."

Proceedings of the 7th Topical Meeting on Crystal Growth Mechanism, Atagawa, Shisuoka Prefec., Japan, 1994.

Books

Coriell, S.R.. Murray, B.T.. McFadden, G.B.. and Leonarts, K. "Stability during directional solidification of the

succinonitrile-acetone system," in "Free Boundaries in Viscous Flows. The IMA Volumes in Mathematics and its

Applications," Edited by: R.A, brown and S.H. Davis Springer-Verlag, New York. NY. vol. 61. pp 99-112. 1994,

II-370
Microphysics of Close Approach and Fihn Drainage and Rupture During Drop Coalescence

PRINCIPALINVESTIGATOR:Prof. Robert H. Davis University of Colorado, Boulder

CO-INVESTIGATORS:

No Co-i's Assigned to this Task

TASK OBJECTIVE:

The overall objective of this research is to develop a comprehensive theoretical model of the relative motion, film

drainage, and film rupture leading to coalescence of interacung drops dispersed in an immiscible fluid. Relative

motion due to gravity, thermocapillary migration, and attractive van der Waals forces is considered. This research is

concerned with the microphysics of co_flescence and focuses on the near-contact interaction of a drop approaching a

second drop or a surface or interface

TASK DESCRIPTION:

The overall goal of Otis microphysical research is to predict deformation, till drainage, and collision rates using

fundamental theoretical analyses. The novel method used couples lubrication theory in the narrow separation gap

and boundary integral theory t'or the drop pha_e. Matched asymptotic expansions are used for small times (small

drop deformations) and long-times _draining till regions).

The research program is divided into three components directed at meeting the goal:

1. Near-contact relative motion for nearly spherical drops: The rate of approach and the onset of deformation and

lilm drainage are examined lbr gravity-driven and thermocapillary-driven motion.

2. Evolution of drop deformation during film drainage: As the drops move closer, the natural evolution of the

shape of the thin film separating them is predicted, as is the rote at which this fill drains.

3. Film rupture due to van der Waals forces: When the rate-limiting coalescence step of film drainage causes an

unstable t'tim to become very thin, then attractive van der Waals 10rces pull the drop interlaces together and cause

rupture. The rupture tune and the rupture mode are determined its flmctions of the system parameters.

TASK SIGNIFICANCE:

Drop interactions and coalescence play key roles in a variety of natural and industrial phenomena, including

liquid-liquid extraction, raindrop growth, multipha_se flow, and processing of bimetallic melts within the

liquid-phase miscibility gap. In liquid-liquid extraction of separation, it is advantageous to promote interactions and

coalescence for efficient and lkster operations, while in the processing of bimetallic materials coalescence must be

controlled so that the two materials are uniforu-]ly dispersed in the final product. This research aims to provide a

better understanding or the t'nnt 'tamenud lactors governing drop interactions and coalescence.

PROGRESSDURING FY 1994:

The collision rate of small drops m llear t]ow fields wa_s solved for large Peclet numbers and small Reynolds

numbers. Simple shear flow and uniaxial extensional or compressional flow were considered. The analysis makes

use of the lubrication theory for two drops in near-contact relative motion developed previously. Various trajectory

types were identified (open. closed, semi-closed, collision), and it was shown that collisions do not occur in s_mple

shear flow lot size ratios smaller them a critical valve.

The related problem in which a spherical drop or bubble captures smaller drops or particles by diflusive, convective,

or convective-diffusive mechanisms w_ts solved under creeping llow conditions. This problem has important

environmental applications in the microflotation of colloids and oil droplets from aqueous streams, and

biotechnology applications m aqueous biphasic extraction of cells and cellular components.

II-371
The thermocapillary motion of drops nearly in contact has been studied when two drops are non-conducting or when

a non-conducting drop approaches a contact temperature surface or an interface. These results have been incorporated

in trajectory analyses to predict thennocapillary induced collision rates. When the drops are highly conducting, the

relative velocity reverses sign and coalescence is impossible.

For combined motion due to thermocapillary and gravitational effects, it has been shown that collisions are reduced

or eliminated upon antiparallel alignment of the thennocapillary and gravitational motions in a certain range of their

relative magnitude. For combined Brownian and gravitational or shearing motioni a numerical analysis tor arbitrary

Peclet numbers shows that synergistic effects greatly increase the pairwise collision rate of drops,

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 5/91 EXPIRATION: 5/94

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-00-35

MS Students: 0 MS Degrees: 0 NASA CONTRACT NO.NAG 3-1277

PhD Students: 2 PhDDegrees: 1 RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Loewenberg, M. and Davis, R.H. Near-contact. thermocapillary migration of a nonconducting viscous drop normal to a

planar interface. J. Colloid Interf. Sci., 160. 265-275 (1994).

Loewenberg, M. and Davis, R.H. Near-contact thermocapillary motion of two nonconducting drops. 1. Fluid Mech., 256,

107-131 (1993).

Loewenberg, M. and Davis. R.H. Flotation rates of fine spherical particles and droplets. Chem. Eng. Sci.. (1994).

Loewenberg, M. and Davis. R.H. Gravity-induced coalescence of drops at arbitrary Peclet numbers. J. Fluid Mech..

(1994).

Wang, H., Zinchenko, A.Z. and Davis. R.H. The collision rate of small drops in linear flow fields. J. Fluid Mech.. 256,

[61-188 (1994).

Thesis

Wang, H. "Modeling and expertrnental studies of drop coalescence and phase separation." Ph.D. Thesis. University of

Colorado, 1994.

Presentations

Davis, R.H., Wang, H. and Hawker, D. "Phase segregation due to simultaneous migration and coalescence." NASA Conf.

Pub. No. 3176: 2nd Microgravity Fluids Conf., 101-106, 1994.

iiIiIf 1111 IIIIiiiiltl *IiliiiII! III Ii!IlIOI|IIQl II1111III IIII IIIII IIlie IIIIIl IlI II! IllnI nllii iIIIII ni l|iiiliii iIi iii illIii IJlO Ill III rill IllJJlIllI IiI ItIIIIIIl III III Illnii iil iIiiiii iiiiiiiiiii!ii*iiIifiiii iii IllIIIiI IlllllIIIIIIIlII IfIIIfIIII

11-372
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

.i,,l,l i ,11 ,i, l,l|, i l, i .,, i,, 1,, I,, 1, I i,, i. I l ,,ii, i ,, I, ,if i, i i, i I,,,, I,, l l*l l,l t i* _ItUlt IIlllU'Ul,lllll_ll._l,l,t l¢,l*,l't t I,UlUUlll III l llU_, I,*' l l_ if, U_' l l I l,* t l*,ll, IU I U l l.l l l, 'I*I lUtll l i_lllt l_lllllllil.illl l_,_t*_tI, l, _lallIIU I

Phase Segregation Due to Simultaneous Migration and Coalescence

PRINCIPALINVESTIGATOR:Prof. Robert H. Davis University of Colorado, Boulder

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to understand the interaction and coalescence of bubbles and drops due to

thermocapillary and gravitational effecLs. Modeling is pertormed via population dynamics balances to predict the

rate of phase segregation under the collective or individual action of the driving forces.

TASK DESCRIPTION:

Significant effort is being devoted to the development and performance of ground-based experiments. The

trajectories of interacting drops and the rate of phase segregation are being measured in a transparent immiscible

liquid system under isothermal conditions.

Theoretic',d work is also being perlormed to predict the macroscopic phase separation and drop-size distributions due

to buoyancy and thermocapillary motion and c_v,descence of immiscible dispersion of drops by solving the general

population dynamics equations retaining both spatial and time dependencies.

TASK SIGNIFICANCE:

This research on phase segregation attempts to provide a predictive tool to determine the size distributions of drops

in a heterogeneous immisciable lluid mixture. Inputs from other fundamenud studies on drop interactions and

coalescence are used in population dynamics models to predict the size distribuuons. This research will ultimately

be of use in materials processing, food and beverage processing, and perhaps in the biotechnology industry.

PROGRESSDURINGFY 1994:

The population dynamics equauons for homogeneous dispersions have been solved for droplet growth due to the

separate effects of Browian, gravitation'd, and thermocapillary motion and co_deKence, trod due to the combined

effects of thermocapillary _md gravitational motion and coalescence. For thermocapillary motion alone, highly

conducting drops experience thermocapillary repulsion, m which the smaller drop moves away from a nearby larger

drop due to distortions in the temperature field, thereby preventing coalescence. For combined, antiparallel

gravitational and thermocapillary motion, a collision-forbidden region of parameter space is possible due to the

faster decay with separation distance of the thermocapillary interaction of two drops of bubbles d]an of the

gravitational interaction.

A computer code has been developed for nonhomogeneous dispersions undergoing simultaneous phase separation

and motion and coalescence due to gravity. The rate of phase separation initially increases due to coalescence and

then decreases due to the larger drops moving out of the suspension. A key dimensionless parameter, representing

the ratio of sedimentation and coalescence time scales, governs the process.

Experiments to observe drop coalescence and phase segregation due to gravity have been pertormed with

1,2-propanedioi drops in dibutyl sebacate and with an aqueous biphase mixture of 1% dextran (MW = 500,000) and

5.5percent polyethylene glycol (MW = 8,000) by weight. Results lor the phase separation rate versus time are in

good agreement with the theory and may be used to infer values tor the composite Hamaker constant which

represents the strength of the attractive van der Waals forces.

11-373
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

11 * i I,, i, I | i i t I 16111 | t i | I ! * t I I ttt |lJ H t |1 t i st |! _ i i _ | i, I,, i i* t is _ i s i i J | s i* m| s,,, I I t | l ! t J i! !i | t ! Qt i | I t ! t |! 0 |i ! I i ! I i ! i | I ! | I ItII 0 J ! t I I I t I i * tl * I Ii I t I t ill | I I I!, it t I s ii * | I !. t It ill I I I, IIt IIt i| tiI t il t i !tii t i | t IIt t i | I ti | s ! I, iiI I | |t its it I | t I I t itt I ||, | * i i !

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-05-39

MS Students: 0 MS Degrees: 0 NASA CONTRACT NO.:NAG3-1389

PhD Students: 2 PhD Degrees: 1 RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Wang, H. and Davis, R.H. Simutaneous sedimentation and coalescence of a dilute dispersion of small drops. J. Fluid

Mech., (submitted), (1994).

Presentations

Davis, R,H., Wang, H,, amd Hawker, D, "Phase segregation due to simultaneous migration and coalescence." NASA Conf,

Pub. No. 3276: 2nd Microgravity Fluids Conference. 101-106. 1994.

Thesis

Wang, H.

1994.

"Modeling and experimental studies of drop coalescence and phase separation." PH.D. Thesis, Univ. Colorado.

t Iil itllilil(tt IIIlln i titiitilttll Itlt! itll Itil II ! tl lit| Itlitlii Ill III Ill IIIIti I i i IIIIllt IIIIIt lit (Itt ittll*lllilll Ill Illillilllilltlli itittitlilttltl(llltUtllt(ttlltttIii I it! tntll i Ittl t lit I I I i I ii ili i tl i tlilltti I Illi iS i it il t lit t ili I ti till tIlli I i it it

II-3 7 4

O_-ff-.
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Interaction and Aggregation of Colloidal Biological Particles and Droplets in Electrically-Driven

glozes

PRINCIPALINVESTIGATOR:Prof. Robert H, Davis University of Colorado, Boulder

CO-INVESTIGATORS:

P. Todd

M. Loewenberg

University of Colorado. Boulder

University of Colorado, Boulder

TASK OBJECTIVE:

The objective of this research is to develop a fundamental understanding of aggregation and coalescence processes

during electrically-driven migration of particles for cells) and droplets.

TASK DESCRIPTION:

The research includes the following tasks:

• Development of a theoretical description of electrically-driven particle aggregation by computing the relative

velocity between two particles in near contact with hydrodynamic, electrokinetic, van der Waals, and electrostatic

double-layer interactions, and by predicting the stability conditions and the rate of pair-wise aggregation in a

semi-dilute suspension;

• Formulation of a description of electrically-driven drop coalescence by developing a simplified electrokinetic

description of a charged fluid interface under thin double-layer conditions, and performance of initial computations

tor the interactions between a pair of electrically-driven droplets; and

• Observations of electrically-driven aggregation and coalescence by conducting terrestrial experiments to test the

theoretical description of electrically-driven particle aggregation and observe electrically-driven droplet coalescence,

with the results leading to future design of a flight-based experiment to gather quantitative observauons for testing a

theoretical description of electrically-driven droplet coalescence.

TASK SIGNIFICANCE:

The fundamental study of particle aggregation in electric fields is expected to have practical application to

electrically-controlled cell flocculation tor cell separation and recycle in space-based bioreactors, where gravity

cannot be employed as previously done. Similarly, research conducted on drop interactions and coalescence is

expected to provide an understanding ot electrically-driven demixing of two liquid phases, such as those encountered

in biphasic aqueous extraction of biologic',d cells and molecules under reduced gravity when buoyancy-driven

demixing is weak. Finally, the theoretical descriptions of two charged, migrating particles or drops are expected to

have general scientific and engineering value.

PROGRESSDURINGFY 1994:

A theoretical description of the near-contact interaction of two particles in an electrical field has been completed.

Near-contact particle motion is important because it has a large effect on pairwise collision rates and provides the

essential physics of the aggregation process.

The new results for near-contact interaction of particles during electrophoresis were combined with previous results

for moderate and large separations in a trajectory analysis to predict pairwise aggregation rates of charged particles

with differing zeta-potentials. In addition to hydrodynarmc interactions, attractive van der W"'aals lorces and repulsive

electrostatic forces were included in the analysis. The near-contact interactions were also used to generate the

stability diagram for heterogeneous suspensions in an electric field. The key result is that particle aggregation under

an electric field occurs more easily and efficiendy than under a gravitational field.

!I-375
Experiments were performed to measure the electrophoretic mobilities and zeta-potentials of human and rabbit blood

cells for a wide range or" ionic strengths. The results provide the ranges of s',dt concentrations for which mobilities

differ so that relatave motion and aggregation are possible. Microvideo experiments to observe aggregation have

been initiated, but quantification is difficult since even moderate concentrations ( I q cells) are optically opaque,

whereas very dilute suspensions have very, low aggregation rates.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 3/93 EXPIRATION: 3/96

PROJECT IDENTIFICATION: 962-24-08-10

NASA CONTRACT NO.: NAG8-945

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Davis, R.H., Nichols, S.C.. Loewenberg, and Todd. P. "Electrophoretic interactions and aggregation ofcolloidal

biological particles." Proceedingsofthe 2nd Microgravity Fluid Physics Coherence. NASA Con_rence Publication

3276. 379-384 _1994).

11-376
Theory qfi Solid!flication

PRINCIPALINVESTIGATOR:Prof. Stephen H. Davis Northwestern University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

This work concerns our effort to understand - on a quantitative level - how various factors affect the morphology of

solidification fronts and, hence, the resulting microstructures of the solidified material.

TASK DESCRIPTION:

In the approach, nonlinear stability theory,, asymptotic, and numerical methods are used to investigate the stability

of the coupled systems describing the directional solidification of binary systems from the melt.

TASK SIGNIFICANCE:

The project aims at the theoretical prediction of microstructure in crystalline matenals that would allow the a priori

"design" of new materials. We will endeavor to answer the following central scientific question: How and under

what conditions can crystals be grown in microgravity (I,tg) with different and "better" properties than those grown

on Earth?

PROGRESSDURING FY 1994:

Progress has been made in many areas of solidification including linear and nonlinear stability theories of rapid

solidification in which thermodynamic nonequilibrium effects at the interface are allowed. The dynamics of

trijunctions during phase transition, the emergence of islands in epitaxial growth and the shear stabilization of

morphological fronts have been analyzed, and promising results obtained.

STUDENTSFUNDEDUNDER RESEARCH: TASK INITIATION: 10/87 EXPIRATION: 2/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-25-05-16

MS Students: 0 MS Degrees: 0 NASA CONTRACT No.: NAG3-747

PhD Students: 2 PhD Degrees: 1 RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Anderson. D.M. and Davis, S.H.

Anderson, D.M. and Davis, S.H.

(Sept. 1994).

Local fluid flow and heat transfer near contact lines. J. Fluid Mech. 268, (June 1994).

Fluid flow, heat transfer, and solidification near tri-junctions. J. Cryst. Growth 142,

Anderson, D.M. and Davis, S.H. The spreading of volatile liquid drops on heated surfaces. Physics of Fluids. (to appear).

Schulze, T.P. and Davis, SH. The influence of oscillatory and steady shears on interfacial stability during directional

solidification. J. Crystal Growth, (to appear).

Schulze, T.P. and Davis. S.H. Shear stabilization of morphological instability during directional solidification. J.

Crystal Growth. (to appear).

Skeldon, A.C.. McFadden, G.B., Impey, M.D., Riley, D.S.. Cliffe, K.A. and Wheeler, A.A. On long-wave morphological

instabilities in directional solidification. Euro J. Appl.Math, (1994).

i ii iI I I I oI I oill iii i I I Ill ii i ii i ii i i I i I I l i ii i i i i i i i i i i iI I i i i i i ii ai i iI III i i l i i l i i I I il ol i i i i i I l l I li in i ii iii i ii Ii i ii i Ill Ill Ill OIll Ill III I I I II I Ill OI II I I I OI II I II I II III I I I II Il Ill I I I I I II I I I II I I Ill III l el I, I I I I n ill I eI I I l I I I I IIII I I I I I I II I Il I I I I I I I II I iI I I I

II-377
MicrogravityFoam Structure and Rheology

PRINCIPALINVESTIGATOR:Prof. Douglas J. Durian University of Califomia, Los Angeles

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to investigate the origin of the most striking and least understood rheological

properties of foam by measuring elastic and flow behavior for a sequence of aqueous Ibams with increasing liquid

content. The microscopic structure and dynamics of the foams will simultaneously be characterized by recently

developed multiple light scattering techniques.

TASK DESCRIPTION:

Foam structure and dynamics will be measured directly and non-invasively through development and use of novel

multiple light scattering techniques such as Diffusing Wave Spectroscopy (DWS). Foam rheology will be

measured in a custom rheometer which allows simultaneous optical access for multiple light scattering.

Microgravity conditions will ultimately be required to eliminate the increasingly rapid gravitational drainage of

liquid from in between gas bubbles as the liquid:gas volume traction is increased toward the rigidity-loss transition.

TASK SIGNIFICANCE;

This experiment will constitute the first measurement of how the surprising solid-like elastic quality of loam

vanishes as the volume traction of liquid is increased. The simultaneous measurements will also permit the first

quantitative correlation of macroscopic theological behavior with the underlying microscopic structure and

dynamics, thus providing new insight into the origin of the dual solid/liquid nature of foams.

PROGRESSDURING FY 1994:

In the current funding period we have made important progress both in terms of the development of multiple light

scattering techniques and their application to a model foam system. As for the former, analysis of multiple light

scattering data crucially assumes that photon propagation can be described by a diffusion approximation with source

and boundary terms set by a phenomenological penetration depth and extrapolation length, respectively. While the

accuracy of this approach can in principle be no greater than about 1_,, I_ greater errors are introduced in practice

due to inappropriate treatment of source and boundary terms. I have determined how to average over the penetration

depth, and how to experimentally deduce the extrapolation length. My objective, which is now nearly achieved, is

to put Static Transmission (ST) and Diffusing-Wave Spectroscopy (DWS) theories on th-mer theoretical ground and

advance the reproducibility and accuracy of their application down from the 10% level to the 1% level. This is

crucial if ST and DWS are to be truly quantitative probes of loam structure and dynanucs. In addition, I have

introduced a new optical configuration for DWS experiments which provides tot significantly better

photon-counting statistics and is less susceptible to systematic errors from imperfect laser beam conditioning.

To move towards our goal of simultaneous light scattering and rheology measurements, graduate student Anthony

Gopal and I have recently completed a series of experiments on the response of foam dynamics to shear delormations

in a sample cell consisting of two parallel glass plates, one of which can be translated at uniform velocity in order

to shear the loam. The normalized electric field autocorrelation function is tound to decay nearly exponentially with

time. The value of the cumulant is set by the ratio of sample cell thickness to the transport mean free path of light

and the rate of rearrangement events. The rate of rearrangement varies with the applied shear strain rate. If the

applied shear strain is small compared to the rate of rearrangements in the quiescent tbam, then the measured rate is

unchanged. If it is larger, however, the rearrangement event rate increases and appears to be equal to the shear strain

rate. At still higher strain rates, Lhe shape of correlation function begins to change and it appears that the loam is

beginning to melt; in this regime, the duration of rearrangement events may be the significant time scale.

I I ! 1II i|( II11 i i|l I I I Ill I|1 ! II 1ii1 I|1 Ill III I II 1I1 II11 II I | 111111111 ! i i i i i iii II | 111 t i i 11 | i | I iI | I I iti i l i i | I| II11111111 | illl ii I ii I Ill I II * III I l 1111 ,I I I I I 1111111111111 II I I1111 II 11 I1 II1 | IS 111 II I 11111111111111110 |IS | III 1111 | I Oil || I Ollll| | | II | I# I | I | I | I 11111 | | I |

II-378
Following the cessation of an imposed shear strain, we have "also measured intensity fluctuations and find that the

rate of rearrangements decreases if the total shear strain suffered is greater than about 5_:. For stratus greater than on

the order of one, we find that the rate of rearrangement decreases by a factor of roughly two and remains depressed

until the foam coarsens significantly. This implies that there are important correlations between neighboring

bubbles which result from the coarsening process and that this self-organized structure is naturally marginally

stable.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASKINITIATION: 1/93 EXPIRATION:12/95

PROJECTIDENTIFICATION:962-24-05-73

NASA CONTRACTNO.:NAG3-1419

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Durian. D.J. Penetration depth for diffusing-wave spectroscopy. ,Applied Optics. /submitted),

Durian. D.J. The accuracy of diffusing-wave spectroscopy theories. Phys. Rev. E., (submitted).

Presentations

Durian, D.J. "The physics of foams." Cal State LA, Department of Physics (COLLOQUIUM), 1994.

Durian, D.J. "Bubble dynamics in a flowing foam." UCSB-UCLA Complex Fluids Fall Workshop, 1994.

Durian, D.J. and Gopal, A.D. "Short time dynamics in a coarsening aqueons foam." Bull.Aan.Phys.Soc.39. Abstract for

contributed talk, APS March meeting. 1994.

Gopal, A.D. and Durian. D.J. "Short time dynamics in a coarsening aqueons foam." Gordon Conference on

Macromolecules and Polyelectrolytes, 1994.

Park. S. and "Durian. D.J. "Viscous and elastic fingering instabilities in foam." Gordon Conference on Macromolecules

and Polyelectrolytes. 1994.

11-379
The Influence of Gravity on Nucleation, Growth, Stability and Structure in Ordering Soft-Spheres

PRINCIPALINVESTIGATOR:Prof. Alice P. Gast Stanford University

CO-INVESTIGATORS:

Dr. David jr. Pine Exxon Research & Engineering

TASK OBJECTIVE:

While previous investigations of colloidal crystals have focused primarily on the structures produced in the ordered

arrays, we intend to probe the dynamics of the crystallization process, in particular, focusing on the influence of the

gravitational field on ordering. In this study, we will use a novel new light scattering experiment, known as

diffusing wave spectroscopy, allowing us to monitor particle motion and ordering in an otherwise turbid

suspension. This approach will provide the means to study, on a particle level, a model ordering process in situ.

The application of diffusing wave spectroscopy can thus be viewed as an important new noninvasive experimental

probe of interparticJe dynamics,

TASK DESCRIPTION;

Among the attractive features of aqueous colloidal suspensions are long-range Coulombic repulsions dtminishing

the influence of hydrodynamic interactions between particles. In this system we can observe and provoke

homogeneous nucleation, bcc or fcc lattice formation, defects, twinning and a crystallization growth instability

analogous to those observed in molecular systems. These phenomena motivate and provide a means tbr us to

investigate the role of interfacial tension, transport and gravity in this process. A key feature in this study is the use

of density matching conditions to study the late stages of crystallite growth and ripening without the complicating

factors arising from their sedimentation. In order to investigate the influence of a gravitational field on ordering in

soft-sphere colloidal suspensions we propose to begin with ground-based studies of polystyrene particles of size

ranging from 100 to 500 nm suspended in mixtures of hydrogenated and deuterated water. Choosing an appropriate

mixture of D:O and H+O we can render the suspension neutrally buoyant. In this fashion we will be able to monitor

nucleation rate, growth, and ripening under a variety of gravitational conditions. Future studies on more dense

colloidal particles of technological importance would require actual low gravity experiments.

TASK SIGNIFICANCE:

An additional feature of this research will be an improved understanding of the transport of multiply scattered light

through complex, multiphase systems. Our combination of experiments and theoretical treatments is of

fundamental importance in the understanding of phase transitions and for further applications of diffusing wave

spectroscopy. The interest in colloidal systems as important materials themselves and as model molecular systems

is only beginning to expand to phase transition dynamics. This study will provide a definitive test of the nature of

ordering dynamics, and its sensitivity to gravity. The link to molecular processes will have important implications

for future studies of gas-liquid and solid-fluid transition kinetics.

PROGRESSDURINGFY 1994:

In a previous phase of our work we used diffusing wave spectroscopy (DWS) to study the dynamics in strongly

interacting suspensions of colloidal particles. A detailed description recently appeared in the J. Chem. Phys. (101

(6), 15 Sept. 1994, p. 4975-85). In that work we qualitatively related the interparticle structure to the particle

dynamics by measuring the fluctuations in multiply scattered laser light (DWS). The current phase of our work

focuses on understanding the dynamics in ordered arrays of colloidal particles through similar light scattering

techniques.

Typically colloidal crystals are composed of many small (< lmm) randomly oriented crystallites with disordered

grain boundaries. This makes unambiguous interpretation of the photon scattering rather difficult. To circumvent

this difficulty, we have built a Couette cell in which the shear flow can be used to order the suspensions into

11-380
II. MSADProgram Tasks -- Ground-based Research Discipline: Fluid Physics

.).ll)l.J.lililiiiiila)l .I.I.)l$11))llll)|l.ll.ll01JIIllilIIllll))HIllIIl.l.l.j.l.i)lH).)ll)lllllllJfl;.l||g mH_i"_H_i_|_"_|_"_lt_I)i_II_|_)_))_||_|_n_u_"_))_")_)_)_

_fligned macro-crystalline domains which we then use in our expertments. We are currently perlonnmg experiments

on crysttds at different aqueous umic strengths.

This proposal was recently awarded under the 1993 NRA. Funding for this research began July. 1994.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 7/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-00-83

MS Students: 0 RESPONSIBLEOENTER: LcRC

PhD Students: 1.3

11-381
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Fluid Mechanics of Capillary Elastic Instabilities in the Microgravity Environment

PRINCIPALINVESTIGATOR:Prof. Jtunes B. Grotberg Northwestern University

CO-INVESTIGATORS:

Prof. David Halpern University of Alabama

TASK OBJECTIVE:

The primary objective of this work is to study the fluid mechanics of pulmonary airway closure in the microgravity

environment. This task is also to study the stability of liquid lined flexible tubes with surfactants in the liquid.

TASK DESCRIPTION:

The task proposed to study coupled fluid-elastic instabilities of a flexible tube coated internally with a thin liquid

film by both theoretical and experimental means. The principal investigator will analyze a mathematical model of

post--closure tiring tlows and re--opening phenomena using a similar approach as the closure problem. An

experiment of a flexible tube containing a thin liquid layer on its wall and a liquid core of a much smaller viscosity

but similar density is also proposed.

TASK SIGNIFICANCE:

This research has three important applications: 1) closure and reopening of small airways in the lung, 2) annular

extrusion processes, and 3) two-phase flow in porous and poro-elastic materials.

PROGRESSDURING FY1994:

This grant formally began on June 29, 1994. Research has been conducted to address the capillary-elastic

instabilities of liquid-lined flexible tubes. An experimental apparatus is used to create a mechanical model of flow

in airway tubes. Pulmonary airways are flexible tubes which are lined with a thin liquid film. A small glass tube

of ID=-0.58 ram is viewed under a microscope-- camera configuration. The annular film is created by manually

filling the tube with oil from a syringe. Results from experiments using oil films and a water core in a rigid tube

have been performed, which appear to match well with theoretical values derived by Halpern & Groterg for higher

Capillary numer (CA) values; continued experiments will be performed to match with results over full range of

capillary numers. Research using flexible-walled tubes is planned to follow. The research experiments are being

conducted by a graduate student, Ms. Karen Cassidy, who is partially supported by this grant.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-00-84

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

I i i *I I | I I I I t i | ! I | ! iI I I I | | I | | I | I I DI I |ll Ill | t * _i II| It | t |i |! I | i ill |l| I i| i DI * ! I l _I I | !I | I I t | !Ill | | t | | |I | I I I I I | | I | | | I I II Ill Ill | __| |t I D| I | I I I __I I I I I t I II I I | I I Dt I | t I ! II I I I I I | I I | || I I | | ! I _Ill tI I D_I | t I | t I I I I I |I | DI I __| | I I Ill || | | | I _I I ! It I |; I ! I I ! | t I| _| DI _| I t I

11-382
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

"_"_"_ii_|I_i_Ii_iI_"_"_III"_li_"_iol_i1ell_Ii_allII_"_"_"_|i_"I"I"l_ii_ii"t .i.ii|llo. J61. H OlaJllll.ll011 .ll.l.lllla J|II_IHII.IIH I Itllll.llellllll01g|lllaHI011.1111|l_.lllllllll|llll Jllllll Jl.llllllllHl.ll_

Effects of Convection on the Thermocapillary Motion of Deformable Drops

PRINCIPALINVESTIGATOR:Prof. Hossein Haj-Hariri University of Virginia

Co-INVESTIGATORS:

Prof. A. Borhan Pennsylvania State University

TASK OBJECTIVE:

The objective of this theoretical effort is to extend the understanding of thermocapillary motion of drops by

including drop deformations. The convective transport of momentum and energy as well as the effects of container

walls will be accounted tbr by the work.

TASK DESCRIPTION:

The focus of the initial effort is on the following tasks (a) theoretical work on the boundary-integral formulation for

the axi-symmetric motion and deformation of a drop in a cylindrical container, (b) finite-volume formulation of the

same problem using domain-mapping techniques, and (c) analysis of the transport of a color function to demarcate

the drop boundary.

TASK SIGNIFICANCE;

This research will provide information on the motion and shapes of drops driven by interfacial tension gradients. A

novel feature of this research is that to facilitate the modeling of this phenomenon using a computer, the sharp

boundary between the drop and the surrounding liquid is "smeared" in the computations. The anticipated outcome of

this research is the speed and shapes of the drops under various conditions and an enhanced understanding of how

much the interlace can be smeared before the results are intolerably degraded.

PROGRESSDURINGFY 1994:

In one year we developed a 2D/axisymmetric version of this Navier-Stokes solver which demarcates the fluid phases

using a passively convected color having a constant value over each fluid phase and varying abruptly at their

interlaces. The fidelity of the code was enhanced by implementing a quad-tree refinement of the grid, as well as, a

second-order TVD scheme for the solution of the color equation. During the past year this code was used to study

several physical problems and at the same time work started on the development of the three-dimensional version of

the code. Progress in each area is reported below:

1. The following computational tools have been developed:

a) Color function (3D) - - The extension from 2D to 3D was a major undertaking in the sense that we completely

changed the code and ported our platform from Fortran 77 to Fortran 90. This step was essential for the

implementation of the oct-tree refinement of the grid in the vicinity of the interface. The dynamic array

dimensioning and the link-list structure helped immensely in the development of the data structure for this adapted,

unstructured grid. The TVD scheme was also extended to 3D and is now tested. The fluid dynamical equations are

being coded presently and should be ready and tested in three to four weeks. The quality of this code is better than

any other due to the painstaking attention to the importance of high-resolution near the interface. No other

technique that we are aware of can claim to produce resolutions compared to our technique. The high accuracy

translates into results of quantitative significance as well as qualitative significance. One drawback is the

unsuitability of the nonstructured grid for vectorization; a problem under current consideration.

b) Domain mapping - - In year one a second Navier-Stokes solution method using the mapping of the drop or the

interface of interest onto a known and simple geometry of similar topology was developed. This year it has been

extended to be based on a spectral technique so that more accurate studies addressing stability topics such as weakly

nonlinear hydrothermal instabilities can be addressed.

11-383
2. The following analytical study was conducted:

a) Effect of smearing - - Given that techniques such as ours, or those based on interface tracking, have suddenly

become extremely popular, we performed a study to assess the effect of smearing of properties on various gross

quantities such as the migration velocity, etc. It was shown that whereas the results are rather insensitive to the

smearing of the fluid transport properties (such as viscosity and density), they are quite sensitive to the smearing of

the inteffaciai force into an equivalent body force.

3. The following problems are being studied:

a) Thermocapillary motion of a drop in unbounded liquid - - Using the 2D color-function approach the

quantitative effects of non-zero Re and Ma were observed. The inertial effects are substantial even in the cases where

the drop undergoes very minor delormations.

b) lnterfacial-driven motion in an open cavity - - Using domain mapping the time-accurate flow in an open

three-dimensional cavity subjected to interfacial temperature gradients is simulated.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-00-45

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Haj-Hariri, H., Shi, Q., and Borhan, A. Effect of local property smearing on global variables: implication for numerical

simulations of multiphase flows. Physics of Fluids A, 6, 2555-2557 (1994).

Shi, Q. and Haj-Hariri, H. The effects of convection on the motion of deformable drops. AIAA paper 94-0834. Reno.

(1994).

Presentations

Haj-Hariri, H., Shi, Q. and Borhan. A. "Thermocapillary motion of deformable drops." Proc. Second Microgravity Fluid

Phys. Conf.. Cleveland. OH. June 1994.

Shi, Q., Haj-Hariri, H. and Borhan, A. "Thermocapillary motion of deformable drops." 46th Annual Meeting of the

Division of Fluid Dynamics of the APS, Albuquerque, NM, November 1993.

Shi, Q., Haj-Hariri, H. and Borhan, A. "Thermocapillary motion of deformable drops: convection effects." 47th Annual

Meeting of the Division of Fluid Dynamics of the APS, Atlanta. GA, November 1994.
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

i.l_,,,,l,¢t,¢ .,.mu,,l,,l,.u,,,¢H ,ll,ll,,l,|,,,,l|_,,,,l,_ll,,,,,,_,llll.l,, J|H01111101,,,,B.a,l H lll011.,l,IHa,H a¢,l,,;Slm|ll.ll|.l¢ll|¢llSll,¢tJ, H,ll¢,l J IH*Hl,,l,ll|,t H,,,,,HIHl,,ll¢,,,,ll,I J,lml|,_n|.l.llHl_llHl_.ll,,

Interracial Transport and Micellar Solubilization Processes

PRINCIPALINVESTIGATOR:Prof. T. A. Hatton Massachusetts Institute of Technology (MIT)

CO-INVESTIGATORS:

No Co-rs Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to develop and implement a new diffusion cell for the fundamental investigation of

the effects of surfactants on the mterfacial transport of solutes between two phases. In the one case, the concern

will be the retardation effect the surfactant monolayer has on solute transfer at conditions below the cnticnl micelle

concentrations. This work will assist in determining the effects of interfacial compressibility and solute and

surfactant structure on the activation barriers to transport. In the other case, the rates of formation of micelles and

reversed micelles at the interface will be investigated. These, too, will be affected by the prevailing solution

conditions. To date, this type of study has been hindered because the techniques used for measurement of interfacial

transport processes are prone to artifacts associated with ill-defined hydrodynamic conditions.

TASK DESCRIPTION:

During this task period, we have concentrated on developing a new diffusion cell approach for the measurement of

interlacial transport and solubilization rates without introducing hydrodynamic effects that can complicate data

interpretation and analysis. The technique relies on the fact that many fluorophores can be bleached irreversibly

when exposed to high intensity light sources for brief periods of time. The rate at which fluorescence is recovered

in the bleached zone depends on the diffusion of fluorophores from outside this region. Our task has been to set up

the equipment, to integrate the various components, and to establish a methodology for data analysis. A testing

program to identify the important parameters ranges over which a space-based experimental study would be

beneficial is to be undertaken.

TASK SIGNIFICANCE:

lnterfacial transport and solubilization processes are important in many industrial, commercial and home operations,

ranging from large-scale reaction and separation processes to detergency in dishwashing and laundry applications.

New separation and reaction technologies based on surfactant self-assembly show promise lot reducing the potential

for environmental contamination in many industrial processes, or tor remediation of already contaminated resources.

Through the development of techniques to measure the rates at which the processes of interest occur, and relating

these data to the chemical properties of the systems under study, we will be in a position to design more effectively

the surfactants lbr specific new applications. In some cases, gravity-driven convective currents will complicate the

data analysis and interpretation, and this establishes the need to conduct experiments under the low-gravity

conditions of a space-based experimental program.

PROGRESSDURINGFY 1994:

The new system using fringe recovery after photobleaching (FRAP) has now been set up, and all _omponents

integrated to enable the efficient gathering of images of the new concentration profiles on either side of the interlace

as a function of ume. Video enhancement of these images, and subsequent quantification of the concentration

profiles as a function of time, are now possible, paving the way for a detailed study of the interlacial transport and

solubilization rates Ibr various wate-oil-surfactant systems. The conditions of fluorophore concentration/bleaching

intensity which give rise to unstable density gradients are beginning to de delineated.

i l i il i ii i ii ill i ii l iii i ii ii l i i l i III I l i i i i i i ii ii l i i i i i l i i iiI Il I I I I I I l I l I I l II I I l I l I I l I l l I I II l l el I II I I I III I I II l Ill I tl III III I el III I I I Ill l I I l II I Ill III I I III I II I l I I l III III III I I I l lie ill l ill Ill Ill Ill l Ill Oil I l l I 1lille I I II I I I I I I I l I I I lI I I I l I I l I I l II l ! I l ! I l ! I

11-385
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

q l, *, ii o i a o|1 |* i I o* I|*o, o o laol I.|a o|a o|a_l a o o I o la *la o om i_* i i o i a. * ao o a ,I i *oloollo H illa|loomouooo*l|o*olo||oa Jo*elo*|a a DouomJDoo|oumon i OmUOl0110HOHOHOHOHanOOOlUOOI0tl0n I US00 laoH*laanl l anDHm0O*0DlanHanHa|OOOU|OlIOO001001anHan|II

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 4/93 EXPIRATION: 4/96

PROJECT IDENTIFICATION: 962-24-08-11

NASA CONTRACT NO.: NAG8-951

RESPONSIBLECENTER; MSFC

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11-386
II. MSADProgram Tasks -- Ground-based Research Discipline: Fluid Physics

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Critical Phenomena, Electrodynamics, and Geophysical Flows

PRINCIPALINVESTIGATOR:Dr. John Hegseth University of New Orleans

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

To demonstrate the feasibility of using fluid near its critical point as a compressible fluid tot an electroconvection

experiment.

TASK DESCRIPTION:

Create an experimental system where a spherically symmetric density gradient is established in a compressible fluid.

Such a system called Compressible Geophysical Flow Experiment (CGFE) will mimic the property of planetary

fluid flows. In order to understand how such an experimental system works, knowledge of elements from fields

such as critical phenomena, electrodynamics and compressible fluid dynamics have to be brought together.

TASK SIGNIFICANCE:

This experimental work will help the understanding of the Geophysical flows and their characteristics and direct

consequences.

PROGRESSDURING FY 1994:

This new task was initiated on 8/22/94. We have begun the process of setting up the laboratory, designing the

apparatus, and the temperature and pressure control systems, and testing the feasibility of the mechanical driving. In

addition, we are testing a high voltage A.C. power supply and ordering equipment and parts. The benefits of

studying previous systems will aid in the important design decisions needed for manufacturing the cell. To date we

have purchased a frame grabber, optical diagnostic equipment, parts for the cell, and the temperature control system.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 8/94 EXPIRATION: 8/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-00-85

MS Students: 1 RESPONSIBLECENTER: LeRC

PhD Students: 0

I I I oI I I Ill I I| o! o! I till IoI I oI | I I ol O| ! I I! | ol i oi I ooi ouooooI I I I i I Ol ! i| ! i i i i ! I ol Ill i oi i oI I i i ooi i I! II II III l ii i I I I Ill I I uOI Ul I I OOI O! I OI OIl ! II I ! I I I ! l l I l I ! I! IOI II aI o! i |111 ol l ol ill ! I| I | I oo| II I I II ! II ! ! I !i ii ! Ill | I I I I l ! i ii ! |1 I1! Ill Ill I |I l I! I ill l Ol ii l nll in ni n

il-387
Thermocapillary Instabilities and g-litter Convection

PRINCIPALINVESTIGATOR:Prof. George M. Homsy Stantord University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objectives of this study are:

1. To study the stability characteristics and to establish the conditions under which thermocapillary flows become

three-dmaensional, time-dependent, and/or chaotic.

2. To analyze the g-jitter effects on surface-tension driven flow.

TASK DESCRIPTION:

Complimentary experimental and computational studies will be conducted to characterize the transport phenomena

induced by surface tension gradients or transient accelerations. Experimentally, measurements of various flow

variables will be carried out to elucidate the mechanism of the instability and the dependence of instability on

various parameters of the problem. The range of Marangoni numbers will be extended to study the transitions to

time-dependent flows, and perhaps to turbulence. Linear stability analyses, using a combination of inverse iteration

and Lancozos methods, will be conducted to help elucidate the connection between driven cavity problems and

thermocapillary convection problems.

TASK SIGNIFICANCE:

The results from this study should enhance the understanding of the basic forces acting on fluids in a space-flight

environment, and the accompanying fluid response. Such an understanding can contribute directly to better the fluid

handling/management technologies. This can help improve planning and execution of any space experiment that

has fluids involved, thus maximizing the science/technology return pursued by these space-flight experiments,

which encompasses a wide range from materials processings to biomedical research.

PROGRESSDURING FY1994:

This project involves study of two distinct problems in microgravity convection: thermocapillary convection and its

stability, and g-jitter convection.

In FY94, progress on the former has consisted of completion of computational studies of the stability of the lid

driven cavity, the results of which have been published. A manuscript on our experiments on the stability of

combined buoyancy-thermocapillary convection in a cavity has been submitted for publication in the Physics of

Fluids and has been favorably reviewed. An outstanding postdoctoral student from Prof. Tom Mullins' group at

Oxford will join us in early October. He will continue our experimentation on thermocapillary cavity flows.

Studies in g-jitter convection have been conducted by a PhD student, Ahmed Farooq, who has just successfully

completed his PhD thesis defense. A first paper on g-jitter convection in a cavity has appeared and his thesis is

complete. A second paper dealing with instabilities and chaotic convection accompanying high amplitude g-jitter

convection is in the final stages of preparation.

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II-_88
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

_*_*_*_a_niIn_"_"1|_n_in"n"n|_n"HI_"I|_n_l_"n"_"_Ii_j_|n"lnnn_nII_lI_li_||n_|_ni_nj_i_niln_"_i_n_181_8n_Hi||_|_i_l|_"_|_u_|o_6i_"_ J| H,,,sl*|*lI.H**.n,.,l,,,,lH,81nln,,nnnn,.,n,,,,,

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 4/93 EXPIRATION: 4/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-48

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: l

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Farooq, A. Linear and non-linear dynamics of forced periodic natural convection flows. PhD Thesis. Stanford University,

(August 1994).

Farooq, A. and Homsy, G.M. Streaming flows due to g-jitter-induced natural convection. J.Fluid Mech., vol. 271. 351

(1994).

Ramanan. N. and Homsy, G.M. Linear Stability of lid-driven cavity flow. Phys. Fluids. vol. 6, 2690 (1994).

i i i i ii iii i ii I i i i I i i ii i i i I i i I i i ii i i i i i I i i iI I ii i i i i i i i i i i ii i ii I i i I I i i i i i I II I Ii I ii i Ii i ii i ii i i I I ii i ii i I I III I I I i I III I III Ii i i i i i Ill I I I I I I I I i ii ii i i ii i II I I II I I I lII i I I I I i i l I I I I i ii ii i i i i i i I ii i i i I I i i i i i i ii i ii i i i i i i i ii i i i ii i i i i i i I i l ii i ii i i i i i i i ii i i i i ii i i i i

II-389
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Kinetic and Transport Phenomena in a Microgravity Environment

PRINCIPALINVESTIGATOR:Prof. David Jasnow University of Pittsburgh

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

Theoretical research will be carried out in several areas which involve kinetic and transport phenomena in a

microgravity environment. Specifically, attention will be paid to a number of two-phase phenomena in which

thermocapillarity effects play an important role. These include, kinetics of phase separation, coupled diffusing

t-_elds (e.g., temperature and concentration) and the motion of and transport through two-phase interfaces.

TASK DESCRIPTION:

Methods proposed include modeling of conserved order parameter dynamics in two-phase situations at the coarse

grained or semimicroscopic level. Optimized codes are being developed to carry out the modeling. Coupling of

order parameter to hydrodynamic fields and temperature fields are included. ThermocapiUary effects such as

thermomigration of drops and coalescence are observed, characterized and the underlying physics analyzed. Modeling

will also be performed using techniques developed in the study of dynamical systems.

TASK SIGNIFICANCE:

The modeling at the coarse grained, semimicroscopic level allows description of phenomena over length scales

ranging from the correlation length on up to semi macroscopic sizes. Local thermodynamics is included using the

coarse grained free energy. The interlace motion is naturally tracked and surface tension dependence on temperature

and other parameters is naturally included in the specification of the coarse grained free energy. Hence universal

features of transport in complex situations can be extracted, and, for example, examination of phenomenological

boundary conditions can be performed at a somewhat more microscopic level.

Modeling from the perspective of dynamical maps abandons the familiar partial differential equations of the subject,

but preserves the essential physics, symetries, etc. Here, if successful, a substantial improvement in computational

efficiency can be achieved, at the cost of being able to compute specific material-dependent quantities.

PROGRESSOURINGFY1994:

The main effort under this theoretical project during this period has been to observe thermocapillarity effects such as

thermomigration in two-phase systems, within a coarse-grained, semimicroscopic description, to characterize the

phenomena and to understand the physical meclaanisms for them. There are three main areas of progress: (a) The

response and dynamics of a two-phase interface, in a coarse grained description, to a temperature gradient: (b)

Thermomigration phenomena and phase separation kinetics in a temperature gradient, where the dominant effects are

diffusion driven; and (c) A study of two-dimensional capilarity driven motion of single and multiple droplets, and

phase separation kinetics, including hydrodynamical effects.

Project (a) was designed to gain insight to the effect of a temperature gradient on a two-phase interface. Both using

analytic approaches and numerical relaxation methods for the dynamics of a nonconserved order parameter, we have

determined the motion of an interface for a nonconserved order parameter under a temperature gradient, and have

analyzed the free energy landscape/or an interlace under different boundary conditions.

In (b) we observe, and analyze using arguments derivable from the coarse-grained free energy for the system,

thermomigration phenomena in purely diffusive systems. Temperature variations of the interracial free energy drive

the motion, which occurs via diffusion. We have also considered phase separation phenomena in a temperature

gradient to investigate potential anisotropy in domain growth introduced by the gradient.

_t_tt_t_Itn_nt_t_t_tI_t_tt_ttttt_tutt_t_t_t_tt_ttn_u_ett_n_t_*tt_tt_t_t_t_I_n_nt_t_t_t_n_n_**_t_tn_nt*_o_t_t_t_u_tt_*t_iutt_tut_gt_t_t_t_t_t_nuu_tn_

I1-390
In(c) we have developed a new method lor forward integraung the coupled dynamical equations/or a con_rved order

parameter (at the coarse grained, semimicroscopic level) and hydrodynamic flow fields for two-phase systems in two

dimensions using a biharmonic ,solver. The method has been tested on single drop thermomigration in a

temperature gradient, simple multiple drop configurations, coalescence, and phase separation kinetics.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-05-42

RESPONSIBLECENTER: LeRC

II-391
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

ill|lllinl|nl|nll|ll|t !|n|in!||_i|_II_l!tl|||_II_!o_|I!I1_|I_i|_i_|i_gn!o_!!oli_|I_I_|l_||_i|_I!_i||_n|_I|_i!_|| J||mlo|ll|l!|m|l|ll| |_i|_I0!!i|_ii_Qi_il_i_|gn_i|!il_!o_o_ii_|n_i|_||_I|_l|_i|_i|_lI_l_|!_iIn|i_||_|ioI|_gl_|_n_I_|I_t i

Surfactant-Based Critical Phenomena in Microgravity

PRINCIPALINVESTIGATOR: Dr. Eric W. K_der University of Delaware

Co-INVESTIGATORS:

M.E. Paulaitis University of Delaware

TASK OBJECTIVE:

Our objective is to characterize by experiment and theory the kinetics of phase separation and the metastable

structures formed during phase separation in a microgravity environment. The system we are studying is a mixture

of water, nonionic CiEj ethoxylated alcohol surfactants, and supercritical CO__at temperatures and pressures where

the coexisting liquid phases have equal densities (isopycnic phases).

TASK DESCRIPTION:

1. Locate and characterize ordinary and tricritical points in surlactant/water/SCF mixtures about which two

coexisting phases will be matched in density.

2. Examine using scattering methods the non-equilibrium structures inside both the spinodal and binodal regions

after quenching with either temperature or pressure jumps through or near a critical point.

3. Examine the kinetics of mixing of two phases "quenched" into one phase.

4. Carry out polymerization in a non-equilibrium phase.

TASK SIGNIFICANCE:

The potential ability to control the phase separation of liquid mixtures in a microgravity environment has led us to

investigate novel processing strategies lot materials synthesis in space. As a cost-effective Ihst step in this research

program, we have begun to examine phase separation kinetics and materials synthesis under shnulated microgravity

conditions in earth-based experiments. These conditions are achieved by using mixtures of surfactants and highly

compressible surecritical fluids at elevated pressures to produce two co-existing fluid phases of equal density, thus

eliminating the density differences that normally drive phase separation. The driving Ibrce tor phase separation is

obtained by rapid expansion of the supercritical fluid, which can also be polymerized to kineticatly capture fluid

structures in order to measure their physical, chemical, and mechanical properties. Our goal is to explore different

processing strategies and the fabrication of a wide range of materials that would eventually be manuIactured in

space.

PROGRESSDURINGFY 1994:

In this report, we describe experiments to locate isopycnic equilibrium phases and to determine "local" phase

behavior and critical phenomena tor the three-component mixture: water, CO,_, and the surfactant C8E5. In addition,

we report the results of small angle neutron scattering (SANS) experiments to characterize microstructures that exist

at different fluid densities tot mixtures of the surfactant C_:E6, CO,., and D:O, and our progress in constructing a

light scattering instrument.

Ternary mixtures of a nonionic C_Ejsurfactant, CO2, and H:O will lorm three coexisting equilibrium phases at

elevated pressures and ambient temperatures. These phases are a H:O-rich liquid, a CO2-rich gas, and (3) a fluid

phase with properties that can be adjusted between those of the other two phases depending on the pressure. In

preliminary experiments on mixtures of C8E3, COy and HzO, we determined that the densities of the H:O-rich liquid

and the third fluid phase would approach one another with increasing pressure. Based on these experiments, we then

predicted the temperatures and pressures at which isopycnic phases would form using an equation of state we

_iI_u_i_o_i_o_n_i_u_nu_B_n_nn_n_n_n_*I_n_I__g_o_n_n_n_I_u_n_n_n_u_

I1-392
developedtotsuchmixtures.Asaresultof our calculations, we conducted experiments to search for isopycnic

phases for mixtures of C,E_ and C_E5 with CO, and H:O at temperatures near 40°C m_d pressures up to 400 bar. A

phase inversion was observed for the HzO-rich liquid and the second fluid phase at approxtmately 32 '_Cand 396 bar.

and 30 °C and 310 bar. Wetting phenomena (i.e., the formation of large spherical droplets of one phasc within

another) were 'also observed at these state points. The densities of the two phase were measured at approximately 30

C, and the density difference w&,_found to decrease with increasing pressure from 1.8 x 10.3g/cc at approximately 91

bar to 3.0 x 104 g/cc at 142 bar. These measurements support our predictions of an isopycnic state point for

mixtures of C_E3, CO2, and H:O, and suggest that isopycnic phases will exist at accessible pressures and

temperatures for mixtures of C,E3, CO2, and HzO as well. Our search for these isopycnic state points continues.

SANS measurements were made on mixtures of C,2E_, CO_., and D20 in the water-rich, single-phase region at 7.5

wt % Ct2E 6 (CO2-free basis) in solutions containing different amounts of CO 2. The distinguishing feature of these

measurements is the observed upturn in the neutron scattered intensity, on an absolute scale, as the magnitude of the

scattering vector decreases. This feature is usually attributed either to the presence of the attractive interactions

between the C.zE_ micelles or to critical scattering. Assuming that particle orientations and interactions are

decoupled, it is possible to separate the effect or" particle shape (form factor) and interactions (structure factor) on the

measured intensity. Given the shape of the curves, a modified Ornstein-Zernike structure factor together with a

polydisperse spherical form factor were chosen to model the data. The fits of the model to the data were excellent.

An increase in osmotic compressibility with increasing CO2 concentration is observed which indicates an increase in

attractive interactions as CO2 is added. This observation is consistent with two other experimental observations: a

depression in the cloud-point curve with increasing CO2 concentration and negative excess molar volumes for

mixtures of H20 and CO 2 with a similar surfactant, C8E5 The lack of any significant change in either

polydispersity or size of micelle with increasing CO_, concentration leads to the conclusion that CO_ has a minimal

effect on colloidal microstructure at these concentrations. This is supported by the variation in the contrast

parameter with pressure, temperature, and CO: concentration. Using the variation of this parameter, it was

determined that little or no CO2 was entering the micelle, but instead remained in the water where it was below its

solubility limit.

An apparatus for high-pressure light scattering has been designed and assembled. The key component of this

apparatus is the sample cell, and we have tested tkst quartz and then sapphire as materials of construction that can

withstand high pressures. A preliminary theoretical analysis of scattering has also been undertaken, following the

work of Binder and coworkers, who have predicted the ttme variation of the structure factor for a mixture undergoing

phase separation.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-00-75

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 2

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Kao, C.-P. Pozo. M.E. and Pauiaitis. M.E. Equation-of-state analysis of phase behavior for water-surfactant-supercritical

fluid mixtures. ACS Symp. Ser. 514, 74-91 (1993).

11-393
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

¢ I I I II I III I | I I I I I I I I I I I I | I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I t I I I I I I I I I I I I t I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I | I I I I I I I I I I I t I I I I I I I I I I I I I II I I I I I I t I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I

Instability of Velocity and Temperature Fields in the Vicinity of a Bubble on a Heated Surface

PRINCIPALINVESTIGATOR:Dr. Mohammad Kassemi Ohio Aerospace Institute

CO-INVESTIGATORS:

Dr. Nasser Rashidnia NYMA, Inc., NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The objective of this combined experimental/numerical work is to investigate the fluid flow and temperature fields

in the vicinity of a bubble attached to a heated solid surface. The goal of the research is to investigate the

interaction between thermo-capillary and natural convective flows in the vicinity of the bubble and identify

numerically the parametric range/'or which unsteady periodic oscillations occur on earth and in the low-gravity

environment. It is hoped that the experience gained during this investigation will aid in designing and proposing

the right space experiment in the future.

TASK DESCRIPTION:

Ground-based experiments are performed to identify the following criteria:

1. the appropriate experimental design and fluids

2. the required diagnostic tools

3. the parametric ranges for which oscillatory flow and temperature fields are obtained.

A numerical model is developed and its accuracy will be tested by ground-based experimental results. The verified

numerical model will be used to predict the fluid flow and temperature fields in the low-g environment. Drop tower

experiments will be performed to experimentally verify the effects of low-g environment on the temperature and

flow fields. The experience and knowledge base gamed during this eflbrt will be used to design an experimental

system for both 1-g and low-g applications.

TASK SIGNIFICANCE:

The oscillatory thermocapillary phenomenon is not only of fundamental importance in understanding the behavior

of fluid flow in space, but it additionally has a practical significance in materials processing. For example, in

crystal growth, the oscillatory temperature and flow fields created by unavoidable bubbles next to the solid-liquid

interface may seriously affect the quality of the emerging crystal. In addition, the results of this investigation will

enhance our understanding of the role of capillary forces in fluid management and boiling processes in space.

PROGRESSDURING FY 1994:

Although the funds for this research were initiated in Fall of 1994, significant progress has "already been made. The

design and construction of a test cell for preliminary experiments has been initiated. Interesting results have been

obtained using this simple test cell. Application of Mach-Zehnder intefferometry in 1-g experiments

simultaneously with a laser sheet flow visualization technique has enabled the observation of steady and periodic

oscillatory motions in the vicinity of the bubble on a heated surface.

As part of the theoretical/numerical study, the equations describing the temperature and fluid flow fields around the

bubble were formulated and cast into dimensionless form using appropriate scaling parameters. A finite element

numerical model was developed and used to simulate the temperature and fluid fields around the bubble. Steady slate

temperature and velocity fields predicted by the finite element model are in excellent qualitative agreement with the

experimental results. More rigorous quantitative comparisons are underway. A parametric study of the interaction

between Marangoni and natural convective flows including conditions pertinent to microgravity space experiments

are in progress.

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!I-394
lI. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

t ll ! I I I I ! I I ! I I I I I I I | I I I I I I I I ! | I I I I | | I I I I I I I I $ ! I ! I I I I | I I I I | | I ! ! I I I I I I I I $ I I ! t I I I I I I ! | I I ! I I | I I I I I I I I! I $ | I I | I I ! I I I I ! I I $ I I I I | I I I I I I I I I I I I I | I I I I I | I I I | I ! I I I ! | I | I I I I I I I I I I I I I I I I I I I I I I | I I I I I I | I ! I I I I I ! I | I I I I I I I | I I I ! I ! I I I I ! I I ! I I ! I I | I I I I I I I I I ! ! f I ! I I I I I I I I !

STUDENTSFUNDEDUNDER RESEARCH: TASK INITIATION: 12/94 EXPIRATION: 12/96

PROJECT IDENTIFICATION: 962-24-05-86

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Rashidnia. N. "Instability of flow and temperature fields in he vicinity of a bubble on a heated surface." presented in the

2rid Microgravity Fluid Physics Conference, NASA Lewis Research Center. Cleveland, OH, 1994.

I I I l I I I I I Ill l II I I l I Ill l II I I II I I I l l I el III I l I I l I II III III l lllll l lll Ill l I I lll II O |1 Ill I I I II I Ill Ill I lOll I I I Oil hi lOll Ill nllnlell |tl n illll l llnll Ill l lll I I I l I I I I to I II I I I I I II I l I l I II I I I l I I II I I I I I I I I I II I I l I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I ! I I I I I I I I I I I ! I ! I

11.-.395
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

ll0 HHntlItH|U|||tttlU_.J|III|IllSlelIHlUIIIIItltlSIIIIIIJlI.II_ H ll.ltllll|lHl|lt It H|lllll*ll011*llS|lHIllltlt_lIHIl||l J lmltllttllllll|l|H IH .I.lUlI_|_||_I_.I. H_I.IIH=.I_IIHItllUI_IlUlHIIItt t|Hl|tlt H_llt_t_ H t II

Stabilization of Thermocapillary Convection by Means of Nonplanar Flow Oscillations

PRINCIPALINVESTIGATOR: Prof. Robert E. Kelly University of California. Los Angeles

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

It has been demonstrated theoretically that small amplitude, nonplanar flow oscillations can stabilize

Rayleigh-Benard convection. The first goal of this research is to discern if similar stabilization can be achieved for

the therrnocapillary (Marangoni) instability by the same means.

TASK DESCRIPTION:

An asymptotic expansion based on Reynolds number will be used to perform stability analysis on both

Rayleigh-Benard and Marangoni-Benard convection. A numerical approach using a Fourier representation in the

horizontal directions and a spectral approach in the vertical direction will be used to obtain a coupled set of ordinary

differential equations in time which can be solved by use of Floquet theory.

TASK SIGNIFICANCE:

If stabilization is possible, then the effects of finite amplitude oscillations will be determined in order to see how

much stabilization is possible. And if significant stabilization is predicted, an experiment will be proposed at a

later time.

PROGRESSDURINGFY 1994:

During the initial phase of the investigation, an analysis suitable tor small amplitude oscillations was carried out.

These results have now been accepted for publication (Or and Kelly, 1994). The main conclusion is that the

oscillations can be either stabilizing or destabilizing, depending on the deformability of the surface of the fluid layer.

For low deformability (i.e., small Crispation and Bond numbers), stabilization is predicted whereas destabilization is

predicted for high deformability.

The focus during the current phase has been determining the extent to which stabilization or destabilization can

occur for finite amplitude oscillations by means of a numerical analysis. Preliminary results reported at the 2nd

Microgravity Fluid Physics Conference indicated that changes of 300-500% in the critical Marangoni number can be

realized for moderate values of characteristic Reynolds number (nearly 25), and so the effect should be observed

readily in an experiment. The numerical calculations are being done by Dr. Arthur Or.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 2/93 EXPIRATION: 2/96

PROJECT IDENTIFICATION: 962-24-05-56

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Or, A.C. A shooting scheme for boundary-value problems. J. Comp. Physics A. vol. 3, 280-183 (1994).

Or, A.C. and Kelly, R.E. Onset of marangoni convection in a layer of fluid modulated by a weak nonplanar oscillatory

shear, accepted for publication by Int. J. Heat Mass Transfer.

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11-396
Presentations

Kelly, R.E. "Stabilization of thermocapillary convection by means of nonplanar [low oscillations." Presented at the 2nd

Microgravity Fluid Physics Conference. Cleveland. OH, June 1994.

Or. A.C. and Kelly, R.E. "Stabilization of marangoni convection by means of nonplanar shear oscillations." AIAA paper

94-0242. presented at 32nd Aerospace Sciences Meeting, Reno, NV. January. 1994.
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Microgravity Heat Transfer Mechanisms in the Nucleate Pool Boiling and Critical Heat Flux

Regimes Using a Novel Array of Microscale Heaters

PRINCIPALINVESTIGATOR:Prof. Jungho Kim University of Denver

CO-INVESTIGATORS:

Cameron Moore University of Denver

TASK OBJECTIVE:

The objectives are to determine the relative contribution of the various heat transfer mechanisms to the overall heat

flux in a sub-cooled, nucleate pool boiling in a microgravity environment, and to obtain quantitative data measuring

local heat transfer coefficients at critical heat flux conditions.

TASK DESCRIPTION:

A two-dimensional array of microscale heaters will be used for these tests to provide control and make

measurements. These heaters will be kept at a constant temperature and their power input will be measured to

control the heat flux. With the ability to measure and control temperatures and heat flux over very small areas, it

should be possible to adequately quantify some of the behavior during nucleate pool boiling and critical heat flux

during various stages of bubble growth. Testing would be limited to normal gravity tests.

TASK SIGNIFICANCE:

The development of such a microscale heater could significandy enhance the state-of-the-art in scientific

instrumentation in the area of flow boiling and two-phase flow. Understanding the boiling phenomena has

tremendous impact on electronic cooling and the nuclear, oil, and electric power industries.

PROGRESSDURINGFY 1994:

Based on a proposal submitted to the Annual NRA, a grant was awarded in May 1994. Progress on the project has

been made in two main areas: the heater construction, and the electronic hardware.

All of the steps necessary to fabricate the heater array has been performed using some dummy masks, verifying the

feasibility of constructing the heater. Work is being performed on identifying an appropriate process by which to

construct a resistor with the desired characteristics.

A prototype bridge circuit to be used for the heater feedback loop was constructed and tested using a thermistor

(which has a negative temperature coefficient of resistance) as the heating element. With low current, the circuit

was able to detect a breeze blowing through a window. With high current, the circuit was able to maintain a

constant temperature high enough to boil water. A printed circuit board containing 16 of these circuits per board is

currently being laid out, but final design of the circuit must walt until the actual heaters to be used are available.

Ten of these cards (for a total of 160 circuits) will be used to control the heater array. Much of the design of another

circuit that interfaces between the computer and the feedback circuits has been completed. This circuit will enable

computer control of the control resistor values in the feedback loop, which will allow the temperature of the heater

array to be changed very easily.

__D__|____!______e____|________!_________D_||____!___________D_|_|___|_!|_D_______||__!__!!|___D_e|_!______________!______ee|_e___e__|__|_____________________|_____________D____|__!___ee|__|_!___|__|D____e__|___!_________________!||________|__|

I1-398
|I. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 5/96

BS Students: 1 PROJECT IDENTIFICATION: 962-24-00-87

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 0

I I t I I I I II o II I oI I I I oI I I I oII I I I I II I I ooI ooI I I I I I oI I I i l oi II I I I I oI uI I I I I I II I I on! oII oi i oi i i i ai i ai i i i i i l ai I lll II Ill n illlO i ii ill i i i i iii i i i i i i i i lUi i ai i ii i i ai i i i i aii i i i I i i lliii i i l i i Uoaai ii i ii i i ii i i ui i l i i oi iaoi i I i i i ii i i i i i i i i ooi oi i i ii i i i i i i i i i i i ui i i i i i i i

11-399
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

n. Ilolllll|la.l|ll.llona¢lvo_lntll0olo|lloluonnolllo H InauIUlOlI|Hnm .qll_llo. it t.no.l|loollllBIIBIl_llUllllonaonlooll_nl|llu_ll=lll--nlllulll JHOOlnolI.a.nOolI=OI.I|_I.n._IalnolnonoHO_IO|U_H OOn.lUI.IO|III_._noI|o_nolIOluu

Molecular Dynamics qf Fluid-Solid Systems

PRINCIPALINVESTIGATOR: Prof. Joel Koplik City College of New York

CO-INVESTIGATORS:

J.R. Banavar Penn State University

TASK OBJECTIVE:

The purpose of this theoretical research is to examine the molecular behavior of fluids in small cont'mements and

near boundaries, using molecular dynamics calculations and the statistical mechanics of classical fluids. It looks at

tune and spatial scales where continuum fluid mechanics provides no insight.

Examples investigated are: (1) static and flowing pure fluids near walls, (2) freezing transition in small pores, (3)

the breaking and coalescence of droplet interfaces driven by gravity of flows, and (4) droplet spreading on solid

surIaces.

TASK DESCRIPTION:

The numerical calculations are based on Molecular Dynamics, wherein one integrates the (classical) equations of

motion for interacting molecules of various species, based on a prescribed interaction and specified thermodynamic

operating conditions and mechanical forces. Within the framework of molecular dynamics, it is straightforward to

impose a desired value of gravity or stmulate the presence of g-jitter.

TASK SIGNIFICANCE:

We intend to carry out a number of calculations involving coexisting liquid, vapor and solid phases under flow

conditions, with two common features. First, the systems will be studied at the molecular scale to obtain otherwise

unavailable information. Second, the problems to be studied deal with fundamental issues in the physics of fluids

and interlaces that are of relevance to the microgravity program.

PROGRESSDURING FY 1994:

We have carried out molecular dynamic simulations of fluids of simple linear molecules between two parallel

atomic plates. Our locus has been on monitoring the behavior of the surface layers in very narrow channels for

flowing and for supercooled liquids. While both no-slip and slip behaviors are tound, depending on the wall-fluid

interaction, the behavior of flows in molecular-sized channels is found to be described by continuum hydrodynamics.

While the amorphous surface layers do not make the fluid flow non-Newtonian, they suppress the novel

wall-induced mechanism of fi'eezing observed in fluids containing spherical molecules. Indeed, we were able to

observe the return of the wall nucleation mechanism on reducing the bond length of the molecules. We have also

simulated the stick-slip motion of two atomic plates separated by a lubricant layer made of either spherical or

dumbbell molecules, in order to evaluate the changes caused by the additional degrees of freedom of the confined

fluid. The simple phenomenon of ordering and disordering of the lubricant associated with stick and slip is

supplanted by more complex behavior in the presence of dumbbell molecules.

Studies are underway of effects of a nearby wall on a ball falling in a fluid. In the bulk, Stokes' law relating the

force on a solid ball to its velocity is reproduced by the molecular dynamics simulations. Continuum studies,

primarily due to Brenner, have locused on the force and torque on a ball as it gets close to a solid surface. Our

results indicate excellent agreement with the continuum calculations until the ball gets to within a few molecular

diameters from the wall at which point, deviations are observed. The effects of the molecular structure of the wall

and the ball, the wetting properties of the wall surface and roughness are currently being probed.

LI I II |11 alll Ol gOUUI OO0OI O|11 OOI |81 OSOOI I OI I | | I |OOOOI I OI | OI nOI uOI aOI aOII euIeI I ! | l e! I I I O! I1!I B! I I I I ! Ol IlO I I ql|I OI n| I nOnuI Ul ! l aO III OII IIII III III III oIll I IIII o! I ! ! OI nII log O |Ill I 01Ill III Ill II I |11 Ill DULl$1 ! 01! | I_g115I O_l! I| | I0 | II|lSe( |81 |l I I 01 ! I I ILl I _l I |ll H! I

11400
[I. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

i i|al.lolHinallllllllonlell. J|llolalnloH o ollalaoavlolllnn "I_on_goi_onI_H_no_n"n_H_H_o_"_i_"_oo_oo_ooo_n_o|_o_lo_n_lll_n_ll_nonnH_oIoHu_u_eH 0IO00OaIll0Ul000OOOl0H O0O011nIIIOlIO01OHO0OOIIIOmOOOUOOlOO

We have studied the small-scale dynamics of the apparently singular flow which arises in the sliding plate problem,

a driven cavity flow where discontinuous boundary velocities at comers produce a shear stress singularity. MD

simulations indicate that the singularity is smoothed by fluid slip accompanied by non-Newtonian behavior in the

comers, although the flow is in good agreement with Navier-Stokes calculations elsewhere. The results are not

compatible with a Navier slip boundary condition, however. By consideration of a range of Reynolds numbers, we

find that the non-Newtonian behavior is associated with strain rates comparable to the internal frequencies of the

molecular motion.

In order to explore the origins and dynarmcs of hysteresis in spreading processes, we have done MD simulations of a

Wilhelmy-plate apparatus, in which a solid plate is drawn through the interface between immiscible fluids. The

force vs. velocity characteristics, advancing and receding contact angles, and the velocity and stress fields associated

with the contact line motions have been obtained. We have also extended our earlier study of terraced wetting

phenomena, by simulating the spreading of drops made of longish chains (lengths 8 and 16) on a substrate. The

growth velocity of the layers appears to approach sqrt(t) as the molecule length increases, confirming an earlier

conjecture on the difference between our original simulations and experiment.

We have written an systematic review of MD simulations of fluid flows, which will appear in next year's Annual

Review of Fluid Mechanics.

STUDENTSFUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 4

TASK INITIATION: 6/90 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-00-43

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Keblinski, P., Ma, W.-J., Maritan. A., Koplik, J. and Banavar, J.R. Domain growth near a wall in spinodal

decomposition. Phys. Rev. Lett.. vol. 72. 3738 (1994).

Keblinski, P.. Maritan, A. Toigo, F., and Banavar, JR. Continuum approach to diffusion-limited-aggretation type of

growth. Phys. Rev. E49, R4795, (1994).

Keblinski, P.. Maritan, A., Toigo, F., Koplik. J. and Banavar, J.R. Dynamics of rough surfaces with an arbitrary

topology, . Phys. Rev. E49. R1353, (1994).

Koplik, J. and Banavar. J.R. Fluid cusps at the molecular scale. Fluids, vol. 6, 480 (1994).

Koplik, J., Banavar, J.R. Continuum deductions from molecular hydrodynamics. Annual Reviews of Fluid Mechanics.

Ma, W.-J., lyer, L.K., Vishveshwara, S., Koplik, J. and Banavar, J.R. Molecular dynamics studies of systems of confined

dumbell moleculles. Phys. Rev. E.

Ma, W.-J.. Keblinski, P.. Maritan, A., Koplik, J. and Banavar, J.R. Composition waves in confined geometries. Phys.

Rev. E48, R2362. (1993).

Ma, W.-J., Keblinski, P., Maritan, A., Koplik, J.. and Banavar, J.R. Dynamical relaxation of the surface tension of

miscible phases. Phys. Rev. Lett., vol. 71, 3465 (1993).

ouui i ueooooII oI I ona! i aouoi uI I I I i oo! ooI I I ! oooou! a! oooouneuoI oI I |o Io oae! eooooI oai oIm! ! ooaooI I oI I oooeoooI ooooOl aeoI o;I ego ouue Ig1! ooool ! oa! I aI g! on go oo! I I aotg eiio ! oooI o! oI el I o oolull i ooOI oOI oI oOOII OeaOO! eOaeOoI oil O OOOoil oI ool e ol anI oenI enuo Ooi oI e! ai naO o

I1-401
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

nm|i_4!_j|i_|iisi_|!iii|!I_i_||i||ii|_m|i||ia|i_|_Ii_t_iii_i_DIii|i|!|!|i_I_iiIi!iiilIg|iI|iai_I|in|_n|_ii_i_I_iIs_!l_||i_i_||n_|_i_I_ng_|n_l_n_I|ii_;_|_|i_|_!i_|I||i_|i_|i_|_i_i_|_

Fluid Dynamics and Solidification of Metallic Melts (FDSMM)

PRINCIPALINVESTIGATOR:Prof. Jean N. Koster University of Colorado, Boulder

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this effort is to investigate surface tension-driven convective flow of low Prandd number melts,

e.g., metals, and their effect on the solid-liquid interlace. (The Prandtl number is the ratio of the kinematic

viscosity to the thermal diffusivity.) This will require flow visualization which will be achieved by using tracer

particles and a real time X-ray system. This research will focus on fluid physics phenomena of

surface-tension-driven flows in material processing. It is known that liquids for which Pr> 1 have different

underlying fluid physics than liquids for which Pr<<l. The research is focused on gallium melts.

TASK DESCRIPTION:

Progress toward achieving radiographic particle image velocimetry (RAPIV) of liquid metal convection has required

extensive technological development. The RAPIV will be used to obtain system t]ow velocity vector fields using

appropriate computational analysis. RAPIV has been used successfully to detect the solid-liquid interlace of

solidifying gallium and to observe tungsten particles in molten gallium.

Rectangular, two-dimensional test cell geometries fi)r the series of high temperature RAPIV experiments have been

chosen. Two aspect ratios (length:height) will be used: 4:1 and 1:1 (with unit integration depth). The 4:1 ratio is

the classical "Hurle" geometry which is used often for comparative numerical studies.

The Integrated Convection Apparatus and Rotating Undercarriage Support (ICARUS) is a higl:-temperature (up to

1,000°C) modular furnace capable of establishing any combination of vertical and horizontal gradients in test cells

of various geometries. This provides the capability to vector the gravity body force from 0 deg. (horizontal) to

90 deg. (vertical).

TASKSIGNIFICANCE:

Fluid physics is the foundation of material solidification. The primary purpose of this research is to develop a

unique research capability |br convective flow visualization of metallic and electronic melts during the solidification

process in real time. By observing the flow pattern of a liquid metal during solidification, knowledge will be gained

in understanding the solidification process. This knowledge c_m be used to build better processing facilities which

can produce metals and electronic materials with improved properties (e.g., yield strength and toughness).

For example, titanium is used in today's aircraft, but little is known about titanium solidification. The design

engineer uses a safety factor of 1.33 which causes the parts to be heavier than they need to be. If the solidification

process was better understood, the titanium parts would be lighter. This would reduce the aircraft weight, thereby

improving the fuel efficiency or allowing greater payload capacity.

PROGRESSDURING FY 1994:

The advanced research facility for liquid metal (Pr<< 1) flow visualization using an X-ray system and high

temperature furnace (up to 1000°C) has been built and tested. Gallium has been selected as the test material.

Visualization of the density field has been achieved with the X-ray system. A density change of 0.1% can be

detected and is enhanced using false coloring. A 10°C horizontal temperature gradient was imposed. The mottle is

obscuring some of the data; this problem is being addressed. Eventually, flow patterns will be observed using tracer

particles. The particles must exhibit good wetting characteristics, high X-ray absorption and be neutrally buoyant.

1I.-.402
The development of neutrally buoyant, chemically inert tracer particles with high radiographic absorptivity is

essential to the RAPIV project. A substantial ongoing portion of the development eftbrt has been directed toward

the design of the appropriate tracer particles: The particles are currently under development. The most promising

particles are glass particles coated with nickel with a final layer of gold. Testing is in progress.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 2 MS Degrees: 1

PhD Students: 0 PhD Degrees: 0

TASK INITIATION: 2/91 EXPIRATION: 7/95

PROJECT IDENTIFICATION: 962-24-00-33

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Campbell, T.A. and Koster, J.N. Visualization of liquid/solid interface morphologies in gallium subject to natural

convection. J. Cryst. Growth. 140, 414-425 (1994_.

Campbell. T.A. and Koster, N,N, Radioscopic visualization or indium antimonide growth by the vertical

bridgman-stockbarger technique. J, Cryst. Growth. ¢1994).

Campbell. T.A., Pool, R.E., and Koster. JN. Melting and solidification of a liquid metal at a vertical wall. AIAA,

94-0792, (1994).

Koster. J.N. and Junior, V, Natural convection in a miscibility gap model alloy. J1. Mater Synth. Proc., (1994).

Pool, R.E., and Koster. N.N. Visualization of density fields in liquid metals. Int. J1. Heat Mass Transfer, (1994).

Prakash. A. and Koster. NN Convection in a liquid B203 encapsulated GaAs melt. Int. J1. Heat Fluid Flow, (1994).

_|_|_|_|_!_||_!_!_|_!!_'_'_!_|_'_!_|_|_|_|_!_!!_|_I_|_|_!!!_!_!_|_|_|_|_||_!_|_||_|_|_|_|_!_|_!_|_||_v_

11403
Thermocapillary Convection in Floating Zones under Simulated Reduced Gravity

PRINCIPALINVESTIGATOR:Prof. Sindo Kou University of Wisconsin, Madison

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The main objective of the research is to enable comparison between calculated and observed patterns of

thermocapillary convection in floating zones, regardless of whether or not the zones are cylindrical in shape.

Ground-based flow visualization experiments will be conducted under simulated reduced-gravity conditions, i.e.,

where thermocapillary convection dominates over natural convection just as in microgravity. This will include

silicone-oil zones and molten zones in NaNO3 rods. Computer simulation of thermocapillary convection will be

conducted and the calculated results will be compared with those observed in flow visualization.

TASK DESCRIPTION:

A mathematical formulation will be used to quantitatively describe the optical distortions. This formulation allows

the calculated flow patterns and solid/liquid intertaces to be converted into distorted ones so that they can be

compared directly with those observed in flow visualization to verity the validity of computer simulation.

Conversely, it can also be used to convert the observed flow pattems and solid/liquid interlaces into undistorted

ones.

TASK SIGNIFICANCE:

Comparisons between calculated and observed patterns of thermocapillary convection in floating zones, though

significant, have been rare (if perlbrmed at all), due to complications from optical distortions caused by the lens

effect of the floating zones. With the numerical tool, thermocapillary flows in floating zone configurations can be

more deeply understood. The capability of prediction can help the design of process of the active control, thus the

quality of the material and medicine will be improved.

PROGRESSDURINGFY 1994:

1. The velocity field in a silicone oil zone was measured using a laser light-cut technique and an optical chopper.

2. The velcoity field in a molten zone in a sodium nitrate rod was measured in the same manner.

3. The velocity fields were calculated by computer simulation.

4. The comparison between the calculated and the observed results was very good. It was demonstrated that without

taking into account the lens effect of the floating zones, the calculated and the observed results can differ from each

other significantly.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 12/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-00-46

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 2

I 1111111 | II i ii I II I I I i i I i i I I Ill I III lll Ill I I I I I II I III I I I I I I II I I I I I I I 111 II 1111I I lll lie lII l IO I I I II Ill I I I I II l I I lll I |ll Ill Ill I II I ;I l I II III I I I Ill I llll I I Oil I lie III II I Ill Ill Ill IIllll t I I III I II I I! I I Oll III I I I I I I eI i i l i ii ii Ill I I1 It tIll I II Itl III III I |l I |l I I I II

11-404
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

J u u l a 4o i u a u a o i o o n o oo ! o o i a o i n o | u mo ti o ia o i e o n i u mi a o ! u o ia a o i i o o a I I i i o i na muI I o o I a o o a o n i oI a | n a o o a o Io o ! o o a o I oo In g i a o J n i i no J ni J a | n i o I i o i o a o f Io o In | o a | o I o o o I | I I a o o io J Iol J n | J a o | n a I I a I 111 | I a a I u i | a III uo I ua n a mn a o a a o o I ul I ao u a o o | o i mn o n un na ! u i i I I u o I a o I no mn, I

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Lan, C.W., and Kou, S. Radial dopant ,,egregation in zero-gravity fioating-zmm crvstal growth. ,I. Cryst, Growth, vol.

132. 578-591 (1993).

Lan, C.W. and Kou, S. Formulation for cmTecting optical distortions due to a transparent floating zone. J. Cryst. Growth.

vol. 132, 471-471 (1993).

Lan, C.W. and Kou, S. Effect of rotation on radial dopant segregation in microgravity floating-zone crystal growth. J.

Cryst. Growth, vol. 133. 309-311 (1993).

Tao, Y.W. and Kou, S. Flow Visualization in floating-zone crystal growth. J. Cryst. Growth. vol. 137. 72-76 (1994).

ii on aI!IOIIIIII!I IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIiiii1*1111111111111111111111111111 IIIIIIlInlllllllllllllllllllllllllllllllllllllll iiiiiii1,11 iiiiiiiii i i iiiiiiiii iii i iii ii iiiiii i iii itl ii i itl iii iii iii iii iii i,1 i,11,1 i!1 i

11405
Analysis of Phase Distribution Phenomena in Microgravity Environments

PRINCIPALINVESTIGATOR:Prof. Richard T. Lahey Rensselaer Polytechnic Institute

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to map the void distribution throughout the tube cross-sectional area in two-phase

flows. The principal flow patterns to be studied are the bubbly and slug-flow regimes.

TASK DESCRIPTION:

The research approach is to conduct normal gravity testing using equal density simulation experiments. Normal

gravity experimental data, as well as available microgravity data, will be used to verify computational fluid dynamic

models that are being developed. Two types of equal density simulations will be used: liquid with solid spheres,

and a pair of immiscible liquids.

TASK SIGNIFICANCE:

The orientation of the phases with respect to each other and the tube wall al'fects the heat transfer characteristics and

the work required to pump the two-phase mixture. Terrestrial applications include the nuclear, electric power and

oil industries.

PROGRESSDURINGFY 1994:

Data acquisition and processing has been completed for testing with a water/polysterene mixture (liquid - neutral

buoyant particles). The radial distributions of the following measurements were obtained: average liquid velocity,

average particle velocity, turbulent intensities for the liquid and the particles, and the particle volume fraction. The

relative velocity between phases were close to zero, which is in disagreement with the microgravity data published

by Dr. Jean Fabre from the Institute de Mecanique des Fluides in Toulouse, France. After Dr. Fabre was contacted,

and the data was reviewed, Dr. Fabre acknowledged that the relative velocity was also close to zero for his tests.

Other results are as follows: the turbulence intensities of both phases are about the same. The particle volume

fraction has a maximum at the tube centerline and decreases towards the tube wall. This is opposite to the behavior

of liquid/vapor mixtures flowing upwards in normal gravity conditions, where the vapor phase accumulates close to

the wall and is dangerous for high heat flux diabatic flows. Fortunately, based on these results the vapor is not

expected to accumulate near the wall under microgravity conditions.

The three-dimensional, two-fluid conservation equations (i.e., mass, momentum, and energy balances) and the

closure laws using ensemble averaging for the liquid - particle mixture have been derived. The model includes a

consistent treatment of the interaction between the liquid turbulence and the particles, the collisions among particles

and collisions between the particles and the wall. The solution of the conservation laws has been numerically

computed using a CFD finite volume technique (Phoenics). The numerical results agree remarkably well with the

experiments without the adjustment and any coefficient.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 12/92 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-24-00-72

RESPONSIBLECENTER: LeRC

I I l aoill I Io l iOl I l i I i Oi i i iI II I OI I OOOOOlI I l l I Ol I l It ao II OOOOOI OI OI I I IOOI l noOOOOl OUl tl O Ill Ill I OOI Ol l II I Ol OI I II I I lal II l |! l I i l Ull iI Ill OII Ill O Ill I I l III Ill OIll I O OOI Oil ill oii i i i oi i oooOi oi i ol i ol Oil ill ill ill Itl ill lii o i ioI tllllll lOOltOI loll OOi i I I i O ill ii i

I1-406
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

oll. m_I_i_l_**l_i_"_"_"i_*I_i_"_"_*I"il*i"_"i_*_o_m*_"_I_o**o_n_"_n_H_*_H_**_n|_n_H_i_*_Hl_u_oi_I_n_I_ ii. i.II.l.ll.l*olalnl.l.llo_l*l.I.

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Lahey. R. and Bonetto. F. "Analysis _)I phase distribution phenomena in microgravity environments/' presented at

Second Microgravity Fluids C_mference in Cleveland, OH, June 21-23, 1994.

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II.-407
Nonlinear Drop Dynamics and Chaotic Phenomena

PRINCIPALINVESTIGATOR:Dr. L. O. Leal University of California, Santa Barbara

CO-INVESTIGATORS:

E.H. Trinh Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

The general objective of this collaborative experimental and theoretic',.d project is to explore nonlinear phenomena

associated with acoustic and/or electrostatic levitation of drops or gas bubbles in air or a viscous fluid. These

include both phenomena intrinsic m large amplitude oscillations of shape (or volume, in the case of gas bubbles),

and phenomena that are a consequence of the levitation process. In the former category, we include studies of newly

discovered coupling between shape modes and volume oscillations for gas bubbles, and oscillations of non-spherical

uncharged and charged drops in electric fiel&s, and in combined acoustic and electric fields. When experiments aimed

at understanding or exploring these fundmnental, intrinsic phenomena are carried out in an acoustic field, which may

be either steady or time modulated, there can be strong coupling between the bubble or drop position or shape, and

the acoustic levitation force, which can lead to additionai nonlinear oscillatory, phenomena that can be difl]cult to

separate from the intrinsic phenomena of interest.

TASK DESCRIPTION:

Following earlier work based upon small deformation asymptotics, coupled with a nonlinear dynamics analysis of

the weakly nonlinear amplitude equations, current theoretical work is focused upon numerical solutions lot finite

delbrmations of shape. Our most recent work has considered an inviscid drop (charged or uncharged) in a steady or

time-dependent electric field. We utilize the well-known boundary integral technique tbr this case, but we have "also

developed both full finite-difference and spectral techniques to solve tree boundary problems with viscous effects.

Experimental studies have utilized ground-based levitation systems located at JPL. These include both acoustic

levitation for small gas bubbles, and a combination of acoustic and electrostatic levitation lbr viscous drops in air.

The latter is particularly interesting because it allows compensation for the mean deformation associated with the

levitation process, so that the mean drop shape is spherical.

TASK SIGNIFICANCE:

We have worked on nonlinear dynamical effects due to trine-dependent torcing, and/or an initial detbrmauon for both

gas bubbles and viscous drops. These problems are important both from a fundamental point of view as a concrete

and accessible physical system which exhibits many of the classical nonlinear phenomena, but 'also because the

problems being studied have significant application to phenomena m multiphase flow. The work on gas bubbles

has yielded a fundamentally new understanding of forced or tree volume oscillations in the sense that we have shown

that purely radial oscillations, without change of shape, is an exceptionai phenomena. The generic behavior is that

there is an exchange of energy between volume (radial) and shape modes, which becomes extremely strong near

resonance. Current numerical and experimental work is aimed at understanding large amplitude effects, including

conditions that may lead to sufficiently large oscillations of shape that the bubble breaks. Bubble breakup due to

time-dependent fluctuations of an isotropic background pressure has not been investigated previously as a

mechanism tbr breakup, insofar as we are aware.

The dynamics of viscous drops in an acoustic or electrostatic levitator was originally studied in the microgravity

program of NASA primarily because it was viewed as the basis for containerless materials processing applications.

Although this is no longer a major priority, the fundamental problem is still one of considerable interest, especially

as a model system for understanding drop dynamics in electric fields tor applications ranging from meteorology

(raindrops) to ink-jet printers. There is "also a growing interest in the possibility of using time-dependent droplet

motions as a basis for measurement of material properties of the liquid or interface at extreme conditions of

_eiiui_*_o_u_Q_D_i_I_u_ut_ut_t_I_o_1I_t_u_IB_o_H_o_*_BH_nuID_*_eIInI_Iu_n_D_*_*_1_n_nIn_I_D_I_n_n_n_u_j_1*_

11-408
temperature. Finally, as with the bubble, the oscillating drop offers a convenient laboratory system to continue to

improve our understanding of the theory of nonlinear systems.

PROGRESSDURINGFY 1994:

The experimental eftort in FY 94 has concentrated on four separate tasks: (l) the study of large amplitude shape

oscillations of ultrasonically levitated drops in a time-varying electric field; (2) the investigation of large amplitude

shape oscillations of large bubbles ultrasonically trapped at reduced hydrostatic pressure; (3) the analysis of mode

coupling for nonlinear oscillations of drops levitated in air and drops and bubbles levitated in a liquid medium: and

(4) the investigation of large amplitude capillary waves on levitated thin liquid shells.

1. Oscillations of non-spherical uncharged and charged drops ultrasonically levitated in atr and in the presence of a

constant or time varying electric field have been quantitatively investigated. A soft nonlinearity has been measured

for the tun 'damental mode of shape oscillation, sub-harmonic resonant excitation of the fun "damental 1=2 and the

next higher mode 1=3 has been discovered, hysteresis in the large amplitude response of the fun 'damental mode has

been documented, and anomalous tree decay frequencies for drops driven into the higher resonant modes have been

ob_rved.

2. Air bubbles up to 5 mm in diameter have been trapped in 1 g in an ultrasonic standing wave at 22 kHz and at a

hydrostatic pressure reduced to about 0.3 atmosphere. Shape oscillations have been excited for various resonant

modes described by spherical harmonic expansion. For the water and air combination, shape modes up to I=5 can

be excited to macroscopic amplitude. No observation of coupling to the radial mode has been possible due to the

cavitation onset in the host liquid due to the high intensity acoustics required for trapping the bubbles in 1 G. An

approach for a microgravity experiment to investigate this radial to shape coupling is being developed.

3. Digital video analysis of shape oscillations of drops and bubbles in a liquid has been used to investigate the

resonant mode coupling of driven and freely decaying oscillations. For drops, direct coupling between the 1=6 and

1=3 axisymmetric modes has been observed for ultrasonically driven oscillations. Similar coupling between the

axisymmetric 1=4 and 1=2 non-axisymmetric modes has been documented. Coupling between the tirst four

resonant modes of freely decaying bubbles has been quantitatively measured through spherical harmonics expansion

of the observed oscillations.

4. The observation of the optically scattered signal from a levitated liquid shell has been used to characterize the

evolution of large amplitude acoustically-induced capillary waves. An interpretation of the power spectrum of the

waves has been attempted using the interaction of symmetric and antisymmetric waves on the shell. High speed

video observation has revealed a highly turbulent shell surface corresponding to a continuous frequency spectrum

prior to the bursting of the shell.

The theoretical effort in FY 94 has been focused on three specific directions:

(1) Application of our numerical boundary-integral code to study the problem of an electrostatically levitated drop in

a gravitational field, where both the charge Q and the electric field strength E must be nonzero. We are concerned

with steady shapes in steady E fields, oscillation frequencies for perturbed initial shapes as a function of E and Q,

and the response to time-dependent electric fields, among other issues. This work is currently being prepared for

publication.

(2) Re-exanunation of the problem of instabilities in the position of particles, bubbles or drops due to coupling

with the acoustic field in levitation. We have specifically been studying the computation of acoustic pressure forces

and fields when a body undergoes large (or at least not small) changes in position or shape. This has led to a new

formulation of the instability of position first studied theoretically by Rudnick and Barmatz (J. Acoust. Soc. Am.

87 (1), 81 (1990)). It is also the basis for numerical computations of time-dependent position and/or shape in an

acoustic pressure field.

11-409
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

i u i | a* | a a I I u o I a I o I o o mlo oa * I o * Iull II Iu _ n IIi I _ I | * Iu t n i t n a o | t | o I o o oo o n ; On u I J a Oo IOo Io On a | m OI OOI I* I OOI o I t a 41 a Ouo Oo a * OI Ot I OOa OOOOt I OI i i | n n o no On I * n a * * t OOI u *o I * OI n J i i o i a i i a oe t I* i a OOi | * * _ OOOOtOO* t ; OO; t n I OOI * OOOO_ a OI I o I a a i uo i | o i OOOa | ao Oi o t I Ot a OOIOOa 0 H

(3) We have continued to work on numerical simulations of finite amplitude coupling of shape and volume for a gas

bubble in steady and time-dependent pressure fields in support of the corresponding experimental studies.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 12/91 EXPIRATION: 11/94

PROJECT IDENTIFICATION: 963-24-07-01

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Feng, Z.C. and Leal, L.G. On energy transfer in resonant bubble oscillations. Physics of Fluids, 5 (4), 826-836 (1993).

Feng, Z.C. and Leal. L.G. Bifurcation and chaos in shape and volume oscillations of a periodically driven bubble with

two-to-one internal resonance. J Fluid Mech, Vol. 266, 209-242 (1994).

Holt, R.G.. and E. H. Trinh.

(1994).

Resonance effects in axisymmetric forced bubble oscillations. J. Acoust. Soc, Am. 95, 2938

Holt, R.G., and E. H. Trinh. Radiation pressure-induced capillary waves. J. Acoust. Soc. Am, 95, 2939 (1994).

Yang, S.M, Feng, Z.C and Leal, L.G. Nonlinear Effects in the Dynamics of Shape and Volume Oscillations for a Gas

Bubble in an External Flow. J. Fluid Mechanics, 247, 417-454 (1993).

Presentations

Trinh, E.H., L. G. LeaJ, Z. C. Feng, and R. G. Holt. "Nonlinear dynamics of drops and bubbles and chaotic phenomena."

Second Microgravity Fluid Physics Conference, June 1994, Cleveland, Ohio.

Trinh, E.H., R. G. Holt and D. B. Thiessen. "Nonlinear dynamics of non-spherical levitated drops: An experimental

study." APS-DFD Meeting, Atlanta, GA. November 1994.

__________________u__________________________________________oooo__________I_!II________________oo___o__o_o__I__________tog____|__I__no_o___ I IllIllllUllllOllllOOUllll!OlOlOllllllllltlIOtlllnetlelllllttlt II IIIIIIIIOIIIIIIIIIIIIIIIIIIIIIIIIIOIOII

11--4 I0
Oscillatory Cross-Flow Electrophoresis: Application to Production Scale Separations

PRINCIPALINVESTIGATOR: Dr. David T. Leighton University of Notre Dame

GO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The task objective primarily conststs of an experimental verification of the expected performance of an oscillatory

cross-flow binary separation device. This device is designed to use an oscillatory electric field across the narrow gap

of a specially designed electrophoresis channel to cause species with different electrophoretic mobilities to have

different time / location histories within the gap. This oscillatory motion is coupled with an oscillatory fluid

cross-flow to achieve rapid separation of molecules based on their electrophoretic mobilities. The system acts as a

semi-permeable barrier, actively transF)rting molecules with mobilities either greater or lower than some adjustable

value across the cell, while rejecting 'all others. Because the throughput is largely governed by the amplitude of the

oscillatory cross-tlow, protein throughputs several orders of magnitude greater that those in conventional

continuous tiee-flow electrophoresis devices are theoretically achievable.

TASK DESCRIPTION:

Initially, the design for the oscillatory cross-flow binary, separation device will be finalized and the device itself

constructed. After construction of the device, its performance will be first qualitatively tested using the dyes phenol

red and naphthol green B. As the amplitude of the electric field is changed, the dyes will be selectively "allowed to

pass through the separation cell from one reservoir to another. Subsequently, quantitative measurements of the

separation achieved by the device will be made using the proteins cytochrome-C, 'albumin and thyroglobulin. These

readily available proteins can be analyzed using HPLC equipment available to the PI at the Center for

Bioengineering and Pollution Control at the University of Notre Dame. Concurrent with the experimental studies,

we will 'also conduct simulations {}tthe device to investigate end effect.,;, finite concentration effects, and the

influence of more general electric fields and oscillatory cross-flows. It is hoped that these investigations will allow

us to optimize the device and further improve the selectivity and throughput.

TASK SIGNIFICANCE:

Because the amplitude of the throughput is largely controlled by the amplitude of the fluid motion and only

indirectly by the electrophoretic mobility, the throughput of this device is potentially several orders of magnitude

greater than conventional free-flow electrophoresis devices. Expertmentai verification of the theoretical concepts

underlying the proposed device are crucial, however. The research program is designed to 1) provide such

verification and 2) to further optunize the system.

PROGRESSDURING FY 1994:

The initial funds for this project were only awarded during the final month of FY94, thus progress to date has been

limited. Currently we are in the process of selecting a graduate student to work on the project and finalizing the

design of the electrophoresis cell to enable construction

STUDENTSFUNDEDUNDER RESEARCH: TASKINITIATION: 9/94 EXPIRATION: 9/96

PROJECTIDENTIFICATION:962-24-08-16

NASA CONTRACTNO.:NAGS-1080

RESPONSIBLECENTER: MSFC

IIIIIfIIIIIIIfIIIIIII IfIIfIIIIIIIIIfIIIIIIIIIIIIIIIIIIIfIIIIIIIIIIIIIIIIIIIIIIIII III IIIIIIIII IIIIIII IIIIIIIfIIIfIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIII IIIIIIIIIIIIIIII IIIIIIIIIIIIIIIfIIIIIIIIIIIIIIBIfIIIIiI IIIIIIfIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIfII

11-411
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

i i i i i i i | i ii i| J i n i n Mi i | i i i ii ii i | i i |H i i i t i i i i I i II _ I i i i t n i i i i i i i a o o i! o i i a i i i I I _ n iii i i i i i i n I n i o !i i I i i i i I I I i | ii i ii i i i i ! i | ! 0 | |i i | i o o I I i | i I i i i * | I iI ! I i i i i i i o i i Di ii i i t i i i o t i i I |i i II i i I I I I | i i i _i i ! I I i i | i i i I_ i i i | i i t i | | i i i I ii | ii i i i i i n i i n | i ii n i i n i i | i i i i! _ ii i

Low Dhnensional Models for Thermocapillary Convective Flows in Crystal Growth Processes

PRINCIPAL INVESTIGATOR: Prof. A. Liakopoulos Lehigh University

CO-INVESTIGATORS:

Prof. P.A. Blythe Lehigh University

TASK OBJECTIVE:

The objective of this work is to construct and validate low dimensional dynamical models of surface tension driven

flows that are relevant to crystal growth processes. The models will be used to study process stability and the use

of reduced-order models for control schemes.

TASK DESCRIPTION:

A data base of 2-D, axisymmetric, and 3-D numerical solutions of the full nonlinear governing equations will be

constructed using spectral element methods. These simulations are based on a variation formulation for unsteady

viscous flow and an Arbitrary-Lagrangian-Eulerian description. The Karhunen-Loeve, K-L, procedure is used to

determine spatial structures of the computed flow and thermal fields. Coupling of the K-L procedure with the

method of weighted residuals tor the full models will yield a low-dimensional representation of the flow system.

TASK SIGNIFICANCE:

r

Reduced-o_er models make feasible stability and bifurcation calculations tot thermocapiUary flows of practical

interest. Fdrthermore, they can provide the basis for designing model predictive controllers tor the suppression of

instabilities that occur during crystal growth processes in a microgravity environment.

PROGRESSDURINGFY 1994:

In the first three months, research has been directed toward the following tasks:

1. Collection of data from direct numerical simulations of thermocapillary flows in rectangular cavities.

All simulations are time accurate. If a steady (time-independen0 solution exists it is found as the steady-state

solution of the appropriate initial boundary value problem al'ter all transients die out. In all cases, the flexibility of

the free surface is fully incorporated into the mathematical model. Two configurations are under investigation: a)

differentially heated open cavities of aspect ratio (width/height) A=1,2,4 and, b) open shallow cavities with spatially

periodic temperature distribution imposed on the tree surface. In case (b), the governing equations are solved in a

computational domain consisting of a single module with periodic boun 'dary conditions on the side boundaries.

2. Development of computational tools needed for the Karhunen - Loeve decomposition (POD) of 2-D and 3-D

oscillatory convective flows and the construction of low-dimensional dynamical models.

The POD methodology has been applied successfully to thermal convection flow in a channel with discrete,

spatially periodic heaters. A dynamical model consisting of six ordinary differential equations has been derived by

using the empirical eigenfunctions as basis functions in a Galerkin expansion. The stability and bifurcation

characteristics of the reduced-order dynamical system are under investigation.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-24-00-88

RESPONSIBLECENTER: LcRC

IS lie lllleel ill lell llll Ill Ill IIIIIII nlllll Iii nl lU III III III III I II I III II I II III IIIIII I IIIII III IIi III III I I I III III iiiiii III IIII III III IIII III III III IIIIIII III I II III III III I II III III III II I III III III I I I III III III IIII III II I III I ii I II iI I II I III I III III III ii i i

11412
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

Absolute and Convective Instability of a Liquid let at Micro_ravity

PRINCIPALINVESTIGATOR: Prof. Sung P. Lm Clarkson University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective is to establish a definite role of capillary, viscous, and inertial lorces in the absence of gravity by

using the fluid dynamics problem of the stability of a liquid jet as a vehicle. The objective will be achieved by

re-examining the known theories that can be verified completely only in microgravity. A wide range of Weber and

Reynolds numbers will be studied, and any unexpected phenomena in microgravity that may require a new

interpretation of dynamic capillary force will be examined.

TASK DESCRIPTION:

The results of the proposed work will provide some benchmark knowledge in fluid dymunics. When the resulL_

obtmned at microgravity are compared with the known theories for 0-g and with the known experimental results

obtained at l-g, one will be able to untunbiguously assess the significance of gravitauonal and inertial fl_rces

relative to the capillary force over a wide range of dynamic flow parameters. The original approach was to design a

rig to conduct one-g experimenLs during the first year (1993). The approach now, however, is to design and

fabricate a rig able to conduct both low-g and one-g liquid jet experiments. Numerical modeling and dr',dt rig

designs have been accomplished during the l_st two years. Ground-based Iow-g experiments will take place during

the second year in the LeRC 2.2-Second Drop Tower. Companion one-g experiments with the same rig will be

done at the PI's university. Data analysis and flight experiment definition is tentatively planned ti}r the third year.

TASK SIGNIFICANCE:

From a practical view point, the knowledge gained on the precise mechanisms of various modes of jet breakup will

allow one to improve many existing importmlt industrial processes. These processes include film coatings,

combustion of liquid fuel, and formation of various chemical sprays. Improvements of the efficiency of these

processes "also bring about a drastic reduction in environmental pollution. The knowledge may also be exploited for

advanced material processing.

PROGRESSDURINGFY 1994:

The theoretical work continued in the investigation of absolute and convective instability of a viscous liquid jet

emanating into a gas. As previously reported, this analysis was done over a parameter space spanned by the

Reynolds, Froude, and Weber numbers; as well as various viscosity, density, and diameter ratios. The work

continued to demonstrate that the reduction in gravity tended to enhance the Rayleigh mode of convective instability

(i.e, where the liquid jet breaks up into drops of dian}eter comparable with the jet diameter). Whereas, the Taylor

mode of convective instability (i.e., where jet atomization occurs) is retarded at reduced gravity.

Systems modifications continued this fiscal year in the build up of an experiment rig suitable for the LeRC Drop

Tower. Special attention was paid in the design of the electronic components. These components include the

function generator and the amplifier. The design and construction is on-going; subsequently, one-g tests have not

been done yet. They will be accomplished when the Drop Tower rig has been completed so that both one-g and

Iow-g testing can be done by the same set of hardware. Component position determination and functional testing of

the hardware is now on-going at Clarkson on a Drop Tower rig that had been sent to them. It is expected that final

rig design and build-up, as well as one-g and low-g testing will occur within the early 1995.

!I--413
If. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 1

TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-00-47

RESPONSIBLECENTER: LeRC

BIBLIOGR#PHIC CITATIONS FOR FY 1994:

Journals

Lin. S.P. and Webb, R. Nonaxisymmetric evanescent waves in a viscous liquid jet. Physics of Fluids. 6, 2545-2547 (July,

1994).

Lin, S.P. and Webb, R.D. A branching liquid jet, Physics of Fluids, 6 2671-2675 (August 1994).

Presentations

Lin, S.P. "The breakup of a liquid jet at microgravity." (AIAA 94-0833 32nd AIAA Aerospace Sciences Meeting, Reno.

Nevada, January 10-13, 1994.

I i |i I |I I I ! I I I I I I _i II e Ii I I |11 ! i |111111111 | I | | | | i| I |1 | | | | I| | I| | i | I I I eI I I I I| I I| I | I I I I | I I I II I I! | || I | ! I ! !I II | _! I | I I | ! _I |I I | | I I I I I I I I _Ill I I I I I I | I Ie I II I | I | ! I I I ! | I I| II I I I I III I II II I ! | _I I I I I I I I II II eI I I I i i I II II I I I | I I I I I I I I !* II i i | I I I II i | i | I | | II i i I I _I I I | II I

11--414
Magnetorheological Fluids in Microxravity

PRINCIPALINVESTIGATOR: Prof. Jmg Liu California State University, Long Beach

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

This research investigates experimentally the influence of gravity in the formation of the equilibrium structure of

magnetorheological fluids.

TASK DESCRIPTION:

Magnetorheological (MR) fluids are colloidal suspensions whose theological properties can be varied through the

application of an external magnetic field. The key to this modification is the structure induced in the particles of

the suspension. This work seeks a better understanding of the equilibrium structures and the influence of gravity to

ik_ formation, dynamics of MR fluids, and therefore, the interaction mechanism. This effort will start by

identifying the fluids equilibrium structure, characterizing it, and then examining the parameters controlling its

tormation, including the rate of the applied magnetic field and the effect of gravitational settling. The basic

experimental techniques for this work will be static laser light scattering and optical microscopic imaging.

TASK SIGNIFICANCE:

This research will help us to understand the basic physics of a liquid to a solid phase transition of this so called

"smart" material under the application of an external field. It will additionally provide guidelines for making

technologically important materials of the magnetorheological fluids in general. For example, this material can be

used in automobiles as shock absorbers, clutch controls, robotic joint controls, etc., due to the viscosity change

controlled by the field. In order to do so, however, we must understand and design them better.

PROGRESSDURING FY 1994:

Martin Hagenbuchle, a postdoc from the University of Kunstanz, Germany, was hired to work on this project.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION:962-24-05-90

NASA CONTRACT NO,:NAG3-1634

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Liu, J., Lawrence, E.M., Ivey, J.L., Flores. G.A., Bibette, J. and Richard, J. Field-Induced structure of confined ferrofluid

emulsion. J. Mod. Phys. B., (1993).

Liu, J.. Lawrence, E.M., Wu, A., lvey, M.L., Flores, G.A., Javier, K.A., Bibette, J. and Richard, J. Field-Induced structure

of ferrofluid emulsion. Submitted in May, (1994).

Liu, J., Mou, T., Flores, G.A., Bibette, J., and Richard, J. The evolution of field-induced structure of confined ferrofluid

emulsions. Proc. 4th Int. Conf. on electrorheological fluids, Feldkirch, Austria, (July 19-24, 1993).

Proceedings

Liu, J. "Dynamics of field-induced structure in monodisperse magneto-emulsions." Gordon Converence on

Macromolecular and Electrolyte Solutions, Oxnord. CA, February 6-11, 1994.

I I I I I II I I I II I I I I I I I I i I I I I II I II I *11 II I I* I I I i i i i i i i Ii i I I I I I I I i i iI ii i i i i i i i ii i J I I I I I I I I I II I I I I I I I I I i ii i I I I I I JI I I I l II * II I I I * I I * III I I I I i i i I I I I I I I *11111111111111111111 II I ii i I II I I I I I II I I I II I I I I I I I I iI I I I I I I * I I I I I I I I I I JI I II * I I I I I I I II II I I I I I I I i iI II I I I I I I

11--4 1 5
'7

II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

nlJlon.ln_llo..nlelotlo.a_|lJoalo_oollol.l.nolllinotlq0au Èn"n_"_i_H_n_on"_H_j|_Il_u_|_ji_"i|tl_Il_n_"_"i_|Hlr .tlol.lll|uInam o aao01.1.a.1ollolalna.1oolaonullaoJ.luollolnoon.a-l.u-aLiu, J. "Structure study of monodisperse magnetu-emulsions." II Int. Conf. on Static and Dynamic Light Scattering,

Fehmer. Germany, February, 1993.

Presentations

Liu. J. "Field-induced structure of confined monodisperse ferrofluid emulsions." APS, Pittsburgh, PA. March. 1994.

Liu. J. "Evolution of field-induced structure of confined monodisperse ferrofluid emulsions." APS. Pittsburgh, PA, March.

1994.

Liu, J. "Magnetic-field-induced structure of monodisperse magneto-emulsions." Gordon conference on Macromolecular

and Electrolyte Solutions, Oxnord, CA, February 6-11. 1994.

Liu, J. "Dynamics of field-induced structure in monodisperse magneto-emulsions." Gordon Converence on

Macromolecular and Electrolyte Solutions, Oxnord, CA. February 6-11. 1994.

Liu, J. "Magnetic-field-induced structure of monodisperse magneto-emulsions." 4th Int. Conf. on Electrorheological

Fluids, Feldkirch, Austria. July 19-24, 1993.

Liu, J. "Structure study of monodisperse magneto-emulsions." II Int. Conf. on Static and Dynamic Light Scattering,

Fehmar, German, February, 1993.

Liu, J., "Dynamics of field-induced structure in monodisperse magneto-emulsions." 4th Int. Conf. on Electrorheological

Fluids, Feldkirch, Austria, July 19-24, 1993.

Liu, J., Lawrence, E.M., Iey, M.L., Flores, G.A., Bibette. J.. _md Richard, J. "Field-Induced structure of confined ferrofluid

emulsion." Proc. 4th Int. Cony. on Electrorheological fluids, Feldkirch. Austria, July 19-24, 1993.

ao!o_ooo_!_i_lol!e!oo_e_uoo_nnlneloll_u_o_o!_oeu|_qu_o_eo_o!el!e_!o_!all|!_!!o_l_o|_o!_ooeeoe_e;!ol_oD_a_!_o!eo!o_o|oo_o_"_leo_e|_o_o_bo!_|le_o!elloo|oI_ooq_|a_!l_|IonIa_n|le_|oo|;_lollo_!oo_oo|oe_*Do_|ooeo_|oo|_oo!!oa_|!_ooooo_Hou|_

11416
Cross Effects in Mtcrog-ravity Flows

PRINCIPALINVESTIGATOR:Prof. Sudarshan K. Loyabka University of Missouri, Columbia

CO-INVESTIGATORS:

Prof. R.V. Tompson University of Missouri, Columbia

TASK OBJECTIVE:

The research objectives are to:

1. Solve the Boltzmann and the Wang Chang Uhlenbeck equations to determine the flow rates (mass and heat) and

the matrix of the phenomenological coefficients, for arbitrary. Knudsen number (ratio of mean free path to

characteristic flow dimension), for arbitrary gas (vapor) mixtures, realistic intermolecular and gas-surface interaction

potentials, and for small (linear), as well as large (non-linear), gradients.

2. Verity the results by acquiring experimental data in a diffusion cell.

3. Explore applications of the results above to stmulations of flows in ampoules.

TASK DESCRIPTION:

The experimental apparatus will be designed to test the theoretical results. The classified diffusion two-bulb setup

with a connecting capillary will be used with the bulbs held at different temperatures. Results from the new

theoretical and experimental understandings will then be used to study flows in specific microgravity experiments

through discussions with the NASA scientists and engineers.

TASK SIGNIFICANCE:

Film growth by chemical/physic_ vapor deposition is a process of considerable interest in microgravity

experiments. The absence of natural convection should allow better control of the growth processes, but it has been

pointed out that in the highly nonisothermal ampoules, thermal slip (creep) can become a matter of significant

concern even for Knudsen numbers as small as 10L Thus, it is important to understand and control the flows that

arise from the molecular (rather than the mere continuum) nature of gases and vapors.

PROeRESSDURINeFY 1994:

The project personnel have to-date solved numerically the Boltzmann Equation for a monatomic gas tor rigid sphere

molecules and cylindrical geometry, under noncondensing conditions. All phenomenological coefficients have been

computed. Initial computations for realistic potentials (monatomic gas), and the velocity and the creep slip, have

been completed. The creep slip is found dependent of the type of gas, and results conl-trm accuracy ofrecendy

reported variational results. The variational technique 'also has been extended, and it has been shown that the planar

flows can be computed very efficiently, for all Knudsen numbers, by use of the Burner solutions. The diffusion

slip and the creep slip also have been computed for monatomic gas mixtures. The two bulb apparatus for

isothermal experiments has been designed, built, and tested. Experimental data on two gas mixtures (At-He, N2-He)

at several pressures (1 torr to 200 torr total pressure) and mole ratios have been obtained, and are found in good

agreement with the theoretical predictions (in the slip regime). Development of a Computer program to allow

simulation of deposition in cross flows in idealized geometries (cylindrical tube) has been successful. Ongoing and

planned research includes c',dcutations on mixtures lot arbitrary pressures, measurements with noncondensing and

condensing species (such as mercurous chloride) under temperature gradients, measurements of momentum

accommodation coefficients (that affect the flows) for gas mixtures, generalization of the computer program on

deposition in other geometries, and development of ideas for a space based experiment in the project area.

I I i i i i iI I I I I I i i i i i i ii ii eoi o| i o| oo I II | u i | i i | i i i i* i i| | i i i | | I I i I I | | ii I I i i | i i | i | | ii | i i | i | | i* I Ii I I oI I oI I |I I | i IIi | oI| |i | ! | I i i I I oI | ooI II I I oI | I I o| i i | i |oiII ! i I | I I I I i oI I| I II I I I I oI | I | I iii |i oi I I i * iI, bi i ! | o I II I I I I I I | i | | i || i | | I | | | | | ii |i I I i | oi i ooi |! i i i o| ! i | |

II--417
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 11-92 EXPIRATION: 11-95

PROJECT IDENTIFICATION: 962-24-00-64

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Ivchenko, I.N.. Loyalka, S.K., and Tompson, R.V.

Thermophysics of High Temp., (1994).

On the use of conservation laws in planer slip flows. J. of

Proceedings

Ivchenko. I.N., Loyalka, S.N., and Tompson, R.V. "A simplification of moment systems for curvilinear boundary."

Proceedings of the XIX Rarefied Gas Dynamics Symposium, Oxford, U.K., July, 1994.

Ivchenko, I.N., Loyalka, S.N., and Tompson. R.V. "The polynomial method for boundary problems of transfer in rarefied

gases." Proceedings of the XIX Rarefied Gas Dynamics Symposium, Oxford, U.K., July, 1994.

Thesis

Gabis, D.H. "Tangential momentum accommodation under transition flow." Ph.D. Thesis. University of

Missouri-Columbia, 1994.

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11418
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

n ll.llll;ll.l.tlllll!tl011111oll m_Ii_nj_jt_j_"_"_"_"_"_I_I_"_ii_I_li_;_II_i"i_i_;"_"I_;_"l_I_i"1It _.ll.llel"ll|lllllIll.l|llllll"l|lIHll01"tl"llH a0m.ll.lll|llllllJlllllllllllll;lllnSll .ll|ll.I

Controlling the Mobility ql: a Fluid Particle in Space by Using Remobilizing Surfactants

PRINCIPALINVESTIGATOR:Prof. Charles Maldarelli City University of New York

CO-INVESTIGATORS:

Prof. Demetrius Papageorgiou New Jersey Institute of Technology

TASK OBJECTIVE:

This research program studies theoretically and experimentally how to use surfactants to control the mobility of the

fluid interface of bubbles or drops moving through a continuous liquid phase. The interracial mobility determines

the drag exerted on the fluid particle as it is driven through the continuous phase. By controlling this mobility, the

steady translational velocity of the drop can be mampulated independent of the force causing the particle to move,

and this control may prove useful in material processing under microgravity which requires the management of

thermocapillary driven bubbles and drops.

TASK DESCRIPTION:

Surtactant affects tile inteffacial mobility by creating surface tension gradients which resist the inteffacial flow:

Surfactant molecules dissolved in either the continuous or drop phase kinetically adsorb from the bulk sublayer

adjoining the interlace onto the surface. Once adsorbed, the surfactant is convected by the surface flow to the

trailing pole of the particle. Accumulation at the back end causes kinetic desorption into the bulk sublayer; this

increases the sublayer concentration causing a diffusive flux of surfactant out into the bulk,. At the front end, the

kinetic adsorption depletes the sublayer, and forces a diffusive flux of surfactant from the bulk to the sublayer at the

front end. At steady state, diffusive, kinetic and convective fluxes balance, and a concentration gradient develops on

the surface with the trailing pole larger than the leading pole. Since suffactant reduces the interfacial tension in

proportion to its surface concentration, the leading pole is at a higher tension than the trailing pole. The leading

pole tugs at the trailing pole, and this tangential action opposes the surface flow and hinders the interracial

mobility.

To use this retardation mechanism to manipulate the interracial mobility, the kinetic and diffusive fluxes which

maintain the concentration difference across the fluid particle must be controlled. Diffusive fluxes can be controlled

by using bulk concentrations large enough to form surfactant aggregates; these aggregates act as sources of

surfactant monomer thereby reducing the diffusion gradients and increasing the interfacial mobility. Kinetic fluxes

are controlled by the kinetic exchange coefficient, which is determined by the surfactant structure. The overall goal

is to investigate both of these mechanisms.

TASK SIGNIFICANCE:

The results can be used to control thermocapiltary driven bubble motion, e.g., in a glass melt, and in miscibility

gap solidification of two phase composites. In each of these examples there is a need for controlling the

thermocapillary migration velocity. In the movement of gas bubbles in a melt, it is desired to have as large

migration as possible. In the case of miscibility gap solidification, the object is to reduce the migration velocity as

much as possible, so that phase separation does not occur.

PROGRESSDURING FY 1994:

The first effort has studied kinetic control; as described below, a creeping flow model has been constructed to

describe the effect of the kinetic rate constant on the fluid particle terminal velocity, and the kinetic rate has been

measured using the pendant bubble method for a polyethoxy surfactant.

A. Creeping Flow Model: Kinetic absorption from the sublayer of the fluid particle (assumed to be at the bulk

concentration) to the surface is described by a Langmuir kinetic rate equation. The interfacial mobility is controlled

II--419
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

i oo i i a n a * | a o o I I o I _ | i n ao o inln a | o | I o I I o * I aIII o | I o I _ g o I u t n a * I to o 11o I 111 ; III II a o I I * n n o n I J o no | I o n a o n a_ n uo | i o o H | $ mo ii o. J |1 *. J u o | oa o iI o o o | o i u o J i o n i n o i a on I n o I o o n o o I uo I Io n a i J o o | a i u I on noinn n no o n o|no o I * i n o | n a n na o i | a n I o I I o I I *o n n o n a | i a o i | in uo u i _ n I a o I a _

by' t,he ratio of the characteristic kinetic rate to the surface convective rate. This ratio is denoted by Bi. A creeping

flow hydrodynamic model has been constructed and solved by a weighted residual technique; the dependence of the

terminal velocity on Bi is given for a gas bubble and different values of the Marangoni number (Ma). The results

demonstrate that as the kinetic exchange increases relative to the convective rate (larger Bi)n the surface concentration

becomes more uniform, the interracial tension gradient force is reduced, and the terminal velocity mcreases. As

surfactant exchange becomes very slow, surfactant accumulates in a stagnant cap at the trailing pole. and the largest

retardation in the particle mobility is obtained.

B. Measurement of Surfactant Exchange Kinetics: To measure the kinetic exchange coefficient, the pendant bubble

technique enhanced by video image digitization is used. In this technique, a bubble is formed at the tip of a needle

immersed in a surfactant solution, and a video image of the bubble is used to determine the interlace contour and the

surface mnsion. Two types of experiments are undertaken. In the lhst, the pendant bubble is quickly created, and

surfactant diffuses towards and adsorbs onto the freshly created interlace, lowering the surface tension. The dynamic

surface tension relaxation is measured until equilibrium is achieved. In the second, the bubble is first allowed to

come to equilibrium, and is then quickly compressed, raising the surface concentration and reducing the tension.

Surfacumt desorbs off the surface and diffuses back in the bulk, increasing the surface tension. In this case, the

dynamic relaxation in surface tension back to the equilibrium value is measured. For each case, a mixed

kinetic/diffusive model to describe the suffactant transport is constructed, and a parametric fit of the relaxation data

determines the diffusion coefficient and rate constant.

The surfactant studied is a polyethoxylated amphiphile. Dynamic tension relaxation data lbr clean inter/ace

adsorption and re-equilibration for several values of the bulk concentration have been measured and compared with

the mixed model simulations. From the parametric fitting, values are established for the diffusion coefficient and

the kinetic absorption coefficient. The desorption rate constant to the adsorption constant is equal to 4.6x10-4

sec-l.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-24-05-90

NASA CONTRACT No,: NAG-1618

RESPONSIBLECENTER: LeRC

oo!oo!m_g_|a_o_||o_a|_ao_e_|ooaIon_logo_!an_|_ao_on_o_no_!u_oano_!_||_!_|_|_|_|_|_!_!_|_|_!|_!_||_!_!_!_!_ ion!ol!Ol!!llOlaU!Ollolnolalll OI!OilIIO!IOIIOOIO!IOlOIIIIIIOilOI

11-420
|I. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Stabilization and Low Frequency Oscillations qfi Capillary Bridc_es with Modulated Acoustic

Radiation Pressure

PRINCIPALINVESTIGATOR:Prof. Philip L. Marston Washington State University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objectives of this investigation are as follows:

1. Investigate the response of the liquid capillary, bridges to acoustic radiation pressure excitation.

2. Acoustic_flly suppress capillary breakup of long liquid bridges.

TASK DESCRIPTION:

Liquid bridges surrounded by another liquid will be studied in a modified Plateau tank apparatus. A candidate lluid

for the liquid bridge is a silicone-oil/tetrabromoethane mixture. The surrounding Iluid is a water bath. The bridge

length and location will be adjusted to investigate the mode coupling of the radiation pressure of the surrounding

ultrasonic field. The ultrasonic field will be mapped with a hydrophone. For dynarmc studies, the spatial and

temporal modulation of the radiation pressure will be used to selectively excite mode resonances. After deactivating

the transducers, mode frequency and rate of the free decay will be monitored optically. Static bridge shapes will then

be measured with CCD cameras attached to digitizers and a personal computer.

TASK SIGNIFICANCE:

The proposed research furthers the understanding of the dynamics of capillary bridges which can lead to improved

control of float-zone crystal growth processes. In addition, the research may also lead to an increase in dynamic

gravity tolerance levels lot liquid bridge related phenomena on the Shuttle.

PROGRESSDURINGFY 1994:

A system has been built for the deployment of neutrally buoyant bridges of a silicone-oil/tetrabromoethane mixture

in an ultr&sonically excited water bath. The equilibrium diameter of the bridge is fixed by the support but the bridge

length (and w)lume) may be adjusted. The amplitude of the ultrasonic field is modulated at low frequencies

representative of the natural frequencies of the bridge. By optically monitoring the response of the bridge while

scanning the modulation frequency and adjusting the bridge location, the desired ultrasonic excitation of bridge

modes has been demonstrated. Ultrasonic deformation of static bridges has also been observed. Additional studies

are underway to determine the natural frequencies as a function of bridge length for weakly 'damped modes. The

mode shapes and radiation pressure coupling are also being investigated.

STUDENTSFUNDEDUNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-91

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

11-421
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Marston. P.L.. Trinh, E.H.. Depew, J. and Asaki, TJ. Response of bubbles to ultrasonic radiation pressure: dynamics in

low gravity and shape oscillations. Dynamics and Interface Phenomena. J.R. Bale et al. (eds) (Kluwer. DordrechtL

343-353 (1994).

NASA Tech Briefs

Marston, P.L., Trinh, E.H., Depew, J. and Asaki, T.J. Oscillatory dynamics of single bubbles and agglomeration in a

sound field in microgravity, in Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity

Measurement Group, edited by N. Ramachandram D.O. Frazier, S.L. Lehoczky, and C.R. Baugher (NASA Conference

Publication 3171. Marshall Space Flight Center, AL. NASA Tech Brief. Vol 2, 673-690 (1994).

11-422
Study of Disturbances in Fluid-Fluid Flows in Open and Closed Systems

PRINCIPALINVESTIGATOR: Prof. Mark J. McCready University of Notre Dame

CO-INVESTIGATORS:

Prof. H-C Chang

Prof. D. Leighton

University of Notre Dtune

University of Notre Dtune

TASK OBJECTIVE:

The objective of this effort is to examine the different instabilities that can affect a liquid t-tim during gas-liquid

flow.

TASK DESCRIPTION;

A generalized approach is being undertaken for gas-liquid flow in an open channel with finite length, with or

without gravitational stabilization, as well as lor the analytically simpler case of liquid-liquid rotating flows. Either

gas-liquid low-gravity testing or comparison with existing low gravity data is planned.

TASK SIGNIFICANCE;

The presence of waves can enhance the heat transfer between phases but increase the energy required to pump the

phases through a pipe network. Terrestrial applications include the nuclear, electric power and oil industries.

PROGRESSDURING FY 1994:

The rotating matched-density liquid experiment has been run for a range of conditions where waves are present at the

interlace. The observed onset of waves agrees well with linear theory. Measurements of steady wave amplitudes

agree very will with predictions from the theory derived from a weakly-nonlinear simplification of the complete

Navier-Stokes equations and boundary conditions. This appears to be the first time that experimental verification

has been provided for finite amplitude theory lot an interfacial system. The wave shapes match almost exactly; and

the speeds, which differ slightly from linear theory, 'also agree with nonlinear theory. Nonlinear theory indicates

that the primary mechanism of stabilization of the unstable fundamental interfacial mode is by a quadratic

interaction with the interfacial overtone and internal modes. This occurs even though the system is not resonant.

Surprisingly, Couette flow differs from channel flow where a cubic self-interaction is dominant. The physic',d

reasons Ior this are being investigated.

Calculated wave shapes for a sheared gas-liquid flow reveal that if gravity is absent, the amplitude and speed are

greatly increased. Because atomization in annular flows occurs from the crests of large waves, these results suggest

that atomization in microgravity studies should be significantly greater than Earth studies. Hopefully, these

theoretical results can be verified by using existing interface tracing data from aircraft studies.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-05-55

MS Students: 1 MS Degrees: 1 RESPONSIBLECENTER: LeRC

PhD Students: 3 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Gallagher. C.. Kropnewicki, T. Leighton, D. and McCready, M. "Two-layer viscous instability in a rotating coutte

device." Presented at Second Microgravity Fluids Conference in Cleveland, Ohio, June 21-23. 1994.

il-423
Study qf Forced Convection Nucleate Boiling in Microgravity

PRINCIPALINVESTIGATOR:Prof. Herman Merte, Jr. University of Michigan

Co-INVESTIGATORS:

Prof. R.B. Keller University of Michigan

TaSK OBJECTIVE;

This task is a continuation of previous experimental work examining the effects of buoyancy on forced convection

nucleate boiling. In nucleate pool boiling, bubble detachment in normal Earth gravity is usually the result of

buoyant lorces; in the absence of buoyancy the bubbles have a tendency to remain in the vicinity of the heating

surface, eventually causing dryout at the heating surface which results in reduced heat transfer. For boiling in a

flowing liquid, an additional mechanism of bubble detachment can occur: detachment due to lift and drag on the

bubble, induced by the flow field. Understanding when this mechanism will dominate, and the effectiveness of

boiling in such circumstances, is important in making accurate predictions of microgravity boiling behavior. This

information will "also increase the understanding of boiling in cases where gravity is present.

TASK DESCRIPTION:

A closed-loop flow boiling system, using R-113 as the test fluid, has been developed as part of a previous program.

The temperature and pressure of the subcooled liquid R-113 are rigorously controlled at the entry to the test section.

A portion of one wall of the rectangular test section is electrically heated to provide either a constant temperature or

a constant heat flux. Surface temperature and heat flux measurements are made and the bubble growth/departure

process is recorded visually. The relative effects of buoyancy are examined by rotating the entire flow loop. Other

variables in the experiment are the flow velocity, the power input to the heater, and the amount of liquid

subcooling. A long-range goal of the effort is to adapt the current test loop lbr testing aboard NASA's low gravity

research aircraft.

The project has focused upon two general areas of study: obtaining heat transfer coefficients tot nucleate boiling

over a range of variables, and studying the conditions where dryout (departure from nucleate boiling) occurs.

Analysis has been performed in both areas of study to develop physical explanations for the observed results.

TASK SIGNIFICANCE;

An understanding of the fundamentals of boiling in microgravity is necessary in order to predict the performance and

limitations of space systems where boiling occurs, such as those for thermal control and power generation. Near

absence of natural convection in microgravity also provides researchers the opportunity to study fun "damental aspects

of boiling which can improve pertormance of terrestrial power generation and process equipment.

PROGRESSDURING FY 1994:

A study of the effects of orientation on tbrced convection flow boiling has been completed. Forced

convection-dominated and buoyancy-dominated conditions were observed and a parameter, the two-phase Richardson

number, ratio of the buoyant force to inertia forces in single phase flow was identified as the relevant indicator of

the dominant regime.

Modifications to the test facility, to extend the range of test conditions that can be achieved, are proceeding:

1. A new pump and flow meter has been installed, which doubles the liquid flow rate in the loop. It is digitally

controlled.

2. The temperature and pressure control systems has been changed from analog to digital control; the new system is

more precise and easier to operate, and will be better-suited for an aircrati experiment.

11-424
3. A new cooling system, to replace the existing tap water system, has been designed and will be built. Besides

being suitable for aircraft operation, the new system will also increase the range of subcoolings that can be

achieved.

A new experimental effort is underway to examine the effect of heater length-to-width ratio on boiling heat transfer

rates and on the departure from nucleate boiling.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 11/91 EXPIRATION: 2/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-05-68

MS Students: 1 MS Degrees: 2 RESPONSIBLE CENTER: LeRC

PhD Students: 0 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Brusstar, M.J. and Merte. H. Jr. "The effect,s of buoyancy on the critical heat flux in forced convection". AIAA J. of

Thermophysics and Heat Transfer, 8,2. 322-328 (April-June 1994).

Kirk. K.M. and Merte, H. Jr. Low velocity subcooled nucleate flow boiling at various orientations. Accepted fl_r

publication in ASME J. of Heat Trans. i 1994).

NASA Tech Briefs

Merte, H. Jr. "A study of forced convection nucleate boiling in microgravity", Technical presentation at Microgravity

Fhfids Physics PI Meeting at NASA Lewis Research Center, Cleveland, Ohio. NASA Tech Brief, (June 15. 1993L

Merte. H. Jr. "Pool and flow boiling in variable gravity and microgravity', Technical presentation at NASA sponsored

Second Microgravity Fluid Physics Conference, Cleveland. Ohio. NASA Tech Brief. (June 21 - 23, 1994).

Presentations

Kirk. K.M. and Merte. H. Jr. "A mixed natural/forced convection nucleate boiling heat transfer criterea." Heat Transfer

1994, w_l 7, 478-484. Proceedings of the 10th International Heat Transfer Conference. Brighton, England. August 14-18,

1994.

Li, L. and Merte. H. Jr. ""Bubble dynamics and forced convection boiling heat transfer with low velocity"." Report NASA

Grant 2-1310. Report No. UM-MEAM-93-09. The University of Michigan, Department of Mechanical Engineering and

Applied Mechanics, October. 1993.

ii i i i I i I ii I I Ii i i i i I I i i i i I I Iu i i i i i i Ili I i ii i i i i i i i i i i i I i i, i i i t i i i i i i I i ii i I i i i i i i i i ii I ii i i 1 ! i I I i iI ii I i I i ii i i ii ii i i, lii I ii I ii i ii i I I i i i i i ii I ii Iii I I ii I iii i ii Iii ii i i is i i ili ili Ii i I i i i i I i i i l I Ii i ii i i i ii i i i i i,, I ii i i i ii i i i t i i iI i i i I ii i I I I, iI i i i i i i i i i i i, i ii

11-425
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

_tI_|_|_|_u_II_ui_i_|iu_0_H_I_u_I_I_H_D_u_ j_I|_|_ii_I_uI_in_i_H_i_H_i|_I_u_u_H_g_!_!_11_|_l_I|t IlUlnllllllHI011011.1.1n_lllllllltlllllll.l|lll|ll01111nllH

Control of Oscillatory Thermocapillary Convection in Microgravity

PRINCIPAL INVESTIGATOR:Prof. G. P. Neilzel Georgia Institute of Technology

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective is to experimentally investigate active control of oscillatory thermocapillary convection in planar

layers. The investigative strategy is as follows:

1. Establish the appropriate basic state for a "thin" rectangular flow geometry described in the subject proposal.

2. Establish and detect the oscillatory thermocapillary convection in the form of hydrothermal waves.

3. Suppression and control of the hydrothermal waves.

TASK DESCRIPTION:

The basic state will be investigated using available computer programs to help establish the experimental design

parameters and boundary conditions. After choosing the relevant design parameters and boundary conditions, the

dish which will contain the desired basic state will be constructed. The desired basic state is the return flow basic

state of Smith and Davis. LDV will be used to observe and measure the basic state obtained in the experiment.

The surface temperature perturbations of the hydrothermal waves will then be characterized either numerically or

experimentally. Control or suppression of the hydrothermal waves will be attempted using a CO, laser as the heat

source. Locations along the free surface that appear to most effectively cancel or suppress the hydrothermal waves

will be heated with a laser pulse and the duration and time of pulsing will also be compared with the predicted

estimates.

TASK SIGNIFICANCE:

Crystals grown by the float-zone process can be improved by successfully supressing undesireable fluid motion

during the crystal growth process.

PROGRESSDURING FY 1994:

Recent progress has been made using the apparatus modified following the preliminary experiments. For some

layer depths, an instability of the planar basic state in the form of a steady, multicellular structure was detected. It

was subsequently learned that when driven to higher Marangoni numbers these states became oscillatory. This was

originally detected through the use of flow visualization with both sheet-illuminated particle photographs and a

newly implemented shadowgraphic technique. The shadowgraphs appear to be more sensitive than the particle video

in detecting the onset of oscillations.

By varying the depth of the layer, we changed one of the principal control parameters, the dynamic Bond number.

Additional experiments yielded the exciting result that, for small layer depths (small Bond number), a direct

transition from steady, unicellular motion to oscillatory motion was observed. This is the transition expected on

the basis of the Smith & Davis (S&D) theory which motivated this project; since the S&D theory assumed zero

body Ibrce, corresponding to zero Bond number, it was anticipated that we had, indeed, detected hydrothermal waves.

This was pursued with increased vigor following the acquisition of our intiared (TR) camera system, which 'allowed

visualization of the free-surface temperature. The steady, multicellular state shows a pattern of transverse rolls, i.e.,

rolls with their axes aligned normal to the free-surface velocity. When this mode became time-dependent, the

_6_I_Do_4_l_I_I_I_j_o_g_t_j_I_D_*_*_*_j_*_j_I_*_I__f_I__

11-426
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

n_!i_ii_i|_i_ini_|_s_|iI|_i|i_iin|iie|in_i_n_II_II_"_i_nii_i_ioiii_iiI_i_u_i_iiiii_i_n_in_iii|i_H_iIii_iiii_|i_i_!_ii_j_i_io_i_iHii|iiii_ii_iit_In_inH_H_H_i_iiii!_iiii_i_ii_i_!_i_illi|niH_ni_

oscillations progressed ti'om the cold wall as a pair of oblique waves superposed on the transverse rolls. This would

be a difficult mode to attempt to suppress. For the low-Bond-number transition, however, a single set of oblique

waves was observed moving from the cold wall to the hot one. This again, is in line with the expectations from

the theory of S&D and the subsequent nonlinear analysis by Smith. It is also the structure hoped for from the

standpoint of control.

We are presently extracting free-surface temperatures from the IR camera data. This will allow the determination of

the tree-surface temperature gradient in the core of the layer, away ti'om the boundary, layers at the heated-cooled

walls. This, in turn, will allow the computation of a Marangoni number which is device independent and in

agreement with theoretical practice. When this is accomplished, it is hoped that the expermaental results, for the

low-Bond-number transition sequence, will be in much closer agreement with theory.

We shall begin shortly with implementing the proposed control strategy. Given what we have learned about the

influence of buoyancy, we will focus on the oscillatory states which exist at low Bond number. We will most

likely restrict the bulk of our efforts to studying the 1 cS silicone oil with which we have had the greatest success.

While we would like to investigate a 0.65 cS oil, to allow investigation of the effects of Prandtl number, we have

had evaporation problems which render the data suspect.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 2/93 EXPIRATION: 2/96

PROJECT IDENTIFICATION: 962-24-05-61

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONSFOR FY 1994:

Presentations

Riley, R.J. and Neitzel, G.P. "Hydrothermal-wave and steady, multicellular instability of a thermocapillary-buoyancy

driven flow." Presented at the 47th Annual Meeting of the Division of Fluid Dynamics of the American Physical Society.

Atlanta, GA, November 20-22, 1994.

i I I I I Il II I I I I I i l I I I * I I l I Il I i I l I l I I l l III III I i i i i I ii I I l I I ii I l I i ll I l I I I Iil i le II l |11 III III lI l I I l I I l l III lI Ill el III II III II I I II l Ill I l l l I I l I I lI I Ili I l I I I I I I I iI I II l i I l I I l I Il Ii I I i i I I I I il eI I I II i I I _l I I I I i i i II iI iii I I iii i i eI I iI lii i i I I I I I ii i ii i i i i i I i i i i i ii i i i I

11--427
|I. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

lllillllllelll|ll|! J|llll!o|llnllllllll6nllllg|lQIIllllnln;olnlllllllllllnll|llll!ll!lla JIIsl||ll!loll|t tnllnllllnlolllllolllll_llllllllll!t glnlellg|il!!gllllnllll_lll!lall|lillllellllltl!ll|lllll|ll!l|llllollel! 01|l|H||||l!|ll0il*ll|DI0|lllil

Industrial Processes

PRINCIPALINVESTIGATOR: Prof. Simon Ostrach Case Western Reserve University

CO-INVESTIGATORS:

Prof. Y. Kamotani Case Western Reserve University

TASK OBJECTIVE:

The objectives of this study are to gain an understanding of the role of gravity in various industrial processes and to

develop new applications of microgravity.

TASK DESCRIPTION:

The commercial processes and related basic processes which have been investigated or are being investigated, include

supercritical extraction processes, coating flows, formation of bubbles in liquid flow, dynamics of liquid-gas

interlaces, transport phenomena in zeolite growth, rotating electrochemical systems, and transport phenomena in

crystal growth. The roles of gravity in those processes are being studied by using experimental, numerical, and

analytical techniques and potential benefits of microgravity are being assessed. Based on those studies microgravity

experiments will be proposed.

TASK SIGNIFICANCE:

The roles of gravity in terrestrial and space-based industrial processes are being studied by using experimental,

numerical, and analytical techniques, and the potential benefits of microgravity applications of these processes are

being assessed. Based on these studies, microgravity experiments will be proposed which will lead to an

understanding of how to best utilize the environment of space/'or various industrial applications.

PROGRESSDURING FY 1994:

1. Coating Flows

An experiment on dip coating is being conducted to study the conditions Ibr the appearance of wavy films. The

experiment covers the capillary number up to 20 and Reynolds number up to 28. When the non-dimensional film

thickness exceeds a certain critical value, the film interface becomes wavy. The nature of the interlhcial instability

is investigated by flow visualization. According to the present experiment a coating film becomes unstable after

certain Reynolds number and Stokes number are exceeded. The applicator geometry also influences the film profile

and thickness. One conclusion from the present experiment is that gravity significantly influences the stability of

the coating film and thus coating in microgravity is advantageous in obtaining unitorm films.

2. Bubble Generation in Microgravity

The main idea in this work is to study single bubble generation with transition from the bubbly to the slug flow

regime in a continuous liquid flow under microgravity. We are using the Fluid Flow Diagnostics Loop Facility at

NASA/Lewis to run experiments under normal gravity conditions. Both co-flow and counter-flow systems have

been designed and are now in the manufacturing process. The 1.27 cm I.D. flow conduit section is assembled and

certain modification are made in the data acquisition system. After some testings with the 1.27 cm flow conduit

system, pipe diameters and injection nozzle diameters will be varied to observe the changes in flow regime

transition.

3. Zeolite Growth

We have found a way to grow large zeolite crystals. By adding nutrients during the growth period it is possible to

put the extra nutrients into the existing crystals without increasing the number of crystals, thereby increasing their

11-428
average size. A patent has been applied lbr the method. The time to add the nutrients is determined by observing

the shrinkage of the gel mixture. The method is considered to be very, effective in growing large crystals in

microgravity. However, in microgravity the gel does not shrink, but it becomes dilute gradually as the crystal

growth proceeds. We found that by putting a He-Ne laser through the get it is possible to know structural changes

in the gel, which makes it possible to identify the time to add the nutrients. We are also studying theoretically the

diffusion processes taking place during zeolite growth in microgravity.

4. Rotating Electrochemical Systems

The mass transfer process in shallow rotating electrochemical cells is being investigated numericallyI analytically,

and experimentally. Various cases relevant to rotating battery, applications (Schmidt number about 3,000) have

been computed numerically. When the rotational speed exceeds a certain value, secondary cells appear in the core

region. We are also performing a scaling analysis to identify new dimensionless parameters and a mass transfer

correlation which can classify the entire range of our interest. Based on the numerical analysis we are constructing a

new electrochemical test cell. Sectioned electrodes which are specially designed to measure the local mass transfer

rate have been fabricated.

5. Natural Convection in Circular Cylinders

Oscillatory. natural convection in circular cylinders lilled with a liquid metal is being investigated expertmentally.

The conditions for the onset of oscillations are being investigated under various conditions. The problem is very

complex and many factors influence the oscillation phenomenon (e.g. heating rate, wall thickness).

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: O

MS StudenL_: 0 MS Degrees: 3

PhD Students: 4 PhD Degrees: 3

TASK INITIATION: 1/89 EXPIRATION: 3/96

PROJECT IDENTIFICATION: 962-24-05-30

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Kamotani. Y.. Weng, F-B, Ostrach, S. and Platt, J.

Jtmrnal of Heat Transfer. Vol.l16, (1994L

Oscillatory natural convection of a liquid metal in circular cylinders.

Kim. 1.. Kamotani. Y. and Ostrach. S. Modeling bubble and drop formation in flowing liquids in microgravity. AIChE

Journal, Vol.40.No.1. (1994).

Zhang, H.. Kamotani, Y. and Ostrach. S. Modeling of the zeolite crystal growth process in microgravity and comparison

with spaceflight results. AIAA Paper 94-1796.

Presentations

Zhang, H. Kamotani, Y. and Ostrach. S. "Modeling of the zeolite crystal growth process in microgravity and comparison

with spaceflight results." 1994 AIAA Aerospace Sciences Meeting. Reno. NV, January 1994.

11--429
Marangoni Effects on the Bubble Dynamics in a Pressure Driven Flow

PRINCIPALINVESTIGATOR:Prof. Chang-Won Park University of Florida

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

Perform theoretical and experimental research to investigate the effect of surface contamination on the relative

motion of air bubbles in a liquid within a Hele-Shaw (HS) cell. Results of this effort will be used to enhance the

understanding of the fundamental physical processes and the importance of interracial flows that occur in a broad

variety of industrial and process of applications.

TASK DESCRIPTION:

• Focus the theoretical investigation on establishing a predictive model for the influence of surfactant on the bubble

dynamics (especially on the translational bubble velocity in a pressure driven flow).

• Experimentally contirm the theoretical predictions and prove that many of the perplexing bubble shapes are the

results of the surfactant influence.

TASK SIGNIFICANCE:

The results of this research will provide an understanding of the bubble motion on diffusional flux of heat and mass

at the bubble-liquid interfaces. This has a close relationship to a number of applications in direct contact mass and

heat transfer devices, bioengineering (e.g., blood oxygenation), and it has direct implication for the fluid systems in

space-based applications.

PROGRESSDURING FY1994:

This project was initiated on June 29, 1994. The main objective of this research is to investigate the

suffactant-induced Marangoni effects on the motion of bubble/drops in a confined geometry. A Hele-Shaw cell,

which is a thin gap between two closely space flat plates, is used as a model system for this study. Preliminary

experiments have been conducted to date on the motion of an air bubble and a water drop through a silicone oil. An

order of magnitude difference in mobility has been observed between the air bubble and a water drop. This difference

is presumably due to the influence of surfactant present in the system as contaminants. A systematic experiment is

planned to delineate the surfactant influence.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-92

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Park, C-W, Maruvada. S.R.K.. and Yoon, D-Y. The influence of surfactant on the bubble motion in Hele-Shaw cells.

Phys. Fluids, Vol. 6, no. 10, 3267-3275 (1994).

|_|_!||_I||_e_|||_!!_s_!_e_o_|_!_|_!s_I_||I|_e_s_||!|_e_!_!_|_!_|!_!_|_|s_|!|!_|!!_!!_!_e_|t_|!!!|!!!!_||_|_!|!!|!!_!!e|_||_!|_!!e!_!|_!_e_|_!!!_|_!|!||_|_|_!I_o!e!_e!_!_|_e_e_I_I|_I|II|t_

11--430
Two-Phase Interfaces in Weak External Fields.

PRINCIPALINVESTIGATOR: Prof. Jerome K. Percus New York University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

This endeavor expects to establish a theoretical framework that describes the interracial response of fluids that have

attractive and repulsive contributions, in interparticle interactions, to external fields -- particularly a gravitational

field. The most interesting result will be the elucidation of how gravitational forces at the microscopic level play a

key role in interface dynamics.

TASK DESCRIPTION:

1. Analytical Statistical Mechanical formalisms will be employed. Classical Hamiltonians of the interlaces of

interacting fluids will be m_lified or developed as needed.

2. Gravitational external fields are included, but the formalism will be more general;.

3. Equilibrium followed by non-equilibrium descriptions are to be developed. It is expected customary as well as

new analytical strategies will be utilized.

TASK SIGNIFICANCE:

The basic fundamentals of this project is to explore the statistical mechanical basis of three-dimensional

liquid-vapor interface formation when an external field of arbitrary magnitude (such as low gravity) is applied. Such

fundamental work is expected to point to new experimental observables which have not been anticipated to date.

Much of the statistical mechanical interface work in the past has been limited by avai "lable tractable methods and ad

hoc postulation of interlace existence. Only when observed phenomena such as ,interthce existence and shape are

natural outcomes of first principles formalism, can one expect to predict new phenomena from the same lormalism

that increa_ses our understanding. An example from this work is the prediction of a new phase transition that (x:curs

between the uniform vapor state and one with small droplets.

PROGRESSDURINGFY 1994:

The following describes three important phases of this project:

1. The existence and shape of an equilibrium liquid-vapor interface has been derived from a formalism where the

short range repulsive part and long range attractive part of the intermolecular potential have been treated with

separate limits (hydrostatic and mean field, respectively) in the ensemble averages. This work naturally predicts

existence and shape, plus a likely observable phase transition not previously known. This work has been accepted

for publication in the Journal of Statistical Physics.

2. A second part of the work done in FY94 has dealt with the decomposition of equilibrium states into

coarse-grained virtual configurations. It is expected that this will aid in the understanding of the evolution of shapes

in arrays of bubbles and droplets, and in foams. A report has been submitted to the Journal of Statistical Physics.

3. The third part of this project moves to nonequilibrium dynamics. Nonequilibrium Monte Carlo techniques are

being used to predict cluster growth rates and test analytical models. Also, interfacial motion is being studied by

the use of multiple time scale separation growing out of the multi-configuration decomposition referred to earlier.

The latter work will be a focus lbr FY95.

It_t_*_*_i_I_I_t_**_I_*_I_B_*_*_O_I_o_I_*_*_*_*_*_*_*_*I_*_*_*_*_*_*_*_II_*_*_*_*_*_*_*_*_*_**_*_

11--431
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-05-76

NASA CONTRACT NO.:NAG3-1414

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Keissling, M.K.-M. and Percus, J.K. Non-unification Vander Waals theory. Journal of Statistical Physics, (accepted).

i i I I I I I I i ii I i II i i g ! II I il il I Iii i ill i li iii i Jill I I ii I I I I II I I il ! I11 |11 II II I III ! II g I I I II! I i I I il I I I OII I i I I II ! I I OII i II ! I I ! I! I I Ii II I III I Ill Ill Ig I II llil I II I I II I Illl II Ill! Ill I It I II I II I I! I I l ! Iill ! I I I II I I I I I i! I II I I I I I I I I gi I Ii I II li IIII IIII II I II 0ill I il II l II II I

11--432
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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ContainerIess Capillary Wave Turbulence

PRINCIPALINVESTIGATOR: Dr. Seth J. Putterman University of Califomia, Los Angeles

CO-INVESTIGATORS:

M.B. Barmatz Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

We are working toward the goal of studying turbulence in a broad-band spectrum of capillary waves that run around

the surface of a containerlessly positioned drop of liquid. This experiment would constitute the first controlled

measurement of turbulence in interacting waves.

TASK DESCRIPTION:

The problem consists of two components. They are (a) the generation of a turbulent distribution of surface ripples

and (b) the detection and measurement of this state. These issues are being approached in ground-based experiments

as well as in arrangements that stmulate containerless fluids in microgravity. The ground-based experiments are

being carried out in a fluid which is excited with a shake table. The preflight experiments are being developed with

a levitated droplet of liquid.

TASK SIGNIFICANCE:

Consequences of this experiment range from the characterization of turbulence to the determination of universal

properties of nonlinear systems and signal processing. The presence of a new propagating mode (second sound) in

the capillary turbulence would have important ramifications with regard to attempts to achieve controlled

thermonuclear fusion.

PROGRESSDURING FY 1994:

We have achieved the first controlled observations of the transition to broad turbulence in nonlinear wave

interactions. These experiments studied the motion of ripples propagating on the surface of water. The key to these

measurements is our ability to determine the height of the rippled off-equilibrium fluid as a function of location and

time. The fluid is set in motion with a vibration exciter ("shake table"). A CCD camera mounted above the liquid

and focused on the surface records the intensity of light that leaves the surface. By doping the water with

"polyballs" (neutrally buoyant spheres with 1 micrometer radius) the light is forced to diffuse through the water, so

that the intensity at the top surface is proportional to its local elevation. This new technique (diffusive light

imaging) is our key advance. It circumvents the catastrophic problems posed by caustics in the former shadowgraph

imaging technique.

Our technique can be used to measure the power spectrum or the instantaneous surface topography. Thus the first

records of the full 3D profile of a localized soliton state has been obtained. Our data shows a power spectrum of

surface vibration given approximately by _2(03) _ 6o.4.6 where _(x,y,t) is the surface height and "03" is the

frequency. This compares with a theoretical dependence of co_/6"

Whether we have found a mistake in the theory or if the effects of boundaries (e.g. the side walls of the dish) and a

limited dynamic range has led to this discrepancy will be best answered by a flight experiment!

In a space flight the ripples will be excited on the surface of a levitated drop. For this reason the JPL group has

been studying the dynamics of large amplitude ripples on a levitated drop of fluid. Excitation of large amplitude

waves has been achieved with a "sting" and through modulations of the ultrasonic levitating field. Dipslacement

spectra of the surface oscillations of levitated drops have been obtained using a modified Polytec PI interferometnc

laser vibrometer with a front-end anti-slosh optics developed by NASA Lewis (Meyer/Tin/Taylor/Mann) for

I1--433
UCLA/JPL (Putterman,q3armatz/Biswas). This front end optics design was "also applied to measure displacement

power spectrum on a fiat liquid surface with amplitudes as high as seven hundred microns (well into the turbulence

regime). This new instrument is under development at NASA Lewis (funded by Code UG) and will be assigned to

JPL to assist in characterizing surface capillary wave phenomena on a levitated drop.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 12/91 EXPIRATION: 12/94

PROJECT IDENTIFICATION: 963-24-07-03

RESPONSIBLECENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Greenfield, A., S. Putterman, W. Wright. Observation

Physics Letters, (To be published).

of a localized chaotic structure in a non-linear oscillatory lattice.
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

;ill I IJlJ|l a|l|l III i i i|_l_ I I! i iii aI Ill! i i l i I| I a i! i i tllJl I I I I i i 1111111 i! i H I H Im|l I HI. I U II I I I J III mIJill _ I! I a J l _ l a I I IS I H I I 0|tie I I I 11 J l I|e II lU HHe I I tl I |1 M|U |H I_l ||JUH|_I01 I It In||llllalelle J_lel_enl_lllNitu_|_e_lell_len_l|ll|ll

Studies of Radiation-Driven and Buoyancy-Driven Fluid Flows and Transport

PRINCIPALINVESTIGATOR:Prof. Paul D. Ronney University of Southern California

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The proposed research will consist of two sets of experiments under simulated microgravity condition. The first is

a study of instabilities of radiating, initially-homogeneous gas volumes, for both optically-thin and optically-thick

gases with vertical temperature gradient between two plates. The objectives are to determine the validity of

theoretical stability criteria and to determine the spectrum of the nonlinear evolution of the resulting densifications.

The second set of experiments is a study of the stability of one-dimensional steady temperature profiles and unsteady

thermal conduction waves in gases with strongly temperature-dependent radiative conductivity. The objective is to

determine the stability criterion, study nonlinear evolution's of these instabilities, and develop a stability model.

TASK DESCRIPTION;

The following are proposed problem studies:

1. Stability of a cooling optically-thin gas volume (field instability) using NH3 gas condensible L_vapor or other

gas with analogous properties, and measurement of the power spectrum of any resulting nonuniformities.

2. Stability of a cooling optically-thick gas volume which is opaque only at high temperatures (CMBR instability)

using CO or other gas with analogous properties, and mea.surement of the power spectrum of any resulting

nonuniformities).

3. Radiative conduction in optic_dly-thick gases between parallel plates using SF6.

a. Radiatively-induced instabilities of steady planar conduction profiles at lag.

b. Unsteady planar conduction at constant heat flux (thermal waves) at one-g and lag.

c. Critical Rayleigh numbers at one-g at large t and AT.

4. Radiative conduction in opucally-thick gases at lag in spherical geometry.

5. Theoretical stability corresponding to items 3 and 4

TASK SIGNIFICANCE;

The study of the coupling of internal radiation to fluid flow is important in a wide variety of practical problems

including glass and semiconductor processing; oceanographic, atmospheric and astrophysical flows; plasma physics;

combustion systems; solar energy collection; and heat transfer in inhabited enclosures. This work consists of a

series of experiments to be canned out in the drop towers that will enhance the understanding of the physics of

internal radiation to fluid flow. Results obtmned from the present research could identify potential mechanisms to

improve the Earth's environment and improve solar power systems.

PROGRESSDURING FY 1994:

We have presently constructed an apparatus consisting of two parallel flat plates, each 12 cm x 12 cm, with a gap

between the two varying from 2 cm to 5 cm. The upper plate will be heated to an adjustable temperature using an

electrical heater imbedded in the surface facing away from the lower plate. The lower plate will be maintained at a

constant temperature (approximately 300 K) by ten thermoelectric cooling devices embedded in the plate in a manner

similar to that of the upper plate. The plates have been constructed of aluminum so that their thermal response

II--435
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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time will be very large compared to the low-gravity test duration. A well insulated, sealed aluminum chamber to

contain the plates and the radiating gas.

We have constructed a shearing inferometer system for flow visualization, since the fluid flow will not be visible to

the human eye. This particular interterometer is advantageous because we can extract both qualitative and

quantitative information from the images produced and because it is more robust than other interferometer systems.

To record the visual images, a camera will Oemounted to the structure. It will be linked 03 a recording device on

the drop platform by a sufficiently long fiberoptic cable, provided by the drop tower facility.

STUDENTS FUNDED UNDER RESEARCH: TASK iNITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION'. 962-24-05-93

MS Students: 1 RESPONSIBLECENTER: LeRC

PhD Students: 0

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11436
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

Fluid Creep Effects on Near-Wail Solute Transport for Non-Isothermal Ampoules and Suspended

Particle Transport Coefficients

PRINCIPALINVESTIGATOR:Prof. Daniel E. Rosner Yale University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

This experiment tocuses on the tormulation of fluid creep (slip)/solid boundary conditions over a broad range of

fluid densities. This proposal seeks to initiate the theoretical studies necessary to provide the basis for more

realistic ampoule-level numerical simulations lor vapor transport, including supercritical vapors, and to provide

predictions of particle transport properties based on similar phenomena occurring at the particle level.

TASK DESCRIPTION;

The following are issues to be addressed in this investigation:

1. Slip coefficients for polyatomic gases, including nondilute, disparate molecular weight mixtures.

2. Simultaneous effects of solid wall creep due to solute mass-transfer, including the coupling between creep

associated with energy and mass transfer.

3. Nature of the transition to that of liquid-like densities.

4. Appropriate "creep" conditions at "'porous" solid surfaces and implications for the transport properties of

suspended pamcles.

TASK SIGNIFICANCE:

Knowledge of these phenomea will "allow a greater understanding of the crystal growth process which affects a

number of industries (including pharmaceutical/medical).

PROGRESSDURING FY 1994:

This grant was funded on July 17, 1994. The appropriate personnel are being brought on board and equipment is

being purchased.

STUDENTSFUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 2

TASK INITIATION: 6/94 EXPIRATION: 5/96

PROJECT IDENTIFICATION: 962-24-05-94

RESPONSIBLECENTER: LeRC

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11--437
It. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

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Dynamics of Superfluid Helium in Low Gravity

PRINCIPALINVESTIGATOR:Dr. Graham Ross Lockheed Missiles & Space Co.

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this project is to simultaneously record the 3-axis acceleration time history and make a video

recording of the position of superfluid helium (SFHe) in a test cell while in a low-gravity environment. This data

can then be used as a benchmark tbr validation of a 3-D CFD simulation of SFHe flow behavior.

TASK DESCRIPTION:

The First part or" the project is to build a SFHe dewar and a support equipment package to allow operation of the

dewar and recording of 3-axis accelerations and video images of the fluid motion on the KC-135. The dewar will

have optical windows in the side to allow viewing of the liquid helium in the inner test cell. The data recording is

intended to be digital data stored on a hard disk. The float package will be self-contained except for power and

supply of liquid helium.

The completed dewar float package will be taken on the KC-135 for one or more flights to observe the motion of

the liquid in low gravity. The recorded accelerations will be used as an input to a LMSC-developed CFD code that

incorporates the two-fluid model of SFHe. The simulation output will be compared to the actual fluid motion

recorded during the KC-135 flight to verify the accuracy of the computer mode,

TASK SIGNIFICANCE:

The final product of the project will be to have a CFD code for SFHe that has been verified in low gravity. This

will allow predictions of SFHe behavior on future satellites such as SIRTF, GP-B, and AXAF with increased

confidence in the accuracy of the simulation.

PROGRESSDURING FY 1994:

The objective of this contract is to perform low gravity verification tests of a computational fluid dynamics (CFD)

program that incorporates the two fluid model of superfluid helium (SFHe).

Accomplishments

The original proposal included the fabrication of a complete new SFI-{e dewar and float package to perform the

verification experiments. This task has been simplified due to the availability of an existing SFHe dewar and float

package through JPL. The program plan has been modified as a result of discussions with Peter Mason and Bob

Chave at JPL to reuse the dewar and some of the existing support equipment while procuring new hardware to

improve the robustness and data-taking capabilities of the system. JPL is upgrading this equipment to have it

available as a NASA resource for researchers using SFHe with some refurbishment work being done under this

contract. The net result is that it should be possible to conduct the first low-gravity experiments a year earlier than

originally proposed.

The technology development related to the use of Lexan as the structural material for the SFHe dewar is proceeding

with the obiective of providing a replacement unit for the inner SFHe test cell for the existing dewar. A bonded

joint between the stainless steel vent lines and the Lexan body has been designed and tested with no leaks after

thermally cycling the joint to liquid nitrogen temperatures. The SFHe test cell has been designed and is being

fabricated. It will be thermally cycled, proof pressure tested, leak tested, and tested with SFHe as a separate unit; it

will then be incorporated into the JPL dewar for laboratory tests and possible use in later low-gravity experiments.

i i I Ol i oo nol I OI oOil oooI I l I IooooOOlOOll Ol OOlOOI O|O OOlO O II OOl I I OIO nI I OI I II I I I OI OIOOOOOOOI i I OI OI IOI Ion i I I I OI I IO OI II O OI OI i oi i OI O I OOil Ii l I Oi onO IOOI OOOtll I Ol I O I OI I Ol i Oi OOi onoi I I I I OI I i i OUlo I Il I I uOOOOI l I OIO IaoI IO OOOOO I O I OI I IO I aI O I I I |Ol OOI IOl Itl II

11-438
Achangehas',also been made in the computer resources to be used to run the CFD code for this project. This change

w&_ induced by accounting changes at Lockheed that now have computer usage costs charged directly to the contract

rather than treated as indirect costs. JPL will be making their Cray computer available at no cost to this project.

There will be licensing charges from the software vendor for use of the ba._e code on a new machine, but this is

anticipated to be relatively low compared to the contract cost of running the code on the Lockheed Cray.

Plans

The refurbishment and upgrade of the JPL dewar and float package is planned to be completed by the end of

December with the hope of performing the first low-gravity experiments on the DC-9 out of the NASA Lewis

Re'search Center in February.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/93 EXPIRATION: 10/96

PROJECT IDENTIFICATION: 962-24-07-18

RESPONSIBLECENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Ross. G.O. "Helium LIslosh in low gravity." Proceedings of the 2nd Microgavity Dynamics Conference.

Ross, G.O. "Behavior of superfluid helium in low gravity." Proceedings of the NASA/JPL1994 Microgravity Low

Temperature Physics Workshop.
MicroscaleModelingof Microgravity Multiphase Flow

PRINCIPALINVESTIGATOR:Dr. Paul H. Rothe Creare, Inc.

CO-INVESTIGATORS:

Dr. G.B. Wallis Dartmouth College

TASK OBJECTIVE:

The general objective is to investigate the feasibility of modeling adiabatic multiphase flows on Earth in facilities

of very small scale. The specific objective of this contracted effort are to build, instrument, and test a small

muitiphase flow loop on the order of I mm in diameter. This loop -- designed and operated for appropriate flow

conditions and geometries -- will potentially scale larger space-based multiphase flow systems.

TASK DESCRIPTION:

The principal investigator (PI) will identify, via the appropriate scaling argument, the important non-dimensional

quantities governing multiphase flows. The PI will demonstrate, by dynamic similitude, how closely on-orbit

conditions can be simulated with this tiny system. A system that is appropriately sized for the proper range of flow

conditions will then be designed and built. A comparison will be made between data from this loop and the

following: representative data already available from ground tests and low-gravity aircraft tests at larger sizes,

existing theory, and in-house numerical models. The relevant data pertain to flow regime and pressure drop

predictions.

TASK SIGNIFICANCE:

A successful effort will demonstrate a method by which relatively expensive on-orbit, low-gravity, multiphase flow

experiments can be complimented, or even simulated, by low-cost, earth-based microscale expertments. Enhanced

knowledge will contribute to the design of multiphase thermal control systems being planned for satellite systems,

on-orbit space stations, and even moon/planetary applications.

PROGRESSDURING FY 1994:

The investigators have completed a feasibility study of using tiny "microscale" facilities on Ea_rth to model

multiphase flow in microgravity. Research work was completed early in FY94. The task final report was

completed and delivered in March, 1994.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 6/94

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-70

MS Students: 1 RESPONSIBLECENTER: LeRC

PhD Students: 0

BIBLIOGRAPHICCITATIONS FOR FY 1994:

NASA Conference Publications

Rothe, P.H., Martin, C., and Dawning, J. An application of miniscale experiment on Earth to refine microgravity analysis

of adiabatic multiphase flow in space. NASA Conference Publication, 3276, (June 1994L

i i i I I I i i I I II I I le I I i i I I i i I I i i i i I I I I I I I I I I I II II III I I I I i I i I I II I I i I I I I I I II I i I I I I I I I i i I II I I I I I I I I I I II I I I I I i I I II i i i i i I i i i i i I i II I II I I I I I I I I I i I I I I I I i"Ii I I I I l I I I I i i I I II i i i I i i i I I I I I I I !I l I I i i i i I I I Ii I i i i i i i i i i i i i i I I I I I i i i i i i i i i i i i i i i i! i| i i i i ii i i i i Ii I II I I I i i

11440
Gas Flow from Porous Media and Microgravity Battery Spills

PRINCIPALINVESTIGATOR: Dr. Robert T. Ruggeri Boeing Company

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

This proposal is based on the hypothesis that spacecraft battery failures can be traced to electrolyte spills resulting

from gas expanding inside the capillary pores of battery electrodes. The specific objectives of this project are as

follows:

1. To determine the gas capacity of three porous metals as a function of pore volume and pore diameter

2. To determine the system temperature and pressure effect on gas capacity.

3. To determine the effect due to the external geometry, of the porous material.

4. Analytically determine the effect of gravity on electrolyte spills.

TASK DESCRIPTION:

The objectives will be accomplished by one-g experiments and analysis. The PI will identify all critical parameters

that determine a porous metal's gas capacity, then demonstrate, by measurement, the effective volume of

noncondensable gas contained within the pore structure of porous metal plates as a function of the identified critical

parameters. Such critical parameters are expected to be pore diameter, pore volume, sample shape, temperature,

pressure and surface tension. The pore volume and the effective gas capacity of three metals well be determined in

volumetric gas flow experiments. The experiments well be conducted at 25 °, 45 °, and 60 °C in a constant

temperature chamber. Zinc, silver, and nickel are the three metals that well be investigated. The effect of pressure

cycles will span a range between 14.5 psia and 2.9 psia for each temperature. One to three pressure cycles will be

pertormed for each metal specimen at each temperature. Numerical models will be developed to study the gas

capacity as a function of the pore diameter, the temperature, and the ambient pressure. The effect of gravity on

these experiments well be determined analytically.

TASK SIGNIFICANCE:

Spacecraft batteries have been documented to discharge electrolyte, which causes a short circuit. Electrolyte

discharging mechanism is not yet fully understood. In order to prevent mission failures in the future, critical

parameters which determine a porous metal's ability to hold and discharge gas should be investigated. This will lead

to design of batteries that can retain electrolyte in the microgravity environment of space and thus prevent battery

failure in space missions.

PROGRESSDURING FY 1994:

During this reporting period, the folliwing have been accomplished:

1. The contract with Boeing Company was officially started on the first of October. A kick-offmeeting was held

at LeRC on November 8, 1994. Project tasks were reviewed and the approach was discussed.

2. The hardware for the ground-based 1-g experiment were acquired. Setup and checkout will take place in the next

few months.

I1.-441
STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/94 EXPIRATION: 10/96

PROJECT IDENTIFICATION: 962-24-05-95

RESPONSIBLECENTER: LeRC

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11-442
II. MSADProgram Tasks -- Ground-based Research Discipline: Fluid Physics

Ground Based Studies qf Thermocapillary Flows in Levitated Drop

PRINCIPALINVESTIGATOR:Prof. Satwindar S. Sadhal University of Southern California

CO-INVESTIGATORS:

E.H. Trinh Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

For the measurement of the thermophysical properties of undercooled liquids, the idea of spot-heating a test

sample in a levitated state is to be explored and applied to relevant materials. That is, a liquid drop levitated in an

acoustic field could be heated on a small fraction of its area by a laser beam. In addition, simple filament heating

will also carried out, since this can be achieved with considerable ease. The physical interference of the filament

with the fluid mechanics will of course have to be taken into consideration. By carrying out the measurements of

the thermocapillary effects of such heating it is possible to derive the thermal properties of the sample. However,

this can only be done with the development of a successful predictive model of the system. The effort will theretore

consist of both expertmental and analytical work.

1.1 Analytical Part

The purpose of the analytical part of the proposed program is to develop such a model over several phases. The

major thrust at present is in ground based studies with plans for a future space expertment. In the current studies

therefore, the expermaentation will involve significant interference of the acoustic field. Thus,/or most cases for

ground based studies, the drops will be deformed to a spheroidal shape. In addition, there is general asymmetry of

the flow field. While it is acknowledged that many of these complexities do not arise in low gravity, there is a great

deal that can be achieved by ground based studies provided the interference by the acoustic field is fully accounted lot

in the analysis. For model development in the direction of a zero-g space experiment, analysis will be carried out

lor liquid shells and compound drops.

Under the scope of the current investigation, the "analytical work will consist of several tasks that will encompass

the formulation of the differential equations pertaining to levitated srops, their analytical and numerical solutions

and the development of results.

1.2 Expermaental Part

The expertmental problem of interest in this proposal is the thermal response of a spot-heated levitated drop m a

convective gas flow of varying intensity. The ulttmate objective of the tasks proposed is to quantitatively

determine the transient and steady-state temperature distribution on the drop surface as a function of time, sample

physical properties, geometry, and of the input radiant energy. Because of the coupling of thermocapillary and

thermoacoustic phenomena, the interpretation of the resulting thermal state must be carried out in conjunction with

the theoretical analysis of the problem. The expertmental work will thus be divided into several sub-tasKs, each of

which must provide data that can be directly correlated with theoretical predictions. Although the final goal will be

to carry out an experiment in microgravity, this proposal will limit itself to ground-based investigations using

proven experimental techniques in order to correlate with and to verify the theoretical work, as well as to develop

experimental methods lot a potential future microgravity investigation.

TASK DESCRIPTION:

In the usual Earth-based environment, the convective contribution arises due to buoyancy as well as to the effects of

the levitation mechanism. In this particular case, the sample may be levitated in a gaseous environment by a high

intensity ultrasonic field, and the convective flow field external to the specimen is caused by acoustically-driven

streaming flows in addition to the normal buoyancy-driven circulation. The heat transfer problem of determining

the transient and steady-state temperature distribution at the surface of the sample will also require the solution of

the flow field inside the drop driven by thermocapillary effects (and perhaps also by acoustic radiation stresses)

because of the surface tension gradient introduced at the drop surface by the localized heating. Under other

II--443
It. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

i s | i o | iI | I | e I I I | I I Ill * | I I |J I | |1 o | I| | I I e II o H o I Io | i g In I o J I | I Ii o |i ! I I I DI i | I I |I I | III | I | | i I e! I t II I I I | II | | I o I_ a o I | o I I ! I I e I _ e ! II DJ a ! i I I | I o | I I I I I o |t Is I I o ! i i t I 16 ! I o ! II I i o I i i | i o I I ii | Ia IIi | _ i i i | | I oI i i |! o I | iII I I I i i e i i g i iii I! I ill I | iii iIi | i t i I i ! i I I J I; ii I n* i

circumstances, the sample may be levitated in a vacuum or gaseous environment by electrostatic forces which do

not generate detectable outer convective flows or droplet distortion. This approach requires, however, the permanent

non-uniform charging of the drop surface; the effects of which are still unknown, but might "also alter the

thermally-driven capillary, flows.

Under these conditions, the relevant non-dimensional parameters will thus include the Reynolds numbers of the

internal thennocapillary-driven flow, of the steady outer acoustic streaming flow, and perhaps of the high frequency

acoustic particle motion. The Bond number will be of relevance in order to distinguish between low gravity and

Earth-based conditions. The Nusselt, Grashof and Marangoni numbers will also play a primary role. Because we

shall be restricted to rather moderate temperature and to conditions far enough from the boiling point of the liquids

investigated, mass transfer processes will not be taken into consideration in this case.

TASK SIGNIFICANCE:

The proposed research will provide fundamental understanding of the Marangoni flows associated with localized

heating of drops and bubbles. For ground based studies where there is interference from the acoustic field, a sound

numerical model will provide significant new information about the behavior of these complex systems. The new

work on compound drops will play a fundamental role for a zero-g space experiment. Most importantly, the model

development along with the experimental studies will represent fundamental groundwork for the measurement of

thermophysical properties of undercooled liquids.

PROGRESSDURINGFY 1994:

1. Experimental Work.

1.1. Outer acoustic streaming flows characteristic of ultrasonic levitators in 1 G:

The ultrasonic streaming flows have been investigated using smoke particle visualization inside empty levitation

chambers as well as around levitated isothermal and spot-heated solid and liquid samples. These studies clearly

indicate that the convective flow environment around a spot-heated sample is dominated by the interaction between

acoustic streaming and natural convection. Different regimes can be identified and vary from laminar, low frequency

oscillatory, chaotic, and finally turbulent as the streaming Reynolds number increases. Some of the findings have

been summarized in a publication by Trinh and Robey (1994).

1.2. Spot heating of a levitated drop in the ultrasonic-electrostatic hybrid levitator:

A pulsed CO2 laser has been used to spot heat levitated charged drops with radii on the order of 4-5 mm in diameter.

Heating from one side has been observed to generate the steady rotation of an initially stationary spherical drop with

angular velocity vector in the vertical direction. The thermal distribution at the drop surface has been monitored

with an Infrared imaging camera with a 0.1 °C resolution. The elimination of rotation by imparting an opposed and

controlled acoustic torque is being implemented together with an apparatus allowing heating along the symmetry

axis in the vertical direction.

1.3. The visualization of internal flows with and without radiant heating:

Tracer particle scattering and particle image velocimetry (PIV) methods are being implemented to obtain quantitative

internal flow velocity for the axisymmetric and steady case. A background internal flow field for electrostaticaUy

levitated charged drops in the presence of a weak ultrasonic field has been measured, and a typical velocity is on the

order of 0.05 cm/sec.

2. Analytical Work:

2.1 Thermocapillary Rows in a Spot-Heated Oblate Spheroid

From the previous pure conduction calculations in the case of axisymmetric spot heating of an oblate spheroid, the

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11--444
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

therm_d driving t_)rce at the interface has been applied to the calculation of the flow field. This has led to an

elaborate expression lor the stream function and numerical calculations are being tamed out. Since these results are

limited to the steady state and a weak thermal driving force, further progress will require fully numerical schemes

which will be developed.

2.2 Outer Acoustic Streaming Around a Spheroid

Following an earlier analysis of Lee and Wang on the problem of streaming around a sphere, the generalization to

an oblate spheroid has been carried out. The principal result is the development of the tangential component of the

fluid velocity outside the boundary, layer. This has led to the complete solution of the Stokes flow field around the

inner boundary layer region. Numerical calculations have yet to be carried out.

2.3 Thermoacoustic Streaming from a Sphere with Pulsating Spot Heatmg

Following the singular perturbation scheme of Gopinath and Sadhal (1994), for small values of the streaming

Reynolds number, an extension to the case of pulsating spot heating has been developed. The frequency of

oscillation is in tune with the acoustic field. Physically, the situation is achievable by means of a laser beam

directed towards a spherical sample. The thermal energy deposited is divided between the solid sphere and the

surrounding gas medium on the basis of the respective thermal transport characteristics. With a pulsating heat

source resonating with the acoustic lrequency, the time averaged energy equation yields a nonzero convective

transport. Some analytical dilt]culties have prevented the completion of this work. These will be resolved within

the next few months.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 1/93 EXPIRATION: 12/95

PROJECT IDENTIFICATION: 962-24-07-19

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Trinh, E.H. and J.L. Robey. Experimental study of streaming flows associated with ultrasonic levitators. Phys of Fluids.

(To be published November 1994L

Trinh. E.H. and K Ohsaka. Measurement of density, sound velocity, surface tension, and viscosity of freely suspended

supercooled liquids. International Journal of Thermophysics. (accepted for publicationl.

Proceedings

Gopinath, A. and S.S. Sadhal. "Thermoacoustic streaming effects from a sphere subject to a time-periodic temperature

disturbance." Heat Transfer 1994,' Vol. 5, pages 279-284, Tenth International Heat Transfer Conference, Brighton, UK,

August 1994.

Books

"Heat Transfer in Microgravity Systems - 1993." Edited by: S.S. Sadhal and A. Hashemi American Society of Mechanical

Engineers, 29th National Heat Transfer Conference, Atlanta, Vol. HTD-235, August, 1993.

"Heat Transfer in Microgravity Systems II - 1994." Edited by: S.S. Sadhal and A. Gopinath American Society of

Mechanical Engineers, International Mechanical Engineering Congress and Exhibition, Chicago, IL. Vol, HTD-295,

November 1994.

Presentations

Trinh, E.H. and S.S. Sadhal. "Acoustic streaming and ultrasonic processing of low melting point materials." 1994 ASME

International Mechanical Engineering Congress and Exhibition, November 1994.

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11-445
It. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Effects of Gravity and Shear on the Dynamics and Stability of Particulate and Multiphase Flows

PRINCIPALINVESTIGATOR:Prof. Ashok S. Sangani Syracuse University

CO-INVESTIGATORS:

Donald L. Koch

Michel Louge

Cornell University

Cornell University

TASK OBJECTIVE:

To understand the particulate and multiphase flow behaviors and dynamics that will occur in the microgravity and

Earth's gravity environments, and to investigate systems in which the inertial effects are important on the length

scale of particles and bubbles.

TASK DESCRIPTION:

Complementary theoretical, simulation and experimental approaches to achieve the atbrementioned task objective.

The study will consider two types of inertial suspensions that are amenable to detailed theoretical studies. The t-trst

type is a solid-gas suspension, in which the inertia of the particle and the gas viscosity are more important than the

gas phase inertia. The second type is a suspension of bubbles with high Reynolds number indicating invicid flow,

but with small Weber number indicating that their deformation is small. Theoretical development of sheared

particulate and bubbly liquids will make use of concepts borrowed from the kinetic theory which has been

successfully applied to granular flows. The kinetic theory will be complemented by a numerical simulation of the

solid-gas and gas-liquid suspensions. These simulations include detailed calculation of the hydrodynamic

interactions among the particles in both microgravity and Earth gravity conditions. To validate the equation of

motion of the suspension systems, experimental measurements of suspension properties in simple basic flow

situations are necessary. The initial earth-based experiment will involve sheared fluidized bed by using capacitance

probes to measure the volume traction as a function of time, the shear rate required to overcome the gravitational

instability. The knowledge gained from the theoretical, simulation, and experimental work will set the necessary

background to propose low gravity experiments.

TASK SIGNIFICANCE;

Shearing fluidized bed and bubbly suspensions are used in chemical processing and understanding the dynamics and

flow behavior in these systems is crucial.

PROGRESSDURING FY 1994:

The aim of this project is to study, both experimentally and analytically, the flows of two suspensions with

significant inertial effects: the gas-solid suspensions with vanishingly small Reynolds number ana finite Stokes

number, St, and bubbly liquids at large Reynolds number. During the first three months of the project

(06/24/94-10/04/94), we have completed an analytic investigation of the simple shear flow of dilute gas-solid

suspension. We found that the suspension exhibits multiple steady states for range of values of St and the volume

fraction f. The final steady state depends on the initial conditions of the suspension. For sufficiently large initial

velocities, the final state, which we refer to as the ignited state, has a very large velocity variance, and for small

initial variance the final state is quenched with a vanishingly small final variance. A kinetic theory has been

developed to explain these and several other interesting results observed in the numerical simulations of the flow.

We are currently extending this theory to larger f and comparing it to the results of Stokesian dynamic simulations

of these suspensions.

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11446
II. MSADProgram Tasks -- Ground-based Research Discipline: Fluid Physics

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STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 5/94 EXPIRATION: 5/96

PROJECT IDENTIFICATION: 962-24-05-96

RESPONSIBLECENTER: LeRC

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11447
Dielectric and Electrohydrodynamic Properties of Suspensions

PRINCIPALINVESTIGATOR: Dr. Dudley A. Saville Princeton University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

This investigation focuses on understanding those electrokinetic properties of particulate suspensions related to the

so-called "electrohydrodynamic effect", specifically, the dielectric constant and electrical conductivity. These

properties are of crucial importance in defining the behavior of samples in various electrokinetic separation

processes. The work involves two research tasks:

1. Measurements of the electrokinetic properties of a series of suspensions with particle volume fractions between

1% and 20% by volume.

2. Development of a theory for the dielectric constant and conductivity of suspensions which encompasses the

measured behavior.

TASK DESCRIPTION:

Experimental work: We have been attempting to prepare model particles which conlbrm to the classical theory.

Previous research showed that with some particles annealing at 120 °C (above the glass transition temperature)

smoothed the particle surface so suspensions behaved according to the classical theory. Attempts to prepare such

particles using both anionic and amphoteric latexes purchased from the Interracial Dynamics Corporation, met with

limited success. The reasons for this behavior are not at all clear. Accordingly, we have been working to adsorb

polymer on latex particles to increase their dipole moment. Suspensions prepared with these particles will have

large dielectric constants which can be controlled by the amount and size of the adsorbed polymer.

Theoretical work: We continue to work on theoretical models of the electrohydrodynamic effect and on models of

the electrokinetic behavior of dispersions. The purpose of these efforts is to provide the requisite theory to interpret

our results.

TASK SIGNIFICANCE:

This research is intended to develop an understanding of one of the major obstacles to effective separation of

particles by electrokinetic methods. During the past year we uncovered ways of adapting our techniques to

understanding the behavior of particles in non-aqueous systems. Thus, in addition to its use in separations, our

work should find applications in ceramic processing.

PROGRESSDURING FY 1994:

During the past year significant progress was made as follows:

1. We successfully measured the dielectric properties of suspensions containing particles with adsorbed polymer

(polyethylene oxide). As expected these suspensions had significantly higher dielectric constants. They may

provide an excellent model system with which to study electrohydrodynamic effects.

2. The dielectric properties of concentrated dispersions were measured at volume tractions up to 30 %.

3. A theory for the macroscopic hydrodynamic behavior was developed (and published).

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11448
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 6/91 EXPIRATION: 6/95

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-08-08

MS Students: 0 MS Degrees: 0 NASA CONTRACTNO.: NAG8-878

PhD Students: 1 PhD Degrees: 1 RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Saville, D.A. Electrohydrodynamic deformation of a particulate stream by a transverse electric field. Physical Review

1,etters, vol. 71, 2907-2911 (1993).

Saville. D.A., Rosen. L.A. and Baygents. J.C. Dielectric relaxation in dispersions of colloidal particles with a dynamic

Stern layer. J. Chemical Physics. vol. 98, 4183-4194 (1993).

Presentations

Saville, D.A. "Dielectric relaxation in colloidal dispersions." Electrokinetics "93, Granada, Spain, 1993.

Savitle, D.A. "Electrohydrodynamic deformation of a particulate sample." AICHE Annual Meeting, St. Louis, MO.

November, 1993.

Saville, D.A. "The roles of dynamic processes behind the shear plane." International Colloid and Surface Science

Symposium, Adelaide, South Australia, February, 1994.

Saville, D.A. "Electrokinetic behavior of concentrated colloidal dispersions." ACS Colloid Symposium, Stanford, CA,

June, 1994.

Saville, D.A. "Dielectric relaxation in suspensions of particles with physisorbed PEO." ACS Colloid Symposium.

Stanford, CA, June, 1994.

1I--449
[I. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

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Electrohydrodynamic Pool Boiling in Reduced Gravity

PRINCIPALINVESTIGATOR:Prof. Benjamin D. Shaw University of California, Davis

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

Task OBJECTIVE:

To investigate the effects of electric fields on reduced-gravity pool boiling. The electric fields are expected to

significantly and controllably increase reduced-gravity nucleate boiling rates and maxtmum heat fluxes. The

presence of an electric field will result in the production of smaller bubbles in reduced gravity and the average speed

will be increased.

TASK DESCRIPTION;

A drop apparatus will be constructed for use at the NASA Lewis 2.2 Second Drop Tower. This apparatus will

consist of a pool boiling test chamber and associated instrumentation mounted on a NASA drop frame. Boiling

will occur on an electrically-heated platinum wire subjected to a nonunitorm external DC electric field. Boiling

experiments will R-113 (trichlorotrifluoroethane, (CC12FCIF_, for which tc>>t0 or water (for which t¢<<t+) will be

performed in both 1-g and _tg. Data will be gathered on applied electric fields and wire heat fluxes and temperatures.

High-speed motion picture photography will provide visual records of boiling phenomena.

TASK SIGNIFICANCE:

Anyone who has ever boiled water on a stove is familiar with nucleate pool boiling. Even though it is an everyday

event, scientists do not understand precisely how it works, because the Earth's gravity influences how bubbles form

and grow in boiling liquids.

NASA is interested in the results from this expenment, because boiling liquids generate bubbles which are very

efficient at transferring large amounts of heat. Finding new ways to dissipate heat from the space shuttle or future

manned space platforms will be vital to the success of long-term missions.

The potential benefits closer to home, including more effective air conditioning and refi'igeration systems, and

improvements in power plants that could reduce the cost of generating electricity.

PROGRESSDURING FY1994:

Funding for this cooperative agreement began mid June 1994. Future plans include the following:

July 1994 to July 1995: Construct pool boiling apparatus and conduct lg tests.

July 1995 to July 1996: Conduct reduced gravity tests in LeRC 2.2 Second Drop Tower in two 5-week

sessions, (50 to 100 drops are planned) and analyze and report results.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 7/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-97

MS Students: 1 RESPONSIBLECENTER: LeRC

PhD Students: 0

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I1--450
Transport Processes Research

PRINCIPALINVESTIGATOR:Dr. Bhim S. Singh NASA Lewis Research Center CLeRC)

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this task is to promote, toster, and enhance the quality and breadth of microgravity research

conducted in the discipline of fluid physics by advancing the understanding of thermal and mass transport processes

when buoyancy-driven convection is reduced or eliminated.

TASK DESCRIPTION:

The approach to achieving the task objective is to provide LeRC in-house support to assist sponsored principal

investigators in the conduct of their research (parucularly when that research can benefit from unique expertise or

facilities at LeRC), while guiding and assisting in the definition of flight experiments.

TASK SIGNIFICANCE:

This task will assist in program planning and outreach programs in the external community, and it will conduct

in-house research to advance the understanding of transport and interfacial phenomena through exploitation of the

microgravity environment.

PROGRESSDURING FY 1994:

A linear stability analysis on Marangoni-Benard convection in a liquid layer bounded by a free surface from below

and a free surface from above has been conducted for both non-deformable-free-surface case and

deformable-free-surface case. The results show that the instability is surface wave instability in nature, rather than

hydrodynamic instability. It is also shown that surface detbrmation changes the characteristics of the

Marangoni-Benard instability to long wavelength unstable. Oscillatory instability occurs only at near the long

wavelength end (k<<l), and that higher Prandtl number tends to reduce the domain of oscillatory instability. On the

experiment side, the bottom heater was upgraded by implementing two high-resolution thermistors, one at the

center and one at near the edge. A precision thermal controUer was also purchased and used. Initial experiments on

the Marangoni Instability in a liquid sheet with 2 tree surtaces are being conducted with a silicone oil layer

supported by a layer of FC75 from below and exposed to an air layer on top.

The coupled Marangoni-Benard/Rayleigh-Benard problem with temperature dependent viscosity was solved as a

numerical eigenvalue problem. In this study, the reference temperature is taken to be temperature of the bottom

surface and a linear (first order approximation) viscosity profile with respect to temperature is used. The temperature

dependent viscosity was found to be stabilizing for the Rayleigh-Benard Problem, the Marangoni-Benard Problem,

and the coupled problem. The linear viscosity profile was shown to be valid tor typical Benard studies of thin liquid

layers. The choice of reference temperature influence the variable viscosity effect. Results are currently being

summarized.

The performance of a spectral (Chebyshev collocation) lbrmulation of the benard problem has been compared with a

finite (central) difference tormulation of the same problem. Results of both discrete formulations are compared to

exact solutions of the Benard problem. The error of the spectral scheme is at least seven orders of magnitude

smaller than the finite difference error for a grid resolution of N=I 5 (number of points used).

In the area of thermocapillary bubble/drop migration, higher order asymptotic results for the bubble velocity have

been rederived following a slightly modified approach in the analysis of the outer temperature field. This was done

11-451
m response to comments from referees. Analysis was continued to determine the temperature field inside a

migrating drop when convective effects are predominant. Numerical efforts to model the same problem are also

under way.

Tests to examine capillary' driven flows in wedges and comers were continued using the drop tower. An analytical

model for capillary flow in comers was developed.

Measurement capabilities of the LeRC fluid physics laboratories were used to support multiple flight definition

PI's. Measurements of thermophysic',d properties e.g. surface tension of Newtonian and non-Newtonian fluids were

performed. Optical techniques were developed/improved to provide better flow visualization and quantitative

measurements. These include two- and three-dimensional particle image velocimetry and point diflraction

interferometry.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 2

MS Students: 0

PhD Students: 0

TASK INITIATION: 1/94 EXPIRATION: 1/95

PROJECT IDENTIFICATION: 962-24-05-01

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Balasubramaniam, R. Thermocapillary bubble migration: solution of the energy equation for potential-flow approximated

velocity fields. Japan Society for Computational Fluid Dynamics (in press), (1994).

Duh, J.C. Marangoni-Bernard convection in a low-aspect-ratio liquid layer. J. Microgravity Science and Technology, vol.

7, 98-102 (1994).

Proceedings

Skarda. J.R.L., McCaughan, F.E. and Fitzmaurice, N. "The Bernard Problem: A comparison of finite difference and

special collocation eigenvalue solutions." 6th Annual Thermal and Fluids Analysis Workshop, NASA LeRC/NASA

CP-1016I, August 1994.

Presentations

Duh, J.C.. Chien, L. and To, K. "Post-onset evolution of marangoni-bernard convection in a liquid layer heated from

below." 45th International Astronautical Federation Congress, Jerusalem, Israel, October 9-14. 1994.

Oron, A., Deissler, R. and Duh, J.C. "Marangoni instabilities in a liquid sheet." 30th COSPAR Scientific Assembly,

Hamburg, Germany, July 11-17, 1994.

Skarda, J.R.L. and McCaughan, F.E. "Coupled Mar_ngoni-Bernard/Rayleight-Bernard instability with temperature

dependent viscosity." ASME Winter annual meeting, Chicago, IL/NASA TM 106646, November 1994.

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11--452
Solute Nucleation and Growth in 5upercritical Fluid Mixtures

PRINCIPALINVESTIGATOR:Dr. Gregory T. Smedley Calilk)rnia Institute of Technology

CO-INVESTIGATORS:

Gerald Wilemski Lawrence Livermore National Laboratory

TASK OBJECTIVE:

We plan to study the behavior of napthalene in supercritical carbon dioxide due to the availability of thermodynamic

data for this system, the accessibility of relevant experimental conditions in the laboratory, and the importance of

C02 in many technological applications. The strong dependence of solubility on pressure enables the nucleation and

growth processes to be experimentally decoupled, so they may be studied independently.

TASK DESCRIPTION:

1. Determine experimental parameters for supercritical expansion processes. These include thermodynamic

process paths, equilibrium solubilities, particle size and growth rate estimates.

2. Make optical measurements of solid particle nucleation and growth rates in fluid mixtures of CO_ and

naphthalene that are initially prepared in a supercritical state.

3. Analyze experimental data. including phenomenological analytical modeling as necessary.

4. Develop and recommend a flight experiment design based on the results of the ground-based experiment.

TASK SIGNIFICANCE:

The experiments will employ rapid, but controlled, changes of the supercritical fluid pressure to vary the

thermodynamic state of the fluid from a stable condition to one favoring solute nucleation and then to one fostering

only solute particle growth. By using optical methods to measure the number of particles formed and their size, we

can determine nucleation rates and growth rates at various thermodynamic conditions. Since the rates of nucleation

of solid particles have never before been measured under these conditions, the data to be obtained will be invaluable

for testing and improving nucleation theory as well as for guiding the design of a space-based experiment. One of

the most important goals of the ground-based experiment will be to evaluate the effects of gravity on the measured

nucleation rates. Because the density of near- and supercritical fluids varies rapidly with pressure, gravity may induce

nonuniform conditions in the experimental fluid mixtures. This would make accurate ground-based measurements

difficult if not impossible.

The results of this experimental/analytical work can be applied to the understanding of nucleation and growth

problems found in many fields such as biotechnology (protien crystal growth), material science (sintered alloys),

and analytical chemistry (supercritical fluid extraction and chromatography).

PROGRESSDURING FY 1994:

The necessary contractual arrangements have been processed to fund this proposed research which was accepted under

the 1991 NRA. Funding began in August, 1994. The research effort has just been initiated.

STUDENTSFUNDEDUNDER RESEARCH: TASK INITIATION: 8/94 EXPIRATION: 8/97

PROJECT IDENTIFICATION: 962-24-05-69

RESPONSIBLECENTER: LeRC
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

I,|I,|II,IIDIIIII011,11_,IIII|,IHIISII_|I_|I,,I'mI,,II,,10IIHI,IIIt IIIIIOI''"II"IH _|I_Io_o_I_|IN_i_Iu_II_|_u_"_|_IlIt._i_III_IIl_1_g_IIt_I_lI_I|_uoI_II_HNI_Ii_Q_I_i_Ie_a_I_I_i_II_IIH_

Behavior qf Unsteady Thermocapillary Flows

PRINCIPALINVESTIGATOR:Prof. Marc K. Smith Georgia Institute of Technology

CO-INVESTIGATORS:

Prof. J.N. Koster University of Colorado

TASK OBJECTIVE:

The objective is to investigate thermocapillary instabilities to provide an understanding of the mechanisms of flow

instabilities. The study will also indicate how well the stability theory results for simple geometries apply to the

behavior of thermocapillary flows in more complex geometries.

TASK DESCRIPTION:

The research approach consists of both a theoretical and an experimental effort. Two nonlinear analytical models for

study of post-critical thermocapillary flows in a bounded domain will be constructed as part of the theoretical work.

The models will be used to explore the effects of Pr, interracial heat transfer, domain size, 3-D disturbances, and

interfacial deformation on system flow stability. An expertmental investigation of thermocapillary instabilities of

opaque, low Pr and high Pr fluids will be also be performed.

TASK SIGNIFICANCE:

This understanding will assist fluid system designers optimize system designs in which thermocapillary flows are

important.

PROGRESSDURING FY1994:

Theoretical Work:

In the second year of this project, we have continued our analysis of the behavior of the thermocapillary flow of a

liquid layer contained in a shallow cavity. Previously, we have used asymptotic techniques appropriate to very thin

layers to derive a nonlinear partial differential equation describing the evolution of the free surface of the liquid layer.

We have solved this evolution equation numerically for a two-dimensional steady flow. The solution is

parameterized in terms of a modified capillary number that measures the effect of surlace tension. For small

capillary numbers (large surface tension), the free surface of the layer is almost flat. As the capillary number

increases, the deformation of the interlace increases with a bulge forming near the cold end of the cavity and a

depression occurring near the hot end. This behavior is in keeping with asymptotic solutions found previously by

Sen and Davis (1982).

This year our numerical calculations have indicated that when the modified capillary number exceeds 43.3, no steady

solution exists. We have used an arc length continuation technique (the AUTO94 software package) to trace the

solution curve past this limit point. The curve doubles back on itself and indicates that Ior capillary numbers less

than the critical value of 43.3, there are actually two distinct solutions to the steady flow in the cavity. The

solution on the upper branch has much more interfacial deformation than the lower branch. For the smaller values

of capillary number, the delbrmation reaches the total depth of the layer and so we must stop the calculations

because the layer most probably ruptures. Our evolution equation does not apply in this situation.

We have also done a stability analysis of the steady solutions on this entire solution curve. The solutions on the

lower branch, in which the deformation is smaller, are linearly stable. The solutions on the upper branch are

linearly unstable.

Our current direction is to do a time dependent calculation of the behavior of the layer. One can easily speculate that

for the unstable upper branch, the layer will move toward the stable branch solution/'or the same capillary number

_s_III_Ie_I_Do_It_I_i_I_i_I_e_B_I_e_e_I_I_I_I_i_i_e_Ij_o_jI_j_I_e_I_I_II_I_1_1it_I_I_*

11--454
when the layer is disturbed. However, 10r small v',dues of the capillary number it is possible that the layer could

increase its deformation and approach a ruptured state in which liquid is contmned in each corner of the cavity and a

dry spot appears in between. For larger values of the capillary, number where steady solutions do not even exist, an

initially uniform liquid layer will most probably deform continuously until it either ruptures in the middle or it

comes to a new state in which the thin-film physics forces the layer to remain continuous. The appropriate physics

required tor this behavior has yet to be included in our mc_Jel of the liquid layer.

Experimental Work:

The experimental work has been conducted at the University of Colorado at Boulder under the direction of Prof. Jean

N. Koster. The experiments using optical techniques on silicone oils have been completed. The optical test cell is

an open, rectangular container in which the liquid layer measures 92 mm long by 15 mm wide. The two ends of the

cell are copper and are held at different fixed temperatures. The lower surface is PVC which simulates an insulated

surface and the side walls are made of glass. The container was filled with a layer of silicone oil starting at a depth

of 1 mm and increasing up to 4 mm in increments of 0.5 ram. This oil was driven in a thermocapillary motion by

the temperature difference of the ends of the cell. Two different oils were used; their Prandtl numbers were 8.5 and

27.5. The tree-surface deflection of the layer was observed by means of strioscopy.

The results of the experiments showed that an instability occur for a temperature gradient across the layer above a

critical value. For small layer depths, the instability takes the form of a regular train of waves propagating from the

hot end to the cold end. These may be an example of a hydrothermal wave predicted by Smith and Davis (1983a).

For larger depths, an irregular train of waves appears that "also propagates in the same direction. The critical

Marangoni numbers for these transitions are higher than the theoretical values computed by Smith and Davis

(1983a). The discrepancy is probably due to the neglect of gravity in the theory and the different geometry of the

experiments.

The flow patterns in the layer were visualized by seeding the layer with parucles and taking streaktine photographs

of the flow. For a thin layer and with the imposed temperature gradient just less than the critical value, the flow

field takes the form of a multi-cellular steady state. When the temperature gradient is greater than the critical value

and the regular wave train appears, there seems to be no change in the multi-cellular flow field inside the layer. For

a thicker layer and with the imposed temperature gradient just less than the critical value, the flow field takes the

form of a single, steady recirculation cell and a much smaller cell near the hot end. When the temperature gradient

is greater than the critical value the irregular wave train appears and a transient behavior of the recirculation cell is

observed.

An attempt to use holographic imaging to visualize the flow instability in the layer was made. The results were

not very successful because large temperature gradients and the convective flow in the layer would produce

significant distortions in the hologram. In the low-viscosity silicone oil layer, the temperature gradients and

convective motions were reduced and so some success was achieved. The advantage of using holography is the

much higher resolution lor the visualization of small free-surface deformations. This increased resolution detected a

second instability in the layer in the form of an intermittent wave with a wave speed about twenty times larger than

the previous wave-like instability. It may be an example of a surface wave predicted by Smith and Davis (1983b).

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 1/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-62

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

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11455
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Sen. A.K. and Davis, S.H. Steady thermocapillary flows in two-dimensional slots. J. Fluid Mech, 12l. 163-186 (1994).

Smith. M.K. and Davis, S.H. Instabilities of dynamic thermocapillary liquid layeers, part 1, convective instabilities. J.

Fluid Mech, 132, 119-162 (1994).

Smith, M.K. and Davis, S.H. Instabilities of dynamic thermocapillary liquid layers, part 2, surface-wave instabilities. J.

Fluid Mech. 132, 145-162 (1994L

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!I-456
Flow-Influenced Shape Stability: Breakup in Low Gravity

PRINCIPALINVESTIGATOR: Prof. Paul H. Steen Cornell University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

1. Understand the influence in low gravity of flow on interface shape. For example, document and control the

influence of axial flow on the Plateau-Rayleigh instability of a liquid bridge.

2. Extend the ground-based density-matching technique of low gravity simulation to situations with flow; i.e.,

develop Plateau chamber experiments for which flow can be controlled.

TASK DESCRIPTION:

The configuration of a liquid held by surface tension under low gravity is susceptible to significant modification by

liquid motion. Motion destablizes in general but there are narrow circumstances where motion can stabilize. We

identify these circumstances theoretically, by solving linear and nonlinear stability problems, and try. to locate them

in experiments conducted with a dynamic Plateau apparatus. Overall, the goal is an understanding of the influence

of flow on shape.

TASK SIGNIFICANCE:

Containerless containment of liquids by surface tension has broad importance in low gravity. For space vehicles,

the behavior of liquid/gas interlaces is crucial to successful liquid management systems. In microgravity science,

tree interfaces are exploited in various applications. Examples include float-zone crystal growth, phase separation

near the critical point of liquid mixtures (spinoidal decomposition) and quenching of miscibility gap molten metal

alloys. In some cases, it is desired to stabilize the capillary instability while in others it is desired to induce

capillary breakup. In all cases, understanding the stability of interlace shape in the presence of liquid motion is

central.

PROGRESSDURING FY 1994:

Both analytical/numerical and experimental approaches are employed.

Stability analyses include linear and nonlinear techniques. The linear stability approach has been used to analyze the

shape stability of a _ hndrical interlace containing axial shear flows, both isothermally and thermocapiilary-driven.

Computational feasibility currently limits this approach to base states that are separable flows, effectively, the

axial-infinite interlaces. It is now well-known that infinite cylindrical interlaces can be stabilized. For finite

interfaces an alternative approach is needed. In the limit of no motion, minima of the tree-energy functional are

obtained using the calculus of variations supplemented by numerical branch-tracing. For weak motion (creeping

flow), we extended this approach below using a modified functional. Near the singularity represented by the

Plateau-Rayleigh limit, bifurcation theory using Liapunov-Schmidt reduction is a natural tool for the solution of

the appropriate nonlinear Euler-Lagrange equation. All these analytical/numerical tools lend themselves to

understanding the physics of stability in terms of simple competition mechanisms.

As for the experimental approach, a dynamic Plateau chamber has been built and is used to study liquid bridges held

captive by red-ends and embedded in a controlled surrounding flow. Theory has guided the experiments to a

particular window in parameter space. Such gut 'dance is crucial since interesting stabilization effects occur over

narrow parameter ranges tor this problem.

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I1-457
II. MSADProgramTasks--Ground-basedResearch Discipline:FluidPhysics

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Theory results:

1) Stability (instability) of a static bridge equilibrium (B - 0) is immediate once the family of equilibria to which

it belongs is identified; direct calculation of the second variation is circumvented.

2) All known families of static bridge equilibria (B - 0) are ultimately connected and thereby inherit their states of

instability (number of unstable modes) ultimately from the stability of the sphere.

Experiment results:

3) A comparison of pairs of relatively immiscible liquids suitable for use in a dynamic Plateau chamber with

density balance within 104 g/cm 3has been presented. Pure water and the isomeric system of 2-, 3- and

4-fluorotoluene is one preferred pair. Pure water and the homologous system of chlorocyclohexane and

chlorocyclopentene is another.

4) Further observation of analysis of the collapse of the soap-film bridge have been performed. The soap-film

collapse is viewed as a prototype collapse.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 1/96

BS Students: 1 BS Degrees: 0 PROJECT IDENTIFICATION: 962-24-05-57

MS Students: 0 MS Degrees: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1 PhD Degrees: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Lowry, B.J. and Steen, P.H. Stabilization of an axisymmetric liquid bridge by viscous flow. Int. J. Multiphase Flow, 20

(2), (1994).

Lowry, B.J. and Steen, P.H. Flow-influenced stabilization of liquid columns in a dynamic plateau chamber. AIAA paper.

93-0255, (1993).

Lowry, B.J. and Steen, P.H. On the density matching of liquid using plateau's method. AIAA paper, 94-0832, (1994).

Proceedings

Chen, Y.J. and Steen, P.H. "Influence of flow on interface shape stability." Proceedings of the 24th IMACS World

Congress. Atlanta, CA, July 1994.

Presentations

Lowry, B.J. "Ph.D. dissertation." Cornell University, Ithaca. NY, 1994.

Lowry, B.J. and Steen, P.H. "Capillary surfaces: stability from families of equilibria with application to the liquid

bridge." Proc. Roy. Soc. A, accepted.

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1I--458
Interactions of Bubbles and Drops in a Temperature Gradient

PRINCIPALINVESTIGATOR: Prof. R. S. Subramanian Clarkson University

CO-INVESTIGATORS:

Dr. R. Balasubramaniam NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The objective of this research is to study the interactions of bubbles and drops in the presence of a temperature

gradient m the continuous phase. The goal is to understand how the presence of a neighboring drop "alters the

motion of a test drop and whether the two drops coalesce. Both theoretical and experimental research is planned on

the interactions of drops with each other or with a neighboring boun "dary.

TASK DESCRIPTION:

The emphasis of the initial effort is on the design, fabrication and set up of the experimental hardware, and to check

its performance. Experiments will then be performed using a suitably chosen liquid-liquid system such that the

drops sink due to buoyancy. The drops will be subjected to a vertical temperature gradient; thermocapillary forces

will then cause the drops to move upwards. Initially experiments will be pertormed with single drops and the

results will be compared with existing theory. Subsequent experiments will locus on drop interactions.

TASK SIGNIFICANCE:

This research attempts to provide important information on interactions of drops, i.e., how the presence of a drop

affects the motion of another, in a medium where the temperature is non-unitorm. Primary emphasis is on

thermocapillary flow, thereby the research is more applicable to drop interactions under reduced gravity. The nature

of these pairwise interactions determines whether the drops speed up or slow down as they approach each other and

whether they collide or glide past each other. Pairwise interaction data are very useful in models that track

coalescence in a many drop dispersion.

PROGRESSDURING FY 1994:

Experiments have been conducted on the motion of single drops of diethyl maleate in 1,3 - propanedial. The drop

sizes ranged from 0.04 to 0.65 mm and the upward temperature gradients from 0.045 - 2.4 K/mm. The results from

these tests clearly demonstrate thermocapillary effects - the drops sink due to buoyancy when the gradient is low _md

rise when the gradient is high. Dissolution of some species from the drop fluid into the outer fluid has been

observed and steps have been taken to minimize its impact. For situations where the convective transport of energy

is negligible, the data is in agreement with theoretical predictions. New theory is needed to compare with the

experimental results with significant convective energy transport effects.

A new test cell has been designed and constructed. The design accommodates the insertion of parrs of drops and

viewing their motion from two orthogonal directions. Preparatory tests to check the performance of the test cell are

under way and interaction studies are expected to commence soon.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 3/93 EXPIRATION: 2/96

PROJECT IDENTIFICATION: 962-24-05-58

RESPONSIBLECENTER: LcRC

11--459
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

, |,, I I * t t o | I oo ! III I * i a | | * I | |! || | e to o I ! | ! o o ! !I o ! ! f ! I o o o I o I I o ! I oo *, I i | i a o o a ! ! mu o i |, I o o I i * I Iq I o I I * iio o Io I t * o I I o I I o I, o Ia o | o o o * | o I o o * I I t _ I oI * o o * I * I I | o o i * o o o ** a I I * I i i o i i ona * | a o I o I o o | || | |o g | I ! o I aOl I * |1 on a oil *H *oI o !|m o H I OOI H I oomoo I, u ! o o OOIO Ia o 0SO I o o

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Lacy. C,E., Subramanian. R.S., Balasubraminian. R. "The behavior of drops in a vertical temperature gradient - influence

of convective transport of energy." to bc presented at the AICHE 8?th Annual Meeting, San Francisco. November 1994.

nmII IO! OIIO O011 OI Ill O| amIOl nl OooOIl ol! oil| Ill IlI 1| I II I OIl 0IgI l! OIl II O¢1 OOI UOO0OI OO|ll Ill II Stl Oil OIl Oil I Oil ¢II Ill IOI OII O0! loll IO OSLOSH| nO Hi UI1! OOll nil el ! IO! it! OIl oil| lie Ill lie l! |lO IlO I I! I I! I I ! l! Olog Oolll ! I I! I I! nil0! O0! M OIl OOH |l! It! Ol! Oil O

11460
11. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

ill i i i i i i l lllll Ill II III I III I Ill I i Ill i If i IIII I I I III I III l I I I, I Illlllllll I I I I III III I I llll III III III I IIIlll II Ill I tl I I I I I III I II IIII I Ill I llllll I I I lll I llll I I II III Ill I II I I III III Ill U Ill I I lllll I I lllll IllS lUll I I IIllllnlU I IIlIItlllll III I Ill I IIIII I III Ill

Instability in Surface-Tension-Driven Benard Convection

PRINCIPALINVESTIGATOR: Prof. Harry L. Swinney University of Texas, Austin

CO-INVESTIGATORS:

Prof. W.D. McCormick

Prof. J.B. Swift

University of Texas, Austin

University of Texas, Austin

TASK OBJECTIVE:

The objectives of this work are to investigate the primary and secondary instabilities in surface-tension driven

convection and in double-diffusive convection in the Hele-Shaw geometry, and to characterize both the global

structures and the local flow properties of Bemard Convection.

TASK DESCRIPTION:

Noninvasive optical techniques will be developed and employed to study the primary and secondary instabilities over

a wide range of Marangoni numbers. Theoretically, nonlinear analyses for the long wave (k=0) instability will be

conducted with surlhce deflection included. Direct numerical simulation of the two- and three-dimensional

incompressible fluid equations will be used to investigate both weakly non-linear behavior near the primary

instability and secondary instabilities in Marangoni convection.

TASK SIGNIFICANCE:

Surface tension force dominates many physical processes in space and strongly influences many important practical

problems on Earth, such as the processing of commercially important materials (electronic or biological crystal

growth), manufacturing (welding, coatings), as well as industrial heating, cooling, and mixing (thin film heat

exchangers). This work seeks to elucidate clearly the basic mechanisms that can cause fluids to change from a

simple quiescent state to a turbulent behavior. Such a transition can have a dramatic effect on the practical

problems described above. Furthermore, in the course of this work, new experimental techniques such as the

enhanced inli'ared imager will be developed that may later find wider use in other space/terrestrial applications of

commercial importance.

PROGRESSDURING FY 1994:

In FY94, experimental evidence was obtained for the existence of hysteresis at the onset of hexagonal convection.

These results suggest that the primary instability in surface-tension-driven Benard convection can occur as a

subcritical bifurcauon, as predicted by theory. Surface temperature distribntion in Benard convection is being

measured using a state-of-the-art infrared imager. Techniques were developed to optimize the spatial and

temperature sensitivity of the measurements. A new apparatus was designed and built to permit infrared imaging

of the flow field while maintaining good temperature control in the convection cell. In addition, the long

wavelength instability in Benard convection, which may dominate in microgravity, was investigated theoretically.

A nonlinear evolution equation in two-dimensions was derived; moreover, all analysis of this equation demonstrates

the primary bifurcation to the long wavelength mode occurs subcritically lbr all parameters investigated. Use of a

purified single component silicone oil was demonstrated to eliminate deleterious evaporation/condensation effects in

the experiment. A protocol for systematically purifying commercial silicone oils lot use in convection experiments

is being investigated.

11-461
IT. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

ii g | i a ! i g i i iJ |i t ! i i | ! i | _ I | _ I I ¢ i | 6 | | i g ii | I Iq * i q o | I * | Io |I a | i i | 11111 e I Io |I o Dt e i t g I t ! t i| t Pi I I o 16 o a I i g | | iii i e i i a | | I I t I| i g | I t | | a e I I o | I |! ! ! ! ! ! t I _ J I !J! I It I e II o i i i I _ II ¢ J I I I t I _ _ i i_ | _| | | | * | | _ _ I I _ i I _ I! * I! * i _ _ | I o _ I o _¢ t t i ! t i ! _ I I _| ! I Ia | ¢ _ |_ ! D|i _! ! _ H H _ H t_

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/95

BS Students: 4 PROJECT IDENTIFICATION: 962-24-05-41

MS Students: l RESPONSIBLE CENTER: LeRC

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Schatz, M. "Onset of hexagons in surface tension driven Benard convection." 2nd Microgravity Fluid Physics

Conference, NASA Lewis research Center, June. 1994.

Schatz. M. "Benard convection: New experimental techniques." Texas Section of the American Physical Society,

October, 1994.

Schatz, M. "Infrared Imaging of temperature in Benard convection." Annual Meeting of APS Fluid Dynamics Section,

Atlanta. GA, November, 1994.

VanHook, S. "Long Wavelength thermocapillary instability in Benard convection." Annual Meeting of the APS Fluid

Dynamics Section, Atlanta, GA, November. 1994.
Crystal Growth and Fluid Mechanics Problems in Directional Solidification

PRINCIPALINVESTIGATOR:Prof. Saleh Tanveer Ohio State University

CO-INVESTIGATORS:

Dr. G. R. Baker

Dr. M. R. Foster

Ohio State University

Ohio State University

TASK OBJECTIVE:

The primary objective of this task will involve efforts to build a comprehensive theory for dendritic crystal growth,

with and without fluid convection. This is a difficult task as it involves a nonlinear time-dependent evolution

equation that is nearly ill-posed when capillarity effects are small. Bridgman Crystal Growth situations will also be

studied.

TASK DESCRIPTION:

The eftort will primarily consist ot a numerical study of possible bifurcation of steady-state solutions that may be

steady or oscillatory in two or three dimensions.

TASK SIGNIFICANCE:

It is expected that some interesting subclasses of problems will be found lor extreme values of parameters; in these

cases, it is possible that the essential phenomena can be captured by a nonlinear analysis of equations that contain

only a few parameters.

PROGRESSDURINGFY 1994:

During the funding period of support, Jan 1994 to present, continued progress has been made in two different crystal

growth problems - dendritic crystal growth and the Bridgman problem.

A. Dendritic Crystal Growth

In the small Peclet number asymptotic limit, we have carried out both numerical and asymptotic analysis with a

view to understanding some controversial issues in selection theory and in the time development of dendrites.

If we recall, in studying certain classes of disturbances superposed on an initially parabolic dendrite, in the

asymptotic limit of small Peclet number Pe, it was recognized that there are different regions where the equations

Ibr the temperature field and boundary conditions have different torms. In an 0(1) region around the dendrite tip, the

diffusive field reduces to a Laplacian. With a novel numerical scheme, we have computed highly accurate solutions

in the tip region showing the evolution of an initially parabolic dendrite with nonzero surlace tension. For a long

time, perturbation from the initial parabola is found to be restricted to the 0(1) region surrounding the tip, while the

other regions play a passive role and remains steady. It was found that regardless of the initial condition, a bulbous

expanding region lbrms near the tip in the absence of crystalline anisotropy. For long time, this bulbous region

evolves in a way independent of the initial condition. In the presence of noise, represented in our formulation by

certain complex singularities, this bulbous tip region will split. The calculation suggests that there can be no

globally time dependent state with a locally steady tip. However, with an assumed four-told crystalline anisotropy,

with a minimal surface tension direction coinciding with the needle crystal axis, it is lbund that the tip region

settles to a steady state where the tip radius and velocities are in accordance to microscopic solvability. This

happens within the time scaie where disturbances have not moved away from the 0(1) region around the tip.

A family of exact solutions describing the time evolution of a zero surface tension dendrite in the 0(1) tip region

was reported last year. Some of these solution exist for all times and result in tip-splitting or side-branching of an

initially nearly parabolic dendrite. Later on, a criterion involving the sign of the real part of the residues of poles

11-463
lI. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

m _t JBp_lml _J! I_0_ PI pss _DImIJIm J gmJ I _JI I PJ I_J J _! Sl mI I_llm J J _l ! m S_ _BI! _m_ l0 J J _ J J _JI PI J JJ t0 J 01 m J J_ _ J mJ_B _0S J J I| J 0 J J _J_a_ _| | _ ! | J ! _! | 0_ _ _ _ I| _ _ | |; I I |10 _ _| | | _ g a | I 0 n n n O_ U00 O011 ! 0! a OW0* |1 O0, *_ | O01 | l0 ! I O| OU| 000O U|Oa _o a o ol o oa |_oo H! o o a _o i | |ao _1

was found that determined the side of the needle crystal on which disturbances advect. Some of these exact solution

result in a finite-time cusp singularity on the interface. We have addressed the relevance of some of these solutions

to the actual evolution of a dendrite in the small surface tension, small Peclet number limit. For instance, through

an inner region analysis, it was found that the time at which a zero surface tension solution forms a cusp is preceded

by the effect of the so-called daughter singularities that result in tip fattening in the absence of crystalline anisotropy

effects. The actual interlace in such cases does not come close to cusp tormation even for arbitrarily small surface

tension. In the presence of anisotropic small surface tension, a cusp does not torm either but in this case a locally

steady solution results when the anisotropy axis is aligned appropriately.

The fate of various types disturbance advecting along the sides of a needle crystal, as represented by certain types of

complex singularities approaching but never hitting the real domain, is also being examined. In particular, it is

seen that tbr an approaching complex pole, significant surface tension effects on the interface occur in a slow time

scale that scales inversely with the surface tension parameter. For sufficiently small Peclet number relative to

surface tension, such effects can be felt at the interface in the 0(1) region around the tip. For other relative ordering

of surface tension and Peclet number, surface tension effects are only felt once the disturbance has advected to other

asymptotic regions. The interaction of multiple singularities and their implication to side branching coarsening is

currently being examined.

B. Bridgman Crystal Growth

In the Bridgman problem, we investigated analytically the limit of large solutal Rayleigh number in the case when

the rejected solute is heavier that the rest of the alloy, i.e. in a solutally stable arrangement. Unlike the case of

large thermal Rayleigh number reported last year, where to the leading order the expressions for radial segregation

and crystal melt interlace do not involve the heat transfer at the top edge of the insulation zone, we rind that in this

case the heat transfer at both the top and bottom edges of the insulation zone is involved in the explicit expressions

for radial segregation and crystal melt interface shape, We also find some criteria to minimize each of these

quantities.

Accurate numerical schemes are being developed to extend and verify the asymptotic scaling results found

analytically. In addition, the transient problem that is free of any quasi-steady hypotheses is also being investigated

numerically. The numerical results for the quasi-steady equations, so far only with the linearized equations but a

more realistic no-slip side wall condition, are in accord with the asymptotic results in the large thermal

Rayleigh-number limit, where a more mathematically convenient no-stress condition was used. The calculations

also • demonstrate clearly the efficacy of the optimal heat transfer condition suggested analytically.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/96

PROJECT IDENTIFICATION: 962-24-05-53

NASA CONTRACT NO.NAS1-]8605

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Tanveer, S. Convection effects on radial segregation and crystal-melt interface in vertical bridgman growth. Phys. Fluids,

6. 2270-2292 (1994).hase-field models for solidification. Physica D69, 189-200 (1993).

Presentations

Tanveer, S. "Crystal growth and fluid mechanics problems in directional solidification." NASA Lewis Workshop, June

1994.

I1--464
II. MSADProgramTasksh Ground-based Research Discipline: Fluid Physics

,,, a, ! o 4 o o a | | a, ! a o i a * n a o I Io Ia o Da,, * i,, |, i i* |; o, o * o, a o | i | | o o| i i* | ! J | | I,, * o I i, ia t i a o I ! o o a i ! *o, o o, i o,, I, ii ! o i ! o i ! o o ! * |! a u ! a | ! o i, i a* I iI o ! o | * I i i i o ! o o * ! i o o* I o * I | I o IIi i i I* I a I o o o o I o I * H g | _ I * I i o | o i o * a Iii * i _ u ! * is nI * I |o ! u ! i. |a * H _ 01 o _ a. ! H Io, * Ho !, o oo a o I

OscillatoryChaotic Thermocapillary Flow Induced by Radiant Heating

PRINCIPALINVESTIGATOR:Dr. Robert L. Thompson NASA Lewis Research Center ('LeRC)

CO-INVESTIGATORS:

Prof. K. DeWitt

Dr. K. Hsieh

D. Van Zandt

University of Toledo

NYMA, Inc.

ADF

TASK OBJECTIVE:

The main objective of the research is to study the oscillatory and chaotic thermocapillary flows induced by radiant

heating of the tree surface of a high Prandtl number fluid. Both ground-based experiments and numerical analysis

will be conducted to study effect of heating level (supplied by CO2 laser), surface shape, aspect ratio, and Prandtl

number on the conditions lot transition from steady to oscillatory flows and then to chaotic flows. In the

experiments, flow structures will be observed using a flow visualization technique and temperature distribution on

the tiee surt'ace will be measured using an infrared (IR) imager. Numerical results will be compared with

experimental data.

TASK DESCRIPTION:

A CO2 laser is used to provide the heat source. The profile of the laser intensity in the radial direction can be a

Heaviside function or a Gaussian function with variable beam diameter. The material of the test chamber is a

copper water jacket, providing well-controlled wall temperature. The bottom wall of the test cell is insulated. An

IR imager is used to measure surface temperature distribution and several thermocouples are implanted in the test

chambers, including one at the bottom. Critical powers of the CO2 laser at the onset point of oscillatory flow are

measured at various aspect ratios and dynamic Bond numbers.

TASK SIGNIFICANCE:

The strategy of this study is to first compare the measured onset conditions/'or oscillatory flows with results from

linear stability analysis. With the designed experimental conditions, surface tension and buoyancy effects are

equally important. If close comparison between experimental and numerical results can be obtained, it could

support the validity of numerical prediction of the onset conditions for pure Marangoni flow. This can help the

design of possible space experiments. Results obtained in this study can help the design of surface tension driven

convection experiments in space. Furthermore, a deeper understanding of the thermocapillary flow can be achieved,

and the knowledge can be used to improve materials processing procedures.

PROGRESSDURING FY 1994:

In the study of onset conditions of oscillatory Marangoni flow in laser-heated silicone oil in a cylindrical container,

experimental data were obtained for various aspect ratios and dynamic Bond numbers. It is found that tbr a fixed

aspect ratio, there seems to be an asymptotic limit of the dynamic Bond number beyond which no onset of flow

oscillation could occur. Experimental results also suggested that there could be a lower limit of the aspect ratio

below which there is no onset of oscillatory flow. In parallel, a numerical program/or flow instability analysis has

been developed to predict the onset of flow oscillations.

i i i i, na, i!, oi, i i, i i, i o, ii, i i, I in | ol Ol i i o, i I. is* I o, i oi i i i oii 11 u, Ill I I' I' I I I I I IIII III I n l in OIll I I IlI I I I III I I,I, I I oI I Oil I I I I I III III I O,I ,|l, ! I, I II O|,! I OI Ill l,,, I1, I 11Ill O1, , I I I o, I, I I I Ill loll ill i in i Oi i Oi iii Oi ii ii i iii i i i ii Oii Otl Oii I ill ii Oi ii iOOill i i i

1I--465
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

I I !! e ! | I a III ! | t I IHe J t! it! o H I la o l! 4;i tii |IIt l! e lit ii; Ii I I t q i iq t Ii o Di i | i | | t Q| i io iI | | i a Iii * i i t | i |t i| | t I | ta .! o |! * l! i; i J | i | | i |; ! i | i a i i ! iii e n i !Qi t i ill | i i i nl i| | i i i i i t i i i | i _i i i I i i e i i t | i i i i| * ii i i i | i i | ii; Qi_ _ i _ I t i _ i i Qi i_ ni _ i i _ i a _ i it i i_ i i i i n _ i iQ i i| i i _ n

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/92 EXPIRATION: 10/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-67

MS Students: 1 RESPONSIBLECENTER: LeRC

PhD Students: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Hsieh, K.C., Thompson, R.L., DeWitt, K., Nash, J. and Van Zandt, D. "Oscillatory/chaotic thermocapillary flow induced

by radiant heating." 2nd Microgravity Fluid Physics Conference. Cleveland. OH, June 1994.

iI I Ill tie I I | I ! | I¢ I | | I I I * i I # I 0 t Io IIi I I | i | | t I | _ I I | | I ! ell e I| o | | I o i * I I0 i* I I t | | I QI I, I II e Iis Ii | | t i iii I eI ill e lle i e i I I I |t I | I i | I O! I Q| tI * III I I | I ! e |I I |I I | I I; I I e I I I; I e |I | | I I I| Qll! |OI I I I | I I I t I e ill II OI e ! I I I | t I It | II | | I I I SI * II I I| I I Q|l I | I| | I | | I | I ! I ! Io | i * I O| t QII

I1-466
Light Scattering Studies qf Relative Motions of Solid Particles in Turbulent Flows

PRINCIPALINVESTIGATOR: Prof. Penger Tong Oklahoma State University

CO-INVESTIGATORS:

Prof. W.I. Goldburg University of Pittsburg

TASK OBJECTIVE:

The primary objective of this task is to understand particle concentration fluctuations in turbulent flows, and in

particular how the dispersion is affected by particle inertia and the charterictics of the turbulence.

TASK DESCRIPTION:

This proposal describes a series of experiments on the dispersion of particles in turbulent flows. This task plan to

study the particle dispersion phenomena in two well characterized turbulent flows. One is turbulent

Rayleigh-Benard convection in water and the other is a turbulent grid flow in a water channel.

TASK SIGNIFICANCE:

The proposed research will add extremely tmportant data to that presendy available to develop understanding of the

interaction of solid particles _md a turbulent fluid. Such data would be valuable not only in revealing

phenomenoiogy, but also in testing model representations of turbulent suspensions.

PROGRESSDURING FY 1994:

This is a new grant formally began on July 1, 1994. Necessary advertising and hiring arrangements have been

completed to hire a post doctoral associate, who is expected start to work on the project in three months.

Meanwhile a new experiment is initiated in Dr. Goldburg's laboratory to study the motion of heavy particles in a

turbulent rotating Couettee flow. An undergraduate student in Dr. Tong's laboratory is involved in a study of

sedimentation of colloidal particles using a newly developed dual-beam incoherent cross-correlation technique.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-98

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 1
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

i i J t n i |ii I I nii i ! _ i i J | I n_ ii iiI e i i g i i | I n io II i I n I t n I o | t I i i iJ | It I i e n i i i i | i i Ii i i i i i i i i I I ii II I| I o I g i I i |I g i i I I! m| II I H o Doo ! i | | ! I i H I | | II i|l i i i | 11 t DI I I tl o D! |i i g ii I J I! I I I III I I i i | I ! ! J i I I i| |1 * I I I | III Io I Io i! _ I ! o I ! I in o I! e i ! o Iii i I I Ila IIi | ii | I | III i i! | iiI | I | i i

Computational Studies of Drop Collision and Coalescence

PRINCIPALINVESTIGATOR: Prof. Gr6tar Tryggvason University of Michigan

CO-INVESTIGATORS:

Dr. D. Jacqmin NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

The objective of this research is to investigate the behavior of bubbles and drops in microgravity by lull numerical

solutions of the governing equations. The collision and thermal migration of drops are studied in detail to provide

essential input for material processing and fluid handling in space. These problems also serve as a test bed for

refinements and extensions of the numerical technique being used, thus helping to develop the capability to predict

accurately the behavior of free-surt_ce fluid systems.

TASK DESCRIPTION:

A numerical technique, based on explicit tracking of the interface between two immiscible fluids, is used in this

study. This method has now been extended to deal with both the thermal migration and the rupturing of thin films.

TASK SIGNIFICANCE:

The unique aspect of the method is that it accounts fully for both inertia and viscous effects in both fluids and

allows the inclusion of surface tension. It is also well suited for complicated interface geometries and has been

implemented tbr tully three-dimensional flows. The basic aspect of this method is described in the Journal of

Computational Physics, vol. 100 (1992), p. 25.

PROGRESSDURING FY 1994:

Our research is aimed at developing a basic understanding of the behavior of drops in microgravity and developing

numerical tools to allow accurate predictions of their behavior. We have been lbcusing mainly on two

problems: Collision of drops and thermal migration of both bubbles and drops.

For collision of drops we have simulated the head-on collision of two equal size drops for a wide range of Weber and

Reynolds numbers, which are the main controlling parameters, as well as several fully three-dimensional off-axis

collisions. The simulations reproduce experimental data well, showing that the evolution of the drops depends to a

large degree on the Weber number of the drops before collision, but only weakly on the Reynolds number, once it

becomes sufficiently large. One of the more critical questions about drop collisions is whether the drops coalesce

permanenly or separate again. Several collision modes are possible, and we have examined a number of them. For

head-on collisions the drops deform into a disk-like shape as they hit each other and may separate again as surface

tension pulls this disk shape back into a more spherical form, often leaving one or more drops in between the

original drops. For off-axis collisions, the drops, on the other hand, may continue on their original path after the

initial coalescence, and stretch apart again (usually called "grazing collision"). The simulations reproduce these

modes well and have clarified a number of points, including the role of dissipation and the role of rupturing of the

film between the drops on subsequent evolution.

Our simulations of thermal migration have focused on the collective behavior of many drops as they migrate toward

a hot surface. We did several two-dimensional simulations during the first year, to gain experience with our

numerical method and to establish a "feel" for the problem. These results showed a strong tendency for many

drops to form layers across the channel, and also that the drops only deformed during the initial transient. Recently,

the focus has been on the three-dimensional counterpart. These results show that, for a given Ma, the drops do not

line up across the channel as rapidly as the two dimensional computations did. Since all interactions fall off much

more rapidly in three dimensions as compared with two-dimensions, this is perhaps not too surprising. However,

1_n_n_t_o_n6nu_nq_D_ot_nt_e_n_n_Q_e_t_no_tut_nu_enouj_N_n_1n_I_nene_D_nnn_e_o_n_e_I_tut_j_e_e_t_Do_Q_u_t_

11-468
a_sthe Marangoni number increases, the eflect of the drops on the temperature field increases and the interactions

become stronger. We are currently investigating the influence of Ma and other governing parameters, as well as the

volume traction, on these interactions.

During the la_styear we have _dso initiated work on the behavior of drops in a shear flow. This 'allows us to

examine the effect of the ambient t]ow on the drop behavior. We have done an extensive set of two-dimensional

simulations and a few three-dimensional ones of the evolution of a layer of drops initially near a wall. The

simulations show that as the drops mteract the layer breaks up and the drops fluidize as they collide with each other.

The rate of fluidization depends strongly on the Weber number which, for this problem, is the ratio of collision

time and the tune it takes the drops to be advected past each other.

The above computations have all been clone using explicit tracking of the boundaries between fluids. Although the

method is robust and accurate, it is somewhat complex and for many problems it may be possible to use capturing

- where the interface is simply marked by a rapid change in material properties - instead of full tracking. D.

Jacqmin has been exploring this possibility and has now developed a code capable of doing short time simulations

of relatively complex problems of both coalescence and breakup of drops. For long time simulations, the interlace

needs to be better preserved, and we are currently exploring ways to do that.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 1/92 EXPIRATION: 10/95

PROJECT IDENTIFICATION: 963-24-05-07

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Proceedings

Heyranni-Nobari, M.R.

Michigan, 1993.

"Numerical simulations of drop collisions and coalescence." Ph.D. thesis. The University of

Presentations

Nas, S. and Tryggvason. G.

Annual Meeting, 1993.

"Computational investigation of the thermal migration of bubbles and drops." ASME Winter

11-469
II. MSADProgramTasks-- Ground-based Research Discipline: Fluid Physics

Nonlinear Bubble Interactions in Acoustic Pressure Fields

PRINCIPALINVESTIGATOR:Prof. John Tsamopoulos State University of New York, Buffalo

CO-INVESTIGATORS:

Nasser Ashgriz State University of New York, Buffalo

TASK OBJECTIVE:

This project proposes both theoretical and experimental studies of the interactions between bubbles immersed in an

immiscible liquid. Specific objectives include:

1. To investigate the conditions when linearly accelerating motion of two interacting bubbles turn into a spiral

motion of one of them.

2. To study the delay and prevention of break up of accelerating bubbles.

3. To incorporate bubble velocity and fluid viscosity into a coalescence model.

4. To study the coalescence of two bubbles.

TASK DESCRIPTION:

The analytical study will locus on bubble oscillations and interactions of moderately large amplitude and will

determine conditions under which the axisymmetric flow turns into three-dimensional. For viscous liquids or large

deformation either the Boundary Element method or a combination of Finite Elements with the Volume of Fluid

method will be used. Bubbles will be suspended in an immiscible liquid using the acoustic levitation technique for

the experimental part of this project. Bubble motions and interactions will be induced by an additional acoustic

field. The bubble motions, shape oscillations, collision and breakup will be recorded with high-speed

cinematography.

TASK SIGNIFICANCE:

The results from this project will be beneficial to others in the bubble dynamics studies. It is well known that the

formation and collapse of cavities of gas inside a flow stream cause erosion in fluid-handling equipment. The effect

of a properly tuned acoustic field may help in the correct detection of submerged objects in the production of bubble

dispersions.

PROGRESSDURINGFY 1994:

During this reporting period, the tollowing have been accomplished:

1. A cylindric',d tank for the acoustic levitation of a single bubble has been designed, built, and tested.

2. A single air bubble has been successfully levitated in the levitation tank filled with water.

3. Shape and volume oscillations of a single bubble is being investigated using a high speed video camera with up

to 2000 frames per second.

4. Based on the experimental observations from the single bubble levitator, a new tank is designed which can

generate a relatively fiat pressure field in order to levitate two or more bubbles. This tank is being built at the

present time.

11--470
|I. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

1I_"I_l_o_"_o_"_|_g_i|_I"_u_"_t_|_"l_"_n_mmll_t_"_I_H_"_lIHi_l_"a_6_o_Dnol_Hi_IH_I_1_ "_"_I_"_1o_on_H_"_"i_q_"_"1_|_I_l_i_no_on_l_u_"_mH

5. A novel numeric',d technique for the simulation of the interacung bubbles in a viscous fluid is developed. This

technique is based on describing the liquid surliace by a spine function h(a,t), with a being the angle measured from

one axis at time t. After discretization, the spines H_(a_,t,) subdivide the liquid zone into conical subvolumes. The

volume of each of the subvolumes is updated using the local velocities at the interlace of every two neighboring

subvolumes. A technique is developed to calculate the new spines based on the updated subw)lumes. This method

implements Galerkin finite element method with penalty formulation.

6. The new numerical technique has been used to study the oscillation of a single drop and the interaction of two

liquid drops. Sample calculations are provided.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-24-05-99

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Mashayek, F. and Ashgriz, N.

Mashayek, F. and Ashgriz, N.

Mashayek, F. and Ashgriz, N.

interfaces.

Nonlinear instability of liquid jets with thermocapillarity. J. Fluid Mechanics, in press.

Advection of axisyrnmetric interface. Int. J. Numerical Methods in Fluids. in press.

A hybrid finite element - volume of fluid method for simulating free surface flows and

Int. J. Numerical Methods in Fluids, in press.

II________|____II___I_____________________I__I______________________________I__Ill____!__!_______Ill___n___________________I_IllI_II__Ill___________________ I IOOOOlOOOOOllllln IllUl OllllUaII IIIIIlllloaualloalllallllllllllIOllaonallnln IIIOlll OlllU
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

Residual Accelerations in a Microy, ravity Environment

PRINCIPALINVESTIGATOR:Prof. Jorge Vifials Florida State University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

This research program aims at developing a realistic theoretical model of the high frequency components of the

residual acceleration field (or g-jitter), and at studying ils effect on a variety of typical fluid experiments.

TASK DESCRIPTION:

The high-frequency components of the residual acceleration field are modeled as a stochastic or random process; that

is, a succession of random values of the intensity and orientation of the acceleration. Our research is divided into

two major parts, one analytic and the other numerical in character. In the lirst part, we formulate a hydrodynamic

problem that explicitly includes a random, time-dependent gravitational acceleration which is modeled as a narrow

band noise. In the second part, we develop numerical algorithms to simulate this type of random field and

incorporate them into Navier-Stokes equation solvers.

TASK SIGNIFICANCE:

All space experiments performed in the manned space environment are exposed to the high frequency components of

residual accelerations (g-jitter) on board the spacecraft. This effect can significantly alter experimental results. A

numerical approach is taken to determine what regimes of g-jitter will effect experiments conducted in a

microgravity environment. A generic class of problems is considered with emphasis on materials experiments.

PROGRESSDURINGFY 1994:

Buoyancy driven convection induced by a fluctuating acceleration field has been studied in a two dimensional square

cavity. This is a simplified model of fluid flow in a directional solidification cell subject to external accelerations,

such as those encountered in a typical microgravity environment (g-jitter). The effect of both determmistic and

stochastic gravity modulations normal to the initial density gradient are considered. In the latter case, we modeled

the acceleration field by narrow band noise defined by a characteristic frequency f2, a correlation time t, and an

intensity G z If the fluid is quiescent at t = 0 when the gravitational field is initiated, the ensemble average of the

vorticity at the center of the cavity remains zero for all times. The mean squared vorticity (_z), however, is seen

to exhibit two distinct regimes: For t << t, (_) oscillates in time with frequency fL For t >> t, (_z)

grows linearly in time with an amplitude equal to R_Pr/(1 + (_2t))z, where R and Pr are the Rayleigh and

Prandtl numbers of the fluid respectively. At yet later times, viscous dissipation at the walls of the cavity leads to

saturation, with (_) sat = (Prr¢ +I)R z.

(Pr_+l)a+_t _

A two dimensional model has been introduced to study the onset of parametric surface waves, their secondary

instabilities and the transition to spatiotemporal chaos. We obtain the stability boundary of a periodic standing

wave state above onset against Eckhaus, zig-zag and transverse amplitude modulations (TAM), as a function of the

control parameter e and the detuning from subharmonic resonance. We find that the Eckhaus and TAM stability

boundaries cross at a finite value of e, thus explaining the finite threshold for the TAM instability observed

experimentally. At larger values of e, a numerical solution of the model reveals the existence of a transition to

spatiotemporal chaotic states mediated by the TAM instability. Power spectra of temporal fluctuations in the

chaotic state are broadband, decaying as a power law of the frequency c0a with z = 4.0.

_!_!!_!_;_;_!_||_|_|_|_|_|_|_|_g_|_|_!_!_!;|!!_i!_!_!_!_|_|_|_|_|_|_;_|_|_|_|_||_|_!_|_|_;_;_|_|_|_|_|_|_|_

11472
II. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

i, o, o i i o n io i io nl o i i | i no i io i n i i i o i i o o i o| i a J i o a n i o o ! i o i a a o I Io I I o u I o o I a o I I o I I o| I o | I o a o o o o oo o I o I I o I a o 11 oo a o I o o o o o Io oi o i i o I i o o o o o oo o io o o I o n i o o a o o n Io o o a o o o o o I a * o i o o o i o o i o o| a o n i o o o o * i a o o o o o i im Ii o iii o o g o o o o _o o ii o I i o o i o o o o oo o o i i o n u | I I u I 11 o I I oo 11o I I o I a o I

Finally, we have started the analysis of g-jitter data gathered by the SAMS project during the SL-J Mission. Of

particular concern is the detection of deterministic and stochastic components, and a comparison of the latter with

the stochastic model of g-jitter currently used.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: O BS Degrees: 0

MS Students: 0 MS Degrees: 0

PhD Students: 2 F'hD Degrees: 1

TASKINITIATION: 6/91 EXPIRATION: 9/95

PROJECTIDENTIFICATION:962-24-05-36

NASA CONTRACTNO.:NAG3-1284

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Casademunt, J., Zhang, W., Vinals, J., and Sekerka, R.F.

J., Vol. 3l, 2027 (1993).

Stability of a fluid surface in a microgravity environment. AIAA

Chella, R. and Vinals, J. Order parameter representation for the motion of an active interface during mixing in cavity flow.

AIAA Journal, (preprintL

Gurtin. M.. Polignone, D. and Vinals, J. Two-phase binary fluids and immiscible fluids described by an order parameter. J.

Fluid Mech., (preprint).

Thomson, J.R., and Vinals, J. Statistical saturation of buoyant flow induced by a fluctuating acceleration. AIAA Journal,

(preprint).

Thomson, J.R., Casademunt, J., and Vinals, J. Cavity flow induced by a fluctuating acceleration field. Phys. Field, (in

press).

Zhang, W. and Vinals, J. Secondary instabilities and spatiotemporal chaos in parametric surface waves. Phys. Rev. Lett.,

(in press).

Zhang, W., Casamunt, J., and Vinals, J. Study of the parametric oscillator driven by narrow band noise to model the

response of a fluid surface to time-dependent accelerations. Phys. Fluids A., Vol. 5, 3147 (1993).

Proceedings

Thomson, J.R. and Vinals, J. "Cavity flow induced by an effective random gravitational field." Proceedings of the 32nd

Aerospace Sciences Meeting, Paper AIAA-94-0438, 1994.

Books

Casademunt, J. and Vinals, J. "Convection induced by a fluctuating acceleration field," in "Fluid Mechanics in

Microgravity." Edited by: D.A. Siginer, R.L. Thomson, and L.M. Trefethen ASME, New York, NY, pp 133. 1993.

Presentations

Vinals. J. "Residual accelerations in a microgravity environment." Second Microgravity Fluid Physics Conference,

Cleveland, OH, June 1994. NASA Conference Publication 3276.

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11473
Studies of the Dynamics of Charged Free Drops

PRINCIPAL INVESTIGATOR: Prof. Taylor O. Wang Vanderbilt University

CO-INVESTIGATORS:

C.P. Lee

A.V. Anilkumar

Vanderbilt University

Vanderbilt University

TASK OBJECTIVE:

The dynamic behavior of a charged liquid drop has been the subject of investigation. The basic assumption is that

the charge essentially reduces the surface tension of a neutral drop; hence the shapes and stabilities of a liquid drop

are greatly affected by the amount of charge presented on the drop surface. Various theories have been developed to

predict the dynamic responses of a drop under different charge conditions.

TASK DESCRIPTION:

One of the major technical problems facing "allcharged-drop experiments is the determination of charge quantity on

a liquid sample. To avoid the contamination and source loading problems, a noncontact charge-measuring technique

is preferred. From basic physics, there is only one way to determine the potential of a charged object by noncontact

means, and that is to measure the strength of the electrostatic field generated by the charge object. With precise

calibration based on the geometry of the system and measuring distance, the field strength can be used to obtain the

potential of the charged object.

TASK SIGNIFICANCE:

The study of the oscillation and rotational dynamics of charged liquid drops sustained by surface tension is

interesting from both a fundamental standpoint and a practical standpoint vis-a-vis processing materials in space.

The proposed ground-based experiments will help us to further the understanding of drop behavior and to optimize

the approved flight experiments.

PROGRESSDURINGFY1994:

Charged Drop Task

A charged-drop positioning device has been fabricated which 'allows charge measurement of the small volumes of

liquid which can be levitated on the ground. The average charge density is measured: the charge distribution is not

controlled. The final phase of this task has focused on studying the dynamics of charged drops undergoing

large-amplitude oscillations. High-speed imaging has been used to record the drops' behavior.

DPM Technical Support Task

The most recent and final work requested by the Drop Physics Module (DPM) Project has been to identity the cause

of the anomalous rotation observed in the DPM during USML-1. A flow-visualization system was built up to

study the flows inside acoustic chambers using both a DPM-like chamber as well as one with a simpler geometry;

The behavior of the smoke was analyzed with isolated acoustic signals, with the complicated mix of signals used

on USML-1, and with the USML-2 signals designed to control the tumble rotation.

A very long fiber was used to measure the actual torque on a spherical target in the acoustic chamber under the

conditions which caused flows in the earlier tests. Alter extensive searching a very limp fiber was found so that the

sample and fiber could be mounted on a fixture which could make similar torque measurements in the flight

chamber of the DPM. Measurements were made in that chamber while the DPM was at KSC as well as in the

chamber in the trainer at the Payload Crew Training Complex. The results of these tests are being analyzed and will

be documented in a final report by December 1994.

11-474
STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/91 EXPIRATION: 12/94

BS Students: 0 PROJECT IDENTIFICATION: 962-24-07-09

MS Students: 0 RESPONSIBLE CENTER: JPL

PhD Students: 2

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Grugel, R.N., Hightower. J., Hmelo. A.B., Wang, T.G. Use of mechanical deflection to eliminate metallic vapor

deposition on vacuum view ports. Review of Scientific Instruments, 65 (7), (1994).

Proceedings

Hmelo, A.B., Grugel, R.N., Wang, T.G. "Review of experimental facilities and reduced gravity platforms of containerless

experimentation." Proceedings of the TMS meeting, Denver. CO, 1993.

11-475
II. MSADProgramTasks -- Ground-based Research Discipline: Fluid Physics

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Experimental Study of the Vapor Bubble Thermosyphon

PRINCIPALINVESTIGATOR:Prof. Peter C. Wayner, Jr. Rensselaer Polytechnic Institute

CO-INVESTIGATORS:

Prof. J. Plawsky Rensselaer Polytechnic Institute

TASK OBJECTIVE:

The objective of this effort is to better understand the physics of evaporation and condensation as they affect the heat

transfer processes in a vapor bubble thermosyphon (VBT). In small systems, interfacial intennolecular forces can

be used to control fluid flow and heat transfer. The VBT, one such system, consists of a small enclosed container

partially filled with a liquid. When a temperature difference is applied to the ends of the VBT, evaporation occurs at

the hot end and condensation at the cold end -- resulting in a very effective heat transfer device.

TASK DESCRIPTION:

A transparent VBT will be designed and developed. The microscopic intermolecular three (pressure) field, which is a

function of the liquid thickness profile, will be measured using microcomputer enhanced video microscopy based on

interferometry. The temperature field will be measured using the interline absorbed film thickness and small

temperature sensors.

Models of the transport processes in the contact line region of a VBT which include the effects of liquid-solid and

liquid-vapor intermolecular torces have "already been developed. As part of this eftbrt these models will be further

retined and the transport characteristics of VBTs will be obtained by comparing the experimental data to numerical

solutions of the model.

TASK SIGNIFICANCE:

By studying liquid-fdm thicknesses and temperatures in VBT, a better understanding of the processes can be gained

that will lead to optimization of TBV designs.

PROGRESSDURINGFY 1994:

A preliminary experimental study of vapor bubble thermosyphons has been accomplished. In it measurements of

wall temperatures (using thea'mocouples) and liquid film thicknesses (using an image analyzing interferometer) were

made to characterize behavior of the VBT; valuable experience was gained in the operation of such systems,

Difficulties were encountered in finding a proper fluid and container material combination so that the system will

have desirable characteristics both optically and thermally. Proper procedures for filling the cells have been tbund to

be important in avoiding contamination. VBT cells for the main experiment have been designed and are currently

being constructed.

The experimental studies can be divided into a equilibrium and non equilibrium studies of the VBT. The

equilibrium studies have progressed to the point where we can make the following conclusions:

1. The use of an image analyzing interferometer, IAI, with a constrained vapor bubble thermosyphon, (CVBT), was

demonstrated under equilibrium conditions at lg.

2. Using the augmented Young-Laplace equation good agreement between the theoretical and experimental values of

the dispersion constant was obtained.

_1nin_n_nonnnu_Q_n_u_u_e_n_n_no_en_e_N_u_o_ene_e_ono_o_n_n_neno_e_o_o_oo_I_nu_ne_oononu_ee_II_ie_u_Dnn_n_n_n_ut_e_ent_I_u_n_oa_uju_o

11--476
3. A gravitational field restricts the range of lorces that can be studied because the curvature gradient, K', is a

function of gravity.

4. Ground based studies indicate that a flight experiment can be designed to ev_duate the augmented equilibrium

Young-Laplace equauon using the CVBT.

5. A flight experiment for fat le_Lst) a study of the augmented equilibrium Young-Laplace equation is warranted.

6. Ground based non equilibrium experiments are being developed.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 11/95

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-44

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 2

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

DasGupta, S., Plawsky, J.L., and Waynerjr. P.C. "Determination of the Hamaker Constant in an extended meniscus using

image processing." Abstract accepted for presentation at the 1994 annual meeting of A.I.Ch.E., San Francisco, CA. Nov.

13-18, 1994.

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11--477
Interactions Between Solidification and Compositional Convection in Alloys

PRINCIPALINVESTIGATOR:Prof. M. G. Worster Northwestern University

CO-INVESTIGATORS:

Prof. S.H. Davis Northwestern University

TASK OBJECTIVE:

The project aims to quantify the effects of convection on the structure and composition of cast "alloys. Particular

attention will be tocused on the form and influence of convective flows through the interstices of mushy layers

during solidification.

TASK DESCRIPTION:

Combined experimental and theoretical studies will be undertaken. The laboratory experiments will involve the

solidification of aqueous salt solutions, as representatives of general binary systems. The theoretical studies will

employ linear and nonlinear stability theory, asymptotic and numerical methods in the development and analysis of

predictive mathematical models.

TASK SIGNIFICANCE:

This study of fluid dynamics during solidification will aid the design of improved casting procedures (e.g., for the

manufacture of high-performance turbine blades). Additionally it will improve our understanding of air-sea

interactions in polar regions, where the formation of sea ice is a dominant contributor to the global heat budget,

leading to better climate modeling and prediction.

PROGRESSDURINGFY 1994:

Significant progress has been made with a study of the evolution of nonlinear perturbations to a growing mushy

layer. In addition to determining the stability of various finite-amplitude convective states, we have determined the

physical mechanisms that control the degree of subcriticality of the bifurcation's to convection within a mushy

layer. We have discovered a hitherto unsuspected oscillatory mode of instability in the mushy layer that is a

consequence of the intimate coupling between solidification and convection, and may cause compositional striations

to occur in a cast alloy.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

Phi) Students: 1

TASKINITIATION: 1/93 EXPIRATION:12/95

PROJECTIDENTIFICATION:962-24-05-63

NASA CONTRACT NO.:NAG3-1405

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONSFOR FY 1994:

Journals

Chiareli, A.O.P., Hupper, H.E., Worster, M.G.

139, 134-146 (1994).

Segration and flow during the solidification of alloys. J. Cryst. Growth.

Kerr, R.C. and Worster, M.G. The transient behavior of alloys solidified from below prior to the formation of chimneys.

Journal of Fluid Mechanics, 269, 23-44 (1994).

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11-478
Nucleation and Chiral Symmetry Breaking under Hydrodynamic Flows

PRINCIPALINVESTIGATOR:Dr. Xiao-lun Wu University of Pittsburgh

Co-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The aim of this research is to investigate nucleation and chiral symmetry breaking under shear flow. It has been

proposed that the symmetry breaking is a result of a strong first order phase transition coupled to a macroscopic,

velocity field. The process, often referred to as autocatalysis, is considered as one of the key steps for chemical and

biological evolutions. However, its very existence remains elusive.

TASK DESCRIPTION:

An individual molecule of sodium chlorate (NaC10:) is symmetric, but its crystal form shows distinctive optical

activity. If a solution of sodium chlorate is left undisturbed, hundreds of crystals slowly form as the solvent

evaporates, If these crystal are examined under crossed polarizers, one finds that half are left-handed and the other half

are right-handed. Equal percentage of the two species indicates that the energy barrier for the nucleation is the same

for the different handedness. It was discovered by Kondepudi et al. that under gentle stirring condition, the

crystallization seems to proceed in one direction, favoring either all crystals being right-handed or left-handed tbr

each individual experiment. The optical purity in each experiment is greater than 99%. However, if an ensemble of

experiments is carried out under the same conditions, one again finds an equal distribution of left and right-handed

species. This remarkable observation indicates that the system undergoes a transition from a totally symmetric state

to a totally asymmetric state simply by the introduction of a hydrodynamic flow.

The current experiments are designed to probe two important aspects of the above observations. (1) We would like

to know if the transition from the symmetric state to the asymmetric state is an abrupt transition or a smooth one,

as the flow parameters are varied. (2) To observe the existence of autocatalysis it will be useful to find correlations

between the local order parameter O=lnL-nRI/InL+nRI, averaging over some spatial scale I, and hydrodynamic flow

patterns in the system. Here nL and nR are the number densities of left and right handed crystals on the scale 1. Low

Reynolds number hydrodynamic convections, such as Tayior-Couette flow and Reyleigh-Benard convections provide

fertile testing grounds. In these hydrodynamic systems, the flow consists many local coherent structures, rolls and

eddies, and the convective mixing is most effective within these coherent structures.

TASK SIGNIFICANCE:

Effect of hydrodynamic convection on phase transitions is a significant problem not only for basic science but also

for technology. Microgravity provides a unique environment for which some of the above theoretical ideas can be

tested. Here minimization of sedimentation is crucial for both the experimental observations and for the theoretical

analysis. This study will enrich our general knowledge about nucleation and growth under hydrodynamic flow and

may be exploited to produce chirally pure materials.

PROGRESSDURING FY 1994:

To investigate the sharpness of the transition we have built a mixing apparatus which accommodates 20 samples at

a time. The flow in the samples is created by small magnetic stirring bars driven by horse-shoe magnets. To ensure

uniform flow for all the samples, the horse-shoe magnets are connected in tandem, driven by a DC motor. We have

incorporated a microscope and a video imaging system for counting the crystals when they grow to a fraction of a

millimeter in size. Our preliminary results suggest that the transition is rather smooth as the stirring frequency is

varied. The critical frequency fc appears to be around 2 Hz. For f<fc, the chiral symmetry is only partially broken,

whereas for f>fc, the symmetry breaking is almost a certainty (with probability greater than 90% for individual

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11479
runs). More recently we discovered that the critical frequency fc seems to depend on the volume of the solution used,

and possibly also depends on the location of the magnetic stirring bar. This new finding may be important in

differentiating the effects of hydrodynamic convection and mechanical "damage of incipient nucleus. It remains an

intrigumg possibility that both processes may be responsible for the chiral symmetry breaking transition.

To correlate nucleation events with the underlying hydrodynamic convection patterns, we have constructed an

electro-convection cell. The solution, containing 50% solid weight fraction of NaCIO3, is a weak electrolyte. When

a thin layer of NaCIO 3 solution is placed above an array of alternating magnets and driven by a DC current, the fluid

layer forms a set of vortices, which is commensurate with the arrangement of the magnets underneath the fluid. The

nucleation experiment under electro-convection is currently underway and its result will be reported elsewhere.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/93 EXPIRATION: 6/95

PROJECT IDENTIFICATION: 962-24-08-12

NASA CONTRACT NO.: NAGS-959

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Martin, B., and Wu, X.-L. "Nucleation and chiral symmetry breaking under controlled hydrodynamic flows." American

Physical Society March Meeting, Pittsburg, PA, 1994.

Wu, X.-L., Martin, B., and Tharrington, A. "Nucleation and chiral symmetry breaking under hydrodynamic flows." NASA

Microgravity Fluids Conference, Cleveland, OH, 1994.

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11-480
Oscillatory Thermocapillary Convection

PRINCIPALINVESTIGATOR:Prof. Abdellattah Zebib Rutgers University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The main objective of this work is to investigate the influence of free-surface deflection on the onset of oscillatory

thermocapillary convection in microgravity. The study is to investigate the flow instability of thermocapillary

flow. The Hopf bifurcation will be studied using a numerical method with the consideration of free-surface

deflection. In addition, the disappearance of the Hopf bifurcation will be investigated.

TASK DESCRIPTION:

In the domain perturbation approach (valid tbr small capillary numbers (Ca---K))), time-dependent, two-dimensional

combined buoyant thermocapillary motions in a rectangular cavity are computed using a second-order accurate

finite-volume method. Two situations are investigated: The O(1) pure buoyant convection (with the Marangoni

number Ma=0) is known to exhibit a Hopf bifurcation at some critical value of the Grashof number, Gr,. Thus, by

studying the combined thermocapillary-buoyant convection for values of

(Ma, Gr) near (0, Grc,)

we seek to determine the stability boundary for onset of oscillatory motion and its nature in the limit of vanishing

buoyancy, Gr=0. Both positive and negative values of Ma are considered. In the second problem we consider pure

thermocapillary driven convection (Gr=-0). The solution to the zeroth order system is known to be stationary.

Higher order effects are unknown and will be investigated.

TASK SIGNIFICANCE:

These studies can contribute to our fundamental understanding and potential control of thermocapillary instabilities.

Detailed information of thermocapillary flows can be obtained through this comprehensive numerical study.

Mechanisms for controlling the flows will be identified. Thus the fluid management and heat transfer processes

will be better controlled in space.

PROGRESSDURING FY 1994:

For low Prandd number fluids, the solution to the zeroth order system is known to be stationary at parameter values

of interest in semiconductor crystal growth. We have established that incorporating higher order terms also leads to

steady thermocapillary motions. This important result is both in agreement and disagreement with recently

published papers by other researchers employing different computational methods. Results from current study

showed that there exists a critical Rayleigh number below which no flow oscillations could occur. Different

conclusions were drawn from other researchers in the studies of similar configurations.

STUDENTSFUNDEDUNDER RESEARCH: TASK INITIATION: 2/93 EXPIRATION: 2/96

BS Students: 0 PROJECT IDENTIFICATION: 962-24-05-49

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

11--481
[I. MSAD Program Tasks -- Ground-based Research Discipline: Fluid Physics

.lllll"l"tl*llillllllo*ll|llHllol"tloll0tl*ll* JI*II|IlOnI*IIIla*IIOIlUOlUlIIlilI"I00 H O H otl*llonl*liaomiJollll*lltllonl*aloollHl"louooola*_uolllil_ol|ol|ol"l|*ll|llut .llHl.lootoo J l*ll|lllll.aullilool|lloelHIn*nJoo_a| Jnlutol

,Iournais

Mundrane. M. and Zebib. A.

Fluids. in press.

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Steady and oscillatory, two-dimensional buoyant thermocapillary convection. Physics of

Mundrane. M. and Zebib, A. Oscillatory, two-dimensional buoyant thermocapillary convection. Physics of Fluids, in

press.

Mundrane. M., Xu, J., and Zebib, A. Thermocapillary convection in a rectangular cavity with a deformable interface.

Advances in Space Research, in press.

Presentations

Muncrane, M. and Zebib. A. "Oscillatory thermocapillary convection." Second Microgravity Fluid Physics Conference.

Cleveland, OH, June. 1994.

Mundrane, M. and Zebib. A. "Oscillatory. two-dimensional buoyant thermocapillary convection." ASME-WAM, New

Orleans. LA, November. 1993.

Mundrane. M. and Zebib. A. "Marangoni convection with a deformable interface." ASME-IMECE, Chicago, IL,

November. 1994.

Mundrane. M., Xu, J., and Zebib, A. "Thermocapillary convection in a rectangular cavity with a deformable interface."

COSPAR '94-G1-Symposium, Hamburg, German. July 12-16, 1994.

Zebib, A. "Buoyant thermocapillary convection." presented at the University of Arizona, May, 1994.

! i nuooI le ! iooooonni nu| | o| oo* on i ooi olo aloi ooool aooo| oo| i1 | ooo! | ! ao| aI i u* i a| oi no uouo! i onaonoe ouoi onooon* o| oI ooI | Iumun* n! | noeoo oIn I I ! oI ooI o! oo! *o oooI oil o inn I ! ono| ena et! I ooooaI o! | og! l lO ill l I anI oo oooOl I el I * niena e II Ol aOI oo l lOll OOI Oil Oil O01eoo ooo in onl ol

11-482
Synthesis and Characterization qf Single Macromolecules: Mechanistic Studies of Crystallization

and Aggregation

PRINCIPALINVESTIGATOR:Prof. Spiro D. Alexandratos University of Tennessee

CO-INVESTIGATORS:

K. Cook

D. Joy

P. Phillips

B. Wunderlich

University of Tennessee

University of Tennessee

University of Tennessee

University of Tennessee

TASK OBJECTIVE:

The principal objective is to prepare single-molecule polymer amorphous particles and crystals by thermally induced

precipitation / crystallization from bulk dilute solutions and by precipitation / crystallization via solvent

evaporation from electrosprayed nanodroplets of dilute solutions. Polymer-polymer interactions will be controlled

in order compare the effects of interchain and intrachain entanglements on the chemical and physical properties of a

polymer particle or crystal. Successtul preliminary studies will be extended to studies in microgravity which will

'allow for a much more sensitive probing of intermolecular interactions through differences in properties of the

polymers.

TASK DESCRIPTION:

An electrospray attachment will be constructed for a conventional mass spectrometer, allowing for individual

polymer chains to be isolated as they emerge from the instrument. Gravity complicates their isolation but its effect

could be minimized with very dilute solutions. The morphology of the single chains will be characterized by high

resolution low voltage scanning electron microscopy. Backscattered electron imaging will also be utilized, with

spatial resolution of 1-3 nm. Thermal analysis will reveal details of chain motion, including details of

crystallization kinetics and the effects of inter- and intrachain entanglement.

TASK SIGNIFICANCE:

The commercial and technological importance of plastics cannot be overstated. Specially designed plastics have

been applied as materials in aerospace construcuon, medical prosthetics, and organic semiconductors. This wide

range of applicauons stems trom the wide diversity of chemical and physical properties of the macromolecules (i,e.,

polymers) which serve as the building blocks of the plastics we encounter. While our understanding of the origins

of this diversity has advanced in recent years, it remains tar from perfect. With the increasing importance of

composite materials, the gap between theory and experiment may even be widening. An investigation into the role

of the interactions between discrete macromolecules on the final observed macroproperties requires the availability

of samples of controlled molecularity (i.e., one, two, three .... macromolecules). It is the goal of this research to

prepare and characterize samples comprised of single polymer molecules of known molecular weight, then compare

the observed properties with those of comparably well-controlled systems where the number of interacting

macromolecules is known. This will allow lor the design of new plastics with targeted properties including

strength, durability, and biodegradability.

PROGRESSDURING FY 1994:

This research had September 1, 1994 as its official beginning. We have defined a series of experiments and have

identified a post-doctoral research associate who will be responsible for carrying out the experiments. The

post-doctoral associate has recently accepted our offer. Laboratory space has been identified and the necessary

supplies are being purchased.

il--483
STUDENTS FUNDED UNDER RESEARCH: TASKINITIATION: 6/94 EXPIRATION: 6/96

PROJECTIDENTIFICATION:962-21-08-25

NASA CONTRACTNO.:NAGS-1065

RESPONSIBLECENTER: MSFC

i! e! e| | I eI |o iel o| I eeel |ll |e! ell ;l! eel | leo el | le| lee lu oil; I | |1 ! ei i | i ! | ii ei | | i i e! el lee ell ill eIH| |ll le | ill Ill lie I | I ;1! e|! ;1_ |lea Ill |e I eI oe |11 | I | | I el | | ! eI i e|| I |ll I I | III !eI |I | | I | Ill OI | _11| I ! e| ! I l| | le | oI | i | | I | |II | I ! Ill Ill |I I Ill | I I Ill |I I II I I I e| I oI II

I1--484
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

I I*;lll*lllllltllllllMiilllllll.lllllel; Jlilt I_I_Il;t|_I_u_I"_"_oH*l_ii_*"_I_|_|ii_I_jt_Il_iIIIl"l_II_1_I_u_m_ji_I_aII_!i_l*_o_iI|i_i_|_;*_t_*_I_iI|_It_I_j_Il_iI_aa|_j_ J llll**l*ulloll*lll**llll*llo*rl

,4 Novel Electrochemical Method for Flow Visualization

PRINCIPALINVESTIGATOR: Dr. T. J. Anderson University of Florida

CO-INVESTIGATORS:

R. Narayanan

A. Fripp

University of Florida

NASA Langley Research Center (LaRC)

TASK OBJECTIVE:

The objective of this research program is to develop and demonstrate a novel electrochemical technique to visualize

the dynamic states in high temperature liquid metals. This technique uses the oxygen anion-conducting ceramic

electrolyte yttna stabilized zirconia in a crucible material which holds the model liquid metal tin in a Bridgman

configuration. Electrochemical ceils will be constructed at various positions 'along the side wall and bottom of the

solid electrolyte. The !x)ttom cell will operate in the electrolytic mode to establish a well detined boun "dary

condition with respect to the titrated oxygen tracer concentration. The side wall cells will be operated in the

galvanic mode to measure the dynamic oxygen concentration at the various wall IocaUons. Well defined convective

flow patterns will be established for this model geometry and the resulks will be compared to numerical predictions

of the flow patterns. In this manner the sensitivity of the technique will be determined.

TASK DESCRIPTION:

In order to identify the sensitivity of the technique, a cylindrical crucible with local electrochemical cells at 5

vertical and 4 azimuthal positions (20 total cells) will be constructed. A thin (1/8") alumina rod will be rotated in

the melt along the central axis in an isothermal furnace to produce a well defined dynamic state. At suitable

rotation speed and aspect ratio, Taylor vortices are expected and the oxygen concentration variation along the side

wall will be measured alter establishing a zero concen_'ation boundary condition at the bottom lace of the melt

cylinder. Next, the flow directions of dynamic states (oscillatory flow) developed in a Sn melt without the rod in a

destabilizing vertical temperature gradient will be studied. In this experiment, a single cell will be

electrochemically pulsed and the time response monitored at the other cells. The experiment will be repeated with

different electrolytic cells and pulsing experiments will also be performed to identify the natural oscillation

frequency. In a final series of experiments, the continuous response of the sensor cells will be measured to a step

change in boundary condition. The results will be compared to a complete 3 D calculation of buoyancy driven

flow accounting for sidewall conduction and radial transport.

TASK SIGNIFICANCE:

In the processing of many advanced materials, for example the bulk crystal growth of semiconductors, the fluid flow

state of the liquid determines the quality of the material produced. Although flows in the liquid are not intentionally

created, natural forces produce flows. Since the melt is often at high temperature, exhibits a high vapor pressure,

and is not transparent, it is extremely difficult to see the fluid flow pattern. Thus, we must rely on the results of

calculations which have drawbaclcs. We have proposed a novel method to measure flow patterns in liquid metals by

using solid state electrochemical sensors to measure the time variation of a tracer species. In a microgravity

environment, it is anticipated that the magnitude of natural fluid flow will be greatly reduced and produce improved

materials. In order to correlate material properties to the fluid flow pattern, we must know the pattern. This

technique promises to provide such insight. Potentially, the method could be adapted for improved process control

and manu facturability.

PROGRESSDURINGFY 1994:

This project has been active for 4 months. In this time, the furnace system, gas purification manifold and

electrochemical measurement equipment have been established. An alumina based crucible system will be necessary

to avoid wall transport of the oxygen tracer. A design of the crucible has been developed which incorporates tapered

11-485
yttria(YSZ) stabilized zirconia plugs located 'along the s/dew'all and a YSZ disc at the bottom. Work is in progress

to incorporate computer based data acquisition. In addition, 3 D modeling efforts of the Bridgman geometry have

been initiated. A student has been recruited from the Fall entering class and a post doc with experience with solid

electrolytes will join the program m November.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 7/96

BS Students: 2 BS Degrees: 1 PROJECT IDENTIFICATION: 962-21-08-26

MS Students: 0 MS Degrees: 0 NASA CONTRACTNO.: NCC8-51

PhD Students: 0 PhD Degrees: 0 RESPONSIBLECENTER: MSFC

I I ! Ill I OI I Olllll III I I I II I Ill Ill Ill n 1el i ell ill ell II Ii ol l oi l I i l oi I i l l I I i ol ill Iii OllOlll lee ill n l ii lii l i i i ii i ill ello I llll iii i ii i nil oi i Ii lin I ! II ! in I I I Oil I I oI nnI nI oIl eIiI I I! I I I ni ill meooI I|11 Ill nl II oI I I I I oI $111 Illll I i i II I II I Ill ii l ool lI onII I ii nl! iI I I

11--486
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

_jl"i_|I_i_u"_l_i_|_I_iIl_aI_ii_iii|I_tI|Ii_l_I_|_¢_iHiHiDi_jj_";_i_ I.ll,,10,I.II,Ha,,.m,.,I.l,,I.,J.l,.,.,IHll.l.,¢ll.l,|l,¢,l,,l|l,n,u H,II.,,_,l,,l.|,_lll0Hnll_,l.,eH_l,_l.l.,._.t.l_

Foam Metallic Glasses

PRINCIPALINVESTIGATOR: Prof. Robert E. Apfel Yale University

CO-INVESTIGATORS:

N. Qiu Yale University

C. Boa-Teh Yale University

TASK OBJECTIVE:

The scientific objective is to determine the parameter space for which foamed glasses are possible. The engineering

objectives are to design apparatus to operate in this parameter space and to investigate the practicality and

desirability of this process for satisfying technological needs and for producing new opportunities for the application

of these materials.

TASK DESCRIPTION:

Amorphous materi',ds are an important cla._s of materials because of their many unique features, such as the absence

of crystal defects (e.g. grain boun 'daries or dislocations) and a wide compositional range over which a single-phase

amorphous material can be tormed. A novel processing approach and experimental design to achieve as-cast bulk

amorphous materials are investigated, since a bulk form of amorphous material is required in many applications.

By sudden decompression of a melt that is seeded with a volaule liquid, the dispersed "foaming" liquid vaporizes,

taking its latent heat of vaporization from the melt, thereby homogeneously cooling the melt. Due to a high

decompression rate, a sufficient cooling rate may be produced to yield an amorphous solid loam.

The experimental program is divided into three major sections: proof of foaming principle with organic materials;

tests with the water-tin system, even though it is known that such systems will not form a glass; and tests of an

alloy system for forming a foamed metallic glass. The first of these is to verify our expectations with regard to the

foaming process and the production of a bulk foam. The second is to give us experience with a metallic system

that others have worked with and which may present behaviors unique to metals and not observed with organic

materials. The third step is obviously an important milestone toward foamed metallic glasses. The expertmental

program will be complemented by a theoretic'd/computational study of this highly transient 'Toaming" process and

by comprehensive materials analysis of all product specimens.

TASK SIGNIFICANCE:

Rapid decompression of seeded melts is a novel processing approach to produce loam metallic glass which is an

open solid bulk structure that may have glass properties and low density. These loam metallic glass materials

should possess few structural detects and may have many potential applications, such as lightweight and high

strength structural materials, or matrix materials that can be filled with other materials to suit some special

requirements.

PRO6RESSDURJN6FY 1994:

Preliminary results have shown that this novel method for solid foam processing is feasible. Foam p-terphenyl has

been produced by sudden pressure decompression of melted p-terphenyl in which water is dispersed. The foam is an

open, porous and yet interconnected structure, and can been made with a density as low as 12% of the original

density of p-terphenyl. High water to p-terphenyl ratio and high releasing pressure help produce foam with high

porosity or low density.

Limited expertments of foam processing of metal tin, using the same apparatus for p-terphenyl, and water as the

foaming agent, were performed. Within the conducted experimental regime, no massive loam was observed and the

resulting tin was not an open structure. However, in some surface areas, holes and convex hills and dimples were

observed. Some features are similar to those of loam p-terphenyl. The differences of surface tension and density

II-487
lI. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

i o i |i a o o ! | | i i t I I o o I oo ! Io | I m| I o o ! o o _I | oI o | I o ! I J o i a o | a o ! ta a n a o | ! o o ii o i oo I ao n a i | I o | a o o I oo i! o t o o i * u; oi a iiI o I a o o o o o ii u i n o o | a J I i o a oo i ! o i u lu u o i i ! Ii a o | oo o Io a n a i n a i | a o oI a o o o o I i * I a o o i a oI o o o a o o I o e I o t I* I o o _ o I u a I u| _ _ ! _ ! a | I ! o i| |g _ o I I o n u a | _ | | nI D |! J i n u u o | DI 0 * I

between tin and water are large. Tin and water tend to separate rather than mix together even at elevated temperature.

Construction of a more sophisticated apparatus is currently in progress in order to disperse water uniformly into tin

to improve the chances of producing loam tin. In addition to the experimental progress, the initial formulation of

theoretical/computational study of this highly transient "foaming" process has been made.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 3/93 EXPIRATION: 3/96

PROJECT IDENTIFICATION: 962-25-08-24

NASA CONTRACT No.: NAG8-947

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Apfel, R.E., and Qiu, N. "Foam metallic glass." Proceedings of the NASA Microgravity Materials Science Conference,

Huntsville, AL, 129 (1994).

no! ! ooonl _oeoooi i oi ueoi i i e! II ! ! ! ! Ii ae! aD| I ! I! ! JUI ! I ! I ee! 01 O! ! ! ei i i i ooI ! II o! I ooI i | ! u! l ! !o! ! l I ol a| IoI I! o*g $I I eI ae |I ! I I! Ill | oI I oooli $| Io ! I IlIDI ! I II I I * ! a! I I ! ! | ! ! oo|o o|1 o|o o! oIe! ooDOeIll! l eI II ! I I I I c n! oii ei i i i aeii ei il I! eooel OeO e !I eI I ! I | I I 4O! O! all |D O

11488
Nucleation and Cluster Formation in Levitated Droplets

PRINCIPALINVESTIGATOR:Prof. Stephen Arnold Polytechnic University, New York

CO-INVESTIGATORS:

A.F. lzmailo

A.S. Myerson

Polytechnic University, New York

Polytechnic University, New York

TASK OBJECTIVE:

1. Employment and improvement of the existing experimental Electrodynamic Levitator Trap (ELT) technique in

order to investigate stochastic motion of the ELT confined microdroplets of supersaturated solutions in the case

where the dimensionless drag a and driving b parameters are much greater than one:

2. Development of an appropriate theoretical formalism to describe stochastic motion of the ELT confined

microdroplets of supersaturated solutions in an atmosphere near the Standard Temperature and Pressure for the case

where the dimensionless drag a and driving b parameters are not necessarily small (less than oneJ.

TASK DESCRIPTION:

Components of this research include:

1. Experimental study of stochastic motion of the confined levitated microdroplets of various supersaturated

solutions. The containerless levitation "allows to considerably delay nucleation onset and, thus, provides an unique

method to study the formation and evolution of subcritical solute clusters. This study includes measurement of

such time-dependent microparticle characteristics as the standard deviation of its confined stochastic motion, activity

of the solute dissolved, etc.. Since the measured characteristics are extremely sensitive to the appearance of

subcritical solute clusters (solid inclusions) inside of the studied microdroplet the proposed experiment provides an

unique opportunity to study metastable state of matter.

2. Development of theoretical models of the microparticle confined stochastic motion for the two principally

different causes: (1) when there are no solid inclusions inside, i.e., when the microdroplet solution is undersaturated,

and (2) when there are solid inclusions inside of the microparticle, i.e., when the microdroplet solution is

supersaturated. These two models will be developed for the particular case where energy dissipation of the

microdroplet motion in the levitator atmosphere is linear.

TASK SIGNIFICANCE:

Understanding of the metastable state evolution in supersaturated solutions is of extreme importance in the problem

of governed nucleation and crystal growth. Since this evolution consists of the birth-death process of subcritical

solute clusters, we outline the lollowing significance:

1. It is a challenging expertmental problem to study metastability since any heterogeneity may cause instantaneous

nucleation lollowed by crystallization. Therefore, development of the containerless (without heterogeneities due to

container walls) experimental technique is of interest.

2. Analytical description of stochastic motion of the confined supersaturated solution microdroplet will 'allow

treatment of the obtmned experimental data.

PROGRESSDURING FY 1994:

We have performed experiments with microdroplets of various electrolyte and non-electrolyte supersaturated

solutions. The obtained experimental results and their theoretical treaunent for the case of electrolyte supersaturated

11-489
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

solutions have 'allowed to make some interesting conclusions concerning distribution of subcritical solute clusters.

It appears that there is such a particular solute supersaturation concentration when solution electrical conductivity

becomes equal to zero, i.e., all solute ions dissolved become associated into elecmcally neutral Bejrrum pairs.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-25-08-30

NASA CONTRACT NO.:NAG8-1060

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Izmailov. A.F.. Arnold, S.. and Myerson. A.S. Parametrically driven microparticle in the presence of a stationary

zero-mean stochastic source: model for thermal equilibrium in the Paul trap. Phys. Rev. E. vol. 50. 702 (1994).

l I II III lilll IS I I l II I I lie III III I ii III IiI I I III I II I el l I I l I IS mIl mis i i I ii l ii i i i i i i i l i l l i i i l il i i i l i i ii i l ii l ii i l I l i i i l i i i ii l ii l ii i iii i ii it i is i l ill i i i i i i ii i i i i i i i i i i ii i is i i i i i I i ii i l ii l ii I i i I iii Ill I I I I11 II I I II l I1 eiii i i I I tO Ill Ill Ill I IIll III III I II I II I I I I I

11--490
Microwave Materials Processing in Microgravity

PRINCIPALINVESTIGATOR: Dr. Martin B. Barma[z Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The Microwave Materials Processing in Microgravity task objective is to apply the unique capabilities of

microwave heating and positioning to process materials in microgravity. The task objectives will include 1)

determination of the reaction mechanism, microstructure development and physical properties associated with

microwave synthesis of ceramics, 2) development and application of microwave techniques for (a) monitoring the

energy absorption during processing and (b) measuring thermophysical properties of materials in microgravity, and

3) theoretical modeling of unique microwave heating and positioning capabilities in a microgravity environment.

TASK DESCRIPTION:

There is a recognized need to produce advanced refractory ceramics that have higher melting temperatures aud

improved mechanical properties (such as strength and toughness). In recent years, ground-based experunents using

microwave heating have demonstrated enhanced rotes of sintering of ceramic materials leading to new

microstructures. The synthesis of ceramics in a microgravity environment could provide the opportunity to produce

contamination tree ceramics with controlled microstructures that lead to advanced structural applications.

Microwave processing can heat many glass and ceramic compositions veo' rapidly to high temperatures, it can heat

them more uniformly than other methods, and it is energy efficient. Of particular interest is the application of

microwave to the combustion synthesis process. Other important potential applications are crystal growth, and

fiber pulling in space. Microwaves can generate a well defined temperature gradient within a material leading to the

possibility of melting only the interior of a cylindrical sample, or leading to a radial gradient of the index of

retraction upon solidification. By appropriate monitoring of the microwave parameters during processing one can

'also measure various sample properties as well as obtain energy absorption information which can be used to

characterize the sample reaction and densification mechanisms. Microwaves can also produce unique positioning

forces.

TASK SIGNIFICANCE"

This task may lead to a new novel technique for the efficient processing of high temperature ceramics in a

microgravity environment. The ability to microwave heat and position a sample may also lead to a new

containerless technology that is ideally suited Ior controlled processing of materials in microgravity.

PROGRESSDURING FY 1994:

During the last year, we have (a) developed a new plasma enhanced microwave joining technique. This method was

used to join 99.8% pure alumina rocks at 2000 C, (b) successfully demonstrated microwave annealing of Cu thin

films on silicon substrates to eliminate the voids present in sub-micron size interconnects. This new technique

could support the development of ultra large-scale integrated (ULSI) semiconductor circuits, and (c) demonstrated

microwave ignition of the combustion synthesis process to produce dense high strength TiC.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 10/81 EXPIRATION: 9/94

PROJECT IDENTIFICATION: 962-25-04-07

RESPONSIBLE CENTER: JPL

II--4 91
II. MSAD Program Tasks-- Ground-based Research Discipline: Materials Science

i: n l _ o I a I ia in i o i _ J o i ill Io | i| o o o | i a o i i o |a o ii o o I | ! o a i I I * ! Io oI o o _ a o i i o i a o i Io Ii o I ¢ g ! I a o i i o i io i i o I n o I J | Io o | g i i I o I i o |! o !I o |a o ! i i o | i i i I o o I_ o n I o o J a o I I o g i o o I I o |o a o i n _ I I o I I o o I o o I Io | i o ! I ! I i | o I lln g o i i o i | o I a oI I I I o o I o o I a oI a ! o I o I o o I o I !o o Io I Io ! I o o o| u I o la o I i | !

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

,Journals

Jackson. H.W, Barmatz. M., and Wagner, P.

Transactions. 36, 189 (1993).

Transient temperature behavior of a sphere heated by microwaves. Ceramic

Proceedings

Brain. R.A.. H. A. Atwater. and M. Barmatz. "Rapid selective annealing of Cu thin films on Si using microwaves." MRS

Spring Syposium Proceedings, 1994.

oaoeo! Ilu no! II! | |uo I I I eo! oI! olie ! og ! !! ! ! !llO! II! ol!olll ! I! I o!nI ! I Io I oo I oil!l! ! olUll! l!l !1! o!!Ill!hi! !llOl oo!llO! I!! |!1 |!1 |el !In |!!||1| |o ! I!!ln!l$ uo ! o! I Ion! | I o! I I I |ol o|!o !1! I o! I ou!!! !! I !1 !hi! ! $uo oI aI I!Oll I mt ! OI !$ I! $I ! elu | na | |a In ! II ! !1! |o I oouu! u!o I II I Io ! !o

11492

i
Studies of Containerless Processing of Selected Alloys

PRINCIPALINVESTIGATOR:Prof. Robert J. Bayuzick Vanderbilt University

CO-INVESTIGATORS:

W. Hofmeister

M. Robinson

Vanderbilt University

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The research focuses on determining the speed of solidification as a function of undercooling in the large

undercooling regime.

TASK DESCRIPTION:

The work involves the undercooling of refractory metals and "alloys by contamerless processing. In particular,

experiments are done by use of electromagnetic levitation (on the bench) at Vanderbilt University. Specifics

addressed are maximum undercoolings m refractory metals and "alloys, nucleation frequency in reli'actory metals and

alloys, the effect of undercooling on solidification velocity in refractory metals and alloys, and microstructural

development in refractory metals and alloys as a tunction of deep uudercooling/solidification velocity and rapid heat

removal.

This work consists of a comprehensive investigation on growth of the solid from the undercooled liquid in selected

metals and alloys. In order to do this, containerless processing is essential not only to eliminate the effect of the

container on nucleation but 'also because the "alloys of interest are highly reactive and become contaminated with

crucible material.

The ground-based technique for containerless processing applied to this effort is electromagnetic levitation ion the

benchi at Vanderbilt University.

The alloys studied are TiAI based. In addition, studies are done on pure Ti and pure Ni, as points of reference and

because of their stand "alone contribution to science. The particular alloys are chosen because they exhibit a wide

solubility range as seen in the phase diagram and, within compositions ranges, exhibit a tendency to be

tmencumbered by competition between alternate phase selection in the deep undercooling regtme.

The "alloys as well as pure Ti and Ni are studied in order to determine the solidification velocity as a function of

melt undercooling. The velocity is determined using ultra high speed imaging to track the solidification front as it

moves through the specimen. In opaque samples this can be done by monitoring the movement of the thermal field

developed by recalescence. An instrument has been developed that consists of a 10 by 10 array of parallel tapped

photodiodes and data acquisition. The system is capable of capturing data at rates of up to 1 million frames per

second and the output from the array is calibrated for conversion to temperature. For this alloy and each pure

element, a plot of the solidification velocity as a function of undercooling is developed. Of particular interest are

the mechanisms controlling the rate of solidification at various undercoolings.

TASK SIGNIFICANCE:

This research is of interest not only because of its contribution to solidfication theory but also because of its

relevance to the development of useful high temperture alloys. In order to understand the mechanical properties of

these high-temperature materials the microstructure of the material must be understood. This requires an

understanding of all of the factors that contribute to the genesis of the microstructure. In particular, the velocity

with which the solid grows into the liquid is pertinent.

i i i ii i n n I i n ! n i n ni ! n i i i i i ! i t n ii i i i ! i i i I i n ii n i i ill i n i i I i i nii i I i i i i ii i i i n i in i ii i i i i i i i ii i i Ii ii i i ni ! i I I II i nnn I I I I i i i ii i I I I I | ! I | I I| i I! i In | I i I ! i i nin n ii I I I I I lil in i i nnnnn i i i i n n nii ii i ii I ii i i ii n i ! I I I i i i ni i i I n ! n i i ! i i i n i ii ! n i ! n n i ill ! i i i i i ! i i n i i ! ii ! n| ! i ill i

I1--493
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

!_I_!!_|_!g_!_|_|_!_!_!_|_i_!_*_|_|!_|||_|_|_!_*_!_!_|Q_t _|_!_!_|!_!_|_t_l_|_|_|_|_!_|!_|_|_|_!_|_g_!_1_1_

From a purely scientific stand point the relationship of the solidification velocity to the melt undercooling is not

well understood. The data reported by various scientists conflict with each other and are not in good agreement with

solidification theory. It is, theretore, necessary, to built a quantitative experimental data base that can be compared

to theory, and ",allow the areas of discrepancy to be addressed.

PROGRESSDURINGFY 1994:

The measurement of the solidification velocity of undercooled liquids has continued with the development of an ultra

high speed imaging system. The system consists of a parallel tapped ten by ten array of photodiodes, amplification

stages and data acquisition. The system captures data at rates ranging from 500 to 1,000,000 frames per second and

the output is calibrated tor temperature measurement.

The solidification velocity of Ti-60a/o AI was measured using the ultra high speed imaging system. Equilibrium

solidification of Ti-60a/o Al produces the ordered intermetallic gamma phase with the L 10 structure. Theory

predicts that this alloy will solidify in the ordered phase at low undercoolings. As the melt undercooling prior to

solidification increases theory predicts that the alloy undergoes a transition to solidification of a disordered FCC

phase. The experimental results of this study for the solidification velocity as a function of undercooling indicate

three regimes in the solidification behavior. First, at low undercoolings, the alloy solidifies in the ordered phase.

Second. at intermediate undercoolings, the solidification is undergoes a transition from solidification of the ordered

phase to solidification of the disordered phase. Third, at high undercoolings, the alloy solidifies as a disordered FCC

phase.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 2/89 EXPIRATION: 8/94

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-25-08-20

MS Students: 0 MS Degrees: 0 NASA CONTRACT NO.: NAG8-765

PhD Students: 1 PhD Degrees: 1 RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Bassler, B.T.. Hofmeister, W.H., Carro, G., and Bayuzick, R.J. The velocity of solidification of hightly undercoolded

nickel. Metallurgical and Materials Transactions A. vol. 25A, 1301-1308 (1994).

Presentations

Bassler, B.T., Hofmeister. W.H., and Bayuzick. R.J. "Investigation of solidification velocity and microstructural genesis

as functions of undercooling for gamma titanium aluminum." 3rd International Conference on High-Temperature

Intermetallics, San Diego, CA, May 16-19, 1994.

Bassler. B.T., Hofmeister, W.H., and Bayuzick, R.J. "Ultra high speed imaging of electromagnetically leviated metals."

12th Symposium on Thermophysical Properties, Boulder, CO, June 19-24, 1994.

I It IaI I I I I I I l I I I I I I I II I I I t I I l I i aII l II I I I l I I I l II I IaI I l I I l I II | I I I I t I I I I I aI I I I I I l I t I I aI I II I Ili l I I I I I I II I l I 11 t | I t I I I| _| I I I | aI I I I I I II I I I I t I ! I I t I I I II I I I I I I 11 at I I I |I I I i i i I i i i i i Ii ii i i i i i i i i i I i i ii i Ii i i i i i i i i i i ii i it i i i i I i i i 111t i i t aI I I i ii I i i i i I i i i ii iI i I i i

I1-494

r
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

Studies of Nucleation and Growth of lntermetallic Compounds

PRINCIPALINVESTIGATOR:Prof. Robert J. Bayuzick Vanderbilt University

CO-INVESTIGATORS:

W. Hofmeister Vanderbilt University

TASK OBJECTIVE:

The objective of this research is to quantitatively define the nucleation behavior of selected intermetallic compounds

and the relationship between degree of undercooling and the speed of growth of the solid.

TASK DESCRIPTION:

This work focuses on the undercooling of intermetallic compounds and their pure metal constituents by

contmnerless processing. This ground based research involves a continuation of already established drop tube work

and electromagnetic levitation (on the bench). Specifics to be addressed are maximum undercoolings, nucleation

frequency, the effect of undercooling on solidification velocity in refractory metals and alloys, and microstructural

development as a function of deep undercooling/solidification velocity.

Re.search Approach

This work will consist of a comprehensive investigation on nucleation and growth of the solid from the undercooled

liquid of selected intermetallics and their pure metal constituents. In order to do this, containerless processing is

essential not only to eliminate the effect of the container on nucleation but also because the metals and alloys of

interest are highly reactive and become contaminated with crucible material.

Three ground-based techniques lor containerless processing will be applied to the effort. These are flee fall in the

long drop tube at the Marshall Space Flight Center, electromagnetic levitation ion the bench/at Vanderbilt

University and electrostatic levitation ion the benchi at the Jet Propulsion Laboratory.

The intermetallic compounds chosen to be studied initially are TiA1 and NiAI. In addition, studies will be done on

pure Ti and pure Ni, as points of reference and because of their stand alone contribution to science. The pamcular

intermetallics are chosen because both exhibit a wide solubility range as seen in their respective phase diagrams and,

within compositions ranges, exhibit a tendency to be unencumbered by competition between alternate phase

selection in the deep undercooling regime.

Nucleation frequencies as a function of temperature will be obtained for each combination of specimen type and

ground-based processing technique. In each case, the nucleation probability distribution and the cumulative

distribution will be constructed from the nucleation frequencies. To do this, a large number of undercooling

experiments on each specimen type will be conducted by each of the ground based containerless methods. From

analysis of the cumulative distributions, the kinetics of nucleation of the solid from the liquid for each specimen

type under each processing condition will be quantitatively defined and examined in comparison to nucleation

theory.

The ordered intermetallic alloys as well as their pure constituents will also be studied in order to determine the

solidification velocity as a function of melt undercooling. The velocity will be determined using ultra high speed

imaging to track the solidification front as it moves through the specimen. In opaque samples this can be done by

monitoring the movement of the thermal field developed by recalescence. An instrument has been developed that

consists of a 10 by 10 array of parallel tapped photodiodes and data acquisition. The system is capable of capturing

data at rates of up to 1 million frames per second and the output from the array is calibrated for conversion to

_j_I_I_II_*_*_ID_i_o_i__o_D_iI_I_e$_o_$_OI_I_D_I_D_t_e_$_I_I_I_Io_I_t_I_I_D_I_I_I_I_j_l_o_I

11-495
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

i,, *e DI * 01 * i i* i I * i *| | i,, a g * * i, iI * tl | mi | i, I, i i. i i |, 11*,,, | | |, _ t g *, | *,. t,,. | i i Di * i * *, t!. |I i | i i mi * I! i i* * *, | _ * | * JI| i, J * I | i | H * i, I _ * ! H i J lea B* i | ii 18, J i i | | i I I I |. I ! _| * I | | !, i ! * i I o J _ *| I i *1_ * l0 * _ II |1_ III |1 ¢ I ! i| ! ¢ I I *| ! * |1,. ¢ I I e I * * I ! * _ J | | * * | I i | i !. i i | i, iJ *

temperature. For each 'alloy and pure element, a plot of the solidification velocity as a function of undercooling

will be developed. This data will be compared to present solidification theories and any areas of discrepancy will be

addressed. Of particular interest are the mechanisms controlling the rate of solidification at various undercoolings.

TASK SIGNIFICANCE:

Intermetatlic compounds and their composites are of considerable interest because of their potential use in high

temperature structural applications. One strong driver tOTthis interest is future goals toT aircraft propulsion

systems. Future aircraft engines will require high thrust-to-weight ratios and low specific fuel consumption, while

remaining reliable, affordable and highly maintainable. Effort involving innovative designs, advanced materials and

processing, and improved design and analysis tools is required to meet Integrated High Performance Turbine Engine

Technology goals for doubling propulsion system capabilities by the year 2005. Benefits of the required increase in

engine cycle temperature must not be offset by increased turbine weight or cooling air. Thus, new materials and

design technologies are needed for advanced high-temperature turbines.

The materials of interest in this study show potential for use in such applications because of their significantly

increased high temperature strength and acceptable low temperature "damage tolerance. It is therefore necessary to

fully understand the nucleation and solidificauon behavior of these intermetallic compounds.

PROGRESSDURINGFY 1994:

During the initial stage of this new grant the study of the solidification velocity as a function of undercooling for

gamma titanium "aluminum was continued. The previously gathered data was reexamined in order to improve the

resolution of the measurements. Also, additional experiments were run for determination of the dependence of

solidificalaon velocity on undercooling.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 0

TASKINITIATION: 9/94 EXPIRATION: 9/96

PROJECTIDENTIFICATION:962-25-08-31

NASA CONTRACT NO.:NAG8-1087

RESPONSIBLECENTER: MSFC

11-496
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

IIII.mllnl10u011111al10010m0111 mlIOlnD01mO mllonmll!llllaHiHio|l J oll!nl.l.lollllmlllllllmmmm OH 1|m_oo_m_umm_mo|o_m1m|o_m1a|_||mom|_11||oa|_a_n1o11m|m|_|_e1_o|_m_mmm_||_1u_m_ m|

Transport Phenomena During Equiaxed Solidification of Alloys

PRINCIPALINVESTIGATOR:ProL Christoph Beckermann University of Iowa

CO-INVESTIGATORS:

H.C. deGroh III NASA Lewis Research Center CLeRC)

TASK OBJECTIVE:

To investigate the macrosegregation and structural inhomogeneities resulting from gravity-induced thermosolutal

convection and solid sedimentation during equiaxed solidification of alloys on a bulk level.

TASK DESCRIPTION;

The melt flow and solid transport phenomena occurring during equiaxed alloy solidification are investigated in

experiments using both metal alloys and transparent analogues. The drag and heat/mass transfer coefficients of

single equiaxed crystals are measured by employing fabricated dendrite models and, in situ using transparent model

alloys. This information is combined to develop a multi-phase/-scale simulation model that allows for the

calculation of the individual solid and liquid motions during solidification and incorporates the detailed phase

interactions on a microscopic scale.

TASK SIGNIFICANCE;

This investigation complements NASA-sponsored research on the influence of fluid flow in alloy casting by

including the important effects of gravity-induced motion of free equiaxed crystals. This combined experimental and

theoretical/numerical study will provide (1) needed fundamental understanding of how liquid convection and the

movement of free equiaxed grains interrelate and produce segregation and structural zones in castings, (2) progress

towards a more complete numerical simulation model of transport and solidification phenomena, and (3) a base for

defining future microgravity flight experiments on equiaxed dendritic solidification.

PROGRESSDURING FY 1994:

1. Solidificadon Experiments

The objectives of the bulk solidification experiments are to determine how convection in the liquid and

settling/floating of tree grains interrelate and result in segregation and structural patterns in castings, and to provide

quantitative data for testing of the numerical model being developed. This will be achieved through a combination

of metallic and transparent model (NH4C"-H20) experiments.

The work on the metallic alloy experiments has concentrated on adapting and instrumenting the Glove Box Casting

Facility and the Bulk Undercooling Furnace in the Microgravity Materials Science Laboratory at the Lewis Research

Center. Experiments with various Pb-Sn alloys were performed, in which cooling rates, thermal gradients, and

grains structure were measured. Modifications were made to achieve a more equiaxed structure. These experiments

are presently being analyzed.

A complete set of transparent model alloy NH4C"-H20 experiments was conducted using a rectangular test cell.

Temperatures were measured both along the walls (for later input into the numerical simulation model) and within

the solution (for later comparison with the simulation results). Recalescence, a phenomenon typical of equiaxed

solidification, was detected. The flow phenomena were recorded using time-exposure photography and shadowgraph

visualization to detect density gradients within the liquid. Solidification was equiaxed, and extensive advection and

sedimentation of solid dendrites were observed. These data are presently being compared to corresponding numerical

simulations.

Additional solidification experiments were conducted using the transparent succinonitrile-ethanol system and the

same test cell.

oo_ta_o_I_I_I_e_o_o_o_o_o_o_oo_oao_am_o_*_o_o_ui_Do_D_D_ioo_u_oo_a_o_nuua_I_i_e_B_a*_u_onuow_a_u_D_o_oono_ea_o_oo_o_o_I_oDo_otoo_non_B_o_m_o_ot_no

11-497
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

illll|llul|mllQIlllll|ll|lllllllllll_lnl|nlll|ll J|llnllll|011111111111111111HIlllllllllnl|lllH mI_I_|i_IllII_|_I_II_e_I;||n_i_;n_ulII1_I_iI_I_|_I_I_I_H_o_|n_I_Ii_II_|!_H_H_II_|_I_e_ne_s_a_nI_nI_

2. Measurements of Interracial Transport Coelt_cients

A key feature of the proposed model is that the interactions between the solid and liquid phases are considered

explicitly through the use of interracial mass, momentum, energy, and solute balances. This, in turn, requires the

knowledge of the drag coefficient and heat/mass transfer coefficients between the melt and the equiaxed crystals

moving and growing in the undercooled melt. It is the objective of this part of the investigation to measure these

coefficients. Generally, they are a complicated funcuon of crystal microstructure, melt properties, relative velocity,

and the number density of crystals present. The present expe_nents concentrate on single crystals, with the

extension to multiparticle systems and packed beds of crystals accomplished through data available in the literature.

Measurements are performed for plastic models of equiaxed dendrites and dendrite fragments, as well as Ibr

transparent model alloy crystals.

A correlation has been developed for the drag coefficient of single equiaxed crystals using measured settling velocity

data for dendrite models fabricated from plastic. The correlation accounts for all relevant microstructural parameters,

including the overall width of the crystal, the crystal envelope sphericity, the interdendritic arm spacings, and the

internal solid fraction -- all parameters used in the numerical simulation model. This also allows for the application

of the correlation to real metallic systems and transparent model alloys, and good agreement was achieved with our

measurements in NH4C"-H20.

The same correlation framework was then extended to multiparticle systems, unifying the above single crystal drag

data with permeability measurements on packed beds of equiaxed crystals available in the literature. The correlation

also provides information on the partitioning between the flows around and through the dendrites before packing.

The correlation has been implemented in the numerical simulation model.

Measurements of the heat/mass transfer coefficients of single growing and settling equiaxed transparent model alloy

crystals are presently underway. A settling column has been constructed that allows for the precise control of the

undercooling and the introduction of equiaxed crystals. Measurements of the growth rate and settling velocity will

be used to calculate the heat/mass transfer coefficient. Both NH4C"-H20 and succinonitrile-ethanol solutions will

be used.

3. Model Studies

A two-phase model of alloy solidification has been extended to include equiaxed dendrites by introducing a new

muiti-phase/-scale concept. The model was t-trst tested for the limiting case of diffusion controlled solidification, as

can be expected in microgravity. The predictions were compared with experimental data available in the literature

for purely columnar, purely equiaxed, and coupled columnar/equiaxed growth. In particular, the coupled

columnar/equiaxed experiments corresponded only approximately to a convection-t_ee situation, making ,t wae

validation of the diffusion model impossible. It was concluded that, given a realistic nucleation model, the

columnar-to-equiaxed transition can be predicted for a variety of alloys, compositions, and cooling conditions. Final

validation of the model, however, must await experiments in microgravity.

Numerical simulations that include melt convection and solid transport have been carried out using the two-phase

model. The primary purpose of these exploratory simulations was to examine the influence of the equiaxed nuclei

density on the solid transport behavior and to compare with results/'or a fully stationary solid phase. The

simulations were performed for solidification of an AI-4wt%Cu alloy in a rectangular test cell coo!ed from the left

sidewall. Three simulations were performed: (a) stationary solid, (b) an average equiaxed nuclei density of 1011

l/m3 and (c) of 109 l/m3. The mushy zone structure was substantially different for all cases. In cases (b) and (c), a

sediment layer of equiaxed crystals formed at the bottom in a manner similar to that experimentally observed. Final

macrosegregation patterns and grain size distributions were also predicted and compared. Presently, quantitative

comparisons between the NH4C"-H20 experiments and corresponding simulations are being attempted.

11--498
STUDENTS FUNDED UNDER RESEARCi_:

BS Students: 0 BS Degrees: ()

MS Students: 2 MS Degrees: 1

PhD Students: 1 PhD Degrees: I

TASK INITIATION: 11/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-25-05-23

RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Beckermann C. and C.Y. Wang. Incorporating interfacial phenomena in solidification models. JOM: The Journal of The

Minerals. Metals & Materials Society. w_1,46, no.l. 42-47 IJanuary 1994).

deGroh II.r, HC.. P.D. Weidman, R. Zakhem, S. Ahuja and C. Beckermann, Calculation of dendrite settling velocities

using a poroqs envelope. Met. Transactions B, vol. 24B. 749-753 (1993).

deGroth, IH, H.C. Undercooling induced macrosegregation in directional solidification. Metall. Trans. A.. vol. 25A.

2507 (1994).

Wang, C.Y., Ahuja, S., Beckermann, C., and deGroth IlI. H.C. Multiparticle interracial drag in equiaxed solidification.

Met. Transactions B, (1994}.

Wang, C.Y. and C. Beckermann, Prediction of the columnar to equiaxed transition during diffusion-controlled dendritic

alloy solidification of alloys. Met. Transactions A, vol. 25A. 1081-1093. (1994).

NASA Tech Briefs

deGroth. III. H.C., Weidman. P.D, Zakhem, R., Ahuja, S.. and Beckermann. C. Calculation on dendrite settling velocities

1.0, User's Manual. COSMIC. Software Technology Transfer Newsletter. NASA Tcch Brief. vol. 1, no.4. 12 (1993).

Zakhem, R., P.D. Weidman and H.C. dcGroh III, On the drag of model dendrite fragments at low reynolds number., NASA

TM 105916, (Feb. 1993).

Proceedings

Ahuja, S., Beckermann, C.. Zakhem, R., Weidman, P.D., and deGroth, III, H.C. "Drag coefficient of an equiaxed dendrite

settling in an infinite medium." Micr/Macro Scale Phenomena in Solidification. HTD-Vol. 218, pp. 85-91 (1992).

Beckermann, C. "Modeling of transport phenomena in mushy zone." Modeling of Casting, Welding, and Advanced

Solidification Processes-Vl, eds. T.S. Piwonka, V. Voller, L. Katgerman. TMS. Warrendale. PA, 181-192, 1993.

Beckermann. C.. Feller, R.J.. Irwin, T,, Muller. H.. Wang. C.Y. "Visualization of sedimentation and thermosolutal

convection during equiaxed alloy solidification." 32nd AiAA Aerospace Sciences IVleeting, AIAA, Paper No. 94-0570,

(1994).

deGroth, III. H.C. "Effect of nucleation and undercooling on macrosegregation in directionally solidified Pb-Sn eutectic

alloys." Proceedings of the First International Conference on Transport Phenomena in Processing, edited by S.I. Guceri,

Technomic Publ., Lancaster, PA, pp, 209-218 (1993).

Wang, C.Y. and Beckermann. C. 'Microstructural development in equiaxed dendritic solidification with convection."

I994 TMS Fall Meeting, Rosemont. IL. 1994,

Wang, C.Y. and Beckermann. C. "Multi-scale/-phase modeling of dendritic alloy solidification." Transport Phenomena in

Solidification, eds. C. Beckermann et al.. ASME. New York. NY, HTD-Vol. 284, pp. 75095, 1994.

i i i Ii i i I iiiii i ill IIii Iiiii I ii I Oil I ill ii iii I lllll I II t III I II IIIIII I II I IIIII 1111II I II I II I I II I I II I U I II I III I II I IIIII I II iI I I I tO I IIIII I II II II I l illl I I I I I II I II III i II III I II III IIII III in lll iii i iii i ii i Iii I I i iii i iiiiii i iiiii ill iiii i lll IIIii IIi i iii i ii i Ill ii

1I--499
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

H.II|l.l.nntna|ll1811.1-t-ln-u|uau H iiinloa|nnllllllollnlool.l.lltlloHoo41o H011QIHIn10U||11| H|IHII0nn0H oH aa|tl|loolloH|olllolHIooll|olloilollooHolaoloo|ll|l||tno||lnoo|! 0110H0|II01HUUnHI01HUlIOH|I0n1001101n0|

Gravitational Effects on the Development of Weld-Pool and Solidification Microstructures in Metal

Alloy Single Crystals

PRINCIPALINVESTIGATOR:Dr. Lynn A. Boamer Oak Ridge National Laboratory

CO-INVESTIGATORS:

S. David

G. Workman

Oak Ridge National Laboratory

University of Alabama, Huntsville (UAH)

TASK OBJECTIVE:

The objectives of this research are to achieve an in-depth quantitative understanding of the role played by

convection-driven and surface-tension-driven heat and mass transport in determining the shape and surface

morphology of fusion weld pools and, thereby, to control the nature of the solidification processes that determine

the microstructural and mechanical properties of welds.

TaSK DESCRIPTION:

By combining ground-based results with those obtained in the low- and high-g environments provided by NASA

aircrafL detailed microstructural information can be obtained through the use of single-crystal alloy specimens, and

both gravitational and surface-tension-driven effects on weld-pool formation and microstructural properties can be

delineated and quantified. The results of these investigations are currently yielding new information that is serving

to advance our level of understanding of various phenomena which determine both weld-pool shapes, mass

transport, and the morphological properties of solidification surfaces.

This research represents a new and innovative approach to the investigation of gravitational effects on melt-pool

shapes, solidification phenomena, and weld microstructures. This approach is based on the application of our

recently developed single-crystal methods for the delineation of solidification microstructural properties and on the

new quantitative analytical methods that have been developed in conjunction with the unique experimental results

that can be obtained through the application of these single-crystal techniques. This approach to the study of weld

and solidification microstructures begins with the growth of macroscopic single crystals of the alloy system that is

to be investigated. As in the case of our previous ground-based studies, Czochralski-grown single crystals of the

pure ternary alloy 70Fe-15Ni-15Cr (a compositional analog of one of the 300 series of stainless steels) are being

utilized.

TaSK SIGNIFICANCE:

The long-term goal of this research effort is to achieve a firm scientific basis for the development of a

comprehensive scientific program in which more-complex solidification and welding experiments can be carried out

on NASA aircraft, on Space Shuttle flights, and eventually on Space Station Freedom. Since the microstructural

properties of weld pools and the distribution of certain impurities within the weld are central to determining the

weld mechanical sllength, these experiments have practical implications regarding a wide range of construction,

fabrication, and manufacturing operations both in space and on earth.

PROGRESSDURINGFY 1994:

A comprehensive set of solidification experiments has been completed in which single crystals of the ternary alloy

70Fe-15Ni-15Cr were utilized in investigations of microstructural formation in stationary melt pools formed by

both electric-arc and electron-beam melting. This alloy is a pure analog of a stainless steel in the 300 series of

commercial stainless alloys. By carrying out solidification experiments in which stationary melt pools were formed

on stainless steel single-crystal surfaces that were oriented to coincide with (100), (110), and (111) principal

11-500
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

,,IB. om H.. HI l|, i|o, i, ,|, if, I I" i. I ,,I ,¢ I I .., I i _Oi, CH ,, r ,,, I.,, ,, J ,, i., i i H, ¢|a ,|I., I. I ,I,., i,i i .., .,, I,' i,, i ,|,. I ,, I. ,|,,,, i' ,..,. Ii ,|I,,,. l I. I ,, a,|.0 i I Of I. ,I, I I¢I m l I m|HIeoJ I*I Illt ¢OI|,|I|IIUtU,¢ J.,.mloi I¢I I,I I Sl I ,I

crystallographic planes, it was possible to carry, out a three-dunensional reconstruction of the dendritic-solidification

microstructures corresponding to melt pools with various shapes. This three-dimensional reconstruction was

achieved by using information provided by optic',d-meudlographs which were obtained by sectioning the

solidification microstructures along various principal crystallographic directions.

Most significantly, in the course ol this research activity, a unique suriace morphology that is present following the

solidification of stationary melt pools formed by either electric-arc or electron-beam melting was observed. This

surface morphology consists, in genera.l, of concentric surface undulations, or "ripples." These undulations begin

at the outer circumference of the melt pools and continue in toward the center with a steadily decreasing diameter.

Experiments using alloy single-crystal specmaens have been initiated for the purpose of studying mass-transport

effects in both low- and high-g environments for stationary melt pools formed in a high-temperature alloy system

such as stainless steel. These investigations have utilized the controlled introduction of a "tracer" element into the

bottom of the melt pool subsequent to its formation. The solidified melt pool is then cross sectioned and

back-scattered-electron elemental analysis is used to map out the distribution of the tracer element in the solidified

melt pool. Although these studies were initially conceived as an independent investigation of mass-transport

phenomena in low- and high-g conditions, subsequent to the investigations of surface undulations noted above, it

was determined that, in tact, the nature of mass transporl m these systems and under these conditions is apparently

not independent of the elrecks leading to the formation of surface ripples on solidified stationary melt pools.

Accordingly, the tracer technique, which has been developed m the course of this work, is now being applied to a

combined investigation that includes an in-depth study of the formation of surface undulalaons and mass transport in

stationary melt pools lormed by electric-arc, electron-beam, and laser lneltmg.

A new laser-melting system has been assembled by co-investigators Gary Workman and Guy Smith at the

University of Alabama - Huntsville, and this new, more-powerful system will be used in a series of melting and

solidification experiments to be perlormed in the latter part of October, 1994 on the KC-135 aircraft` The melt-pool

shapes and ass{eciated microstructural properties and the surface morphologies formed during the low- and high-g

portions of the KC-135 flight path will be investigated in the course of these experiments.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 2/93 EXPIRATION: 2/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-25-08-23

MS Students: 1 MS Degrees: 1 NASA CONTRACTNo." H-13059D

PhD Students: 0 PhD Degrees: 0 RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Sipf, J.B., Boatner, L.A.. and David, S.A, Solidification microstmctures m single-crystal stainless steel melt pools.

ORNL/TM, no. 12623. (March, 1994).

Presentations

Boatner, L.A., David. S.A.. and Workman, G. "Gravitaional effects on the development of weld-pool and solidification

microstructures." NASA Microgravity Materials Science Conference, Huntsville, AL, May 24-25, 1994.

Sipf, J., David, S., Boatner. L. A., Gardner, M.. and Baldwin, A. "Development of microstructures in single-crystal

stainless steel spot welds." 1994 International Metallographic Contest. Second-in-Class Award, Class 1-Light

Microscopy - Metals and Metal Alloys, Oak Ridge National Laboratory, Oak Ridge, TN.

,iiiiiiii*IIIIIIIIIiiiiiiiii iiiIIIiiiiI! IIiIIIIiIIIIIIIIIIIIIiiiiIIIIiI,IIiiiiIIiisiIIiiiiIIIIIIIiiIiI*II*IIfIiiiiiiIIiiiiii iIIIIIIii,, iiiii llIiIiiIIIiiIIIii,i*IIIII*IIiiiIIiiii iiiIIIIIIiIiiIIIIII*IIIIIIIIIIIII iiiiiiiiIiiiIiiiiiIIIIIIIfIf*IIIIi

!I-501
Modelling of Convection and Crystal Growth in Directional Solidification of Semiconductor and

Oxide Crystals

PRINCIPALINVESTIGATOR:Prof. Robert A. Brown Massachusetts Institute of Technology (MIT)

CO-INVESTIGATORS:

D. Bornside Massachusetts Institute of Technology (MIT)

TASK OBJECTIVE:

The research effort tocu_s on the development of a detailed understanding of the interactions of heat, mass and

solute transport on the quality of crystals grown from melt by the vertical Bridgman (VB) method. Both

semiconducting "alloy (GeSi) and oxide (Bismuth germenate) crystals are being studied.

TASK DESCRIPTION:

The research is aimed at developing a detailed simulation tor VB crystal growth systems for semiconductor and

oxide materials that begins to relate macroscopic analysis of heat, mass, and solute transport with the microscopic

properties of the grown crystal. The analysis and simulation tools developed will be applied to the analysis of

several crystal growth systems. The binary alloy GeSi and the pseudo-binary BGO Bismuth germenate are selected

for analysis of VB growth. The research is divided into three sections:

• Development of integrated model for vertical Bridgman growth,

• Parallel processing and simulation of three-dimensional convection,

• Application to GeSi alloy crystal growth, and BGO crystal growth.

Fun "damental understanding of the interactions of heat, mass, and solute transport on the quality of crystals grown

from the melt is important in the design and control of systems for crystal growth in microgravity and for the

interpretation of the results of experiments perlormed both on Earth and in space. The research program focuses on

the development of the detailed analysis of these features in the vertical Bridgman (VB) crystal growth of

semiconductor crystals and oxide materials used in optoelectronic applications. The analysis has two parallel goals:

to develop the t_st integrated model and numerical analysis/'or the growth of these materials that accounts tot the

details of the design and operation of the furnace; and to link the predictions of the macroscale analysis of heat

transfer and convection with the quality of the crystal as measured by the number of crystallographic detects and the

compositional homogeneity of the material. The research integrates several aspects of research that are ongoing at

M.I.T. to accomplish these goals: the development of numerical analysis for integrated heat transfer throughout a

high temperature furnace, including internal radiation in a semitransparent material; the modeling of dislocation

motion and multiplication in semiconductor materials; and applications of new robust algorithms for parallel

computation.

The analysis of coupled furnace design and the prediction of material quality will be applied to two distinct crystal

growth technologies that have potential application for crystal growth in microgravity: the growth of GeSi

semiconductor alloys, a substrate material used for superlattices, and the growth of Bismuth Germanate or BGO, a

scintillating oxide material used in high energy detector applications.

TASK SIGNIFICANCE:

The techniques lor analysis and the quantitative insights developed in this research have broad application to a

variety of ground-based and space flight experiments supported by NASA and its European counterpart, ESA.

Many of the previous research results conducted in this research area represent theoretical collaboration with

experiments supported by NASA. These interactions between detailed modeling and experiments are crucial to the

11-502
designofwell-controlledxperimentsforspace, a.swellasopmnizedcrystalgrowthonEarth.Thedevelopment of

auser-ti'iendlystmulatorforVBgrowthsystemswillbeadirectresultofthisprogramandwillbemadeavailableto

othersintheresearchcommunity.

PROGRESS DURINGFY 1994:

The research program described here focuses on the development of the computational tools lor detailed an',dysis of

the vertical Bridgman crystal growth system for the growth of both semiconductor and oxide crystals. The research

links several components to accomplish these goals. The first is the development of very accurate and efficient

methods lor the computation of diffuse-gray radiation in the furnace enclosure and of radiation in a semitransparent

material for the case of oxide growth. The second is the development of advanced computational methods capable of

computing three-dimensional convection in the melt coupled with realistic furnace models for analysis of melt

convection during growth under terrestrial and microgravity conditions. These algorithms will be based on the

application of finite element methods for the solution of the integrated heat transport and convection models for

vertical Bridgman growth using MIMD parallel computers.

Research has been directed toward the development of computational tools needed for the vertical Bridgman

simulator described above. To date the tollowing developments have been made:

1. A new object-oriented method tbr the computation of view factors/'or axisymmetric, diffuse-gray radiation has

been developed.

2. The basic elements of a parallel implementation of the finite-element/Newton method for solving transport

problems has been completed and demonstrated for buoyancy-driven convection.

Object-Oriented View Factor Calculation

Accurate calculation of view factors for use in the diffuse-gray radiation calculation is one of the most important

elements of calculation of high temperature radiation in crystal growth systems. Two features of the numerical

method are needed to insure accuracy of the radiation calculatmn: free finite element surface discretizations and

accurate calculation of the view factor form one surface element to another. Most previous calculations of crystal

growth furnaces use some form of the Facet algorithm first modified by us tbr this application. Here the view

factor from any fiat surface element to any other is computed by a double area quadrature, once the possibility of

blocking by another surface element is tested for each element. The computation of the blocking is the most time

intensive part of the algorithm, scaling as O(N_), where N_ is the number of surface elements in the radiation

enclosure.

We have developed an object-oriented method (tOM) that takes account of the axisyrnmetry of typical furnace

geometries and that groups surface elements into conical and cylindrical objects, thereby drastically reducing the

blocking calculation. The tOM is based on Nusselt's projection method for computing view factors by projection

on the surface of a hemisphere. The tOM method scales as O(No_iN,), where No_j is the number of objects in the

enclosure; usually No_, << N,. Simulations for model systems and for realistic crystal growth furnaces have verified

this scaling.

parallel Implementation of the Finite-Element/Newton Method

Robust numerical solution of very detailed simulations of crystal growth fumaces and three-dimensional convection

in the melt present computational problems that are at the leading edge of supercomputing today. To advance these

simulations will require the application of parallel computing to the solution of the physiochemically complex

transport models that are needed to model crystal growth systems. A major goal of this program is the development

of a finite-element based methodology tot this purpose. Our approach is to use finite element methods to reduce

these models to large systems of algebraic equations and to solve these equations by Newton's method. Each

Newton iteration requires the solution of a large set of algebraic equations which is the heart of the algorithm. We

do this by LU decomposition using domain decomposition and nested-dissection to distribute the work of LU

11-503
decomposition over the multiple processors of a M1MD parallel computer. Our implementation of LU

decomposition is among the fastest ,algorithms of its type available. We have used this algorithm to solve model

problems in steady-state and transient buoyancy-driven llow and have demonstrated the robustness of the algorithm,

_LSwell _s the linear speed increa.se of the algorithm with incre_sing number of processors.

Dynamics 9f Sm011-Scale Floating Zones

Small-scale floating zones are used in a number of microgravity experiments and offer a very interesting case study

in the dynamics of meniscus-defined crystal growth. The goal of this project has been to develop detailed models

and numerical simulation tools for the analysis of steady-states, their stability, and nonlinear dynamics of

small-scale floating zones. The thermocapillary models include both steady-state and transient analysis of heat

transfer in all phases, convection in the melt, the shapes of the melt/crystal and melt/feed-rod interfaces and the

shape of the meniscus. Finite-element analysis is used to discretize the model and Newton's method is used to solve

the nonlinear algebraic equation set that arises in the steady-state calculation and at each time-step of a fully implicit

time integration. Zone stability is tested by linear stability theory implemented in the finite-element formalism

using an Arnoldi algorithm to compute the most dangerous eigenvalues of the linear stability problem for each set

of operating conditions. Our initial results describe the dynamics of the zone in the absence of convection in the

melt. Here the interplay between surface tension, which limits the zone length through the Rayleigh limit, and heat

transfer are shown to lead to a new oscillatory mode for instability in the floating zone shape in which the zone

length oscillates with growing amplitude until the zone breaks. This instability occurs before the maximum zone

length that is predicted by the Rayleigh limit for an ideal cylindrical zone. Closed-form linear and nonlinear

analysis demonstrate that the zone dynamics associated with the Rayleigh limit for growing floating zones is "altered

from the conventional dynarmcs seen for captive cylindric_d drops used as model systems.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 7/93 EXPIRATION: 7/96

PROJECT IDENTIFICATION: 962-21-08-17

NASA CONTRACT NO.: NAG8-961

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Mehrabi, R., and Brown, R.A. An incomplete nested dissection algorithm for direct solution of finite element

discretizations of partial differential equations. J. Sci, Computing, vot. 8. 373-387 (1993).

Proceedings

Brown, R.A., Bornside, D.E., Sinno, T., and Zhou. W.-G. "Modelling of bulk crystal growth of silicon." Proceedings of

the Eighth International Conference on Heat Transfer. Brighton, England. August, 1994.

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11-504
Microstructure Formation During Directional Solidification of Binary Alloys Without Convection:

Experiment and Computation

PRINCIPALINVESTIGATOR:Prof. Robert A. Brown Massachusetts Institute of Technology (MIT)

Co-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

A combination of experimental and theoretical research will be aimed at developing a predictive understanding of

cellular and dendritic microstructures of dilute binary alloys and lamella spacing in the growth of eutectics formed

during thin-film solidification. The results will form the basis for prediction of the dependence of microstructure

formation on macroscale properties of bulk solidification systems, such as the imposed temperature gradient and the

sample growth rate.

TASK DESCRIPTION:

The extensive theoretical and experimental research on microstructure formation point to the formation of cellular

microstructures in binary alloys and lamella eutectics as being formed under conditions of long time-scale,

spatiotemporal chaos in the pattern. These patterns involve a band of wavelengths that evolve with changes in the

operating conditions, such as growth rate and temperature gradient, and include very long wavelength interactions

through which the pattern communicates over length scales much larger than the characteristic cell size. The

outstanding problem that will be addressed in the research is to begin to construct mean field models for

solidification microstructure that are based on microscopic mechanics of individual elements in the microstrucure.

Experimental, theoretical and computational studies will be conducted that will lead toward this goal. These

elements of the research plan are:

• Experimental studies of spatiotemporal chaos in cellula_ solidification and the role of externally applied forcing

functions on regularization of the pattern;

• Extension of the analysis of wavelength selection to thin-film eutectic solidification;

• Experimental studies of lamellar eutcctic growth in thin-film solidification; and

• The development of stochastic and mean field models for pattern formation in directional solidification.

The microstructurc of metal alloys formed ttom directional solidification plays an important role in the mechanical

and electrical properties of these materials. This investigation describes experimental and theoretical research aimed

at developing a predictive understanding of cellular and dendritic microstructurcs of dilute binary alloys and the

lamella spacing in the growth of eutectics t'o_ed during thin-film solidification. The combination of experimental

and theoretical results will form the basis for prediction of the dependence of microstructure formation on

macroscale properties of bulk solidification systems, such as the imposed temperature gradient and the sample

growth rate. The experimental studies are carefully designed so that bulk convection, driven by density gradients, is

unimportant. In this way, the results are applicable to gravity-free experiments that will be undertaken during space

flight. The theoretical framework tbr understanding nonlinear pattern formation during solidification is so complex

that there is little hope of unraveling the mechanisms/or pattern Ibrmation in the presence of convection without

rigorous analysis and experiment in the absence of convection. The thin-t-tim experimental geometry offers the

only mechanism for accomplishing this goal on Earth.

TASK SIGNIFICANCE:

The research has the promise of making significant progress towards the development of a theoretical framework for

characterizing the formation of microstructure in alloy solidification. The experiments and microscale calculations

11-505
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

noil ooaoo i luaaooaoaaoo I Ilia on ai nl Ha oil aalllllallal iii ii Il aI I al I al I |an oan i| i aaan o81 g||ale In| oooouan I aal aonaoaalia o| uuo eui inuann! oaannlanno I i II I al I III III I1all nno l ao lea I al at I oI liltS11 |al |aala Ill I1| I Io I III I aal$1a|a ioolloaooloolo|aooao|aaoaoag oat oo

to be conducted will lay the tbundation lot detailed description of the mechanisms for length scale adjusmaent in

cellular and lamellar eutectic growth. The development of kinetic theory, tbr describing the evolution of the

microscale will give the connection between processing variables and microscale formauon that is necessary for

adaptation of the theory to practice in industrially important systems, and will provide a framework for the

characterization of alloy systems for microstructural modeling parameters.

PROGRESSDURING FY 1994:

Research in FY94 focussed on two fronts: refinement of experimental methods for the measurement of the

dynamics of large collections of ceils during solidification of a binary alloy and the development of simple models

that exhibit dynamics similar to what is observed in the experiments.

Experiments Using Thin-Film Solidification System

During Fy94 we have retined the experimental methods for solidification of succinonitrile-acetone samples in a

large-scale thin-film directional solidification system developed by us (C.T. Lee and R.A. Brown, Physical Review

B 47 4937 (1993)). This system is unique because it allows for long-time (approximately 5000 diffusion time

scales) solidification of well-controlled samples. Experiments this year have focussed on the development of

Fourier Transtorm Infrared Spectroscopy (FTIR) as an analytical measurement of the composition of dilute acetone

in succinonitrile samples and the use of the system lbr precise measurement of the conditions for the onset of

morphological instability in the thin-film solidification system. Data from these experiments have been compared

with the constitutional supercooling criterion and the stability boundary from the complete linear stability analysis

for the onset of morphological instability. The comparison is excellent for the critical value of the growth rate (V

,_0 for a given alloy concentration (co) and temperature gradient (G). However, the structure of the cells seen in the

experiments neither resembles the sinusoidal ceils predicted by the linear stability analysis nor has a dominant

component of the length scale of approximately 500 [am predicted by the linear analysis to be most dangerous.

Instead, the length scales of the cells are approximately 100 lain and the ceils are irregular. We are in the process of

developing a new interracial imaging system for rapid statistical processing of the cellular structures for quantitative

determination of the inteffacial morphology.

Modelling of Nonlinear Dynamics of Cellular Solidification

Nonlinear simulations of large collections of cells lor solidification over long time scales are exceedingly expensive

and make employing any of the tools for calibrating the degree of spatiotemporal chaos in the pattern difficult to

employ. Accordingly, we have begun to search/or simple nonlinear amplitude equations which give the same

qualitative nonlinear dynamics as the solutions from the full model that results from solving continuum transport

models for solute and heat transfer coupled with the Gibbs-Thomson condition for interfacial equilibrium. When the

temperature field is held fixed, this description is known as the Solutal Model. Several features of the nonlinear

dynamics in the Solutal Model need to be captured by the amplitude equation:

(1) The neutral stability curve must be very fiat so that a range of spatial wavelengths go unstable at values of the

dimensionless growth rate (the control parameter) that are only slightly above the most critical value.

(2) The steady-state nonlinear solutions of the equation must demonstrate the secondary bifurcating pattern seen in

the Solutal Model and which is responsible/'or the rapid decrease in the wavelength from the critical value for small

increases in growth rate.

(3) The dynamics of large collections of ceils should demonstrate the dynamics involving the tip splitting of cells,

which leads to the birth of new cells and the death of cells between the grooves of others.

We have developed a nonlinear evolution equation that demonstrates these features. It combines a non local linear

operator - expressed as an integral operator in real space - with a quadratic nonlinearity similar in form to the

Kuramato-Sivashinsky equation. We are in the process of studying the weakly and strongly nonlinear dynamics of

this class of equations using both asymptotic and numerical methods.

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II-506
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

HIJ;IIIIIIIIIIIIIIlUtlIIIIIIlUtlIIO011 Jl Jllll|lllllltlaOIIJOI.tlllJlIHIJllJJlJlJllJl*l.lJlllljllllOJl Jllll.l"llltl|llJJJJlll.lJOIIlllllllOIllllll JllJllJlllllll|llll ill JlJJ;O|IIOIJlIJI|all JJOJllllllelllllaOIIll JlHlllllllUll.l.m.b.I

Effect of Gonv_qign on Evolul_ion of Cellular Morphologie,s

The role of convection in effecting the evolution of cellular morphologies from the onset of morphological was

investigated by two-dimensional numerical simulations in which thermosolutal convection was added to the Solutal

Model described above. The most tmportant finding from these calculations was the difficulty associated with

determining the difference between the so-called morphological and convective modes for instability for finite

amplitude cells. We have demonstrated that nonlinear states created by both types of instabilities lead to cells

separated by very deep grooves for conditions only slightly in excess of those for neutral stability. This work is

being prepared for publication.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

Phi) Students: 2

TASK INITIATION: 7/93 EXPIRATION: 7/96

PROJECT IDENTIFICATION: 962-25-08-25

NASA CONTRACT NO.: NAG8-962

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Tsiveriotis, K., and Brown, R.A. Nonlinear, local dynamics of the melt/crystal interface of a binary alloy in directional

solidification. Physical Review B, vol. 48, 13495-13501 (1994).

Tsiveriotis, K., and Brown, R.A. On the long time scale dynamics observed in directional solidification of a binary alloy.

Physical Review B, vol. 49, 12724-12737 (1994).

11-507
Evolution of Crystal and Amorphous Phase Structure During Processing of Thermoplastic Polymers

PRINCIPALINVESTIGATOR: Dr. Peggy Cebe Massachusetts Institute of Technology (MIT)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

Our objective is to study microstructure evolution during melt processing and secondary thermal treatment of high

performance thermoplastic polymers which are candidate materials for advanced composite applications. We will

investigate formation of structure in both the crystalline and the amorphous phases. The purpose of the study is to

determine the effects of processing conditions on the resultant structure and physical properties of thermoplastics.

We hope to address the manner in which self deformation stresses affect the microsm]cture of the solidifying

polymer melt. Processing in a microgravity environment will impose very different stress states on molten

polymers during solidification, compared to ground based processing conditions. Dependence of polymer

microstructure and physical properties on processing conditions can more easily be predicted and controlled under

microgravity conditions where self delormation forces are avoided.

TASK DESCRIPTION:

Present ground based processing methodologies requires gravity compensation to support the processed piece during

solidification. Therefore nearly all melt processing approaches (eg., extrusion, film blowing, fiber drawing) involve

very rapid quenching of the molten material to avoid imposing self deformation stresses an the melt. Rapid

quenching results in inhomogeneous cross-sections, since the center of the piece cools more slowly than the

exterior. In a microgravity environment, it would be possible to use very slow melt processing techniques to

obtain more uniform microstructure throughout the section, minimizing the morphology gradient between the skin

and the core of the section.

The proposed research is a ground based study of slow melt processing in the gravity environment. We will process

thermoplastic polymers by solidification from the melt without gravity compensation. First we will use real-time

x-ray scattering at elevated temperature to study the kinetics of solidification. Then we will examine the resultant

microstructure at room temperature after processing. Self deformation stresses on the melt will be studied to

determine the effects of gravity on the development of crystalline structure and morphology from the (stressed)

amorphous melt. We will characterize the unit cell structure of the crystal phase, the disposition of unit cells

within the crystals, and the organization of crystals into larger units such as spherulites, fibrillar bundles, or

shisla-kebab structures. We will also study the amorphous phase structure to determine degree of chain alignment

and the amount of rigid vs. mobile amorphous phase. Additionally, the location of rigid vs. mobile amorphous

chains with respect to the crystals will be examined.

The principal approaches used in this study will be real-time wide and small angle x-ray scattering, which will be

performed at the Brookhaven National Synchrotron Light Source and in our in-house x-ray laboratory. In addition,

we will use differential scanning calorimetry, optical microscopy and birefringence, optical waveguide prism

coupling, scanning electron microscopy, and dynamic mechanical spectroscopy to characterize the polymers after

processing. Standard mechanical tests, such as stress-strain and impact resistance measurements, will be used to

study the performance of the test pieces. One unique aspect of the proposed research is the combined study of both

the crystal and the amorphous phases. We will be concerned not only with the nucleation and growth of crystals,

but also with residual stresses and chain alignment in the amorphous phase.

_;|_|_!e_!__!|__|!|___|______!||!__|__!e___!_____|___|__|!_!__!__!__!__!__||a|____!|____!________||__|__|!_|_!|__|_||_||_|__|__!__!e_!_!__||_________|__|!_e|_|!____|!!|!!!!_||_|!_!!_!|!!!_!!_e|_|__|_!|_!|_____________!|_!;__|______;___!e____|__

il--508
TASK SIGNIFICANCE:

Our ultimate goal is to contribute to a fun "damental understanding of microstructure evolution in thermoplastic

polymers solidifying under intluence of sell deformation stresses, and to determine the ameliorating effects of the

microgravity environment. Once we know the effect o[ self deformation stress during processing, we will be better

able to predict the solidification behavior of polymers in the microgravity environment. This will lead to

development of unique processing applications that capitalize on the microgravity environment. Complemetary

experimentation under reduced gravity conditions would later be proposed to be performed on the Space Shuttle, or

on Space Station. Ground based facilities, such as drop towers and KC-135 would not provide the capability lOT

re'd-time studies of microstructure development under practical processing conditions.

PROGRESSDURING FY 1994:

We are awaiting the start of this project in late 1994, or early 1995.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/94 EXPIRATION: 12/96

PROJECT IDENTIFICATION: 962-26-08-12

NASA CONTRACT NO.:NAG8-1110

RESPONSIBLE CENTER: MSFC

11-509
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

i I lll I I Ill llllll I I lllll aIII I llllllllll ill ,U Illl I Illllll I II I I II aI i aIll Ill U IIIII l lOll Illi I lllnlllllllilllllllltlillOllllOllOnllll i l lllllllllil I l lOlllnlllllli ill I I I,llllll I Ill l ltlllll I llllllltl III I Ill Oil I ltll Ill I llllll Ill Oil Ill Ill Ill I I III I I I l

Optical Properties for High Temperature Materials Research

PRINCIPALINVESTIGATOR:Dr. Ared Cezairliyan National Institute of Standards and Technology (NIST)

CO-INVESTIGATORS:

S. Krishnan

J. McClure

Contamerless Research, Inc.

National Institute of Standards and Technology (NIST)

TASK OBJECTIVE:

The objective of this research is to obtain definitive values for the normal spectral emissivity of selected

high-melting-point metals by two independent techniques in order to provide a founclation for reliable radiometric

temperature measurements in materials research at high temperatures, both in microgravity and on the ground.

TASK DESCRIPTION:

The research will include accurate measurements of the normal spectral emissivity of selected metals near and at

their melting points in a series of subsecond pulse-heating experiments in which the emissivity will be determined

at two laser wavelengths in the range 0.5-0,9 pm by two independent techniques involving high-speed pyrometry

and laser polarimetry, respectively. The simultaneous measurements by the two techniques on the same specimen

will minimize a number of major experimental uncertainties, in particular those arising from specimen surface

conditions and specimen purity.

TASK SIGNIFICANCE:

The results of this research will enable the establishment of reference values for normal spectral emissivity (also

leading to high temperature radiometric standards) which are critically needed for accurate temperature measurements

in materials research on high-temperature liquids and melts and in the determination of their thermophysical

properties at high temperatures, under either microgravity or terrestrial conditions. In addition, the proposed work

will resolve the current major controversy in the scientific literature regarding the wavelength dependence of normal

spectral emissivity of metals at and near their melting points.

PROGRESSDURING FY 1994:

The laser polarimeter developed by the Containerless Research Inc. was integrated into the millisecond-resolution

pulse-heating sytem at the National Institute of Standards and Technology. The required modifications in the

polarimeter and the pulse-heating system were made. A new digital data acquisition system was added to the system

and computer programs were prepared for processing of data. Combined operation of the entire system, including

the polarimeter and pyrometer instrumentation was tested. Preliminary measurements of the normal spectral

emissivity in the red region (600-650 nm) have been performed on selected metals in their solid phase (Mo, W) and

at their melting temperatures (Ni, Zr). For the tubular Mo specimen, the agreement between the emissivities

obtained by the two independent methods (pyrometric and polarimetric) in the temperature range 1600-2400 K was

2-3%. Experiments on a solid cylindrical W specimen in the range 1700-3000 K yielded emissivity values from

polarimetric data in agreement, within 2%, with data reported in the literature. Experiments on Ni and Zr strips at

their melting temperatures yielded emissivities which show a reasonable agreement (2-4%) between the results

obtained by the two techniques.

The preliminary experiments suggested improvements in the system. The improvements in the pyrometer and

polarimeter have already been completed; those in the experiment chamber and specimen preparation are underway.

Alter the completion of all the improvements, definitive accurate measurements of the normal spectral emissivity in

the red region will be performed on selected refractory metals (such as Mo, W) as well as industrially important

metals (such as Fe, Ni, Ti). Similar measurements will also be performed in the near infrared region (around 900

_u_n_u_u_o_n_nn_q_n_i_n_n_n_n_o_nn_nn_n_u_n_nn_n_n_nna_nn_u_q_o_B_n_u_u_u_n_

II-510
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

io_e_1"_a_aana_ola_o|_o_o_n_I_oo_Hao_aoi_o_aooiu_|olji_joaoo_ooi_o_o_ u oH o_Hm_H_ona_ooIoo_u_1no_o_aao_u_I_H_uIuII_oI_Hooan1nH_o_uouHIn_o_oo_oI_H_o|Ho_ oloullotl.laona.alllllll

nm). The results of successful experiments will assure the reliability of direct measurements of normal spectral

emissivity with the laser polarimetric technique and will provide much-needed accurate data on the emissivity of

selected high temperature materials.

STUDENTS FUNDED UNDER RESEARCH: TASKINITIATION: 3/93 EXPIRATION: 3/96

PROJECTIDENTIFICATION:962-25-08-27

NASA CONTRACTNO.: H-|8067D

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Cezairliyan, A., and Krishnan, S. "Optical properties for high temperature materials research." NASA Microgravity

Materials Science Conference, Huntsville, AL. May 24-25, 1994.

Cezairliyan, A., Krishnan, S.. and McClure. J.L. "Laser polarimetric and spectral radiometric measurements of the normal

spectral emissivity of high temperature solids in pulse-heating experiments." 12th Symposium on Thermphysical

Properties. Boulder. CO. June 21. 1994.

11-51 1
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

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Fluid Mechanics of Directional Solidification at Reduced Gravity

PRINCIPALINVESTIGATOR: Prof. Chuan F. Chen University of Arizona

Co-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The primary objective of this research is to provide ground-based support for the Casting and Solidification

Technology (CAST) flight experiment, flown on IML-1 in January 1992. The secon "dary objective of the proposed

research is to examine the stability phenomena associated with the onset of freckles and the mechanisms li)r their

subsequent growth and decline (to the eventual demise of some).

TASK DESCRIPTION:

The locus is to study the convective motion and freckle formation during directional solidification of NH4C1 from

aqueous solution at simulated parameter ranges equivalent to reduced gravity. This will involve state-of-the-art

imaging techniques and mathematical models for the prediction of the observed phenomena.

TASK SIGNIFICANCE:

Once the instability phenomenon that causes the onset of freckles in the casting of alloys is understood, then we

can devise means to manufacture castings tree of defects, both in space and on earth.

PROGRESSDURING FY1994:

We have successfully carried out an experiment using x-ray tomography (CAT Scan) to determine the solid fraction

distribution in a growing mushy layer in a NH4CI solution being directionally solidified from below. The results

show good agreement with the prediction of Amberg and Homsy (Journal of Fluid Mechanics. 1993). The results

,also show, contrary to intuition, there is a significant decrease of solid fraction towards the bottom of the tank

where the temperature is the lowest. This occurs at the later stages of the solidification process when the chimneys

are tully developed. As a result, the increase in local permeability can be as much as 50% thus providing a passage

for the fluid supplying the plumes to flow along the bottom of the mushy layer.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 5

TASK INITIATION: 4/91 EXPIRATION: 3/94

PROJECT IDENTIFICATION: 962-25-05-21

NASA CONTRACTNO.: NAG31268

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Chen, C.F and Chen, C.C. Effect of surface tension on the stability of a binary fluid layer under reduced gravity. Physics

of Fluids, vol. 6 no. 4, 1482-1493 (1994).

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11-512
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

Microgravity Chemical Vapor Deposition

PRINCIPAL INVESTIC_TOR:Dr. Ivan O. Clark NASA Langley Research Center (LaRC)

CO-INVESTIGATORS:

W.A. Jesser

P.V. Hyer

E.J. Johnson

University of Virginia

Lockheed Engineering & Sciences Co.

Lockheed Engineering & Sciences Co.

TASK OBJECTIVE:

This research will develop a better understanding of the scientific principles underlying chemical vapor deposition

(CVD). The proposed research will determine to what extent microgravity can elucidate and separate these

competing phenomena and will form the basis for a proposal to perform a series of flight experiments to more tully

elucidate these scientific principles.

TASK DESCRIPTION:

Ground-based experimental and numerical investigations will provide both basic scientific intbrmation on the heat

and mass transfer effects central to the CVD process and define specific follow-on reduced-gravity investigations.

This multi-pronged approach will maximize the utilization of available resources and capabilities. In the numerical

modeling, both finite'difference and spectral element techniques will be used and the predictions compared. In the

experimental phases of the effort, a horizontal CVD reactor design will be used for the growth of a model material,

such as aluminum, and a commercially important material, lnP. Laser velocimetry measurements of the flow fields

in the reactor will also be performed.

TASK SIGNIFICANCE:

CVD is an extremely important industrial technique with applications in the fields of semiconductors, optics, and

corrosion resistance. The nature and quality of the layers formed are dependent on mass and energy transport as well

as homogeneous and heterogeneous chemical reactions and nucleation. Commercial CVD processes currently

employ reactors developed through decades of empirical trial and error. Scientific understanding of the CVD process

is limited by the difficulty of separating the heat and mass transport due to externally forced convection and that of

the internal processes of buoyant thermal convection, buoyant solutal convection, and thermal (Soret) and solutal

diffusion. There is also forced convection due to volume changes arising from both reactive chemistry and thermal

effects. A better understanding of these eft'eels is essential to achieve desired improvements in perfection,

uniformity, and size of grown layers and to provide an engineering design basis for these systems.

PROGRESSDURING FY1994:

The design of the test vessel is being refined using a parametric numerical study of geometric vs analytical

resolution requirements for measuring the reactor effects. A candidate organometallic material has been selected and

efforts are underway to develop the thermophysical properties database necessary to accurately model deposition.

Thermal imaging techniques have been applied to a model chemical vapor deposition (CVD) reactor. The thermal

imaging provided much improved boundary conditions for use in the numerical modeling effort. It also

demonstrated that jets were present in the reactor when hydrogen test gas was used and that the thermal image of

these jets could be used as a diagnostic tool to improve the repeatability of experiments in CVD reactors.

i i i i i ill ill i i i i i oi i oooo i ii in ill I oi i i i i i i i i i i i i igai i i i i i l ol i I I I oI ouI I I II nI II oI Ii i uoI I OI oi no aoI II i! I Ol Oil i gi i oi ill i I i l i ai i i i l aI Ill Ill I IOI I OI OI I Ill lie I oIl I III I I i ai I la i oOI iI! i gOi i oi oi i i i noi i iol i ooaI I aoIII I IooOI I I I I oui I II o, I I ooI ai! oii o! i o! I iii o IOI i !

11-513
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 11/92 EXPIRATION: 11/95

PROJECT IDENTIFICATION: 962-21-06-09

RESPONSIBLE CENTER: LaRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Black. L.R.. Johnson. E.L. Hyer, P.V.. Culotta, P.W.. and Clark. 1.O. "Thermal and fluid effects on MOCVD in a

horizontal reactor." ACCG/West: 13th Conference on Crystal Growth. Fallen Leaf Lake. CA. June 7-10, 1994.

Clark, I.O. "Thermal diffusion effects in chemical vapor desposition." SIAM Conference on Emerging Issues in

Mathematics and Computation from the Materials Sciences, Pittsburgh, PA. April 18-20. 1994.

Clark. I.O., Jesser. W.A., Hyer, P.V., and Johnson. E.J. "Microgravity chemical vapor deposition." Proceedings of the

Microgravity Materials Science Conference, Huntsville, AL, May 24-25, 1994.

Presentations

Black. L.R., Johnson. E.J., Hyer. P,V.. Culotta. P.W.. and Clark. I.O. "1994 Gordon Conference on Crystal Growth,

Proctor Academy, Andover, NH. June 27-July l, 1994 (poster)." Thermal and fluid effects on MOCVD in a horizontal

reactor.

i Ill I Ou! OOOOOOIIII OOOaOnI *l I I lO| oo|O ! OI! oaI O0OO01UOI nOI aO I n_nuonnoI uoi noi nt na| uai i i oo I! t I I t n! on ! in ! OI nOI ao! o! Ooaoo! ! oI ol ! oa! oI goin oi! auI Io ! oo! oi oo! ugqwt! olamIIm Ira OI OIOI I I! Ola OOI O! aoII o|oo ooo I o! ooooI! oooIII ! O! I OI !Ol! OO! |1 Ill I IOil Ug! ! OI OIO III OI OI I |

I1-5 1 4
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

,I,,I,II,H u_|*_**_*_*|_H_"_*I_*_H_Hi*_*_m_iHi"_"_t ,.,,11.,,,1,,1,1,.,,**,1.1 _*_B_1_|_|_**_"_|_1_B_|_"_**b_"_*_H_*_"_H_|i_"_|_"_*_m_

Glass Formation and Nucleation in Microgravity: Containerless-Processed, Inviscid Silicate/Oxide

Melts (Ground-Based Studies)

PRINCIPALINVESTIGATOR:Dr. Reid F. Cooper University of Wisconsin, Madison

CO-INVESTIGATORS:

J.H. Perepezko University of Wisconsin, Madison

TASK OBJECTIVE:

1. Nucleation by internal oxidation or reduction of transition metal-bearing silicate glasses and melts.

If a change in valence state of a transition metal cation wit]am a silicate melt is associated with a change in its

structural role within the melt, one might be able to effect internal homogeneous nucleation within the melt via a

change in the external environment, for example, by a redox reaction. Critical to the hypothesis is the nature of

transition metal cations to make the melt into a semiconductor: Conduction electrons or electron holes are majority

defect species and thus serve to decouple cation and anion diffusion fluxes that occur in an oxygen chemical

potential gradient. One consequence is that oxidation or reduction reactions can occur internally (i.e., within the

body of the melt) instead of solely on the surface. These reactions can result in the destabilization of the melt such

that crystallization reactions occur in finely (nm-scale) dispersed regions of the melt body (e.g., the formation of

FeS+ -bearing spinel precipitates via the internal oxidation of an originally Fe 2÷-bearing aluminosilicate melt). One

can thus create fine-grained glass-ceramics from what would normally be non-glass-forming melts. Specific

research involves control reaction experiments on silicate glasses and levitated reaction experiments (aero-acoustic

and electrostatic levitation) on silicate melts.

2. Internal nucleation of inviscid pseudobina_ silicate melts via metastable liquid-phase immiscibili_.

Binary alkaline Earth oxide-silicate melts are highly exothermic. Nevertheless, the structural variations between

highly polymerized (silica-rich) and poorly polymerized (silica-poor) silicate liquids result in the creation of

composition zones (on the silica-rich end of the phase diagram) where a single silicate liquid is not stable. On the

silica-poor end of the diagram, this immiscibility would be metastable. As a consequence, if one can sufficiently

undercool an inviscid, silica-poor melt, one could perhaps cause metastable amorphous-phase separation to occur

prior to any crystallization. The phase separation could further promote the internal, fine (_un)-scale, uniform

nucleation and crystallization of the material. The creation of unique glass-ceramic materials becomes a possibility.

ScientiI]cally, measurements of heat evolution rate in such droplets will address questions concerning the role of

amorphous phase separation in crystalline nucleation.

TASK DESCRIPTION:

Two research approaches are employed for the two tasks:

1. Containerless processing for oxidation of Fe 2÷-bearing "alkaline Earth aluminosilicate melts via aero-acoustic

levitation (AAL). Small droplets (~Smm diameter) of ferrous iron-bearing calcium aluminosilicate glass, prepared

initially by bulk melting in a controlled-oxygen activity furnace, are levitated and remelted using AAL and laser

heating. The droplets thus formed are evaluated for their surface reactions, using Rutherlbrd backscattering

spectroscopy (RBS), and for their internal reactions using analytical transmission electron microscopy (AEM and

TEM). The kinetics of the redox reaction are evaluated as functions of temperature, time, and oxygen activity, the

latter controlled via the gas used as a levitation medium. The results of these experiments are compared to those

done at low temperature on glasses of identical composition; with such a check, the study can be later extended to

melts too inviscid to be glass tormers. The nature of nucleation as affected by local oxygen fugacity will be

explored using electron diffraction study of the internal oxidation front.

2. Drop-tube processing of pseudobinary silicate melts. Binary MgO-SiO2 metasilicate composiuons near the deep

cristobalite (SiO2)-enstatite (MgSiOs) eutectic are melted in a drop tube. Initially fine, crystalline powder, the fine

11-51 5
droplets are allowed by the degree of undercooling to experience metastable phase separation. Those droplets

receiving sufficient undercooling to additionally penetrate the glass transition can be thermodynamically analyzed to

explore the nature of nucleation in phase-separated amorphous materials. Primary analysis tools of the processing

include secondary electron emission microscopy (scanning electron microscope), X-ray diffraction, TEM and

electron microdiffraction, and differential thermal analysis and scanning calorimetry. These data should allow

discrimination of the role of amorphous-amorphous interlaces on crystalline nucleation in the phase-separated

amorphous droplets. The study will be extended to the binary ALO3-SiO__ system, the alumina-rich end producing

highly inviscid melts that, if sufficiently undercooled, could produce interesting aluminaJmullite glass-ceramics.

TASK SIGNIFICANCE:

Both of the specific tasks in this research are critically dependent on containerless processing: in both cases,

avoiding contmners eliminates the most blatant source of heterogeneity's that could promote heterogeneous

nucleation. In the case of redox reactions (Task 1) the contamerless requirement is additionally (and particularly)

important in that chemical (as opposed to structural, e.g., nucleation reactions can grossly affect the ionic-scale

dynamics and structure of a transition metal-bearing melt. For example, noble-metal crucibles (e.g. platinum) that

are often employed to contain refractory ionic melts will alloy with the transition metal ions incorporated in the

melt: chemical diffusion different from that desired in the redox experimental results.

Microgravity comes into play when working with inviscid ceramic melts, specifically in the same two manners

cited tor dealing with molten metals : (1) density contrast amongst phases and (2) the need for quiescence. Both of

these aspects are evident in our levitated melt drop experiments: melt viscosities of approxunately 1 Pa.s (10

Poises) allow for shear-force-induced convection (droplets are far too small for thermal convection at this viscosity;

processing of modestly larger melt bodies could promote thermal convection), which allows continuous exposure of

new melt to the outside atmosphere thus short-circuiting the desired chemical diffusion process; in droplets avoiding

convection, Ostwald ripening of internally formed ferrites allows them to sink to the bottom of the droplet, thus

removing them from positions to act as internal nuclei for silicate phases.

PROGRESSDURINGFY 1994:

1. Nucleation by internal

and melts.

oxidation or reduction of transition metal-bearing silicate glasses

Oxidation experiments were completed on a suite of CaO-Na_O-FeO-MgO-Al:O3-SiO2 glasses (prepared from

naturally occurring Columbia River Plateau Basalts) and on synthetic compositions minus Na:O. These

experiments were analyzed by Rutherford backscattering spectroscopy (RBS), optical microscopy, transmitted

electron microscopy (TEM) and high energy electron diffraction (HEED). The RBS spectra clearly indicate that the

oxidation process is accompanied by the flux of Ca:', Mg 2÷(both specimen types) and Na ÷ (natural basalt

specimens) to the tree surface with the subsequent formation of a two phase mixture of crystalline CaO and MgO

that partially covers the specimen surface. Beneath this surface layer lies a depleted silicate glass, that includes fine

precipitates of MgFe;O4 spinel. The morphology of the reaction is consistent with the oxidation occurring by

cation diffusion out of the glass. The kinetics are parabolic (diffusion limited); the rate-limiting step for the

oxidation/spinel nucleation process is thus diffusion of the divalent cations away from the reaction front towards the

free surface. The experiments have been successfully extended to melts in two ways. Spheres of both the natural

and synthetic compositions have been aero-acoustically levitated (AAL) and oxidized above the liquidus for the

original melt composition. In the spheres so levitated that remained quiescent, the internal oxidation/nucleation

process is plainly evident: internal homogeneous nucleation of magnesioferrite spinel (as well as Ostwald ripening

of these nuclei) and heterogeneous nucleation (on the spinel precipitates) of calcium -rich feldspar occurred. In

similar experiments employing electrostatic levitation (ESL), the synthetic specimens were successfully levitated.

Because of the limited capabilities of controlling the atmosphere in the ESL apparatus, a reduction reaction was

promoted thermally. The process results in nucleation of pyroxenes on the specimen surface (on Fe metal nuclei)

and an inward flux of metallic iron to so promote internal nucleation of silicates. Immediate future plans are to

finish the development of the kinetic models to describe these phenomena and to characterize, via TEM and HEED,

the crystalline nucleation process that occurs at the reaction front. Longer term plans are the transfer of the idea

from silicates to non-glass-lorming oxides.

1I-516
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

2. Internal nucleation of inviscid pseudobinary silicate melts via metastable liquid-phase

immiscibility.

MgO-SiO: binary melts (metasilicate composition) have been drop-tube processed at approximately 18(XYC. Yield

of these experiments was surprisingly extensive: approximately 80 vol.% of the fine (<50-_xrn particles experienced

melting in the process (a substantial increase in yield over powder processed at -1600°C). We are presently

collecting statistics on this processed powder, specifically discerning the amount of material that received sufficient

undercooling so as to remain amorphous. We are further pursuing thermal analysis experiments on the amorphous

powder to ascertmn, if possible, the role of amorphous phase separation on the nucleation of glass-ceramic (i.e.,

spatially unilbrmt fine-grained crystalline) microstructure in these droplets. Time resolved thermal analysis should

allow discrunination of surface nucleation processes (i.e., heterogeneous nucleation on amorphous-amorphous

interfaces) t_om possible homogeneous nucleation processes, as well as determine the scale of phase separation

important to promote appropriate crystallization. We anticipate collecting such dynamic data in the next few

months. Future plans include the extension of the work to a more inviscid system. AI20_- SiO2, which additionally

has significant economic value (i.e. mullite ceramics) with successful melt -processing to a glass-ceramic

microstructure.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 12/91 EXPIRATION: 11/94

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 963-26-07-01

MS Students: 0 MS Degrees: 2 RESPONSIBLECENTER: JPL

PhD Students: 1 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Cooper, R.F. "Internal nucleation by oxidation of an iron-doped Calcium-magnesium aluminosilicate melt." American

Ceramic Society, Indianapolis, IN, April, 1994.

Cooper, R.F. "Glass formation and nucleation in microgravity containerless-processed, inviscid silicate/oxide melts:

ground-based studies." MSAD Conference. Huntsville, AL, May 1994.

ini olie Ill I l UIll l aaoI I l Ill I I llllOI I I l It i el i Oil l I i i Ill I I l noi it i ill Ill Oil IS I Oill i Ol i i i iOi noi i Ol ill ill ill i i i i lOi I Ill Ill Oil el I l lllll l I I Ill l tl OI I OI OOl OIl nIoI oI l ol l Ul l I oI l i Il lI l i i i i i ol l nnnI oI l ol I Ii l I I l OI I I I l oiaI il l uaol aona* naoI I t t I I I tI aI I aI I aI I aot aoI

11-51 7
DirectionalSolidification in _He-4He Alloys

PRINCIPALINVESTIGATOR:Prof. Arnold Datun Case Western Reserve University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The goal of this research is to enhance our fundamental understanding of crystal growth kinetics, liquid-solid

interface morphologies, and the stability of alloys.

TASK DESCRIPTION:

A study ot' dendritic growth in two-dimensional samples of 4He is underway. Systematic studies of directional

solidification in 3He-4He alloys will be conducted to complement work that has been done in other alloys. Heat

conduction plays a minor role in this alloy at low _He concentrations, and the role of heat and particle transport can

be isolated.

TASK SIGNIFICANCE:

The study of morphologies is of intrinsic interest in testing theories of non-linear systems. Results which differ

from those of classical alloys will guide both theorists and experiments in their future studies, and significant

differences should result in new ideas for space-based alloy growth experiments. The studied 3He - 4He transparent

alloys have the advantage that they can be studied in a regime where the effects of concentration gradients can be

isolated from thermal gradients. That allows for a more complete understanding of the process of alloy

solidification and enhance the ability to design tailored materials (alloys with specific material properties).

PROGRESSDURING FY1994:

The goal of this research is to observe directional solidification in _He - 4He mixtures in the temperature range near

1.4 K where the melting curves for different concentrations of 3He cross. Directional solidification should occur

when the solute rich phase freezes at a higher pressure, i.e., fluctuations at the interlace leading to regions which are

rich in 3He will remain fluid, and the concentration in these regions will increase as the 3He isotope is expelled from

the advancing solid fingers around these regions. When the solute freezes at a lower pressure, regions which are rich

in 3He will freeze first, and _He will be expelled into regions of depleted 3He leading to a restoration of a fiat

interface. Thus, regimes where fingering does and does not occur should be separated by a small temperature

difference.

We have built an experimental apparatus for growing solid helium in a cell with visual access. A new technique for

sealing cells with large (2.5 x 5 cm) glass windows at 30 atm has been developed. The apparatus has undergone

numerous alterations as unforeseen problems have been solved.

In our experiment solidification is driven by a pressure differential at constant temperature. Solidification occurs at

pressures _ >__25atm. Our initial attempts to observe directional solidification led to some unforeseen difficulties.

Solid helium is not supposed to wet metals. However, on increasing the pressure, the solid phase grew from the

metallic sides of the cell instead of advancing from the horizontal solid-liquid interface in the cell. In addition, the

fill capillary would block when solid wet the walls of the capillary. We believe that these problems were associated

with the excellent heat conductivity of the metal. We have solved the problem of capillary blockage by insulating

the capillary from the cold helium. We have built a epoxy cell with a copper strip in the bottom so that the heat

cannot flow out of the sides of the cell. Recently, one of our cell exploded and broke our dewar. We are installing a

new dewar, and experimentation on directional solidification will resume soon.

_i_n_t_u_I_u_O_iQnu_Io_ou_I_1_iu_I_ou_D_D_u_o_u_It_i_n_u_n_i_H_nIn_unu_iu_unnin_u_I_I_*_ou_u_u_uu_u_u

I1-51 8
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

ii J|o H ol"_aHaH_uoI4_o_aiiaoo_aooaooiao_ao_aooo|o_nooaoo_"_"i"IHm"_HmHm"I_o"i"m_o_oI_"1o|a_aooao_aHa"Honaooua"loI_ua_"_aooao|_u_"a"_o_otoo .om.loonawoHH o alnltaouonao_la|a_|_oa.lnona.lo|laH;_|aul.laoltol.l|o

We have observed dendritic growth in two dimensions in pure _He. To our knowledge this is the llrst

two-dimensional dendrite experunent. The dendritic tips are of dimensions of 1 - 3 mm, while our cell thickness is

0.5 mm. Thus, heat flow is restricted to a plane, and the boun "dary conditions on equations describing

two-dimensional dendritic growth differ from the three-dimensional case. Control of the supersaturation temperature

is difficult in this case.

Our program is to I-trst study dendritic growth in two dimensions. This will not only be a new system Ior

investigation, but will give us experience for the directional solidification experiment. Next, we will undertake a

systematic study of directional solidification as a function of temperature and 3He concentration.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 1192 EXPIRATION: 12195

PROJECT IDENTIFICATION: 962-25-05-25

NASA CONTRACT NO.:NAG3-1412

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Chen, M.T. and Dahm, A.J. "Optical cell for observing solidificaion of helium". Cryogenics 34. (1994).

II-51 9
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

till lu i111 * i lll*l i oi aIll 01 Ill I lOUlOlnl I noI I olin* I oI oIl onI lnlilUO I uI I Igo Ill i aOl aIll Ollllllll Ill l uIIn aonalia l lllllllllllll*l*l ilUl n Ill i l 11 all I Ill lUlII I nil ill aIll l lllO I loll Ill l lllllll I lln IIIIIIU i lli llloO Ill I l 0lion Ion aonllinOilOlnlllllllllnlOO

Advanced Photonic Materials Produced by ContainerIess Processing

PRINCIPALINVESTIGATOR:Dr. Delbert E. Day University of Missouri, Rolla

CO-iNVESTIGATORS:

C.S. Ray University of Missouri, Rolla

TASK OBJECTIVE:

The objectives of this research were to 1) investigate non-linear optical glasses which have the potential for use as

ultra-last, all optical switches and other photonic devices for communication and advanced computer application, and

2) investigate and compare the kinetics of nucleation and crystallization for these glasses prepared by containerless

melting with the crystallization kinetics for the same glasses conventionally melted in a container.

Glasses with the potential for non-linear optical (NLO) applications such as the heavy metal oxide (HMO) glasses

containing PbO, Bi203 and Ga__O3are, in general, highly fluid and chemically corrosive. These melts readily

crystallize during cooling and develop unwanted color centers primarily due to impurities dissolved from the

container. The traditional procedures used to melt these glasses yield colored and chemically inhomogeneous

glasses of limited usefulness for NLO applications.

Containerless melting provides the opportunity to suppress or eliminate the undesirable heterogeneous nucleation

and crystallization in such melts. Since no container is used, color centers caused by impurities dissolved from a

container can be completely eliminated, even in highly corrosive melts. Containerless processing offers a viable

alternative for preparing glasses with improved purity and homogeneity, and NLO properties.

TASK DESCRIPTION:

Investigations of the NLO glasses are to be conducted with two HMO compositional systems: (l) PbO-Bi203-Ga203

and (2) compositions based on TeO2. The importance of the PbO-Bi203-Ga2.O3 glasses for NLO applications have

been demonstrated by scientists at Coming Inc., but these glasses had a color ranging from orange to yellow which

is believed to have come from impurities dissolved from the contmner. Attempts will be made to obtain colorless

PbO-Bi203-G_O3 glasses by changing the melting parameters that generally affect the color of a glass such as the

crucible material, melting temperature, time and atmosphere, and the starting raw materials. Containerless melting

technique will also be used to process these glasses so as to eliminate the color centers that are developed from the

impurities dissolved into melt from a container.

Like the PbO-BizO3-Ga203 glasses, the tellurite glasses also have a high refractive index (>1.9) along with a low

Abbe number (10 to 20), or high dispersion. Calculations using the empirical equation, n2= 391 (nd - 1)/Vd s/4which

was developed by Boling et al. (N. L. Boling, A. J. Glass and A. Owyoung, IEEE J. Quantum Electronics, QE-14,

601, 1978) and widely used by others, indicate that the tellurite glasses have a non-linear refractive index, n2, even

larger than that of the PbO-Bi203-G_O_ glasses (n o and V dare the usual linear refractive index and Abbe number,

respectively, for the glass with respect to sodium D-light). Also tellurite glasses have excellent optical

transmission (>85%) over a wide range, from 400 to 3500 nm. These make the tellurite glasses promising laser

hosts for a variety of rare earth ions, including Nd 3÷(primary laser wavelength 1060 nm).

The tellurite glasses for NLO applications will contain oxides of heavy metals such as Nb, Ta, Pb, and Bi to ensure

high density and refractive index (linear). Generally, glasses with a high refractive index also have a non-linear

refractive index (see the equation above). Minor addition of the oxides of Zn, Ga, Ca, AI and Ba in these glasses

will also be considered if needed to improve glass formation. The following work will be performed for both type

of HMO glasses.

_u_n_n_Du_u_n_u_n_n_nen_n_uu_u_nu_n_n_o_u_u_u_n_n_uun_n_w_n_n_j_I_1_

II-520
[I. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

.l,,.nn J_,l.n.lnan,,,,,,l,ll,ll,,,n | nl,,,,.,.ioln,. H.l,,,,.nnl. m.,,,,I.,.nsmHnlnnJ,,.i.l., nB,,,,.,n,,,,.,.,, n.,.,,¢llunnl,.n,,l,.,ll,.l,nl.,,nlu,n,nln,nnn,n, n,,¢,nn_,,,,llnnnl,,i.,.,o,,,._.

(1) Measure critical cooling rate of glass lormation, IL: (contmner), using the pen&ant drop technique (spherical glass

melt hanging from a thermocouple bead) to determine the glass forming lendency for these melts.

(2) Use contamerless melting techniques to prepare the glasses if Rc (container) for these glasses appear to be very.

high and/or contamination of the melts with the contmner melts is significant.

(3) Measure and compare R_ (contamerless) and Rc (container). The ratio of Re (contmner) to Rc (contamerless)

will be used to determine the improvement in glass Ionnation for containerless melts at l-g. The Rc (containerless)

will be measured at CRI, Inc., using their aero-acoustic levitator furnace.

(4) Measure selected properties such as the density, molar volume, linear refractive index and Abbe number,

chemical durability, thermal expansion coefficient, glass transition and crystallization temperatures, and the

transmission m the visible-ultraviolet and IR to determine the suitability of these glasses in practical applications.

(5) Calculate the non-linear refractive index, n2, Ibr each glass from the equation n2= 391(na - I)/V_ s'a an identify

those compositions best suited Ior NLO applications.

(6) Investigate and compare the kinetics of nucleation and crystallization for these glasses prepared by traditional

method and by contmnerless fashion.

(7) Measure XRD, IR and Raman spectra and evaluate the structure of these glasses.

TASK SIGNIFICANCE:

The following results are anticipated from this ground based investigation.

(1) The effect of different cations on the NLO properties of these glasses will be understood. This result will be

useful to developing glasses that have the NLO properties superior to those presently available.

(2) Comparing the properties for the glasses prepared by the traditional method with those for the glass prepared by

containerless melting, the need for processing these glasses in the microgravity environment of space for achieving

improved NLO properties will be known. However, the absence of gravity driven convection on the NLO

properties for these glasses will remain unknown. The results from several space-borne (low gravity) glass melting

experiments indicate that a glass prepared in microgravity is more resistant to crystallization and more chemically

homogeneous. The optical properties including the NLO and lasing efficiency for a glass processed in microgravity

are, therefore, expected to be improved compared to those for a glass at 1-g.

(3) The physical, thermal, optical, and spectroscopic properties for these HMO glasses that have the potential for

NLO and laser applications will be known for the first tune. The kinetics of nucleation and crystallization for these

glasses along with their tendency towards glass formation will also be known.

PROGRESSDu_n_ FY 1994:

A. PbO-Bi_O_-Ga20 _ Glasses

1. IR Spectra: To evaluate the structure of these PbO-Bi203-G_O 3glasses, the IR spectra from 400 to 3500 cm _

were measured for 14 glasses as a function of composition using the Kbr pellet technique. The IR spectra of these

glasses, generally have the same broad peak between 542 to 555 cm z which is identified as the vibration of Ga-O in

GaO4 groups. This result suggests that Ga 3÷ions act primarily as network forming cations in these glasses. When

Gae_O3exceeds about 30 mol%, a new peak at about 730 cm _ appears in the IR spectra, which is due to the vibration

of Ga-O in GaO_ groups. Thus, a part of the Ga _÷ions appear to be in 6-fold coordination when the Ga__O3content

exceeds 30 mol% in these glasses.

2. Raman Spectra: To further investigate the structure of these PbO-BizO_-Ga20_ glasses, it was planned to

measure the Raman spectra of the glasses and their devitrified products as a function of composition. These

measurements were undertaken by Dr. A. Biswas at JPL using samples provided by UMR. While these

II-521
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

_iI_i_ii_i_HiI_I_I_t|_H_i_|_¢i_ii¢_!_|ii|_1_t_ Jlliliollll,lllllallll|llll|, H tlllJltll J ltul|li|iilt olill Jll||ll|l.l.l.l|iil|llt ilillo|lotllotl!lloliloll61-11|llHItlll¢llt tltlHiiiilllltllilllllllll|l

measurements are presently continuing, measurements of Raman spectra for a 20PbO.60Bi0_ s.20GaO_s, cat%,

glass (HMO-1) and its crystallized products have been completed. The crystallization of the HMO-1 glass was

performed at 420 °, 480 °, 500 °, and 575°C for 1 h at each temperature. These data are now being analyzed, but the

preliminary results suggest the presence of Bi-O vibrational bonds, possibly in the BiO_ groups, in all the samples

crystallized at 420 °, 480°i and 500°C. The peaks corresponding to the vibration of Bi-O bond appeared in the

Raman spectra, most likely, for the crystallization of 2PbO.3Bi203 crystals. These crystals were identified by XRD

when this HMO-1 glass was crystallized at 420 °, 480 °, and 500°C. No peak corresponding to the vibration of Pb-O

appeared in the Raman spectra of these samples. The PbO bond in the 2PbO.3Bi,.O3 crystals is mostly ionic and,

hence, too weak to be detected by Raman measurements. New peaks corresponding to the vibration of Pb-O

appeared in the Raman spectra for the sample crystallized at 575°C. These Pb-O bonds are stronger and perhaps

more covalent like the bonds in the PbO4 groups present in PbO_ crystals. This result from the Raman spectra

cont-urms the XRD results obtained previously for the HMO-1 glass heat treated at 575°C for 1 h, where

2PbO:. 12Bi203 crystals were identified.

3. Nucleation Rate Curve: Except for the glasses containing a high amount of PbO (50-60, cat%), all the glasses

investigated in this PbO-Bi203-G_O3 system yield multiple DTA crystallization peaks, which makes it difficult to

determine either the activation energy for the crystallization peaks or the relative rates of nucleation at different

temperatures for these glasses. The activation energy for crystallization for a 60PbO.10Bi0, 530GaO_ 5, cat%

(HMO-12) glass, which contains a single DTA crystallization peak, was determined and was (470+/-15 kJ/moi).

The same HMO-12 glass was used to determine a nucleation rate type curve using the DTA technique developed by

ourselves (Ray and Day, J. Amer. Ceram. Soc. 73,439, 1990). In this technique, glass samples of constant weight

and particle size are first heated isothermally in the DTA furnace for a fixed time (nucleation), and then heated at a

constant rate until the glass crystallizes (crystallization). A plot of either the maxamum height of DTA

crystallization peak, (dTp) or the inverse temperature at the peak height maximum, 1/Tp, as a function of nucleation

temperature yields a curve similar to the well known nucleation rate vs. temperature curve found in many silicate

glasses. It was also shown that the dependence of dTp on nucleation temperature was more sensitive than that of

1/Tp.

When measured and plotted as a function of nucleation temperature, the dTp for this glass does not change from that

of the as quenched glass until the glass is nucleated above -265 °C, it then reaches a maxima at -343 °C and then

decreases to the value for the as-quenched glass at 375 °C. In other words, the temperature for nucleating this glass

ranges from -265 ° to 375 ° C and the temperature where the nucleating rate is a maximum, is 343 °C.

No information on the temperature range tor nucleation or the temperature for maxunum nucleation rate for this

glass is obtained from the plot of DTA peak temperature. In fact, Tp for a majority of glass samples nucleated at

different temperatures lies within the +/- 1.5°C limit of experimental error. Instead of yielding a bell-shaped curve,

Tp shows an increasing trend, although slightly, with increasing nucleating temperature, from -456 °C for the

as-quenched glass to -464 °C for the glass nucleated at 395 °C. The Tp for this HMO-12 glass measured after

different nucleation treatment is, theretbre, considered random and independent of the nucleation temperature

B. Tellurite Glasses:

Investigations on the formation, crystallization, and structure of binary Na:O-TeO2 glasses as a function of

composition have been started using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and IR

spectra. The objectives of this work are to gain a better understanding of (1) glass formation and crystallization

kinetics of tellurite melts and (2) the structural role of the Te -ions in these glasses. This knowledge will be useful

in developing and controlling the composition of TeO: containing glasses that have potential for non-linear optical

(NLO) and laser applications.

For DSC measurements, about 20 mg of glass powder composed of ~100 gln particles was sealed in an aluminum

pan, which was then heated at 10°C/min. in an atmosphere of flowing nitrogen until crystallizatxon was complete.

The DSC crystallization patterns for five glasses, with compositions Na20.2TeO_ (NTO, Na20.3TeO2 (NT3),

II-522
II. MSAD Program Tasks m Ground-based Research Discipline: Materials Science

i iiOOlOllollolllllullllaollualollol;ula4olHiislaellllllolllll J alJlI|01JII011HIIlaoalIIIHIIlUlI_IIHIOlIOH 1OlllllUln0111110110_ll ill m_|_t_"_n_H_in_au_I_|_4_i_H_|_o_"_no_j_

Na_O.4TeO, (NT4), Na20.5TeO: CNTs), and N_O.6TeO: (NT_) have been measured to date. With the excepuon of

the NT_ glass, all the other glasses exhibit multiple crystallization peaks, indicating crystallization of two or more

phases. The onset temperature for crystallization is highest for NT4 glass indicating this glass is most stable of

those measured. The activation energy Ior crystallization and a nucleation rate type curve for this NT4 glass are now

being measured using DSC. Sodium tellurite glasses were crystallized at their respective maxunum temperatures

(obtained from DSC) for 24 h and analyzed by XRD. The crystalline phase(s) lormed in each glass are in accordance

with the phase diagram for this binary Na20-TeO: system, with the exception that in the devitrified NT_ glass both

NT4 and NT2 crystals should be present according to the phase diagram, while only NT4 crystals were identified m

this sample. A comparison of the number of crystalline phases identified by XRD (only 1 or 2 lot all the

compositions) with the multiple crystallization peaks exhibited by DSC suggests that these glasses undergo a series

of phase transformations during heating.

The IR spectra for these sodium tellurite glasses and their devitrified counterparts have been measured using the KBr

pellet technique. Preliminary analysis show that the structure of the NT4 glass contains primarily [TeO_l

bipyrarmdal groups, while the structure of all the other glasses of higher or lower TeO: content than the NT_ glass,

contain both [TeO3] pyramidal and [TeO4] bipyramidal groups. Further analysis of the IR spectra for these glasses

is continuing.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 12/91 EXPIRATION: 11/94

PROJECT IDENTIFICATION: 963-26-07-02

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Huang, W.. C. S. Ray, and D. E. Day. Heavy metal oxide glass part 1: Structural aspect and crystallization behavior. Glass

& Enamel (in Chinese), 21, [4], 1-8 (1993).

Huang, W.. C. S. Ray, and D. E. Day. Heavy metal oxide glass Part 2: structural aspect and crystallization behavior. Glass

& Enamel (in Chinese), 21. [6], 1-12 (1993).

Ray, C.S. and D. E. Day. Nucleation and crystallization in glasses as determined by DTA. Ceramic Transactions. 30.

207-223 (1993).

Ray, C.S. and D. E. Day. Identifying internal and surface crystallization by differential thermal analysis for the glass to

crystal transformations. Thermochim. Acta, (In Press).

Ray. C.S., W. Huang, and D. E. Day. Nucleation, crystallization and structure of PbO-BiO, _-GaO_ _ glasses. J. Am. Ceram.

Soc. (in press).

Huang, W., Ray, C.S., and Day, D.E. Color and selected properties of PbO-BiO, : -GaO_ _ glasses. J. Am. Ceram. Soc. 77.

1017--24 (1994).

Proceedings

Ray, C.S., Makihara. M.. Hayakawa, J., and Day, D.E. "Evaporation of a sodium tellurite melt in the JAMIC Low Gravity

Drop Shaft." Proceedings of the 19th International Symposium on Space Technology arid Science, Yokohama, Japan,

May 15-24 (1994).

Presentations

Ray, C.S. and Day. D.E. "Advanced photonic materials produced by containerless processing." Presented at the MSAD

Division Microgravity Program review at Huntsville. AL, 24-25 May, 1994.

Ol i no i iii ill i Ollllllll i ii i Illlllll Ill I Ill nil aoil OI I III Ill a000Oil OOllOlllllOl II I l Unil I on i Ol I IIIOOIIIIIIIIIIOlUIUIIIOlIIIIIIIIIIION I U I Oil Ill IHill I nl I I I I oOl Il UIII IIi Ill uiii i ill Ill OI I I l UaIll nl I if i i i ui olnlll 1111.nulnllnll i i i i i i i i i iiion|ll|ll|ln

11-523
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

The Effect of Gravity on Natural Convection and Crystal Growth

PRINCIPALINVESTIGATOR: Dr. Graham D. de Vahl Davis University of New South Wales

CO-INVESTIGATORS:

H.C. deGroh III NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

1. To experimentally measure natural convection during Bridgman growth at varying gravity-driven levels and to

quantitatively determine how this convection aflects parameters of critical importance to the crystal grower such as

interface shape, and radial and longitudinal segregation.

2. To produce an accessible, experimentally verified numerical code capable of accurately determining levels of

convection in real systems at varying gravity levels and directions, and the effects of this convection on the

solidification process.

3. To supply and supplement numerical modeling efforts lor the MEPHISTO II flight experiment of Dr. R.

Abbaschian.

TASK DESCRIPTION:

The major goal of many space experiments in solidification is to determine how convection influences various

phenomena such as undercooling at the solid/liquid interlace, redistribution of solute, and crystal quality. However,

in most flight experiments, as in the MEPHISTO experim ,_ which are being done using an opaque alloy of

Bi-Sn, no measurements of convection are possible. Expe_ ments and numerical studies are being done to estimate

convection and its effects. Two codes are under development: 1. A modified version of the commercial finite

element code FIDAP (due to M. Yao), and 2. A finite difference code (due to G. de Vahl Davis, E. Leonardi and

students). Both may be available to investigators. In our experiments, we are using the transparent metal analog

succinonitrile, which allows direct analysis of convection and interface shape.

TASK SIGNIFICANCE:

Our research will yield expertmentally verified codes capable of calculating amounts of convection present in the

melt at 1-g horizontal, vertical, and various intermediate angles, and in Iow-g with various residual gravity values,

angles and frequencies. Thus it is hoped that current flight experiments, as well as future flight experiments, will

benefit from this research. The models will complement the scaling, analytical modeling and parametric

experimental studies of others (Coriell, Favier, Thevenard and Camel) and will be used to check the validity,

extension and generalization of scaling laws.

PROGRESSDURING FY 1994:

Solidification Experiments: Experimental studies of succinonitrile during solidification, melting and no-growth

conditions using a horizontal Bridgman furnace and square glass ampoules have been conducted. For use as input

boundary conditions to the numerical codes, thermal prot-des inside and on the outside of the ampoule were

measured. The shapes of the s/l interlace in various 2-D planes were quantitatively determined. Though interlaces

were non-dendritic and non-cellular, they were not "flat," but were highly curved and symmetric in the vertical,

longitudinal plane. The shape of the interfaces were dominated by the primary longitudinal flow cell characteristic

of shallow cavity flow in horizontal Bridgman; this flow cell was driven by the imposed furnace temperature

gradient and caused a "radial" thermal gradient such that the upper half of the ampoule was hotter than the bottom

hall. These data will be used to examine the numerical models. Presently underway is an effort to measure fluid

flow velocities and interface shape and convective modes at various ampoule angles between vertical and horizontal.

_=t_|_||=|_||_!|_!_I_||_!_o|_|_|_|_I_!_!_|_||_|_||_!_!_||o|||||_|_e_|_|_!|_o_e|_|_||_|_|_|_I_!_!!|!_|_!_o_!_=_e_|_I!_|_!_|_t_I_!_o

11-52,4
IL MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

i iil.l.iHtllnMl|nltll f lll|lUVOIIIl|lllHIllll!l.lllll.l|ll.llllllllH n_"_nI_II_!_1_nn_1_1_1_1_"n_H_1_"_1_I|_lI_non_H_el_n HI lUlnnlllllllllllUllllllnlllllUlllllllnUlltlll.lllltnnlllnlnnlll

Numeric;fl M(xleling: The results of the numerical codes have been compared to the experiments in succinonitrile

and excellent agreement ha.s been achieved. The codes have been u_d to predict interlace shape, thermal fields and

fluid flow velocities during horizontal Bridgman no-growth, and solidification conditions in 2-D and 3-D. The

segregated solution approach has enabled free mesh 3-D solidification simulations, using FIDAP, to be run on a

work station. The front tracking technique and solute concentration have been incorporated into the finite element

model. In contr&st to the lormerly used enthalpy-type method, the front tracking technique involves a deforming

spatial grid and is able to model phase changes with sharp interfaces. These new efforLs have greatly enhanced the

capability of our numerical simulations. Using the front tracking method, a 2-D simulation of the capability of our

numerical simulations. Using the front tracking method, a 2-D simulation of the MEPHISTO II vertical 1-g and

space expertments has been done: it was found at g<104 earth gravity, solidification was diffusion controlled. 3-D

finite difference solution methods using body-tilted coordinates have allowed ml accurate representation of the

interface shape, position and growth to be obtained, together with detailed results for the flow pattern and

temperature distribution. Other low-g stmulations are underway and future efforts will include non-steady gravities

(g:jitter) and with g at various angles to the ampoule axis, as is expected in space.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 11/92 EXPIRATION: 10/95

BS Students: 0 PROJECT IDENTIFICATION: 962-21-05-09

MS Students: I RESPONSIBLE CENTER: LeRC

PhD Students: I

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Yao, M. and deGroh III, H.C. Segregated solution m 3-d modeling of crystal growth. NASA Tech Brief, vol. 17, no. 11,

(1993).

Yao, M. and deGroh HI, H.C. Three-dimensional finite element method simulation of bridgman crystal growth and

comparison with experiments. Numerical Heat Transfer, vol. 24, 393-412 (1993).

NASA Tech Briefs

de Groth, III, H.C. and Lindstrom. Tiffant. Interface shape and convection during melting and solidificalion of

succintmitrilc. NASA Tech Brief. 107724, (1994).

I'ruceedings

de Groh Ill. H.C. and Nelson, E.S. "On residual acceleration during space experiments." Heat Transfer in Microgravity

,qyslems, edited by S.S. Sadhal and A. Gopinathi, HTD - Vol.290, ASME, 1994. pp. 23-33.

tie Groh IlL H.C. and Yao, M. "Numerical and experimental study of transport phenomena in directional solidification of

succmonitrile." Transport Phenomena in Solidification. edited by C. Beckermann et al., HTD-Vol. 284, AMD-Vot. 182.

1994 ASME. pp. 227 243.

de Vahl Davis, Graham and de Groth, H.C. "The effect of gravity on naturM convection and crystal growth." Proceeding of

the Microgravity Materials Science Conference, huntsville, Alabama. May. 1994.

Yet)h. G.H.. de Vahl Davis. E., Leonardi, E,. de Groh III. H.C, and Yao, M. "A numerical and experimental study of natural

convection and interface shape in crystal growth." in proceeding of the First International Conference on Transport

Phenomena in Processing, S.I. Guceri editor, 1993, pp.98-109.

' 'nil Ill Ill Illl Ill l lllllnOUllllllOllOlllll I lOl In I Ill ash Hill mill all 1011011 n llOllOllllllOllllllllOlOIIOnlOllOllOllOlllllln nIll OllOUtllllllllIlU lIl nIIIOllOa IllOlla Ill llllll no11011 Ill loll Ill I11 Ut01011 ill ii ii Hill i ill i ii nOi i i aii inn anOaOil I I lUll

II-525
Use of Synchrotron White Beam X-ray Topography for the Characterization of the Microstructural

Development of Crystal - Normal Gravity Versus Microgravity

PRINCIPAL INVESTIGATOR:Dr. Michael Dudley State University of New York, Stony Brook

CO-INVESTIGATORS:

D. Larson Northrop-Grumman

TASK OBJECTIVE:

The objective of the research proposed here is to provide an assessment of the influence of the accelerated cooling

rates, imposed by severe limitations on available llight time, on the defect microstructure of crystals grown in a

microgravity environment (using, for example, modified Bridgman or Vapor Transport techniques). Results

previously obtained on ground based ZnTe samples (grown by Vapor Transport at NASA Marshall Space Flight

Center) seem to indicate that if cooling rates are too high the accentuated thermal mismatch stresses can give rise to

deformation processes, comprising the formation of dislocation slip bands.

The objective of the present research is to extend the preliminary work on ground based samples, to furl.her ground

based samples and also to flight samples grown with different cooling rates. The nucrostructures of the as-grown

crystals will be non-destructively characterized using the technique of Synchrotron White Beam X-ray Topography

(SWBXT). Correlations between the existence of significant post-growth deformation and accelerated growth rates

will be direcdy examined.

The influence of accelerated cooling rates on the significance of the comparison drawn between normal gravity and

microgravity crystal growth can thus be determined.

TASK DESCRIPTION:

The research proposed here will be carried out using Synchrotron White Beam X-ray Topography (SWBXT) at the

Stony Brook Synchrotron Topography Facility, with is under the direction of Prof. Dudley. It will consist of

SWBXT characterization of crystals grown in a microgravity environment primarily obtained from co-investigator

Dr. D.J. Larson, Jr., of Grumman Corporate Research Center, as well as from other sources such as Drs. D.

Gillies, and C. Su at NASA Marshall Space Flight Center. Crystals of CdZnTe and ZnTe will be examined,

"although many other systems of interest to NASA are expected to be studied, for example ZnSe, CdTe, HgCdTe and

PbSnSe. Opportunities will be sought amongst the NASA crystal growth community to maximize the amount of

data obtained on as many different systems as possible. Crystals grown at various cooling rates will be examined,

and the influence of these rates on the resulting microstructure will be assessed.

In the approach adopted hem, reflection topographs from the cylindrical outside surface of the as-grown boules will

be initially examined. These will provide information on the defect structures in the region from the outside surface

down to the penetration depth of the X-ray beam, which is typically 5-10 m. This enables an overall assessment of

the distribution of defects such as twins, sub-grain and grain boundaries, and dislocations to be made. This can aid

in the development of optimal watering geometries to enable clearest visualization of the defect microstructure.

Following this, both reflection and transmission topographs will be recorded from the individual waters. Images

obtained from the various wafers will be compared with those obtained from the original boules, and an overall

representation of the three dimensional distribution of defects throughout the boule will thus be developed. B y

comparing such three dimensional representations of defects in crystals grown with various cooling rates, the

influence of the cooling rate on the type and distribution of defects in the crystals can be determined.

It is anticipated that results may indicate that accelerated cooling rates, dictated by schedule limitations, have a

dominant effect on the microstructure of crystals grown in a microgravity environment, thus obscuring inlormation

il-526
on the influence of the magnitude of the gravity vector. It is further anticipated that these results may lead to a

change in the criteria used to determine time allocation for individual crystal growth experiments on future flights in

order to avoid effect,s on crystal microstructure resulting from effects unrelated to the magnitude of the gravity

vector.

TASK SIGNIFICANCE:

Much effort has been, and continues to be expended by NASA in evaluating the influence of a microgravity

environment on the defect microstructures developed in crystals during crystal growth. While the influence of a

microgravity environment on crystal growth is generally accepted as being beneficial, it is not clear that prior

studies of this influence have been unperturbed by artifacts related to the particular choice of experimental

conditions. Indeed, in order to properly compare crystal growth in a microgravity environment to that in a normal

gravity environment it is important to be able to isolate the influence exerted by the difference in magnitude of the

gravity vector on the resultant crystal quality. Effects associated with accelerated cooling rates, or sudden changes in

temperature gradient, imposed either deliberately or inadvertently, detract from the significance of such experiments.

Results already obtained from ZnTe crystals grown in a normal gravity environment seem to indicate that stresses

generated by thermal mismatch effects during cooling can significantly affect the observed, as-grown defect

microstructure. These stresses lead to the formation of dislocation slip bands which tend to obscure and/or break up

the true growth defect microstructure. Should such effects occur in crystals grown in a microgravity environment,

the true influence of microgravity on crystal quality cannot be assessed.

It is thus of paramount importance to be able to assess the effect of the accelerated cooling rates, dictated by flight

schedule limitations, on resulting defect microstructures. One can gain insight into the chronological history of the

development of the final defect microstructure from analysis of images recorded using Synchrotron White beam

X-ray Topography (SWBXT). This is a non-destructive imaging diffraction technique capable of revealing the

detailed defect microstructure in large single crystals. Such defect microstructures in crystals grown with various

cooling rates will be compared and examined for evidence of extensive, post-growth slip. Maximum usable cooling

rates can thus be determined.

Determination ol the influence of cooling rate on the defect microstructure of crystals is crucial for selection of

expertmental conditions under which the effects of the gravity vector on crystal growth quality can be usefully

investigated. Once such selection has been optimized, differences in microstructure observed in microgravity grown

crystals may be sa.tely attributed to the influence of the gravity vector, and not to artifacts related to compressed

growth schedules.

Should accelerated cooling rates be shown to have a detrimental effect on defect microstructures in microgravity

grown crystals, it is likely that this result could modify the criteria used to determine the experimental schedules for

microgravity crystal growth.

PROGRESSDURINGFY 1994:

Significant progress has already been made on this project. Professor Dudley, Dr. Larson, and Graduate student Hua

Chang have been systematically recording topographs from several wafers cut from three boules: one ground based

CdZnTe sample and two flight samples (numbered 1 and 2), all grown by Dr. D.J. Larson, Jr. (the latter two on

USML-1). These crystals were originally examined in boule form using reflection topography. This revealed the

overall distribution of defects in the outer cylindrical surface of the boule down to a depth of around 5-10

micrometers. Twins and slip bands were readily revealed. Twins appeared to nucleate at regions of partial wall

contact. Further studies of the effects of cooling rate on microstructure are envisaged in as-grown boules, prior to

cutting. As in the case presented below this will be followed up with studies of as-cut waters. The ability to

investigate boules, as-grown, before cutting, means that one can be sure that one is observing the true

microstructure developed during the growth process, with no possibility for artifacts, for example due to polishing

or cutti_e, to exist. In addition, if effects due to thermal mismatch associated with rapid cooling are of interest,

these are likely to give rise to deformation microstructures which would be concentrated near the periphery of the

boule, which is precisely the volume examined in these experiments.

11-527
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

i:Jall|llsnnllnl|lgl:lslll|lmlll|lllllllllllllltlnlllelllollIDl|ll!t llollello!ollol|llt |l*.onllallal|al|ll:l!|.|ll| jl|_lI_ge|_ii_ml_IiI_||_g_n_j|iii!n|_el_||!ao_I_!aDo||II|n_Inn|ii||_|||i|_iI_Il:i_oH||_||_|||||_||_|_!_!_*_||nn|_|*!

Topographic images recorded from wafers sliced from the ground-based sample showed slip bands and a relatively

high dislocation density (in excess of 105cm-2). Examination of waters cut from the most slowly cooled region of

flight sample number 2 reveals very low dislocation density regions (less than 102cm-2) with individual

dislocations being easily resolvable. A low density of precipitates is 'also clearly observed. Images recorded from a

more rapidly cooled region of the same sample shows higher dislocauon density (approaching 104cm-2).

Tolx)graphs recorded from a water sliced from flight sample number 1 which was more rapidly cooled than flight

sample number 2 reveal a significantly higher overall dislocation density (approaching 105cm-2) and also the

existence of extensive slip which is observable throughout the imaged volume. These results contLrm the initial

hypothesis that accelerated cooling rates, imposed by compressed flight schedules, could potentially obscure and/or

destroy the underlying actual growth defect structure, hindering the assessment of the influence of gravity vector

magnitude on crystal quality. In general it appears that increasing cooling rate first increases the overall growth

dislocation density, and then produces slip which obscures this growth defect structure. Further detailed work is

underway to examine more wafers from these boules, and from other boules, in order to further examine this

correlation between the observed three-dimensional defect structure and the local cooling rate.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-21-08-27

MS Students: 0 NASA CONTRACTNO.: NCC8-48

PhD Students: 1 RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Casagrande, L.G., Larson. D.J., DiMarzio. D., Wu, J., and Dudley, M. The growth and camparison of large-diameter,

vertical Bridgman CdZnTe and CdTe. J. Cryst. Growth, vol. 137. 195-200 (1994).

Fanning, T., Dudley, M.. and Lee. M.B. Synchrotron white beam X-ray topography study of dislocation propagation from

inclusions in CdTe(111)B. 1993 National Synchrotron Light Source Activity Report, B-162 (1994).

Zhou, W,, Dudley, M., Su. C.H., Gillies, D.C, Szofran, F.R., and Lechoczky, S.L. ColrreLations between growth defects

and growth conditions in ZnTe single crystals. 1993 National Synchrotron Light Source Activity Report, B-175 (1994).

Zhou, W.. Dudley, M., Su. C.H.. Gillies, D.C., Szofran. F.R.. and Lehoczky. S.L. Atomic structures of twin boundaries in

ZnTe single crystals. 1993 Natioanl Synchrotron Light Source Activity Report. B-174 (1994).

Zhou, W.. Dudley, M., Su, C.H., Gillies, D.C., Szofran, F.R, and Lehoczky, S.L. Synchrotron white beam reflection

topography of interfaces in gallium-doped germanium. 1993 National Synchrotron Light Source Activity Report, B-174

(1994).

Zhou, W., Dudley, M, Su. C.H., Volz, M.P., Gillies, D., Szofran, F.R., and Lehoczky, S.L. Synchrotron topography

characterization of ZnTe single crystal. Mater. Sci. & Engin., vol. B27, 143-153 (1994).

Proceedings

Casagrande, L.G., Larson, D.J., DiMarzio, D., Wu, J., and Dudley, M. "Growth of large-area, high quality CdZnTe

substxates by the computer controlled vertical Bridgman method." Productibility of II-IV Materials and Devices, H.K.

Pollehn and R. Balcerak. eds., SPIE Proc., 2228, 21-32 (1994).

DiMarzio. D., Larson, D.J., Casagrande, L.G., Wu. J., Dudley, M., Tobin. S., and Norton, P. "Large area X-ray

topographic screening of II-VI substrates and epilayers." Producibility of II-VI Materials and Devices, H.K. Pollehn and R.

Balcerak, eds.. SPIE Proc.. 2228, 289-300 (1994).

Dudley, M. "X-ray topography." Applications of Synchrotron Radiation Techniques to Materials Science, D.L. Perry, R.

Stockbauer, N. Shinn, K. D'Amico, and L. Terminello, eds., Mat. Res. Soc. Symp. Proc., 307, 213-224 (1993).

11-528
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

n o i i o i io i I o i n o i n a n n n n a o! i o a i o i i o o I no i io n i | n i o | i o o i ao I iI n i I i I I i i i i n n o o nJoBn o i i o i i o o i | o i no I i a i n o o u o i iI i i o i ill ! o I! o i! o I o o | i o o i o o 11ii ! ii o o i I o | i o !! o o o a o i ! o |a | o o oo o o o o o o i i o i oo ! o uo Io o I o I o o a olu * i an Io o I o I o I | * iii o o ! o i I oI I o I I I o I I o i o u I ii o i a so i ell o n ao I| o I Io

Dudley, M.. Wu, J.. Larson. D.J.. and DiMarzio. D. "Use of white beam X-ray topography to characterize IR detector

manufacturing processes." Diagnostic Techniques for Semiconductor Materials Processing, O.J. Glembocki, F.H. Pollak,

S.W. Pang, G. Larrabee. and G.M. Crean. eds., Mat. Res. Soc. Syrup. Proc.. 324. 457-462 (1994).

Larson, D.J., DiMarzio, D.. Casagrande. L.G., Carlson, F.M.. Lee, T., Steiner, B., Long, G.. Seiler, D.G.. Wu, J., and

Dudley, M. "Producibility improvements suggested by a validated process model of seeded CdZnTe vertical Bridgman

growth." Productibility of I]-VI Materials and Devices, H.K. Pollehn and R. Balcerak. eds., SPTE Proc., 2228, 11-20

(1994)

Su. C.H., Sha. Y.G., Volz, M.P.. Gillies. D.C.. Szofran, F.R., Lehoczky. S.L.. Zhou, W.. Dudley, M., Liu, H.C..Brebrick.

R.F., and Wang, J.C. "Ground-based research of crystal growth II-VI compound semiconductors by physical vapor

transport." Proceedings of the 32nd AIAA Aerospace Sciences Meeting. paper no. AIAA 94-0564 (1994).

Zhou, W.. Dudley, M., Su, C.H., Volz. M.P., Gillies. D., Szofran. F.R., and Lehoczky, S.L. "Characterization of growth

defects in ZnTe single crystals." Infrared Detectors - Materials, Processing, and Devices. A. Applebaum and L.R. Dawson.

eds., Mat. Res. Soc. Symp. Proc., 299, 203-208 (1994).

Books

Dudley, M. "Characterization by X-ray Topography" in "Encyclopedia of Advanced Materials." Edited by: D. Bloor, R. J.

Brook. M.C. Flemings, and S. Mahajan Pergamon. vol. 4. pp 2950-2956, 1994.

Presentations

Casagrande, L.G., Larson, D.J., DiMarzio. D., Wu, J.. and Dudley, M. "Growth of large-area, high quality CdZnTe

substrates by the computer controlled vertical bridgman method." SPIE Meeting on Producibility of II-VI Materials and

Devices, Orlando. FL, April 5-8. 1994.

DiMarzio, D.. Larson. D.J., Casagrande, L.G., Wu, J., Dudley. M., Tobin. S., and Norton. P. "Large area X-ray

topographic screening of II-VI substrates and epilayers." SPIE Meeting on Producibility of II-VI Materials and Devices,

Orlando, FL, April 5-8, 1994.

Dudley, M. "White beam synchrotron topography of U-VI crystals." Invited lecture at Loral Infrared and Imaging

Systems, Lexington, MA, December 2. 1993.

Dudley, M. "Synchrotron white beam X-ray topography of II-VI crystals." Invited lecture at Santa Barbara Research

Center. Santa Barbara. CA. April 6. 1994.

Dudley, M., Wu. J., Fanning, T., Larson. D.J., DiMaxzio, D.. and Lee, M.B. "Use of white beam X-ray topography to

characterize IR detector manufacturing processes." Poster presented at the Fall 1993 MRS Meeting Symposium on

Diagnostic Techniques for Semiconductor Materials Processing, Boston. MA, November 29-December 2. 1993.

Larson, D.J., DiMarzio, D., Casagrande, L.G., Carlson, F.M., Lee, T., Steiner, B., Long, G., Seiler, D.G.. Wu, J.. and

Dudley, M. "Producibility improvements suggested by a validated process model of seeded CdZnTe vertical Bridgman

growth." SPIE Meeting on Producibility of II-VI Materials and Devices. Orlando, FL, April 5-8. 1994.

aaooouI * uo* oIs 1nnI ao I aoi uoI aI ouennoi ni nuei ! II ai i i i nuenaI nooo! ooi ni i aI oaooaoI ooeoaeul oIn el neI I ouneI noI oo; ooooI eel ell leo ell el Oin i ou! oI! eI I oleo oI I oleo Ill oI I I ouI ooI oaeel oIll oouell o ooI e lie I In oon I oaelos ill nooeoIllas lie I as, Ill I OeI USIn * l aOIn elas Oas uI nOaio

11-529
IL MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

I i iI | I! | n n o I I | | I I e DI I |! 14 I| 6 IIe I! o I I| I I I | u | |l | |1 t I! |I I | DI ! I i III I| I| I i n _ I I | OI i | I gi I I* I I o | i | | II | Io I I | | i ! | I I e DI I | |I I I! I ! ! 411 _ | Ie |i | | t g i n | o i i | | i i |! mi i ! | i ! i i ! i i! o i i t i i J i i I I i | !I | i i i QI I | i ! o | ! ii _ i i i iii I I i iii i |! i ! iii | e _ | | i ! | Ii ! Qo | | mi I i | i i| i i | i ! | i ! | i | | i

Reverse Micelle Based Synthesis of Microporous Materials in Microgravity

PRINCIPALINVESTIGATOR: Prof. Prabir K. Dutta Ohio State University

CO-INVESTIGATORS:

Dr. C.T. Kresge

Dr. R. Ansari

W. Meyer

Mobil Research & Development Corporation

NASA Lewis Research Center (LeRC)

NASA Lewis Research Center fLeRC)

TASK OBJECTIVE:

The objective of this research is to better understand the synthesis of microporous materials, especially those based

on a network of connecting substructures. Examples of microprobes materials include silico-aluminates widely

used as catalysts and absorbents and natural bio-materials such as bone.

TASK DESCRIPTION:

The synthesis of zincophosphate microporous material is studied via the novel synthesis route of reverse micelles.

The reverse micelles isolate small portions of reactant and allow examination of different fabrication routes

emphasizing single layer additive growth, agglomeration of subsize particles and reconstruction from a gel-like

mass.

The different paths are studied to determine the influence of convective flows and Stokes settling. Conditions for

zincophosphate growth appropriate for on orbit experimentation are identified.

TASK SIGNIFICANCE:

Microporous materials have extremely wide application as catalysts and absorbents. Their complex structure is

derived from chemical and physical transformations which have to date eluded investigators. This research separates

portions of the nucleation and growth process/or examinations. It may lead to greater understanding of how these

materials form, to new synthesis routes, to new materials and thereby to changes economics of petroleum

processing.

PROGRESSDURING FY 1994:

Three paths for zincophosphate crystal growth have been identified. These paths involve benign using reverse

micelles procedures appropriate for performance on orbit. It has been shown by tests using rotating cells that the

synthesis is sensitive to Stokes settling. It has also been shown that laser light scattering tracks particle growth at

sizes larger than the predominant micelles size.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/95

BS Students: 0 PROJECT IDENTIFICATION: 963-26-05-01

MS Students: 0 NASA CONTRACT NO.:NAG3-1416

PhD Students: 1 RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONSFORFY 1994:

Journals

Dutta, P.K., Jakupca, M., Salvati. L., Reddy, K.S.N.. and Ansari, R.R. Reverse micelle based synthesis of microporous

materials in hydrocarbon solvents. Studies in Surface Science and Catalysts, vol. 84, 235 (1994).

Presentations

Dutta, P.K.. Jakupca, M., Salvati. L., Reddy, K.S,N., and Ansari, R.R. "Synthesis of microporous materials in reverse

micelles." AIAA 94-0569, 32nd Aerospace Meeting, Reno. NV, 1994.
Growth of Nonlinear Optical Thin Fihns and Single Crystals by Vapor Processes

PRINCIPALINVESTIGATOR:Dr. Donald O. Frazier NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

B. Penn NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

A major goal of this program is to study the dynamics of physical vapor transport for the growth of high-quality

thin films and single crystals of nonlinear optical (NLO) organic and polymeric materials. The program involves

the experiment and modeling of heat and mass transport during vapor deposition of materials of interest, and

subsequent coupling with film formation kinetics, and application to bulk crystal growth.

TASK DESCRIPTION:

This work now focuses on specific materials of interest for study. Initially, the program involved the screening and

tailoring of many possible derivatives, and included synthesis, purification, processing, and characterization to

determine the best possible NLO organic and polymeric materials for microgravity study. The work now focuses

on vapor deposition of a 2-methyl -4-nitroaniline IMNA) diacetylene derivative on various substrates, and

subsequent solid-state photopolymerization to the corresponding polydiacetylene. Also, the work continues the

microgravity experiment to deposit phthalocyanine films (porphyrins, generally), by 3M Corporation, which were

dramatically different from Earth-processed thin films. Both of these materials have excellent third-order NLO

properties, but detailed information on the gravitational effect on film formation by physical vapor transport is

absent. This work studies coupling between heat and mass transport and film/crystal morphologies.

Research Approach - The approach is to prepare thin films of diacetylene monomers and photopolymerize the

monomer deposits on various substrates. Deposition of metal-free phthalocyanines "also yields films of excellent

third-order nonlinearity ('also, good second harmonic generation (SHG) is possible). Metal-free phthalocyanines also

provide appropriately oriented substrates for deposition of metaJ phthalocyanines which could enhance electron

mobilities and polarizabilities. These expenment,s are in progress with plans for future microgravity processing to

study enhancement of orientation, and modeling of the physical vapor transport process. Fabrication of a horizontal

furnace is complete, and physical vapor transport of 4-N,N'-dimethylamino-4" -N-methylstilbazolium tosylate

(DAST) will proceed by seeking coupling between heat and mass transport and growth kinetics. DAST, because of

the ionic nature of its crystal packings (a salt), could provide the basis for improving the mechanical strength of

organics having very high SHG efficiencies.

TASK SIGNIFICANCE:

Many of the crystal/film growth processes appropriate for inorganic crystal growth and which amplify key elements

of microgravity materials processing are equally applicable to the growth of organic photonic materials. Indeed,

there is an opportunity to observe the effects of fundamental microgravity related phenomena not possible to study

in semiconductors. Furthermore. these materials may comprise a large share of the next generation of materials for

computer applications.

PROGRESSDURINGFY 1994:

This work has "advanced from screening and tailoring of many possible derivatives, to vapor deposition of a

2-methyl -4-nitroaniline (MNA) diacetylene derivative on various substrates, and subsequent solid-state

photopolymerization to the corresoponding polydiacetylene. Additional focus is on the incomplete microgravity

experiment to deposit phthalocyanine films (porphyrins, generally), by 3M Corporation, which were dramatically

different from Earth-processed thin films. We plan to complete this work by modeling the heat and mass transport,

11-531
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

,i |, | I,, _, t |, 4, !. |, e, | _,, i |! ooI oI t I I _I. | i, i |. |, i. i;,, I I I J _m, I!. |, i; ! I,,, 6,, * I i, | I g, I ,, ||. I, I I |e It eIII Ill |, o| o| | ,i, oi i oi| ! i ! I _* I I, ! !, ! J i, 11o! i | | i ! * i t, |. ! |l i, 11 * i! I I I e; I, !, ! st, i |l ol! I I! I |_, | !,,.,, I |, ,I i I | |, | |, | |, | | I, !,, |t III oil * I I I III ! o,|, | Ill o,!

absent in the initial study, and coupling with the kinetics of film formation. This work is underway and a proposal

is in preparation.

We have determined the importance of substrate thermal control during the diacetylene derivative deposition, and

accomplished deposition of very, good films by physical vapor transport on a gallium arsenide substrate. Along

with observation of other systems, substrate thermal control has caused some interesting speculation on the

dynamics of film formation during physical vapor transport.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 1/91 EXPIRATION: 1/94

PROJECT IDENTIFICATION: 962-21-08-12

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Paley, M.S., Frazier, D.O., McManus, S.P.. Zutaut. S.E., and Sanghadasa. M. Diacetylene and polydiacetylene derivatives

of 2-methyl-4-nitroaniline for second-harmonic generation. Chemistry of Materials, vol. 5. no. 11. 1641-1644 (1993).

I I I I III II I II I II I I II I III I II I II III I II II I IIII III III III I I II III II I I I I I I II I I II I IIII III III III III III III III III III III III III Ill III IIIllllllllll III III I;11 III lllllll I II Ill III III III Ill III III III Ill IIII III Ill III lllll I II III I Itl itl !1111 |11111 II I I II II! I II $|1 | II I I

II-532
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

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Growth of Nonlinear Optical Crystals by Melt and Solution Processes

PRINCIPALINVESTIGATOR: Dr. Donald O. Frazier NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

B. Penn NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

Our objectives are to study formation of organic nonlinear optical (NLO) bulk composites and amorphous films

having excellent nonlinear properties under certain processing conditions. Detailed determinations of probable

gravity induced phenomena during processing will provide appropriate microgravity experiment rationale.

Another primary objective is to study dynamics of solution growth using organics, including certain peptides, with

,,ood nonlinear optical properties.

TASK DESCRIPTION:

The emphasis on organic crystals and thin films has shifted to composites and amorphous materials. This is due to

weaknesses in mechanical strength, optical defects, decomposition of pure CTyStalS grown by Bridgman-Stockbarger

techniques, and difficulty in achieving large areas of crystallinity in polymerized films. Some of the most

promising processing techniques in this area of research now include preparation of bulk composites of the active

NLO material in a polymer matrix, physical vapor transport, and the photopolymerization of diacetylene monomers

in solution.

A recent objective, therelore, is to assess methods of extending excellent third-order nonlinear optical organics in

solution to organics in polymer matrices. For optimal nonlinear properties and good optical quality, composition

is critical, and methods for achieving unili)rm and accura;e composition, quite specific. Solution methods include

photopolymerization of diacetylene derivatives, which yield amorphous thin films of excellent third-order

nonlinearity, as well as future crystal growth of peptides and other organics such as 4-N,N' -dimethylamino-4'

-N-methylstilbazolium tosylate (DAST) with very. high powder second harmonic generation (SHG) efficiencies.

The photopolymerization technique results in films of a polydiacetylene from a 2-methyl-4-nitroaniline diacetylene

derivative from monomer solutions onto UV transparent substrates. This process yields amorphous polydiacetylene

films with optical quality superior to that of films grown by start 'dard crystal growth techniques. These films have

excellent third-order NLO susceptabilities, and spatial selection of film deposits is stmple. Furthermore, there is a

compelling opportunity to study fundamental gravity related phenomena due to processing heat transfer dynamics.

Benzil in acetone results in novel third-order nonlinearities such a.s "'beam fanning" and transient multiple diffraction

rings. Transiency results from convective dissipation due to electrooptic and/or thermal effects. Dispersion of the

active NLO material throughout a polymer matrix, such as polymethylmethacrylate, is stabilizing and of

technological interest, however, it is important to optimize bulk concentration and homogeneity of the dispersed

phase. The gradient-freeze processing method may introduce gravity-dependent concentration inhomogeneities and

effect optical characteristics.

Future aspects of this program include synthesis of peptide derivatives (and DAST) with excellent second-order NLO

properties followed by a study directed at understanding processes occurring during the crystal growth of these

materials by solution methods. This project would also have value in understanding protein crystal growth

dynamics.
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

i i i o ill o I i | i Io o iu _ | i o o i _ o n J | i io in | n i o | i o i i o o II o | n o 111 n n s i i t ii o u i i n i o n i o ni n | I | | a o o I a g I I o uI o o n o o I a o I I I i I ao I Io | I o | I I | I I a I Io I ao | I o o I | o I a o III II _ I nl o II g I I a n na II o I n o I o o n| o 11o. o II o o ! | | I| | II o I I o I | | n I I IIII I o o I | o I I o I Io nI o | I o | I I I I o II o I I o n I o i I| I Io _ I o o I n ! i

TASK SIGNIFICANCE:

Many of the crystal/film growth processes appropriate for inorganic crystal growth and which amplify key elements

of microgravity materials processing are equally applicable to the growth of organic photonic materials. Indeed,

there is an opportunity to observe the effects of fundamental microgravity related phenomena not possible to study

in semiconductors. Furthermore, these materials may comprise a large share of the next generation of materials tot

computer applications.

PROGI:tESSDURINGFY1994:

In our work to study melt growth via the Bridgman-Stockbarger method of directional solidification, we have

determined that advantages can be derived from binary systems. Organics with nonlinear optical properties in a

solvent exhibits interesting third-order properties. This study was the focus of a Master's Degree and is currently

the subject of the incorporation of NLO materials in polymer matrices. These systems exhibit newly discovered

properties such as beam tanning and multiple diffraction rings, Dispersion of the NLO active component

throughout the polymer following a gradient freeze is the subject of potential microgravity processing.

We have discovered a novel technique for obtaining thin polydiacetylene films using photo-deposition from

monomer solutions onto UV transparent substrates. This method, to our knowledge, is unique and offers the

opportunity for fundamental microgravity studies and represents a significant advance in the technology of the

application of amorphous films having excellent nonlinear optical properties. The microgravity interest can be

derived, in part, from the heat transfer dynamics at the container solution interface which result from relative

absorption properties of irradiated UV light by the container and the solution. A patent application is in

preparation.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 1/91 EXPIRATION: 1/94

PROJECT IDENTIFICATION: 962-21-08-13

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

.Journals

Abdeldayem. H.A.. Sheng, W.. Vankateswarlu, P.. Witherow. W.K.. Frazier. D.O., Sekhar, P.C., Geroge, M.N.C.. Kospert.

L., and Wasielewski, M.R. Nonlinear optical parameters of 7'.7'-dicyano-7'-apo-B-carotene in hexane by self-action

techniques. Optics Comm., vol. 95. 295-300 (1993).

Aggarwal, M.D., Wang. W.S.. Choi. J., Chang, K.J.. Shields, A.W., Penn. B.G., and Frazier, D.O. A novel

Bridman-Stockbarger melt growth system for organic nonlinear optical materials. Meas. Sci. Technol., vol. 4, 793-795

(1993).

Henningsen, T., Singh, N.B., Hopkins, R.H., Mazelsky, R., Hopkins, F.K., Frazier, D.O., and Singh, O.P. Growth of

binary organic NLO crystals: m.NA-p.NA and m.NA-CNA systems. Materials Letters, vol. 20, 203-209 (1994).

_!_|_!_!_o_|_|_|s_l_!_!_|o_|_|_|_o!_|o|_ao|_ _|o__o_so__o|_oeo__!___|_o_|_||________Iu_I___!______o!____ao|__o____________!__!______||________|____a!_!__!e_!_o!______!__!______o____!__|_o||_____|oa________

11-534
Investigation qfi Local Effects on Microstructure Evolution

PRINCIPALINVESTIGATOR:Dr. Donald O. Frazier NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

J. Rogers

P. Downey

B. Facemire

B. Witherow

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The objective of this proposed work is to perform modeling and expertmental studies on the development of

microstructructures and the growth of a second phase in a two-phase system. Most modeling and experimental

studies locus on the average particle, and the late stages of growth processes. However, experimental observations

of dynamic local behaviors within the context of a particle ensemble are accessible by optical techniques, including

holography. Interest extends to examining these systems in 'all stages of growth within the limit of holographic

resolution. Additionally, holography provides and archives data to employ emerging techniques for measuring

diffusion fields during growth.

TASK DESCRIPTION:

The primary method of data collection is by the use of holography. The holographic techniques are crucial to

capturing the entire cell volume. A unique capability to apply phase shifting interferometry to holography is under

development by one of the coinvestigators of this work. With this technique it is possible to measure the

concentration gradients, hence diffusion fields, surrounding individual droplets. Such data, not attainable by any

other techniques, would provide essential input to computer models. Additionally, a two-color holography

technique, also under development by the same coinvestigator, may provide meaurement of spurious thermal

gradients over the lifetime of an experiment. It should be noted that use of narrow path-length ceils can introduce

the effects of "mixed"dimensionality, as observed in recent analysis of an experiment performed in this laboratory.

"Mixed" dimensionality refers to 3-D droplets located on a 2-D substrate. Such systems follow different scaling

laws than fully 3-D systems.

The research apoproach includes observation of diffusional growth of the secondary phase in a transparent

monotectic system. Ultimately, this work will rely on the benefits of microgravity processing to eliminate the

buoyancy caused by concentration or temperature gradients. Ground work requires a transparent isopycnic system.

Sensitivity to gravitational fields is tested, in the laboratory, by tethering two droplets in a test cell and comparing

growth kinetics at varying temperatures. Convective flows increase with increasing conjugate phase density

differences which are relatively strong functions of temperature. Quench experiments in narrow path-length cells

allow observation of local effects in an ensemble of droplets. Narrow path-length is a prerequisite for establishing

transparency quickly in high droplet density media.

TASK SIGNIFICANCE:

To a large extent, particle growth and distribution determine the mechanical properties of an alloy. An

understanding of microstructure is essential to predicting the behavior of a material with respect to, tor example,

metal fatigue. The unique capabilities provided by holographic techniques enabling observations of local effects

during diffusional growth of a second phase in a model, transparent two-phase system, allow detailed analyses of the

local dynamic and resulting microstructures. Additionally, holographic studies of droplet diffusion in model

systems are in agreement with Rutherford backscattering measurements of Ga and Sn "island" growth on Si.

Likewise, cloud dynamics derives some of its physics from such coarsening phenomena. Diffusional studies to

model the time evolution of the total surface area of particles comprising polar stratospheric clouds, for example,

suspected as catalysts for ozone decomposition, can be potentially important to the study of the rate of ozone layer

depletion.

_Q_I_I_I_e_t_e_i_I_I_*_e_I_I_*_I_i_i_e_I_*_1*_i__I_B_o_I_*_i_ij_I_en_I__l_mI_iI_B_

11-535
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

PROGRESSDURINGFY 1994:

This work has resulted in an experimental study of diffusional coarsening, or Ostwald ripening, in a liquid-liquid

two-phase system utilizing a 100 micrometer pathlength test cell. The discrete phase was nucleated on one wall of

the cell which resembles island formation in thin film growth. Observation of Ostwald ripening over a period of

lxl0 7 s (~ 4mo.) reveals that droplet number decay and the average radius increase, in the asymptotic limit, is in

good agreement with theoretical predictions for diffusional growth of spherical caps on a two-dimensional substrate

which is a valid approximation for the geometry of this experiment. This kind of geometric configuration is often

encountered in island evolution dynamics and phase segregation in thin films. Two approximate solutions were

developed, one to monopolar order, and the other to the dipolar order. Both approximations closely follow the

experimentally observed scaling laws characteristic for the mixed-dimensional coarsening. Certain deviations

appearing among the two approxtmate solutions and the experimental data, however, are suggestive of differences

between global and local effects.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-26-08-13

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Fradkov, V.E., Mani, S.S.. Glickman, M.E., Rogers, LR., Downey, J.P.. Witherow. W.K., Facemire, B.R., and Frazier,

D.O. Coarsening of three-dimentional droplets by two-dimentional diffusion: part II. theory. J. Electronic Materials,

vol. 23, no. t0, 1007-1013 (1994).

Rogers, J.R., Downey, J.P., Witherow, W.K., Facemire, B.R., Frazier, D.C., Fradkov. V.E., Mani, S.S., and Glicksman,

M.E. Coarsening of three-dimensional droplets by two-dimensional diffusion: part I, experiment. J. Electronic

Materials, vol. 23. no. 10, 999-1006 (1994).

I I I II I II i II I I I I I I I II I I I I I i I I I I i I II I I I I I I I I i I I I II I I I I I i i I I I I I I I II I I I I I i I I ii II I i i i I I I I I I I II I i i i i I i ii i ii i i I I I I i i i i ii I i I I I I I I IJ I I I I I li I i i I I I i I I I II t I i i i i I I I I I I I It I II I I i I I I I I I I I II I II I I I I I I I II I II I I i i I I I I II I I I I I I I I I I II I I I I I I I I I ii It I I i I I I I II I I I I I i i I I I I I

!1-536
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

Jo i o | i o | o o | i o o ii o b i i | J o o i i * i io i is |1 o ii J i a a | o oa ia o | I o ii o o t o i ia o Ii o | i o | _ o o o a o ia o |I i i i o o o i o i i o ia | o o o I | o i o | eo I I o o I I u i I o I I o | o o ! I o o i I o | i o | io ii o i i o o i a o i i o o o Io o o a i o o o i o o o i o i io o io i o o o i i J I i | o i i o | i oi i io i i e o I o o i i o o i a a n i a o i u in _ o o la o i o o no! a o o i o o _ o o | o oi o | i o i

Electronic Materials

PRINCIPALINVESTIC-_TOR:Dr. Thomas K. Glasgow NASA Lewis Research Center (LeRC)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

Particular attention is given to transparent materials of technical interest as modulators and detectors and of

scientific interest as demonstration materials for pattern tbrmation and fluid flow.

TASK DESCRIPTION:

The phenomena being studied include diffusion, coarsening, solution crystal growth, physical vapor transport,

pattern formation in solidification of aggregation, solute rejection and transport, and nucleation behavior. The

gravitational acceleration considered ranges from constant l-g to low- and variable g-levels (g-jitter).

TASK SIGNIFICANCE:

The important feature of this work is the coordinated approach; i.e., quantitative agreement is sought between

physical and numerical experiments. Attention must theretore be given to the development of diagnostic tools as

well as to advanced numerical techniques.

PROGRESSDURINGFY 1994:

Measurements of relative solid and liquid thermal conductivity have been made in support of ground-based research.

Work has continued on algorithms describing pattern formation and on mixing in variable acceleration

environments.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/92 EXPIRATION: N/A

BS Students: 1 PROJECT IDENTIFICATION: 962-21-05-02

MS Students: 1 RESPONSIBLECENTER: LeRC

PhD Students: 0

____________o__________!____!_!______________________________________________________a__!_____________________________________________n___________________________________________________________________________________ I I i I II I II I I I I I I I I II I I I I I I

11-537
Combustion Synthesis qfi Materials in Microgravity

PRINCIPALINVESTIGATOR:Prof. Irvin Glassman Princeton University

CO-INVESTIGATORS:

Dr. Kenneth Brezinsky

Prof. C.K. Law

Princeton University

Princeton University

TASK OBJECTIVE:

The experimental investigation involves detailed probing and quantification of the heterogeneous flame structure,

and the materials characterization of the nitride powders obtained. It builds on the experience already gained in a

related NSF-supported program examining the gas phases combustion synthesis of materials through metal/halide

exchange reactions. The theoretical investigation involves analyses of the propagation, structure and stability of the

heterogeneous flame, and the reaction mechanisms of individual metal particles in variable density.

TASK DESCRIPTION:

A comprehensive experimental and theoretical program has been initiated to synthesize metallic and nonmetallic

nitrides (especially titanium nitride) under microgravity conditions, and to understand the underlying combustion

mechanisms. The progress applies the Self-propagating, High-temperature Synthesis (SHS) technique to titanium

(or other metal) particle suspensions in supercritical nitrogen: the nitride particles are formed upon passage of a

serf-sustained flame through this suspension.

TASK SIGNIFICANCE:

Microgravity prevents particle settling, agglomeration, and liquid/metal film formations and permits the use of

suspensions of particles of specified characteristics. This facilitates the production of nitride powders of high

purity, uniformity, and specificity. The novel use of supercritical nitrogen to provide a supply of reactant at

conditions near the critical temperature and pressure avoids bubble formation that occurs when liquid nitrogen is

used and also providesa means for greatly changing reactant density with a modest change in pressure because of the

very high isothermal compressibility near the critical point.

PROGRESSDURING FY 1994:

Titanium powders immersed in near super_xitical nitrogen in a temperature range of 126.26-141,75 °K and a pressure

range of 3.4-6.8 MPa, have been converted to titanium nitride by sell-propagating high-temperature synthesis

(SHS). Both packed pellets and loose powders have been nitnded by this method. The conversion yields to

titanium nitride for the loose powders are higher than those reported in the literature for pure titanium powders

combusted in nitrogen at any other conditions. However, the conversion yields for the packed titanium powders

were significantly lower than those for the loose powders and lower than obtainable when liquid nitrogen instead of

supercritical nitrogen was used. In addition to the titanium powders, loose tantalum powders have been nitrided in

supercritical nitrogen but the yields obtained are lower than those reported in the literature for room temperature

ignition at comparable pressures. Loose silicon powders could not be ignited in this media.

In order to conduct the experiments described above, a cryogenic, constant volume reactor was designed and

constructed. The reactor not only met the materials requirements to safely contain a high pressure, low temperature,

supercritical nitrogen medium, but also generated the nitrogen working conditions from standard nitrogen sources.

The reactor was equipped with optical access ports so that the progress of the combustion synthesis could be filmed.

Progress in the theoretical understanding of nonadiabatic heterogeneous flame propagation and extinction was

achieved through an analysis based on a premixed mode of propagation for the bulk flame supported by the

non-premixed reaction of dispersed non-metals in the liquid metal. The fonnulation "allows for volumetric heat loss

I1-538
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

throughout the bulk Ilmne. finite rate Arrhenius reaction at the particle surlace, and temperature sensitive Arrhenius

mass diffusion in the liquid.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 1

TASK INITIATION: 11/92 EXPIRATION: 10/95

PROJECT IDENTIFICATION: 962-26-05-09

NASA CONTRACT NO.:NAG3-1418

RESPONSIBLECENTER: LeRC

I _________________________________________________________________________________________________________________________ OI __________________________________________________________________________________________________________ OllllloulOIIol

I1-539
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

o ! oo o I ! o i o|l o i a| | | ii noi ! I | | o I o o a I II o DI o I ii | o ! II! o | i | |i | i | i o | | | i| i i | ia | io | I o I o a I I I OI I 0 | oOo o I | I I o l o o oo | o o o o I o I I I H i Ii el I o H I H O IOOo I I I HI | o a i _4 o a o o | o i * l a I | ! i a 11 o i II II o t i o a I I o o o | i aI n io i i | o o | | o i a ii a I o o I I I i i i i ao ia o iII I o I I Io i | ! I a I o a a i i o Ii o. | a o a | o o | I

Evolution of Microstructural Distance Distributions in Normal Gravity and Microgravity

PRINCIPAL INVESTIGATOR: Prof. Arun M. Ookhale Georgia Institute of Technology

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

1. To develop the methodology for estimation of distributions of distances between microstructural features in

microstructures by using digital image analysis and stereological techniques.

2. To apply the methodology to study the evolution of microstructural distance distributions during some

important materials processes such as: particle coarsening, liquid phase sintering, etc.

3. To quantify the relative contributions of intrinsic process dynamics and gravity on the evolution of

microstructural spatial distance distributions.

TASK DESCRIPTION:

Digital image analysis techniques will be applied to obtain the centroid coordinates and the size of each

microstructural feature of interest observed in a two-dimensional section through three-dimensional microstructure.

The 2D microstructural distance distributions will be extracted from these data via a suitable computer code.

Stereological methods will be utilized to estimate the true 3D spatial distance distributions from the apparent 2D

distance distributions. The methodology will be applied to study the evolution of distance distributions during

particle coarsening and liquid phase sintering in normal gravity, and subsequently in microgravity.

TASK SIGNIFICANCE:

An important benefit of processing of materials in microgravity would be the control of distribution of spatial

distances between microstmctural features, and the consequent gain in the material properties. This research

program will develop the techniques for quantitative cbaracte, rization of spatial distance distributions to objectively

gauge the relative contributions from intrinsic materials process dynamics and gravity to the evolution

microstructural distance distributions. The resulting information should be very useful to understand and model the

role of gravity on microstructural evolution during materials processes.

PROGRESSDURING FY1994:

This research project started on July 11, 1994. During the ftrst three months, the efforts were devoted to complete

the development of the interactive software to extract the centroid coordinates of microstructural features in a series

of microstructural fields (say 50 contiguous fields) referred to the same origin, so that the distances between the

features, not necessarily in the same field of view, can be computed. The technique will be applied to obtain some

preliminary data on some specimens of liquid phase sintered material provided by Professor R.M. German of

Pennsylvania State University.

STUDENTSFUNDED UNDER RESEARCH: TASKINITIATION: 7/94 EXPIRATION: 7/96

PROJECTIDENTIFICATION:962-25-05-29

NASA CONTRACTNO.:NAG3-1651

RESPONSIBLECENTER: LeRC

o0aleooonueeeoee elleeleeeee|eeo!oeanoee lie eeoeeelDoeeeooeelleeOO(Jenl eli I i| e|a eeee!e!lelaelo lee n l elie lenin e|l DldUlea eeleule!!el!oaueeemln eea eeoc eoqueoleee! eel eel eel eeaeoaeea ee! eeeloeo lie !le leo !ooanoo!oe Iteoa eoleole olenl| la ea ! i|a |||nlnunle! eel |lo |e! eo | eo

I1-540
Influence of Free Convection in Dissolution

PRINCIPALINVESTIGATOR: Prof. Prabhat K. Gupta Ohio State University

CO-INVESTIGATORS:

S.A. Korpela

A.R. Cooper

Ohio State University

Case Western Reserve University

TASK OBJECTIVE:

To study the influence of natural convection in dissolution of silica glass into a melt consisting of PbO and SiO_.

TASK DESCRIPTION:

The tollowing two-part task has been undertaken. The first portion of the task consists of designing an

experimental apparatus. The second portion of the task involves the design of a computer program for theoretic_d

calculations. Each portion of the task is under way.

TASK SIGNIFICANCE:

The _n of the research is to understand the influence of tree convection in dissolution dynamics of solids subjected

to a corrosive environment. In terrestrial applications a better understanding of this phenomenon should lead to

savings by way of improved life of silica liners in contmners used in batch processing of various corrosive

materials. The aim of this task is to achieve a good enough theoretical model so that the proposed ground based

experiments can be faithfully simulated via computer calculations.

PROGRESSDURING FY1994:

The composition of 50 mole percent PbO - 50% SiO 2 has been selected as the melt and pure silica as the solute to

examine the influence of tree convection on dissolution. The density variation with mole percent of silica is found

to be linear with a slope of 0.081 g/cc per mole percent of PbO. A student in Mechanical Engineering has initiated

setting up the fundamental equations describing the dissolution phenomenon in presence of free convection.

STUDENTSFUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 1

TASK INITIATION: 6/94 EXPIRATION: 5/95

PROJECT IDENTIFICATION: 962-25-05-24

NASA CONTRACTNO.:NAG3-1602

RESPONSIBLECENTER: LeRC

_o_$_II_I_g_I_i_t_D_I_I_I_o_I_D_I_a_tI_B_o_o_*_*D_I_#_B_t_o_*_*_l_B_B_*_*_B_I_j_#_B_I_

I1-541
Noncontact Thermal, Physical Property Measurement of Multiphase Systems

PRINCIPALINVESTIGATOR: Dr. Robert H. Hauge Rice University

CO-INVESTIGATORS:

J.L. Margrave Rice University

TASK OBJECTIVE:

The long range goal this equipment development effort is to create a prototype measurement facility for the physical

and chemical properties of levitated samples. Our objectives are as follows:

1. To determine the capabilities and accuracy of newly developed techniques for measurements of surface optical

properties, density, temperature and surface tension of levitated solids and liquids,

2. To test the overall performance of current concentrators in combination with controlled gas flows and axial DC

magnetic fields with respect to the creation of axially symmetric RF fields and control of liquid sample rotation,

vibration and translation.

TASK DESCRIPTION:

Measurement techniques for the properties are as follows:

1. Temperature: A simultaneous measurement of sample brightness at a vareity of wavelengths through the

visible and near infrared is obtained along with the sample emissivity and optical constants at 632 nm.

2. Density: A triggered high-resolution video camera image of the liquid drop is obtained with backlighting of the

sample by a 670-rim diode laser. Images are taken when the sample has spherical symmetry, and the density is

obtained from a calculation of volume with use of an accurately determined sample profile.

3. Surface tension: Surface-tension measurements are obtained from the vibrational frequencies of the oscillating

drop. The vibrational frequencies are obtained from a frequency analysis of reflected or emitted light.

4. Electromagnetic levitation coils: Current concentrators which provide both vertical and lateral electromagnetic

symmetry have been developed for efficient EM coupling to the sample and improved symmetry of the positioning

forces. Symmetries other than cylindrical are under investigation as a means of controlling sample rotation.

TASK SIGNIFICANCE:

Accurate methods for measuring liquid metal physical properties will permit improved modeling of liquid metal

flows in direct coating of metals to near final dimensions.

PROGRESSDURINGFY 1994:

Measurements of the temperature dependence of the optical constants and emissivity of gold has demonstrated the

accuracy of the PEM ellipsometry method for levitated samples.

Surface tension measurements of gold indicate the current methods of modelling the effects of external levitation

forces do not work well for samples with large amplitude motions.

Coupling of large DC currents to the levitation coil was found to be not effective in suppressing sample rotation.

i i Ii Ill III I I I I I II i I I I III II i HI I I I I I I II I I I I I I I I i I I I II II I I I i I I I II I I I I I i I i Ill I I I I I I I I I I I i i I I I I I I I I I I I I II I I I II III I I I I I II I I Ill I I I 1111 il I I I I I II I I I I I |i i II I I I I I I I I I I l II l I I I I I Ill I II I I I Ill I I I I I I II III I I I I I I I I I II I I I I I I I i III I iI I II I I I I I i Ii i i i i I i I I i i i ii i i i t I i

I1-542
STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 0 MS Degrees: 0

PhD Students: 1 PhD Degrees: 1

TASK INITIATION: 12/91 EXPIRATION: 11/94

PROJECT IDENTIFICATION: 963-25-07-04

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Hauge, RH., P. Lee. T. Baykara, and J. L. Margrave. "A review of containerless thermophysical property measurements of

liquid mnetals and alloys", High Temperature Science. (To be published).

Proceedings

Xiao, Z.L., K. E. Pryor, L. Y, Liu, J. L. Margrave and R. H. Hauge. "Containerless thermophysical property measurement

for liquid metals." Proceedings of the 6th Intern. Syrup. on Experimental Methods for Microgravity Materials Science.

123rd TMS meeting Feb, 1994.

!!Olll!lOSnlm0111lllll!llll|l!!llnlU!lllll|!!lll!ull$!l I!llllllllelle!!l!!lllllllOllll!!ll!!l I!111 I1! I1|1 lelll||ll!l!lll IIIIlellll!lll Illl Oiill IIII 10111|l II!lllll Ill IIII IIIIOl III I ISI Ill I!11 Oil !l|lllllllll I$||lOllll I!1111 ! I I I II II ! I I I ! I I I I I I II ! | I o

!1-543
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

Microgravity l'roces_in,k, q/ Oxide Superconductors

PRINCIPALINVESTIGATOR: Dr. William Hofmeister Vanderhilt University

CO-INVESTIGATORS:

R. Bayuzick

R. t-]opkins

M. Vlasse

V_mderbih Uniw:rsity

Westinghouse S&TC

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

Since the discovery of superconductivity in lanthanide-based perovskite systems, considerable eflbrt has concentrated

on the synthesis and characterization of these materials. Melt processing techniques have shown great promise m

developing bulk crysudline materials with critical current densities necessary for practical application. The

YBaCuO system has received the most intense study, as this material has shown promise tbr the application of

both thin film and bulk materials. However, little information is available on the complete melting relations,

undercooling, and solidification behavior of these materials. In general, the understanding of undercoolmg and

solidification of high temperature oxide systems lags behind the science of these phenomena m metallic systems.

Therelore, this research will investigate the fundamental melting relations, undercoolmg, _md soliditicatmn behavior

of oxide superconductors through melt processing, with an emphasis on improving ground based synthesis of these

materials. The techniques developed by this project will apply to oxide superconductors m general and will provide

additional aveTmes lor research in this field. An additon'al goal of this program is to develop collatx)ralion with other

groups and provide access to the unique processing strategies developed by the microgravity progr_un.

TASK DESCRIPTION:

The proposed research will continue experiments with YBa2Cu_OT_d using drop tubes at Vanderbilt University, the

105 meter drop tube at Marshall Space Flight Center, and aero-acoustic levitation at Containerless Research. Inc.

Microstructural and compositional analyses will be performed at both Vanderbiit University mid die Westinghouse

Science and Teclmology Center. Application of acoustic levitation and microwave heating at the Jet Propulsion

Laboratory, electrostatic levitati(m at file Jet Propulsion Laboratory, undercooling combined with rapid heat removal

in the Undercool and Rapid Quench Technology (URQT) drop tube at Vanderbiit, and addition of small anmunts of

Ag to the material for improving electromagnetic susceptibility will be explored and incorporated if the techniques

prove useful. In order to correctly assess thermal profiles ulxm melting and solidification in aero-acoustic

levitation experiments, the Ultra High Speed Thermal hnager (UHSTI) a! Vanderbilt University will be milized.

TASK _IGNIFICANCE:

Since the discovery of high-T_, superconductivity in copper oxide systems, much progress h_ts been made in the area

of thin film technology fi)r sm_dl scale applications. However, the science suffers from the lack of crystalline

materials with high critical current densities that are large enough for bulk or large scale applications. Melt

processing in general has proven to be the best technique tbr producing bulk materials with significant critical

current densities (<104 tunp cm _"m melt texturing experiments).

The novel techniques developed in this study have brought new insight into the understanding of the phase relations

in this complex system. These enhancements will help to advance the understanding of the science (if high-T_

superconductivity and of the material properties of oxide superconductors. Advancements have a direct Unpact on the

production of bulk materials for large scale applications.

nol q¢n, 1, ,tu a.n on; i_l, u., If, otn Ill,In a,,,,, I ,o, I_l ,llO,aa In Ill, lilt, aonaon u,,,|l tOll |,,||O|||,,,a|OO|O|IIOI UIIUOIIonI|IIugI|,IOISOl Ion aO,OaHIOO nI ,IOlll Uon U01 OO| nlonaonlooaonlsnsollolsol,mHmuoosoollol,oulaa,ol|oola ,U aol aol I.n Ion aonlon,.ha.nll

II-544
PROGRESSDURINGFY 1994:

In addition to the drop tube experiments performed over the past three years, investigations have been initiated into

aero-acoustic levitation (AAL) using the facility at Containerless Research, Inc. in Chicago, IL. This techinique

allows for processing samples ranging in size from 2 - 3 mm. In these experiments, samples were completely

molten, and upon solidification, a pronounced recalescence event occurred. Two different microstructures resulted.

One consisted of primary tetragonal YBa2Cu3OT.d dendrites and a mixture of several phases including fine dendrites

of Y4Ba3Og. The second microstructure which developed consisted of single phase tetragonal YBa,Cu3OT._. The

formation of a single phase indicates that samples were undercooled to well below 1273 K. Upon annealing in

flowing oxygen, these samples revert to the superconducting orthorhombic structure and exhibit critical current

densities on the order of 103 A cm 2 up to about 45 kOe applied magnetic field at 5 K.

Experiments have also begun to determine the electromagnetic susceptibility of YBa_Cu3OT.d. using RF frequencies

in the megahertz range. These experiments will ultimately include small additions of Ag into the structure in an

attempt to enhance electromagnetic susceptibility. Also, preliminary, experiments have begun using the UHSTI

during aero-acoustic levitation experiments.

STUDENTSFUNDED UNDER RESEARCH: TASKINITIATION: 11/94 EXPIRATION:11/96

PROJECTIDENTIFICATION:962-25-08-22

NASA CONTRACTNO.: NAG8-832

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Olive, J.R., Hofmeister, W.H., Bayuzick, RJ., Carro, G., McHugh, J.P., Hopkins, R.H., Vlasse, M., Weber, J.K.R.,

Nordine, P.C., and McElfresh, M. Formation of tetragonal YBa_CthO_. d from an undercooled melt. J. Mater. Res., vol. 9,

no. 1, 1 (1994).

Presentations

Hofmeister, WH., Olive, J.R., Bayuzick, R.J., Carro, G., McHugh, J.P., Hopkins, R.H.. Vlasse, M., Weber, J.K.R.,

Nordine, P.C., and McElfresh, M. "Formation of tetragonal YBa_Cu_OT_ from an undercooled melt." Poster presented at

the MRS Annual Meeting, Fall 1993, Superconductivity: Materials and Processes Symposium. Boston, MA. November,

1993.

i l ill Illlel Ill Ill tl Illlllll lie Ilnlell el I Ill ell Ill eli ell I II IlI I III Ill I I I lI I l I I III l II l Ill lel I el III I Ia III Ill IIllllllllllllll IlUll III Ill Ill Ill nl nenlllll Ill ll l llllllllllel I till lea tO I llll III Ill ellnlntl I I III I Ill III l I I el I l Il el I l IIl I Il IIl I I li iII I

11-545
lI. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

,lI,l,,,Im,_,l|i*,J,l|H.Hll''''*'l*|Hll*'l"l|_l'*''*''t'l'*J''''''''' .l"ll*''l''Hll''*'l*0tltl''lllf tH H,IHl',lJ'¢H'll'lIHa'tl|¢lIHIHl*ll'|l'H*H"l|''lH**'|J'llHl"l*!l|' H I0111'*|HIH'tlllm mlHml,. ,H |Hl,,l,ll,ll¢

Non-Equilibrium Phase Transformations

PRINCIPALINVESTIGATOR: Dr. Kenneth A. Jackson University of Arizona

CO-INVESTIGATORS:

B. Zelinski University of Arizona

TASK OBJECTIVE:

Our computer stmulations have resulted in a breakthrough in our fundamental understanding of the physics

associated with phase changes which take place far from equilibrium. This includes solidification, especially rapid

solidification, crystal growth, especia.lly orientation effects on segregation, condensation from vapor, etc. The goal

of this program is to continue computer simulations and to initiate an experimental study to explore the

implications and insights provided by this breakthrough.

TASK DESCRIPTION:

The expertments involve an an',dysis of microsegregation that requtres a microgravity environment to minimize the

effects of convection. A program combining simulations with experimental studies is viewed as essential, not

only in providing new insights for the experimental work, but also in keeping the simulations relevant to the real

world. Experimental studies of the microsegregation of dye molecules during the crystallization of transparent

organic compounds will be pursued. These experiments will require verification in a convection-free environment.

The computer simulations to date have clearly demonstrated the difference between the diffusionless and the

diffusion-dominated regimes of growth. There is still much to be done in this area, and the studies to date are but a

beginning: they demonstrate that this method of simulation can indeed capture the essence of transformauons that

occur in the real world. This simulation method will be used to explore, in detail, the transition between the

diffusionless regime and the diffusion-dominated regime. It will be used to predict growth rates, transformation

temperatures, and translbnnation-induced segregation effects. It will be used to study the early stages of interface

instability, including not only the growth rate dependence of the distribution coefficient, but "also the effects of

having a crystal composed of discrete atoms growing into an alloy that has randomly-distributed atoms rather than a

crystal bounded by a mathematical surface growing into an alloy of uniform composition.

TASK SIGNIFICANCE:

The structure and properties of materials produced by transformations that occur under conditions that are tar from

equilibrimn is one of the central topics of materials science. It has been observed experimentally in many

materials that the distribution coefficient depends on the growth velocity and on the orientation of the crystal surface

during growth. These are not equilibrium phenomena which can be described by the standard quasi-equilibrium

thermodynamic mo.lel. Monte Carlo computer simulations have reproduced these phenomena and predict that they

depend on the undercooling, on the growth rate, and on the diffusion coefficient in the fluid phase. These effects are

particularly important in the rapid growth regime or more generally, in a regime where the phase transformation

takes place tar from equilibrium. Projects supported by NASA using levitation and the 0-g environment are

making major contributions to our understanding of nucleation and crystallization under these conditions, in the

regime where these non-equilibrium effects are very important. Our simulation results provide a new framework

for the interpretation of these experiments.

PROGRESSDURINGFY1994:

An an',dytical model has been developed which describes most of the features of the simulations. The model predicts

a growth rate curve which has a loop in it at high concentrations, so that there are regions where the growth rate is

not a single-valued/'unction of temperature. This loop accounts for oscillations in the growth rate which have been

observed during laser melting of alloys, and for the jump in growth rate as a function of undercooling which has

been observed in measured growth rates of alloy dendrites. The model includes the composition dependence of the

II-546
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

i.luo H o..oll.aoolooolo..i.ua0o .oon.aool.o*.a .i.laooollso|a.l.a.o.aoH .a. "m"i"_i_H_m_m_I_I_lu_II_I_È_l_l_*_I"I"l_*IÈ_1_l_*I|_u_Il"" H0 Jol.u .Hal. o lao.1o*lola.au H olaonaol

k-value discussed below. We have explored a range of compositions in the Monte Carlo modeling. The segregation

coefficient in the simulations does not depend on composition lOTdilute alloys, but is strongly composition

dependent for alloys with greater than about 5% of alloy concentration. These observations have led to the

development of an analytical model based on a novel functional form for the k-value as a function of growth rate.

Simulations in three dimensions show results which are similar to the simulations in two dimensions, but these are

quite different from simulations in one dimension. We understand why this is so: the connectivity of the interlace

enables energy to be transferred between atoms at the interface, This can occur in two- and three-dimension, but

not in one-dimension. Code is being developed to incorporate a temperature gradient into the Monte Carlo program

for simulations of cellular growth. This code will also be capable of modelling the phenomena of fluctuating

growth rates which have been observed during the laser melting of alloys. This phenomenon involves an

interaction between the non-equilibrium growth rate and the temperature gradient. We have so far been unable to

identify a system suitable for the study of the incorporation of dyes into organic crystals, although dozens of

systems have been evaluated. We plan to invert this process to study the crystallization of organic dyes containing

impurities. A Bridgman apparatus is being constructed which will be used to measure the growth rate and

orientation dependance of the incorporation of dopants into InSb. A solution growth apparatus is planned which

will be used to measure the growth rate and orientation dependence of impurity incorporation into water soluble

crystals during growth. These ground-based experiments are subject to uncertainties due to convection, and the

experimental results will require verification in a convection free, 0-g environment.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: O

MS Students: 0

PhD Students: 2

TASKINITIATION: 2/93 EXPIRATION: 2/96

PROJECTIDENTIFICATION:962-25-08-29

NASA CONTRACTNo.: NAG8-944

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Jackson, K.A. Theory of crystal growth from the melt. Ceramic Trans.. vol. 30, 95 (1993).

Jackson. K.A.. Gilmer, G.H., Temkin, D.E., Weinberg, JD., and Beatty, K. Non-equilibrium phase transformations. J.

Cryst. Growth, vol. 128, 127 (1993).

Proceedings

Jackson, K.A. "Nucleation." Crystal Growth and Epitaxy, Proceedings of the Valais Physical Society, HJ. Scheel, ed., 65

(1993).

Jackson, K.A. "Crystal growth kinetics." Crystal Growth and Epitaxy, Proceedings of the Valais Physical Society, H.J.

Scheel, ed., 81 (1993).

Jackson, K.A. "Introduction to the modern theory of crystal growth." Proceedings of the 8th International Summer

School on Crystal Growth.

Jackson, K.A., Gilmer, G.H., Ternkin, D.E., and Beatty, K. "Microsegregation." Proceedings of the East-West Surface

Science Workshop '94 (1994).

Presentations

Jackson, K.A. "Microsegregation." Invited Presentation at the East-West Surface Science Workshop '94 , February,

1994.

Jackson. K.A. "Non-equilibrium phase transformations." NASA Microgravity Materials Science Conference, Huntsville.

AL, May 24-25, 1994.

Jackson, K.A. "Microsegregaton and non-equilibrium crystallization." Invited Presentation at the AACG-West

Conference on Crystal Growth, June, 1994.

Jackson, K.A. "Optical materials in microelectronics." Invited Presentation at the Glass Conference in honor of Prof.

Norbert Kriedl, July, 1994.

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II-547
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

i ii; i i i i | i i | i i !i | g i i | | i i i _ i i i 1o | ii | ¢ i a i lilt a I I I | III | I I II I I | I I I I I SI I I | III _ I t t 14 | I I I | I I II I ! J I ! t | I | | tt III ¢ |1 S| I t H * | I011111011 | I II I I I t I I 0 ! I I I _ | t I I_ II I | I | 0111 t f I I m!t I! I I I I | I 0 | | | | I I0 | II I I Ill | | t | I II | I t I I t t I I I I It I I t t I t I I t I III I I I I I | I I _ I t| I _ |! I | | I _ _ I I I |

Combined Heat Transfer Analysis of Crystal Growth

PRINCIPALINVESTIGATOR: Dr. Mohammad Kassemi NASA Lewis Research Center (LeRC)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The technical objective of this research effort is to provide a quantitative understanding of the role of radiation heat

transfer on crystal growth in low-gravity space experiments. To accomplish this goal a generalized combined

conductive-convective-radiative numerical model is developed which can accommodate various crystal growth

experiments.

TASK DESCRIPTION:

Radiation heat transfer affects crystal growth in both space and ground-based processing. This is due to the high

operating temperatures of the crystal growth processes, the semi-transparency of the crucible and phase change

materials and the heat transfer link between the crucible and the furnace. In ground-based experiments, radiation and

convection coexist and compete lot dominating the heat transfer process in the ampoule. The role of radiation,

however, becomes more prominent in low-gravity environment of space where convection heat transfer is

considerably minimized.

A numerical methodology was developed for radiation exchange in the generalized multi-dimensional cylindrical

geometries encountered in crystal growth. The radiation scheme which is based on the Discretized Exchange Factor

method (DEF) uses node-to-node exchange to calculate radiation heat transfer in an absorbing emitting scattering

non gray medium. One of the advantages of this radiation model is that it can be easily incorporated into existing

t_ite difference or finite element codes.

The radiation model was incorporated into a finite element code for fluid flow and heat transfer and a generalized

radiation.convection-conduction model was developed for crystal growth in cylindrical ampoules. The solution

algorithm tracks the movement of the interface during the solidification process and adjusts the finite element mesh

to accommodate changes in the shape and position of the growing solid. Radiation view factors are also

continuously update as the geometry is altered.

TASK SIGNIFICANCE:

Low gravity simulations performed using the combined heat transfer model, clearly indicate that radiation effects are

dominant during solidification of oxide crystals, such as BSO, and may cause highly stretched and curved interfaces

during low gravity solidification experiments. The convection-conduction models that do not include radiation

effects rigorously cannot be used to predict the shape and movement of the solidification front correctly.

Thermal radiation governs the energy balance in many earth and space processes. It plays a crucial role in production

of glasses, semi-conductors, and advanced pay-off materials such as optical crystals. This study is geared towards

understanding the effects of radiation heat transfer on crystal growth in both low-g and 1-g environments and to seek

possibilities of exploiting these effects for improving the quality of the growing crystal.

PROGRESSDURING FY 1994:

A generalized radiation-convection-conduction model was developed for crystal growth in Bridgman furnaces. The

validity and accuracy of the radiation scheme was tested by comparing results to benchmark limiting solutions

available in the literature. Combined heat transfer and fluid flow models were developed for solidification of two

oxide crystals BSO (bismuth silicate) and YAG (yttrium aluminum oxide garnet). Both crystals are transparent to

II-548
radiationbelow6micronsandopaquetoradiationintherestofthespectrum. The models are based on actual

experimental configurations and conditions and include the effects of the furnace and the crucible wall. Results of

numerictd simulations which are also corroborated by qualitative experimental evidence clearly indicate the

solidification of both BSO and YAG is greatly influenced by thermal radiation. The shape and position of the

interlace can be grossly misrepresented if radiation effects are neglected.

In low-gravity experiments, radiation loss through the semitransparent solid dominates the heat transfer at the

solidification front for both materials and results in a highly stretched parabolic interface shape which protrudes

convexly into the melt. As a result, the fluid flow pattern is also substantrally modified.

In l-g solidification of BSO, convection in the melt also plays an important role. In this case, heat transported by

the recirculating vortices near the interlace produces and interlace which is much flatter than the correslxmding low-g

case.

Numerical experiments also indicate that because of the dominant role of radiation during solidification of

semi-transparent crystals such as BSO and YAG, a flat interface shape can only be achieved by minimizing the net

radiative loss from the interlace through the solid. This is valid for both l-g and low-g applications.

The study will be extended to include other oxide and semiconductor crystals with transparent bands. Efl'_ks of

different crucible materials and furnace profiles will be investigated. A Monte Carlo radiation model will be

developed to investigate the intricate effect of varialaon in the index of refraction across the interlace.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-21-05-10

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHICCITATIONS FOR FY 1994:

Journals

Kassemi. M., amd Naraghi, M.NH. Combined heat transfer and fluid flow analysis of semi-transparent crystals in low-g

and l-g solidification. J. Crystal Growth, (submitted).

Kassemi. M. and Naraghi, M.NH. Analysis of radiation-natural convection interactions in l-g and low-g environments

using discrete exchange factor method. International Journal of Heat and Mass Transfer. vol. 36. no. 17, 4141-4149

(1993).

II-549
Il. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

nz_IH_|_n_i_nn_In_In_|_"_n|n_in_"n|_"_I_"n"_i_I1l_i_I_n_n_i_n_ i iil.llelll|lllu i iiiii.ii|nnHl|ol.ll.llllu H III i il.loH IH I IIIII.II"IUI|IllUI"I'IHII0111111mlIII|H H .llllnllllnl||lOll||llH loll|

Fundamentals of Thermomigration off Liquid Zones Through Solids

PRINCIPALINVESTIGATOR:Prof. Michael J. Kaufman University of Florida

CO-INVESTIGATORS:

R. Abbaschian

A. Gokhale

University of Florida

University of Florida

TASK OBJECTIVE:

Currently, significant resources in terms of expert manpower as well as direct costs are being expended to develop

advanced materials such as the high-temperature structural intermetallics MoSi: and NiAI, and the fast

semiconductors GaAs and GaSh. Despite considerable efforts in these areas, the intrinsic properties of many of

these compounds, and alloys based on them, remain poorly understood to the degree needed to erdaance their

development and application. For example, it is unclear if the brittle nature of many of the intermetaUics of current

interest is an intrinsic property of these compounds or is associated with interstitial impurities or impurity phases.

Consequently, there is a need not only to produce single crystals of controlled purity, perfection and orientation, but

'also to understand the details of interlacial atomistics during crystal growth in order to bring about such control.

For many of the exotic compounds of technological interest currently, conventional crystal growth techniques have

not proven successful in this regard because of the many problems associated with container contamination or loss

of stoichiometry due to preferential vaporization of one or more of the elements with high vapor pressures (e.g.

arsenic in GaAs, antimony in GaSb, silicon in MoSi2, and aluminum in NiAI). In addition, these conventional

techniques are not amenable to a scientific study of correlations between thermosolutal convection and key aspects

of crystal growth such as the interlace (growth) temperature and morphological stability. For example, the use of

electromagnetic induction to produce float zones introduces an additional electromagnetic stirring component in the

liquid zone and also precludes the use of most sensors to measure interface temperatures.

TASK DESCRIPTION:

Although this method was discovered more than 35 years ago, there have been few attempts to utilize it as a means

for processing materials in spite of the fact that most materials typically can be processed (e.g., grown as single

crystals, joined and sectioned) at temperatures well below their melting points. In addition, coupling of this scheme

with both acoustic emission/reflection and possibly Seebeck techniques should allow the interlace positions, zone

length, and interface temperature to be monitored in situ in real time.

TASK SIGNIFICANCE:

The focus of this research is intended to circumvent the common problems (e.g. crucible contamination and loss of

stoichiometry) associated with conventional crystal growth methods by using the relatively unique technique of

TGZM to grow single crystals of materials of current technological interest. In addition, the low-growth

temperatures require much lower power inputs and result in enlaanced safety during both ground operations and space

flight. Also, it is anticipated that significant, hitherto unavailable data on liquid diffusivities will be generated

during these experiments. Finally, it should be emphasized that the capability of producing high quality,

inexpensive crystals of some of these rather exotic compounds could greatly facilitate advancements in these fields

of current technological interest.

PROGRESSDURING FY 1994:

Research efforts in FY94 have tbcused on the design, assembly and implementation of experimental equipment to

conduct the rather unique TGZM processing. Based on the considerable oxidation problems encountered in our

initial studies in a relatively crude furnace with limited capabilities in terms of atmosphere control, a new TGZM

furnace with high vacuum/purified inert gas capabilities was constructed and is currently being used tbr our attempts

__aI_jo_____D_D_t_e_I_D___D_e_

11-550
atprocessingGaSbusingaGazone.Thisvacuumchamber providesasufficientlycleanenvironment whichha_s

proventobeacriticalfactorinthedevelopment ofhisprocessinboththecurrentGaSb/GaandpreviousSi/AI

systems. The current chill/furnace assembly produces temperature gradients across the zone comparable to those

reported in early TGZM studies. Our preliminary, attempts with the GaSb/Ga system have been encouraging and it

appears that we are now in the position to concentrate on further development of the TGZM processing parameters,

characterization of the critical lactors related to the movement of the zone, and an',dysis of the various mechanisms

involved in the TGZM process.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 2

TASK INITIATION: 2/93 EXPIRATION: 2/96

PROJECT IDENTIFICATION: 962-21-08-16

NASA CONTRACT NO.: NAGS-946

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Adams, T.M., Paxton. D.M.. Gokhale, A., Abbaschian. R., and Kaufman. M.J. "Thermomogration of liquid zones through

solids." Proceedings of the NASA Microgravity Materials Science Conference. 41-42 11994).

11-551
It. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

ilil|n_in_i|ni|j|nain_i|M||_||n||M||i|I_ii_|ii|inni|mii_nin_eI_ni_!_in_i_i|_ Jl|lnnlnl||ll|ll|lll|lni||ll|ll||alnlll|llll|!lllonllllllnll Jll|ll0|tlll|lnlllllln!t illlnDill!llnl Jlllel!llnllllllIllIl|linJnllllll!ll|llm|l||ag JJIHiJllol!illl|lll

Kinetics of Phase Transformations in Glass Forming

PRINCIPALINVESTIGATOR: Prof. Kenneth F. Kelton Washington University, St. Louis

CO- INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objectives of this research are to develop computer models tor realistic simulations of th'st-order phase

transtormations, in particular crystallization of liquids and glasses, and to design experiments to test those models.

This research will lead to improved methods for the analysis of kinetic studies of these transtbrmations, allowing,

Ibr example, kinetic parameters tbr nucleation and growth to be determined from peak profile studies of

nonisothermal differential scanning calorimetry (DSC) measurements of crystallization. These new techniques will

have wide applicability lor phase transtbrmation studies. In particular, they will allow real-time experiments of

phase stability and transformation to be carried out in a microgravity environment.

TASK DESCRIPTION:

Glasses (primarily silicate based) that devitrify polymorphically by homogeneous nucleation are being studied

experimentally and by computer modeling. Lithium disilicate (Li_O.2SiOO is used for most calculations and

experimental measurements since the necessary kinetic and thermodynamic parameters are best known in that

system. Other glasses studied include soda-lime silicate (Na20.2CaO.3SiO2) and barium disilicate (BaO.2SiO2).

The computer modeling of glasses (primarily silicate-based ones) is done at Washington University. The silicate

glasses are prepared by Drs. C. Ray and D. Day of the University of Missouri, Rolla; they also study the

devitrification kinetics experimentally with differential thermal analysis (DTA). Transmission electron microscopy

(TEM) and DSC measurements are made at Washington University.

This research is a theoretical investigation of the nucleation and crystallization kinetics in glass torming systems.

The importance of nonsteady-state nucleation and viscosity in glass formation is being investigated. Methods are

being developed tot the calculation of nonsteady state crystallization using isothermal and non-isothermal annealing.

Calculations utilizing these methods on Li20-SiO2 and Na20-2Cao-3SiO2 will be performed, and several anomalous

experimental results that appear to contradict the theoretical calculations will be investigated and explained.

TASK SIGNIFICANCE;

The computer models describing nucleation and growth under isothermal and non-isothermal conditions by

simulating directly the evolution of the non-equilibrium cluster distribution will have wide applicability for phase

transtbrmation studies. In particular, they will allow real-time experiments of phase stability and transformation to

be carried out in a microgravity environment.

PROGRESSDURING FY1994:

During this past year, as part of the effort to make the computer modeling germane to phase transtbrmations under

realistic experimental conditions, the computer models were extended to model calorimetric data taken under

isothermal and nonisothermal conditions in heterogeneously nucleating systems and to take into account effects due

to finite particle sizes and surlace crystallization. The experimental measurements were made in collaboration with

Dr. C. S. Ray, University of Missouri, Rolla, MO.

1. Lithium disilicate glasses containing different, known amounts of Pt, a known nucleating agent, were prepared.

Nucleation rates were measured directly and compared with theoretical predictions. The first detailed measurements

of the transient time for heterogeneous nucleation were made and were/bund to agree with theoretical predictions

made earlier by us. Experimental differential thermal analysis (DTA) measurements were made of the crystallization

11-552
lI. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

of these glasses. An extension of our computer model tested earlier for homogeneously nucleating glasses was

found to predict correctly changes in DTA peak parameters (peak position, width and height) with Pt concentration

and DTA scan rate.

2. An effect of particle size on DTA peak parameters was established experimentally by us. SEM studies and DTA

peak profiles indicated a considerable contribution of surface crystallization. Our computer programs were modified

to take account of these effects by assuming random volume nucleation and growth and radial growth of a surface

shell into the particle. Simulations were shown to agree qualitatively with the experimental data, though

significant differences were noticed when the number of nuclei per particle became small. Ising-type lattice

calculations demonstrated that our analytical expressions gave better account of finite size effects than the start "dard

Johnson Mehl Avranu treatment, but failed when the number of nuclei became less than about five per particle (here

represented by the lattice). An approxtmate analytical solution was developed for all numbers of nuclei per particle.

Much better agreement was obtained with experunental data when this expression was incorporated into the

computer simulation.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: {3

PhD Students: 2

TASK INITIATION: 5/91 EXPIRATION: 5/94

PROJECT IDENTIFICATION: 962-26-08-07

NASA CONTRACT NO.: NAGS-873

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Kelton, K.F. Numerical model for isothermal and nonisothermal crystallization of liquids and glasses, J. Non-Cryst.

Solids, vol. 163. 283-296 (1993).

Presentations

Kelton, K.F. "Kinetics of phase transformations in glass forming systems." NASA Microgravity Materials Science

Conference. Huntsville, AL, May 24-25, 1994.

11-553
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

u o | I ao | ao o o o o ! a o o o o o ! a o; ! o oo I ! I | o ! a i Iii ! ! ! I u I u u o o a | o ! | oo | ! I o | I o | i u J i uI I o o o o o | a o o n o I I ao i u o i a _ n o; u I ou g o o ! o o 11 o o I o o o ao I o o I I o I a o i a o | oo o II o I o o o a o i nl o i ul ia i i n | i u i i ao io o u u o i u o I no I oo o a i i t i o i nl n a | | a o | a | o a o o o o o n ao oa o o I I o I n o i | a n uI o nln o i | u o I I I oI a o I o | I | | I a o

Compositional Dependence of Phase Formation and Stability

PRINCIPALINVESTIGATOR: Prof. Kenneth F. Kelton Washington University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objectives of this research are to extend computer models developed by us to model first order phase

transformations involving cases where the composition of the final phases are different from those of the initial

ones. This study is important to resolve conflicts in the experimental literature, to develop theoretical methods for

treating both steady state and time dependent nucleation in a partitioning system, to extend the understanding of

basic nucleation phenomenon, and to aid in the eventual development of techniques for making qualitative

predictions of desired phases and microstructures. This research will lead to improved methods/'or analyzing

thermoanalytic data that will have wide applicability for phase transformations studies. In particular, it will aid in

the design and data analysis of remote experiments, such as might take place in a microgravity environment.

Drop-tube experiments may reveal new effects of composition on the nucleation of related complex periodic and

quasiperiodic phases that will likely suggest future containerless solidification and microgravity studies.

TASK DESCRIPTION:

The steady state and time-dependent nucleation rates as a function of temperature and SiC 2 concentration will be

measured in one pseudo-binary silicate glass, Na_.O.CaO.3SiO2. Initial work by others suggests a strong

compositional dependence of the steady state nucleation rate, though the dependence of the transient behavior has

not been measured. The concentration dependence of the maximum undercooling in drop-tube experiments in

Ti-Mn-Si and AI-Cu-Co-Si, and if time permits, Ti-Cr-Si and Ti-Ni-Zr-Si, all metallic liquids that form

quasicrystals, will be measured. These data will be used to refine a model, developed previously by us, of the

magnitude and time dependence of the nucleation rate as a function of composition. That model for nucleation will

then be incorporated in our numerical model for phase transformations. Initial tests of that extended model will be

made by comparing calculated and measured trends of DSC data for the devitrification of Na20.CaO.3SiO2 glass as a

function of SiO2 concentration.

TASK SIGNIFICANCE:

This research is a theoretical and experimental investigation of the nucleation and crystallization kinetics in silicate

glasses and metallic alloys. The importance of partitioning on non-steady-state nucleation is being investigated. In

addition to enhancing the basic understanding of nucleation in such cases, new methods, based on computer

simulations, will be developed to analyze crystallization data under isothermal and nonisothermal conditions.

PROGRESSDURING FY 1994:

Funding for this project commenced in August, 1994 Since that time, samples of Ti-Cr-Si and Ti-Cr-Si-O have

been prepared and sent to Marshall Space Flight Center for drop-tube experiments. Samples of Na20.CaO.3SiO 2

glass are currently being prepared.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION: 962-26-08-14

NASA CONTRACT NO.: NCC8-049

RESPONSIBLECENTER: MSFC

l I I II lll | |l I I I I |le I I I | I IO III I | I I ! I Ill |! ll| ! III | II OItl II OI I I OI II I l I I I I I I I l I I II II I I I I I I Itl O II OII I II | I1| |II |! ! eI I eII | I 1411| I I$ | I0 ! I I II II | I Ill $I II I I I I! I l! I |11 DOIII !I I I I ! I I ! I el I|e ! |1 ! eI I|ll I I I II | I I ! I |1! | I! | I II I ! III I $11 III | II Ill l! ! l I! |1! l I1| III II $II I

11-554
Solutocapillary Convection Effects on Polymeric Membrane Morphology

PRINCIPAL INVESTIGATOR: Prof. William B. Krantz University of Colorado, Boulder

CO-INVESTIGATORS:

P. Todd

R. Owen

University of Colorado

Owen Re,arch

TASK OBJECTIVE:

• Design experiments tor casting polymeric membranes under low-g conditions to study the influence of

solutocapillary convection effects on membrane structure.

• Utilize the low-g environment provided by the KC-135 aircral't in order to conduct expenments to discriminate

between two hypotheses which have been advanced to explain macrovoid-pore formation in polymeric membranes.

• Modify and couple an exiting model developed lor the dry-cast membrane tbrmation process to a model for

macrovoid growth caused by solutocapillary convection.

TASK DESCRIPTION:

In order to study the influence of solutocapillary convection on polymeric membrane morphology and to

discriminate between the two hypotheses advanced to explain the growth of macrovoids in the dr),- and wet-cast

membrane-formation processes, the following tasks are identified:

1. Specification of membrane-casting solutions

2. Design and construction of the test cells

3. Perform ground-based control experiments

4. Carry out low-g experiments in KC-135 flights

5. Carry. out structural characterization of membranes

6. Moxlel development

TASK SIGNIFICANCE:

Polymeric membranes are used for a variety of purposes ranging from water purification to envm)lunental cleanup

of effluent streams. Membranes remove impurities because of submicroscopic pores. One problem in creating

submicroscopic pores in membranes is the propensity to form large pores or macrovoicks which "short-circuit" the

membrane's ability to separate dissolved impurities. Optimal means ti)r eliminating macrovoids have vet to be

developed owing to our lack of knowledge of what causes them. This research exploits the unique low-g

environment to discriminate between two hypotheses advanced to explain macrovoid formation. The results of this

research should enhance our ability to eliminate these undesirable detects during membrane manufacture.

PROGRESSDURINGFY 1994:

The following progress has been made in addressing the tasks listed above:

1. Specilication of the membrane-casting solution: The composition range of the casting solutions has been

determined within which macrovoid formation should occur. This has been established via model-based

experiments. A novel technique was developed to stabilize these casting solutions against premature phase

separation during the relatively long storage period prior to low-g flight experiments.

_n_n_e_u_n_i_i_e_iu_o_u_u_n_u_u_n_un_n_u_o_i_o_Inui_e_o_t_t_o_*_j_l_I_I_f_i_i_t_

1I-555
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

2. Design and construction of the test cells: A laboratory version of the test cell which closely resembles the

flight-test version has been built and tested in ground-based experiments to insure that it can reproducibly cast

ultrathin polymeric membranes under conditions in which macrovoids are observed. We also have successfully

adapted this cell with an optical probe which will permit us to observe membrane lormation in real time during the

low-g experiments. This real-time measurement capability for studying membrane formation in low-g is novel and

represents an added feature of these experiments which we did not anticipate in our original proposal to NASA.

This feature will make these experiments of even more value than originally anticipated. Construction of the flight

version of the test cell has begun.

3. Perform ground-based control experiments: We have chosen the cellulose acetate/acetone/water system as the

casting solution from which our membranes will be formed. The test cell described above has been used to cast

uniform reproducibly uniform-thickness membranes from these casting solutions in ground-based experiments. The

resulting membrane structure has been studied using scanning electron microscopy (SEM), and macrovoicLs have

been observed.

4. Carry out low-g experiments: The low-g flight experiments planned for the second half of year 1 have been

booked for February of 1995, which is the tenth month of this project. Dr. Owen has provided consultation on the

design of the flight experiments. Mr. Konagurthu, a chemical engineering student studying tbr his M.S. degree, is

becoming qualified for flight via arrangements made through Marshall Space Flight Center.

5. Carry out structural characterization of membranes: Approximately 30 to 40 membranes cast via our

ground-based experiments have been studied via SEM. The digital images form these SEM studies have been stored

for comparison to those obtained from the membranes cast in low-g and the corresponding controls.

6. Model development: A coupled heat- and mass-transfer model for the evaporative casting of cellulose acetate

membranes has been modified to properly describe the casting conditions of the special test cell we have designed

and constructed for these experiments. This model has been used to determine the composition range of the casting

solutions within which macrovoid formation might be anticipated. This model also has been used to design the

capacity of the individual test cells in order to insure that the membranes can be completely lormed during the 25 or

so seconds of low-g time available in the flight experiments.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

PROJECT IDENTIFICATION:962-26-08-15

NASA CONTRACT NO.:NAG8-1062

RESPONSIBLECENTER: MSFC

i i i 11 o I I I I an i a i i I I I I I s i iI o Ii i i i i i I I I I I II I i a i i i I o I o o Io I I i i I I i i I i I oI a a I I I I I I I el I I eo III Ill l I I o I 11 III II I I I I o I I o I I o JI l II a I I I I I a I Ia II I I I I I I a I II II I I o I i I I I I I o I Ia Ii a i i I i i I o I i i I II II I I I I I I I I I o I II iil i i t i i i i iI I II ¢ I I I I I o I II Ill I I o I i o o II I II I I I t a l I I oa i i a i i i i ei i

II-5 5 6
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

H IIIIIIJlllll I I I I ; I I I JJIIH I I I ; Ill J8 ill J Itlll_ I I I J I I I I Jill Iill J I I J J I I I J JI I ill I IHIII I IIII I J Illbllll1611 H I IIIHlll I I J III I I I I I II II III IJ III III I Jl I IH I tJ I Jl I I_11_ I Jtll11101 i III I I I IlJll I I J I llllll J IJill t lilt I I H IH 11 lllHI I llll I I I I I IIIIII I IIIII I II I

Contaitlerh,ss Property Measurement (!/ Hiy, h-Temperature Liquids

PRINCIPALINVESTIGATOR: Dr. Shankar Krishnan Containerless Research. Inc.

GO-INVESTIGATORS:

P.C. Nordine Contalnerless Research, Inc.

TASK OBJECTIVE:

The task objective is to measure the optical properues of high-purity liquid metals and alloys (AI, Zr, Ni, and Ni-Zr

alloys) over wide wavelength (220-1100 nm), temperature (Tin + 300 K), and composition ranges under

containerless conditions. Spectroscopic, pulse(1 dye-laser ellipsometry is used to obtain lhe complex dielectric

functions and spectral emissivity data at high temperatures on clean liquids using electromagnetic levilation. These

data are ueeded for accurate noncolllaCl temperature measurement, and for measurements of d_e total hemispherical

cmillancc by integration of emissivity over the wavelength range of thermal emission.

Another major outcome of Ihis research will be the determination of the optical properties of liquids over a wide

wavelength range. These measurements are of fundamental imporlance R) advancing lhe lheoiy of liquid metals. For

example the presence or absence of imlx)rtant interband transitions provides information on dm valence, bonding,

ioinl densily-of-.stales, and the exlen! lo which nearly-free electron behavior is exhibiled by liquid metals and alloys.

TASK DESCRIPTION:

The research approach is Io levitate liquid inelals and "alloys (AI, Ni, Zr, and Ni-Zr alh)ys) eleclminaguetically and

use atspecm)scopic pulsed dye-laser ellipsomeler to measure the complex dielectric fimction and the spectral

clnissivily ill the wavelength range 22()-1100 nm. Pulsed radiation is generated by a Moleclmn dye-laser, and the

wavelenglh ix automalically sol and adiusled by a latx_ratory computer. Light reflected by the st)ecimen ix collected

and aualyzed by a u]lique rolatmg analyzer ellipsometer.

The rotalulg compollenl>_ of the ellipsometcr are motorized and controlled by the computer. The signals ark detecled

by a pair of pholodiodes and an EG&G boxcar averager is used to extract the mean value of the light intensities at

the Iwo pholodiodes which receive the orlhogonally polarized components of the reflected lighl. The signals are

automatically measured by the computer.

A Molectron (lye laser is used to generate pulsed radiation in the 220-1100 nm wavelength range. The light is

steered through several mirrors, and transmitted through a pair of Glan Thomson linear polarizers. The second

polarizer ix fixed m azimuth, and rotation of the first polarizer "allows light levels to be adjusted to the optimum

rallies. The light is incident on the liquid specimens at a fixed incident polarization, and the reflected polarization is

_malyzed for its new azimuth and etliplicity.

A modilied rotaling analyzer ellipsomeler is used to measure the outgoing polarizauon at 6 azimufl_s of the

analyzer. The analyzer is of the beamsplitting type such that the two orthogona.l components of the beam are

simultaneously obtained. Three mtensily ratios are measured at three independent pairs of azimuths. The complex

dielectric conslanl, radices of refraction, aud spectral emissivities are derived from standard equations. The light

intensities are detecled by a pair of high speed, UV-enhanced silicon photodiodes and measured by a pair of gated

illtegralt_rs.

The empluLsis of measurements on liquid metals and "alloys is to determine the temperature and (for alloys)

composilion dependence of 'all optical properties over the accessible wavelength range. Measuremenls are possible

from approximately 0.8 of the melting temperature, (Tm) in undercooled liquids to at leasl 3tglK above Tin. The

observed effects of temperature and composition on optical properties and the wavelm_gth dependence of these

properties are interpreted in terms of liquid structure and bonding.

I1-557
Theliquid nickel, zirconium, and their 'alloys have been chosen to be investigated in this research because they

display unique glass forming behavior, typify early and late transition metals, and because they are also of interest

to other NASA investigators. Measurements at 633 nm on these metals is being conducted in collaboration with

Professors Bayuzick of Vanderbilt University and Johnson of the Calflornia Institute of Technology.

TASK SIGNIFICANCE:

The relevance and significance to the microgravity program are twofold. First, the spectral emissivity and total

hemispherical emissivity form the basis for new noncontact thermophysical property measurements in microgravity

experimentation. For example, knowledge of total hemispherical emittance allows heat capacity and thermal

diffusivity to be accurately determined from li'ee-cooling and pulse-heating experiments. Spectral emissivity data

'allow true specimen temperatures to be determined using optical pyrometry. Second, spectral emissivity

measurements on specific materials are needed by other NASA investigators in ground-based and microgravity

experimentation.

PROGRESSDURINGFY 1994:

Work in the past year included spectral emissivity and infrared radiometric measurements on materrals nvestigated

on the TEMPUS flight experiment flown on the IML-2 mission. It allows the PI's to convert infrared radiance

data obtained in the flight experiments to true specimen temperatures. The results of the work are summarized in a

report to the TEMPUS PI's and to NASA. The conclusion of the report addresses the key issue of the need to

cross-calibrate the laboratory and flight infrared radiometers. Following is the title and executive summary of this

report. Part of the work has overlapped into FY 1995 funding period.

Spectral Emissivities and Temperature Measurements: Liquid Zr, Ni, Ni-25% Sn, Ni-32.5%

Sn, Ni-40% Nb, and Ni-75% Zr

This work was conducted in support of the PI requirements Ibr the TEMPUS flight experiment on IML-2. This

report provides: (i) values of the spectral emissivities at 1= 633 nm for liquid Zr. Ni, Ni-25%Sn, Ni-32.5%Sn,

Ni-40%Nb, and Ni-75%Zr over a wide temperature range including undercooled and superheated conditions, (ii)

experimentally determined spectral emissivity functions at I = 633 nm of the radiance temperature measured at 1=

650 nm, which allow conversion of TEMPUS flight data to true temperature using the silicon-based flight

pyrometer (SIP), (iii) experimentally determined functions that allow conversion of infrared radiance (1-2.5 tam

ban@ass, ZPY-channel 1 on TEMPUS) data to true temperature, (iv) assessments of the total temperature errors,

and (v) an analysis of the temperature measurement system. Pulsed-dye laser ellipsometry was conducted at I = 633

nm on electromagnetically levitated liquid metals and the radiance temperatures of the specimens were recorded using

three pyrometers. Two of these pyrometers had an operating wavelength near 650 nm. The third pyrometer (LM)

was developed by Heimann Optoelectronics GMBH and had a nominal operating wavelength range of 1-2.5 lain.

This pyrometer was constructed to be similar to the flight model (FM) and developmental model (DM), but

exhibited significant differences from these pyrometers in its spectral sensitivity function. Most of the materials

studied exhibited moderate temperature dependence of the optical properties and emissivities. Only nickel and

zirconium could be undercooled significantly in our apparatus. Cross calibration of the LM and DM pyrometers will

be needed, using the specimens of interest as the radiation source in order to interpret temperature measurements on

TEMPUS in a manner that is traceable to a primary temperature standard. The infrared and 0.633 pan emissivities of

the materials were consistent with the behavior of a typical metal such as tungsten. A sensitivity analysis is

presented using the actual wavelength dependence of emissivity tor tungsten (over the bandpass of the LM and DM

pyrometers) which showed that significant errors will remam if the present LM results were applied to correct

apparent temperature measurements obtained on TEMPUS for emissivity effects. A direct comparison of the LM

and DM pyrometers using a special tungsten strip lamp is recommended.

I I II I I I I I I I I It l I I I II II I I I I I I I I II I IQI I I I I I I I I I I II OI I I I I I I I I II OI I t i i t i i I I i Ii i i i i i i i i, I i i ii i I I i i i i I ii i Ii ! III I II I i i iI i ii i i i i I I I I Ii i i ii i i ii i i i i i I i I I i i ii i Ii i i I i I I i i oi i ii i i i ii i i ii i ii i ii ii I I I I I I ii i i i i i i ii I ii I ii i i i i I I i i i ii i i I I i i i i i I II I I i i I I I i i i iI i I I I I I I

I1-558
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 5/92 EXPIRATION: 5/95

PROJECT IDENTIFICATION: 963-25-07-05

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

,Journals

Krishnan. S., and P.C. Nordine. '*Optical properties of liquid aluminum in the energy range 1.2-3.5 eV'. Phys. Rev. B.

47. 11780-11787 (1993).

Krishnan. S., and P.C. Nordine. "Analysis of the optical properties of liquid aluminum". Phys. Rev. B, 48, 4130-31

(t993).

Krishnan, S., C.D. Anderson and P.C. Nordine. "The optical properties of liquid and solid zirconium". Phys. Rev. B, 49,

3161-3166 (1994).

Krishnan. S., C.D. Anderson. J.K.R. Weber, P.C. Nordine. W.H. Hofmeister, and R.J. Bayuzick. "Optical properties and

spectral emissivities at 632.8 nm in the titanium-aluminum system". Metall. Trans, 24A, 67-72 (1993).

Krishnan, S., J.K.R. Weber, C.D. Anderson, P.C. Nordine, and R.I. Sheldon. "Spectral emissivity and optical properties

at k = 632.8 nm lor liquid uranium and zirconium at high temperatures". J. Nucl. Mater, 203, 112-121 (1993).

NASA Tech Briefs

Krishnan. S. and P. C. Nordine. Spectral emissivities and temperature measurements: Liquid Zr, Ni, Ni-25%Sn,

Ni-32.5%Sn, Ni-40%Nb, and Ni-75%Zr, CRI Report to NASA MSAD. NASA Tech Brief, ( April 8, 1994).

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II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

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Noise and Dynamical Pattern Selection zn Solidification

PRINCIPALINVESTIGATOR:Prof. Douglas A. Kurtze North Dakota State University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

To understand the fundamental mechanisms by which a pattern-forming system can change the spacing of its

pattern, and to devise a means of calculating the preferred spacing to which external noise will drive the pattern.

TASK DESCRIPTION:

Numerical computation of the time evolution o1 mathematical models of solidification fronts, and analytical

arguments to extract the preferred spacing from the model equations.

TASK SIGNIFICANCE:

Properties of materials grown from the melt are largely determined by their microstructure, which in turn is

strongly alfected by the front shape durmg solidification. This research will establish whether processing in a noisy

environment (such as the Space Shuttle) can lead to more reproducible, and hence better controlled, front shapes

than processing in a quieter environment. This study will definitively enhance our understanding of the

fundamentals of solidification. A more complete study (such &s this) is required for the design of materials with

specific materials properties; a difficult task, but an unportant practical goal.

PROGRESSDURING FY1994:

As of September, 1994, this grant has not yet been received. Nonetheless,it is possible, using older computer

equipment, to run some of the smaller and simpler simulations involving perturbations of patterns governed by the

Swift-Hohenberg equation and similar simplified, one-dimensional evolution equations.

An undergraduate research assistant, Jed Overmann, has been hired to work on this project. An incoming fieshman,

he is funded by the Science Bound program run ASEND, which administers the NSF EPSCoR grant to North

Dakota. Before arriving, Jed had decided that his interests had changed and that he would prefer to work on some

biological project. Thus he may notcontinue working on this project Ibr the lull academic year. However, he has

continued working on it while seeking an appropriate and interesting project elsewhere, and his work has proven

quite helpful.

I have written code to generate perturbed initial patterns for theSwift-Hohenberg equation and to integrate the

evolution equation torwardm time. Preliminary results indicate that perturbations to the amplitude of a cellular

pattern are surprisingly ineffective at causing changes in the wave number of the pattern. Perturbations to the phase

of the pattern are much more effective. For initial wave numbers which are well below the expected preferred wave

number, we find that these perturbations do preferentially increase the wave number. We are currently working on

quantifying and systematising these results, and continuing to search through different initial wave numbers.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 0

TASK INITIATION: 10/94 EXPIRATION: 10/96

PROJECT IDENTIFICATION: 962-25-05-30

NASA CONTRACTNO.:NAG3-1603

RESPONSIBLECENTER: LeRC

i i I II III i II I l I II I i I II II I I I I I II i I I I II I I I II I ii I i ii I II I I i I | I I I II I I I I I I I I I I II I I I I I l lll I I I III I Ill III II I III I II I l I II I II I II II II II I n III iIll II I III I II I III I I I III I I II I I I I lI II I l I If Ill II I I II I III I II I|I I If III Ill Ill III l lI I Ill I I I II III III II I II I I I IIII IIIIIIII III I I

II-560
li. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

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Chemical Vapor Deposition of High T_Superconducting Films in a Microgravity Environment

PRINCIPALINVESTIGATOR:Prof. Moises Levy University of Wisconsin, Milwaukee

CO-INVESTIGATORS:

B. Sarma University of Wisconsin

TASK OBJECTIVE:

The basic goal of this research is to grow and process single-crystal, high-temperature superconducting thin films

under microgravity conditions.

TASK DESCRIPTION:

Superconducting thin films will be grown by chemical vapor deposition in three different transport reactors in order

to investigate the effects of gravitationally-induced convection currents on the superconducting characteristics of the

films. Different orientations with respect to gravity will be used.

TASK SIGNIFICANCE:

It is believed that microgravity will allow tor unique growth conditions for vapor-phase transport and for the

formation of single crystalline materials during postprocessing to the superconducting phase.

PROGRESSDURING FY 1994:

A compact chemical vapor deposition MOCVD system with a single organometallic precursor was designed, built

and tested. A model for the vaporization and mass transport of mixed organometallics from a single source for thin

film MOCVD was developed. It was shown that a stoichiometric gas phase can be obtained from a mixture of the

organometallics in the desired mole ratios, in spite of differences in the volatilities of the individual precursor

compounds. Proper composition and growth rate can be obtained by insuring that the organometallics are

completely sublimed after the slotted borosilicate tube containing the compacted mixed organometallics has

traversed the short heating zone of the vaporizer. Y_Ba_Cu307 superconducting films with T¢'s around 90K were

obtained on [ 100l Y stabilized cubic zirconia and [100] MgO substrates. Under ideal conditions the high Tc films

were oriented with the c-axis perpendicular to the substrate plane. This is the preferred orientation tot achieving

large current densities in the plane of the film. The pressure of the argon carrier gas was between 5 and 7 torr and

that of the oxygen gas was also within this range. The combined flow rate was between 200 and 400 standard cubic

centimeter per minute.

The compact MOCVD system may be rotated in order to determine the effect of gravitational fields on the growth

behavior of the high Tc superconducting films. In the first orientation investigated, the compacted precursor

vaporizer tube was moved downward through the heating zone and the heated substrate was held upside down in the

reactor arm of the U shaped system. Thus the gas flow rate past the reactor was against the gravitational field. It

was lound that the central part of the circular film was about 250 nm thinner than the outer part for a 1000 nm

average thickness film. Thus fluid hydrodynamics affected the diffusion controlled growth rate of the films even at

the low pressures of the MOCVD system. A microgravity environment may allow the use of lower gas flow

velocities thus making the diffusion controlled growth rate process more uniform along the diameter of the films.

Two other configurations of the MOCVD system with respect to the gravitational field are being investigated.

I I I oI aoI I oI oI I I aoI I oooII I I OIlOI ao|o oolo II oI I oIII I I IoI oI I oI I I I oII I l I ooI ol l i oi i ooooii i ooa oI! ool ooI OI 0¢ Dol I laI I ooooaO|l oloo i ioi i oOOllOl oooo i ioOOlOiOO i oo i io lgo oI OI oo ! I! i iI noi ooao I I Oooi I Io II llO ¿O01 OaoOil I I IIOOO IOI oooo I OI I OOoIOI OOI I ooOl I oi ioi i oi i ool i

11-561
lI. MSAD Program Tasks m Ground-based Research Discipline: Materials Science

i| | i |¢te Ii¢ |o I | I I o |11 J o I I t I Io i i I ! o I I | I I I | II * | iJ J i i | i I ¢ | J I I I I I I i i i i ia iii I 141111 _ I¢ mI J i ! I i I J J i sis i ii | i i i I I ¢ I 1811 o | I I | i ¢II mI! _ 61 ! ¢ I I I I s I | I | | I II I _ ! I I | i | i | I I I I Ji. ii s i I I I I I | I I |_ I I _ I | I, I I I i tI I II I s I I s ! I IJ _ I o _ I o I _ I | I I| _ I _ II sl I e i| i I II I I I |11 _ I I e I ! ! | I| | I I I

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/91 EXPIRATION: 6/94

BS Students: 0 PROJECT IDENTIFICATION: 962-26..05-07

MS Students: 0 NASA CONTRACT NO,:NAG3-1274

PhD Students: 1 RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Meng,G., G.Zhou, R.L. Schneider, B.K. Sarma, and M. Levy, Mechanism of mass transport of mixed power precursors for

MOCVD of HTSC and relevant materials. Appl Phys. Lett, 63. 1981-1983, (1993).

Zhou, Gang, Guangyao Meng, Roger L. Schneider, Bimal K. Sarma, and Moises Levy, Vaporization of a mized Precursor in

chemical vapor deposition of YBCO films. Journal of Superconductivity, Vol.7, 135-237 (1994).

iIIII IiiiiiIIl iIIIiiII III iiliil IiI III uIi IIIIIIIII IIiiIIIiIIIiiiiiIII iiiIIIIII III IIIIiIIOlI iIIIIIiiIII III IIIIIIIII III III IIIIiil iiIIll IIII IIIiii iiiiiiiIlie IIIIIIII III IIIl IeIIIIIiiiiiiiiiIIIII IIIIIIllOIl! iiiiiiIIIIII IIlII iiiIIIII iiiiiiIIIIIi IIi Ii

I1-562
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

Ill I III II III lilt III I I leo III i iiii IIi ii iii t I I i I Ii i I I lie I I IIIII I I I I I II I II I III III IIIII I I I I II I II IIIi Iii IIIII II I lltllllllllllll III I llll Ill III I I Iit l a I I II Ill II Oil n i I I I I IIi U lie II I IIIllll I IIIllllllllllllllllllllllll I IIIIIIIIIIIIIIIlUlIIIIIIUlIIIIIIII

Microstructural Development during Directional Solidification of Peritectic Alloys

PRINCIPALINVESTIGATOR:Dr. Thomas A. Lograsso Iowa State University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The mechanisms of and conditions required for the tbrmation of peritectic solid dendrites, cells, or planar growth

between the primary solid dendrites or cells and the transitions between these structures will be investigated. In

addition, alternating bands of solid phases perpendicular to the growth direction have been observed in peritectic

systems. However, the precise conditions under which these bands form and the mechanisms by which these bands

form are not clearly understood. It has been postulated that the development of these different structures is related to

changes in the composition of the liquid. A model will be developed that will predict the compositional variations

that occur in the liquid under the assumption of no convection. This model will be compared to experimental

results to evaluate the importance of convective efrects on the formation of various structural characteristics.

TASK DESCRIPTION:

This research will focus on:

1. Establishing the growth conditions in terms of temperature gradient and growth rate for the formation of planar,

cellular, and dendritic growth of the peritectic solid in a two-phase peritectic under convection-free conditions, with

an emphasis on the morphological transition from cellular front primary and planar front peritectic solid to single

phase planar front solid; and

2. Determining the effect of convection-free conditions on the lbrmation of a banded structure during directional

solidification of a two-phase peritectic alloy.

The research approach is to initially focus on two alloy systems, In-Sn and Sn-Cd. In-Sn has a very low peritectic

temperature, which allows tot the possibility of direct observation during solidification. In addition. In and Sn have

essentially equal densities in the liquid state in the temperature range of interest, which should minimize

density-driven convection. In the Sn-Cd system, the solute element (Cd) is more dense in the liquid state, which

should minimize density-driven convection when solidification occurs upward. This system has been well

characterized and is more tractable in terms of sample preparation than In-Sn. These results can be compared to

previous work on the Pb-Bi system, in which the solute element (Bi) is less dense and thus provides a driving force

for mixing in the liquid through convection.

TASK SIGNIFICANCE:

This research effort will establish the ground-based data required for the identification of the appropriate alloy

system, composition, and growth conditions for microgravity processing. Studying solidification for these types of

systems is important, because a number of industrially significant materials solidify in a similar manner such as

brass, bronze, some steels and high temperature superconductors. The utilization of a microgravity environment

greatly facilitates the analysis and modeling of data, since gravity-induced mixing in the liquid can strongly affect

the solidification process.

I, I I, II I I I I I I I I I I I I I I I I II I I I II I I I I II I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I II I I I I II I Itl II I I I I I I I I II II I I I I I I I I I I I I I I I I I I U I I I I I I I I I I I I I I I I I I I II I I I I I II I I I II I I I II I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I I I I II I I

11-563
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

PROGRESSDURINGFY1994:

The research effort has been concentrated in the/ollowing three areas.

1. The ln-Sn phase diagram has been redetermined using thermal analysis in the region of the peritectic reaction.

The composition range along the peritectic isotherm was found to be significantly more narrow than in currently

published phase diagrams. Alloy compositions necessary to produce the microstructures of interest will be selected

on the basis of this information.

2. Initial experiments have been conducted using Sn-Cd alloys to correlate microstructural development and inter/ace

morphology to growth conditions. The fraction solidified at the point of quenching will be varied to check the

possible extent of convective effects.

3. A model has been developed to describe the/ormation of banded microslructures. Experimental results will be

used to evaluate its predictions.

STUDENTSFUNDED UNDER RESEARCH: TASKINITIATION: 7/93 EXPIRATION: 7/96

PROJECTIDENTIFICATION:962-25-08-28

NASA CONTRACTNO.: NAG8-963

RESPONSIBLECENTER: MSFC

l I * Ill I I * I I Il I Iel I I l l l * l I * l I* l I * l I I I I I I Ill II I I I I I I I I II I I I I I I I I I I II I I I I I I I I I I I I I Ill I II I II I I I I II I n I nl i I i i i i i i i i ii iiI I I I i i i i I II II I i i i ill I II I Ii i i I i i i i i i i i iI II i I ! i i i i i I i I Ii i i i i i i i I ! I iI I II i I i I i i i i i i I ii i ii i i i ill I I I I II I I I I I I I I II II I I I I I I I I II I I I i I I I I II

II-564
Numerical Investigation qf Thermal Creep and Thermal Stress Effects in Microgravity Physical

Vapor Transport

PRINCIPALINVESTIGATOR: Dr. Daniel W. Mackowski Auburn University

CO-INVESTIGATORS:

R. Knight Aubum University

TASK OBJECTIVE:

The objective of this research is to quantitatively predict the roles of thermal creep and thermal stress on

microgravity physical vapor transport through detailed nmnerical calculations.

TASK DESCRIPTION:

The research will formulate thermal creep and stress effects into a variable property., two-dimensional representation

of heat and mass transfer in cylindrical ampoules under typical operating parameters. Physical conditions at which

thermal creep and stress significantly "alter vapor transport from a pure diffusion-limited mode, as well as the

resulting eflects upon mass transfer rates and mass flux uniformity at the crystal surfacei will be determined. The

research will benefit the prediction and development of microgravtty crystal growth technology by providing, for the

first time, an accurate accounting of "allrelevant physical vapor transport mechanisms.

The potential for growing high-quality crystals in closed, cylindrical ampoules using chemical vapor transport and

physical vapor transport processes under microgravity conditions has been demonstrated in a number of

experiments. The development of this technology will require an accurate modeling of the relevant vapor transport

mechanisms occurring in buoyancy-free environments. Previous numerical efforts to predict microgravity crystal

growth rates have employed a diffusion-limited formulation of vapor transport. However, theoretical arguments

strongly indicate that the non-isotherm',d conditions encountered in arnpoules can lead to an appreciable motion of

the bulk fluid as a result of previously unrecognized phenomena. Temperature gradients tangential to the ampoule

side walls can, through the mechanism of thermal creep, drive a slip flow of gas over the surface. In addition,

temperature gradients within the gas itself can induce a fluid stress, and resulting fluid motion, through the

mechanism of thermal stress. Order-of magnitude estimates suggest that, under typical ampoule conditions, the

fluid velocities resulting flom thermal creep and thermal stress can be comparable to vapor diffusion velocities.

Specific tasks include:

• Develop code for numerically solving governing differentiad equations. Assemble thermodynamic and transport

property database of commonly used PVT samples and carrier gases.

• Perform numerical calculations of diffusion-buoyant convection vapor transport in the absence of thermal creep

and thermal stress. Check numerical results with previously published results.

• Incorporate thermal creep boun 'dary conditions and thermal stress constituitive law into numerical code.

Determine model parameter values at which thermal effects significantly alter vapor transport from diffusion and

buoyant convection predictions.

• Determine the individual effects of thermal creep and thermal stress on vapor mass transport rates and the

uniformity of mass flux at the crystal surface. Based on numeric',d results, develop rational expressions for

estimating the relative contributions of the thermal vapor transport mechanisms to mass flux as a function of

ampoule, sample, and carrier parameters.

TASK SIGNIFICANCE:

Under earthbound conditions, heat and mass transfer within nonisothermal physical vapor transport (PVT) crystal

growth ampoules will often be dominated by buoyant convection. The rationale for performing PVT experiments

in microgravity conditions is that the buoyant convective mechanisms will be suppressed, and crystal growth will

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II-565
occur in a diffusion-limited mode. However, qualitative arguments indicate that the convective mechanisms of

thermal creep and thermal stress, which are usually negligible in comparison to buoyant convection in earthbound

environments, could significantly effect mass transfer rates in microgravity PVT systems. A quantitative

understanding of the role of these mechanisms in microgravity PVT crystal growth processes requires detailed

numerical modelling.

PROGRESSDURING FY1994:

Our eftorts during this period focussed on the development of a code for modelling mass, momentum, and energy

transfer in binary PVT systems. Unlike previous modelling efforts, the code is based on a transient formulation.

Begining with a specified initial equilibrium condition within the PVT ampoule, the boundary, conditions at the

nutrient source end are changed to prescribed operating conditions over a fixed length of time (which corresponds to

raising the source temperature and nutrient partial pressure to their steady-state values). The evolution of the

nutrient mass fraction, temperature, and velocity fields within the ampoule are determined by a semi-implicit time

integration scheme for the energy, species, continuity, and momentum equations. We have tbund that the transient

approach actually leads to a more efficient and reliable determination of the steady-state condition than can be

obtained from direct solution of the steady-state condition.

We have used the model to further examine the effects of thermal creep on mass transfer rates and uniformity in

binary PVT systems. We have specifically examined a system representing the Copper Phthalocyanine (CuPc)

PVT experiments performed by Debe et al., for which the temperature drop across the ampoule had the relatively

large value of DT = 673-343 = 330 K over a length of 8.5 cm. The partial pressure of the nutrient (CuPc) in this

experiment was 'also at a trace level compared to the background gas. In the absence of thermal creep, the predicted

maximum flow velocity within the ampoule (resulting from Stefan flow) was on the order of 0.5 mm/s. Including

thermal creep in the boundary conditions resulted in a maximum velocity of 15 ends. Although the differences in

calculated velocities with and without creep are protound, we found that the net rate of mass transfer at the crystal

was increased by less that 5% with the inclusion of creep. The uniformity of mass flux at the crystal, however, was

significantly altered by creep. For the pure diffusion case the flux at the crystal was essentially unilbrm. Including

creep, on the other hand, resulted in a 50% change in mass flux from the ampoule centerline to the side walls.

Further examination of thermal creep in _g PVT systems indicates that a critical factor is not necessarily the

absolute change in temperature across the ampoule, but rather the local magnitude of the axial gradient of the wall

temperature. Because the transition from the furnace 'hot' zone to the 'cold' zone can occur in a relatively small

length, the axial temperature gradient in PVT systems can be locally high even in situations where the overall

change in temperature across the ampoule is not appreciably large. Our predictions indicate that thermal creep can

result in strong, locally-recirculating flows at the hot to cold transition point. If the transition point occurs in the

viscinity of the crystal substrate, the creepinduced flows can appreciably alter the unilbrmity of growth.

We are currently modit'ying the code to include the effect of thermal stress, which arises from the contribution of the

Bumett terms in the fluid stress tensor. We are also examining the effects of 'g-jitter' on the growth rates and

patterns within the ampoule. Future work will focus on methods of allowing the crystal interlace to become

non-planar during the growth process, from which the stability of the interface can be deduced.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 0

TASK INITIATION: 6/93 EXPIRATION: 6/95

PROJECTIDENT_V_CAT_ON: 962-21-08-18

NASACONraACTNO.: NAG8-977

RESPONSIBLECENTER: MSFC

|_|||_|_||_||_||_!_!_||_||_!_|_||_|_|_|_!_|_!!e|_|||_|_e_!!_|_!_||_||_e_||!_||_|||_|_|_||_|_|_!_!_e_|_!e||e_|_|!_!_|_|_|_|_|_!_|_|_|_||

I1-566
BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Mackowski, D.W., and Knight. RW, "Numerical modelling of physical vapor transport under microgravity conditions:

effect of thermal creep and stress." Proceedings of the Microgravity Studies of Organic and Polymeric Materials

Workshop, D.O. Frazier and CE. Moore. eds.. NASA Conference Publication 3250, 17-20 (1994).

Presentations

Mackowski. D.W.. Knight, R.W.. Rao, V.R.. and Walker. D.G. "Numerical Investigation of thermal creep and thermal

stress effects on microgravity physical vapor transport." NASA MSAD Microgravity Materials Science Conference.

Huntsville. AL, May, 1994.

Walker, D.G.. Mackowski, D.W.. and Knight, R.W. "The effects of thermal creep on physical vapor transport under

microgravity conditions." AIAA 32nd Aerospace Sciences Meeting, paper no. 94-0567. Reno. NV. January 10-13, 1994.

Ilt|l|t!el||t tlltlttt!l|!!|l!ll!lltllS|t!|ttlll|ll0tl||t tt!lS|ltlltll0tltll!tlell|tt t!lt!t t|ltllt lit ¢ltttt|t |!l||l|ll|tlt|lllltll||lltl!0|lllt It t II |le|l|lt ||t Itlt0ll|tl0|lltlt t|t ISll0l!0!lS||lll||t I¢lt!t lit It lit tt|t |t t t|t |t t |!t |t t It Ittlt 0lit|it

II-567
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

llll|ll|l|*llll*ll .*lllllllH|llllll..I.IIIIl*llllll|ll*ll**l.*l*l=.l.l|lll=ll||D"l"l.l|lll*ll*|Mt" .II|I.I|SI! _l;_|l"|lHUl.l.ll*ll'l"llll'H*lM*|ll*ll*lll|lHIHIl|01"llOlll" I. "IU H*IHIIIIII.* .I H IlU|IIIIHIH.I"

Polymerizations in Microgravity: Traveling Fronts, Dispersions, Diffusion and Copolymerizations

PRINCIPALINVESTIGATOR:Prof. Lon J. Manias University of Southern Mississippi

CO-INVESTIGATORS:

R. Lockhead

J. Pojman

University of Southern Mississippi

University of Southern Mississippi

TASK OBJECTIVE:

Polymerization studies of bulk-phase diffusion and polymerization in monomer and conomer mixtures or in

monomer droplets in a non-solvent are being performed to study density effects on polymerization.

TASK DESCRIPTION:

These experiments will allow determination of fundamental monomer and polymer properties. The diffusion rate

constants to be measured in the absence of convective mixing have not been accurately measurable on earth. This

data will provide new insights into the fundamental behavior of polymers in a variety of situations important to

their formation and processing. For example, molecular weighls and distributions are directly dependent on the

relative diffusion behavior of monomers and polymers. Processing of polymers, either in solution or from the

melt, involves molecular reorganization and motion. The combination of convective mixing with diffusion

determines the ability of polymers to effectively orient into crystalline domains. A further example is provided by

copolymerizations at high conversion. In this regime, which is industrially important on Ea_rth, the diffusion

constants of monomers and polymers become extremely important. The copolymer composition throughout the

reaction must be amenable to calculation and prediction. This is currently not possible without accurate knowledge

of polymer and monomer diffusion constants.

Three separate but closely related research investigations are being conducted that all deal with developing a

fundamental understanding of monomer and polymer dilfusion during polymerizauon or processing under widely

different conditions, and with applying this knowledge to the formation of unique materials. The three projects all

involve bulk-phase diffusion and polymerization in neat monomer or comonomer mixtures, or in monomer droplets

dispersed in nonsolvent. All three deal with diffusion effects that should uniquely manifest themselves under

microgravity where analysis by optical, interference and light scattering will give complete understanding of

macroscopic down to molecular level behavior.

TASK SIGNIFICANCE:

Microgravity oilers a unique environment for studying polymer diffusion and polymer polymerization reactions.

The absence of convection currents, which are the major mode of mixing at the molecular level on earth, are

eliminated or reduced in the microgravity environment. More importantly, the prediction of unique copolymer

composition development in microgravity will allow controlled formation of new compositions of matter. The

absence of mixing at the molecular level should produce unique short-block copolymers available for the first time

for comonomer compositions which normally lead to random or long-block copolymers under good mixing.

PROGRESSDURING FY 1994:

The opportunities for flying KC-135 and shuttle flight experiments are most exciting. They can immediately

provide us with supporting results for the types of effects gravity are expected to have on several fundamental

polymerization and phase separation processes. We will pursue possible KC-135 flight experiments with Jan

Rogers on photomitiated radical and cationic polymerizations of single and multicomponent materials. The former

will serve as references and the latter will evaluate the effect of microgravity on phase separation during

simultaneous polymerization of two miscible monomers that give immiscible polymers: kinetics of

polymerization, demixing and aggregation. These experiments will be included in the shuttle experiments along

with several additional systems testing spinodal decomposition of polymers dissolved in monomer solutions that

undergo polymerization to give immiscible mixtures.

__e____*_*_*_*_*__*___*_
If. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

i_. a *, a o | a, | a, o, i o |, o o t |, i ii i ill a o | a o o * o o I Ia IJ o | a, o o o, t |, t i,, o,,,., o,, I,,,,,,, ! J o, a. i, o o * o o o, o a * o, o |, o o a o o o i o i uo o a, o * o o I a o i o,, i, o _ | o! o | o, * | nl * Da. ! * | o, a o o |, o o | o * o, oi o * a, ma o o o, i a* u ao,, *,,, | o,, o * a,, a* o a,, i a. _ * a o o a o o _ a. n a o | a, _ _ i o i a, i,, ia o |, o t o _, o a,

Our work on steric stabilization of oil/water systems has progressed with hydrophobically-modified hydrophilic

polymers.

• Hydrophobically-modified poly(acrylic acid) is an effective steric stabilizer for oil-in-water emulsions, whereas

hydrophobically-modified hydroxyethylcelluose seems to be incapable of stabilizing emulsion droplets below its

critical overlap concentrations.

• Emulsion stability is obtained tOTboth hydrophobically-modified polymers at concentrations that are vastly in

excess of the critical overlap concentrations and that are postulated to be in the entanglement region.

We have made significant progress in our understanding of polymerization fronts. We have observed two

instabilities in propagating fronts of methacrylic acid polymerization, both of which give the appearance of a spin

mode. One occurs with liquid monomer when the tube is subjected to an external airflow to increase the rate of heat

loss. It is a novel instability caused by convection related to bubble formation. Spinning modes very similar to

ones observed in solid-state combustion reactions were observed when the initial methacrylic acid/initiator solution

was mamtained at 0 °C. The helical pattern left in the polymer and temperature profile measurements confirm for

the lhst time the presence of a true spin mode in a constant velocity polymerization front. Using an IR camera, we

were directly able to observe the spinning heads. Questions remam about the other spinning modes and the role of

surtace tension induced convection, which may be an excellent candidate for KC-135 flights.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 3

TASK INITIATION: 4/93 EXPIRATION: 4/95

PROJECT IDENTIFICATION: 962-26-08-10

NASA CONTRACT NO.: NAG8-973

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Lochhead, R.Y., and Rulison, C.J. An investigation of the mechanisms by which hydrophobically modified hydophilic

polymers act as primary emulsifiers for oil-in-water emulsions l.poly(acrylic acids) and hydroxyethylcelluloses. Colloids

and Surfaces, vol. 3, no.2, 2818 (1994).

Nagy, I.P., Keresztessy, A., Pojman, J.A., Bazsa, G.. and Noszticzius, Z. Chemical waves in the iodide-nitric acid system.

J. Phys. Chem., vol. 94. 6030-6037 (1994).

Volpert, Vit. A., Volpert V1. A., and Pojman, J.A. Effect of thermal expansion on stability of reaction front propagation.

Chem. Eng. Sci., vol. 14, 2385-2388 (1994).

Presentations

Basu, K., and Mathias, L.J. "Bis-functionalized polymers and cyclopolymers form ct-hydroxymethylacrylates with

pendent non-linear optical/liquid crystalline moieties." Southereastern Graduate Polymer Conference, April 13-15, 1994.

Khan, A., and Pojman, J.A. "Hydrodynamic instabilities in propagating fronts of polymerization." Gordon Research

Conference on Oscillations and Dynamic Instabilities, Newport, RI, August 11, 1994.

Khan, A., and Pojman, J.A. "Convective instabilities in propagating fronts of addition polymerization." Department of

Chemistry and Biochemistry, University of Southern Mississippi, Mississippi Academy of Sciences, Biloxi, MS,

February 17-18, 1994.

Lochhead, R.Y., and Rulison, C.J. "The adsorption of hydrophobically modified hydrophilic polymers to oil/water

interfaces." American Chemical Society National Meeting, Washington, DC, August, 1994.

Lochhead, R.Y., and Rulison, C.J. "Adsorption of hydrophobically modified water soluble acrylic acid and cellulose based

polymers at dynamic oil/water interfaces." 68th Americal Chemical Society Colloid and Surface Science Symposium,

Stanford, CA, June. 1994.

i i i i iaoi i i oi i i i i l i i oi i i i i i i i i i i i i i i i i i i i i i i i i i i i ooI I I I II I I I I oIII oI II i i i I i oi i i i i i i oi i ooI I I I uII I I I I I I I I IO I Ill IoI oIO I ooI Ill Ill I I I I I oI III I I UIII I I I I I I I I I uI I OI II I I I I I I I I oI IOI I II oI I I I oI I I I I I I I I I OI I lI I I I i I I I I I I oI oI IaI I I I I ! I I aI IaI I I III I I I I I IIt I I I I I I I I oI

11-569
II. MSAD Program Tasks-- Ground-based Research Discipline: Materials Science

Lochhead. R.Y.. and Rulison. C.J. "The kinetics of polymer diffusion to liquid/liquid interfaces by drop w)lume

techniques." Society of Cosmetic Chemists National Meeting, Las Vegas, NV, May, 1994.

Lochhead. R.Y.. and Rulison, C.J. "An investigation of the ability of poly(acrylic acid) microgels to stabilize

oil-in-water emulsion systems under shear flow conditions." Society of Cosmetic Chemists National Meeting, Las Vegas,

NV, May, 1994.

Lochhead. R.Y., and Rulison, C.J. "A study of the adsorption of hydrophobically modified poly(acrylic acids) from

aqueous solution onto hydrophobic/hydrophilic interfaces by densionetry and ultraviolet techniques." Society of

Cosmetic Chemists National Meeting, Las Vegas, NV. May, 1994.

Lochhead, R.Y., and Rulison, C.J. "The kinetics of polymer diffusion to liquid/liquid interfaces by drop volume

techniques." Southeastern Graduate Student Conference. Hattiesburg. MS. April, 1994.

Mathias, L.J. "Polymerizations in microgravity." NASA Microgravity Materials Science Conference, Huntsville, AL,

May 24-25, 1994.

Mathias, L.J. "Cyclopolymerizations of ethers and ether dimers of RHMA." University of Alabama, Tuscaloosa, AL, June

19, 1994.

Mathias, L.J. "Convection instabilities in propagation fronts of addition polymerization." American Society of

Mechanical Engineers, 14th Annual Winter Conference. New Orleans, LA. December 1, 1993.

Mathias, L.J. "Propagating fronts of polymerization." International Workshop on Dynamism and Regulation in

Non-linear Chemical Systems, Tsukuba, Japan, March 23, 1994.

Mathias, L.J. "Factors affecting propagating fronts of polymerization." MacroAkron IUPAC International Symposium

on Macromolecules, Akron, Ohio, July 11, 1994.

Pojman, J. "Instabilities in propagating fronts of polymerization." Gordon Research Conference on Oscillations and

Dynamic Instabilities, Newport, RI, August 1l, 1994.

Pojman, J.A. "Traveling fronts of addition polymerization." Symposium on Pattern Formation in Polymers: From

Equilibrium to Nonequilibrium, Tokyo, Japan, December 6-7. 1993.

o o el lea I Jlallo III Ill ii Jl Ill Ill elll Ill ill iii ill iiiolll Ill lo I Ill I ii Itl iii oil I i iOil ill Oil la i iii ii IiI I o I III i iii IJlllll lie Ill ill III llllll Ill I Ill III III l III Ill III mII iii IiI Ill Ill II III II I la I la I I I I I el I I I I la I el I la I o I II ii Ill I el I ii III I II OII mJl I OI I e IIII II a I I

I1-570
Quantitative Analysis of Crystal De&cts by Triple Crystal X-Ray DifFraction

PRINCIPALINVESTIGATOR:Dr. Richard J. Matyi University of Wisconsin, Madison

CO-INVESTIGATORS:

D. Gillies NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The objective of this task involves the development of various x-ray diffraction methods for the analysis of

semcionductor materials, particularly ZnSe and its ternary alloys. The specific goals are (1) the development of

high resolution triple crystal x-ray diffraction methods for the quantitative analysis of structural detects in

semiconductor crystals; (2) the application of these analytical methods to compound semiconductor crystals (grown

both in ground based experiments, and eventually, in microgravity) to achieve a better understanding of the effects

of the crystal growth environment on the generation of defects; and (3) the transfer of this analysis technology to

the Space Science Laboratory. at the Marshall Space Flight Center (MSFC).

TASK DESCRIPTION:

The overall investigative approach of the research is the coupling of a new materials characterization tool (triple

crystal x-ray diffraction) to the development of a new crystal growth system (ZnSe and its ternary alloys grown in

microgravity). ZnSe and various alloy samples are being supplied by MSFC and are currently being analyzed by

triple crystal diffraction methods to articulate the mosaic structure and the density of statistically distributed

dislocations. Diffuse scattering is being used to monitor the surface preparation. Plans are being made to

investigate the use of anomalous transmission as an alternate means of characterizing the defect structure, and to

measure the volume fraction of twinned material using x-ray methods. The information obtained in these analyses

is being forwarded to MSFC for corroboration by other analytical methods.

TASK SIGNIFICANCE:

The Microgravity Science and Applications Division at the Marshall Space Flight Center is engaged in a program

under an approved flight experiment for the growth of the important semiconductor ZnSe and its alloys in space.

Of prime importance in any crystal growth process is the reduction of the density of grown-m structural defects and

the understanding of the relation between crystal growth and defect generation. Recent research at the University of

Wisconsin - Madison has demonstrated that an analytical technique known as mple-crystal x-ray diffraction is

capable of clearly differentiating the defect-tiee, "perfect crystal" regions of a sample from regions that are

structurally defective. In this research program, we will use triple-crystal x-ray diffraction and related methods to

examine the evolution of crystal growth detects as a function of crystal growth and relate the nature and quantity of

these defects to the growth process. This differentiation and measurement of the effect of defects will be used to

give a clearer insight into the effects of microgravity on the growth of technologically-important crystals.

PROGRESSDURING FY 1994:

Since this program began on July 1, 1994, we have been establishing the capabilities to perform the proposed

research. Instrumentation has been modified to permit the analysis of at-grown ZnSe crystals, and preliminary

analyses of samples have been performed. A graduate student hat been hired to perform the research. A kick-off

meeting has been scheduled for October 20, 1994 at MSFC to discuss preliminary, results and to establish an

analysis schedule.

i ii I I II I II I II II I ii i I I I ii l II l II l ii I l i I l I ii is l I II I I I II I I I II Ill I I I i i i II I II IIS I II I II I II I I I I I I I I I i i II I I I I I i i II I II I IS Ill Ill II s I II i i I i I i I s II I I II i i i IS iii. II I II I i ill i l i l III I I i i i is I l i i i, l iii i I I Ill, ill III I ii i ii I I I i i i i tl iii iii ii i iii i i i ii i iii iii l iii I I I I i l i i

II-571
If. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

; Ja o i a o | o a o 11 o o o o o Ia o ! o I | o i uo ! i! ooo a o lao I _ o o o o | i oo o o o; a o I I o |a i | io o ii o i a o n a o o o a o |a o oi a I b a o o o o o I a o i ai n ani o g o | a o I oo | o o o ao I a o o _ i o i o o o o o oo o o o o o I _ o I o o I ao | o o I a o I I o | I J o| i o I a o la | | a o o | a o Iu o u a ! | a o _ a o o i ao Ia | ! a o i a o I ! o I Io |! o a a o u a o u I oo I o o a o o a o ! a o aa o n a o I u _ | uo o

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 7/96

PROJECT IDENTIFICATION: 962-21-08-18

NASACONTRACT NO.: NCC8-052

RESPONSIBLECENTER: MSFC

IIIIIIIII III IllIllIni lllIll IIIIlUll IIlln iiinl IiiIIIIIIIIiiiIiiiIiiIIiiiiiiiiiIn IIiIlIIIIIIIiiIIIIii|IIIIiIIIIiI IIIIiiIIIIIIIIIiiiiiiiIiiIiiIIIIiiIIIIIiiIiiiiiiiIIiiiiiiiiiiII|iIiIIiIIiii|IiiiiiiiiiiiiiiiiiiiiiiIIIIIIIIIIIiiiiiiii¢ iiiiiiiii

11-572
The Interactive Dynamics qf Convection, Flow and Directional Solidification

PRINCIPALINVESTIGATOR:Prof. T. Maxworthy, Ph.D. University of Southern California

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

In order to assess and control the effects of residual spacecraft accelerations on the growth of high quality crystals,

full numerical simulations will be conducted. It is anticipated that this approach will lead not only to a

minimization of the adverse effects of the flow on the crystaJ growth process, but also to the development of

strategies for employing externally imposed flow fields to gain some degree of control over the solidification

dynamics. Questions of interest concern the selection of length scales, the persistence of traveling waves, and of

oscillatory instabilities in the nonlinear regime. Time dependent direct numerical simulations performed will allow

investigation of these mechanisms in isolation, as well as with their combined effects.

TASK DESCRIPTION:

1. Study the types of morphological instability that are to be found during the directional solidification of binary

mixtures;

2. Attempt the control of such instabilities using torced flow over the solidifying interface and assess the

usefulness of reduced gravity in modifying the process, thereby improving the quality and reducing the defect in

manufactured products.

TASK SIGNIFICANCE:

The basic mechanisms involved in controlling such nonlinear dynamical phenomena are of value to other fields of

science and engineering, and the space environment may provide a suitable test bed lor examining such ideas. This

could be beneficial to control the solidification process by employing externally imposed flow fields to improve the

quality and reduce defects in manufactured alloy products.

PROGRESSDURING FY 1994:

Since the award of this grant on June 16, 1994 we have concentrated our concerns on the design of the apparatus to

carry out this task. During this period a Leitz Interferometric Microscope was made available by the Materials

Research Section of NASA LeRC, and has been incorporated into the design. Some delays have resulted since the

microscope was not physically available to us until the end of August. It now appears that our original concept will

have to be modified to fit within the constraints imposed by the physical dimensions of the microscope. We

anticipate the design and manufacture of the test cell will be completed by the end of November.

We have been tortunate in securing independent, one year funding, for a student to work on this pmiect. He is a

Chinese National from Northwestern Technical University in Xian, who has had considerable experience in this area

of research. We anticipate significant progress once the apparatus is tLaally available for his use.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-25-05-26

MS Students: 0 RESPONSIBLECENTER: LERC

PhD Students: 1

ii-573
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

in. n. i. i i In i. i i tll..g i hen i I Il.l|l n l I II e lll|l n. I g. I! III I H I. I I n n I QH H il|lll6||el|.||lllJlll|llllgl|U0|gUl0|lNI J|H ||ll|||l|Ull mU||leDla|U|llJ|10||10WHII ll|l |lll|lIHl|l |.l|aIHH I JH I I_ll||l HI HH0|HHII HI III I. I I| III I I

Y2BaCuC)s Segregation in YBa2Cu_O_., During Melt Texturing

PRINCIPALINVESTIGATOR:Dr. Paul J. McGinn University of Notre Dame

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this ground based investigation is to understand the segregation of fine second phase Y_.BaCuO<

(211) precipitates during so-called "melt texture growth" of the superconductor YB_Cu_O, (123).

TASK DESCRIPTION:

In melt texturing of 123, one of the goals is to refine the 211 that is present in the textured microstructure as much

as possible to enhance flux pinning. However, segregation of free 211 will affect the ability of the 123 to pin

magnetic flux. It is unclear if segregation is an unavoidable consequence of precipitates being pushed by the

solidification growth front, and what role is played by gravitational effects. The goal of this project is to understand

the causes of 211 segregation. The effect of a number of factors on texturing will be examined to determine what is

causing the observed segregation.

Through a series of melt texture growth experiments the effect of Pt additions on 211 size, and more importantly

the 211 size dependence of segregation, will be determined. The effect of 123 growth morphology on 211

segregation will also be examined. This will allow for determination of whether the observed segregation is

specific to only one morphology of 123 growth, or is characteristic of all 123 growth. The growth mode will be

altered by using different techniques to achieve 211 refinement. It is anticipated that containerless processing

experiments will be included in this part of the study as they will provide the best opportunity to observe

impurity-tree growth. A series of experiments will also be performed in which the viscosity of the melt will be

altered to determine how the level of 211 segregation is affected.

After the effect of the above factors is understood experiments will be performed to attempt melt texturing of 123 in

a microgravity environment.

TASK SIGNIFICANCE:

It is expected that this research will identify important factors affecting the segregation of fine 211 particles during

the melt texturing of the 123-type high temperature superconductors. It will enhance the understanding of the

crystal growth process and the development of the microstructure. It is anticipated that knowledge gained from

working with this technologically important system will be applicable to other systems exhibiting similar crystal

growth features.

PROGRESSDURINGFY1994:

A process for routinely growing Nd-123 seed crystals 2-3 _ on edge has been developed. These crystals are being

used to seed the growth of Y-123 single crystals. Quenching from high temperature is being used to isolate

growing Y-123 crystals. A mild etch process (acetic acid based) has been developed for extracting the crystals with

only modest crystal degradation. Crystals are now being characterized as to the extent of 211 segregation and its

relationship to the growth mechanism of the Y-123.

II I I I I I I I I II It I I I I I I I I I I I I I I II I I I I I I I I I I I II I I| I I I i I I I I I I I II I l I I I I I I I I II I I I I I I I I I I II I I I I I I I I I I I II I I Ill I I I I I II I I I I l I II I II I III I I I I I I I lU | I I I II I III I I I I I II III I I l II I I I I I I I I I I I II I I I I I I I I I I II I II I I I l I I i II l I I I I I l I I I I II I I I I I I | I I l II I I I I I l I I l I I Il I l I I l I I I I I I

11-574
I[. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

,lllll,tl, j_tIie_0_lo_l_0_i_00"_.0_a_6i_i_0i_0._a_i|0i_i_Ii_1ii_.0_.0t_ijI_"_0H_i.0t_i_g_|_tH_i_ii0i_i_¢|_i_I_|_o_|i_j_._|_i_i_i_0_10B_I_o_00t.0_0.i_.1_0_l_i

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 1

MS Students: 0

PhD Students: 1

TASK INITIATION: 6/94 EXPIRATION: 6/95

PROJECT IDENTIFICATION: 962-21-08-29

NASA CONTRACT NO.:NAGS-1064

RESPONSIBLECENTER: MSFC

I I I I I I II I o I o I I I i i i II o i i e III I ii II I II I I I e II I I II I I I I I I i I I I I I I I i i i Ia i I I I I i e i i i II i o I I el i I I I I Ii ii i i I I i i a i II o I I i i i i i i i i iI I I I I I I II I I II I a i i i i i I I I I I II I I I i ii i i i i i i II I Io I I I i i I i iii i I i i ii a ii i i i i I I I I I I o I I ii i iI I I I I i i o i i i i ii iI o I I I I I I I oI I I I II II I I ii III I I a I I o I I I II

11-57 5
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

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Interaction of Hele-Shaw Flows

Nonlinear Dynamical Interplay

with Directional Solidification:

and Control Strategies

N u merical lnvestixation of"the

PRINCIPAL INVESTIGATOR: Prof. Eckart H. Meiburg, Ph.D. University of Southern C_flirornia

CO-INVESTIGATORS:

T. Maxworthy University of Southern Califl_rnia

TASK OBJECTIVE:

In order m assess tuld control the effects of residwal spacecraft accelerations on the growth of high quality cryst:ds,

full numerical simulations will be conducted. It is anticipated that this approach will lead not only to a

minimization of the adverse effects of the flow on the crystal growth process, but 'also to the development of

strategies for employing externally imposed flow fields to gain some degree of control over the solidification

dynamics. Questions of interest concern the selection of length scales, the persistence of traveling waves, and of

oscillatory instabilities in the nonlinear regime. Time dependent direct numerical simulations perR)rmed will allow

investigation of these mechanisms in isolation, as well as with their combined effects.

TASK DESCRIPTION:

1. Study the types of morphological instability that are to be found during the directional solidification ¢)f binary

mixtures;

2. Attempt the control of such instabilities using forced flow over the solidifying interface and assess the

usefulness of reduced gravity in modifying the process, thereby improving the quality and reducing the defed in

manulactured pr_Mucts.

TASK SIGNIFICANCE:

The basic mechanisms involved in controlling such nonlinear dynamical phenomena are of value to other fields of

science and engineering, and the space environment may provide a suitable lest bed for examining such ideas. This

could be beneficial to control the solidification process by employing exterually imlx)sed Ilow fields to improve the

quality and reduce defects in manufactnred alloy products.

PROGRESSDURING FY 1994:

Since the initiation of the grant on 6/16/94, design plans have begun for the apparatus to carry out the proposed

tasks. We anticipate that the equipment will be in operation by February 1995. Efforts have been focused o[1 the

development and implementation of a highly accurate computational approach. Since the computational domain has

a curved boundary at the solidification front, we employ a conlonnal mapping approach to obtain a recttmgular

domain. By assuming periodicity in the spanwise direction, the mapping can be performed analytically, which has

the advantage of providing the analytical relationships between the original and the transformed wmables. We have

derived the relevant equations, boundary conditions and transformation terms in the computational domain. Since

the problem is nonperiodic in the direction of solidification, we employ a compact finite difference method in that

direction, while a spectral representation has been chosen for the spanwise direction. For the case without flow, we

have numerically computed the growth rates of small wavy perturbations to the interlace, and made preliminary

comparisons with the classical linear stability theory of Mullins and Sekerka. The comparisons indicate excellent

agreement.

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II-576
STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 6/94 EXPIRATION: 6/96

BS Students: 0 PROJECT IDENTIFICATION: 962-25-05-27

MS Students: 0 NASA CONTRACT NO.:NAG3-1619

PhD Students: 1 RESPONSIBLECENTER: LeRC

I I I ¢ OI I l Il I I OI I I I OI l I I OII I II OI I l I I Oe II II I I I I I I I I I I I II I I I I a I OI I I I II I I I I I I I OI Il I I OI I I I I I I I I II I I I I l I I l I I I I OII s I I I I I OI a I i i I I io ii I I o I o I I I I e I II OI a a i I I I I a I I a I I II Ie I I I a i I I o o a Io I I 1111111111111 o I II II i i i i i a i o I a i I II Ia i i I I i i I o I I I II I ii i i i i i i i o I i Ii i i i i I i i i i i i

11-577
The Synergistic Effect of Ceramic Materials Synthesis Using Vapor-Enhanced Reactive Sintering

Under Microgravity Conditions

PRINCIPALINVESTIGATOR: Prof. John J. Moore Colorado School of Mines

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The prtmary objective of this research is to develop a technique tbr processing advanced ceramics in the form of fine

powders, whiskers or platelets. The secondary objective is to determine the extent of vapor phase reactions,

including convection, in combination with gravity driven flow, on the process. Important concerns include product

particle size and purity. Products should have particle sizes allowing tor efficient handling and subsequent

processing and/or function. Control of the chemical reactions and particle sized is necessary for the achievement of

this objective.

TASK DESCRIPTION:

Titanium diboride is synthesized according to the reaction Ti+2B=TiB_. and titanium diboride + alumina (hl:O3)

composites are synthesized by the reaction 3TiO2+3B203+10Al=3TiB_.+5AI203. The first reaction was chosen for

its relatively simple solid-solid reaction, allowing the fundamentals of the reaction to be accurately evaluated. The

TiB2 is formed via a combustion synthesis reaction in the propagating mode, which has high product purity and

rapid reac;ion rates as inherent advantages of this process. The second reaction also uses the propagating mode, but

is complicated by the fact that the reacting components become both molten and gaseous during the ignition

process. Convection, therefore, plays a much greater role than in the ftrst reaction. Both reactions will be carried

out in both inert, i.e., Ar gas, and reactive, i.e., HCI gas, environments in order to evaluate the effects of vapor

transport on the combustion synthesis reaction. A complete examination of the process variables, including micro

and increased gravity, will be completed to examine the effect on the reaction.

TASK SIGNIFICANCE;

Fine powders may be used as raw materials for subsequent processing techniques, while platelets and whiskers may

be used as reinforcement materials in composite structures. Evaluation of reactions in microgravity enhance basic

underst_mding of ground-based reaction mechanisms.

PROGRESSDURINGFY 1994:

Effects of gas pressure on the combustion synthesis of TiB2 in both argon and HCI have been investigated. In both

cases as the pressure increases the ignition temperature increases and the combustion temperature decreases. It is

also noted that as the combustion temperature increases the grain size of the product increases. Experiments in

microgravity have been completed, and all reactions show a large increase in combustion temperature over

ground-based results, as well as a more uniform grain size. Microgravity environments decrease the effect of

convection, but the reaction mechanisms that depend on convection have yet to be fully clarified.

The alumina-titanium diboride system has also been investigated using reactive and inert gas pressure and

microgravity. In this system, a vapor-liquid-solid reaction occurs at the reaction front, producing different results.

Under normal conditions, gas pressure increases, ignition temperature decreases, and the combustion temperature

increases, producing varied microstructures. In addition the reactive gas seems to have little effect on the

combustion temperature. Though not yet fully analyzed, microgravity results in large increases in combustion

temperature. However, microstructures still show large variations even within a given sample.

ii I I i lll ii i i i i I i, I i a i o i i. i ii I I I I i il iI i i I e I i i I o I I Ii i ii I Ii I ltll I II ] ii i i, I I i i t i ii I I i i I I I I a J II I II II l I 1Otilll I I I Ill I J II I el I II I II e I i is i i i i Ill o J el oil i I el o o o II I iii Ill I III lie 1el I Ol Ill I l a I Ill 1011111011 IS I lea I II lie Ill III Ill III 111 III Ill eli 011 Olie Ill r l I II I i

11-578
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

i_ o i o i i* i n o i i * i i o i i *o i o *no * i i o i | * I Jo ! i i o I | o i i o o i o o io * ia | n a o o i a I I * o i I of n o o I a o I n * I I o n a o* i o *u* o a o | a o| a o o I o | I * I I* Io * I n * I | * I n* In o I I * I I o o I o o I I I !I * o I o I I I o | I n * n I o o Io * iall I o I I * o I * * II | | * I o I u * o * * * I I * I I * o oI o IIII I o * I I o n a * * _ n o _ ni I n a n a o n * * o I on I o o I o o n o o o I _o _ _

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/93 EXPIRATION: 12/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-26-05-10

MS Students: 0 MS Degrees: 1 NASA CONTRACTNO.: NCC-289

PhD Students: 3 PhD Degrees: 0 RESPONSIBLE CENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Lantz, C., Moore, J.J., Readey, D.W.,

Indianapolis, IN, 1994.

"Combustion synthesis of TiB2 powders." ACerS 96th Annual Meeting,

Lantz, C., Moore. J.J., Readey. D.W., "Combustion synthesis of TiB2 powders." AIChE National Meeting, Denver, CO,

1994.

Tefft, P., Moore, J.J., Readey, D.W.. "Formation of AI203-TiB2 composites with a high temperature synthesis

reaction." ACerS 96th Annual Meeting, Indianapolis. IN. 1994.

Tefft, P., Moore. J.J.. Readey. D.W.. "Formation of A1203 and TiB2 powder mixtures by high temperature synthesis."

AIChE National Meeting, Denver. CO, 1994.

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II-579
[I. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

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Diffusion, Viscosity, and Crystal Growth in Microgravity

PRINCIPALINVESTIGATOR: Prof. Allan S. Myerson Polytechnic University, New York

CO-INVESTIGATORS:

A. lzmailov Polytechnic University, New York

TaSK OBJECTIVE:

The results of this research should improve the operation and data analysis of existing microgravity crystal growth

experiments and aid in the design of new hardware/br such experiments.

TASK DESCRIPTION:

Components of this research include:

• Experimental studies of the diffusion coefficients and viscosity of triglycine sulfate (TGS), KDP, and other

compounds of interest to microgravity crystal growth in supersaturated solutions as a function of solution

concentrations, solution age, and solution history;

• Development of a theoretical model of diffusion and viscosity in the metastable state;

• Development of a model of crystal growth from solution including nonlinear time-dependent diffusion and

viscosity effects;

• Employment of the model with and without buoyancy-driven convective flows to predict results of Earth and

microgravity crystal growth experiments and to compare these results with experimental results; and

• Development of a computer simulation of the crystal growth process that will allow simulation of microgravity

crystal growth, including the effects mentioned above.

Plans are to develop the adequate physical description of the crystal growth process in the supersaturated solutions.

To achieve this goal, it will be necessary to take into account the nontrivial dependencies of such transport

coefficients as diffusivity and viscosity on the solute concentration and solution temperature and age. The research

program's approach will include obtaining the characteristic time lbr the crystal growth process in the supersaturated

solutions, i.e., to obtain the duration of the metastable state relaxation that leads the system "crystal +

supersaturated solution" to the equilibrium state. This equilibrium is the equilibrium between the crystal surface

and the entire remaining volume of the surrounding saturated solution.

Another facet of the program will theoretically determine from the proposed model the difference in the

concentration, temperature, and convective flow fields between an Ea_-grown crystal and one grown in

microgravity. This will also allow a comparison of the gains in face size and stability that might accompany

microgravity crystal growth.

Comparison of theoretical predictions to the real experimental data will verify the theoretical model and determine

numerical values tbr model parameters that have not been measured.

TASK SIGNIFICANCE:

Since crystallization from solution occurs in supersaturated solutions, the properties of these solutions and their

role in nucleation and crystal growth are of interest. Recognition of this has led to a number of studies of

supersaturated solutions and their properties.

i i i ii l I I ii i l i I I i i l I II l ii I Iil I I I I ii iII I I I I I i i i i liI I I I I i i I I l i ii I ii i i i l i i ii ii n i I i i iii l I el i el II i I ii II I II I II i l lie ill II oII ill l Ill ill I IS I II I el I II I I I II I I Ill I II III I II I II Ill I II IIII Ill Ill III Ill Ill III I lllll Ill Ill l lll I llilllll III II l II Ill II I I II III II III II l I I

I1-580
PROGRESSDURING FY 1994:

Diffusion coefficients and viscosities of KDP, ADP and TGS have been measured over their entire undersaturated

concentration range and in the supersaturated region.

An electrodynamic levitation technique was used to measure the water activity in KDP, ADP and TGS. This 'allows

calculation of activity and activity coefficient for these materials in highly supersaturated solutions and allows

estimation of the spinodal curve.

The diffusion boundary layer equations related to crystal growth from solutions are derived for the natural convection

case with viscosity and density dependent on solute concentration. Solution of these equations has demonstrated

that at the vicinity of the saturation concentration there is the following non-trivial dependence of the solution

viscosity h on its density r: h = h (r) a r _/_. This theoretically obtained result has been verified by our expertmental

"data.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 3/93 EXPIRATION: 3/96

BS Students: 0 BS Degrees: 0 PROJECT IDENTIFICATION: 962-26-08-09

MS Students: 0 MS Degrees: 0 NASA CONTRACT No.: NAGS-960

PhD Students: 1 PhD Degrees: 1 RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Myerson, A.S. "Diffusion, viscosity, and crystal growth in microgravity." NASA Microgravity Materials Science

Conference, Huntsville, AL, May 24-25, 1994.

Myerson. A.S. "New results for crystal growth from solution." Fifth Eastern Regional Conference on Crystal Growth,

Atlantic City, NJ, October, 1994.

11-581
An Electrochemical Method to Measure Diffusivity in Liquid Metals

PRINCIPALINVESTIGATOR: Prof. Ranga Narayanan University of Florida

CO-INVESTIGATORS:

T. Anderson

A. Fripp

University of Florida

NASA Langley Research Center (LaRC)

TASK OBJECTIVE:

A research program will be conducted, that uses coulometric titration to measure oxygen diffusivity in liquid

metals. Important aspects of the program are to estimat_ the effect of low gravity on the diffusivity measurements

and to design experiments where the use of a low gravity environment significantly reduces the adverse effects of

convection in the melt. The availability of these "benchmark' values of diffusivity will be useful for assessing the

reliability of different experimental designs and operational procedures for measuring diffusivity on earth.

Another science objective of this study is to establish a clearer picture of the constitutive behavior of "Fickian

diffusion' of oxygen in liquid metals. In particular, we will accurately measure the temperature dependence of the

oxygen diffusion coefficient.

TASK DESCRIPTION:

In this study an existing experimental 'cell' that has been modified by these investigators is used. An example of a

system that is studied is the diffusion of oxygen in tin. The experimental arrangement consists of 2 electrochemical

cells sharing a common working electrode, viz: tin. A representation of the cell is given by:

Cu,CuO II YSZ II O in Sn II YSZ II Cu,CuO

Here yttria stabilized zirconia (YSZ) is the solid state electrolyte through which oxygen ions are transported into or

out of the liquid tin. In these experiments, one cell is used to establish a known boundary condition, usually a

negligibly small concentration, while the second cell is operated in an open circuit mode to measure the

concentration at the opposite boundary. The solid state electrolytes and tin are physically arranged so that the

gravity vector is collinear with the gradient of concentration.

One of the YSZ plates is at the top and has a small overflow port to accommodate the expansion of tin, upon

heating. Care is taken to avoid leakage of oxygen/tom this or other sources. Temperature gradients, in this so

called isothermal experiment, are reduced in order to avoid natural convection under earth's gravity. Under earth's

gravity, it is also important to ensure that oxygen concentration gradients are parallel to the gravity vector so that

the melt is not 'top heavy'. This means that the oxygen concentration should be low at the 'bottom' of a vertically

oriented cell. This in turn implies, that oxygen depletion takes place from the bottom or oxygen addition takes

place from the top.

TASK SIGNIFICANCE:

The availability of a method that gives benchmark values of diffusivity in liquid metals has many uses. These

include the assessing of the reliability of different experimental designs and operational procedures tbr measuring

diffusivities under Earth's gravity, as well as defining the constitutive relationships in liquid metals. This latter use

is of fun "damental importance in understanding the behavior of liquid metals and alloys.

i i i i i i i I I I II I I l I i I I I I I I I eI Il i ii I l i l i i l sl eii i II ai i l i; l i li i ii i i i l i ii i ii ii ei i oi i i i i i l l ii i i l i l i i i ii i i i ¢i i i i t i ii i i| Ii i | Iii | Ii i i i ii i l l i i l l l l l i i i i l i ii l l i l i t i i l i i i i i i ii ll i l i i i i i i l i i il i li i i i i ii ii i i i ei i i i i I ii i i i I I I i i i it i l i i i i i i I t i i ii ii ei i l i i i ii i ii i i i ei i i i ii i

11-582
PROGRESSDURIN6FY 1994:

The main result obtained thus far in the study may be summarized as follows:

The measured values of diffusivity depended on the cell size and expermaental configuration. Measurements taken in

configurations that gave rise to gravity driven convective flows 'also gave larger values of diffusion coefficients than

measurements taken in configurations where the convective flows were apparently weaker. A detailed numerical

model with a sophisticated 3-D code was developed, which predicts the eflects of imperfections such as flits and

radial heat losses. Based on this modeling, it is concluded that even slight imperfections affect the diffusivity

measurement_ for all of the cell configurations studied. Other observations that were influenced by the cell

configurations were made. For example taller ceils, which were associated with large tune constants, increased the

measurement error because of mass transfer through an oveillow port. This port was included in the design in order

to accommodate the expansion of tin upon heating. Thus, the initial oxygen concentration and cell dimensions

both influenced the hydrostatic stability of the tin sample during a transient diffusion experiment. This is not

surprising as the transport process is essentially the transient version of the Rayleigh-B6nard problem and the aspect

ratio and Rayleigh number are two parameters which are found to define the stability criterion m that problem.

In brief, we believe that gravity driven convection inthe melt prevents accurate measurement of the mass

diffusivity of oxygen in metal systems by coulometric titration and thus likely in other measurement systems.

This situation represents a clear example where a reduced gravity environment is necessary to obtain meaningful

values of this important physical property.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 2/93 EXPIRATION: 2/96

BS Students: 2 BS Degrees: 2 PROJECT IDENTIFICATION: 962-25-08-26

MS Students: 1 MS Degrees: 1 NASA CONTRACTNo.: NCCS-20

PhD Students: 1 PhD Degrees: 0 RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Narayanan, R., Anderson, T.J.. and Fripp, A.L. "An electrocehmical method to measure diffusivity in liquid metals."

NASA Micrograity Materials Science Conference. Huntsville. AL, May 24-25. 1994.
Crystal Growth and Segregation Using the Submerged Heater Method

PRINCIPAL INVESTIGATOR: Prof. A. G. Ostrogorsky Rensselaer Polytechnic Institute

CO-INVESTIGATORS:

G. Mtiller

E. Monberg

Universitat Erlanger-Niirnberg

AT&T Bell Labs

TASK OBJECTIVE:

Fundamental studies of solute segregation at low levels of melt convection will be conducted using a programmable

multi-zone furnace modified for growth by the Submerged Heater Method. The specific objectives of these studies

are to:

1. Evaluate the suitability of the multi-zone furnace with the submerged heater to serve as a ground-based

solidification facility, useful for pre-and post-flight studies.

2.Seek explanations for previous space experiments not demonstrating the diffusion controlled segregation.

3. Determine the criteria that will allow the diffusion-controlled segregation.

4. Evaluate the benefits of using the SHM within a PMZF/'or future space experiments.

TASK DESCRIPTION:

The research plan is to use the Submerged Heater Method in ground-based experiments for studies of mass transport

in the melt at low Ra numbers. The effect of the equilibrium coefficient k will be particularly investigated. The

studies will focus on electronics materials previously studied in space (e.g., Ge, InSb) doped with elements having

different equilibrium distribution coefficients, ranging from k-0.5, to k~10-3. Directional Solidification and zone

melting procedures will be used during growth. The studies will be conducted using a programmable multi-zone

Mellen furnace modified for the SHM. The ground-based experimental and theoretical work will be accompanied by

numerical simulations. Numerical simulations will be used to model the transfer processes in the melt and to

optimize the growth conditions. Future space expertments designed for the SHM will also be modeled.

TASK SIGNIFICANCE:

We hope to demonstrate that the multi-zone furnace with the submerged heater is useful t`or pre- and post-flight

studies. The pre-flight studies may help to optimize the future space experiments. Our current "post-flight studies"

locus on solvent-solute systems previously used in space (doped Ge, InSb and GaSb). We hope to explain why

some space experiments did not result in diffusion controlled segregation.

PROGRESSDURING FY 1994:

Numerous modifications were made on the programmable lS-zone Mellen furnace. The furnace was calibrated and

eight growth experiment with Ga-doped germanium were conducted. Convex solid-liquid interface and exceptionally

unit`orm radial dopant distribution was obtained. We derived a nondimensional paramete, named the Segregation

number that can be used to estimate the influence of convection on segregation. An axisymmetric model of heat

and species transfer which allows studies of segregation in vertical Bridgman configuration (with and without the

submerged heater) was developed.

A transparent two-zone Bridgman furnace was designed and built. The experiments in the transparent furnace are

helping us to visualize melt convection and the shape and the position of the growth interface.

11-584
STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 1

TASKINITIATION: 4/93 EXPIRATION: 4/96

PROJECTIDENTIFICATION:962-21-08-15

NASA CONTRACTNO.: NAG8-952

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Ostrogorsky, A.G.. and Mtiller. G.

vol. 137, 64-71 (1994).

Normal and zone solidification using the submerged heater method. J. Cryst, Growth.

Proceedings

Ostrogorsky, A.G. "Grystal growth and segregation using the submerged heater method." Proceedings of the NASA

Microgravity Materials Science Conference, Huntsville, AL (1994).

Ostrogorsky, A.G.. and Dagojlovic. Z. "Heat and mass transfer in solidification by the submerged heater method."

Proceedings of the ASME Winter Annual Meeting. Chicago, IL 11994).

Ostrogorsky. A.G.. and Dagojlovic. Z. "Model of convection and segregation during growth by the submerged baffle

method." Proceedings of the International Aerospace Congress, Moscow, Russia 11994).

Books

MOiler. G., and Ostrogorsky, A.G. "Convection in Melt Growth" chapter in "Handbook of Crystal Growth."

North-Holland/Elsevier. vol. 2, pp 709-820, 1994.

Presentations

Ostrogorsky, A.G. "Control of heat and solute transfer in vertical Bridgman configuration." National Conference of

Israeli Association for Crystal Growth, November, 1994.

Ostrogorsky. A.G. "Directional solidification and zone melting using the submerged heater method." General Electric

R&D Seminar, March 29, 1994.

Ostrogorsky, A.G.. and Dagojlovic, Z. "Vertical Bridgman growth with and without a submerged baffle." 13th Conference

on Crystal Growth, AACG/West. June. 1994.

Ostrogorsky, A.G.. and Dagojlovic, Z. "Numerical simulation of heat and mass transfer in solidification by the submerged

heater method." Gordon Research Conference on Crystal Growth. Proctor Academy, NH. June. 1994.
II. MSAD Program Tasks m Ground-based Research Discipline: Materials Science

* ! i i I I * o ! o |I I * I ! * D* a e n n | | I o | I Iela o IIo I I o ! I aii ! | IIJ I I | | I * * ! I | | I o | | * i i n * I * * III I ! Io I| i | I * 6 ! o i * | DI oI I o i I * | * | | I I| I! * I! o | I | n I | ! I | | * i | I I * I I * * * * o i| * II | I I o o I | * I ! o I| I ii * I Ill i o | I | !I | I * I ! I I o I | * I! I Ig I I | o I I o I* ! I* o I ! * I I * I I* I I| | I* I Io I I * I *I |ta * ! 111 ! ! ,11111 * I* * I

Investigation of "Contactless" Crystal Growth by Physical Vapor Transport

PRINCIPAL INVESTIGATOR'.Dr. Witold Palosz National Research Council (NRC)

CO-INVESTIGATORS:

Y. G. Sha

D. Gillies

C.H. Su

S. Lowry

Universities Space Research Association (USRA)

NASA Marshall Space Flight Center (MSFC)

NASA Marshall Space Flight Center (MSFC)

CFD Research, Inc.

TASK OBJECTIVE:

The primary objective of this study is to evaluate the conditions required for growth of crystals without contact with

the side walls by physical vapor transport (PVT) in closed ampoules. The potentials and limitations of this

technique ("contactless" PVT - cPVT) with respect to crystal size, growth rate, crystal quality, and the potential

benefits of the microgravity environment tot this technique will be assessed. The conditions for growth of Pb(Se,

Te) by PVT will be determined. The evaluation of capabilities and limitations of the exiting facilities and

recommendations/'or space crystal growth facilities with respect to this PVT technique will be made.

TASK DESCRIPTION:

l. Development of numerical model of heat and mass transport in the growth system.

2. Development of termochemical model of transport of Pb(Se, Te) by PVT.

3. Fabrication and/or modification of exiting crystal growth furnaces.

4. Experimental investigation of transport of Pb(Se, Te)by PVT.

5. Performance of test crystal growth experiments.

TASK SIGNIFICANCE:

The benefits of the microgravity environment for crystal quality may be offset by strains and related crystal defects

caused by the interaction of the crystal with the walls of the growth container. The cPVT technique offers improved

growth conditions which may be beneficial for crystal growth both under ground and microgravity conditions. The

study will provide a comprehensive assessment of the technique as opposed to the limited scope of the literature

reports on the subject.

PROGRESSDURING FY 1994:

Budgeting arrangements are in process.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 2/95 EXPIRATION: 2/97

PROJECT IDENTIFICATION: 962-21-08-20

RESPONSIBLECENTER: MSFC

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11-586
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

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Containerless Processing for Controlled Solidification Microstructures

PRINCIPALINVESTIGATOR:Prof. John H. Perepezko University of Wisconsin, Madison

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

OBJECTIVE:

The mare research objective is the evaluation of the undercooling and resultant solidification microstructures in

contamerless processing, including drop-tube processing and levitation melting of selected alloys eksall experience

base tot microgravity experiments.

TASK DESCRIPTION:

The degree of liquid undercooling attmnable in a laboratory scale (3-m) drop-tube and levitation melting system can

be altered through the variation of processing parameters such as melt superheat, sample-size, and gas environment.

In a given sample, the competitive nucleation and growth kinetics between equilibrium and met&stable phases

controls microstructural development. The solidification behavior is evaluated through metallography, thermal

analysis, and X-ray diffraction examination in conjunction with calorimetric measurements of falling droplets and a

heat flow model of the processing conditions to judge the sample thermal history'.

TASK SIGNIFICANCE:

In the current program studies, solidification microstructures are being examined in selected Ni and Mn based

systems. The specific alloy selection is based on a metastable phase diagram analysis that allows lot the

identification of unique microstructures and microstructural transitions that may be produced by microgravity

containerless processing.

PROGRESSDURING FY1994:

A duplex partitionless solidification reaction involving fcc and bcc crystalline phases has been identified over a range

of compositions near that of the eutectic in the Ni-V system. The reaction can be thought of a._ the limiting case of

a eutectic transition (L--+ot+[3) in which ot and {3have the same composition as the liquid phase. Drop tube

experiments are being conducted to characterize the competitive formation kinetics of the fcc and bcc phases.

Near-equiatomic Ni-V alloys were solidified via contamerless processing methods and studied with electron

microscopy techniques. TEM has shown the presence of a duplex structure of fcc and bcc in large (- 10Omg) droplet

samples. TEM analysis has suggested that the duplex structure is not the result of a solid state transformation and

that the fcc and bcc phases have apparently nucleated independently from the liquid phase. A thermodynamic model

has been applied to the Ni-V system to calculate To temperatures for the relevant phases to map compositions and

temperatures for which the duplex partitionless reaction is possible. A kinetic model has also been foea, arded which

takes into account both the nucleation and growth rates of the competing fcc and bcc phases. The nucleation kinetics

analysis is in good agreement with experimental results. The model is currently undergoing further refinement to

include transient nucleation effects as well as the influence of heat flow on microstructural development. Additiomd

microstructural characterization will require cross-sectional TEM analysis of the containerlessly processed foil

samples

Near equiatomic Mn-AI alloys represent an important class of permanent magnet materials. The key Ierromagnetic

phase is a me.stable structure produced by solid state heat treatments. Recent drop tube and levitation melting

studies have demonstrated for the first tune that the metastable ferromagnetic z phase can be produced from the

liquid provided high undercooling is achieved. With specially prepared samples it has been possible to access the

thermodynamic driving forces involved in metastable "t phase solidification, it :dso has been determined 'I'o_'_

___D____j_i_i__t_'_1_*t_ti_i_t_*_o_i_l

11-587
temperature to help understand the metastable solidification reaction pathways which yield the metastable

ferromagnetic "_ phase during the containerless processing. The attainment of the liquid undercooling required to

nucleate the metastable phase from the melt is apparently facilitated by containerless processing. Additional

experiments of large droplets will examine in detail the competitive solidification kinetics involved in sample size

scale up in order to test and to extend the science base for a flight experiment. All expanded nucleation kinetics

analysis of the small droplet samples will explore the phase selection between the x phase and an additional

metastable product phase 7.

Building on the thermodynamic analysis a competitive nucleation model has been developed to account for the

observed phase selection. As part of a test of the kinetics model a detailed statistical study of the metastable product

yield as a function of sample size and processing gas, such as He and Ar gases, is underway. Furthermore, by

optimizing the containerless processing conditions in levitation melting processing it has been possible to obtain

essentially single phase samples of the x structure for scale up sample size (mm size) to approach bulk levels. In

the above studies a new calorimeu'ic system is being used to measure the temperature of falling drops during

containerless processing to assess the complete thermal history.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 1 MS De_ees: 1

PhD Students: 1 PhD Degrees: 1

TASK INITIATION: 12/91 EXPIRATION: 11/94

PROJECT IDENTIFICATION: 963-25-07-06

RESPONSIBLECENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Kim, Y.L and J. H. Perepezko. The formation of a metastable ferromagnetic phase during containerless melt processing

and rapid quenching in Mn-AI-C alloys. J. Appl. Phys, 71, 676 (1993).

Perepezko, J.H. Solidification reactions in undercooled alloys. Materials Science and Engineering, A179/180, 52 (1994).

Proceedings

Kim, Y.J. and J. H. Perepezko. "Formation of a metastable ferromagnetic phase during containerless melt processing and

rapid quenching in Mn-AI-C alloys." 31st Aerospace Sciences Meeting and Exhibit. American Institute of Aeronautics and

Astronautics, (1993).

Perepezko, J.H. "Kinetic competition in undercooled liquids." International Symposium on Metastable Mechanically

Alloyed and Nanocrystalline Materials, Grenoble France, June 1994.

Presentations

Allen, D.R., S. Das and J. H. Perepezko. "Kinetic competition during duplex partitionless crystallization." Wisconsin

Space Grant Consortium. Annual Symposium, August 1994.

Allen, D.R., S. Das and J. H. Perepezko "Kinetic competition during duplex partitionless crystallization." NASA Graduate

Symposium, Washington, DC, May 1994.

Perepezko, J.H. "Kinetic competition in undercooled liquids." International Symposium on Metastable Mechanically

Alloyed and Nanocrystailine Materials. Grenoble France, June t994.

Perepezko. J.H. "Containerless processing for controlled solidification microstructures." MSAD Review, Huntsville. AL,

May 1994.

IIlII IIIIIi IIII|IIIIIIII_IIIIIIIIIIIIIIIIIII_IIlIIIIIIIIIIIIIIIIIIII_IIIIII IIIIIIlIIIIIIIIII* I,IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIII_I IIeIIIIIIIII IIIIIiIIIIIIIIII IIIIIIIIIIIIII_IIIIIIIIlIIII IIIIIIIIIIII II*IIIIIIIIII_IIiiIIIIIIIII

II-588
Contaim'riess l'rocessin_,_ o! (7omposite Materials

PRINCIPALINVESTIGATOR:ProL John H. Perepelko University of Wisconsin, Madison

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The efteck_ of contamerless and low gravity processing are investigated in the synthesis of composite materials.

Existing models predicting criteria li)r incorporation of particles dispersed in a melt are applied to metallic systems

in a ,nicrogravity environment. The specific goals of the proposed research are to determine conditions necessary

lot an effective dispersion (i.e. uniform distribution of small particles), to characterize tile bonding characteristics of

particles with dm matrix when processed under micmgravity conditions; and to determine the implications of the

results for elfective solidification processing of composites. The ultimate goat of this work is to define conditions

necessary lbr effective c(mtainerless or low-gravity processing as well as Io determine characteristics which are

unique to microgravity processing. Specifically, tile results of this work will allow a critical test of existing

theoretic',d models dealing with melt-particle interaction as well as processmg conditions for particle incorporation.

The outcome ol these experiments will also further develop the basic understanding of relationships between

micr()suucture and properties of melal matrix c(}mposites dunng microgravity processing.

TASK DESCRIPTION:

The h)cus ol this study is on a model system of pure nickel with a discontinuous dispersion of reinlorcement

p;irlicles. The eflecls of gravity aud containment on the microstructural development in particle reinforced

colnposites iS studied using Ii-ee lall Io offset the linear acceleration of gravity. Given the extensive knowledge base

of lhe solidificalion behavior of nickel, assessment of melt and particle interaction becomes possible tllrough a

variety of means. The ev:duation of the microstructure obtained during containerless processing allows for

understanding of the conditions necessary a uniform distribution of particles without c(nnplications introduced by

containino vessels such as chemical contamination or particle/mold interaction. When containerless processing is

coupled with soli(lilicalion during li-ee lall, gravitatiowal effects such as tloatation, sedimentation, and density driven

convecliou c;tn be reduced. Variation of the magnelic field allows/or vigorous mixing of tile particles widun the

re(fitCh matrix, ;kSwell as solidificatioi_ with or without external contact. The degree of undercooling may be

c(mtn)lled by m()nil(_rmg lhe temperature with a two-color pyrometer and seeding crystallization with a needle when

the tleslletl temperature is reached. Through variation of the amount below the equilibrium freezing temperature a

specmlen is cooled, the driving force mid therefore rate of solidification can be directly influenced. The vaned

solidilicatJ(m lronl vehicity allows comparison to tx)th predictions made by theoretical models as well as

cxpcrimcnlal data obtathed without conmmerless or microgravity processing.

TASK SIGNIFICANCE:

Processing ol particle reinforced composites under microgravity conditions can re..sult in more uniform distributions

of panMes. With the reduction of the effects of gravity, problems inherent to conventional fabrication of metal

matrix composites such as lloatation, sedimentation, and density driven convection can be avoided. As h_s been

demonsuated m directional solidilication experiments, there is a critical rate at which solidification must occur for

hdl incorl)()ralion {i.e. engulfment) of panicles m occur. Particle engulfment into a forming solid in directional

solidilicalum experiments has been shown to depend on the temperature gradient, the solidification front velocity,

and the size of the particles for a fixed chemical composition. The limitation in these experiments has been the

conlamer, which changes the shape of tim front and which affects distribution of the particles through

particle/surface interaction. Solidification under microgravity conditions permits a study of particle distribution

without the el lecks of a container or gravity, which snpplements information obtained from prior directional

solidilication experimenLs. As with all ground based microgravity experlmenks, this work serves as a guideline of

steps to be followed in subsequmlt work actually conducted in space.

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II-589
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

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PROGRESSDURINGFY 1994:

The primary experimental lacilityl a ground based levitation system coupled with a laboratory scale drop tube, has

been constructed and tested. Composite samples ranging from lmm to 5ram diameter spheres are levitated, melted,

and "allowed to solidify during tree fall. Alternately, the system "also has the capability of melting and solidifying

the specimen on a substrate, which 'allows the thermal history of the droplet to be recorded using a two-color

pyrometer. Preliminary results indicate selection of nickel with aluminum oxide particles and nickel with titanium

carbide particles are combinations at two extremes of surface energy balance. Aluminum oxide particles are

typically excluded from the melt betore solidification while the titanium carbide is almost exclusively incorporated.

The cooling cycles which have been recorded are directly related to the resultant microstructures. Samples which

cool below the equilibrium freezing temperature have a greater driving force for solidification and thus freeze at a

higher rate than those which do not undercool. The changing rate of solidification is evident from the varied particle

density across the composite sample upon metailographic exanunation of interior sections. The particle distribution

as well as the cell morphology can indicate the comparitive velocities during solidification of the droplet. These

estimates of front velocity will be used to extend the experimental basis of support for existing models and possibly

make additional constraints to their use.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 1

MS Students: 1

PhD Students: 0

TASK INITIATION: 7/94 EXPIRATION: 7/96

PROJECT IDENTIFICATION: 962-25-08-31

NASA CONTRACT NO.:NAG8-1068

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Perepezko, J. H. "Containerless processing of composite materials." Wisconsin Space Grant Consortium Annual

Conference, Madison. WI, August 24-25, 1994.

Perepezko, J.L. "Containerless processing of particle reinforced composites." NASA Graduate Student Researchers

Program Annual Symposium, Washington, DC. May 11-13, 1994.

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I1-590
Comparison of the Structure and Segregation in Dendritic Alloys Solidified in Terrestrial and Low

Gravity Environments

PRINCIPALINVESTIGATOR:Prof. David R. Poirier University of Arizona

CO-INVESTIGATORS:

J.C. Heinrich University of Arizona

TASK OBJECTIVE:

A primary goal of this research is to identify the growth conditions for microgravity experiments delineating the

macrosegregation, microsegregation, and microstructure in comparison to the same features in directionally

solidified "alloys grown on earth with inevitable thermosolutal convection.

TASK DESCRIPTION:

Growth conditions are being defined by combining mathematical modeUing and simulation with terrestrial

experiments on binary metallic and model alloys. The investigation is carried forward at three universities, the

University of Arizona with D.R. Poirier and J.C. Heinrich, Cleveland State University with S.N. Tewari, and

Michigan Technological University with A. Hellawell.

TASK SIGNIFICANCE:

This research relates directly to ahnost all casting of metals as almost all practical cast metals are alloys which

solidify under conditions of directional heat transfer. Alloys develop microstructures of dendrite prtmary and

secondary arms, with micro-and macrosegregation patterns influenced not only by the basic physical processes of

solidification but also by convective currents. To separate out the convective effects, microgravity experiments are

necessary. Results of this work will eventually be included in numerical models lor casting of alloys and will

thereby impact alloys and will thereby impact a major portion of the economy.

PROGRESSDURINGFY 1994:

Hypoeutectic Pb-Sn _dloys, with compositions ranging from 10 to 58 wt. _ Sn, have been directionally solidified

at rates of 4 to 66 pan s t in measured thermal gradients of 67 to 110 K cm 4. As shown m Fig. 1, this resulLs in

macrosegregation along the length of the directionally solidified alloys. In the absence of thermosolutal convection,

the Un content "along the length would have been uniform, except for an initial length of the order of mushy

zone length.

Using the solutal build up between the traction solids corresponding to 0.2 and 0.6 as a measure of the

macrosegregation, it has been observed that the extent of macrosegregation increases with increasing tin content,

becomes maximum Ior 33.3 wt. _ Sn, and decreases with further increase in the tin content.

The intensity of the segregation along the length of the samples (and hence the presumed thermosolutal convection)

has been explained in terms of a parameter which includes the primary arm spacing, the volume traction

interdendritic eutectic, and the eutectic and tip compositions in the liquid. Alloy composition, thermal gradient and

solidification rate control primary, arm spacing, fraction eutectic, and liquid concentration at the dendrite tips.

To date numerical simulations have been done using the thermal conditions and composition of one of the

experimental ingots exhibiting 'Treckles" (also called "channel segregatesn). As early as 1000 s after the onset of

solidification, the numerical simulation shows upward flow next to the walls of the container, reminiscent of

plumes that emanate upward from a remelted channel within a mushy zone. At 2000 s in the simulation, the

channels along the walls are clearly evident and segregation is extensive, even though the leading part of the mushy

_1_o_I_I_j_t__B_o_i_I_l_B_I_o_o_I_I_I_o_o_j_o_l_e_Dq_D_e_D_o_I_I_1o_e_II_o_o_I_B_i_

11-591
zone has advanced only 1 cm. For example, the concentration of solute in the remelted channels is as much as

31.5% Sn and, of course, some of the Sn is transported from the mushy zone into the all-liquid zone by the upward

flowing plumes. With no convection, the simulation shows essentially no macrosegregation except for an initial

portion where solidification was effccted in a temperature field with a vanable gradient.

We now have many experimental DS castings that have been prepared in measured or known temperature fields. The

macrosegregation in each has been measured. In addition, microstructures have been taken from quenched ingots,

including regions near the leading part of the advancing mushy zone. With these microstructures, we have been able

to discern whether the solid solidified with a dendritic or cellular morphology. This is important because the extent

of macrosegregation increases with decreasing growth speed as the solid changes Iiom a dendritic to cellular

morphology.

During the last six months of the grant, we plan to define the growth conditions for a microgravity experiment that

could be clone in an existing NASA furnace for a space flight experiment. To assist in defining growth conditions,

we will run numerical simulations and study the effects of sample diameter, thermal gradient, solidification rate, and

"alloy composition. Hence, our next major emphasis will be on doing many more simulations based on the wealth

of empirical data gained thus far for verification. Alter this is accomplished, we will simulate directional

solidification of Pb-Sn alloys, under thermal scenarios that are achievable in a high gradient NASA furnace.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 2/93 EXPIRATION: 1/96

PROJECTIDENTIFICATION:963-25-05-09

NASA CONTRACT NO.:NAG3-1446

RESPONSIBLECENTER: LeRC

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11-592
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

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Kinetics of Phase Transformation in Glass Forming Systems

PRINCIPALINVESTIGATOR: Dr. Chandra S. Ray University of Missouri, Rolla

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objectives of this research are to: develop computer models for realistic simulations of nucleation and crystal

growth in glasses, which would also have the flexibility to accommodate the different variables related to sample

characteristics; and design and perform nucleation and crystallization experiments to verify these models. This

research will lead not only to improved methods for the analysis of kinetic parameters for nucleation and growth

determined from the peak profile studies of nonisothermal differential scanning calorimetry (DSC) or differential

thermal analysis (DTA) measurements of crystallization, but also to determination of the relative merits and

demerits of the theories presently used to study the phase transformations in glasses.

TASK DESCRIPTION:

This research is to study and explain the critical issues for the nucleation and crystallization in glass-forming

systems. The reported data tbr the kinetic parameters that determine the overall nucleation and crystallization

mechanisms are often difficult to interpret on the basis of existing theory. The interpretation becomes more difficult

when a variation in the characteristics of the glass, such as the thermal history, composition, particle size of the

sample, and concentration of the nucleating agent, are taken into account. This is probably due to the fact that the

theories that are presently used to analyze the isothermal and nonisothermal crystallization data for glass-forming

systems are over simplified. Glasses are traditionally prepared by cooling a melt and are not in a state of stable

equilibrium. Consequently, phenomena such as atomic mobility, cluster distribution, nucleation and crystal growth

rate, and viscosity pertaining to the nonequilibrium state need to be accounted for to establish an accurate

description of the phase transformations in glass forming systems.

Glasses (primarily silicate based) that devitrify polymorphically by homogeneous nucleation will be studied

experimentally and by computer modeling. A lithium-disilicate (Li_O.2SiO:) glass will be used for most

calculations and experimental measurements since the necessary thermodynamic and kinetic parameters are available

for this system. Other glasses that will also be investigated to verify the general applicability of the model include

soda-lime-silica (Na20.2CaO.3SiO2) and barium-disilicate (BaO.2SiO_). Crystallization experiments for the glasses

will be conducted by DTA or DSC using the conditions used for computer modeling, such Ks the quench rate used

to prepare the glass, sample weight, particle size of the sample, precrystaliization heat treatment temperature and

time, type and amount of nucleating agent, and DTA or DSC scanning rate. The experimental results will be

compared with those predicted by the model. If flight opportunities become available, glasses of identical

compositions will be prepared in space, and the same crystallization experiments as were conducted for the

Earth-melted control samples will also be performed/or the returned flight samples. The results from this research

are anticipated to yield a realistic model for nucleation and crystal growth processes occurring in glass-forming

melts which would provide not only an improved scientific understanding for these processes, but also allow a more

accurate quantitative analysis of the thermal analysis data. This would help to explain several anomalous

experimental results obtained for the kinetic parameters for crystallization and would lead to values that are more

physically interpretable. The relative role of heterogeneous and homogeneous nucleation on glass formation can be

determined, and the reported observation that a glass prepared in low gravity is more homogeneous and more

resistant to crystallization than an identical glass prepared at l-g can be explained.

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11-593
II. MSAD Program Tasks _ Ground-based Research Discipline: Materials Science

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TASK SIGNIFICANCE:

The results from this research are anticipated to yield a re',distic model for nucleation and crystal growth processes

occurring in glass-froming melts, which would provide not only an improved scientific understanding for these

processes, but also allow a more accurate quantitative analysis of the thermal analysis data, This would help to

explain several anomalous experimental results obtained for the kinetic parameters for crystallization and would lead

to values that are more physically interpretable. The relative role of heterogeneous and homogeneous nucleation on

glass formation can be determined, and the reported observation that a glass prepared in low gravity is more

homogeneous and more resistant to crystallization than an identical glass prepared at 1-g can be explained.

PROGRESSDURINGFY 1994:

1. An experimental method that uses differential thermal analysis (DTA) was developed for determining the

nucleation rates at different temperatures for a lithium disilicate (LS2) glass. The DTA peak height for

homogeneously nucleated LS2 glasses was compared with that for glasses containing different amounts of platinum.

The only assumption made in developing this method was that the crystal growth rate on a heterogeneous nucleus

was essentially same as that on a homogeneous nucleus. Nucleation rates for the LS_. glass determined by the

present method are m excellent agreement with those reported in the literature. The validity of this method is now

being tested using computer modeling developed by Dr. K. F. Kelton at the Washington University in St. Louis.

2. The effect of Particle size on DTA peak parameters (height, temperature and width) was experimentally

established for thr LS 2glass. Analyzing the data as a function of particle size, it is possible to predict the dominant

growth mechanism (bulk or surface) that occurs during crystallization of a glass. The DTA peak profiles for the LS2

glass as a function of particle size indicated a considerable contribution of surface crystallization, which was also

observed in the scanning electron microscopy (SEM) for the crystallized glass particles. The computer programs

developed by Dr. K. F. Kelton were modified to take account the effect of surface crystallization, and a significant

improvement in the calculated DSC peak profiles was observed for the LS2 glass.

3. An experimental method was developed to determine the nucleation rate-like curve for the LS2 glass from

dielectric constant measurements. The dielecric constant was measured at 1000 kHz for samples of about 2 mm

thick and 8 mm in diameter after prenucleation and crystallization treatment at different temperatures for different

times. The plot for the inverse of dielectric constant as a function of nucleation temperature yields a curve similar to

that of the nucleation rate curve for the LS2 glass.

STUDENTSFUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASKINITIATION: 12/91 EXPIRATION:12/94

PROJECTIDENTIFICATION:962-26-08-08

NASA CONTRACTNO.: NAG8-898

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Huang, W.. and Ray, C.S. "Nucleation rate curve for a Li:O.2SiO 2 glass by dielectric measurements." 96th Annual Meeting

of the American Ceramic Society, Indianapolis, IN, April 24-28, 1994.

Narayan, K.L., Cull, T.S., Kelton, K.F., and Ray. C.S. "Heterogeneous nucleation in lithium disiticate glass." 96th

Annual Meeting of the American Ceramic Society, Indianapolis, IN, April 24-28, 1994.

Ray, C.S. "Kinetics of phase transformations in glass forming melts." NASA Microgravity Materials Science

Conference, Huntsville, AL. May 24-25. 2994,
The Effects of Microgravfty on Vapor Phase Sintering

PRINCIPALINVESTIGATOR:Prof. Dennis W. Readey Colorado School of Mines

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to develop an improved understanding of solid sintering by investigating the effects

or reactive amaospheres and vapor transport on the sintering of ceramics. Ceramic systems that have been studied to

date show a wide range of behavior that is thought to be due to the close proximity of particles in powder compacts

appropriate for sintering and densification. The microgravity environment offers the unique opportunity to compare

behavior of dispersed particles, or particles with minimal agglomeration, with those in a dense powder compact.

These comparisons allow the separation of the relative contributions of particle interaction by gas phase diffusion

and coalescence controlled by grain txmndary, mobility.

TASK DESCRIPTION:

This research combines a study of the effects of vapor transport in powder compacts with those of dispersed

particles. Ideal systems for space-based experiments will be detemuned from initial ground-based research. First,

such an ideal system must exhibit significant microstructural effects of vapor transport. Second, the ideal system

must show a difference in behavior between constrained particles in close proximity such as those in a typical

ceramic powder compact compared to dispersed, unconstrained particles. Finally, an ideal system would be one that

could be used at low temperatures, would not revolve toxic materials or atmospheres, and would be amenable to

short-time experiments. The latter would allow experiments to be performed in drop tower or aircraft parabolic

maneuvers.

TASK SIGNIFICANCE:

The significance of this research is that it will lead to:

1. An tmproved understanding of solid state smtering of ceramics.

2. An improved understanding of the conmbutions that various transport processes make to microstructure

development during the sintering of ceramics.

3. Will provide infonnauon lor the design and production of porous ceramics through enhanced vapor phase

sintering.

The latter is particularly important from a technical point of view since materials such as AI203 are being sintered to

a controlled pore size and porosity for filter applications and for infiltration to form interpenetrating ceramic-metal

composites.

PROGRESSDURINGFY 1994:

In virtually all the systems studied, the most significant result is that the main effect of enhanced vapor transport on

sintering is significant particle coarsening with virtually no densification. The results of Fe203 in HCI illustrate

the point. In HCI, the following reaction dominates the transport species in the gas phase:

Fe203(s) + 6 HCl_g_=2 FeCI_I_I + 3 H20!g 1.

I1-595
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

i* i i * i t i, Ii * I I, i I i* ii, *,, ¢ _, ¢ *, *s i * * * * i !, i !. I I ¢ Ii I I I ! * * I | i i I* I * I ii I I I I i, ¢ !,, I| i I i, i ii * H | I * ! I *I I ¢ I I I s * I I J I i, | s* * i| * | I I P! I 0111 * | I i | * I i I 01 | | * I | * i * * i | i * | I * * I Io i i,, i i | i i I t I * ii * I I | | * I | I I I || * i! ! I I | | i | i H ! * | | I | | ! I | I i I I i|11 |, I ¢ _ I ! I | | * | i * | ! * * I_1 H _ _* i

This results in grain growth with essentially no shrinkage. The particles grow with very close to a t_3 dependence

and the particle size is within a factor of two calculated from classical Ostwald ripening models, t,23, FeEt3 fits the

model of coarsening by vapor phase diffusion reasonably well. However, A!203, which reacts in a similar fashion

in HCI, does not follow a t_/3dependence, the particle size is much smaller than predicted by the models, and the

apparent activation energy for the process is almost an order of magnitude higher than what would be expected. The

reason that ALO3 is thought to not fit the model is that coarsening is inhibited in this system because of low grain

boundary mobility. Theretore, even with rapid vapor transport, coarsening cannot occur unless grain boundaries are

mobile. This is due the constraints on a particle in powder compact by its nearest neighbor particles. If the

particles were not constrained but dispersed, boundary mobility, would not be a necessary condition for coarsening.

MICROGRAVITY EXPERIMENTS

The potential for microgravity in these studies is to provide an environment where particle coarsening can take place

under relatively dispersed conditions and compare the results of coarsening of dispersed particles with those in a

powder compact. Of course, some agglomeration of these small powder particles will occur in microgravity.

However, the degree of agglomeration and the constraints of nearest neighbors will be minimized compared to the

constraints of the typical compacted powder during sintering.

The times for previous coarsening experiments have been as long as hundreds of hours. This implies that for these

experiments to be successful, shuttle flights will be necessary. As a result, it is desirable to eliminate toxic or

explosive atmospheres such as HCI and hydrogen. Furthermore, experiments at lower temperatures are much more

amenable to microgravity experiments than the 1200°C to 1600°C temperature range that has been used in the past

tbr experiments with ceramic powders. As a result, it may be possible to use a low temperature surrogate to

investigate the same phenomena that are important at high temperatures in toxic atmospheres in ceramics. The

desirable characteristics of such a low temperature surrogate are:

• high vapor pressure

• low melting point

• simple crystal structure

• non-toxic

• stable in air

• small particle size

• shows particle growth and no densification

An additional benefit of low temperature surrogates would be the ease of measuring the gas diffusion coefficient and

the surface energy. These are two important parameters in vapor transport that are difficult to obtain for high

temperature ceramic materials and are normally estimated. Therefore, the initial phase of this research has/bcused

on finding suitable low temperature surrogate materials, both inorganic and organic.

INORGANIC SURROGATES

A list of some 50 potential inorganic compounds was compiled from the literature based on their melting points and

vapor pressures. The following systems were chosen for further experimental investigation based primarily on their

vapor pressures, melting points, and relative lack of toxicity. Iron Chloride, FeCl3 has a melting point of 304°C

and a vapor pressure above 100 Pa above 200°C. However, even in the arid Colorado climate, dry powder quickly

absorbed sufficient atmospheric moisture to become a puddle in only a few minutes. It was eliminated from further

study. Aluminum Chloride. AICl3 is similar to FeCl_ subliming at 180°C and the exposed powder did not seem to

be adversely al'fected by atmospheric moisture. However, x-ray diffraction showed that the chloride was reacting

with the atmosphere to produce what were probably hydrated chlorides or hydroxides. It too was eliminated from

further study. I_ine, I2 has a melting point of 112.9°C and a vapor pressure above 100 Pa above 38°C. However,

this vapor pressure is so high that it precludes observation in an ordinary SEM which is necessary to evaluate

particle growth in a powder compact. In addition, powders were not easily made so iodine was eliminated from

I1-596
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

n olanolulnaouJoonoolao| H ooaoooaoIaoa_oolH_aouaoI_uo_aoaaootaoiaoIuo_"_ioii|_no_noIootaoIni_ooa"_ii_iijnomoolaoj4o_"_ujl_miiau_j_"_giIa"aioao|_o|_oo_HoIiaioaon_ooi_o_oooaanaiiooo_aij_oo_oooo_on_ona_o_uoi_ooooi_ni_aooaog_ooaooaHao

further study'. Aimnonium bromide and aJmnonlum chloride. NH_Br, and NHaCI are very similar in behavior mid

offer the additional advantage or being able to form solid solutions to a greater flexibility in properties. NH4Br

sublimes at 396°C and has a vapor pressure in excess of 100 Pa above 195°C. NH4CI sublimes at 340°C and has a

vapor pressure in excess of 100 Pa at 160'>C. The as-received powders had a particle size greater than 100

micrometers and ball milling was not very successtul in reducing the particle size due to the plasticity of these

compounds. Small particle size powders could be made by evaporation and condensation and by reacting NH3 mid

HCI. Loose powders were heated for various times at various temperatures and some particle growth was observed.

Sodium chloride, NaCIi is typical of most of the alkali halides in that its vapor pressure at its melting point of

801°C is only about 10 Pa, very near the lower limit where significant vapor transport might be expected.

However, NaCl was chosen for further study since previous sintering studies have suggested that vapor transport

was an important transport process during sintering. Preliminary. experiments on loose powders do indicate particle

growth but powder compacts shrink considerably. This indicates that vapor transport does not dominate solid

diffusion processes and probably eliminates NaCI from further consideration.

ORGANIC SURROGATES

Over thirty organic compounds were found in the literature that had high vapor pressures at low temperatures.

Many were eliminated because of their alleged toxicity and others simply because their melting points were too low

or their vapor pressures too high. An example of one such material is H20, ice. Although it has many desirable

features for this study, handling it below room temperature creates problems that are to be avoided.

Two systems were chosen for further study. S_dicylic acid, C711_O3has a nielting point of 159<'C and a vapor

pressure of 100 Pa at 113°C. Trans-cinnamic acid, C,_H,O_ which has a melting point of 133°C and a vapor pressure

of about 100 Pa at 127°C. Both of fliese materials could be successfully ball milled to produce small particle size

material for initial screening experiments. However, the very high vapor pressures of these matenals has precluded

their investigation by SEM. This has made particle size analysis considerably more difficult. A satisfactory replica

technique has now been found and microstructure changes iu powder compacts are now being studied. Particle

growth of loose powders has been observed and has been analyzed by optical microscopy.

CONCLUSIONS

The necessity for long flights and non-toxic atmospheres has led to a search tar suitable low temperature surrogates

to study vapor phase sintering of ceramics. There are several inorganic and organic compounds that appear

promising. The very high vapor pressures at low iemperatures for some of these compounds preclude the use of

standard electron microscopy for an',dyzing the particle growth, eidmr dispersed or in powder compacts.

FUTURE WORK

Particle growth expertments will continue with ammonium chloride, salicylic acid, and cinnamic acid in both

compacts and with powders dispersed on glass w_x)l. In addition, experiments are being initiated with MgO, ZnO,

and AI203 powders in compacts and dispersed on graphite in both HC1 and inert aunospheres. These systems are

known to undergo particle growth in HCI m a powder compact. To be appropriate for microgravity experiments,

they must show greater growth a,s dispersed particles on the graphite compared to the constrained particles in a

powder compact.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 12/92 EXPIRATION: 12/95

BS Students: 0 PROJECT iDENTIFICATION: 962-26-05-08

MS Students: 2 NASA CONTRACT NO.:NAG3-1409

PhD Students: 0 RESPONSIBLE CENTER: LeRC

i i i i i i i ii iI I I I I I i i i i i i i i i ii i I I I I i i i ii I I I II I I I i i I i i i i i i i iI i i I i i i i i i I i li i i I i i I i l i i l iI I I I I I i i i ii ii i ii i III I ii i ii ii I I I I I I I I I II Ii I Ii tl i ii i i i i i i ii I ii i i i ii i i i i l ii i i i i i i i i i i i li i i ii i i i i i i l i i II I ii i i i i i i l i i i i i i i i ! i i i i ii i i l I i i i i i ill ii I ii i ii i I II I I II I I I i I i i i i

II-597
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

| ill i i | i| e H i ! i gi i! i | J i | I g I! g i I !| ii i I ! ¢ |! e ! i a o in m |III 111 |! t | i | I t, __ | | ! | i I ! ii ! ¢ n i_ I I | I i | I J I | || ni QH * I i s |! * ii i I I I | i | ! o I i ii ¢ I! o Di | | t ¢ ¢ I ! * I I II I! * I I o I ! g e I I e I I | I Is ii ! * Is I I s| s s | | is ¢ |! s I s | | s s ! s s Is s s so s s l II s o411 s s s s s s Is Is s s s s s N ! ig m n¿ m |Is I Is o IH I Io

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

J. Westhoff and D.W. Readey, "High vapor pressure compounds for modeling of vapor phase sintering." 96th Annual

Meeting of the American Ceramic Society, Indianapolis. IN, April 27. 1994.

Larson, J. and D.W. Readey, "Low temperature modeling of vapor phase sintering." 96th Annual Meeting of the American

Ceramic Society, Indianapolis, IN, April 27, 1994.

Readey, D.W., Larson, J., and Westhoff, J., "The effect of microgravity on vapor phase sintering." Microgravity

Materials Science Conf., Huntsville, AL, May 24 & 25. 1994.
Modeling of Detached Solidification

PRINCIPALINVESTIGATOR: Dr. Liya L. Regel Clarkson University

CO-INVESTIGATORS:

W.R. Wilcox Clarkson University

TASK OBJECTIVE:

The long term objective of the proposed research is to develop techniques to realize detached solidification reliably,

in order to produce crystals with fewer defects. To achieve this objective, it is necessary to understand the

mechanism for detached solidification. It is the primary objective of the research to further this understanding.

TASK DESCRIPTION:

A quantitative theory for detached solidification will be developed. Because the radius of curvature of the ampoule is

large compared to that of the meniscus, we will assume the ampoule wall is fiat and of infinite extent. That is, we

reduce this to a two dimensional problem. The pressure difference across the meniscus is related to its curvature by

the Laplace equation. In fact the radius of curvature must be constant, so that the meniscus is an arc of a circle.

The meniscus contacts the ampoule wall at the equilibrium contact angle. The meniscus angle at the conner of the

growth interlace is arbitrary, but determines the growth direction. Thus one can assume an infinitesimal gap as a

beginning and easily trace the path of the growth interface for given values of melt-ampoule contact angle,

melt-vapor surface tension, pressure difference, and the angle between the growth direction and the meniscus at the

freezing interface. We will develop an equation for the steady state gap width. From an estimate of the minimum

stable gap width, we will be able to specify the conditions under which detached growth occurs.

One critical parameter is the pressure difference across the meniscus. We will estitmate this pressure difference

based on a numerical calculation of diffusion of dissolved gas as it is rejected by the growing solid. We will

consider a finite ampoule diameter, an ideal mixture, and an ideal gas. This will enable us to estimate the residual

acceleration (g level) required in order to achieve detached growth.

As a consequence of our new understanding of detached growth in space, we have developed a concept for achieving

it on earth. Basically, a melt is supported by a piston at the bottom, in order to provide the pressure difference

condition required to give an appropriate meniscus shape and gap width. Because of the density change and the

diameter change that occur upon freezing, the piston must be moved continuously to maintain the proper meniscus

shape.

This has some resemblance to Czochralski growth, except that the solid is sealed in the ampoule and it may be

more difficult to control the crystal diameter. What we propose doing is a simple proof of concept experiment with

a low melting metal, such as tin. This will enable us to observe optically the solid detachment, meniscus

formation, and solidification. A simple upside-down Bridgman apparatus will be fabricated with transparent heaters.

The piston will be driven by a motor whose rate of motion is controlled by the human observer. The heaters will

be lowered by another motor in order to cause solidification downward. The inteffacial region will be videotaped

through an appropriate lens.

Temperature measurements will be made in the ampoule during some runs. Thermocouples will be inserted from

above and held in fixed positions during the run.

A flight experiment will be planned to test our model. If our model is correct, silicon will not display detached

growth in space. Although the contact angle of molten silicon on quartz is large, the adhesion of solid silicon to

quartz is extremely strong.

i I nni I I I I II I ! I | ! I | t I | I I II I I I I I I I e| I II I | I I I I I I nI I II I I n| | I I i i I I I l I ni I I t I I I I I I eI ni |I I nnn| I I I II II eI I I nI I I lI II I I I I I I I I Ii n!I I ni nni nnI i nII I I I; I oI I I I II i nni I I mI I I I I I nnI I nni nn| I ni | I I I | I n| i nI II I | ni nnI | I | I I II I I I I I oi I I I n| inoI neI I I I I II I I | I | I I I I I |I I I I I I I I I I I |

II-599
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

..,l,lam o olllll_|a,ll_¢_aolall.lallllll,l,|u a,llalaoll,,.m ,,i.,l.lalulg*t .,1*o,oo_,oIH,l*,luaool,o,,a.a_,lou o aloolu,,a,,oHaD01oo J. H*,.,,,ol,, H,l,ola..ao| H O,,*H OO_|OIH,,ool,*iaH*onl|llal'Ogna''lOIHH i i,,,a,iaml| H|I,_,,,,||

TASK SIGNIFICANCE:

Solidifmation in space has often yielded crystals that were smaller in diameter than their ctmtaining mnpoules.

When this occurs, crystals of much higher perfection are produced. We now understand how this occurs and why

crystal perfection is greater. This research project aims to put this understanding on a finn basis so that detached

solidification can "always be achieved. The research should _dso yield improvement-s in crystal growth on earth.

PROGRESS DURING FY 1994:

l. Recruited M.S. student in chemical engineering m September 1994.

2. Began derivation of equations for meniscus shape.

3. Began design of experiment.

STUDENTS FUNDED UNDER RESEARCH:

BS Students: 0

MS Students: 1

PhD Students: 0

TASKINITIATION: 6/94 EXPIRATION: 6/95

PROJECTIDENTIFICATION:962-21-08-21

NASACONTRACTNO.:NAGS-1063

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Arnold, W.A.. Regel, L.L., and Wilcox, W.R. Thermal stability during rotation in space: a scaling and numerical

analysis. Acta Astronautica, vol. 30, 357-367 (1993).

Derebail. R., Wilcox, W.R., and Regel, L.L. The influence of gravity on the directional solidification of indium

antimonide. J. Spacecraft & Rockets, vot. 30, 202-207 (1993).

Zbou, J., Larousse, M.. Wilcox. WR., and Regel. L.L. Directional solidification with ACRT. J. Cryst. Growth. vol. 128,

173-177 (1993).

Books

Derebail, R., Arnold, W.A., Rosen, G. J., Wilcox. WR., and Regel, L.L. "HIRB - The Centrifuge Facility at Clarkson" in

"Materials Processing at High Gravity." Edited by: L.L. Regel and W.R. Wilcox Plenum Press. NY, 1994.

Domey, J., Aidun, D.K., Ahmadi, G., Regel, L.L.. and Wilcox. WR. "Numerical Simulation of the Effect of Gravity on

Weld Pool Shape" in "Materials Processing at High Gravity." Edited by: L.L Regel and W.R. Wilcox Plenum Press, NY,

1994.

Farbshtein, I.I., Parfeniev, R.V., Yakimov, S.V., Regel, L.L., Derebail. R., and Wilcox. WR. "Analysis of Impurity

Distribution by Galvanomagnetic Method in InSb Obtained under High Gravity Conditions" in "Materials Processing at

High Gravity." Edited by: L.L. Regel and W. R. Wilcox Plenum Press, NY, 1994.

Regel, L.L., and Wilcox, W.R. "Preface and Introduction to Materials Processing in Large Centrifuges" in "Materials

Processing at High Gravity." Edited by: L.L. Regel and WR. Wilcox Plenum Press. NY. 1994.

Presentations

Lal, R.B., Batra, A.K., Trolinger, J.D., and Wilcox. W.R. "Solution growth of crystals in low gravity." NASA

Microgravity Materials Science Conference, Huntsville, AL, May 24-25, 1994.

Lal, R.B., Batra, A.K., Wilcox, W.R., and Trolinger, J.D. "Growth of triglycine sulfate (TGS) crystals aboard the First

International Microgravity Laboratory (IML-1) ." 44th Congress of the International Astronautical Federation, Graz,

Austria, October, 1993.

Sun, J., Carlson, F.M., Regel, L.L., Wilcox, W.R.. Lal, R. B., and Trolinger, J.D. "Particle motion in the fluid experiment

system in microgravity." 44th Congress of the International Astronautical Federation. Graz, Austria, October. 1993.

Wilcox, W.R., Regel, L.L., Cai, W.L., and Rydzewski. J.H. "Influence of gravity on the microstructure of the MnBi-Bi

eutectic." 44th Congress of the International Astronautical Federation. Graz, Austria. October, 1993.

_uo_|oi_o_toao_n_aoo_ooeeo_q_e_ie_o_eo_a_o!|o_a_!_o!_no!_o!_|oo_o!eo!oo*_o||o_!onoo_oo_o_aoo_o_ao_o|_o_a_o_ao|oa!o|no|_n||!a|_o_o*o_o_|a|_o_o!e_loo!o_!|o_u|_|!oo_o!_!|nolo_a_o_|o|_a_!a_|oe_to|o_o|_

II-600
Electrostatic Containerless Processing

PRINCIPALINVESTIGATOR:Dr. Won-Kyu Rliim Jet Propulsion Laboratory (JPL)

Co-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The Electrostatic Containerless Processing Task objective is to investigate thermophysical properties, nucleation

kinetics, and metastable phase selection from undercooled metals, semiconductors, and glasses by utilizing the

advanced capabilities of isolating molten drops in a clean environment provided by the High Temperature High

Vacuum Electrostatic Levitator.

TASK DESCRIPTION:

The High Temperature High Vacuum Electrostatic Levitator (HTHVESL) has been developed at JPL and has

important capabilities for the containerless materials science research. There are other methods of isolating liquid

drops such as the electromagnetic and acoustic levitation methods. However, the HTHVESL combines the

following important capabilities required for the various thermophysical property measurements and for the studies

of solidification processes: (a) it provides quiescent and clean processing environment without inducing convective

flow in the melt, (b) both conducting and non-conducting materials can be levitated, and (c) sample temperature can

be independently controlled without being affected by the levitation force. With additional capabilities of measuring

temperature, specific heat to hemispherical total emissivity ratio, thermal expansion coefficient, surface tension,

viscosity, and electric conductivity, this system is well suited for the containerless materials science research both

in the ground laboratories as well as in the micro-gravity environment.

TASK SIGNIFICANCE:

The capability of levitating molten metals, semiconductors, and insulators in a clean and quiescent environment

allows us to investigate various thermophysical properties such as specific heat, total hemispherical emissivity,

thermal expansion coefficient, surface tension, viscosity, electric and thermal conductivity of undercooled melts. In

particular, the capability of processing semiconductors and insulators is very unique to the present approach.

Investigation of nucleation and solidification processes will not only increase knowledge which is fundamental in

physical processes it will also have important engineering application in designing a certain microstructure or a

metastable state (including amorphous phase).

PROGRESSDURINGFY 1994:

Major Technical Achievements:

A significant breakthrough has been made in the high temperature electrostatic levitation technology. About 3 mm

size samples with varying density could be levitated against gravity with excellent stability and the sample could be

subjected to a required thermal cycle in a high vacuum environment. For example, high temperature processing has

been demonstrated by allowing a number of nickel (1"==1728 K) and zirconium (T_= 2128 K) samples to go

through meitmg-superheating-undercooling-solidification cycles. Processing even higher "In,materials will be

achieved if the present heating system is improved.

The High-Temperature High-Vacuum Electrostatic Levitation Facility (HTESL) at JPL has been developed under

NASA's Advanced Development Activity (ADA) program, and it is being recognized as one-of-a-kind in the world

which is able to meet various challenges imposed by the high temperature containerless materials processing

community both at universities as well as industrial laboratories.

11-601
Thehightemperatureelectrostaticlevitatorprovidesthecapabilityofsuperheating, undercooling, andsolidifying

puremetals,alloys,semiconductors, glasses, andceramicsinacleanandquiescent environment. Whenalevitated

sampleismelted,onecanrepeatvariouspre-programmed thermal cyclesusingasinglesample, observingdifferent

responseineachthermal cycle.Theadvantages oftheHTESLoverconventional electromagnetic levitators(EML)

arethat:(i)it canaccommodatebroadrangeofmaterials, includingmetals,semiconductors andinsulators, (ii)

sampleheatingandlevitationdonotinterferewitheachothersothathesampletemperaturecanbevariedovera

widerange(fromroomtemperatureupto2000°Cusingapresentlyavailableheatingsource),(iii)employment of

feedbackcontrolprovidesquiescent samplepositioningduringprocessingwhichallowstomeasureaccurate

temperatureandsamplevolume,(iv)sampleprocessingisdoneinahighvacuumensuringpurityof samples, and

(v)itprovidesawidelyopensampleviewlotnoncontactdiagnosticmeasurements.

Variousamplematerialshavebeensuccessfully melteduringlevitation,forexample, pureelementssuchasZr,

Ni,Si,Cu,Ge,AI,Pb,Bi,Sn,In,andvarious"alloysandnonconducting glasses/ceramics havebeenmelted,and

thermophysical propertiesofseveral ofthesematerialshavebeendetermined. Specifictechnical capabilitieswe

havedevelopedarelistedbelow.

St}ecific heat/hemistgherical total emissivity: Specific heat is a very important thermodynamic parameter from

which all other parameters such as enthalpy, entropy, and Gibbs free energy can be determined. These quantities

measured in undercooled regions of various materials carry special tmplications for the studies of solidification

processes and for the selection of useful metastable phases. Purely radiative cooling provided by the HTESL allows

us accurate measurements of the ratio between specific-heat and hemispherical-total-emissivity. Therefore,

availability of one of these parameters will determine the other. Such measurements have been demonstrated in

nickel, zirconium, silicon and germanium over a wide temperature range around their melting points.

Idndercooling and nucleation: Since samples are processed in a high vacuum, greater undercooling can be achieved.

Furthermore, since there is no appreciable internal flow induced by the levitation force, one can safely rule out

possible dynamic nucleation. Indeed, our undercooling/nucleation studies consistently revealed single nucleation

mechanism in contrast to other equivalent data obtained either by an electromagnetic levitator or a drop tube.

Combination of a high speed imaging system and a pyrometer will allow us to measure the solidification velocity

upon nucleation.

Met&stable phases: Containerless approach of solidification using HTESL will be an effective way of achieving

high undercooling in molten samples, thereby obtaining metastable phases. Specilic metastable phase may be

selected by injecting a seed particle having a right phase. We have demonstrated metallic glass formation in some of

glass-forming alloys measuring critical cooling rate and determining the Temperature-Time-Transformation (T-T-T)

curves. Developing new glass forming alloys using HTESL will be a very productive area for the development of

industrially useful new materials.

_!lIgtf, l..ke_,_d]_: Spherical drop shape of melts levitated by HTESL greatly simplify surface tension measurements

with increased accuracy. In view of the fact that surface tension is particularly sensitive to even minute surface

contamination, HTESL operating in a high vacuum environment would be an ideal approach to the surface tension

measurements particularly of those chemically reactive high temperature materials. We have demonstrated surface

tension measurements in various pure metals, ",alloys, and semiconductors with great accuracy.

Thermal exoansion coefficient measurement: Accurate determination of mass density increases the accuracy of other

thermophysical parameters such as specific heat, surface tension, thermal diffusivity, kinematic viscosity etc.

Quiescent levitation as well as nearly spherical (or at least axi-symmetric) sample shape provided by HTESL oiler

an ideal situation for the measurements of mass densities as well as thermal expansion coefficients. An optical

system which produces high-magnigication/high-contrast video images was set up, and image processing software

was developed which measures the sample volume within 1% error. We are in the middle of testing this capability

using high temperature liquid samples.

Semiconductor processing: We have succeeded in processing both pure silicon and germanium samples. Having

isolated from container walls the silicon melt showed undercooling as deep as 250 K. Capability of processing

semiconductor materials for thermophysical property measurements is particularly important since these parameters

are needed in numerical modeling of crystal growth environment. We have also succeeded in measuring surface

tension of silicon melts over 400 K around the melting temperature.

I I II I I I I I I I I I e II a Is I 111 el I I I I a Ill II a I I I I Ill ill i I Ie i i I I I I i i I I I a I I II I I I I I i i i I I Ie iI I I I i I I I i s i i eI I I I I I I I I I iI a I 1 a i i a i i i 11o Ii a i i i I I I I I I Ii i i i i i i i i i i i I I i II I o } i I I I I I I I I II I I I I I I I I I I I I eI I I i I I I i I I I II I I I I I i n i ti ii i t I I I I I I II I I I t a e I I I I I ill i I I I I I I I I I I a II I a I t I I t

11-602
Viscosity: HTESL promises _m important possibility of measuring viscosity by observing the free "damping tune of

an oscillating drop. This will be possible only in the absence of appreciable internal flow as much a,,_ any

interference by the levitation forces. A preliminary attempt for viscosity measurement using a tin sample has

revealed that greater caution is required in order to increase mea,surement accuracy. Development of the viscosity

measurement technique using HTESL is in progress.

Electrical _md thermal conductivity: Some feasibility study have been conducted with promising conclusion,

however, development of these techniques will be subject to future funding.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/89 EXPIRATION: 9/94

PROJECT IDENTIFICATION: 962-25-04-08

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Rhim, W.K., S. K. Chung, D. Barber. K. F. Man. Gary Gutt. A. Rulison. R. E Spjut. An electrostatic levitator for high

temperaturecontainerless materials processing in l-g, Rev. Sci. Instru .. 64. 2961 (1993).

Rulison, A. and W. K. Rhim. Containerless measurement technique of specific heat and total hemispherical emmissivity

of refractory materials. Rev. Sci. Instrum. 65, 695 (1994).

Rulison, A. and W. K. Rhim. Specific heat to hemispherical total emissivity ratio for undercooled liquid nickel,

zirconium, silicon, and germanium. Metall. Trans. B, (1994 in press).

NASA Tech Briefs

Rhim, W.K. and S. K. Chung. High temperature electrostatic levitator. NASA Tech Brief. 18.62 (1994).

Proceedings

Rhim, W.K., S. K. Chung, D. Barber, K. F. Man, Gary Gutt, A. Rulison, R. E. Spjut. "A high temperature electrostatic

levitator for 1-g." Containerless Processing: Techniques and Applications. eds. W. H. Hoffmeister and R. Schiffman.

(1993 TMS Annual Meeting, Denver, Colorado, Feb. 21 - 25,1993) p. 27. 1993.

Presentations

Busch, R., Y. J. Kim. W. L. Johnson. A. L Rulison. and W. K. Rhim. "Determination of specific heat and total

hemispherical emissivity of the highly undercooled Zr41 :Ti,_Cu_:,Ni,0c,Bez:_ alloy." 95th TMS Annual Meeting, Feb.

12-16. 1994, Las Vegas, NV.

Kim, Y.J., R. Busch, W. L. Johnson, A. J. Rulison, and W. K. Rhim. "Undercooling studies of the bulk metallic glass

forming Zr,_ 2Ti]_sCu,:_Ni_0oBez:__ alloy during containerless elecm)static levitation processing." 95th TMS Annual

Meeting, Feb. 12-16, 1994. Las Vegas, NV.

Rhim, W.K. "High temperature ESL." 6th Space Station Utilization Workshop, Jan. 18-19,1994. Tokyo, Japan.

Rhim, W.K. "Materials processing by high temperature electrostatic levitation." Canadian Round Table Workshop on

Microgravity Containerless Processing, Feb. 24 - 25. 1994. St. John's. Newfoundland. Canada.

Rhim, W.K. and A. J. Rulison. "Thermophysical property measurements of undercooled silicon." 12th Symposium on

Thermophysical Properties, June 19-24, 1994, Univ. Colorado, Boulder, Colorado.

Rulison, A.J. and W. K. Rhim. "A non-contact measurement technique for the specific heat capacity of undercooled

metals." 123rd TMS Annual Meeting, Feb. 27-Mar. 3, 1994, San Francisco, California.

Szekely, J., W. K. Rhim, J. Watkins. "Critical assessment of electromagnetic and electrostatic levitation for

containerless processing in microgravity and under earthbound conditions." 123rd TMS Annual Meeting, Feb. 27-Mar. 3,

1994, San Francisco, California.

Patent

Patent In Process, U.S. Patent #: JPL New Tech. Report, Item No. 9063. Docket No. 19458 Rhim. W.K. and A. J.

Rulison. "Surface Tension and Viscosity Measurements of Molten Materials by Electrostatic Levitation."

_!_||e|_e!_||_!_!_*_|_'*!_|_*_!*_*_|_*_''_'Ill'_*_|!__*!|*!|'_*|_'_|_e_''_'_'**_'_*_|_|_'*_l_'_'_'|_|_||_||**_|_*_'|*'_*'_*_*'_H_*'_*_*_|*_''_'_

II-603
II. MSAD Program Tasks n Ground-based Research Discipline: Materials Science

t ! i o | I a o |n | | i |o I o o a o I I o o I o oi o II o ! i o I I o ot I o i a o i I o ii g o i i o | i Io o Io o II I | I o o i | o n I o | I oo i Io I I o | I ! oil o i !| i| | I I o | I ! I I o | io | I o | t | | I | | a oI I o o I a o i I o i Io I II | iIll i ! | a u o I ! o II o | I I mi o o o o o l o o Ia o | I o o i o oil o i a o i| o I I o I I ! I u e I I oo I | o o o o i o | i I o iI o ! o o t | o q o !i a o a I o t I o I | | il o iI I I

Drop Tube Operation

PRINCIPAL INVESTIGATOR:Dr. Michael B. Robinson NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective is to maintain and upgrade the operation capability of and to conduct experiments in the MSFC

105-meter drop tube. The drop tube facility includes, in addition to the tube itself with the associated pumps and

valves, such items as furnaces, levitators, other sample holding or handling devices, and data recording systems.

This research includes the operation of a facility laboratory located at the facility. This laboratory includes furnace

test facilities as well as pyrometer calibration platforms.

TASK DESCRIPTION:

This research covers work in the area of defining, developing, and conducting experiments using the low-gravity

capabilities of the drop tube. Such experiments may be in themselves complete investigations to develop new

knowledge or to prove theories, or they may serve as precursors for more extensive experiments to be conducted in

space. This research also includes studies and experiments to define the effects of various levels and durations of

acceleration perturbations on microgravity experiments.

The research approach will be to:

• Study the limits of undercooling in a low-gravity containerless environment and ascertain if nucleation occurs

homogeneously at the undercooling limits.

• Evaluate the effects of deep undercooling by containerless processing on resulting microstructure and de/hae and

understand the types of phases formed, their shapes and sizes, and their distribution, abundance, composition,

homogeneity, and substructure.

• Study the tbrmation of quasicrystalline material through deep undercooling.

• Study the spreading of liquids as a function o£ undercooling in order to better understand the thermophysical

properties of materials.

TASK SIGNIFICANCE:

This research activity is an essential part of a successful program of research in microgravity science and

applications. Many experiments proposed for flight on the Space Transportation System (STS) can be developed

and tested in preliminary form using drop facilities. This can result in significant savings through the proving of

experiment concepts and equipment designs before proceeding to much more costly space flight hardware. It also

provides additional data that can be compared with data obtained from the space flight experiments. And in some

cases, the data obtained from the drop tube or aircraft experiments prove to be sufficient to satisfy the experimenter's

requirements, thus obviating the need to proceed with an experiment on the STS. The result is an overall savings

in the cost of conducting microgravity experiments while adding to the scope and quality of the results obtained.

I I o! II! l! Il l I I Ill ! ! I oooI ooo! ! ol I l I ! l eoeoi oi oi II I ooI l looIll I ii Ill l ! I I !! I OI l I I I Ill l! I !! l I ! OI I ! aI gI I! l le I II ! ! oI I OIII ! I ! ! l I I I !oI ! oI ! l ! ! I ! !I II I l I l l I I oI l I Oog l oI nlo! nloOI ! ! I I oi I! I l ! ! l ! ! oI ! oI! l I ! oe! I Ill lI I II l I oI I I l l oOI IaoI ! Oil I oOI I! l I I I aI ! I I! OI I I I l I Io I Io

II--604
[I. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

"n_|_|_|_i|_M_o|_|I|_|_nn_i_IlluI_!_i"n"n|m_|"_I_"iM_"_H_In1_|_| H il.l.ll*nl.;llnnlll.n HIHIII|Ill .IIHIHIIIIItl;IIIHIHtnnlIIIIOHHII0||IIIIIIlUlHII.IIIlUlI_IIII0U .ll|lllllll|lolll_._ll

PROGRESSDURINGFY 1994:

During FY94 approximately 400 samples were processed, the majority of which was in support of the IML-2 flight

of TEMPUS. In addition, numerous improvements were implemented, including the installation of a black tube

liner which will eliminate stray rellcctions. These rellections are a major source of error m nucleation temperature

measurements.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 1/78 EXPIRATION: 1/95

PROJECT IDENTIFICATION: 963-80-10-02

NASA CONTRACTNO.: In-house

RESPONSIBLE CENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Morton, C.W., Hofmeister, WH.. Bayuzick. R.L, and Robinson, M.B.

phenomena. Mat. Sci. & Eng., w)t. A178. 209-215 (1994).

A statistical approach to understanding nucleation

Presentations

Bayuzick, R.J., Hofmeister. W.H., Morton, C.W., and Robinson, M.B. "Effects of nucleation by containerless

processing." NASA Microgravity Materials Science Conference. Huntsville, AL, May 24-25. 1994.

Rathz, T.J., Weimer, J.J,, and Robinson, M.B. "Undercooling of immiscible metal alloys without crucible-induced

wetting and nucleation." Alabama Materials Research Conference, Tuscaloosa. AL, September, 1994.

I I I I II Ill eli I ill I aI lea I III Ill I el I lilll I I Oil Oil ill ell I I aills llilt OOOI I I I I I I OI I III el* I el I II eel I oI Ill Ill III I Ill I I I I II II III I l I lOllS eI I el III I II I eI II I, I IoI I I I II I I* I ISI Ill I Ill III I I Ili I I I I I I I II I OI I I I I l I sI I I II li I I * I I * aI I I I I IIll III I II III Ill I I I I I OIll II oI I

11--605
Measurement of the Optical and Radiative Properties of High-Temperature Liquid Materials by

FTIR Spectroscopy

PRINCIPALINVESTIGATOR: Dr. Michael B. Robinson NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

S. Khrishan

T. Rathz

G. Workman

CRI

University of Alabama, Huntsville (UAH)

University of Alabama, Huntsville (UAH)

TASK OBJECTIVE:

The objective is to fully develop the use of FUR spectroscopy for the purpose of determining, at a high rate of

speed, the normal and total hemispherical emissivities of deeply undercooled materials over the wavelength range of

2 to 20 microns. Due to the nature of the approach, the spectral emissivites can be determined quickly over a wide

wavelength range and applied over a wide temperature range.

TASK DESCRIPTION:

The task will involve development of the technique of measuring the radiative properties of high-temperature,

highly reactive materials in the liquid and undercooled liquid state by use of FTIR spectroscopy. The sample will

be positioned in a Containerless environment by either electromagnetic or electrostatic positioners. The technique

offers the advantage of fast measurement so that sample temperature stability will not present insurmountable

problems.

TASK SIGNIFICANCE:

Optical property measurements are essential to the understanding of the behavior of liquids at high temperature.

Accurate knowledge of these properties provide an ability to validate theories of nucleation, solidification, and

undercooling: and provide the basis for accurate non-contact temperature measurement. They are particularly needed

for accurate measurement of high temperatures so that existing and new thermophysical property measurements can

be interpreted correctly.

PROGRESSDURING FY1994:

All necessary equipment has either been designated or ordered. Designs have been finalized and construction of the

FTIR system and processing chamber should begin shortly.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 9194 EXPIRATION: 9196

PROJECT IDENTIFICATION: 962-25-08-32

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC

I l l ita l el eI i ol I al l I I l I I I I l I ol l I l I I I I I I I I II i I I I I I I i i I I I I I II I I I I I I I I II I I I I l I I i i I II i i i i i i i i i I II I II I I I I I I I I I l I II I II I I I I I I I i I l i II I I I I I I i I I I II I II I I I I i i I i I I I I I II I I I I I I I I I I I II l lil i l I I I I II I I I I I I I I I I I II I II I I I I I I I I II i i I I l i I i i I i i II i i i i I l i I II Ii I I I I I I I I I II I I

11-606
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

ii.noH oH o o H olaululuanloooaou o o .oH n "a_a_I"iu_i|oa"i"la$I"i"moi_ajna_a_u_"ao_omaoo"_onIa_n"_ooou"loinai|un_a"a J|l.l.lullalla.a.l.nolloonl_uool;.H| H_I.IIHn.HolaoH.IoI_a.a.a--HO_--IUOoo--aoo;

Undercooling Behaving of hnmiscible Metal Alloys in the Absence qf Crucible Induced Nucleation

PRINCIPALINVESTIGATOR: Dr. Michael B. Robinson NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

D. Frazier

B. Facemire

T. Rathz

G. Workman

NASA Marshall Space Flight Center (MSFC)

NASA Marshal Space Flight Center (MSFC)

University of Alabama, Huntsville (UAH)

University of Alabama. Huntsville (UAH)

TASK OBJECTIVE:

The objective of this effort is to determine it"processing immiscible metals in a contamerless environment would

alter the critical point wetting mechanism and the extent to which this would lead to changes in the subsequent

nucleation kinetics. If the nucleation kinetics are suppressed enough to allow bulk undercooling, the nucleation

recalescence will be measured. In addition, the droplet surface conditions can be vaned by processing in a vacuum

versus a gas environment to alter the surface composition and thereby the wetting potential of the fluid phases.

TASK DESCRIPTION:

Research in a containerless, low-gravity environment provides much information as to whether preferential wetting

of the free surface occurs and more importantly whether it can be controlled. The MSFC 105 Meter Drop Tube

Facility will provide the low-gravity, containerless environment necessary for this study.

TASK SIGNIFICANCE:

Cooling of monotectic alloys into the miscibility gap will lead to nucleation of droplets with in the liquid matrix.

Previous earth and space experiments have concentrated on the morphology of the bulk microstructure by

attempting to control the convective-diffusive flow of these droplets with the proper selection of the crucible

material and thermal fields. Immiscible metal systems have as yet not been studied in a containerless environment,

eliminating crucible induced flows,

PROGRESSDURINGFY 1994:

Six different systems have been identified for initial investigation. Starting samples have been generated and will be

soon processed in the Drop Tube Facility. Preliminary investigations of the microstructures of the as cast materials

has begun.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 9/94 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 962-25-08-33

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC

I Ill l 1lOll l I I I Ill II I Ill l lllllllll Ill Ill I I I l lll III Ill Ill lifo Ill I I II I I el I Ill III Ill III I i I i ii i11 II Ill l II I iI Ill l I I l ii i I Il I I I I I l I I I I Ii i ii l i ii i i i i i I I I I I II I I I I IS I I I I l II l III I I i i I i l i i l I I Il I II I I I l I I I I I I I I I ii l i i i I I I I I i i ii i i i i i i i i i i il I i l i i i I I I I I I i i II I I l I I I I

11-607
Undercooling Limits in Molten Semiconductors and Metals: Structure and Superheating Dependencies

PRINCIPALINVESTIGATOR:Dr. Frank O. Shi University of Calitomia, lrvine

CO-INVESTIGATORS:

W.K. Rhim

A.J. Rulison

Jet Propulsion Laboratory (JPL)

John Hopkins University

TASK OBJECTIVE:

The objective of this work is to study the onset of nucleation of crystals and thus the undercoolmg limits for melts

of semiconductors and metals in order to experimentally test and further develop a model for the onset of

nucleation.

TASK DESCRIPTION:

The undercooling experiments are pertbrmed using the existing High Temperature Electrostatic Levitator. The

HTESL is fully operational and has proven to be effective in melting and undercooling metals, e. g. zirconium and

nickel, semiconductors, e. g. germanium, and ceramics, e. g. silicon dioxide based glass-ceramics. The HTESL is

fitted with a single color pyrometer which are used to measure the undercooling limits of all the s_unples.

TASK SIGNIFICANCE:

The onset of nucleation in the undercooled liquids and thus the achievable undercooling level determines the

selection of the final microstructures and formation of metastable amorphous phases. The ability to predict and

control the onset of nucleation is theretore important in advanced materials processing.

PROGRESSDURINGFY 1994:

The necessary contractual arrangements are still being processed to fund this project which was accepted under the

1993 NRA-93-OSSA-12.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 10/94 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 962-21-08-22

NASA CONTRACT NO.:NAGS-1082

RESPONSIBLECENTER: MSFC

I I I l iii lll IIl lllll 1o ill lie lea ISllll Ill Ill lea Ill IIi III In I iiii III ii l II lllllll Iii IIi iiiiii III III III II i iii III I Ill III III III III II IIII III II I II I IIIIII i II IIII III III I iii i II iii i iii iii iii i i i i ii ii i iii ii I III ii i iii iii iii iii itl iii iii iii ii IIi ii i ii i i I I I I I iii IIi I

11408
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

Crystal Nucleation, Hydrostatic Tension, & Diffusion in Metal and Semiconductor Melts

PRINCIPALINVESTIGATOR:Prof. Frans A. Spaepen Harvard University

CO-INVESTIGATORS:

M.J. Aziz

D. Turnbull

Harvard University

Harvard University

TASK OBJECTIVE:

The objective is to develop basic understanding of the phenomena and processes that are central to the microgravity

program: crystal nucleating, glass formation, and diffusion in the liquid state.

TASK DESCRIPTION:

Crystal nucleation is studied in elemental metal, semiconductor, or quasi-crystal-forming droplets coated with

different fluxes, droplets with clean surfaces in vacuum, and droplets solidified in a drop tube. The effect of

hydrostatic stress on the nucleation kinetics is studied by dilatometry. The crystal-melt interracial tension is studied

experimentally and theoretically. The diftusivity in the liquid state is measured from the broadening of unpurity

profiles a/ter pulsed laser melting.

TASK SIGNIFICANCE:

Studies of the undercooling of liquids and the kinetics of crystal nucleation are an important category of experimenLs

that exploit the containerless environment provided by microgravity. Our work, ground-based, is aimed at

advancing the understanding of the fundamentals of undercooling, nucleation, and glass formation; at exploring the

potential and limitations of ground based alternatives such as fluxing and drop-tube processing; and at exploring the

potential of ground-based containerless processing facilities provided by the microgravity program.

PROGRESSDURING FY 1994:

Work on the undercooling of semiconductor melts is continuing. Undercooling experiments on silicon droplets

have been pertormed in a variety of oxide and halogen fluxes. Much effort was devoted to the development of an

appropriate flux. Chloride and fluoride fluxes were too volatile at the high temperatures required to melt silicon.

Many oxide fluxes, such as B20_ which is very effective tbr undercooling liquid germanium, are reduced by silicon,

and as a result lose their effectiveness. This leaves SiO2, Cad, Bad, AI:O_, TiO,, and MgO and few others. At

the same time, the flux must be sufficiently fluid at the undercooled temperatures to be effective.

A systematic study of the ternary and quaternary alloys of the chemically compatible oxides revealed that molten

47.5% SiOv 39% Bad, 13.5% Cad was an appropriate flux. The first three undercooling experiments gave two

large undercoolings of 350 K and 310 K. These are the largest undercoolings measured in bulk liquid silicon; the

previous maximum undercooling was 285 K. This measurement requires a re-interpretation of the agreement

claimed between the observations of bulk undercooling and of undercooling lollowing pulsed laser melting.

In a parallel series of experiments, melting and resolidification of uncoated silicon and germanium on different

substrates were investigated with the aim of developing a systematic understanding of the effects of heterogeneous

nucleants. Specific substrates included (with undercoolings listed) : amorphous silica (190-230 K), crystalline silica

(quartz) (60-160K), sapphire (30-55K). Substrates used for germanium included amorphous silica (120-170K),

crystalline silica (quartz) (110-140K), sapphire (70-120K), mica (140-150K), silicon (9-15K) and silicon with an

epitaxial layer of germanium (3-5K, i.e. zero within experimental error).

Considerable progress was made on the undercooling of melts that crystallize into polyhedral structures. The rebuilt

3m pyrex drop tube was used for solidification experiments on Ga-Mg-Zn droplets. This system is a known

quasicrystal former. The aim was to investigate the degree of undercooling this melt can sustain, given that its

11-609
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

ill| i|lll Jill ill JllJl|tlll|lJllll|lll0|lll!llJll|| |ll||s| Jlllllllllll!llll!ll|QIJillll|lllllll0111111|1011110||lll00 JDQOH||l|lHl!!0|10|ll|llllllSl||tlll!¢|!ll|lll*|ll Jlll10|l|0!l|llll_0_lll_ll_H*lllll_*l10Hlli|_||l_|lll_ll|||l|l|ll_l_*ll*

mterfaci',d tension with polytetrahedral phases such as the quasicrystal, the quasicrystal approximants, and

Frank-Kasper phases (such as the MgZn2 Laves phases) may be quite low. A large number of different sizes have

been solidified. A detailed study of their microstructure is underway, including phase identification and quantitative

characterization of the phase morphology. The ease of nucleation of the MgZn: phase, which we observed in earlier

work on undercooling of AI-Mg-Zn by different techniques, has been confirmed in this system.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 4/92 EXPIRATION: 3/95

BS Students: 0 PROJECT IDENTIFICATION: 962-25-07-07

MS Students: 0 RESPONSIBLE CENTER: JPL

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Spaepen, F, The temperature dependence of the crystal-melt interfacial tension: A simple model. Materials Science and

Engineering, A 178, 15-18 (1994).

Books

Spaepen. F. "Solid State Physics: Homogeneous Nucleation and the Temperature Dependence of the Crystal-Melt

Interfacial Tension." Edited by: H. Ehrenreich and D. Turnbull Academic Press. Inc. Boston, 47. pp 1-32. 1994.

Presentations

Spaepen, F. "The temperature dependence of the crystal-melt interfacial tension: A simple model." NAT| Advanced

Research Workshop on Undercooled Metallic Melts: Properties, Solidification and Metastable Phases, I1 Ciocco, Italy,

1994.

iiiIIaloIlIllIli, iiliiooIIioIlolIIiIIIliioieoIIoIIoIIlIIIliIIIiiitleIaiIilIiiiaIiIli IIsIIIIIIIo¢loIIolIoIIe loIIII IloIlIooIoilelll,Oiaiiiliioiieliolliee|o lI¢Ioiioaiiaill liai|osIooIieiiiio;io!Io;lIIieiioiiI IllIiiOil osioiiosooltiltol|i eill|lIll lie l

II-610
Micro- and Macro-Segregation in Alloys Solidifying with Equiaxed Morphology

PRINCIPALINVESTIGATOR: Prof. Doru M. Stefanescu University of Alabama, Tuscaloosa

CO-INVESTIGATORS:

L. Nastac

P. Curreri

University of Alabama, Tuscaloosa

NASA Marshall Space Flight Center (MSFC)

TASK OBJECTIVE:

The objective of this research is to extend the recently developed model tor microsegregation from a closed system

to an open system. This means that the new model should include the influence of (i) buoyancy-driven flow

(thermosolutal convection), (ii) of convection caused by the relative motion of the liquid/solid interface, and (iii) of

convection caused by density variation with change of phase, on both micro- and macro-segregation. The analysis

will be conducted only for equiaxed dendritic and eutectic ',alloys.

Microgravity experimentation will be used to asses the relative value of the three factors affecting solute

redistribution. The experimental work will be performed on the KC-135 aircraft for multi-directional solidification.

TASK DESCRIPTION:

The theoretical work will consist of the following tasks:

1. Develop a formulation to describe the rheology of the particular two-phase equiaxed systems of interest (dendritic

and eutectic);

2. Develop an analytical solution/'or microsegregation for the case of an open system;

3. Develop a formulation for thermosolutal and shrinkage flow that includes description of both macro- and

micro-segregation;

4. Couple the macro-transport to micro-transport through description of solidification kinetics;

5. Develop a numerical code to solve the above algorithm:

6. Evaluate the validity of the closed system microsegregation model for the case of low-g environment.

The open system model will be used in validation in conjunction with both high-g and low-g experiments. In

addition, by turning off the shrinkage flow and/or the solid-liquid relative motion flow, the relative effects of these

flows can be evaluated. The closed system model should come reasonably close to the low-g experiments.

Validation of the models will be done through experimental measurement of solute concentration at the macro- and

micro-scale level, and of the temperature distribution.

The equipment that will be used tor the experiments is NASA's Isothermal Casting Furnace that has a temperature

range of 100 to 1350 °C, and quenching rate capabilities of 1 to 50 °C/s. This fttrnace will be flown on the KC-135

aircraft. The samples will be melted before the low-g period of the flight, and solidified during the 25 s of low-g.

Parallel experiments will be conducted on ground.

TASK SIGNIFICANCE:

At the micro scale level, the assumption that mass transport is purely diffusive is quite reasonable, and thus, a

closed system may be a good approximation tot certain alloy systems solidifying under terrestrial gravity. This

assumption is even more valid when considering low-gravity (low-g) solidification. However, for most alloy

11--611
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

lllllllllllel Jlt11111111111.1.11|1||11| H iimlutllllllllllllllllllm i|l.lllllll |oIHIII¿I mlllllllllllll II¿lmlilmlIHIItllmlllllIH I IIIItlHIl|lnlUlHIIIIlllllll|l H IIII H IIlelll|al|aeH. H|ll|l.l|tlllallallal|allillll|lllllll

systems die influence of fluid flow caused by thermal and solutal convection cannot be ignored. During

solidification of a multicomponent "alloy, buoyancy-driven fluid flow occurs due to the temperature and

concentration gradients. Even in upward directional solidification it is difficult to avoid horizontal temperature

gradients since the container walls are not perfectly adiabatic. Accordingly, there is a need to further develop the

model to address the open system case.

PROGRESSDURING FY 1994:

Funding for this project has been received in the tall of 1994. Consequently work has started only recently. To date

a formulation to describe the rheology of the particular two-phase equiaxed systems of interest (dendritic and

eutectic) has been developed.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 8/94 EXPIRATION: 8/96

PROJECT IDENTIFICATION: 962-25-08-34

NASA CONTRACT NO.: Ncc8-059

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Nastac, L.. and Stefanescu, D.M. An analytical model for solute redistribution during solidification of planar, columnar or

equiaxed morphology, Met. Trans.. vol. 24A. 2107-2118 (1993).

I I! ! llll llllll III III nllllnl ill lllllll lll lll II i Ill III III iii l lll II I ii i ii i i I II I I i ii I l iii iii I ii iii iii |ii iii iii ii i ii iill ii l II I mi i ii i i i I I II II I ill i i i i i i i is i i i i I I II l I I I I I II I II Illll III III I II Ill Ill I I l I I l I II I II I II I I I I I I II I I I I I I I II I IS I I I I I I II III I I I I I I II I

11-61 2
II. MSADProgramTasks-- Ground-based Research Discipline: Materials Science

The hnpaction, Spreading, and Solidification of Partially Solidified Undercooled Droplets

PRINCIPALINVESTIGATOR: Dr. Julian Szekely Massachusetts Institute of Technok)gy (MIT)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The purpose of this project is to examine the spreading of molten metal droplets and their solidification upon

impacting onto a solid cooled surface.

TASK DESCRIPTION:

This project is aimed at studying the splatting and solidification behavior of undercooled and partially solidified

metallic specimens. The project consists of both an experimental component and a computational and awalytical

component.

In the experimental arrangement a levitated and inductively melted metallic droplet will be _dlowed to f',dl in the

Marshall drop tube. cool during flight, and then impinge on a chilled solid substrate. The flattened droplets will be

collected and analyzed. The thermal management of the system will be so arranged that upon approaching the

chilled substrate, the droplets will be undercooled in the range of 10-800 C, although, for some control experiments

we will impinge superheated droplets or droplets close to their melting temperature. Furthermore, a number of

experiments will be carried out, such that undercooled droplets will be made to impinge on the flat surface of the

substrate.

However, perhaps the most novel feature of the investigation is that for the experiments, immediately prior to

impingement of the droplet on the target, nucleation of the solid phase will be triggered by contact with one or

more of many spikes raised above the substrate. The height of the spikes will be such that the specimen will be

only partially solidified before impact.

Experiments to be run include impacts on a fiat target by non-undercooled drops for comparison to previous work

and undercooled drops to study the effect of the degree of undercooling on the stability (splashing tendency) and

final microstructure of the drop. The study will also include the effect of controlled nucleation on the liquid-solid

phase transformation by contact with a spike raised above the chill block. The occurrence of nucleation at a

controlled tune before impact will add a new dimension to the study of the competition between solidification and

spreading of the droplet.

The theoretical work will include the development of a new set of equations to describe the behavior of the partially

solidified droplet upon impact and the calculation of the rate of cooling of the specimen as it falls and the velocity

field in the specimen as it falls. In addition, we will address issues of impingement and splatting.

TASK SIGNIFICANCE:

The problem of the spreading and solidification of molten metal droplets is of both fundamental and practical

interest. The fundamental interest is provided by the fact that the simultaneous spreading and solidification of metal

droplets is a generic problem in materials processing. The practical interest is associated with the immediate

relevance of these phenomena to spray forming and the formation of coatings.

PROGRESSDURINGFY 1994:

This research was initiated in June, 1994, and at the present time, we have done preliminary calculations assessing

impact velocities and spreading times and have identified suitable candidate materials, which include ",aluminium,

copper, zirconium, titanium, and nickel. In addition, we are planning to use two glass forming alloys developed in

I1--613
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

.lllll_t illll_!ll|lullll011$111|llllllllll|lll|lll|llllllll¢|l JHllll.|tl|lmlltllll_ll J|llJllell|lll|llltlllll|ll!lllll01111tll |_e_|1_I_!_|_!_||_|_|!_||_|_!_!_|_|_|_!_!

Prof. W. Johnson's laboratory at CalTcch. We are hoping to initiate the first series of experimental runs at the

Marshal/Space Flight Center drop tower betore the end of 1994. For the subsequent set of experimental series, we

will initate the nucleation of a solid phase just prior to impact and will assess the dropping characteristics of these

materials.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 9/94 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 962-25-08-28

NASA CONTRACT NO.:NAG8-1069

RESPONSIBLECENTER: MSFC

_l____*_t_o_*D__*D_*_e____l_*_

II--614
Microporous Membrane and Foam Production by Solution Phase Separation: Effects of Microgravity

and Normal Gravity Environments on Evolution qF Phase Separated Structures

PRINCIPALINVESTIGATOR: Dr. John M. Torkelson Northwestern University

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this research is to develop a quantitative understanding of the microsmacture tormation in glassy,

polymeric microporous membranes and tbams produced via thermally induced phase separation. In particular, this

study will delineate the role of gravity (resulting in buoyancy-driven flows resulting in macroscopic layering of

phases) or the absence thereof in both the early-stage phase separation mechanisms, spinodal decomposition versus

nucleation and growth, and the later effects of coarsening, by Ostwald ripening and/or hydrodynamic flow.

Coarsening effects will be studied quantitatively by experimental determination of the growth in pore size over tune

as a function of quench depth, polymer molecular weight and concentration, surtace tension, etc.. in near-critical and

off-critical point phase separation processes. Comparisons to expectations based on Ostwald ripening and

hydrodynamic flow mechanisms of coarsening will be made. By developing a quantitative understanding of the

thermodynamics and kinetics of polymer solution phase separation processes, both in terms of gravitational effects

and the more ordinary effects of polymer/molecular weight/solvent/concentration/quench temperature/quench time

conditions, it may be possible to optimize microporous membrane and loam structure and performance.

TASK DESCRIPTION:

A microgravity environment will be simulated by use of isopycnic (iso-density) solutions of polystyrene in diethyl

malonate, which upon thermally induced phase separation do not exhibit any macroscopic layering effects on the

time frame of a week. Comparisons will be made to convention'd, nonisopycnic polystyrene solutions.

Early-stage spinodal decomposition effects will also be investigated by comparing the experimental temperature

dependence of pore size to predictions from the linearized Cahn-Hilliard theory for spinodal decomposition.

Measurements of the average pore size and pore-size distribution in membranes and foams produced by thermally

induced phase separation will be characterized by scanning electron microscopy and mercury, intrusion porosimetry.

Comparisons of the growth rate in pore size observed from the three-dimensional membranes will be made to m

situ measurements of phase separation and coarsening in polymer solutions by optical microscopy; the thin nature

(- 10 tam) of the solutions may yield two-dimensional coarsening effects.

TASK SIGNIFICANCE:

The effects of gravity in the production of microporous membranes and foams from phase separated F)lymer

solutions will be studied quantitatively for the first time. By accessing microgravity conditions, it will be possible

to study critically how the phase domain growth rate during coarsening compares to theories, including those related

to the Ostwald ripening mechanism and the hydrodynamic flow mechanism of coarsening. From a scientific

standpoint, by simulating microgravity conditions it will be possible to test for the first time the evolution of

coarsened microstructure in polymer solutions over five to six decades in phase separation ume and to determine

how gravity-driven flows affect this evolution. From a technological standpoint, the microgravity environment

using the isopycnic solution will allow determination of how space processing of microporous polymer membranes

and foams may result in materials unobtainable or obtainable only for limited polymer species (where isopycnic

solutions can be found) in a conventional terrestrial environment.

II--61 5
PROGRESS DURINGFY 1994:

The phase separation of isopycnic polystyrene-diethyl malonate solutions has been studied by investigating the

microstructure of polymer membranes. Polymer solutions underwent spinodal decomposition and coarsening via a

thermally induced phase separation procedure, and supercritical CO2 extraction was employed to remove solvent,

resulting in microporous membranes. At relatively short coarsening times, the coarsening rate of the cell size can

be expressed as a power law in time with the exponent increasing with increasing quench depth; for deep quenches,

the growth rate has an exponent of 1/3 in agreement with the classic theories for coarsening by Ostwald ripening or

coalescence. At longer coarsening times, there was a crossover to a much faster growth rate, yielding an exponent

of 1.0 independent of phase separation temperature, consistent with expectations for the hydrodynamic flow

mechanism of coarsening suggested by Siggia. This is the l_st experimental cont-u-mation of the evolution of the

coarsening mechanism from one mechanism with a growth rate consistent with Ostwald ripening or coalescence to a

second mechanism with a faster growth rate. Comparisons were also made to coarsening observed in

nonisopycnic/low-viscosity polystyrene-cyclohexane systems where strong gravitational effects dominate the phase

separation process at relatively short times and crossover effects cannot be observed.

The elfecLs of coarsening on microstructure formation in highly viscous polystyrene-cyclohexanol solutions and

membranes made from them were "also studied by scanning electron microscopy and mercury intrusion porostmetry.

Using thermally induced phase separation and a _eeze-drying technique, it was demonstrated that the polymer

membrane microstructure can be tmlored by controlling the quench route and coarsening time. For systems

undergoing phase separation by spinodal decomposition, resulting in a well-interconnected, microporous structure

with nearly uniform pore sizes, it was found that extending the phase separation tune prior to freezing and solvent

removal can result in a significant increase in pore or cell size which is highly dependent on both quench depth and

coarsening time. The coarsening rate of the cell size can be expressed as a power law in time. For relatively deep

quenches, the initial growth-rate exponent has a value of 1/3 in agreement with classical theories for coarsening by

Ostwald ripening or coalescence, while for shallow quenches smaller exponents were observed, in agreement with

studies involving isopycnic polystyrene-diethyl malonate systems. At longer coarsening times, a crossover to a

much faster growth rate was observed yielding an exponent of 1.0, consistent with the expectations for the

hydrodynamic flow mechanism of coarsening. This indicates that highly viscous, but nonisopycnic polymer

solutions can, under certain circumstances, exhibit coarsening phenomena similar to that observed in an isopycnic,

low viscosity polymer solution. Novel, complex microporous membrane structures with pore sizes of two

characteristic length scales were also produced in this system using a two-step temperature jump process.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0

MS Students: 0

PhD Students: 1

TASK INITIATION: 6194 EXPIRATION: 6196

PROJECT IDENTIFICATION: 962-21-08-23

NASA CONTRACT NO.:NAGS-1061

RESPONSIBLECENTER: MSFC

i i ai l i i I le Il I l I I l l I I I l I lI I II I I i l i i I l Ii iI I I l i I l I I Ie II, I I I l I l l I I ml l l I I I l I i l I, i lI l i i l l l I I I I l I I I l¢l l I i I eI l l I lI I lI I I l l I l I I I I i lI l l l I I l I l I I lI l I l I l I t l I I I I I I Il l Il l I I I I l ei I I l I l l l i i i i l I l I I i i i i i iI i l l I l I i I I i Ii i i i i i I l i I i i i i i i i l l I I l i I II I I I I I I I I I lI l l I I, l i I I lI I

11-616
Fundamentals of Mold-Free Casting Experimental and Computational Studies

PRINCIPALINVESTIGATOR:Prof. Gr6tar Tryggvason University of Michigan

CO-INVESTIGATORS:

S.L. Ceccio

Dr. D. Jacqmin

University of Michigan

NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

• Provide the scientific knowledge necessary, to operate a net-shape drop and spray casting facility by a computer

designed and optimized process. In addition to its importance for earth based manufacturing, such knowledge will

'allow the operation of a space based facilities by computer programs developed on earth.

• Develop a detailed understanding of the fluid mechanics, heat transfer, and solidification of drops splattmg on a

solid surface or a layer of other drops, that can be used to predict the microstructure of solids formed by such

depositions.

TASK DESCRIPTION:

The project has both an experimental and a computational part. The experiment will consist of a facility that will

'allow drops of controlled size and velocity to be deposited on a flat substrata where they solidify. The numerical

part will build on techniques developed under previous NASA support for accurate simulations of drop motion. By

a careful comparison of the numerical and the experimental results, we expect to be able to identify the key physical

aspects of the process that must be included in the numerical model so that it yields accurate results, yet is

sufficiently fast to be of practical use. To scale-up the drops to allow more detailed observations of the process, we

expect to eventually conduct the experiments in a low gravity environment where the drops can be made larger and

the velocities smaller, while keeping the essential balance of physical effects the same as for the small drops that

will be used in the actual production of artifacts.

TASK SIGNIFICANCE:

Moldfree casting by precision controlled deposition of drops of molten metal is an emerging manufacturing process

with considerable promise for rapid prototyping and the production of high quality, custom artifacts. A detailed

understanding of the process, and the ability to predict the effect of the controlling parameters, is essential if the

technique is to reach its lull potential.

PROGRESSDURING FY 1994:

The project has bo,! ,_: e.,,pcrtmental and a computational part. The experiment will consist of a facility that will

allow drops of controlled size and velocity to be deposited on a fiat substrata where they solidify. Design of this

facility is underway. The numerical part is building on techniques developed under previous NASA support for

accurate simulations of drop motion. A computer program has been developed that models solidification together

with two-phase (liquid-vapor) surface-tension induced flow. It is currently being tested by carrying out simulations

of the solidi/\cation of a liquid with a tree surface in a container.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 7/94 EXPIRATION: 7/96

BS Students: 0 PROJECT IDENTIFICATION: 962-25-05-28

MS Students: 0 RESPONSIBLE CENTER: LeRC

PhD Students: 1

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I1--61 7
[I. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

o lH i i o|t i o i i o Dloo I itl iio i|on! ell iltll iio i n l i i in i o llo i IHI u i o nl o ol tol o tltt i H i it i iol I Ila|l i o nl It lot IH I I ol i|1 i! I I to I o tilt n I t tR0t 10t I It I I H I tO IH II I I I 011 o l I t lI I 01 Ol I Ol I t tOOOlOtiOalU I. iit I ion ion i U lIt ii t nl u tit I I llu u I o tonlaollolu I I oo I ol I o

Electromagnectic Field Effects in Semiconductor Crystal Growth

PRINCIPAL INVESTIGATOR: Dr. Martin P. Volz NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

K. Mazuruk

D.A. Watring

G.S. Dulikravich

Hughes STX

NASA Marshall Space Flight Center (MSFC)

Pennsylvania State University

TASK OBJECTIVE"

The objectives of this investigation are the following:

1. To investigate the effects that combined electric and magnetic fields have on gravitationally-driven fluid flow

processes during the bulk growth of selected semiconductor alloys.

2. To examine the criteria tbr the onset of thermal instability as a function of electric, magnetic, and gravitational

field strength in electrically conducting liquids via theoretical analysis, computer calculations, and laboratory

experiments.

3. To assess the possibility of using externally applied magnetic and electric fields to influence fluid motion in the

melt, the rate of solid phase accrual, and the shape of the solid/liquid interface during solidification experiments both

on earth and in a low gravity environment.

TASK DESCRIPTION;

A series of specific tasks are planned to achieve the proposed objectives. A model growth cell will be developed

which will allow for the passage of electric current through the melt simultaneous with the application of a

magnetic field, ln-situ temperature measurements will be made using gallium as a model material. Both

zone-melting and vertical Brid_nnan thermal profiles will be applied and the onset of thermal fluctuations will be

measured as a function of electric and magnetic field strength. Crystal growth experiments will then be made on

GalnSb and CdTe under various electromagnetohydrodynamic conditions. Computer modelling of the above systems

will be accomplished by using a three-dimensional mathematical model which takes into account both

magnetohydrodynamic and electrohydrodynamic phenomena. The model predictions will be compared with the

experimental results from the model growth cell.

TASK SIGNIFICANCE:

Electromagnetic fields can interact with electrically conducting melts and substantially affect their fluid flow

processes. Indeed, the intriguing possibility exists of using combined electric and magnetic fields to control fluid

flow in the melt during the directional solidification of semiconductor alloys. The significance of this study is to

gain a basic understanding of the possible interactions that combined electric and magnetic fields can have on fluid

flow processes during semiconductor crystal growth.

PROGRESSDURING FY 1994:

During the tirst three months of this investigation, construction was begun on a model growth cell. In addition, a

cooperative agreement was established between MSFC and Pennsylvania State University so that the modelling

effort can begin soon.

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11418
II. MSADProgramTasks-- Ground-basedResearch Discipline:MaterialsScience

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 9/94 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 962-21-08-24

NASA CONTRACT NO,: In-house

RESPONSIBLECENTER: MSFC

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il--619
II. MSADProgramTasksm Ground-based Research Discipline: Materials Science

H.II00_HllU0|01.1aG .II.10|t.|.II0110|ItlI|00|0110011Hn|0t .llollunlolaollaolnolu_|lo|lo|lolololloll_ll_lHlulHl|ollo-*llHl|H HI J ol|o|loH o lnJol.lnollollullHa|H oil oH 01HH 011|01||I00 H alI.IHI011UlIn|II|UlHIIll0H0|I0110

Coarsening in Solid-Liquid Mixtures

PRINCIPALINVESTIGATOR:ProL Peter W. Voorhees Northwestern University

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this project is to plan and perform a microgravity experiment on Ostwald ripening in solid-liquid

mixtures. This experiment will serve two primary purposes:

1. It will allow experiments to be pertormed which can be directly compared to heretolore untested theories for

coarsening in systems with low volume fractions of solid.

2. It will eliminate conclusively convection of the liquid matrix and small-scale particle motion within the skeletal

structure as possible sources for the disagreement observed between theory and experiment in the high volume

traction experiments.

TASK DESCRIPTION;

Previous NASA sponsored work clearly showed that solid-liquid mixtures consisting of Sn-rich particles in a Pb-Sn

eutectic liquid are ideal, and perhaps unique, systems in which to explore the dynamics of the Ostwald ripening

process. The high coarsening rate in these systems permit accurate kinetic data to be obtained, and the

thermophysical parameters necessary to make a comparison between theory and experiment are known. However,

in a terrestrial environment experiments can be pertormed only at the relatively high volume fractions of solid

where the presence of a solid skeletal structure prevents large-scale particle sedimentation. In these high volume

fraction experiments, a comparison between theory and experiment shows that the solid-liquid mixtures are

coarsening faster than predicted by an approximate theory for purely diffusional controlled Ostwald ripening. Thus,

the we are in the process of formulating a microgravity experiment. This experiment will serve two primary

purposes: it will allow experiments to be performed which can be directly compared to heretolbre untested theories

for coarsening in systems with low volume tractions of solid, and it will eliminate conclusively convection of the

liquid matrix and small-scale particle motion within the skeletal structure as possible sources for the disagreement

observed between theory and experiment in the high volume traction experiments.

TASK SIGNIFICANCE;

The spaceflight experiment will produce data which, for the ftrst time, can be compared directly to theory with no

adjustable parameters. This data will address the long standing controversy over the dependence of the coarsening

rate of a two-phase system of the volume traction on coarsening phase.

The results from the spaceflight experiment will further our understanding of the processes responsible for

microstructural development in a broad range of commercially important materials ranging from turbine blade alloys

to liquid phase sintered materials.

PROGRESSDURINGFY 1994:

During this past year we began setting the science requirements for a spaceflight experiment. Specifically, we have

examined the effects of g-jitter on the motion of a solid particle in a fluid, examined the effects of long-term storage

at elevated temperatures on the microstructure of previously coarsened Pb-Sn samples, and prepared the preliminary

science requirements document. Our theoretical investigation on the effects of g-jitter showed that g-jitter of the

relatively small amplitude and frequencies characteristic of routine crew movement on the space shuttle can induce

significant motion of Pb solid particles in a Pb-Sn eutectic liquid. Thus, we were able to determine that the

!1-620
IL MSADProgramTasks-- Ground-based Research Discipline: Materials Science

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spaceflight experiment must be performed during crew sleep periods. In addition, the long-tune annealing studies

showed lhat either t_)llowing or preceding the spaceflight experiment the samples cannot be exposed to temperatures

m excess of 30C. Finally, we have been interacting with engineers at NASA Lewis in the design of a furnace

which can be used in a microgravity coarsening experiment. We have "also continued our ground-based research. We

have examined experimentally the dymtmics of transient coarsening in solid-liquid systems, and are in the process of

developing an automated serial sectioning machine. The transient coarsening experiments showed clearly that both

the spatial arrangement of the panicles and the form of the initial particle size distribution can have a major effect

on the dynamics of the coarsening process at short times. However, as coarsening of the microstructure proceeds,

the system approaches the classical steady-state coarsening process. The automated serial sectioning machine will be

used to an',dyze the results of the spaceflight experiment as well as to explore the three-dimension;d morphology of

the solid-liquid mixtures produced both on the ground and in space.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: ]/92 EXPIRATION: 10t95

PROJECT IDENTIFICATION: 963-25-05-10

NASA CONTRACT NO.:NAG3-I417

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

.Journals

Chen. M. and Vo_rhees. P.W. The dynamics of transient ostwald ripening. J. Model and Sim. in Mat. Sci., 1, 591 (1993).

Voorhees. P.W. Coarsening. Encyclopedia of Advanced Materials. Pergamon Press, (1994).

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I1-621
II. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

a lllllaolllolllll "nal|v_o_"_Ill"_oI_Illio_"_on_|n_n_|o_H_"_"_|o_no_"I_o_o|n_n_Io_H_11_H_"_Io_H_u_HnH_;an_H_H_o_nno_111_no_In_H_H_on_oH o JlolJolaoHolo|ll!loolno||looloolaollolleHeloo|oom|llolonloHollonn|l

Containerless Liquid Phase Processing of Ceramic Materials

PRINCIPALINVESTIGATOR:Dr. Richard J. Weber Containerless Research, Inc.

CO-INVESTIGATORS:

P.C. Nordine Containerless Research, Inc.

TASK OBJECTIVE:

This research uses the control of chemistry and nucleation achieved by containerless liquid-phase processing to study

non-equilibrium phase formation and crystal growth. The work is intended to advance the basic understanding of the

high temperature chemistry of hard, refractory oxide and boride ceramics. Borides are of fundamental interest; they

are a unique class of compounds which form highly covalent, complex crystalline structures.

Ground-based containerless experiments will enable non-equilibrium phase formation phenomena to be identified.

This will allow candidate materials for more detailed investigation to be selected. Subsequent low gravity

experiments will provide the high degree of control over molten specimens required for detailed studies and analyses

of the liquids as well a_scrystal growth kinetics and solid-liquid phase relationships.

TASK DESCRIPTION:

High temperature liquid-phase processing is achieved by aero- acoustic and aerodynamic levitation in combination

with continuous wave CO_ laser beam heating. Levitated materials are viewed by optical pyrometers and video

cameras. Materials are being examined by optical and scanning electron microscopy, X-ray diffraction, nuclear

magnetic resonance, Raman spectroscopy, and laser fluorescence measurements.

The effects of melt chemistry, temperature and process variables, including gravity-driven convection on

solidification kinetics, metastable phase formation, and epitaxial growth onto isostructural seed crystals from

undercooled melts is being investigated.

TASK SIGNIFICANCE;

The work provides insights into subtle chemical and transport effects on the solidification of complex oxide and

boride melts. The investigation explores the limits of ground-based methods and identifies systems which require

the additional control of transport which may be possible in low gravity.

PROGRESSDURINGFY 1994:

The investigations have so tar concentrated on work with oxide- based melts. Materials selected were calcia-gallia

(C-G) mixtures (in collaboration with Professor D.E. Day and Dr. C.S. Ray from University of Missouri-Rolla),

"aluminum oxide, yttrium-barium-copper oxide ceramic superconductor materials, and rare-earth borides.

Most of the results have been published or presented:

1. Measured effects of solid contact on C-G glass formation characteristics

2. Investigated aluminum oxide structure-properties as a function of p(Oz)

3. Established control of YBaCuO phase relationships via oxygen pressure

4. Conducted containerless melting of boride materials

5. Conducted collaborative investigations with scientists at Argonne National Laboratory, Jet Propulsion

Laboratory, University of Wisconsin, Madison, and Vanderbilt University.

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II-622
lI. MSAD Program Tasks -- Ground-based Research Discipline: Materials Science

H_i_"_i_"_|_|_t_i_ÈI_!_u_*_"_i_"_*"1|_lm_"1H_|_i|i_s*i"H*IHt .O,,,,*|Ja*t|i.*10*ilsIH*|l|i,IIll*ll_|l,*i,ltl**n H*lU*|l|Hl¢*l|,*01*e011ii |li,|i,*imIHlinllO|i*II¢, HHIHI,II,HI|

The present work has achieved a high degree of control of melt chemistry, nucleation, and the gas environment in

ground-based contmnerless experiment,s on high temperature melts. Examples where increased control is needed are

the following:

1. Glass formation - Stirring enhanced crystallization rates by transporting nuclei through melt.

2. Aluminum oxide - temperature gradients limited the ability to process and investigate liquids in uniform

thermodynamic states.

3. YBaCuO material - segregation of Y,.O3 particles limited control of the product microstructure.

Melt properties depend on composition and temperature and the composition itself depends also on temperature

under fixed ambient conditions. Microgravity provides access to more uniform melt temperatures and compositions

as well as control of fluid motion needed tbr transport property measurements. Measurements of melt properties are

a key to understanding solidification behavior in ceramic systems, large changes in viscosity result from the

response of liquid structure to temperature and composition changes. Experiments on the NASA KC-135 are

planned in a collaboration with a Canadian research group.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 5/92 EXPIRATION: 5/95

PROJECT IDENTIFICATION: 963-26-07-03

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Olive, J.R., W.H. Hofmeister. R.J. Bayuzick. G. Carro, J.P. McHugh, R.H. Hopkins. M. Vlasse, JK.R. Weber, P.C.

Nordine and M. McElfresh. Formation of tetragonal YB_Cu_Ovs from and undercooled melt. J. Mat. Res., 9, 1-3 (1994).

Weber, J.K.R. and P.C, Nordine. Containerless liquid-phase processing at high temperatures. Microgravity Science and

Technology, (In press).

Weber, JK.R., C.D. Anderson, S. Krishnan and P.C. Nordine. Structure of aluminum oxide formed from undercooled melts.

.l. Am. Ceram. Soc.. (In press).

Weber. J.K.R., D.R. Merkley. C.D. Anderson, P.C. Nordine ,C.S. Ray and D.E. Day. Enhancement of calcia-gallia glass

formation by containerless processing. J. Am. Ceram. Soc.. 76, 2139-41 (1993).

Weber, J.KR., D.S. Hampton. D.R. Merkley, C.A. Rey, M.M. Zatarski and P.C. Nordine. Aero-acoustic levitation - A

method for containerless liquid phase processing at high temperatures. Rev. Sci. Instrum., 65, 1-I0 (1994).

Weber, JK.R., P.C. Nordine, K.C. Goretta, and R.B. Poeppel. Effects of oxygen pressure on the structure of Y-Ba-Cu-O

Materials formed by containlerless melting and solidification. J. Mat. Res., 9, 1657-60 (1994).

Proceedings

Weber, J.K.R., W.P. Zima, P.C. Nordine, K.C. Goretta, and R.B. Poeppel. "Containerless processing of ceramic

superconductors." Proceedings of TMS: Containerless Processing Techniques and Applications, Warrendale, PA, 1993.

II-623
BSO/BTO Identification of Gravity Related Effects on Crystal Growth, Segregation, and Defect

Formation

PRINCIPALINVESTIGATOR:Prof, August F. Witt Massachusetts Institute of Technology (MIT)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

Knowledge gained from space experiments and the related ground-based program is expected to advance the science

base for crystal growth of oxides and thus to narrow the still existing gap between theory and experiment. More

specifically, the proposed program provides an approach to the deconvolution of the effects of largely uncontrolled,

complex processing variables on crystal growth and segregation, leading to the identification of growth conditions

by which device specific property requirements in oxides can be approached. Such growth conditions are expected to

be realizable in a modified Bridgman growth geometry, the subject of development in the ground-based support

program.

TASK DESCRIPTION:

The on-going research program on growth and characterization of BSO places locus on a class of materials (optical

and opto-electronic) with theoretical properties that are outstanding, but which have so far failed to reach their

potential primarily because of our inability to adequately control during growth their stoichiometry, incorporation

of functional minority constituents, crystal defect formation and confinement related contamination. Theoretical

considerations indicate that the majority of existing growth deficiencies, which are responsible for our inability to

produce viable device structures, are directly or indirectly related to gravitational effects. Thus it appears that an

assessment of the true potential of selenites, which exhibit outstanding piezoelectric properties and exceptionally

light optical rotative activity in device application, can at this time best be made on material obtained from

controlled growth experiments in a reduced gravity environment. Under such conditions convective interference,

otherwise unavoidable, is projected to be substantially suppres_d and defect structures resulting during growth are

expected to approach equilibrium values. Magnetic melt stabilization, tound effective in growth of semiconductors,

is ineffective in oxide systems.

TASK SIGNIFICANCE:

The research to date has focused on (a) the development of BSO single crystal growth capability by the Czochralski

technique, (b) the characterization of growth and defect formation in BSO, and (c) the development of a

Bridgman-type growth configuration for BSO that permits enhanced heat transfer control under quantifiable thermal

boundary conditions and which is functionally compatible with NASA -generated existing hardware. The

establishment of quantifiable growth conditions and the in situ growth characterization capability by means of

current induced interface demarcation are considered e_ential in efforts directed at assessing the potential of reduced

gravity environment tbr crystal growth research and development since the customary empirical approach is

considered prohibitive in space experimentation. The approach taken is in addition also considered a key element in

efforts to establish advanced crystal growth capabilities on earth, a prerequisite for the meaningful assessment of the

potential of selenites in device applications.

PROGRESSDURINGFY 1994:

Crystal Growth of BSO

A heat pipe-based Czochralski system, providing tbr a controlled ambient atmosphere and current induced growth

interface demarcation, has been established and used extensively to grow material from which growth and

segregation effects in conventional operation are being determined.

II--624
Inviewof extensive experience in optical characterization gained from NASA-sponsored research of III-V and II-VI

compound semiconductors, existing facilities for optical transmission microscopy and related computational image

processing and analysis were modified to permit the characterization of oxides.

To determine the basic growth features of BSO, Ca-doped as well as undoped crystals using charges ranging from

50-70g were grown and analyzed. It was found that (1) rotational striations are absent in crystals grown with the

heat pipe based system; (2) non-rotation'at striations, highly periodic in nature and exhibiting two distinctly different

frequencies, are present in both the core and off-core regions; (3) the frequency of striation formation appears to be a

weak function of the aspect ratio of the charge, independent of the rate of seed rotation and not noticeably dependent

on the rate of crystal pulling; (4) the primary crystal deficiencies are gaseous inclusions; their appearance is a

function of both the rate of crystal rotation and the rate of crystal pulling; (5) generation of dislocations is lound to

be predominantly related to inclusion of "gas bubbles"; (6) dislocations have been made "visible" through decoration

by annealing in a reducing atmosphere; and (7) current induced interface demarcation has been successful - its

formation can be attributed to Joule heating rather than a Peltier effect.

Desitm of Brid_man Facility

A heat pipe based Bridgman facility has been designed and constructed. The system is equipped for interface

demarcation and will provide growth rate as well as thermal gradient stabilization. It is currently being tested for

performance characteristics using a "graphite charge" and will subsequently be used to establish growth conditions

for BSO in vertical configuration.

STUDENTS FUNDEDUNDER RESEARCH:

BS Students: 0 BS Degrees: 0

MS Students: 0 MS Degrees: 0

PhD Students: 2 PhD Degrees: 1

TASK INITIATION: 1/93 EXPIRATION: 1/96

PROJECT IDENTIFICATION: 962-21-08-19

NASA CONTRACT NO.: NAG8-949

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Lin, C., and Witt, A.F. Decoration of dislocations in Bil:SiO:0 (BSO) crystals by annealing in a reducing atmosphere. J.

Cryst. Growth. vol. 140, 444-446 (1994).

Proceedings

Witt, A.F. "Science transfer to technology: a necessity for realization of property control in semiconductors."

Proceedings of the International Symposium on Light Metals, The Metallurgical Society of CIM, Quebec City, Canada,

August, 1994.

Presentations

Witt, A.F. "BSO/BTO identification of gravity related effects on crystal growth, segregation and defect formation." NASA

Microgravity Materials Science Conference, Huntsville, AL, May 24-25, 1994.

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I1--625
II. MSADProgramTasks-- Advanced Technology Development

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Microwave Furnace Development for Microgravity Materials Processing

PRINCIPALINVESTIGATOR:Dr. Martin B. Barmatz Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this Advanced Technology Development (ATD) proposal is to build a highly efficient, cold-wall,

direct-heating microwave furnace that will permit fast heatmg of microwave-absorbing materials and quick cooling

of these materials when the microwaves are removed. The task objectives will include 1) development of advanced

energy saving methods for (a) continuous tracking of the cavity resonant mode during processing, (b) continuous

matching of source and cavity tmpedance during processing, 2) design, fabrication and evaluation of various cavity

geometries and excitation techniques, and 3) modeling of the microwave heating process for various sample shapes

and sizes.

TASK DESCRIPTION:

in the future, many materials processing studies in space will require specialized furnaces, particularly at high

temperatures. Requirements/or these furnaces include fast, controlled sample heating, high precision sample

temperature control, and last, controlled sample cooling. Furthermore, there are constraints that a microgravity

furnace should meet; i.e., they should be small, light weight, and very energy efficient. Properly designed

microwave furnaces can deliver most of the generated energy directly to the material being processed, thus leading to

improved energy efficiency. The design requirements for energy efficiency include critical coupling of microwave

energy from source to cavity, high electrically conducting cavity walls compared to sample conductivity, and

continuous tracking of the microwave resonance during processing. Furthermore, microwaves are able to directly

heat the interior of the materials, which differs from conventional heating methods, where only the sample surface

is directly heated. In some cases, this microwave volumetric heating ability can lead to more uniform processing,

while in other cases it may lead to an internal temperature profile with the highest temperature in the center of the

material. The furnace designs developed during this ATD task will allow unique microwave heating properties as

well as precision sample temperature control capabilities to be applied to microgravity processing. By the proper

choice of sample shapes, such as spherical or cylindrical, one can also theoretically predict the unique heating

behavior of the sample interior during processing.

TASK SIGNIFICANCE:

The unique microwave volumetric heating capabilities will permit new and novel scientific studies to be performed

in microgravity. At this time, scientific and industrial communities are re-visiting the use of microwaves as a

means to process materials on the ground, particularly at high temperatures. Many new materials processing

techniques using the unique capabilities of microwaves are now being evaluated and the technology associated with

this ATD should play an important dual-use role in developing improved commercial products.

PROGRESSDURINGFY 1994:

During the last year, we have (a) developed a new vibration technique for tracking the microwave mode resonance in

a 1 Kw magnetron facility using a motor plunger, (b) extended the above vibration technique to track the impedance

match between the microwave source and processing cavity in a 1 Kw magnetron facility using a motor controlled

stub tuner, and (c) developed a microwave heating model tor determining the steady state temperature profile in a

cylindrical sample in a cylindrical cavity.

11-626
STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/91 EXPIRATION: 9/94

PROJECT IDENTIFICATION: 92-1

RESPONSIBLE CENTER: JPL

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

McDonough, C., Barmatz, M., and Jackson, H.W. Application of Boltzmann-Ehrenfest principle to containerless

microwave processing in microgravity. Ceramic Transactions, 36. 581 (1993).

NASA Tech Briefs

Jackson, H.W.. Barmatz, M., Watkins. J.L.

no.3, item 80. 123 (March 1994).

Heating and positioning in a microwave cavity. NASA Tech Brief, vol. 18,

Proceedings

[ny, O. and M. Barmatz. "Decay method for measuring complex dielectric constants during microwave processing." MRS

Spring Symposium Proceedings, 1994.

Jackson. H.W., Barmatz, M.. and Wagner, P. "Microwave pm, ver absorption profile in a cylindrical sample contained in

resonant cylindrical cavity." IvlRS Spring Symposium Proceedings, 1994.

I I i I I II Jil J I oIll oII * II I oI aI Is oI i I IoI I l oI I I Ill iI i ii i i i l I l i i i i I I ii ii I I i I i ill i i iai i i i i I )i I i i ii i i PI i Ii iI lI I l l I I I I l I i l I Il i I I I eI I i eI li I ai i i i i I l l I i eiii l Jl i ii i oi i I ii i I i i III I Ill II I i i I I l I i i i i ai I i i I l Iei I oI I i ili i Ii ii l i i ill il I i i II II I Ill I I I I I II I I oI I I I I I I I Ii i

I1-..627
Stereo hnaging Velocimetry

PRINCIPAL INVESTIGATOR:Dr. Mark Bethea NASA Lewis Research Center 0_.,eRC)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objectives of this project are to develop a stereo imaging velocimeter that will:

1. Measure quantitatively and qualitatively velocities up to 10.0 crrdsec with an accuracy of 2.0% of full-field for

150-micron seed particles in a 2.0-inch field of view.

2. Have streamlined data processing which processes 100 time steps of consecutive stereo images to obtain 3D

velocity fields in less than ten minutes.

3. Be able to track at least 100 particle pairs per frame.

4. Require minimal apriori assumptions about the flow.

5. Initiate tracking and matching out automatically.

TASK DESCRIPTION:

The approach to successful implementation is to develop robust and efficient 3D camera calibration, edge

t'mding/centroid determination, overlap decomposition, particle tracking, and stereo matching algorithms that will

be used in the Stereo Imaging Velocimetry system. These five tasks are the basis for the velocimeter and will

determine its l-real processing speed and accuracy. We will then test the prototype for accuracy on particles with

known trajectories. A user interface for both the front-end and post-processing will be created. The velocimeter

will be tested on real fluids experiments. This testbed experiment will be done with a water tunnel experiment that

is currently under development. Using the water tunnel experiment, we can set the flow rate and compare the

results with the SIV system results.

TASK SIGNIFICANCE:

Stereo Imaging Velocimetry will permit the collection of quantitative and qualitative, three-dimensional flow data

from any optically transparent fluid which can be seeded with tracer particles. This includes such diverse

experiments as the study of multiphase flows, bubble nucleation and migration, pool combustion, non-contact

measurements, and crystal growth -- all of which are part of NASA's Microgravity science program.

PROGRESSDURINGFY 1994:

A neural network approach to particle tracking has been invented, coded, and tested. The results show a substantial

improvement over our existing particle tracking scheme. This work is significant in that we use a globally

optimum neural network instead of a locally optimum one. This increases our particle tracking yield by as much as

10%.

A 3D camera calibration technique has been developed and tested for the SIV system. We are now able to take two

2D calibration (orthogonal views) and extract 3D information from then to produce a robust 3D camera calibration

routine capable of calibrating our fluid volume to within 0.17% f full-field.

ili I I I I I t i i iI t i I Iil I I i I l I i I Il I I i i i I I I i I it I I i i I I I I I i i ii ii i I li I l I I i i i i I I iI i i I I I i I I i i i i il I lI I I i i I I i i i I it lI I i I i i i i l i I i iI i I I i I I I I l I Ili i II I il I Ii I Il I II I I I i i I i i i I i i i ii i I i i I I li I I I I I I II i I I I I it i I l II l l I I i I I I I I I Ii I i I I I I l I i i ii i i i i i i Iil I ¢i i li I I i i ii I I I I I I I I I I i

11-628
The Neural Network iInplementation ol Ihe overl:lpping parliclcs reported in FY 93 has been combined with our

edge finding-centroid processing algorithm Io fomt one robusl ;.tl_t)rilhlll.

The 3D camera c',dibration technique, overlap decomposition with edge-centmid determination, along with pamcle

tracking and stereo matching are currently berne combined in _)nc SIV algorithm This will produce our SlY

software system package aJld accuracy and spceJ will bc analyzed.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/91 EXPIRATION: 9/95

BS Students: 1 BS Degrees: (I PROJECT IDENTIFICATION: 963-70-012-00

MS Students: 1 MS Degrees: 3 RESPONSIBLE CENTER: LeRC

PhD Students: 2 PhD Degrees: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Kent, J.C., Trigui, N., Choi, W.C., Guczennec. Y. and Br¢,dkey, R.S. "Ph_m)grammetric Calibration for improved

tree-dimensional particle velocimetry I3 D PTVI." SPIE lIllcrnatlcJnal Symposium on Optics. Imaging, and

Instrumentation. San Diego, CA, July It I6. I%':;

Presentations

Meyer. MB. and Bethea. M.D "A full field, 3 1) vel_)__imctcr I(:r NASA',,, Microgravity Science Program." Presented at the

30th Aerospace Sciences Meeting & Exhibit, Reno. NV, January 6-9, 1992.

Meyer, M.B., Bethea, M.D.. Guezennec, Y.G.. and Choi, W.C. "Stereo imaging velocimetry: A new option for

microgravity experiments." Presented at the ASME 1993 Winter Annual Meeting, New Orleans, LA, November

28-December 3, 1993.

Miller, B. and Merat. F. "A neural network architecture I'.r gcnerahzcd category perception." Neural Network Conference,

June, 1993.

Miller, B.B., Meyer, M.B., and Bethea, M.I). "Stereo imaging vch_cimetry for microgravity applications." Presented at

the ASME 1993 Winter Annual Meeting, New ()rleans. I,A, November 28 l)ecember 3. 1993.

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11--629
II. MSAD Program Tasks J Advanced Technology Development

,t f, i i i *, I, ¢ III | i i i t,, ii ¢,,, ! i J,. s ¢ t,, t, i i i, i q _ i i i i t, ¢ I na | I ¢ n i ¢ t, i | iii i I ¢ i i i t,, i,,, g I I,, i,, | I| i, ¢Ii, i I I | t !, | i | I _I I I I H a ¢ | i mi, m011 !I | a | e !, ¢! t I I I | n !, I II | ! e I I ! I1¢ ¢ nI ¢ II e H s | I s I | | | 0| | i | |, I | I I | I| I I ¢ I I | I ! I ¢ J |u III ! Ill I11 e |a 0 III I| ¢ I! I Ill lie | Is I I | I | |I

Real-Thne X-Ray Microscopy for Solidification Processing

PRINCIPALINVESTIGATOR:Dr. Peter Curreri NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

W. Kaukler University of Alabama, Huntsville (UAH)

TASK OBJECTIVE:

The objective of this ATD consists in the development of an X-ray Transmission Microscope (XTM) for the in-situ

and real-time observation of interracial processes in metallic systems during freezing or solid-solid transformation.

The XTM should have the following capabilities:

1. provide a resolution for specimen features of 10-100 nun;

2. at solidification rates of 0.1 to 20 mm/sec;

3. temperatures up to 1100 C with temperature gradients up to 50 C/cm;

4. with contrast sensitivities sufficient to detect 2-5% difference in absorptance;

5. offer 1, 2 and 4 in exposure times of a few seconds; and

6. permit recording of stereo pairs/or depth information.

TASK DESCRIPTION:

The purpose of this ATD is the development of a high resolution x-ray either during freezing or solid-solid

transformations. The X-ray Transmission microscope to view, in-situ and in real time, inteffacial processes in

metallic systems Microscope (XTM) will operate in the hard x-ray range (10 to 100 keV) and achieve magnification

through projection.

TASK SIGNIFICANCE:

Physical processes which occur at, or near, interphase boundaries during solidification, or other phase

transformations, play a major role in the determination of many of the technologically important properties of

solids. To-date, interracial morphologies and particle-interface interactions in the respective metallic, optically

opaque systems have been deduced from post-process metallographic analyses of specimens. Thus, little

information is obtained about the detailed dynamics of the processes. These investigations have been considerably

augmented by real time observations of transparent materials; yet, since some of the interfacial and transport

properties of these materials differ greatly from those of metals and semiconductors the results are not necessarily

representative of these opaque systems.

PROGRESSDURINGFY 1994:

Procurement was achieved of a system which is of a capability of the order to that which we utilized for the proof of

concept studies. It basically consists of a Microfocus X-ray source, a X-ray image converter, and a CCD detector.

The sub-micron X-ray source is a relatively new technology and will not be improved upon during this ATD. The

detector / converter system of the unit is not optimized for real time analysis and will be improved as part of the

ATD el/oft.

A tit'st principles adsorption model approach was initiated for determining the use/ul contrast from a sample. Using

standard materials data and published X-ray spectra, the degree of absorption was calculated of the rays as they pass

through the inhomogeneous sample. Resolution limits established by the converter / camera combination were

introduced via Modulation Transfer Function, MTF, data for the X-ray image intensifier. This latter area of

modeling will require much more work to predict which conditions and apparatus will be optimum. The effort to

date provides use/ul information about the probability of observing important microstructural features and how

high a contrast the feature may have under ideal conditions.

11-630
lI. MSADProgramTasks-- Advanced Technology Development

o a o na o I n o | n o n i o | n o o i o i 11 o i i o i i g | i! o | i o o i i i BI o | i n o | I o i I i |i o ! o i i t i i o t I I oil o i no Iii i n o i i o H o o nl o i o H o n i ni n o ii o i o o io o n i o i n o i i o i iii i i o ii o i i o i i o o II o III I I o II OII OOI UO I II I I On I o o I I OII Ill I OI n a J I o Oa a o I a o I IOI I OI I OI I On I oo I I o II a i a a n I In I In I n o I I In I o o I a o I I o OI 0 OI

Several X-ray conversion technologies have been surveyed for applicability to this project. Due to the real-time

requirements, film is not suitable for use in this project except to record images of stationary specimens. Only

technologies that offer instant or real-time images will be considered.

Evaluation of new CCD X-ray Converter and camera technology has been perlormed. This technology uses

radiation hardened CCDs as a direct conversion, hard x-ray detector tor medical purposes. This competitive

technology may offer a superior means of seeing the features microstructural features of most scientific interest with

increasing resolution and potentially higher gray level sensitivity properly called dynamic range.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/94 EXPIRATION: 10/97

PROJECT IDENTIFICATION: 963-70-04

NASA CONTRACT NO.: In-hou_

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Presentations

Kaukler. W.F., Rosenberger, R.. and Curreri. P.A. "Specimen image optimization of the X-ray transmission microscope."

Eighth Annual Alabama Materials Research Conference. Tuscaloosa. AL. September 26. 1994.

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11-631
II. MSADProgramTasks-- Advanced Technology Development

Microgravity Combustion Diay, nosttcs

PRINCIPALINVESTIGATOR: Paul S. Greenbcrg NASA Lewis Research Center (LeRC)

CO-INVESTIGATORS:

Dr. D.W. Griffin

Dr. R.L. Vander Wal

Dr. K.J. Weiland

NASA Lewis Research Center (LeRC)

NYMA, Inc.

NASA Lewis Research Center (LeRC)

TASK OBJECTIVE:

Currently available diagnostic insuumentation for achieving these objectives has been extremely limited, consisting

primarily of conventional film-based imaging systems and intrusive temperature and velocity probes, such as

thermocouples and hot wire anemometers. This situation has _trisen primarily because of the unique and severe

operational constraints which are inherent in the conduct of reduced-gravity experimentation. It is the recognition of

this pressing need to provide diagnostic systems of greater sophistication that has motivated the existence of this

particular development program.

TASK DESCRIPTION:

For a variety of reasons, predominant emphasis has been placed on the deveh)pment of optical diagnostic

techniques. Principal among these is the relative fragility ol the physics and chemistry of reduced-gravity systems

relative to their 1-g counterparts. The action of buoyancy-induced convection is vigorous when compared with the

dominant mechanisms associated with reduced-gravity phem)mena, such as surface tension and thermal and

concena'ation driven diffusion processes. The essentially nouperturba_ive nature of optical measurement techniques

is therefore extremely appropriate in this context.

Optical measurement techniques are, in general, well-suited to the acquisition of multidimensional dam fields (e.g.,

two- and three-dimensional imaging). This is an Unportant consideration in the present state of understanding of

microgravity science, since a clearer understanding of basic phenomenology, including the verit]cation of

fundamental length and time scales and dominating physical mechanisms in still being developed.

TASK SIGNIFICANCE:

The success in achieving a significant scientific return from existing and proposed microgravity fluid physics and

combustion science experiments depends substmltially on the availability of diagnostic systems for the collection of

the required scientific data.

PROGRESSDURING FY 1994:

In the area of full-field infrared emission spectroscopy, calibration of fhe IR sensitive stanng array camera has been

conducted. This was accomplished through the use of a blackbody radiation source and several infrared bandpass

t-titers. An end-to-end calibration is required in this case because of the varying response of the detector array and the

transmission characteristics of the lens and bandpass filters. All of these elements exhibit behavior that is

wavelength dependent; the detector response may exhibit nonlinearities with respect to absolute intensity as well.

The response of the detector array has been observed to be nearly proportional to blackbody intensity when narrow

band filters are employed. As a first step in exploiting this calibration, images of radiating thin filament fibers

suspended in jet flames have been obtained. The resulting data will be compared to thermocouple measurements of

the hot gases above the flame that were obtained simultaneously.

A preliminary literature search was made investigating the inverse problem wherein infrared emission measurements

are inverted to provide temperatures and concentrations of selected species. The present search locused on references

comparing modelling efforts and experimental data for an experimentally tractable (soot-tree, relatively simple

chemistry, straightforward geometry) combustion system. Published infrared spectra of some laboratory Ilames,

such as a Bunsen-type natural gas flame, have also been found.

_I_I_I_*_t_eI__e*_I__I_Ie__*_I_*_*_i_1_*_t_e_*_I*_i_o__I_¢_1I_*_t

il-632
II. MSAD Program Tasks -- Advanced Technology Development

, a o, i o o n on I o n J o o n o o, u, i ao o t| o o o ! u o | i u i | ti o in i n a t u i, 11 o oo i o t a o i a o n o u, a| ma o i n o o a, I I o o io o o a o o I o o I o | i o ii o o ! o o I o o o I o I I oo I a o o a o o J I o I I o o I o o oi o ii o i a o o a o i s o o ti, i I * I a o a a o ¢ I o o mI o o n I u I o n a o o i no i a¢ i I o o i i, i u o o ! o o I n o | _ a o n n o o i g, i a _ ! a o o ii o iu u i ulu a o i a o o ao i a i, a s i a

Independent of this ATD, a Phase lI SBIR contract was signed with SSG. Inc. for the development and subsequent

delivery of an infrared tmaging spectrometer capable of supplying spatially and spectrally resolved images. Two

design reviews for the instrument were held to finalize design requirements and specifications. As part of this effort,

an estimate of the radiation levels expected from nucrogravity flames was required to assess the required instrument

sensitivity. No microgravity data was found to exist, so published data from measurements conducted in the

laboratory on laminar and turbulent gas jet flames was used. In addition, the DARTFIre Co-Investigator provided

information on her calculations of the radiation levels expected from burning PMMA in microgravity.

Efforts supporting two-dimensional species and temperature measurements were initiated with the completion of the

procurement process for the titanium:sapphire laser. The laser, built by Continuum, Inc., was installed into a new

laboratory room in the Space Experiments Laboratory. Through frequency doubling, tripling, and mixing of the

titanium:sapphire fundamental output, light in the blue and ultraviolet has been successfully generated. These lines

cover the wavelength regions of 431 nanometers and 308 nanometers, providing the ability to perform laser-induced

fluorescence measurements of the CH and OH radicals, respectively. This laser system is currently being

characterized as to its operational capabilities. Optics and other support equipment (burners, chamber, etc.) to

perform Rayleigh scattering, laser-induced fluorescence, and other optical diagnostics have been obtained and are

presently being assembled.

Characterization of this new device began by looking at water, which is optically active throughout the fundamental

wavelengths of the laser and allowed familiarization of the laser system without the worry of frequency conversion.

A photoacoustic cell and associated electronics were constructed. Excitation of various absorption bands of water at

room temperature can be detected, thus serving as a frequency marker to reference the laser tuning process.

Synchronization of the laser pulses, data collection systems, and wavelength tuning has also been implemented.

Next, the frequency doubling capabilities of the laser were characterized. Several millijoules of light could be

produced at 390 nm, which is in the range of one of the CH radical electronic transition. The laser was set up to

automatically scan the frequency conversion crystal angle as the wavelength is scanned. The scan rate for

auto-tracking was determined to be at least 0.1 nm/sec. The tuning range of the laser when optimized at a particular

wavelength is greater than 60 nm, although the auto-tracking alignment must be slightly realigned for good tracking

at roughly 20 nm intervals.

A Bunsen-type methane/air flame was set up and a point, laser-induced fluorescence signal of the CH radical present

in the inner cone of the flame was obtained with the use of a monochromator and photomultiplier tube detection

system. The peaks were assigned using published line positions. From the difference in the actual versus measured

wavelength of about 2.32 rim, a wavelength calibration of the laser can be made.

Exciplex thermometry experiments are being performed utilizing a small pulsed nitrogen laser operating at 337

nanometers. The objective is to utilize this method to measure the temperature of a vaporizing droplet, and extend

the technique to a burning droplet. Exciplex thermometry utilizes the ratio of fluorescent intensities of an excited

state monomer and exciplex compound (formed through the interaction of an excited state monomer and ground state

partner). By referencing this ratio of fluorescence intensities to calibration measurements in which the intensity

ratio is measured at known temperatures, the temperature can thus be determined. This technique has been applied

to measure the volume average temperature of a fiber suspended droplet in an inert atmosphere in response to

heating by a hot wire coil surrounding the droplet. The system in this case is hexadecane doped with PYPYP.

Application of exciplex thermometry to burning droplets remains a challenge as the fluorescence from the monomer

and exciplex are quenched at different rates in the presence of oxygen. Current efforts are aimed at addressing this

issue.

Point-wise and imaging velocity measurements are also in progress. Addressing the former, compact, solid -state

laser doppler velocimeter modules have been obtained on loan to supplement the module being completed under

contract. This module is implemented for coaxial backscatter measurements, utilizing common optics for

simultaneous transmission and detection. This simplifies the experimental geometry, and eliminates the

requirement for precise alignment of separate transmission and collection sample volumes. Acceptance tests of the

optics module were performed during September of 1993 at EG&G's facility in Montreal. The results of these tests

indicate that the unit performed as per specification. A comparative basis for the resulting performance was afforded

11-633
II. MSADProgramTasks-- Advanced Technology Development

by the availability of a pair of similar units presently in use in our laboratory. These units were loaned from the

David Taylor Institute of the Naval Research Laboratory. Both the EG&G and NRL units employ diode laser

sources operating at 780 nanometers, delivering approximately 15 milliwatts at the sample volume. Both units

'also employ DC coupled, avalanche photodiodes operating in the sub-geiger module (i.e. analog detection as

opposed to photon counting). For comparable optical power present at the sample volume, the EG&G module

',:d'fords an improved detection sensitivity by roughly a lactor of four. A two-told improvement is evident directly

from the indicated data, whereas the additional factor of two results from F# considerations; both modules employ a

collection aperture of 50 millimeters, but the EG&G module has a working distance which is 1.4 times as long.

Also visible in the data is the considerable improvement in the spatial definition at'forded by the EG&G module.

The radial profile of the sample volume is very close to the predicted value of 100 microns, and much more closely

resembles the l/e2 profile associated with the source. The NRL unit, in contrast, has inferior beam shaping optics,

resulting in a series of unwanted "wings" which contribute to the overall scattered signal.

Upon receipt of the EG&G optics module at LeRC these tests were repeated. Unfortunately, two anomalies in the

performance of the system were observed which were not seen previously. The first corresponds to a misalignment

between the transmitted and detected sample volumes. Data was collected to indicate the output of the avalanche

photodiode detector as a partially reflective target was translated along the optical axis. It is seen from the resulting

plot that the detection sensitivity peaks approximately 20 millimeters behind the sample volume as defined by the

transmitter. Because the detection optics operate at a conjugate ratio on the order of 10:1, this is indicative of a

misalignment of the detector by roughly two millimeters. This distance was later revealed to correspond to a shift

in the distance between the entrance window and sensor surface that had been altered in the final version of the

detector. This change had evidently not been indicated in the final configuration drawings, and hence had become

inadvertently misaligned in the final cleaning, purging, and sealing of the module which occurred prior to shipment.

The second anomaly relates to 50 KHz bleed-through from the detector high voltage power supply, and was traced to

a leaky by-pass capacitor. The module has subsequently been returned to EG&G, where these problems are

presently being corrected.

In the interim, the NRL units continue serve as a basis for further system development. A TSI-IFA 750 burst

spectral processor has been obtained on long-term loan from the Propulsion Systems Division here at the

Laboratory, and is presently being utilized lor assessing the perlormance of particle seeders suitable Ior reduced

gravity applications. Conventional seeders are predicated on fluidized beds or sedimentary reservoirs, both

configurations being inappropriate for reduced gravity applications. As an initial step in establishing familiarity

with this combination of optics module and processor, velocity profiles were acquired from a non-reacting jet seeded

with a water vapor nebulizer. Turbulence intensities in excess of 30% were calculated from 1K sample pdfs, and

have the expected spatial profile associated with laminar-to-turbulent transitions of this type. Also obtained is the

data rate associated with each sample point. These rates peak at roughly 9.6K velocity estimates per second, falling

short of the capacity of the processor by more than 10:1. This behavior is attributed to the polydispersity of the

seeder; previous measurements indicate that more than half of the droplets produced are well below 0.1 micron in

diameter, yielding visibilities which are below the measurement threshold of the combined instrument. When

operating closer to the throughput capacity of the processor (120K estimates/see), turbulence estimates derived from

similar pdfs should be obtainable in 10 - 20 milliseconds/point. This increase in arrival rate (i.e. validated and

processed) of resolvable particles will be sought from subsequent seeder designs, which are based on the entrainment

of near monodisperse particles in a fully turbulent enclosure. The throughput that is ultimately achieved from such

a system will provide an upper bound/'or the rate at which multi-point spatial scans may be pertormed.

In the area of Particle Image Velocimetry, a specially configured, pulsed Nd:YAG laser was received. This laser was

designed to emit a 4 pulse burst every second; shots in the burst are repeated at a rate of 1KHz. It also can produce

single pulses with a 30Hz repetition rate, although the energy produced is much less. The output is frequency

doubled to 532 nanometers via an internal doubling crystal. This laser uses a recently developed folded-resonator

configuration, resulting in an extremely compact optics package. Although some "tweaking" of this system was

required by the manufacturer, subsequent acceptance testing of this unit has validated that the specified performance

has indeed been achieved. In addition to the rugged, compact packaging of the optical head, this laser system is

configured so as to be compatible with operation in either the NASA Learjet or KC-135 aircraft.

11--634
Followingreceiptofthelaser,acvchmicinseruontluidizedbedseedchamber w,_k,_ designedandfabricated. This

seederis intended for use with g_ lets which are identical to,those in use by investigators currently funded under the

MSAD program. Clear acrylic was used as the material so that the flow structure in the interior could be viewed.

Testing revealed that the rejection velocities were too Low to entrain sufficient numbers of particles due to the

diameter of the inlet port and the relatively small mass flow rates employed in these experunents. Additionally, the

flow tended to "tunnel" through the particle bed which further precluded entrainment. Based on these results, a new

design was developed, with the goaJ of developing tully-turbulent flow inside the seeder plenum. The diameter of

the burner, which forms the outlet of the chamber is 1.65 mm. With an inlet diameter of approximately 0.1 ram, a

Reynolds number of roughly 2000 inside the seeder was achieved. This design was tested using a new type of seed

particle known as "Microspherical Feathers," manufactured bv Osaka Gas and discovered by Paul Oreenberg while

working on the LDV portion ot" this project previously described. These particles are essentially hollow spheres of

silicon dioxide, and are extremely monodisperse. They possess extremely large scattering cross sections and small

effective hydrodynamic diameters, both properties being advantageous for this application. Initial testing showed

that the particle entrainment was excellent and velocity vectors were determined using images captured both live and

from a pre-recorded sequence recorded in Sony BetaCam format. To stmplify the experimental configuration, the

illumination for these tests was provided by a CW argon-ion laser. The data reduction algorithm being utilized was

developed by Dr. M. P. Wernet of the Instrumentation and Control Technology Division of LeRC, and has been

previously de,%_:ribed.

Numerical aspects of modeling lor soot formation and radiation heat transfer have been completed. Soot transport

equations, the energy equation, and solutions for the radiative transport equaUon (RTE) have been incorporated into a

parabolic solver code for nonpremixed turbulent free-shear layer flows. The RTE can be solved by the YIX method

or via the method of spherical harmonics (PN). The former is considerably more accurate and suitable for

inhomogeneous media. It is disadvantageous, however, due to the requirement for long computation times. The

latter is computationally more expedient, but has been observed to exhibit numerical instabilities in the optically

thin limit. Iteractions are then required between the energy equation of these solutions. Reasonable agreement has

been found between predicted and measured soot volume t_-action and temperature data. The final part of modeling to

be completed is an accurate and efficient way for spectrally integrating the spectral radiative fluxes and properties.

Thermophoretic probe sampling measurements and subsequent TEM analysis for soot particle size and morphology

have been completed in the laboratory on propane and ethylene diffusion flames. Full-field laser-light extinction

measurements have also been successfully demonstrated. The tomogmphic inversion of the data to provide spatially

resolved mass fractions has also been demonstrated. These results are presently being assembled for publication. A

package has been constructed to perform both of these measurements in the LeRC 2.2 sec. drop tower. Data

elucidating primary particle size distributions for both propane and ethylene diffusion flames under both normal and

reduced gravity conditions has been successfully obtained and is being submitted for publication. Reduced gravity

measurements of soot volume fraction were not, however, completed before the shutdown of the 2.2 second tower

and hence will resume pending the av_ulability of this facility. In the interim, other methods are being pursued in

the laboratory., including interlacing fine, rapid response thermocouples between the probe grids, simultaneous

absorption/pyrometry measurements, and possibly flow-field mapping via laser doppler velocimetry.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/92 EXPIRATION: 9/96

PROJECT IDENTIFICATION: 93-2

RESPONSIBLECENTER: LeRC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Weiland, K.J.

786 (1993).

Intensified camera imaging of solid surface combustion aboard the NASA learjet. AIAA Journal. vol. 31,

i i i i|1 I lll I OI II II UI I I I I I I OI I OII II III I Ill Itl III I I OOI OOI I I iai II I oaoIII I II II I nI oI I I nII I ioi i oii aoI oI II I I I I I I I II III I al I lll II I II I OI I I I OOI I I I I OI aI I II I II I I I I I I I III oI I II oI III I I I uII I I l II oII I OI I I Ul I I III I I nuoI oI I OI I ni iao Iai II i i i I Ol i Ii i oill I I I OI OOaIII I I I III

11435
II. MSADProgramTasks -- Advanced Technology Development

i o o i o o o | | o g ill _. J o mn | J o| i a | I o o I o o s Io ia o | i J i i o i ! o | I oo I Io | i o o | | o | i i | | a o n I oo | !! o i o o |a o i o I o! ! nlI! nlII o | I | | I |nll I nl14o | I o H a | I o | | o II o | I o | | | i n i | | nJ | i | ni a | I I nlI ! o ! I o! I o o I o o I o o | I o ! Io nl In o | I o | I o nlI i o n I o |I o | i o | t I | i ! o i io n i Ln i nl| Ill I o |! | I | o 1 | o i| | | o | I | | I ! o o !I Io |1 o

SmaU, Stable, Rugged Microgravity Accelerometer

PRINCIPALINVESTIGATOR: Frank T. Hartley Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

P. Zavracky

P. Dolgin

Northeastern University

Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

The objective of this ATD task is to build a novel micromachined accelerometer that is capable of measuring

accelerations from 102g to 10-Sg with a better than 10Sg accuracy (<10gg/dHz) for the frequencies ltom 104 to 20

Hz. The device should have low temperature sensitivity and have a build-in calibration. The accelerometer must

withstand the launch environment. The task objectives include: 1) development of micromachined flexures;

2) development of an electronic parking mechanism; 3) development of active controls for the accelerometer, and

4) development of electronics lor data acquisition and control.

TASK DESCRIPTION:

The most important parameters are independent measurements of all three spatial components of acceleration, high

accuracy, and low-frequency measurements. The sensitivity, accuracy and frequency domain are determined by the

different acceleration sources that are found aboard the Space Shuttle and other spacecratt. The lowest frequency is

determined by the low Earth orbit period. The "as designed" device should be able to measure accelerations at

frequencies lower than 104Hz - 1/90 minutesl but the accuracy will decrease. Inertial navigation requires precise

positioning in space as well as the orientation tracking (sets of six or more accelerometers working as a

three-dimensional gradiometer). Seismology applications require high sensitivity in the presence of a constant

acceleration (g). All of these applications are possible with a flexure suspension and electrostatic actuation design

of the accelerometer. The flexure permits precise measurements of very small accelerations in the presence of a

large cross-axial acceleration. In other words, the accelerometer can measure the components of the acceleration

independently. The electrostatic actuation reduces temperature dependence and permits in situ calibration.

TASK SIGNIFICANCE:

The accelerometer will find applications in microgravity research, inertial navigation, seismology, geophysics,

planetary physics, and DoD programs. The device under development is optimized tot a microgravity application.

and additional applications should require only minor modifications.

PROGRESSDURINGFY1994:

The micromachined accelerometer is assembled from four parts, and all tour parts have been manut'actured, bonded

together, and tested. The data acquisition electronics has been built and passed thermal, vibration and EMI testing

at Lewis Research Centca. The control and measurement electronics has been designed and breadboarcled in readiness

for testing and characterization.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 10/92 EXPIRATION: 9/95

BS Students: 0 PROJECT IDENTIFICATION: 93-1

MS Students: O RESPONSIBLECENTER: JPL

PhD Students: 1

I nlnli | | | o|11 nlll nlnl| onloi ill nlll n l nl|| i nlnli i nlii | i ii|l nlu ill ill IIi iii nl! nlui i i nlll nll! ii I i onli i i i iii i1! i|11 nlnli nlii ! nli I nli nlnlnl| nll! i l i i onlol | ! o| | o| i i i i i nli ainli nlnli nlnli nl! nlunlI i iOl i i i i | | i nlll i nlnlnlo|1 nlll nlnli nlnll nlnlnll |i i| i nlnli nlnli nlnlinlnli nli i i l i i l Ioi aonlonli I i! o |i i nlnlilnli I nli I I i l aI I i mnl

11-636
|I. MSADProgramTasks-- Advanced Technology Development

High Resolution Pressure Transducer and Controller

PRINCIPALINVESTIGATOR:Dr. Elf E. lsraelsson Jet Propulsion Laboratory (JPL)

CO-INVESTIGATORS:

Prof. Peter Micheison

Prof. John Lipa

Dr. Martin Barmatz

Stanlord University

Stantord Universily

Jet Propulsion Laboratory (JPL)

TASK OBJECTIVE:

The objective of this project is to develop high resolution pressure transducers and controllers with many orders of

magnitude better performance than presently commercially available. The main use of these devices will be for

fundamental science investigations in the area of low temperature physics at helium temperatures.

TASK DESCRIPTION:

Two types of pressure transducers will be developed for use in the 1 to 10 bar pressure range. The first will utilize

a capacitive readout technique and will be capable of operating at any temperature from 300K to 2K. The second

will utilize inductive readout by means of a SQUID and will operate at helium temperatures only (2K to 7K). The

expected resolution of these transducers are about one part in 10 _°'and they will dissipate neglible amounts of heat

when operated. The pressure controller will be based on similar techniques as the transducers and will be capable of

controlling pressures in the 1 to 10 bar range over a limited pressure swing to near one part in 10 t°.

TASK SIGNIFICANCE:

The current capability of the MSAD program in fundamental low temperature physics is limited to controlling and

reading out one experimental variable, temperature, to sub-nano kelvin resolution at helium temperatures. By

providing a similar capability for a second variable, pressure, many new important flight investigations can be

performed. An example would be to test the validity of the Universality hypothesis in the theory of second order

phase transitions by performing high resolution measurements of some expertmental quantity at several fixed

pressures.

PROGRESSDURING FY 1994:

An initial version of the capacitive pressure transducer was designed and constructed. It employs a flexible Silicon

membrane which is sealed to a helium sample chamber with an Indium seal. Attached to the back side of the

membrane is a thin film capacitor plate. A second thin film capacitor plate is located a short distance away on a

fixed block of Silicon. Pressure variations in the sample cell will flex the membrane thereby adjusting the relative

capacitance of the circuit. For optimum reproducibility in the fabrication and assembly stages, the entire assembly

is produced using Silicon micro machining in existing JPL facilities. The assembled transducer was pressure tested

up to 10 bar and repeatedly cycled between room temperature and 77K without experiencing any leak problems. The

transducer is currently undergoing sensitivity testing using a thermal platform stabilized to nanokelvin temperatures.

A design lbr the superconducting pressure transducer was produced. Detailed design calculations were performed in

order to optimize performance in the 1 to 10 bar range. The design is similar to the capacitive version, except that

the flexing portion is a Niobium membrane. Pressure variations will be picked up by the changing distance

between the Niobium ground plane and a Silicon disk on which a set of thin film Niobium coils are laid down. The

resultant change in inductance will be read out by a commercial SQUID system. The photolithography mask for

laying down the coils on the Silicon disk have been procured and fabrication of the Niobium metal housing and

diaphragm have been completed. Assembly will be underway shortly.

II-637
STUDENTS FUNDED UNDER RESEARCH: TASK [NITIATION: 10/93 EXPIRATION: 9/96

BS Students: 1 PROJECT IDENTIFICATION: 963-01-04-00

MS Students: 0 RESPONSIBLECENTER: JPL

PhD Students: 0

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Israelsson, U.E., Echternach, P. M., Chui, T. C. P., Michelson. P. F.. and Lipa, J. A. "High resolution pressure transducer

and an on-orbit universality test." Proceedings of the 1994 Microgravity Low Temperature Physics Workshop,

Washington D.C., January, 1994.

!___e_||!|__|!_!!|___!|!|_____e__!!|!__!|_!__!__!|_!|!__!____|__|____!|!_!__|!___!|!!|_!__!_!!_!!__!____!|!!_|_!!|___!_!!!!_____!__!|o_e___!______o_||_!_!!|!|_|!||__|||!!||__|!__!___|_!|_||__|_______!|_!e_!__________o__!__!!_____!_!___!e!!|!||_

11-638
Surface Light Scattering Instrument

PRINCIPAL INVESTIC_TOR: Dr. William V. Meyer Ohio Aerospace Institute

CO-INVESTIGATORS:

Prof. J.A. Mann

Dr. P. Tin

R.B. Rogers

Case Western Reserve University

Case Western Reserve University

NASA Lewis Research Center CLeRC)

TASK OBJECTIVE:

The objective is the development of an instrument capable of detecting fluid surface phenomena (liquid/liquid and

liquid/vapor), such as local temperatures and interface temperature gradients, as well as surface tensions and volume

viscosity. This development is maturing with design and fabrication of many portions of the new instruments are

well underway.

TASK DESCRIPTION:

We started with a traditional room-sized surface light scattering instrument. Our instrument has evolved to a state

where the vibration sensitive bulk optics' high power, large space requirements in the traditional surface light

scattering instrument have been replaced by a low power, compact laser-diode surface light scattering system. This

includes a new "cat's eye" optics design that is immune to the sloshing of the surface being examined. This had

been been a major problem that kept this useful instrument from seeing commercial applications. A fiber optics

version of the insmunent is well underway; the ability to detect surface tension gradients (and temperature

gradients), using a set of acousto-optic modulator crystals placed in series in the fiber optics line, is being

implemented.

TASK SIGNIFICANCE:

This instrument will allow noninvasive, noncontact measurements of surface tension. From this, one can

extrapolate the local surface temperature (compared to bulk sLur'ace temperature) of a known clean sample.

Viscosity information is also provided. Until we implemented the auto-tracking optics, vibration encountered in a

regular laboratory environment made this instrument difficult to use. This means that a commercial version of this

instrument will now likely become a reality. Brookhaven Instruments (among others) has already expressed an

interest in making this happen, and has designed--and has provided---a custom version of their next-generation

correlator with this in mind. Additionally, this instrument will be valuable for reduced-gravity studies of critical

phenomena and interlace characterization.

Surlace tension is an elusive phenomena which controls many individual processes and everyday phenomena. It is

the two-dimensional analog of pressure and attempts to maintain the smallest possible surface area. It affects

cooking, cosmetics (improved formulation), tertiary oil recovery (20% - 30% more oil can be pumped from the

ground), detergents (better wetting of fibers), controlled release and targeted drug delivery (e.g. liposomes, what can

transport through the surface), materials processing (e.g. - steel making), etc. The study of surface tension driven

phenomena is often masked by gravitational forces which are not present in the reduced gravity environment of a

space station or space shuttle. This instrument provides not only a non-invasive measurement of surface tension

from which surface temperature can be extracted, it also gives the viscosity information. Viscosity is the internal

friction of a fluid (i.e. how thick or thin it is). This affects liquid crystal displays (fiat screens) used in computers,

etc.

PROGRESS DURING FY 1994:

Breadboarded grating systems (used with 680 nm and 780 nm laser diodes) with and without enhanced versions of

"cat's eye" optics. Breadboarded and successfully tested new anti-slosh optical train in both transmission and

11-639
II. MSAD Program Tasks -- Advanced Technology Development

reflection modes. Our surface tension measurements with the new optical train were better than 0.1% for

transmission mode (with low surface tension fluids: water, ethanol, acetone) and better than 0.5% for reflection

mode (with a high surface tension fluid, gallium). Designed and in process of building a completely fiber optic

surface light scattering system using polarization maintaining fiber couplers. Adapted surface light scattering

instrument to be usable as a heterodyning system, which permits non-invasive measurement of surlace tension,

viscosity and temperature gradients. Received BI-8050 correlator (built for us by Brookhaven Instruments); using

its unique data taking capabilities to analyze data taken with anti-slosh optics. Designed and had fabricated a graded

linear transmission filter which we will use in a high-amplitude (1-2 microns) spectrometer. Computer code/'or

thermocapillary ripples on a curved surface is nearly complete. It includes thin surface film effects, including

absorption, and it lays the foundation for a generalized theory of the dynamics of interlaces. Adapted laser

vibrometer to measure high amplitude ripplons on fluid surfaces. Successfully tested vibrometer on Putterman's

(UCLA) levitated drop experiment. Reported hardware developments at NASA's 1994 Fluids and Materials

Workshop and at SPIE's 1994 International Space Optics Conference.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 10/91 EXPIRATION: 9/95

BS Students: 0 PROJECT IDENTIFICATION: 92-4

MS Students: 1 RESPONSIBLE CENTER: LeRC

PhD Students: 1

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

de Mul, M. and Mann, Jr. LA. Muitilayer formation in thin films of thermotropic liquid crystals at the air-water interface.

Langmuir, vol. 10, 2311-2316 (August 1994).

Shih, R. and Mann, Jr. J.A. Response function of diacetylene monomolecular films spread on water by capillary wave

spectroscopy. Langmuir, (1994).

Presentations

Meyer, W.V., Tascharnuter. W.W., MacGregor, A.D., Dautet, H. Deschamps, P.. Boucher, F.. Zhu, J., Tin. P., Rogers,

R.B., Anasari, R.R. "Laser Light Scattering: From an advanced technology development project to experiments in a

reduced gravity environment." International Symposium on Space Optics. Garmish-Partenkirchen, FRG, EOS/SPIE Joint

Venture, April 18-22, 1994.

Meyer. W.V., Tin, P., Mann. Jr. J.A., Cheung, H.M., Rogers, R.B., Lading. L. "A preview of a modular surface light

scattering instrument with autotracking optics." International Symposium on Space Optics. Garmisch-Partenkirchen.

FRG, EOS/SPIE Joint Venture, paper 2210, April 18-22, 1994.

_|_*_*!_||_|_*|_t_|*_|_*_*||*_*_!_!_*_|_|*|_|_|*_!!|_*|!_|_!_e|_|!_!|_|||!!_|*_||_|||_!_|_||_|*_!_e|_|_|_||_!e_|_|!|!_*|_!|!_*_e_|!_*_!*_*_!*_!**|_*|!_*_e_|o|!_!e!_*|!!_e!_*_|_

11--640
Crystal Growth Instrumentation Development: A Protein Crystal Growth Studies Cell

PRINCIPALINVESTIGATOR: Dr. Marc L. Pusey NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The goal is to design and construct prototype cells which wilt permit study of the growth process of protein crystals

by a variety of techniques. Two cell designs are proposed. The first and most important will be Ibr studies of the

solution concentration gradients surrounding a growing crystal. The second design will be to study interfacial

features of protein crystals under growth and etching conditions. A second goal of the proposed work will be to

develop practical methods for protein storage prior to use in crystal growth (and other) experiments. The

characteristics desired for a Protein Crystal Growth Analysis Chamber system Ibr p.g growth studies are:

1. Several types of growth cells to accommodate specific study goals

2. Temperature control of the growth cell from 0-40 _+0.05 °C

3. Control of nucleation and growth of crystals at a defined location

4. A fluidic system to accurately prepare crystal growth solutions from stock solutions of protein,

precipitant, buffer, etc. and deliver them to the growth cell

5. The cells should be accessible lor addition.s to and/or modification of the solution

6. The ability to do follow-up experiments based upon preceding growth runs

7. Some cell adjustment to bring selected crystal faces in line (perpendicular or parallel) with the optical axes

8. Easy accessibility to other solution measurement systems (pH, conductivity, etc.) for maximum data return

9. Remotely operable from the ground to the maximum extent possible

10. Ability to maintain proteins in a viable state prior to use

TASK DESCRIPTION:

Current microgravity (I.tg) protein crystal growth (PCG) hardware systems are hybrid, attempting to both acquire

data about the processes of crystallization while growing crystals suitable for x-ray diffraction studies. This leads to

compromises in the design, with the result that neither approach is successfully accomplished. The proposed

hardware will be designed solely for studying the growth of protein crystals, which requires fewer experimental

growth cells, but each having the maximum amount of data return and control of solution physico-chemical

parameters.

For the upcoming year's effort the primary emphasis will be shifted from growth cell design to methods suitable tbr

protein storage during long term (3 months) gg missions. This will employ 8-12 different proteins, each stored in

two forms (in solution or as a freeze-dried powder) at three different temperatures (20 °C, 4 °C, and -20 °C). At

periodic intervals the stored material will be sampled and tested for changes in crystallizability, turbidity, and

structural and functional integrity. These measurements will determine if the net charge, molecular size, or shape,

of the protein have altered during storage. Concurrently with the above we will begin designing and testing

potential storage containers suitable for g use.

TASK SIGNIFICANCE:

In usage onboard an orbiting platlorm ground-based researchers will be able to monitor and change selected solution

parameters within the growth cells, and conduct tbllow-on experiments based upon recently acquired data. This will

enable the realistic studying of how pg al'fects the protein crystal growth process, and how it can be improved both

in space and on Earth. Long-term protein solution storage and stability will become a dominating concern as the

time scale of g experiments increases. Developing methods tor long-term protein storage will improve both this

and future g-based instrumentation.

I1-641
PROGRESS DURING FY 1994:

This project is a new start, building upon a previous one year proof-of-concept project. In that project, an initial

cell design was found to have flaws, primarily how to replace the solution within the cell without bubbling and the

designing of optical systems to pass through a curved glass interlace. A second cell design resulted which has a

square cross section, a volume of -4 ml's, and can accommodate a small peltier thermoelectric device for cold spot

crystal nucleation. Solution exchange is by flow through the cell. This cell is currently being tested for thermal

regulation, and the ability to grow protein crystals using the cold spot. The new cell design can maintain

short-term thermal regulation, measured on the surface of the growth cell when filled with liquid, within +0.015 °C

with minimal insulation and without the windows installed. Longer term fluctuations over __.0.05 °C are primarily

due to room temperature changes and the lack of protection from air currents. Power consumption when the heaters

are 100% on is 6.25 watts, and ~1 watt to maintain the cell at 12 °C above ambient once the set temperature has

been reached.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/94 EXPIRATION: 10/96

PROJECT IDENTIFICATION: 963-70-06

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC
Multizone Furnace Control Algorithm Development

PRINCIPALINVESTIGATOR: Dr. Bruce N. Rosenthal NASA Lewis Research Center fl.eRC)

Co-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

The objective of this ATD is to quantity the performance of a multivariable control system for eventual application

to multizone crystal growth furnaces.

Muitivariable control techniques are important because they can handle explicit coupling among furnace

components rather than treating the coupling dynamics as disturbances. The major justification for use of

multivariable furnace control is that thermal interactions exist between furnace heating elements. In a multizone

furnace these interactions may be strong enough that accounting for them explicitly by the controller can improve

performance. It has been our experience working with multizone furnaces that these interactions exist and they can

be signit]cant. Not only do interactions occur between heating elements, but also the ampoule, insulation and

outside disturbances contribute to interactions as well. Until now we have not quantified the extent of these

interactions and the ability of multivariable control methods to handle the complex nature of thermal interactions

expected in multizone furnace systems.

TASK DESCRIPTION:

Our approach is to quantify multivariable methods developed under prior ATD research by studying the pertormance

of multivariable control on a multizone test article. This will help us understand the controller performance in

terms of multizone heating. This research will involve two major tasks. The first task will concern the design and

construction of the multizone test article. The second task will concern the application and testing of the controller.

The controls aspect of this project will involve the expertise of Professor Celal Batur from the University of Akron.

TASK SIGNIFICANCE:

Quantification will establish a base-line performance index for use of this technology in future applications.

PROGRESSDURING FY 1994:

Multizone test article construction has been completed. Specification for the test article are:

• Room temperature to 700 C ° operation.

• 10 amp PWM power conditioning per element.

• Type K .005 inch ceramic insulated thermocouples

• 50 Mliz 486 computer control

• 16 bit ADC, 12 bit DAC

• Eight - 3 ohm, 30 volt .25 inch dia. incoloy sheath heating elements.

• Angle iron frame - 9 inch x 9 inch x12 inch outside dimensions. 1/2" thick insulated walls - alumina

sheet.

Two interaction indices are being used. Interaction Index 1 (II_) compares areas under the temperature step response

curves of each thermocouple. Interaction Index 2 (I/z) compares under the derivative of the temperature step response

curves of each thermocouple. The advantage of II2is it can distinguish between temperature responses involving

overshoots and undershoots. Initial comparisons have been made using the distance between the control

thermocouples and the heating elements as a variable. I12quantified the interaction of the distance variable showing

a spreading out of the temperatures as the distance increased. The trend was not as strong when using II_.

11--643
II. MSADProgramTasks-- Advanced Technology Development

,i,,i,H,oi,,iii,,aoolooii,ii, "_¢_¢i_1_i_I_I_I"_l|_Io_Q_;_I4_Q_I_I_|_IIII_H_sI_I_Io_o_o_I_o_Io_II_i_I_II_I_I_I_ H,Ji,olon,ou,ooaIIIoI,,a,oIaOI,oIa.II;I,¢I,uIa,nu.I

Remaining activities include identifying other variables for quantification including for example furnace wall

position, internal wall surface condition, and sample material. The project is scheduled for completion by

September. 1994.

STUDENTSFUNDED UNDER RESEARCH: TASK INITIATION: 10/92 EXPIRATION: 10/94

BS Students: 0 PROJECT IDENTIFICATION: 963-03-0C-00

MS Students: 0 RESPONSIBLECENTER: LeRC

PhD Students: 1

i i I II I I! I I i I oel Itl ioinloo o1! I el i I I I I I omI I oloI i i I I I I I oI IIg io! n I I I I oneai| o i| I I eI i i el I ! I III IoI I i i i I i i I i oIOil ill ill I I i i o! i! aI i I I I I I ol i ii II I i I I I oI I !I I Ill I ! I I I tl II I I i aI I i I I I oI ! I I I I IoonoI I I I oIII Il I ! I I ! I I i i I i i i ! i ai i i i i aI I I II I t aI ii nl I II I I I i i ni i i I i I I ! i I

11-644
II. MSAD Program Tasks -- Advanced Technology Development

Hi£_h Resolution Thermometr[/ and Improved SQUID Readout

PRINCIPALINVESTIGATOR: Dr. Peter Shirron

CO-INVESTIGATORS:

Dr. Michael J. DiPirro

Dr. James G. Turtle

Goddard Space Flight Center

Goddard Space Flight ('enter

Hughes/STX

TASK OBJECTIVE:

The objective of this work is _o develop two technologies which are becoming increasingly central h, h)w

tem_rature microgravity research: high resolution thennometers and Superconducting Quantum Interference

Devices (SQUIDs). A penetration depth thermometer (PDT) which uses thin fihn supercondulors is being

developed which can meet the performance ot existing paramagnetic salt thermometers, while offering greater

Ilexibitity and mununity lo particle radiation. Advanced SQUID sensors have been m,umfactured wilh I_lr belier

intrinsic energy resolulion Ihan commercitdly available sensors. These sensors use a second sulge array of 1()0-201)

SQUIDs to _m]plify tile signal from a single input SQUID. SQUID arrays and control electronics will be developed

and evaluated for potential use in spaceflight applications.

TASK DESCRIPTION:

This work is currendy proceeding ;dong two independent paths. First, PDT sensors are being fabricaled _md

evaluated. I)ifferent geometries _md film deposition techniques R)r are being explored to determine which factors

most signil]cantly impact the sensitivity and noise of the thermometer. Mea.surements of temperature sensitivity

and ultimate resolution will then be made reading out the thermometer with a commercial SQUID system. Second,

SQUID arrays which have been obtained from HYPRES, Inc. are being ev;duated in terms of noise, power

dissipation, and sensitivity to operating temperature and external magnetic fields. Control elccffonics will be

designed, fabricated, and lestetl with these sensors.

Eventually, a PDT will be fabricated to take advantage of the capabilities of the SQUID arrays which have

significantly lower input inductamce than commerci',d SQUIDs. The PDT czm either be made smaller and achieve

the same resolution or can be coupled through a transformer to achieve better resolution.

TASK SIGNIFICANCE;

When studying critical phenomena (for example, the lambda point of liquid helium), the focus is usually on how

certain p_mtmeters such as density or heat capacity change very close to the critic_d point. II ix crucial l(}r such

experiments to determine or control the thermodynmnic state to very high precision. Particularly m tile

microgravity environment, the precision to which temperature _md/or pressure c_m be ]ne_Lsured sets the limit for

science return. Adwmces in current state-of-the-;u-t for thermometry and SQUID sensors therefore translate mid

improvements in the quality of microgravity experiments. The SQUID technology will be particularly beneficial

since SQUIDs have a wide range of uses, both in spaceflight applications and in ground-b_Lsed laboratories.

PROGRESSDURING FY 1994:

1. Very uniform and high quality superconducting cylindrical _duminum fihns on sapphire mtmdrels have been

fabricated and tested. The lihns have been tailored in thickness to have superconducting transition temperatures m

the range of 1.2 to al-x)ve 1.8 K, though higher temperatures (>2.2K) are possible. Inductance measurements

indicate these films will realize better than the goal of 1 nanoKelvin/=ggHz temperature resolution when a

commerci_d dc SQUID is used for readout. Assembly and testing of a thermometer are underway.

2. The initial focus was to determine the sources of noise in our test apparatus for the SQUID arrays. Since the

intention is to be able to operate these SQUIDs in relatively unshielded environments, considerable effort was Sl',ent

distinguishing between noise which is intrinsic to the device and that arising from external sources. ('ouple(I t() this

11--645
effort was a determination of optimum operating conditions. Above frequencies of 300 Hz, we have succeeded in

demonstrating current resolution of 1.3 picoAmp/_/88Hz, just shy of the goal of 1 picoAmp/488Hz. This

corresponds to an energy resolution of 200 h, more than a factor of four better than commercial SQUIDs. Below

300 Hz the noise power spectrum exhibits a 1/f dependence, rising in amplitude to about 20 picoAmp/_/88Hz at 1

Hz. The emphasis for further work in this area will be to investigate 1/f noise reduction techniques, such as are

employed in commercial systems.

STUDENTS FUNDED UNDER RESEARCH: TASK INITIATION: 9/93 EXPIRATION: 8/96

PROJECT IDENTIFICATION: 963-70-70

RESPONSIBLECENTER: GSFC

I I o I I l I II II I I I a Ill I I I o II a ell i i i e o I I I I I oI I I I o ! i a I I a it a ii a i i I I | i i io Ii i i i i i a i i ii i i o | I e i I o I i i i ii i i iii i i i i i i i io i I i ! a i i i i i i i i I ai i i i i i i i o i i o i l 1a i II i ¢ o I I I I I I I I o o I I1 i I I a o I I I I I e ii o i I i i I o i i o ii i i I I I ¢ I oi ii i i s i i o e i I eil ei I I I ! I a I i o l io i i i i i i | I I | i ii a i i i i i i ii i ii i i

11-646
Determination of Soot Volume Fraction Using Laser-Induced Incandescence

PRINCIPALINVESTIGATOR: Dr. Karen J. Wetland NASA Lewis Research Center, (LeRC)

CO-INVESTIGATORS:

Dr. Randall Vander Wal NYMA, Inc.

TASK OBJECTIVE:

This project will develop a laser-based optical diagnostic technique, laser-induced incandescence (LII), lor the

measurement of soot volume traction. The major objectives are to obtain the hardware and choose a combustion

system of interest that yields relatively high soot concentrations, verify and develop the technique in the laboratory,

including establishing LII on a quantitative basis, demonstrate LII in a laboratory flame under a variety of

conditions and geometries, conduct reduced-gravity tests with LII and other complementary optical measuremenl.s,

and assess the usefulness of LII as a measure of soot volume traction.

TASK DESCRIPTION:

We intend to develop laser-induced incandescence (LII) as a two-dimensional nnaging diagnostic for the

measurement of soot volume fraction for microgravity combustion research. LI1 in conjunction with other optical

imaging techniques, would provide unparalleled temporal and spatial resolution, and therelore, yield insight and

sensitivity into soot formation and oxidation processes. Present methods of measuring soot volume fraction are

limited to line-of-sight methods. These methods offer poor temporal and spatial resolution and require assumptions

about the path length and soot physical properties. LII utilizes the spatial and temporal properties of pulsed laser

excitation to heat soot to far greater temperatures than ordinary flame temperatures and exploits the resultant

blue-shifted incandescent emission from the laser-heated soot. The incandescence is predicted theoretically to be a

measure of soot volume fraction, which is the feature of soot that governs many physical processes such as

radiative heat transfer from flames. This technique will be extended to two-dimensional imaging applications and

will be calibrated against gravimetric sampling.

TASK SIGNIFICANCE:

Successful development of this diagnostic technique will provide detailed data on soot formation, growth, and

oxidation processes tot a variety of combustion systems, which may lead to a better understanding and control of

sooting processes in flames.

PROGRESSDURING FY 1994:

Manufacturers were contacted regarding capabilities of their lasers for performing in a reduced-gravity environment.

Initially, a premixed fiat flame produced on a McKenna burner was chosen for technique verification.

Our primary goal was to determine how to minimize laser-induced and natural interferences, maximize the signal,

and ensure a known dependence of the signal upon soot volume traction. A pulsed Nd:YAG laser provided the

excitation light at either 1064 or 532 nm. All technique verification measurements were performed in a premixed

ethylene/air fiat flame and stabilized by either a chimney or fiat plate. For laboratory, demonstration measurements,

a small coflow burner was chosen. Combustion measurements were performed on heptane and decane droplets

supported by an optical tiber.

Spectrally-resolved scans over the range of 300 to 900 nm of the emission from the laser-heated soot lor 532 nm

excitation were obtained. The data obtained at a low laser intensity with a prompt gate of 50 nsec, show bands at

308 and 342 nm, assignable to OH emissions, which are nontinearly dependent upon the 532 nm laser intensity.

An additional peak at 850 nm was observed at all laser intensities and is attributed to excited oxygen atom emission.

Slight changes in the laser beam quality significantly alter the spatial power density, and cause significant variations

in the observed photochemical interferences. A delay between the laser pulse and detection allows any molecular and

photofragment emission to decay but allows sufficient LII signal to be collected.

11-647
Etnission scans using 10_4 nm excitation for two different laser pulse power intensities and collection gates lack

signific:mt photochemic_fl el]ecls. Although soot absorbs less at 1064 nm than at 532 nm. the power available

trom the laser is sufficient to heal the soo! to incandescent temperatures. For most of Ihe subsequent

measurements, 1064 nm light is used.

We measured the measured variation of the signal with laser intensity for two collection wavelengths centered at 425

um and 550 nm and two different C/O ratios for an excitation wavelength of 10(_ rim. A clear saturation regime

exists near 100 to 150 MW/cm 2 where the signal is quite independent of the laser power, in excellent agreement

with calculations. Similar behavior is found for 532 nm excitation, although at a lower intensity. Operation in

this region ensures that slight attenuation of the laser beam due to absorption through the soot field does not affect

the observed signal.

The time-resolved behavior of the LII signal detected at 450 run was studied. The decays at a particular wavelength

are phenomenological averages reflecting a range of initial "incandescent" temperatures and rune-vary, ing

contributions of various cooling processes. The signal obtained at low laser intensity is best fil with a single decay

tune of 130 _+5 nsec and is interpreted as the temporal response of the laser-heated soo! to the cooling of the

particle by a combination of conductive, convective and radiative processes. At high laser intensities the majority

of the incandescence nearly tracks the laser pulse. The fit is a sum of two exponenw, d time decays of 9 _+1 and 50

± 10 nscc. The rapid temporal response of the LI1 signal observed at high laser intensity is in good agreement with

the response curve calculated by Melton for a single carlxm particle of 20 nm diameter irradiated with a laser

intensity of 100 MW/cm:.

We obtained the dependence of the LII signal on soot volume fraction by comparison to conventional line-of-sight

extmction measurements. There is demonstrated lineanty between the LII signal and soot volume fraction at two

different detection wavelengths. The linearity of the LII signal over an order of magnitude in s(×)! volume fraction

produced by the different C/O ratios encourages the use of LII for quantitative measurements of soot volume

fraction.

One-dmm,_sional radial profiles were obtained of the soot. Even though visually the flames appear cylindrically

unilbm_ at a given axial height, lhe s(_t fields are not uniform. The immediate utility of such plots is that one

obtains a less ambiguous measure of the path length through the flame as opposed to that from natural flame

images. Single laser shot, two-dimensional images were obtmned in a coflow diffusion flame, both vertically and

horizontally. In both images, the camera detects no scattered light, and no background luminosity from the flame.

Sequences of images can bc used to build a three-dimensional picture of the soot in the flame.

hnages of the nalural llame luminosity of a burning decane droplet were obtained/tom a second c_unera 260 ms after

igmtion. The flame is elongated in the opposite direction of the gravitational vector; as a result of natural

convection. To the eye, the base of the flame near the lower half of the droplet is blue while the very luminous

region above the droplet is yellow. Temporally-resolved LII images were taken of the same test. The displaced

location of the soot evolved from the burning droplet flame was located predominantly _ts a conic',fl section m the

w',tke region above the droplet. Higher camera intensifier gains, which led to saturation of the L[I sign_ in the

upper flame region, did not reveal any soot in the bottom portion of the flame.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 10/93 EXPIRATION: 9/97

PROJECT IDENTIFICATION: 94-2

RESPONSIBLECENTER: LeRC

11-648
lI. MSAD Program Tasks -- Advanced Technology Development

i i, I I¢ | I i 01, | i _ 01 !I IIi | i i Ill I I |, I Ie 011 | I I 0111 ! I ¢ I I ¢ I, g I I I ¢ I I D, I, I I J11 t I I SI III I ¢ II I I I I I I III I I I II I I III I t I ! I I J | II I I I e I I 1111111111, I I | I I I, I I I I 14111, I | | ! I QI I I I ! ¢ I II | I,, 01 !, I I I_, II 11 $ I I 11. I 11 H I| _ !, I I, I ! I ¢ I I I, ! | _ I I I II I, ! ¢, I I I I III I ¢, I_ q I |, I I I m11111, I I

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Vander Wal. Randall L. and Weiland, Karen J. Laser-lnduced incandescence: development and characterization towards a

measurement of soot volume fraction. J. Applied Physics B. (in press).

Presentations

Vander Wal. Randall, L., Dietrich, Daniel L. and Weiland, Karen J. "Laser-induced incandescence: characterization and

applications." poster presentation at the 25th Symposium (Internationall on Combustion, Irvine, CA. August 5. 1994.

Vander Wal, Randall, L., Dietrich, Daniel L. and Weiland, Karen J. "Applications of laser-induced incandescence (LII) in

diffusion flames." Spring Meeting of the Central States Section of the Combustion Institute, Madison, Wisconsin. June

6-7, 1994.

I 1111 eI II IoI I I JIt I l I I ! I lI I,I J I. 11 oI( * fill 101 II II I I, 11l I I I 111111 ! 111, I! I I ! II oIll I IS l l oill Oli¢lll IO! II! Ill onl III nl .QI Ill Olllll! IS OIII III lllellllU IO I Ill ell ollO llO I Ii Ii i 1111 ii is i II iii fill Ill Ill el I Ill! lll, Jl! I I I 111 II I Ili J I! Ole I i I ii ! I, iii i Ill Ill JI

11--649
II. MSAD Program Tasks -- Advanced Technology Development

*lit IIIIIIIIIIIIIllllllllDt IlllllllllllUll!ll011 j__!__I_m_i_i_I_M_I_i__|_||_!_I_

Multi-Color Holography

PRINCIPAL INVESTIGATOR:Mr. William K. Witherow NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

No Co-l's Assigned to this Task

TASK OBJECTIVE:

A noncontact method of simultaneously determining concentration and temperature variations in fluid systems is

underway. An additional benefit will be the additional simultaneous data acquisition capability and thus a possible

reduction in the number of experiment runs required per mission.

TASK DESCRIPTION:

In this system, two fluid parameters will be varied simultaneously, and this technique will measure the variations

by using two different frequency lasers.

TASK SIGNIFICANCE:

More complete multivariable research on fluid science experiments will be enabled by this new capability.

PROGRESSDURINGFY1994:

Experiments have been performed involving simultaneous concentration and temperature gradients in sugar

solutions and salt solutions. Gels have been investigated lor possible use so that the concentration gradients can be

more stable, but it has been lound that even at low concentrations they have such a high optical density that they

cannot be used. A breadboard system that can be flown on the KC-135 has been constructed. The system uses a

diode laser at 680 nm wavelength and a diode pumped frequency doubled Nd-YAG laser at 532 nm wavelength. The

system uses fiber optics to guide the beams to the desired locations. Phase shifts for phase shifting interferometry

are induced by a pizeo-electric cylinders which have several turns of the fiber optic cables wound around them. A

computer system for automated data collection and analysis has been constructed.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 10/91 EXPIRATION: 9/94

PROJECT IDENTIFICATION: 963-70-01

NASA CONTRACT No.: In-house

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Journals

Vikram, C.S., Witherow, W.K., and Trolinger, J.D. Algorithm for phase difference measurement in phase shifting

interferometry. Applied Optics, vol. 32, 6250-6252 (1003).

Presentations

Witherow. W.K., Rogers, J.R., Facemire, B.R., Armstrong, S.D., Trolinger, J.D., Webber, D, and Vikram, C.S. "Methods

to detect and measure gradients in fluids and materials processing." 6th International Symposium on Experimental

Methods for Microgravity Materials Science, San Francisco, CA, February 28, 1994.

I Ie I oI Itl l III Ill llll IIII III III I lU I II I II I II II I III III I MIlll III I II II I I II II I II I I II III III III I II III III I II II I III III I III II I III I II I I I III Iltl III II I III I III II I III III I II I IIIIIII iii I II III III III III Ilnl I II Ill III III I III II IIII I II I III III III III III II I II III I III III

1I--650
Ceramic Cartridges via Sintering and Vacuum Plasma Spray

PRINCIPALINVESTIGATOR:Mr. Frank R. Zimmerman NASA Marshall Space Flight Center (MSFC)

CO-INVESTIGATORS:

No Co-I's Assigned to this Task

TASK OBJECTIVE:

The objective of this development work is to provide a manufacturing process for containment cartridges used in

high temperature (1200 ° to 2000 °C) crystal growth furnaces. A thermal spray process is being used to build up

refractory metals and ceramics into a containment cartridge for high temperature, single crystal semi-conductor

growth experiments. This process uses high energy plasma inside a low pressure (100-200 torr) inert environment

to apply layers of material onto a removable mandrel. A variety of materials are being characterized and evaluated

against a demanding set of requirements, including high service temperature ( 1700 °C), oxidation resistance, and

resistance to liquid metal attack. Techniques to spray form refractory metals (tungsten, molybdenum, niobium,

tantalum) and ceramics (alumina, boron nitride) are being developed in the Plasma Spray Cell at Marshall Space

Flight Center. These plasma spray formed materials are evaluated for mechanical properties, density,

microstructure, and resistance to liquid semiconductor attack.

TASK DESCRIPTION:

A thermal spray process is being used to build up reli_actory metals and ceramics into a containment cartridge for

high temperature, single crystal semi-conductor growth experiments. This process uses high energy plasma inside a

low pressure (100-200 torr) inert environment to apply layers of material onto a removable mandrel. A variety of

materials are being characterized and evaluated against a demanding set of requirements, including high service

temperature (1700 °C), oxidation resistance, and resistance to liquid metal attack. Techniques to spray form

refractory metals (tungsten, molybdenum, niobium, tantalum) and ceramics ('alumina, boron nitride) are being

developed in the Plasma Spray Cell at Marshall Space Flight Center. These plasma spray formed maten_ds have

been evaluated for mechanical properties, density, microstructure, and resistance to liquid metal attack. Forming

techniques and the resultant mechanical and metallurgical properties will be presented.

TASK SIGNIFICANCE:

NASA's Crystal Growth Furnace (CGF) has flown on the United States Microgravity Lab (USML-1) nussion to

conduct single crystal growth work on a variety of semiconductor materials. These semiconductor crystals (GaAs,

CdZnTe, HgZnTe, HgCdTe) are grown in quartz ampoules surrounded by insulation, thermocouples, and other

inslrumentation. The entire experiment is contained within a Sample Ampoule Cartridge (SAC), a._shown in

Figure 1, which facilitates handling and installation into the furnace. The SAC also functions as a containment

system, which is required to protect the flight crew from the highly toxic materials used in these crystal growth

experiments. If the ampoule containing the crystal growth material should rupture, these cartridges provide a

necessary level of containment. The containment requirement is complicated by the fact that most of these crystal

growth compounds are known to aggressively attack most common structural metals at furnace operating

temperatures. Currently, these cartridges are made of materials which are attacked at rate that will not fully

penetrate the cartridge within the duration of the experiment. For experiments of longer duration, a more

chemically resistant material is required to assure no breach in the contmnment will occur. Regardless ()1 the

material u_d, the current manufacturing sequence is labor intensive, dependent upon product availability, and

contains several fabrication steps and joining processes.

ii i ill l ll*ll|lllllnlnllilnlillii*|l i iii iiililll*lllll|l i 1011 i llnlllaiililOililllielllllilli|lillllalileinlnlnl|l|lllllllni|lllnlll I I lllllllllllll I lell I llOi lall I II |111111111 I I11 lllllil II I II 1111 I11 a II i I! 111 Ill 111 I I I I It I 1¢ IIll I, I I el 1111 ii iI I

!I-651
II. MSADProgramTasks-- Advanced Technology Development

i| o i i e ! i I i i s I i | II | i i | I I | in o |i o | i i | i n i i ill Io II o | ! | | i | o n i i | i !* | io ! ! i o i a t | i i ! o i t o Io oo i o I I t n I o v i o | i oo i i o i I o I I o n i o ! | o| # o ! t o | I ! | I Io I! o ! I o H e I I ! I I oo II o I ! o I i i i i | | I| i I | o n e o i | g n i o o i io !I o ! o e i 11 * I I * o I o! o | ! i a i | i o| i o II u g e ii to! wla |g I ! o| ii| oog iI* olo I! * ! Ig ! |1

PROGRESSDURINGFY 1994:

Vacuum plasma spray parameters were developed for a variety of refractory metals and ceramics. These parameters

were scaled up to produce over 220 full size (24 in. long by 1.0 in. diam) monolithic cartridges on reusable graphite

mandrels.

Compatibility tests were conducted with most of the available refractories in Ga, GaAs, Ge and high temperature

furnace environments.

Aluminum oxide and silicide coatings were demonstrated as effective oxidation barriers for protecting the underlying

reflactory metal.

VPS formed refractory cartridges can meet leak rate and pressure requirements of several crystal growth fumaces

under consideration or planned for flight.

STUDENTS FUNDEDUNDER RESEARCH: TASK INITIATION: 10/93 EXPIRATION: 10/95

PROJECT IDENTIFICATION: 963-70-05

NASA CONTRACT NO.: In-house

RESPONSIBLECENTER: MSFC

BIBLIOGRAPHIC CITATIONS FOR FY 1994:

Proceedings

Zimmerman, F.R. "VPS forming of refractory metals and ceramics for space furnace containment cartridges." Proceedings

of the ASM Thermal Spray Conference, Thermal Spray Industrial Applications. Boston. MA, 457-461 (1994).

Presentations

Zimmerman, F.R. "Themal spray forming of refractory sample ampoule cartridges for single crystal growth space

furnaces." AIAA Conference. Microgravity Sciences Hardware Session, Huntsville. AL September 27, 1994.

i i i i i I iI II I I ! i i I I I I I I I oI I! I I I I I oI I ii i II III i I I oi i i I I i i I II I i ii i i I I ! I I! I I i oI I I I I I I I | I I I I II oi i I ! I I | I ii i Ii i tll I ! I I | I I I II I I I I I I I I I i II I t I I I I I I I I I I II I I I I i i i i ill i OI I OI I ! I I I I I I II I OI I II I II I I I I t II II I II I III I I I II i ii i I i i ili i i i i ii i ii i I i i I I I II tl I I I I I i iI I I I I I n I II

11-652
III. MSAD Program Tasks-- FY1994 Bibliographic Citations

III.

Microgravity Science & Applications

Bibliographic Citations for FY 1994

• Flight Research Tasks

Benchmark Science ......................................................... III-655

Biotechnology ................................................................. III-656

Combustion Science ....................................................... III-657

Fluid Physics ................................................................... III-661

Materials Science ............................................................ III-665

• Ground Research Tasks

Benchmark Science ......................................................... III-671

Biotechnology ................................................................. III-674

Combustion Science ....................................................... III-678

Fluid Physics ........................................................ , .......... III-682

Materials Science ............................................................ III-694

• ATD

Advanced Technology Development .......................... III-705

How to Order Publications Cited in this Document:

Copies of many of the documents cited in the bibliography published here are available from the Center for

AeroSpace Information (CASI), a NASA Scientific and Technical Information (STI) program facility. Prices are

determined by the number of pages of each document and whether paper or microfiche copy material is ordered.

NASA Center for AeroSpace Information (CASI)

P.O. Box 8757

Baltimore, MD 21240-0757

Telephone: 301 621-0390, FAX: 301 621-0134

111-653
II. MSAD Program Tasks -- FY1994 Research Disciplines

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1II-654
III. MSAD Program Tasks -- FY1994 Bibliographic Citations

i i i i i| i i i i ill iii i| i i i 11 ii I i o iii i ii i i t i i J i I I I ti i ia i I i e i i i Di a i i ii ii i t i i i i | J i i _ i a ii ill i i | i iii i i i i i| i i i i i ! i i i ii | i i | i i i | ! i i i o 11 iii iii i w! I I ! !I i Ii i | i i i I o I i I 0 _ I I II I J I i I I I I I * | iii i | i ! i i i ! i i i | ! 011111111 J i i | i | i | i i i ii I ii i i I I _ Ho iiI| le |i I n | | i | iii i| i i i i ! i i |

Flight: Benchmark Science

Adriaans, M.J.. Swanson, D.R.. and Lipa. J.A.

Physica B, w)l 194, 733-734 (1994).

The velocity of 2nd sound near the lambda-transition in superfluid He-4.

Bhattacharjee, J.K. and Ferrell. R.A. "Corrections to dynamic scaling for the critical ultrasonic attenuation in a

one-component fluid." Proceedings of the NASA Workshop on Low-Temperature Physics, Washington. DC, January,

1994.

Briggs M.E., and Gammon R.W. "Photothermal deflection in a supercritical fluid." Paper at the Conference on Optical

Characterization of Coatings and Substrates, Symposium on Optical Interface Coatings, Grenoble, France, June 6-10,

1994.

Chui, T.C.P., Swanson, D.R., Adriaans, MJ.. Nissen, J.A., and Lipa, J.A. Temperature noise measurements in the

cannonical ensomble. Physica B, w}l 194, 23-24 (1994).

Coleman, M. and Lipa, J.A. Heat capacity of helium confined to 8 micron cylinders near the lambda point. Phys. Rev.

Lett., in press. (December 1994).

Duncan, R.V. "Progress and review of DYNAMX." Pre-SCR Review, Washington D.C., January 1994.

Duncan. R.V., Boyd, S., and Moeur, R. "Critical dynamics in microgravity." International Symposium on Order and

Disorder, Santa Barbara CA, 1994.

Duncan. R.V., Boyd, S., Moeur, W.. Robinson, S., Akau, R., and Gianoulakis, S. Critical dynamics in microgravity.

International Journal on Thermophysical Properties, in press, (1994).

Duncan, R.V., Boyd. S.. Moeur. W.. Robinson, S., Akau, R.. and Gianoulakis, S. "Critical dynamics in microgravity."

Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Ferrell, R.A. Singular correction to dynamic scaling for a fluid. Physica A, (1994).

Ferrell, R.A. and Bhattacharjee, J.K. "An experimental prediction for CHeX." Proceedings of the NASA Workshop on

Low-Temperature Physics, Washington, DC, January, 1994.

Ferrell, R.A. and Moldover, M.R. On the limitations imposed by the Earth's gravity on measurements of the critical

viscosity of a one-component fluid. Ann. der Phys., (1994).

Gammon, R.W., Shaumeyer, J.N.. Boulari. H., Briggs, M.E., and Gent. D.A. "Zeno: Critical fluid light scattering from

xenon in microgravity." Invited talk at the 12th Symposium on Thermophysical Properties. Boulder, CO, June 19-24,

1994.

Li, W.B., Serge, P.N., Gammon, R.W.. and Sengers, J.V. Small-angle Rayleigh scattering from nonequilibrium

fluctuations in liquids and liquid mixtures. Physica A. Vol. 204, 399 (1994).

Li, W.B., Sergwe. P.N., Gammon, R.W.. and Sengers, J.V. Determination of the temperature and concentration

dependence of the refractive index of a liquid mixture. J. Chem. Phys., Vol. 101, 5058 (1994).

Lipa, J.A., Adriaans, M.J,, and DiPirro, M.J. "Mission concept for a new test of the universality hypothesis using order

parameter measurements below the lambda transition of helium." Proceedings of the NASA/JPL 1994 Microgravity Low

Temperature Physics Workshop.

Lipa, J.A.. Swanson, DR., and Nissen, J.A. "Heat capacity and thermal relaxation of bulk helium very near the lambda

point." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

I t II I I Ill l II l III I II I I I I II Ill l II Itl III iii III I el I I l I I l I I l II I I I I l I I l I I I II II II I I I l I I I l I I I I U; il l I III III I III I tl l Ill U l I II I II I I I II I l II I II l II I I I l I I I I I I l III II I I I I I I I I I I II I l Ill I I I l Ill el I l leO I II l III III l III I I I I l Il I Il I l I II I Ill l II l tl I I I III l l lI I I l l I Ill III II I

!11-655
Citations III. MSADProgramTasks--FY1994 D_wio_rapn_c

Lipa, J.A., Swanson, D.R., Nissen. J.A.. and Chui. T.C.P.

the lambda point. Physica B, vol 197, 239-248 (1994).

Heat capacity and thermal relaxation of bulk helium very near

Lipa, Lambda-point experiment in microgravity. Cyrogenics, voi J.A., Swanson, DR., Nissen. J.A., and Chui, T.C.P.

34, no 5, 341-347 (1994).

Mason. P.V., Strayer, D., Petrac, D.. Gutt. G., Warfield. K., Worden, P.. and Torii, R. "The control of liquid Helium in

space by electrostatics for the satellite test of the equivalence principle experiment." Proceedings of the 39th Cryogenics

Engineering Conference, Advances in Cryogenic Engineering, vol 39.

Nissen, J.A.. Chui, T.C.P., and Lipa, J.A. The specific-heat of confined helium near the lambda-point. Physics B, vol

194, 615-616 (1994).

Nissen, J.A., Chui, T.C.P., and Lipa, J.A. The specific-heat of confined helium near the lambda point. J. Low Temp.

Phys., vol 92, 353-366 (1993).

Nissen, J.A., Swanson, D.R., Qin, X. Salvino, D., Lipa, J.A.. Chui, T.C.P., Israelsson, U., and Gasparini, F.M. "The

confined helium experiment in microgravity." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics

Workshop.

Swanson. DR., Nissan. J.A., Chui, T.C.P.. Williamson. P.R., and Lipa, J.A. Optimization and performance of

high-resolution thermometers in low-earth orbit. Physica B, vol 194, 25-26 (1994).

Swartwout, M.A., and Worden, P.W. "Error analysis for the QuickSTEP." Proc. Seventh Marcel Grossman Meeting on

General Relativity, Stanford University, 1994.

Worden, P. "The Quick STEP instrument and science." Proceedings of the Seventh Marcel Grossman Meeting on General

Relativity, Stanford University, 1994.

Flight: Biotechnology

Ban, N.H.. Escobar, C., Gaarcia. R., Hasel, K.. Day, J.. Greenwood. A., and McPherson. A. "Crystal structures of an

anti-idiotypic fab and of the idiotype-anti-idiotype complex." Proc. Natl. Acad. Sci. USA, 91, 1604-1609 (1994).

Cudney, R., and McPherson. A. Screening and optimization strategies for macrmolecular crystal growth. Acta Cryst., vol.

D50, 414-423 (1994).

Day, J., Ban, N., Patel, S., Larson, S.B., and McPherson, A. Characterization of crystals of satellite panicum mosaic

virus. J. Mol. Biol., vol. 238. 849-851 (1994).

DeLucas, L.J., Long, M.M., Moore, K.M., Rosenblum, W.M., Bray, T.L., Smith C., Carson, M., Narayana, S.V.L., Carter,

D., Clark, D., Clark, Jr., A.D., Nanni, R.G., Ding J., Jacobo-Molina, A., Kamer, G., Hughes, S.H., Arnold, E., Einspahr,

H.M., Clancy, L.L., Rao, G.S.J., Cook. P.F., Harris, B.G., Munson, S.H., Finzel, B.C.. McPherson, A., Weber. P.C.,

Lewandowski, F., Nagabhushan, T.L., Trotta, P.P., Reichert, P.. Navia, M.A., Wilson. K.P., Thomson, J.A., Richards,

Felden, B., Florentz, C.. Gieg6, R., and McPherson, A. A histidinylatable tRNA-like fold at the 3' -end of satellite tobacco

mosaic virus RNA. Nucleic Acids Res., vol. 22, 2882-2886 (1994).

Gibson, W.M., and MacDonald, C.A. "Polycapillary Kumaldaov optics: a status report." X-Ray and UV Detectors, SPIE

Proc., 2278, 156-167 (1994).

Gudi, T., and Hymer, W.C. "GRP94: A molecular chaperone in rat pituitary tissue." Thirteenth Summer Symposium in

Molecular Biology, The Pennsylvania State University, University Park, PA, August, 1994.

Hymer. W.C., Shellenberger, K., and Grindeland, R. Pituitary cells in space. Adv. Space Res., vol. 14, 61-70 (1994).

i ii i i olll i is jl i l ill ii i illl j el iii i is ill el a ill ii I ill ill el I ill nl ill is i i ii i i ii o aii i a i el o i iii i illlllllaa ill 1oa ill o Ill ill lee eel e o i Ill Ill III I Ill I OI Ilia el i Ill Oil eeoc Dee laciest! eeloete lea oe I el! eel| le| lea i el so ! eeeeee|le|leailul! n! lollletlloinl Ill el! !

II1-656
Larson. S.B.,Greenwood, A..Cascio, D..Day,J..andMcPherson. A. The refined molecular structure of pig pancreatic

t_-amylase at 2.1 ,_ resolution. J. Mol. Biol.. vol. 235, 1560-1584 (1994).

MacDonald, C.A., Abreu, C.C., Budkov, S., Chen, H., Fu, X., Gibson, W.M., Kardiawarman, Karnaukhov, A., Ponomarev,

I.Y., Rath. B.K., Ullrich, J.B.. Vartanian, M., and Xiao, Q.F. "Quantitative measurements of the performance of capillary

X-ray optics." Multilayer and Grazing Incidence X-ray/EUV Optics 1I. SPIE Proc., 2011 (1993).

Malkin. A., and McPherson, A. Light scattering investigations of nucleation processes and kinetics of crystallization in

macromolecular systems. Acta Cryst., vol. D50, 385-395 (1994).

McPherson. A. "Crystallization of Biological Macromolecules" in "Handbook of Crystal Growth." Edited by: T. J. Hurle

w)l. 2 A, pp 419-463, 1994.

McPherson. A. "The Role of X-ray Crystallography in Structure Based Rational Drug Design" in "Rational Drug Design."

CRC Press, 1994.

Patel, S., Cudney. and McPherson, A. Crystallographic characterization and molecular symmetry of edestin, a legumin

from hemp. J. Mol. Biol., w_l. 235, 361-363 (19941.

Patel, S., Cudney, R., and McPherson. A. Using a silica hydrogel for macromolecular crystallization. Acta Cryst., vol.

D50. 479-483 (1994).

Perez, F.M., Deaver, D.R., and Hymer, W.C. "Why use a flow cytometer for cell analysis'?" in "Endocrine Research

Techniques." Edited by: F. de Pablo, C.G. Scanes, and B.D. Weintraub Academic Press, Inc., pp 157-179, 1993.

Rhodes, P.H., and Snyder. R.S. "Chapter 3, Theoretical and Experimental Studies on the Stabilization of Hydrodynamic

Flow in Free Fluid Electrophoresis" in "Cell Electrophoresis." Edited by: J. Bauer CRC Press, Inc., 1994.

Rhodes, P.H., Snyder, RS., and Roberts, G.O. "Role of dielectric constant in electrohydrodynamics of conducting fluids."

2nd Microgravity Fluid Physics Conference. Cleveland, OH. June 21-23. 1994.

Snyder, R.S., and Rhodes, P.H. "The NASA electrophoresis program." The International Aerospace Congress, IAC '94,

Moscow, Russia, August 15-19, 1994.

Ullrich, J.B., Gibson, W.M., Gubarev. M.V., and MacDonald, C.A. Potential for concentration of synchrotron beams

with capillary optics. Nuclear Instruments and Methods. vol. A347. 401-406 (1994).

Ullrich, J.B., Kovanstev. V., and MacDonald, C.A. Measurements of polycapillary X-ray optics. J. Appl. Phys., vol. 74,

5933-5939 (1993).

Ullrich, J.B., Ponomarev, I,Y., Gubarev. M.V., Gao, N., Xiao, Q.F., and Gibson, W.M. "Development of monolithic

capillary optics for X-ray diffraction applications." X-Ray and UV Detectors, SPIE Proc., 2278, 148-155 (1994).

Weisgraber, K.H., Newhouse, Y.M., and McPherson, A. Crystallization and preliminary X-ray analysis of human plasma

apolipoprotein C-I. J. Mol. Biol., vol. 236, 382-384 (1994).

Wentink, R., Carbone, J., Aloise, D., Gibson. W.M., MacDonald, C.A., Hanley, Q.E., Fields, R.E., and Denton, M.B.

"Charge injection device (CID) technology: an imaging solution for photon and particle imaging applications." SPIE

Proc., 2279 (1994).

Flight: Combustion Science

Bahadori, M.Y.. Stocker, D.P.. Vaughan, D.F, Zhou, L., and Edelman. R.B. "Effects of buoyancy on laminar, transitional,

and turbulent gas jet diffusion flames," in "Modern Developments in Energy, Combustion, and Spectroscopy." Edited by:

eddited by F.A. Williams, A.K. Oppenheim, D.B. Olfe, and M. Lapp. Pergamon Press, Oxford, pp 49-66. 1993.

uann uau!oloolall!o!o!ollall!o!uollo!loooo!o!!oa!o|oo!nnnon aeon|on!ohio ioolool uol u| o!lln|l!| i!onl|¢aooaooaolao!nl!o!|na|n aononon oolollu uonn!onaoulo!o|onno|noon|oloooa|l!onaololonaoooooooonaln aolooooo|! uo!a oool*l!nnllnloolonlonoon#looo| lion alloooo|l

111457
1Fa_'L'I." __ __1[-; Citations

III. MSAD Program Tasks -- FY1994 mmxograpmc

Bhattacharjee. S.. Altenkirch. R.A.. and Sacksteder, K.R. The effect of ambient pressure on flame spread over thin

celluosic fuel in a quiescent, microgravity experiment. To appear in J. of Heat Transfer. (1994).

Bhattacharjee, S., Bhaskaran, K.K., and Altenkirch, RA. Effects of pyrolosis kinetics on opposed-flow flame spread

modeling. Combustion Science and Technology, Vol. 100, 163 (1994).

Bhattacharjee. S.. Charles, T.L.. and Altenkirch, R.A. "Modelling gas-phase radiation from laminar flame spreading over

solids." ASME Winter Annual Meeting, New Orleans. November 1993.

Bullard. D.B.. Tang, L., Altenkirch. R.A.. and Bhattacharjee, S. Unsteady flame spread over solid fuels in microgravity.

Adv. Space Res., vol.13, no.7, 171-184 (1993).

Butlard, D.B.. Tang, L., Altenkirch, R.A., and Bhattachariee, S. Unsteady flame spread over solid fuels in microgravity.

Adv. Space Res., vol. 13, no. 7, 171-184 (1993).

Card, J.M. Asymptotic analysis for the burning of n-heptane droplets using a four-step reduced mechanism. Combustion

and Flame, (1993).

Ching-Biau, Jiang and T'ien, James S. "Numerical computation of flame spread over a thin solid in forced concurrent flow

with gas-phase radiation." accepted for presentation at the Eastern States Section Meeting of the Combustion Institute

(December 1994).

Choi, M.Y., Dryer, F.L., Green, G.J. and Sangiovanni. J.J. "Soot agglomeration in isolated, free droplet combustion."

AIAA Paper No. 93-0823, January 1993.

Dryer, F.L. Computational/experimental studies of isolated, single component droplet combustion, Second International

Microgravity Combustion Workshop, NASA Conference Publication 10113. NASA Tech Brief, 291-196 (1993).

Faeth, G.M. "Soot morphology and optical properties in nonpremixed flame environments." Proceedings of the Spring

Technical Meeting, Canadian Section of the Combustion Institute. Kingston. ON, Canada. 2-1 to 2-5. 1994.

Faeth, G.M. "Issues in premixed and nonpremixed combustion." DOE Workshop on Fundamental Research in Support of

Industrial Combustion Needs. Irvine, CA, 1994.

Faeth, G.M., Sunderland, P.B.. Koylu. U.O. and Urban, D.L. "Laminar jet diffusion flames in microgravity: A paradigm

for soot processes in turbulent flames." Proceedings of International Symposium on Aerospace and Fluid Sciences.

Tohoku University, Sendai, Japan. 185-198, 1993.

Farias. T.L.. Carvalho, M.G., Koylu. U.O. and Faeth. G.M. "A computational study of the absorption and scattering

properties of soot." Proceedings of the Fall Technical Meeting, Eastern Section of the Combustion Institute. Pittsburgh,

PA, 394-397, 1993.

Farias, T.L., Carvalho. M.G., Koylu, U.O. and Faeth, G.M. Computational evaluation of

Rayleigh-Debye-Gans/fractal-aggregate theory of the absorption and scattering properties of soot. J. Heat Trans, tin

press).

Farias, T.L., Carvalho, M.G.. Koylu, U.O. and Faeth, G.M. "Scattering properties of polydisperse soot aggregates."

Eurothem Seminar No. 37: Heat Transfer Radiating and Combusting Systems -2, Saluggia, Italy, in press, October 1994.

Fendell, F.E.. Bush. W.B., Mitchell. J.A., and Fink IV, S.F. Diffusion-flame burning of fuel-vapor pockets in air.

Combustion and Flame, vol. 98, 180-196 (1994).

Ferkul, P.V. and T'ien, J.S. A model of low-speed concurrent flow flame spread over a thin fuel. Ct_mbustion Science and

Technology. to appear, vol. 99, 345-370 (1994).

Femandez-Pello. A.C. "Smoldering combustion in microgravity: from ground to space shuttle experiments, ."

Proceedings of the International Symposium on Aerospace and Fluid Sciences, Sendal, Japan. 243-273, 1993

i I I I III III i I I I I I I I I i i Ii I II I i i i I i i i I Iiii i iI I I i i I I I I I I I I I III I I I I I I I I I I i i i i i II I I i i I i I I III II I II I I I I I I III I I iI I i I I I I I I i I II I I I I I I i i i I I I iI II I ! I I I i i I i i i i i ii i II I I I I I I I i i I i i t i it i i i i i i I ! I I I I It I I I I I i i I I I I I II I I I I I i i i i i ii i i i i i i i I i I i Ii I I I i I i i ia ii i i i i I I I i I I i Ii I

111--658
III. MSAD Program Tasks -- FY1994 Bibliographic Citations

Femandez-Pello, A.C. "Smoldering combustion in microgravity: from ground to space shuttle experiments." Lecture,

COSPAR '94 Conference, Gl-Symposium on Microgravity Sciences: Results and Analysis of Recent Space Flights,

Hamburg, Germany, July 1994.

Hege, U.G. Heat release effects on the instability of parallel shear layers. AIAA journal, vol. 32, no, 1, 206-207 (1994).

Hege, UG., Zhou, L., and Bahadori. M.Y. "Transitional and turbulent gas-jet diffusion flames in microgravity." Paper

AIAA-94-0432, AIAA 32nd Aerospace Sciences Meeting, Reno, NV, January, 1994.

Jiang, C., T'ien, J.S. and Ferkul, P.V. "Numerical computation of buoyant upward flame spread and extinction over a thin

solid in reduced gravity." presented to the Central States Section Meeting of the Combustion Institute, Madison

Wisconsin. June 5-7, 1994.

Koylu, U.O. and Faeth G.M. Optical properties of overfire soot in buoyant turbulent diffusion flames at long residiner

times. J. Heat Trans., vol. 116, 152-153 (1994).

Koylu, U.O. and Faeth, G.M. Optical properties of soot in buoyant laminar diffusion flames. J. Heat Trans, (in press).

Koylu, U.O., Faeth, G.M., Farias, T.L., and Carvalho, M.G. "Fractal and projected structure properties of soot

aggregates." Combust. Flame. in press.

Koylu, U.O.. Sunderland, P.B.. Mortazavi. S. and Faeth, G.M. "Soot nucleation and growth in weakly-buoyant laminar jet

diffusion flames." 32nd AIAA Aerospace Sciences Meeting, Reno. NV. AIAA Paper No. 94-0561, 1994.

Law, C.K. and Faeth, G.M. Opportunities and challenges of combustion in microgravity. Prog. Energy Combust. Sci.,

vol. 20, 65-113 (1994).

Lozinski. D., Buckmaster. J.D. and Ronney, P.D. Absolute flammability limits and flame balls in optically thick

mixtures. Combustion and Flame, vol. 97, 301-316 (1994).

Marchese, A.J. and Dryer, F.L. "Computational modeling of transient methanol droplet vaporization." presented at the

Easter States Section of the Combustion Institute Meeting, October 1993.

Marchese, A.J. and Dryer, F.L. "Transient modeling of the combustion of bi-component liquid droplets: methanol/water

mixtures." presented at the Easter States Section of the Combustion lnstiture Meeting, 1994.

Marchese, A.J.. Dryer, F.L. and Choi. M.Y. "Theoretical basis for estimated test times and conditions for drop tower and

space-based droplet burning experiments with methanol and n-heptane." MAE Report No. 1999, Princeton University,

August 1994.

Miller, F.J., Ross, H.D., and Schiller, DN. "Temperature field during flame spread over alcohol pools: Measurements and

modelling." Accepted at the Eastern States Section of the Combustion Institute Fall Technical Meeting, Clearwater Beach,

FL, 1994.

Miller. F.J., Ross, H.D., and Schiller, D.N. "Rainbow schlieren deflectometry of flame spread over liquid pools: A

comparison of experimental and numerical results." Poster at the Twenty-Fifth International Symposium on Combustion,

Irvine, CA. 1994.

Olson. S.L.. Hegde, U. "Imposed radiation effects on flame spread over black PMMA in low gravity." Fall Technical

Meeting of the Eastern States Section of the Combustion Institute, December 5-7, Clearwater Florida, 1994.

Pearlman, H.G. and Ronney, P.D. Self-organized spiral and circular waves in premixed gas flames. Journal of Chemical

Physics, vol. 101, 2632-2633 (1994).

Pearlman, H.G. and Ronney, P.D. Near-limit behavior of high Lewis-number premixed flames in tubes at normal and low

gravity. Physics of Fluids. vol.6, 4009-4018 (1994).

111-659
III. MSADProgramTasks-- FY1994 Bibliographic Citations

Pearlman. H.G.and Ronney, P.D. "Near-limit behavior of high Lewis-number premixed flames in tubes at normal and low

gravity." Spring Technical Meeting, Combustion Institute. Central States Section, Madison, WI. June 6-7, 1994.

Ramachandra, P.A., Altenkirch. R.A.. Tang, L. Wolverton, J.K.. Bhattacharjee, S. and Sacksteder, K.R. "The behavior of

flames spreading over thin solids in microgravity." Twenty-Fifth Symposium (International) on Combustion, to appear in

Combustion and Flame, L994.

Ronney. P.D. "Requirements design review: structure of flame balls at low Lewis-number (SOFBALL)." NASA Lewis

Research Center, Cleveland, OH, Oct. 14, 1993.

Ronney, P.D., "Combustion at zero-gravity," Dept. of Mechanical Engineering." University of Southern California. Los

Angeles, CA, November 1993.

Ronney, P.D. "Preliminary design review: structure of flame balls at low Lewis-number (SOFBALL)." NASA Lewis

Research Center, Cleveland, OH, May 17. 1994.

Ronney, P.D. Laser versus conventional ignition of flames. Optical Engineering, vol. 33, 510-521 (1994).

Ronney, P.D. "Propagation and extinction mechanisms of premixed turbulent flames." Joint U.S./Japan Workshop on

Mathematical Modeling in Combustion and its Interaction with Numerical Computation, Kaapa, HI, July 25-29. 1994.

Ronney, P.D., Whaling, K.N.. Abbud-Madrid. A., Gatto. J.L.. and Pisowicz. V.L. Stationary premixed flames in spherical

and cylindrical geometries. AIAA Journal, vol. 32, 569-577 (1994).

Sacksteder. K.R. and T'ien. J.S. "Buoyant downward diffusion flame spread and extinction in partial gravity

accelerations." Presented at the Twenty-Fifth Symposium (International) on Combustion, The Combustion Institute,

1994.

Sacksteder. K.R. and T'ien J.S. "Buoyant downward diffusion flame spread and extinction in partial gravity accelerations."

presented to the Micro-Gravity Measurements Group Meeting #13, Montreal Quebec Canada, September 1994.

Shultz, D.A., Matkowsky, B.J., Volpert, V.A. and Femandez-Pello, A.C. Propagation and extinction of forced opposed

flow smolder waves. Combustion and Flame (in press), (1994).

Stocker, D.P., Olson, S., Torero, J.L. and Fernandez-Pello, A.C. Microgravity smoldering combustion on the USML-1

shuttle mission. ASME 1993 Winter Ann Meeting, New Orleans. LA. vol. 269, 99-110 (1993).

Sunderland, P.B. and Faeth, G.M. "Soot formation in hydrocarbon/air laminar jet diffusion flames." Proceedings of the

Fail Technical Meeting, Eastern Section of the Combustion Institute, Pittsburgh, PA, in press, December 1994.

Sunderland, P.B., Koylu, U.O. and Faeth, GM. "Soot formation in weakly buoyant acetylene-fueled laminar jet diffusion

flames burning m atr. 25th Symposium (International) on Combustion. Irvine, CA, August 1994.

Sunderland, P.B., Koylu, U.O. and Faeth, G.M. "Soot formation in hydrocarbon-fueld jet diffusion flames burning in air."

25th Symposium (International) on Combustion. The Combustion Institute, Pittsburgh, poster paper, abstract only,

1994.

Sunderland, P.B., Koylu, U.O., Faeth, G.M. "Soot formation in acetylene-fueled laminar jet diffusion flames burning in

air." Proceedings of Spring Technical Meeting, Central States Section, The Combustion Institute, Pittsburgh, 275-280.

1994.

Sunderland, PB., Mortazavi, S., Faeth, G.M. and Urban, D.L. Laminar smoke points of nonbuoyant jet diffusion flames.

Combustion and Flame, vol. 96, 97-103 (1994).

Sunderlasnd, P.B., Koylu, U.O. and Faeth, G.M. "Soot formation in weakly buoyant acetyleme-fuled laminar jet diffusion

flames burning in air." 25th Symposium (International) on Combustion, Irvine, CA, Combust. Flame, in press, August

1994.
Torero. J.L., and Fernandez-Pello. A.C. Natural convecti_m sm_flder of polyurethane foam, upward propagation. Fire

Safety Journal, (in press), (1994)

Torero, J.L. and Fernandez-Petlo. A.C. "l)_wnward sm_,lderin_z of p.lyurcthane foam ." Proceedings of the Fourth

International Symposium on Fire Safety im prcss_ 19_M.

Torero, J.L., Femandez-Pello, A.C. and Urban, II. l:xperimental observati_ms of the effect of gravity changes on

smoldering combustion. AIAA Journal. vol. 35, 5, 991-996 il994).

Tse. S.O.. Sanchez. C. and Fernandez-Pello, A,C. "Smoldering in the presence of a gas/solid interface and its transition to

flaming." 1993 Fall Meeting, Western States Section/The Combustion Institute, October 1993.

Tse, S.O., Sanchez, C.G., Fuiita, O. and Fernandez Pcllo. A.C. "Smoldering in the presence of a gas/solid interface and its

transition to flaming." Work-in-Progrcss Pc_stcx, Twenty-l_ifth International Symposium on Combustion. Irvine, CA,

August 1994.

Vander Wal. R., Dietrich. D.. and Choi, bd.Y. "Rclativc so_t v_flume iractions in droplet combustion via laser-induced

incandescence." Presented at the Eastern States Section ol the C{_mbustion Institute, Clearwater, FL, December 5-7, 1994.

West. J. Bhattachaxjee, S. and Altcnkirch, R.A. Sur/acc radialit_n cllcct,s on flame spread over thermally thick fuels in an

opposing flow. J. Heat Trans.. 116. 646 651 (1994).

West, J., Bhattacharjee, S,, and Altenkirch, R.A. St_rlace ,adiation effects m_ flame spread over thermally thick fuels in an

opposing flow. J. of Heat Transfer, v_fl. 116. 646-65l (1994).

West, J., Bhattacharjee, S., and Altenkirch, RA. Surlace radiation effects on flame spread over thermally thick fuels in an

opposing flow. J. heat Trans., vol. t16, 646 651 (1994).

West, J., Bhattacharjee, S., Rameriez, B and Altcnkirch, R.A. "l_t_w Reynolds number flow near the leading edge of a

burning and non-burning plate in a mocrogravity environment." a,IAA/ASME Thermophysics and Heat Transfer

Conference, Colorado Springs. CO June 20 23. 1994.

Williams, F.A. Studies of droplet burning and exlmclii,n, Second International Microgravity Combustion Workshop,

NASA Conference Publication 10113. NASA Tcch gricf, 283 290(1993).

Zhang, B.L., Card, J.M. and Williams, FA. "Application of rate ratio asymptotics to the prediction of extinction for

methanol droplet combustion." Western States Section of the Combustion Institute. March 1994.

Zhu, J.Y. and Ronney, P.D. Simulation of fron_ propagation at large non-dimensional flow disturbance intensities.

Combustion Science and Technology (in pressl, vol. 10(1, 183-201 (1994).

Flight: Fluid Physics

Berg, F.F. and Gruner, K. Remarkably small critical cxponent fi_t the v_scosity of a polymer solution. J. Chem. Phys.,

vol. 101, 1513 (1994).

Berg, R.F. "Hydrodynamic similarity in an oscillating body viscometer." 12th Symposium on Thermophysical

Properties, Boulder, CO, June 19-24, 1994.

Bousman, W.S. and Dukler. A. "Studies of gas-liquid fl_w in microgravity: Void fraction, pressure drop, and flow

patterns." Presented at the 1993 WA ASME Meetiqg, New Orleans, November 1993.

Bousman, W.S. and Dukler, A. "Ground based studies of gas liquid llows in microgravity using learjet trajectories." AIAA

paper 94-0829, presented at AIAA Aerospae Sciences Meeting, Rent. January 1994.

III-661
Bousman, W.S. and McQuillen. J.B. "Characterization of annualar two-phase gas-liquid flows in microgravity." presented

at the Second Microgravity Fluid Physics Conference, Cleveland. OH. January 1994.

Burkersroda, C.V., Prakash. A. and Koster. J.N. Interracial tension between fluorinerts and silicone oils. accepted by

Microgravity Quarterly, (1994).

Chang, A. "Scaling analysis of thermocapillary flows in cylindrical containers." Ph.D. thesis, August, 1994.

Chen, Q., and GarofL S. "Dynamic contact angles and interface shapes at high capillary, number." American Physical

Society Meeting, Pittsburgh, PA. March. 1994.

Chen, Q., Rame, E., and Garoff. S. "Measuring dynamic contact angles: an experimental study of the breakdown of present

theory." AIChE Annual Meeting, San Francisco, CA. November 1994.

Cui, C., and Goree, J. Fluctuations of the charge on a dust grain in a plasma. IEEE Transactions on Plasma Science, v01.

22, 151-158 (1994).

Forbes, Rashidnia, N. and Balasubramaniam. R. "Abel inversion of irregularly spaced discrete interferometric fringe data:

A geometrical approach." Division of Fluids Dynamics Meeting, American Physical Society, Albuquerque, New Mexico,

November. 1993.

Garoff. S., Chen, Q., Rame. E., and Willson, K.R. "Microscale hydrodynamics near moving contact lines." Second NASA

Microgravity Fluids Conference, Cleveland. OH, June 1994.

Garoff, S., Chen, Q., Rame, E., and Willson, K.R. "Microscale hydrodynamics near moving contact lines." Proceedings

of the 2nd NASA Microgravity Fluids Conference, Cleveland, OH, June. 1994.

Gaudet, S., McKinley, G.H., Stone, H.A. in AIAA, 32nd Aerospace Sciences, Reno NV. p.1, 1994.

Goree, J. Charging of particulates in a plasma. Plasma Sources Science and Technology. vol. 3. 400-406 (1994).

Goree, J. "Plasma crystals." AIAA 32rid Aerospace Sciences Meeting, Symposium on Microgravity Science, Reno, NV,

Janaury 10-13, 1994.

Goree, J.

Goree, J.

Goree, J.

"Plasma crystals." NASA Microgravity Fluid Physics Conference, Cleveland. OH, June 12-13, 1994.

"Dusty plasma exoeriments and theory." UCSD Plasma Physics Seminar. June. 1994.

"Dusty plasma experiments and theory." Invited talk at the Workshop on Non-Neutral Plasma, July, 1994.

Goree, J., and Chiu, Y.T. Dust contamination of the spacecraft environment by exposure to plasma. J. of Spacecraft and

Rockets, vol. 30, 765-767 (1993).

Hallinan, K.P., Chebaro, H.C., Kim, S.J. and Chang, W.S. Evaporation from a capillarity-resupplied extend meniscus

within a cylindrical pore for non-isothermal interracial conditions, accepted for publication to J. of Thermophysics and

Heat Transfer, (1994).

Hart, J.E., Albaiz, A., and Leben. R. Flow separation and chaos in a rotating annulus. Computational Fluid Dynamics,

vol. 2, 59-72 (1993).

Hart, J.E., and Brummell, N. High Rayleigh number _-convection. Geophys. and Astrophys. Fluid Dyn., vol. 68, 85-114

(1993).

He, Q. and Hallinan, K.P. "Thermocapillary effects on the evaporating extended meniscus." accepted for presentation at

the ASME-WAM, Chicago, IL, November 5-8, 1994.

I I I I I I III III I11 III IIII III I II III I I I III III I III III III I II I I I I I I III Itl I II I I I I I I I I I I I I ii II I III III I II I iii i II I I I I I I I I I II I I I I I i i i I i II I II I I I I i i I II I I III II I I I I I I II I I I I I II II I I II I I I! I I I II I I II I II I II III I III I II I I I I II I II Itl III I II I II II III III II I I I I ii i II I II I II I II I I

111-662
III. MSAD Program Tasks-- FY1994 Bibliographic Citations

Kamotani. Y.. Ostrach. S. and Pline, A. "Some results from surface tension driven convection experiment aboard USML-I

spacelab." Paper AIAA-94-0238, 32nd AIAA Aerospace Sciences Meeting, Reno, NV. January 10-13. 1994.

Kamotani, Y.. Ostrach. S. and Pline. A. "Some Velocity Results from the thermocapillary flow experiment aboard USML-1

Spacelab." COSPAR Meeting, Hamburg. German. 1994.

Kamotani, Y.. Ostrach. S and Pline. A. Analysis of velocity data taken in surface tension driven convection experiment in

microgravity. Physics of Fluids A. vol. 6. no. 1l. 3601-3609 (1994).

Kamotano, Y.. Ostrach, S. and Pline. A "A thermocapillary convection experiment in microgravity." I993 ASME Winter

Annual Meeting, New Orleans, LA, Nov.-Dec. 1993.

Kondos, P.A. and Subramanian, R.S. "Buoyant flow driven by a time-dependent gravitational field in a two-dimensional

cavity." AiChE Annual Meeting, San Francisco. November 1994.

Lee, C.P. and Wang, T.G. Acoustic radiation pressure. J. Acoust. Soc. Am., vol. 94, 1099-1109 (1993).

Lee, H.S. and Merte, H. Jr. Vapor bubble dynamics in microgravity, report NASA Contract NAS-3-25812. Report No.

UM-MEAM-93-10. The University of Michigan, Department of Mechanical Engineering and Applied Mechanics. NASA

Tech Brief. (December, 1993).

Macari, E.J.P.. Sture, S., and Runesson, K. Prediction of response of granular materials at low effective stress levels. J.

Geotechnical Engineering, vol. 120. no. 7. 1252-1268 (1994).

Merte, H. Jr. "Nucleate pool boiling in microgravity and variable gravity." Department of Chemical Engineering,

Clarkson University, Potsdam, New York, December 7, 1993.

Merte, H. Jr. "Nucleate pool boiling in microgravity - results from STS-47." NASA SSSAAS meeting (Space Station

Science and Applications Advisory Subcommitte) Houston, Texas, Feb. 16. 1994.

Merte, H. Jr. "Gravity effects on liquid/vapor phase change." Two Seminar Series presented in the Department of

Mechanical Engineering at McMaster University, seminar entitled: "Condensation Heat Transfer under High Gravity, and

Pool Boiling in Microgravity and Variable Gravity. Hamilton, Ontario. May 11, 1994.

Merte, H. Jr. and Lee, H.S., Keller, R.B. "Pool boiling experiment prototype model flown on STS-47 (PBE-IA)," report

NASA contract NAS 3-25812. Report No. UM-MEAM-93-10. The University of Michigan, Department of Mechanical

Engineering and Applied Mechanics. (December, 1993).

Peric, D., Runesson, K., and Sture, S. "Effect of pore fluid compressibility on localization of elastic-plastic solids under

undrained conditions." Proceedings of the US National Congress for Applied Mechanics. Seattle, WA (1994).

Peric, D., Sture, S., and Runesson, K. Effect of pore fluid compressibility on localization in elastic-plastic solids. Int. J.

Solids and Stuctures, vol. 32, no. 4, (1994).

Praburam, G., and Goree, J. "Observations of particle layers levitated in an rf sputtering plasma." Gaseous Electronics

Conference, Montreal, Canada, October, 1993.

Praburma, G., and Goree, J. "Observations of particle layers levitated in an rf sputtering plasma." American Physical

Society Meeting, Division of Plasma Physics, November, 1993.

Prakash, A. and Koster, J.N. Penetrative convection in sublayer of water including density inversion. Warme-und

Stoffubertragung, 29, 37-49 (1993).

Prakash, A. and Koster, J.N. Convection in multiple layers of immiscible liquids in a shallow cavity - Part II: steady

tbermocapillary convection. International Journal of Multiphase Flow. 20. 397-414 (1994).

e!__|!|__|n__|!____!!_!!_!!e|_|__|_!_______!!_s____|___ee_||__!_|__|___!_|___!!_!|__!_____!____|______!s_|||_$_|!||!!|!!______|__¢!!¢!__!__||_|___!__|_e!||_____!||__|___|_________s!___||__|||__!_||______|__||||||||||__|!_|_____s_|____!__|!_|__

i11-6 6 3
Ill. MSAD Program Tasks-- FY1994 Bibliographic Citations

Prakash, A. and Koster. J.N. Thermucapillary convection in three immiscible liquid layers, accepted by Microgravity

Quarterly, (1994).

Prakash, A. and Koster, NN. Natural and thermocapillary c_mvection in three layers. European Journal of Mechanics

B/Fluids, 12, 635-655 (1993).

Pratt, D.M. and Hallinan, K.P. "An investigation of thermocapitlary effects on a heated capillary re-supplied meniscus for

low bond numbers." accepted for presentation at the 3rd Latin American Symposium on Fluid Mechanics, Caracas,

Venezuala, February 5-8, 1994.

Rame, E. "The boundary condition at a moving contact line: an experimental study of the interpretation of the dynamic

contact angle." American Physical Society/Division of Fluid Dynamics. Atlanta. GA. November 1994.

Russel. W.B., and Sperry, P.R. Effect of microstructures on the viscosity of hard sphere colloids and modulus of

composites. Progress in Organic Coatings, w)l. 23. 305 {1994).

Rutgers, M.A., Dunsmuir, J., Russel, WB., and Chaikin. P.M. Crystalline fluidized beds. Physical Review E, (to appear).

Rutgers, M.A., Dunsmuir, J., Russel, W.B., and Chaikin. P.M. Hard sphere equation of state. Science. (submitted).

Saville, D.A., and Sankaran, S. Experiments on the stability _1 a liquid bridge in axial electric field. The Physics of Fluids

A, vol. 5, 1081-1083 (1993).

Saville, D.A., and Sankaran, S. "Electrohydrodynamic control of capillary instabilities with neutrally buoyant liquid

bridges." APS Fluid Dynamics Meeting, Albuquerque, NM. November, 1993.

Schmitt, T., Koster, J.N., and Hamacher, H. Particle design for displacement tracking velocimetry, accepted by

Measurement Science and Technology, (1994).

Spiegelberg, S.H., Gaudet, S.. McKinley. G.H. Second Micrngravity Fluid l)ynamics Conference, Cleveland, OH, 1994.

Subramanian, R.S., and Kondos, P.A. "Gas bubble dissolution and growth in glass melts." invited review. American

Ceramic Society Meeting, Indianapolis. Indiana, April 1994.

Thomas, H., Morrill, G., Demmel, V., Goree, J., Feuerbacher, B., and M6hlmann, D. Plasma crystal: coulomb

crystallization in a dusty plasma. Physical Review Letters. wd. 72. 652-656 (1994).

Tong, W. and Koster, J.N. Penetrative convection in sublayer _1 water including density inversion. Warme-und

Stoffubertragung, 29, 37-49 (1993).

Wang, T.G., Anilkumar, A.V., Lee, C.P. and Lin, K.C. Core-centering of compound drops in capillary oscillations:

Observations on USML-1 experiments in space. Journal of Colluis and Interface Science, vol. 165, 19-30 (1994).

Wang, T.G., Anilkumar, A.V., Lee, C.p. and Lin, K.C. "AIAA Paper No. 93-0252. {1993)." A preliminary analysis of the

USML-I drop dynamics experiment results.

Wei, H. and Subramanian, R.S. Interactions between two bubbles under isothermal conditions and in a downward

temperature gradient. Physics of Fluids A, A6, 9, 1971-78 (1994).

Willson, K.R., and Garoff, S. "Dominant factors controlling dynamic wetting of PDMS fluids." American Physical

Society Meeting, Pittsburgh, PA, March, 1994.

Willson, K.R. and Garoff, S. "Dominant factors controlling dynamic wetting of PDMS fluids." 68th ACS Colloid and

Surface Science Symposium, Stanford, CA, June 1994.

Willson, K.R. and Garoff, S. Effect of chain termination chemistry and molecular weight on dynamic wetting of polymer

liquids, to be published in Colloids and Polymers. (August 1994).

111-664
Flight: Materials Science

Abbaschian. R., Gokhale, A.B., DeWitt, R.. Cambon. G.. Favier. J.J.. Coriell. S.R.+ and deGroth, llI. H.C. "In situ

monitoring of crystal growth using MEPHISTO." Proceeding of the Microgravity Materials Science Conference,

Huntsville, Alabama, May, 1994.

Ahuja, S.. Stefanescu. D.M.. and Dhindaw, B.K. "Role of processing/system parameters on the interaction between

liquid/solid interfaces and insoluble particles." Cast Metal Matrix Composites. Proceedings of the 2nd International

Conference, D.M. Stefanescu and S. Sen. eds.. AFS, Des Plaines, IL, 44-56 (1993).

Alexander, J.ID. Residual gravity .jitter effects on fluid processes. Microgravity Science and Technology, vol. 7. no. 2,

131-136 11994).

Alexander. LID. "What factors determine the influence of spacecraft attitude motions, vibration, and transient

disturbances on convective transport in Bridgman systems'?." COSPAR "94, Hamburg, Germany, July, 1994.

Alexander, LID. "Scaling and estimation of experiment response to g-jitter." ESA Physical Science Working Group

Meeting, ESA HQ, Paris. FRance, September 9, 1994.

Alexander. J.ID., and Rogers, M,JB. "Passive accelerometer system: measurements on STS-50 (USML-I)" Proceedings

of the Joint Launch + One Year Science Review of USML-1 and USMP-I with the Microgravity Measurement Group, NASA

Conference Publication 3272, vol. 2. 569-578, 1994.

Andrews, J.B. "Solidification of Immiscible Alloys" in "Immiscible Liquid Metals and Organics." Edited by: L. Ratke

DGM Informationsgesellschaft, Verlag Press, pp 199-222, 1993.

Andrews. J.B. "Coupled growth in hypermonotectics." NASA Microgravity Materials Science Conference. Huntsville,

AL, May 24-25, 1994.

Andrews, J.B., Hayes, L.J., and Coriell, S.R. "Instabilities during coupled growth of hypermonotectics." COSPAR 30th

Scientific Assembly, Hamburg, Germany, July 11-21, 1994.

Andrews, J.B., Hayes, L.J., and Moss, CB. "Factors influencing coupled growth in hypermonotectics." TMS Fall

Meeting, San Francisco, CA, February 27-March 3, 1994.

Arikawa. Y., Andrews, J.B., Coriell, SR., and Mitchell, W.F. "Modeling and numerical simulation of processes at a

hypermonotectic solidification front." Proceedings of the 6th International Conference on Experunental Methods for

Microgravity Materials Science. TMS. R.S. Schiffman and J.B. Andrews. eds., 137-140 (1994).

Arikawa, Y., Andrews, JB., Coriell, S.R., and Mitchell, W.F. "Modeling and numerical simulation of processes at a

hypermonotectic solidification front." TMS Annual Meeting, San Francisco, CA, February 27-March 3, 1994.

Arnold, William A. and Matthiesen, David Numerical simulation of the effect of shearing on the concentration profile in a

shear cell. Journal of the Electrochemical Society, in press,

Arnold, William A., Matthiesen, David, Bennett, Robert J. and Jayne, Douglas T. "Numerical simulation of diffusion

experiments using a ground-based shear cell." AIAA paper #94-0797, 3 lnd AIAA Conference, 1994.

Bayuzick, R.J., Hofmeister, W.H., Morton, C.W., and Robinson, M.B. "Effects of nucleation by containerless

processing." NASA Microgravity Materials Science Conference. Huntsville, AL, May. 1994.

Belhadjhamida, A., Johnson, J. L., Tandon, R. and R. M. German. Advances in liquid phase sintering. Journal of

Materials Synthesis and Processing, vol. 1, 275-285 (1993).
Biao,Y..Azoulay. M..George. M.A.. Burger, A., Collins, W.E.. Silberman. E.. Su. C.H.. Volz. M.P., Szofran. F.R., and

Gillies. D.C. Photoluminescence of vapor and solution grown ZnTe single crystals. J. Cryst. Growth, vol. 138, 219-224

(1994).

Carlson. F.M., and Moosbrugger, J.C. "The role of thermal stress in vertical Bridgman growth of CdZnTe crystals." MAE

Department Seminar Series, Clarkson University. Potsdam. NY. September. 1994.

Carlson, F.M., Lee, T., Larson. Jr., D.J., Long, G., and Dudley, M. "CdZnTe crystal growth predictive modeling and

characterization." Gordon Research Conference on Crystal Growth. Andover, NH, July, 1994.

Carlson, F.M., Moosbrugger, J.C., Lee, T., and Larson, Jr., D.J. "CdZnTe crystal growth: predicitve modeling." ARPA

Intelligent Processing of Materials Workshop, Arlington, VA, November 12. 1993.

Casagrande, L.G., Larson, Jr., D.J., DiMarzio, D., Wu. J., and Dudley, M. "Growth of large-area, high quality. CdZnTe

substrates by the computer controlled vertical Bridgman method." SPIE Meeting on Producibility of II-VI Materials and

Devices, Orlando, FL, April 5-8, 1994.

Casagrande, L.G., Larson. Jr.m D.J., DiMarzio, D., Wu, J., and Dudley, M. "Growth of large-area, high quality, CdZnTe

substrates by the computer controlled vertical Bridgman method." SPIE Proceedings 2228: Producibility of II-VI

Materials and Devices, H.K. Pollehn and R. Balcerak. eds., 21-32, 1994.

Casagrande, L.G.. Larson. Jr., D.J., DiMarzio. D.. Wu, J., and Dudley, M. The growth and comparison of large-diameter,

vertical Bridgman CdZnTe and CdTe. J. Cryst. Growth, vol. 137, 195-200 (1994).

Chen, K.T., George, M.A., Zhang. Y., Burger. A., Su, C.H., Sha. Y.G., Gillies, D.C., and Lehoczkyt S.L. "Selenium

precipitation in ZnTe crystals grown by the physical vapor transport." American Physical Society Meeting March,

Pittsburg, PA. March 21-25, 1994.

Cheney, A.B.m and Andrews, J.B. "The evaluation of ampule materials for low-g processing of immiscible alloys."

Proceedings of the 6th International Conference on Experimental Methods for Microgravity Materials Science, TMS,

R.S.Schiffman and J.B. Andrews, eds.,191-197 (1994).

Cheyney, A.B. and Andrews. J.B. "The evaluation of ampule materials for low-g processing of immiscible alloys." TMS

Annual Meeting, San Francisco, CA, February 27-March 3, 1994.

DiMarzio, D., Larson, Jr., D.J., Casagrande, L.G., Silberstein, R.P., Wu. J., Dudley, M.. and Liao, P.-K. "Defect mapping

of CdZnTe substa'ates." IRIA-IRIS Proceedings: 1993 Meeting of the IRIS Specialty Group on Infrared Materials, 69-84.

December. L993.

DiMarzio, D., Larson, Jr., D.J.. Casagrande, L.G.. Wu. J.. Dudley, M., Tobin, S.. and Norton, P. "Large area X-ray

topographic screening of II-VI substrates and epilayers." SPIE Meeting on Producibility of II-VI Materials and Devices,

Orlando, FL, April 5-8. 1994.

DiMarzio, D., Larson. Jr., D.J., Casagrande, Wu, J.. Dudley, M.. Tobin, S., and Norton, P. "Large area X-ray topographic

screening of II-VI substrates and epilayers." SPIE Proceedings 2228: Producibility of II-VI Materials and Devices, H.K.

Pollehn and R. Balcerak, eds.. 5289-5300, 1994.

Dudley, M., Wu, J., Larson, Jr.. D.J., and DiMarzio, D. "Use of synchrotron white beam topography to characterize IR

detector manufacturing processes." Fall Meeting of the Materials Research Society, Boston, MA. November 29-December

3, 1993.

Dudley, M., Wu, J., Larson, Jr., D.J., and DiMarzio, D. "Use of synchrotron white beam topography to characterize IR

detector manufacturing processing." Material Research Society Symposium Proceedings 324: Diagnostic Techniques for

Semiconductor Materials Processing, O.J. Glembocki, F.H. Pollak, S.W. Pang, G. Larrabee, and G.M. Crean, eds.,

457-462, 1994.

|__||*____**n_!!||*|||*|N_!_*n___!|_!|_*_|__|___**|__*!___*!|*__*___!__!|!!_!!___!_!!__!_____!__*|!__||||*_|*||_|||!|_||!!__!*__*_!_|__|!!__||__|||||!_|*____!|!|______*!__!__!_|_!!!!!!!!!!_!__!_|!__!!|!_|n_|__|*_|___*__*|!_*_*_!*__*!|*_M*n

111-666
III. MSAD Program Tasks -- FY1994 Bibliographic Citations

Fedoseyev, A., Alexander, J.I.D., and Bessonov, O. "CNSPACK - Efficient solution of large sparse linear systems." First

Southeastern Linear Algebra Conference. Chattanooga, TN, May 27-28. 1994.

Fedoseyev, A,, and Alexander. LID. "Numerical modelling of solidification under microgravity conditions."

International Aerospace Ctmgress [AC '94, Moscow. August 15-19, 1994,

Fripp, A.L., Debnam, W.J., Crouch, R.K., and Clark, I.O, "Compound semiconductor growth in a low-g environment."

Microgravity Materials Science Conference. Huntsville. AL, May 24-25. 1994.

Fripp, A.L., Debnam, W.J., Szofran. F.R.. amd Chait. A. "Melt stabilization of PbSnTe in a magnetic field."

Microgravity Materials Science Conference, Huntsville. AL, May 24-25, 1994.

Gadonniex. D., Gokhale, A., amd Abbaschian, R. "Morphological stability of faceted solid/liquid interfaces in dilute

Bi-Sn alloys." Proceedings of the 32nd Aerospace Science Meeting, AIAA 94-0791. January, 1994.

Glicksman, M.E. "Dendritic growth in microgravity: IDGE flight 1," Aachen Foundry Institute, Aachen, FRG. 1994.

Glicksman, M.E. "Dendritic growth in microgravity: IDGE flight 1." DLR, Space Simulation Institute. Koln-Portz, FRG,

1994.

Glicksman, M.E. "The isothermal dendritic growth experiment: First results from USMP-2." Pittsburgh Chapter of the

ACCG, Pittsburgh. PA, 1994.

Glicksmano M.E. "The isoothermal dendritic growth experiment: First results from USMP-2." Microgravity Materials

Science Conference, Von Braun Civic Center. Huntsville, AL. 1994.

Glicksman, M.E. "Space flight data from the isothermal dendritic growth experiment." At the 26th COSPAR, Hamburg,

FDR, 1994.

Glicksman, M.E. "Space flight data from the isothermal dendritic growth experiment." Giesserei Institut, RWTH Aachen.

Aachen, FRG, 1994.

Glicksman, M.E. "The isothermal dendritic growth experiment: Implications of Theory." NIST, Gaitherburg, MD, 1994.

Glicksmau, M.E "Space flight data from the isothermal dendritic growth experiment: What have we learned'?." Materials

Engineering Department Seminar, Rennselaer Polytechnic Institute, Troy, NY. 1994.

Glicksman. M.E., Koss, M.B. and Winsa, E.A. Dendritic growth velocities in microgravity. PhysRev.l,ett. 73(4), 573

(1994).

Glicksman, M.E., Koss, M.B., Bushnell, L.T., LaCombe, J.C.. and Winsa, E.A. "Space flight data from the isothermal

dendritic growth experiment." COSPAR '94 (in press) 1994,

Glicksman, M.E., Koss, M.B., Bushnell, L.T.. LaCombe, J.C., Kobryn, P., and Winsa. EA. "The telle-operational

capabilities of the IDGE." 6th International Symposium on Experimental Methods of Microgravity Science, edited by

R.A. Schiffman and J.B. Andrews. The Minerals, Metals & Materials Society, 141, 1994.

Gobba, W.A., Patterson, J.D., and Lehoczky, S.L. A comparison between electron mobilities in Hgl-xZnxTe and

Hgl-xCdxTe. Infrared Phys., vol. 34(3), 311 (1993).

Grugel, R.N. Microstructural evolution of primary dendrite trunks in directionatly solidified, hypoeutectic,

aluminum-silicon alloys. Metallurgical Transactions A., (In press).

Grugel, R.N "Appreciating gravity during directional solidification of metals and alloys." University of Missouri-Rolla,

April 20, 1994.

i ii i i I 1o I II I 1oIII I I III I I o I I I I ii I i I III I ii i ii I i I I i I i I I I i iI i i I I i I I I i i i e i Ii I I I I I I I i i I II I I i e i i i i i I I ii i ii I i o i ii i i I I i iI o I i i i l a i i i ii iI ii i ii I I I I II III I I I i I i i i i i ii i I II I I I I Oil I I I I I l I I I I II I i i a i i ii i i i i i I I I I I II I I i i i i i i i i i i ii Ii o I I I I I I Iii ii i ii i i i l ii i ill Ill I I I I I

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III. MSAD Program Tasks --FY1994 Bibliographic Citations

Grugel, R.N. and Fay Hua. "Using transparent materials to simulate soldification phenomena in metals - Microstructural

development in undercooled alloys." 8th Annual Alabama Materials Research Conference, 26-27 September 1994,

Tuscaloosa, AL.

Grugel, R.N. and Fay Hua "Evaluation of microstructurat development in undercooled alloys." Microgravity Materials

Science Conference, June 24-25, 1994, Huntsville, AL.

Grugel, R.N., Fay Hua, and T.G. Wang. Evaluation of the NaNO3 - Ba(NO3)2 eutectic system for use in investigating

solidification phenomena. Journal of Materials Science Letters., (In press).

Hayes, L.J., and Andrews, J.B. Proceedings of the 6th International Conference on Experimental Methods for

Microgravity Materials Science. TMS, R.S. Schiffman and J.B. Andrews, eds., 167-174 (1994).

Hayes, L.J., and Andrews, J.B. "The influence of convection on coupled growth in Al-ln hypermonotectic alloys." TMS

Annual Meeting, San Francisco, CA, February 27-March 3, 1994.

Heaney, D.F. and German, R.M. "New grain growth concepts in liquid phase sintering," in "Advances in Powder

Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton, NJ, vol. 3, pp 303-310, 1994.

Heaney, D.F., German, R.M., and Ahn, I.S. "The gravity effect on critical volume fraction in liquid phase sintering," in

"Advances in Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton, NJ, vol. 2, pp

169-180, 1993.

Heaney, D.F., R. M. German and I. S. Ahn, "The gravity effect on critical volume fraction in liquid phase sintering,"

Advances in Powder Metallurgy and Particulate Materials, vol. 2." Metal Powder Industries Federation, Princeton, NJ,

1993.

Hua, F. and R.N. Grugel. "Microstructural evolution in undercooled Pb - Sn alloys: Composition and sample size effects."

Experimental Methods for Microgravity Materials Science: 6th International Symposium, 1994, TMS, eds.. R.A.

Schiffman and J.B. Andrews, pp. 111-115.

Hua, F. and R.N. Grugel. "Microstructural evolution in undercooled Pb - Sn alloys: Composition and sample size effects."

123rd TMS Annual Meeting, February 27 - March 3, 1994, San Francisco, CA.

Hua, F. and R.N. Grugel. "Microstructural development in undercooled alloys." TMS Fall Meeting, October 17-21, 1993,

Pittsburgh, PA.

Hua, F., R.N. Grugel, and T.G. Wang. "Analysis of microstructural development during solidification in bulk, undercooled

Pb - Sn alloys." ASM-TMS Fall Meeting, October 2-6. 1994, Rosemont, IL.

Iacocca, R.G. and German, R.M. "Experimental Design for liquid phase sintering in microgravity." in "Advances in

Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton, N J, vol. 2, pp 181-194,

1993.

Iacocca, R.O. and R. M. German, "Experimental design for liquid phase sintering in microgravity," Advances in powder

metallurgy and particulate materials, vol. 2." Metal Powder Industries Federation, Princeton, NJ, 1993.

Iacocca, R.G., German, R.M., and Kidd, C. "Mierostructural analysis of tungsten heavy alloy samples sintered in 1-G

conditions: Preparation for shuttle flight," in "Advances in Powder Metallurgy and Particulate Materials." Metal Powder

Industries Federation, Princeton, NJ, vol. 5, pp 201-218, 1994.

Klein, J., and Larson, Jr., D.J. "Comparison of theoretical and experimental performance of a PMZF furnace for

microgravity materials processing." Symposium on l.tg Solidification: Theory and Experimental Results. TMS Meeting,

Pittsburg, PA, October 1993..

oii ill iOilOii illleOi ill iiillOiiiiIii iii ioi ill iilili oil ell ii i i ii Ill IlOla Ill Iii iiilila iiii ill ill Oil iIII ill Oil oIll Ill I Ol I lU III Ill o Ill III Ill I oI III IlI IeI oIll III Iou ell Ii i i i i ii i io i ili OOiliilJOi ill ii Oil o ill ill i io ill Oil Ill ill lie iiOilOelOlli iioiiill ill ii

111-6 6 8
Klein, J., and Larson, Jr., D.J. "Evaluation of solidification process control using a programmable multizone furnace

designed for microgravity materials processing." AIAA Space Programs and Technologies Conference and Exhibit.

Huntsville. AL, September 27-29, 1994.

Korpela, S.A., Chait, A.. and Matthiesen, D.H. Laterial or radial segregation in solidification of binary alloy with a curved

liquid-solid interface. J. Cryst. Growth, vol. 137, 623 (1994).

Koss, M.B. "Preliminary results from the isothermal dendritic growth experiment ." At the Space Experiments Division

Awards Ceremony, NASA Lewis Research Center, Cleveland, OH, 1994.

LaCombe, J.C. "Dendritic Solidification in a Microgravity Environment." Joint meeting of the Eastern New York Chapter

of ASM International and the Hudson-Mohawk Section of TMS. Latham, NY. 1994.

Larroude. P., Ouazzani, J., and Alexander, J.I.D. Symmetry-breaking flow transitions and oscillatory flows in a 2D

directional solidification model. European Journal of Mechanics B/Fluids, vol. 13, 353-381 (1994).

Larson, Jr., D.J. "Orbital processing of Zn-alloyed CdTe." 44th International Astronautical Congress, Graz. Austria,

October 16-22, 1993.

Larson, Jr., D.J. "Seeded CdZnTe vertical bridgman crystal growth and process model validation." Department of

Materials Science and Engineering Seminar, State University of New York at Stony Brook. March 23, 1994.

Larson, Jr., D.J., Alexander, J.I.D., Gillies, D., Carlson, F.M.. Dudley, M. "Orbital processing of high-quality cadmium

telluride compound semiconductors." NASA Microgravity Materials Science Conference, Huntsville, AL, May 25-26,

1994.

Larson, Jr., D.J., Alexander, J.I.D., Gillies, D., Carlson, F.M., Wu, J., and Black, D. "Orbital processing of high-quality

CdTE compound semiconductors." Proceedings of the Joint Launch + One Year Science Review of USML-1 and USMP-I

with the Microgravity Measurement Group. NASA Conference Publication 3272, vol. 1, 129-162, 1994.

Larson, Jr., D.J., DiMarzio, D., Casagrande, L.G.. Carlson, E.M., Lee, T., Steiner, B., Long, G., Seiler, D.G., Wu, J., and

Dudley, M. "Producibility improvements suggested by a validated process model of seeded CdZnTe vertical Bridgman

growth." SPIE Meeting on Producibility of II-VI Materials and Devices, Orlando. FL, April 5-8, 1994.

Larson,

Dudley,

growth.

Jr., D.J.. DiMarzio, D., Casagrande, L.G., Carlson. F.M.. Lee, T., Steiner, B.. Long, G.. Seiler, D.G., Wu, J., and

M. Producibility irnprovemtns suggested by a validated process model of seeded CdZnTe vertical Bridgman

J. Cryst. Growth, vol. 137, l 1-20 (1994).

Larson, Jr., D.J., Silberstein, R.P., DiMarzio, D., Carlson, F.M., Gillies, D., Long, G.. Dudley, M., and Wu, J.

Compositional, strain contour, and property mapping on CdZnTe boules and wafers. Semiconductor Science and

Technology, vol. 8, 911-915 (1993).

Lee, D., Uffelman, D., and Johnson, W. "Noncontact AC calorimetry of metals and alloys." Proceedings of NATO

Workshop on Science and Technology of Rapid Solidification, West Point, NY (1994).

Lehoczky, S.L., Szofran, F.R., Gillies, D.C., Cobb. S.D., Su, C.-H., Sha, Y.-G., and Andrews, R.N. "Crystal growth of

selected II-VI semiconducting alloys by directional solidification." Proceedings of the Joint Launch + one Year Science

Review of USML-I and USMP-I with the Microgravity Measurement Group, N. Ramachandran, D.O. Frazier, S.L.

Lehoczky, and C.R. Baugher, eds., NASA Conference Publication 3272, vol. 1, 163 (1994).

Majewski, J.A., and Matthiesen, D.H. Quantitative infrared imaging for the measurement of dopant distribution in gallium

arsenide. J. Cryst. Growth, vol. 137, 249 (1994).

Matthiesen, D.H. The total pressure of arsenic over molten gallium arsenide at 1260 °C. J. Cryst. Growth, vol. 137, 255

(1994).

I i IIl el I Ill loll I la III llll lea Ill llll lee Ill III lllllll III Ill lllllllllllllll Ill Ill Ill Ill el I I II Ill Ill lII III ll I II I II I III l Ill Illlll III II I llll IIIIII III Otto Ill I I I I II I II III llll III l I I I It I l III I I l I I l III l I Il I I l Ill I el l II II I II I l Illll l Ill Ill III llll Ill Ill l III ll I

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Matthiesen. D.H. "The study of dopant segregation behavior during the growth of GaAs in microgravity." Proceedings of

the Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group. NASA

Conference Publication 3272. 223-259 (1994).

Moosbrugger, J.C., and Levy. A. "Constitutive modeling for CdTe single crystals." Seminar on Microgravity

Solidification: Theory and Experimental Results. TMS Materials Week '93. Pittsburg. PA. October L8. 1993.

Moosbrugger, J.C., and Levy. A. "Advanced constitutive modeling for CdTe single crystals." Poster presented at the

Gordon Research Conference on Crystal Growth, Andover. NH. July, 1994.

Moosbrugger, J.C., Levy, A.. and Carlson. F.M. "Constitutive modeling for CdTe single crystals." ARPA Intelligent

Processing of Materials Workshop, Arlington, VA. November 12, 1993.

Morton, C.W., Hofmeister, W.H., Bayuzick. R.J., and Robinson, M.B. A statistical approach to understanding nucleation

phenomena. Materials Science and Engineering, vol. A178, 209-215 (1994).

Palosz. W., and Wiedemeier, H. Residual gas pressures in sealed fused silica glass ampoules. J. Cryst. Growth. vol. 131,

193 (1993).

Palosz, W.. Szofran, F.R., and Lehoczky, S.L. The effect of heat treatment in the magnitude and composition of residual

gas in sealed silica glass ampoules. J. Crys. Growth, vol. 142, 215-224 (1994).

Palosz, W., Szofran, F.R., and Lehoczky, S.L. The effect of heat treatment in the magnitude and composition of residual

gas in silica glass ampoules. J. Cryst. Growth. vol. 142. 215-224 (1994).

Pang, H., and Stefanescu, D.M. "Influence of Interface Morphology on the Pushing/Engulment Transition of Polystyrene

Particles in Succinonitrile + Water Systems" in "Experimental Methods for Microgravity Materials Science Research."

Edited by: R.A. Schiffman and B. Andrews TMS/Warrendale, PA, pp 209-213, 1994.

Pang, H.T., Stefanescu, D.M., and Dhindaw, B.K. "Influence of interface morphology on the pushing/engulfment

transition of polystyrene particles in succinonitrile + water matrices." Cast Metal Matrix Composites, Proceedings of the

2rid International Conference, D.M. Stefanescu and S. Sen, eds., AFX, Des Plaines, IL, 57-69 (1993).

Raman, R., Heaney, D., and German, R.M. "Control of component distortion during liquid phase sintering," in "Advances

in Powder Metallurgy and Particulate Materials." Metal Powder Industries Federation, Princeton. NJ, vol. 3. pp 281-293,

1994.

Rogers, M.J.B., Wolf, R.P., and Alexander, J.I.D. "Correlation of accelerometer data on STS-50 (USML-1)." Proceedings

of the Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group, NASA

Conference Publication 3272, vol. 2, 893-906, 1994.

Rosch, W., Fripp, A., Debnam, W., and Pendergrass, T.K. Heat transfer measurements in the Bridgman configuration. J.

Crystal Growth, vol. 137, p. 54 (1994).

Ruggeri, R.T., Shepherd, W.B., Bowman, D.R., Bohnhoff-Hlavacek, G., Willenberg, H., Su, C.H.. Szofran. F.R., Rubart,

W.S., and Stoebe, T.G. "The crystals by vapor transport experiment (CVTE): space processing and preliminary results."

44th International Astronautic Congress of the International Astronautic Federation, Graz, Austria, October 16-22, 1993.

Schwartz, E. and Szekely, J. "Some perspectives on electromagnetic levitation in space experiments." Proceedings of

Electromagnetic Processing of Materials, The Iron and Steel Institute of Japan, Nagoya, Japan, 1994.

Schwartz, E. and Szekely, J. "The shape of liquid metal droplets in electromagnetic levitation experiments considering

internal fluid flow." Proceedings of Experimental Methods for Microgravity Materials Science, 1994 TMS Annual

Meeting, San Francisco, CA, 1994, 73-79.

Sha, Y.G, Su, C.H., and Szofran, F.R. Thermodynamic analysis and mass flux of the HgZnTe-HgI 2 chemical vapor

transport system. J. Cryst. Growth, vol. 131, 574-588 (1993).

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Ill--670
Sha.Y.G.,Su,C.H.,Palosz. W..Votz.M.P.,Gillies,D.C.,Szofran, F.R..Lchoczky, S.L.,Liu,H.C.,andBrebrick. R.F.

"Masstluxandcrystal growthofZnSebyPVT."8thInternational Conference onVapourGrowthandEpitaxyIICVGE-8).

Freiburg, Germany. July24-29.1994.

Singh,N.B.,Stewart. A.M.,Hamacher. R.D..Mazelsky, R.,Duval.W.M.B.,Santoro. G.J.,DeWitt,R.andLehoczky. S.L.

Convecto-diffusive growthofleadbromidecrystals: atestof theories.J.Cryst.Growth.139.158-164(1994).

Smith,R.N.,Glicksman, M.E.,Koss,M.B.,Bushnell. LT..andLaCombe, J.C."Experimental studyofdendritegrowthin

anundercooled meltundermicrogravity conditions." HeatTransfer sessionatthe1994ASMEWinterAnnual Meeting in

Chicago next November (in press) I994.

Sorokach, S.E., Simchick. R.T., Fripp, A.L.. Debnam. W.J.. and Barber, P.G. "Characterization of Bridgman crystal

growth using radiographic imaging," in "'Grain Boundaries and Interface Phenomena in Electronic Ceramics." Edited by:

LM. Levinson and S-I. Hirano The American Ceranuc Society, Ohio. pp 379, 1994.

Su, C.H., Sha, Y.G., Volz, M.P., Gillies. D.C.. Lehoczky, S.L., Zhou. W., Dudley, M.. Liu. H.C., Brebrick, R.F., and

Wang, J.C. "Ground based research on the growth of II-VI compound semiconductors by physical vapor transport."

Proceedings of the 8th Annual Symposium on Micro_ravity Science and Space Processing, AIAA 32nd Aerospace Sciences

Meeting, paper no. 94-0564 (1994).

Su, C.H., Sha, Y.G., Volz, M.P.. Gillies. D.C., Szofran, FR.. Lehoczky. S.L.. Zhou. W.. Dudley, M., Liu. H.C.. Brebrick,

R.F., and Wang, J.C. "Ground based research on the growth of II-VI semiconductors by physical vapor transport." AIAA

32nd Aerospace Sciences Meeting, 8th Annual Symposium on Microgravity Science and Space Processing, Rend. NV,

Janaury 10-13, 1994.

Su, C.H., Volz, M.P., Gillies, D.C., Szofran, F.R., Lehoczky, S.L., Dudley, M., Yao, G.D., and Zhou, W. Growth of ZnTe

by physical vapor transport and traveling heater method. J. Cryst. Growth, vol. 128, 627-632 (1993).

Su, C.-H., Volz, M.P., Gillies. D.C., Szofran, F.R., Lehoczky, S.L., Dudley, M., Yao. G.-D.. and Zhou. W. Growth of

ZnTe by physical vapor transport and traveling heater method. J. Cryst. Growth, vol. 128, 627-632 (1993).

Wiedemeier, H. "Vapor growth of Hg_ _Cd_Te epitaxial layers on (100)CdTe substrates under normal and reduced gravity

conditions." 8th International Conference on Vapor Growth and Epitaxy, Stuttgart, Germany.

WiedemeierQ H. "Vapor growth of Hg_._Cd_Te epitaxial layers on (100)CdTe substrates under normal and reduced gravity

conditions." Max-Planck-Institute, Stuttgart, Germany.

Wiedemeier. H. "Vapor growth of Hg_._C_Te epitaxial layers on (100)CdTe substrates under normal and reduced gravity

conditions." Solid State Research Symposium, University of Munster. Munster, Germany.

Wiedemeier, H., and Wu, G.H. Fast vapor growth of cadmium telluride single crystals. J. Electronic Materials, vol. 22,

1121 (1993).

Wiedemeier, H., and Wu, G.H. Fast growth of Cd_._Zn_Te single crystals by physical vapor transport. J. Electronic

Materials, vol. 22, 1369 (1993).

Zhou, W., Wu, J., Dudley, M., Su, C.H., Volzi M.P., Gillies, D.C., Szofran, F.R., and Lehoczky, S.L. "Characterization of

growth defects in ZnTe single crystals." Materials Research Society Proceedings, Infrared Detectors - Materials.

Processing, and Devices, A. Applebaum and L.R, Dawson, eds., 299 (1993).

Ground: Benchmark Science

Ahlers, G. "Dynamics of the superfluid transition of 4He." Proceedings of the NASA/JPL 1994 Microgravity Low

Temperature Physics Workshop.
III. MSAD Program Tasks--FY1994 Bibliographic Citations

Barmatz. M.. and Hahn. 1. "Microgravity test of universality and scaling theory predictions near the liquid-gas critical

point of 3He." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop..

Bauer, G.. Donnelly, R.J., and Vinen, W.F "Vortex configurations in a freely rotating superfluid drop." Proceedings of the

NASAkJPL 1994 Microgravity Low Temperature Physics Workshop.

Campbell, C. E. Remnants of bose condensation and off-diagonal long range order in finite systems. J. Low Temp Phys.,

Vol 93, 907 (1993).

Campbell, C.E. "Recent developments in liquid helium-four ." Eighth International Conference on Recent Progress in

Many Body Theories, August 1994.

Chui, T.C.P, and Israelsson, U.E. "Heat capacity under pressure oscillations- a proposal to measure the order-parameter

relaxation time in space." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Chui, T.C.P, Day, P., Hahn, I., Nash, A.E., Swanson, DR., Nissen. J.A., Williamson, P.R., and Lipa, J.A. "High

resolution thermometers for ground and space applications." Proceedings of the 15th International Cryogenic

Engineering Conference, Genova Italy 1994.

Day, P., Chui, T., and Israelsson, U. "Heat capacity of helium under superfluid flow conditions." Proceedings of the

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Donnelly, R.J. "Superfluid Drops: An Overview." Proceedings of the NASA\JPL 1994 Microgravily Low Temperature

Physics Workshop.

Elbaum, C., and Kosterlitz, J.M. "Kinetic and thermodynamic studies of melting-freezing of helium in microgravity."

Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Giese, C. '1A novel approach to the observation of the condensate fraction in superfluid helium-four?' Eighth AIAA

Symposium on Microgravity Science, Reno, Nevada. January 10-13, 1994.

Hahn, I., and Barmatz. M. "Application of GdCI3 thermometry at temperatures near the liquid gas critical point of 3He."

Proceedings of the NASA JPL 1994 Microgravity Low Temperature Physics Workshop.

Halley, J.W. Structure of the condensate and some possible ways to observe it.. J. Low Temp. Phys., Vol. 93, 893

(1993).

Halley, J. W. A novel approach to the observation of the condensate fraction in superfluid helium-four. Physica. Vol B97,

175 (1994).

Halley, J.W. "Formulations of the many body atom-droplet scattering problem." Workshop on Future Directions of

Quantum Many Body Theory, January 14-16, 1994.

Halley, J.W. "Looking for new experimental manifestations of long range quantum coherence in superfluid helium-4?'

Physics Colloquium, North Dakota State University, Fargo, ND, February 21 1994.

Halley, J.W. "Looking for long range quantum coherence in superfluid helium." Physics Seminar at St. Olaf College,

Northfieldt MN, March 23, 1994.

Halley, J.W. "Evaluating experimental ideas for observing long range quantum coherence in superfluid helium." Invited

talk at the American Physical Society Washington meeting, April 19, 1994.

Halley, J.W. "Looking for long range quantum coherence in superfluid helium." Condensed Matter Theory Seminar, Ohio

State University1 Columbus, OH, April 18, 1994.

Halley, J.W. "Evaluating experimental ideas for observing long range quantum coherence in superfluid helium."

Workshop on Quantum Fluid Clusters, Ringberg, Schloss, Kreuth-Oberhof, Bavaria, June 12-15, 1994.

lllllll Ill lO|l|le el! ll|l III llllll I| |l|l nll i i! I II IIiii i Iiiii i I ell|l II! IIIIII l|l lli leo I ! I II I III llll I|! III Ill III l I! If|If|! I|! I| I III I ! l III l II I I ! I I I f I I I I I I II I I I f I | ! II ill I I li*ll ! | II I I! I|! I |l I II I I I I !I I I ! I ! ! I I I I I! II I I I I I I II lill I ! I I II! tli! II I II t I I l!ll 0

Ill-672
III. MSAD Program Tasks--FY1994 Bibliographic Citations

Iol.*no0nooal|aliln011HaO* .olnoloolaooloouaaot .ll0nl0un.u.lllllola.aolaoH.n.a. Jnonooa.uo .oaooaoolnola.aool.llola.llooJ.l.laooonollanaoo.olnoo.|oaolo. o o.olloo.olaoaaooooo.o.oluolaoaaoo .o .ol.loo H oluolaolooJloo. OOlOOl

Howald, C.. Qin, X., Nham, H.S., and Meyer. H. Shear viscosity measurements of liquid 4He and 3He-4He mixtures near

the tricritical point. J. Low Temp. Phys.. vol 86. (1994).

Israelsson. U.E.. Strayer, D.M.. Chui. T.C.P., Larson. M., and Duncan. R.V. Dynamic measurements near the

lambda-point in a low-gravity simulator on the ground. Physica B. vol 194-196. 593-594 (1994).

J. W. Halley "Theoretical studies of manifestations of long range quantum coherence in 'He in atom-droplet interactions."

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

J. W. Halley "Ground based experiments to observe long range quantum coherence in superfluid 4He using atomic beams."

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Larson. M.. and Israelsson. U.E. "Simulations of the lambda transition of Helium-4 with an applied heat flow for Ig and

reduced gravity environments." 1994 March meeting of the American Physical Society.

Larson. M., and lsraelsson, U.E. "The lambda point in a low-g simulator - progress report." The 1994 Microgravity Low

Temperature Physics Workshop, Washington D.C., January, 1994.

Liu, F.C., and Ahlers, G. "The effect of a finite heat current on the lambda-transition and on the thermal conductivity of

4He." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Manousakis. E. "Numerical simulation of scaling in superfluid films." Proceedings of the NASA/JPL 1994 Microgravity

Low Temperature Physics Workshop.

Manousakis, E. "Numerical simulation of scaling in superfluid films." 1994 Microgravity Low Temperature Physics

Workshop, Washington, D.C. January 18-21, 1994.

Niemela, J.J., and Donnelly, R.J. "Density and dielectric constant measurements in liquid helium." The Proceedinds of the

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Rudnick, J., and Barmatz, M. "Effects of random motions on critical point measurements." Proceedings of the NASA/JPL

1994 Microgravity Low Temperature Physics Workshop.

Schultka, N. "Finite-scaling of the superfluid density in two dimensions and thin films." Max Planck Institut fur Physik,

Munich, Germany, December 1993.

Schultka, N. "Finite-scaling of the superfluid density in two dimensions and thin films." Institut fur Theoretische Physik.

RWTH Aachen, Aachen, Germany, December 1993.

Schultka, N. "Finite-scaling of the superfluid density in two dimensions and thin films." Institut fur Kernphysik, TU

Wien, Vienna, Austria, December 1993.

Schultka, N., and Manousakis E. "Finite-size scaling of the superfluid density in two-dimensional superfluids."

Proceedings of the 20th International Conference on Low Temperature Physics.

Scbultka, N., and Manousakis E. Finite-size sealing in two-dimensional superfluids. Phys. Rev. B, vol 49. 12071 (1994).

Schultka, N., and Manousakis, E. Crossover from two-dimensional to three-dimensional behavior in superfluids. Phys.

Rev. B, (submitted).

Sehultka, N., and Manousakis, E. Finite-size scaling of the specific of superfluids. Phys. Rev. B, (submitted).

Schultka, N., and Manousakis, E. Crossover from two-dimensional to three-dimensional behavior in superfluids-boundary

effects. Phys. Rev. B., (submitted).

Schultka, N., and Manousakis, E. "Crossover from two to three dimensions in superfluid films." APS Meeting, Pittsburgh

PA, March 1994.

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111-6 7 3
III. MSADProgramTasks-- FY1994 Bibliographic Citations

Schultka, N,. and Manousakis. E. "Finite size scaling in two-dimensional superfluids." APS Meeting, Pittsburgh PA,

March 1994.

Tonucci. R.J., Chui, T.C.P_ Israelsson. J.A. and Lipa. J,A.. "Application of nanochannel array for the studies of finite

size effects near a second order phase transition/' Proceedings ot the NASA/JPL 1994 Microgravity Low Temperature

Physics Workshop.

Weilert, M.A., Whitaker, D.L., /vlaris, H.J.. and Seidel, G.M. "Optical and magnetic levitation of superfluid helium

drops." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Williams. M. "Ground based experiments on quantum coherence in helium-four." NASA Graduate Student Researchers

Program 1994 Annual Symposium. Washington, DC. May 11-13, 1994.

Yeh, N.C., Strayer. D.M., Chui, T.C.P., and Lysek, M.J. "Exploring the helium lambda transition using a high-Q

microwave cavity." Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Zhong, F., and H. Meyer, H. "Density equilibration near the liquid-vapor critical point in 3He." Fluid Mechanics

Phenomena in Microgravity, American Society of Mechanical Engineers.

Zhong, F., and Meyer, H. "Densisty equilibration near the liquid-vapor critical point in 3He." Proceedings of the

NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Zhong, F., and Meyer, H. "Numerical calculation of density equilibration above the 3He liquid-vapor critical point."

Proceedings of the NASA/JPL 1994 Microgravity Low Temperature Physics Workshop.

Zhong, F. and Meyer, H. "Density equilibration for a pure fluid near Tc: Application to 3He." Proceedings of the 12th

Symposium on Thermophysical Properties.

Zhong, F., and Meyer, H. Density equilibration near the liquid-vapor critical point of a pure fluid: I-single phase T>Tc.

Phys Rev B, (submitted).

Ground: Biotechnology

Akins, R.E. "Neonatal rat heart cells cultured in simulated microgravity." Gordon Research Conference: Gravitational

Effects on Living Systems, August 1994.

Akins, R.E. Schroedl, N.A. Gonda, S.R. and Hartzell. C.R. Neonatal rat heart cells cultured in simulated microgravity. In

Vitro Cell Diff.. (Submitted 8/94).

Akins, R.E., Schroedl, N.A. Gonda, S.R. and Hartzell, C.R. "Characterization of a novel three-dimensional culture system

for cardiac cells." Mol. Biol. Cell., American Society for Cell Biology's 34th Annum Meeting, San Francisco, CA.

December 1994.

Anderson, S.M., Becker, J.L., Papenhausen, P.R. "Verification of an i(5p) marker chromosome in a mixed mullerian tumor

of the ovary by fluorescence in situ hybridization." Internatl. Conf. Immunogenet, 1994.

Becker, J.L. Women's health issues and space based medical technologies. Earth Space Review, 3, 15-19 (1994).

Becker, J.L. Microgravity model of ovarian tumor cell growth. Low G, 5, 12 (1994).

Becker, J.L., Goodwin, T.J.. Prewett, T.L., and Spaulding, G.F. "Growth and gene expression in human ovarian cancer."

Workshop on Cell Culture Applications in Biotechnology, World Cong. Cell Tiss. Culture, 1994.

Carter, D.C., and Ho, J.X. Structure of albumin. Advances in Protein Chemistry, vol. 45, 153-203 (1994).
lII. MSAD Program Tasks -- FY1994 Bibliographic Citations

Dai, W., Belt J. and Saltzman. W.M. Cell-binding peptides conjugated to poly(ethylene glycol) promote neural cell

aggregation. BiogFechnology, 12. 797-801 (1994).

Douglas, L.J.. Lupkowski, M.. Dodd. T.L.. and van Swol. F. On the role of solvation forces in colloidal phase transitions.

Langmuir. vol. 9, 1445 (1993).

Fredericks, W.J., Hammonds, M.C.. Howard, S.B., and Rosenberger, F. Density, thermal expansivity, viscosity and

refractive index of lysozyme solutions at crystal growth concentrations. J. Cryst. Growth, vol. 141, 183-192 (1994).

Freed. L.E. Grande, D.A. Lingbin, Z. Emmanual. J. Marquis J.C. Langer, R. Joint resurfacing using allograft chondrocytes

and synthetic biodegradable polymer scaffolds. J. Biomed. Mater. Res., 28, 891-899 (1994).

Freed, L.E. Marquis, J.C. Vanjak, G. Emmanual, J. Langer, R. Composition of cell-polymer cartilage implants. Biotech.

Biocng., 43, 605-614 (1994).

Freed, L.E. Vanjak, G. Biron, R.J.,Eagles, D. Lesnoy, D. Barlow, S.K. Langer R. Biogradable scaffolds for tissue

engineering. Bio/Technology, 12, 689-693 (1994).

Freed, L.E. Vanjak-Novakovic. G. Marquis, J.C. Langer, R. Kinetics of chondrocyte growth in cell-polymer implants.

Biotech. Bioeng., 43, 597-604 (1994).

Freed, L.E.,Vunjak-Novakoic, G. Blum. J.K. Emmanual, J. "Effects of shear on in vitro chondrogenesis." Tissue Culture

Association, Durham, NC (June 1994).

Freed, L.E. Vunjak-Novakovic, G. "Tissue engineering of cartilage". In: Brozinog J.D. (ed). The Biomedical Engineering

Handbook, CRC Press., (In press 1994).

Freed, L.E. Vunjak-Novakovic, G. Microgravity Tissue Engineering. In Vitro Cell. Dev. Biol., (Submitted 8/94).

Freed, L.E. Vunjak-Novakovic, G. Cultivation of cell-polymer implants in bioreactors. In: J.B. Griffiths. A. Doyle, D.G.

Newell (eds). Cell and Tissue Culture Laboratory Procedures, Wiley & Sons (invited chapter), (September 1994).

Freed, L.E. Vunjak-Novakovic, G. Cultivation of cell-polymer constructs in simulated microgravity. Biotech. Bioeng.,

(Submitted August 1994).

Freed, L.E.,Vunjak-Novakovic, G. "Chondrocytes cultured on biodegradable polymers form neocartilage in vitro and in

vivo." European Society for Osteoarthrology, Bari. Italy (September 1994).

Freed, L.E. Vunjak-Novakovic. G. "Tissue engineered cartilage: bioreactor cultivation and in vivo implantation."

Biomedical Engineering Society, Tempe, AZ (October 1994).

Freed, L.E. Vunjak-Novakovic, G. Grande. D.A. Emmanual, J. Langer, R. "Cell-Polymer Cartilage Implants." Keystone

Tissue Engineering Conference, Taos, NM (February 1994).

Frink, L.J.D., and van Swol. F. Solvation forces and colloidal stability: A combined Monte Carlo and density functional

theory approach. J. Chem. Phys., vol. 100. 9106 (1994).

Frink, L.J.D., Zamora, P., van Swol, F., and Zukoski, C.F. "The freezing of colloidal suspensions in confined systems."

8th International Conference on Surface and Colloid Science, Adelaide, Australia, February, 1994.

Galvan, D.L., Wankowski, D.M., Bacciao, Dillberger, A., Karmiol, S., Hammond, T.G. and Lelkes P.I. "Human renal

epithelial cells in culture differentiate under simulated microgravity." To be presented at the Annual ASCB Meeting, Dec.

1994.

George, A., and Wilson, W.W. Predicting protein crystallization from a dilute solution property. Acta Cryst., vol. D50,

361-365 (1994).

I|IIII llIOlll|l Of( lIll lIllllIIIIIIIl|O l|lII!lIIIII! IIIIIIIII*II !J|OOOOO|I!|IIIIIIOIIII,IIIIIlIIIIIIIIIIIII.II1111OIIIIIIIIIIIOIiOIlIOIIIIlIIIIII!!III!1111111111111111111.I!OIIIllIlIII,IOIIIIIIIIli IIOIOlll111111!IISIIIOlIOiOOiOOlIOI!IIIIIIIIIIIIIIIIIIII

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III. MSADProgramTasks-- FY1994 Bibliographic Citations

Gutsche. A.T.. Parsons-Wingerter P. Chand, D. Saltzman. W.M. and Leong K.W. N-acetylglucosamine and adenosine

derivatized surfaces for cell culture: 3T3 fibroblast and chicken hepatocyte response. Biotechnology and Bioengineering,

43, 801-809 (1994).

Ho, M.L., Molnar, G. Funanage. V.L. and Schroedl. N.A. "Myogenic gene expression during postnatal myogenesis."

Mol. Biol. Cell.. American Society for Cell Biology's 34th Annual Meeting, San Francisco, CA. December 1994.

Ho, M.L., Molnar, G. Funanage, V.L. Schroedl, N.A. Expression and quantitation of myogenic factors during postnatal

myogenesis. Dev. Biol., (Submitted 9/94).

Holshek. J.G. and Akins, RE. Acetonitrile: A superior dehydrating agent in cellular preparations for SEM. /Vlicroscopy

Research and Techniques, (Submitted 7/94).

Holshek. JG. and Akins, R.E. Acetronitrile is better than ethanol as a dehydrating agent for cells prepared for SEM. Proc.

Micros. Soc. Amer., 52, 324-325 (1994).

Ingram, M., Techy, G.B., Narayan, S., Saroufeem. R., Bishai, M.. Spaulding, G.F. and Goodwin, T.J. Epithelial

differentiation of early passage human bladder cancer cells in simulated microgravity of the NASA HARV bioreactor. (In

preparation).

Ingrain, M,, Techym, G.B., Narayan, S.. Saroufeen. R.. Spaulding. G.F., and Goodwin. T.J. Variable three-dimensional

growth of human malignant tumors in simulated microgravity _t the NASA HARV bioreactor. (In preparation).

Jessep, J.M. Goodwin, T.J. and Spaulding G. Prospects for use of microgravity-based bioreactor to study

three-dimensional host-tumor interactions in human neoplasia. J. Cell Biochem., 51. 290-300 (1993).

Jessup J., Goodwin T. "Simulated microgravity improves production of colonic growth factors." AIAA Space Programs

and Technologies Conference and Exhibit, September 21-23, 1993, Huntsville, AL. AIAA-93-4098.

Jessup, J. Goodwin T. "Simulated microgravity improves production of colonic growth factors." AIAA Space Programs

and Technologies Conference and Exhibit. September 21-23, 1993, Huntsville, AL. AIAA-93-4098.

Jessup, J.M. Brown K. Ishii S. Ford R. Goodwin TJ. Spaulding G.F. Simulated microgravity does not alter epithelial cell

adhesion to matrix and other molecules.. Adv. Space Res.. t4(8), 71-76 (1994).

Jessup, J.M. Brown K. Ishii S. Ford R. Goudwin T.J. Spaulding G.F. Simulated microgravity does not alter epithelial cell

adhesion to matrix and other molecules. Adv. Space Res., 14(8/. 71-76 (1994).

Jessup, J.M. Fitzgerald W, Polanec J. Ford R. Goodwin T. Spaulding G.E. Brown D. "CEA production in human colon

cancer." 1994 Meeting of the Tissue Culture Association, Research Triangle Park, NC. June, 1994.

Jessup, J.M. Fitzgerald W. Polanec J. Ford R. Goodwin T. Spaulding G.F. Brown D. "CEA production in human colon

cancer." 1994 Meeting of the Tissue Culture Association, Research Triangle Park, NC, June 1994.

Jessup, J.M. Goodwin T.J. and Spaulding G. Prospects for use of microgravity-based bioreactors to study

three-dimensional host-tumor interactions in human neoplasia. J. Cell. Biochem., 51, 290-300 (1993).

Jessup, J.M. Thomas P. Ford R.D. Ishii S. "Homotypic adhesion mediated by carcinoembryonic antigen (CEA) in

colorectal carcinoma cells involves CD44 and NCA." Keystone Symposium, Cell Surface and Tissue Engineering Meeting,

Taos, NM, February, 1994.

Jessup, J.M., Thomas P. Ford R.D. lshii S. "Homotypic adhesion mediated by carcinoembryonic antigen (CEA) in

colorectal carcinoma ceils involves CD44 and NCA." Keystone Symposium. Cell Surface and Tissue Engineering Meeting,

Taso, NM, February 1994.

Johnson, C.A., and Lenhoff, A.M. "An AFM study of latex particle adsorption on mica." ACS Colloid and Surface Science

Symposium, Stanford, CA, 1994.

i i i ii ii i it i i I i I I II I I II I I I lll I IiI i I I II ii i i IiI I II I u Iil i i i i i i i i i i ii i i i i i i i i iI I I i i i i I i III i IIII i n i i ii i I II I I III I I I II i i i i i i I i iI I i I llI I I I I II I II III I I I I I I I III I Ii I I I I I i I I i III I I I i I I III J I i, I i I, I I I I I I II II I I I I I I I III I I ¢I I I I I III III IIII I I i I J l I I I JJ I I I I III I II III

111-6 7 6
II|. MSADProgramTasks- FY1994 Bibliographic Citations

Johnson. C.A., Haggerty. L.. Wu, P., Lenhoff. A.M., and Wagner, N.J. "Ordered arrays of adsorbed prmeins: modelling

and observation by scanning probe microscopy." 8th International Conference on Surface and Colloid Sciences, Adelaide,

South Australia, February 13-18, 1994

Johnson. C.A., Wu. P., Lenhoff, A.M.. and Wagner, N.J. "Modelling of the formation _ff ordered protein arrays at

liquid-solid interfaces." AIChE Annual Meeting. St. Louis, MO, 1993.

Konnert, J.H., D'Antonio. P., and Ward. K.B. Observation of growth steps, spiral dislocations and molecular packing on

the surface of lysozyme crystals with the atomic force microscope. Acta Cryst., vol. D50, 603 613 t1994t.

Konnert, J.H., D'Antonio, P.. and Ward. K.B. Observing the growth of protein crystals. NRL Review. 130-132 {19941.

Krewson, C.E., Chung, S.O. Dai, W. and Saltzman. W.M. Cell aggregation and neurite growth in gels t_t extracellular

matrix molecules. Biotechnology and Bioengineering, 43, 555-562 (1994).

Lelkes, P.I., Ramos, E.M., Chick, D.M.. Liu. J. and Unsworth. B.R. Microgravity decreases tyrosine hydr_xylase

expression in rat adrenals. FASEB J.. in press, (1994).

Lelkes, P.I., Ramos, E.M., Chick, D.M., Liu. J. and Unsworth B.R. "Space flight alters catecholamine-synthesizing

enzyme expression and activity in the rat adrenal medulla." Annual ASCB meeting. Dec. t993.

Lelkes, P.I., Ramos, E.M., Nikolaychik. V.V., Wankowski. D.M., Uusworth, B.R. and Goodwin, T.J. A new. versatile

cell culture medium for diverse normal and transformed mammalian cells. In Vitro, in press, (1994).

Molna.r, G. Schroedl, N.A. Gonda, S.R. and Hartzell, C.R. Skeletal muscle satellite cells cultured in simulated

microgravity. In Vitro Cell. Diff., (Submitted 8/94).

Molnar, G., Schroedl, N.A. Gonda, S.R. and Hartzell, C.R. "Characterization of postnatal myogenesis in a

three-dimensional system." Mil. Biol. Cell, American Society for Cell Biology's 35th Annual Meeting, Nan Fr:.lncisco,

CA, December 1994.

Palkar, S.A., and Lenhoff. A.M. Energetic and entropic contributions to the interaction of unequal spherical double layers.

J. Coll. Interf. Sci., vol. 165. 177-194 (1994).

Palkar, S.A., and Lenhoff, A.M. "Characterization of protein-surface interactions using surface forces apparatus." 8th

International Conference on Surface and Colloid Sciences, Adelaide, South Australia, February 1:_-18. 1994

Richardson, D.C. "Redesigning protein surfaces and crystal contacts." Poster presented at the Duke University Medical

Center Biochemistry Retreat, Beaufort, NC. November 6-8,1994.

Richardson, D.C. "Study of crystallization and solution properties of redesigned protein surfaces." NASA Protein Crystal

Growth Principal Investigator Planning Meeting, Panama City, FL. April 22, 1994.

Rosenberger, F. Boundary layers in crystal growth. Prog. Crystal Growth Charact., vol. 26, 87-98 (1993).

Rosenberger, F. Short duration low-gravity experiments - time scales, challenges and results. Micrograv. Sci. Technol.,

vol. VI, 142-148 (1993).

Rosenberger, F. "Interplay between anisotropic interface kinetics and nutrient bulk transport." Plenary lecture at the

Annual Conference of the German Mineralogical Society, Freiberg, Germany, September 17-23, 1994.

Saltzman. W.M, Beaty C.E, Chung S.W. and Dause R.B. "Polymers for stimulating neurite outgrowth." AIChE Annual

Meeting, St. Louis. MO, November 1993.

Saltzman. W.M., Belt, J. Dai, W. Krewson. C.E. Livingston. T. Parkhurst, M.R. and Shin. M. Synthesis of polymeric

substrates and characterization of cell-polymer interactions. Journal of Cellular Biochemistry Supplement. 18C. 24(1

(1994).

111-677
III. MSAD Program Tasks -- FY1994 Bibliographic Citations

Saltzman. W.M.. Belt J.. Dai W.. Krewson C.E.. Livingston T. Parkhurst M.R. and Shin M. "Synthesis of polymeric

substrates and characterization of cell-polymer interactions." Keystone Symposium on Tissue Engineering. Tats. NM.

February 1994.

Saltzman. W.M.. Dai W. Krewson C.E. and Parkhurst M.R. "Polymers for controlling cell motility and aggregation." Lst

International Conference on Cellular Engineering. Stoke on Trent. UK. 12-15 September t993.

Saroufeem, R.. Ingram, M.. Techy, G.B.. Narayan. S.. Bishai. M.. Craft, J., Spaulding. G.. and Goodwin. T.

"Three-dimensional growth and differentiation of early passages of human tumor ceils in simulated microgravity in NASA

bioreactor." Annual Meeting of the Tissue Culture Association. June 4-7. 1994 at Research Triangle Park, Abstract

SV-1006. Hot Topics Addendum Booklet.

Schall, C., Wiencekl J.M., Yarmush. M.L.. and Arnold, E. Lysozyme crystallization studies at high pressure. J. Cryst.

Growth, vol. 135, 548 (1994).

Schroedl, N.A.. Akins, R.E. Molnar. G. Gonda, S.R. and Hartzell. C.R. "Culture of cardiac and muscle cells in simulated

gravity, In Vitro Cell Diff., in press: (1994)." Society for In Vitro Biology's Annual Meeting, Research Triangle, NC.

June 1994.

Spaulding, G.F. Jessup J.M. and Goodwin T.J. Advances in cellular construction. J. Cell Biochem.. 51. 249-251 (1993).

Spaulding, G.F. Jessup J.M. and Goodwin T.J. Advances in cellular construction. J. Cell. Biochem., 51. 249-251 (1993).

Thiyagarajan, P., and Tiede, D.M. SANS studies of structure and interactions of detergent micelles as applicable to

membrane protein crystallization. Amer. Cryst. Assoc., vol. 22, 75 (1994).

Vunjak-Novakovic, G. Freed, L.E. "Hydrodynamic forces determine in vitro chondrogenesis in a three-dimensional

cell-polymer model system." European Society for Osteoarthrology, Bari. Italy (September 1994).

Wiencek, J.M. "Production of protein crystals suitable for X-ray diffraction analysis: controlling growth rates via

temperature manipulations." Fall Colloquia, Chemistry and Chemical Engineering, Polytechnic University, Brooklyn,

NY, October 5, 1994.

Wiencek, J.M. "Efficient separation from dilute solution via driving force manipulation." University of Iowa. Iowa City,

IA, December 9, 1993.

Wiencek, J.M. "Thermal optimization of protein crystal growth." NASA Protein Crystal Growth Conference. Panama

City Beach, FL, April 26, 1994.

Wiencek, J.M.. Schall, C.A., Li, E., and Arnold, E. "Measurement of enthalpy of fusion of lysozyme crystals by

calorimetry and application to maximization of crystal size." AIChE Annual Meeting, St. Louis, MO, November, 1993.

Abbud-Madrid. A., Fiechmer, G.J., Branch, M.C., and Daily, J.W. "A study of bulk metal ignition in oxygen

atmospheres." The Combustion Institute, Fall Meeting of the Western States Section. WSS/CI 93-079, October 18-19.

1993.

Ground: Combustion Science

Abbud-Madrid, A., Fiechtner, G.J., Branch, M.C., and Daily, J.W. "A study of bulk metal ignition in oxygen

atmospheres." The Combustion Institute, Fall Meeting of the Western States Section. WSS/CI 93-079. October 18-19,

1993.

Aldushin, A., Matkowsky, B., Shkadinsky, K., Shkadinskaya, G. and Volpert, V. Combustion of porous samples with

melting and flow of reactants, accepted by Combustion Science and Technology, (1994).

||__!|*__!__!_|____||_|____*__!|||||!_e____*|*|!_||__|__|_!|_*||__|||_!|_!_|_!_______!_!__!e_!____|_|__*_______*__*|_*e_!___|___s*|_*|__*|!!_**_|_|_____**|_____|__||_*_!*__|____*__!____*__*__|_**_**_**|_||_|||||___!_*!_|!!!|_!_|!_|_e|____|__|_*

111--678
Atreya. A..Agrawal, S.,Sacksteder. K.R.,andBaum.H. "Observations of methane and ethylene diffusion flames

stabilized around a blowing porous sphere under microgravity conditions." AIAA-94-0572. presented at the 32nd AIAA

Aerospace Sciences Meeting, Reno. January 1994.

Buckmaster, J. The structure and stability of laminar flames. Annu. Rev. Fluid Mech. vol. 25. 21-53 (1993).

Buckmaster. J. The role of mathematical modeling in combustion. Combustion in High Speed Flows, Kluwer Academic

Publishers. The Netherlands, 447-459 (1994).

Buckmaster, J. and A. Agarwal "Unsteady spherical flames generated by point ignition of combustible mixtures

containing inert particles." presented at the 5th Int. Conf. on Numerical Combustion in Garmisch, September 27 - October

1. 1993.

Buckmaster. J. and A. Agarwal ....Unsteady spherical flames in dusty gases"." presented at the 25th Int. Symp. on

Combustion, The Combustion Institute. Irvine, CA, July 31 - August 5, 1994.

Buckmaster, J. and Agarwal, A. "Unsteady spherical flames in dusty gases." poster session presentation at the 25th Int.

Symp. on Combustion, Irvine, CA, July 31 - August 4. 1994.

Buckmaster, J. and DiCicco. M. "Acoustic instabilities driven by slip between a condensed phase and the gas phase in

combustion systems." presented at the AIAA 32nd Aerospace Sciences Meeting, Reno, NV. Jan. 10-13, 1994.

Buckmaster. J. and G. Joulin Comb. Sci. & Tech.. vol. 89, 57-69 (1993).

Buckmaster, J. and Jackson, T. "The effect of radiative transport on the thermal-diffusive stability boundaries of premixed

flames." poster session presentation at the 25th Int. Syrup. on Combustion, Irvine, CA, July 31 - August 4, 1994.

Buckrnaster, J. and Jackson, T. The effects of radiation on the thermal-diffusive stability boundaries of premixed flames.

accepted by Combustion Science and Technology, (1994).

Buckmaster. J. and Lozinski, D. "Some topics in revedrse smoulder." presented at the US/Japanese Workshop on

Modeling in Combustion, Kauai, July, 1994.

Buckmaster, J. and Lozinski, D. Some topics in reverse smoulder, to appear in the Proc. of US/Japanese Workshop on

Modeling in Combustion , in Kauai. (August 1994).

Delichatsios, M.A. and Ronney, PD. "Horizontal and lateral flame spread on solids: closure and diffusional Lewis-number

effects." Fall Technical Meeting, Combustion Institute. Eastern States Section. Clearwater Beach, FL. December 5-7,

1994.

DiCicco, M. and Buckmaster, J. Accountic instabilities driven by slip between a condensed phase and the gas phase in

combustion systems. AIAA, 94-0103, (1994).

Dietrich. D. "Relative soot volume fractions in droplet combustion via laser-induced incandescence." Eastern States

Section of the Combustion Institute Fall meeting, 1994.

Eng, J.A., Law, C.K. and Zhu, D.L. "Stabilization mechanisms and burning rates of cylindrical burner flames."

AIAA-94-0571, presented at the 31st AIAA Aerospace Sciences Meeting, Reno, January 1994.

Eng, J.A, Law, C.K. and Zhu. D.L. "On burner-stabilized cylindrical premixed flames in microgravity." Twenty-Fifth

symposium (international) on Combustion. the Combustion Institute, presented, to appear, 1994.

Feng, H.J. and Moore. J.J. "Combustion synthesis of dense ceramic-metal composits." Ann. Mtg. of Am. Cer. Soc.,

Indianapolis. IN, April, 1994.

Feng, H.J. and Moore, J.J. "Combustion synthesis of high performance ceramic-metal composits." High Performance

Metal and Ceramic Matrix Composites. TMS, Warrendale, PA, 1994.

i i I I I I I III IIII I I II III I I I I ii i i i i i i i i I i II i I I i i I I i i i i iI i I I i I I I I i i I i ii i i i I I i i I i i i i ii Ii I I II III I I I I I II I i i I I i i I I I I I I II I I I I I I I I I I I II i ii I i I i i I i I I I II I I I I I I III I I I I I II I I III I I II I I II II i i i i i i ii i I I I i IIi I i I I II I ii i i i i i ii i I i Ii III I I I i i i i i ii I i I I i i i ii i ii i i i i i i i I i i ii

111-679
Feng,H.J.andMoore.J.J.Combustion synthesisofhighperformance ceramic-metal composits. HighPerformance

MetalandCeramicMatrixC_mposites. TMS,ed.K.Upadhya, 157-174(1994).

Feng, H.L and Moore, J.J. ln-situ c_)mbustion synthesis of dense ceramic and ceramic-metal interpenetrating phase

composites, accepted, Met. Met. Trans, (1994).

Fcng, H.J. and Moore, J.J.. The design of an affordable one-step process for the production of a functionally-graded

material (EGM). accepted, J. Mat, Synth. Proc., (1994).

Feng, H.J. and Moore, J.J. Combustion synthesis of dense ceramic-metal composites, accepted, Ceramic Matrix

Composites, Ceramics Transactions, (1994).

Feng, H.J., Hunter. K.R., and Moore, J.J. Combustion synthesis of ceramic and metal-matrix composites. J. Mat. Synth.

Proc. 2, 71-86 (1994).

Fcng, H.J. , K.R. Hunter and J.J. Moore "The application of combustion synthesis in the production of titanium-based

ceramic and ceramic-metal composites." Eng. Found. Conf. on High Temp. Struc. Mater., Hawaii, 1993.

Ferkul, P.V. aqd T'ien, J.S. A model of low-speed concurrent flow flame spread over a thin fuel. Ct_mbustion Science and

Technology ( in print), (1994L

Garbinski. G. and T'ien, J.S. "Ignition and extinction of diffusion flames with radiative losses." Presented at the AIAA

32rid Aerospace Sciences Meeting, AIAA-94-0577, 1994.

Grayson. G.D., Sacksteder, K.R., Ferkul, P.V., and T'ien, J.S. Flame spreading over a solid in low speed concurrent flow:

Drop tower experimental results and comparison with theory. Microgravity Science and Technology, vol. 7, no. 2,

(1994).

Grayson, G.D.. Sacksteder, K.R., Ferkul, P,V., and T'ien. J.S. Flame spreading over a thin solid in low speed concurrent

flow: l)rop tower experimental results and comparison with theory. Microgravity Science and Technology, vol. 7, no. 2,

187-195 (1994).

Hegde, U. Heat release effects on the instability of parallel shear layers. AIAA Journal (accepted), vol, 31 no. 1, 206

(January 1994).

Hsu. P.F. and Ku, J.C. Radiative heat transfer in finite cylindrical enclosures with nonhomogeneous participating media.

to appear in AIAA J. of Thermophysics and Heat Transfer, (1994).

Hunter, K.R. and Moore, J.J. "The effect of gravity of the combustion synthesis processing of advanced materials." 6th

Int. Symp. Experimental Methods tbr Microgravity Materials Science, TMS, Warrandale, PA, 1994.

Hunter, K.R. and Moore, J.J. The effect of gravity of the combustion synthesis processing of advanced materials_ 6th Int.

Symp. Experimental Methods for Microgravity Materials Science, TMS, eds. R.A. Schiffman, F.B. Andrews, 125-131

(1994).

Hunter, K.R. and Moore. J.J. Effect of gravity on the combustion synthesis of ceramics and ceramic-metal composites.

accepted, J. Mat. Synth. Proc., (1994).

Hunter. K.R., J.J. Moore "The effect of gravity on the in-situ combustion synthesis of ceramic-metal composites,."

AIAA 94-0568, presented at the AIAA 32nd Aerospace Sciences Meeting at Reno, NV. Jan. 10-13, 1994.

I,ee, C.J.. Buckmaster, J. and DiCicco. M. Intrinsic and acoustic instabilities in flames fueled by multiphase mixtures.

Comb. Sci. & Tech, vol. 98, t61 (1994).

Lozinski. D. and Buckmaster, J. "Quenching of opposed forced flow smoulder." presented at the 1994 Spring Technical

Meeting of the Canadian Section of the Combustion Institute. 10-13 May, 1994.

111-680
Lozinski, D. and Buckmaster. J. Absolute flammability limits and flame-balls. Comb. & Flame. vot, 97. 301-316 (1994L

Lozinski, D. and J. Buckmaster "Quenching of opposed forced flow smoldering combustion." presented at the 1994

Spring Technical IVleeting of the Canadian Section of the Combustion Institute. May 10-13, 1994.

Moore, J.J. "Self proagating reactive synthesis of advanced materials." Keynote Lecture. 1994 Powder Matallurgy Wc_rld

Congress, Paris. June 6-9, 1994.

Moore, J.J. "An examination ol the thermochemistry of combustion synthesis reactions." Processing and Fabrication of

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Black, L.R., Johnson, E.J., Hyer, P.V., Culotta, P.W., and Clark, I.O. "Thermal and fluid effects on MOCVD in a

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Boatner. L.A., David, S.A., and Workman. G. "Gravitaional effects on the development of weld-pool and solidification

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Brain, R.A., H. A. Atwater, and M. Barmatz. "Rapid selective annealing of Cu thin films on Si using microwaves." MRS

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Brown, R.A., Bornside, D.E., Sinno, T., and Zhou, W.-G. "Modelling of bulk crystal growth of silicon." Proceedings of

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Busch. R., Y. J. Kim, W. L. Johnson. A. J. Rulison, and W. K. Rhim. "Determination of specific heat and total

hemispherical emissivity of the highly undercooled Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy." 95th TMS Annual

Meeting, Feb. 12-16, 1994, Las Vegas, NV.

Casagrande, L.G., Larson, D.J., DiMarzio, D., Wu, J.. and Dudley. M. "Growth of large-area, high quality CdZnTe

substrates by the computer controlled vertical Bridgman method." Productibility of II-IV Materials and Devices, H.K.

PoUehn and R. Balcerak, eds., SPIE Proc., 2228, 21-32 (1994).

Casagrande, L.G., Larson, D.J., DiMarzio. D., Wu, J., and Dudley, M. The growth and camparison of large-diameter,

vertical Bridgman CdZnTe and CdTe. J. Cryst. Growth, vol. 137. 195-200 (1994).

Casagrande, L.G., Larson, D.J., DLMarzio0 D., Wu, J., and Dudley, M. "Growth of large-area, high quality CdZnTe

substrates by the computer controlled vertical bridgman method." SPIE Meeting on Producibility of I/-VI Materials and

Devices, Orlando, FL, April 5-8, 1994.

Cezairliyan, A., and Krishnan, S. "Optical properties for high temperature materials research." Microgravity Materials

Science Conference, Huntsville, AL, May 24-25, 1994.

Cezairliyan, A., Krishnan, S., and McClure, J.L. "Laser polar|metric and spectral radiometric measurements of the normal

spectral emissivity of high temperature solids in pulse-heating experiments." 12tb Symposium on Thermphysical

Properties, Boulder, CO, June 21, 1994.

Chert0 C.F and Chert, C.C. Effect of surface tension on the stability of a binary fluid layer under reduced gravity. Physics

of Fluids, vol. 6 no. 4, 1482-1493 (1994).

Chert, M. and Voorhees, P.W. The dynamics of transient ostwald ripening. J. Model and Sire. in Mat. Sci., 1,591 (1993).

Chert, M.T. and Dahm, A.J. "Optical cell for observing solidificaion of helium". Cryogenics 34, (1994).

Clark, I.O. "Thermal diffusion effects in chemical vapor desposition." SIAM Conference on Emerging Issues in

Mathematics and Computation from the Materials Sciences, Pittsburgh, PA, April 18-20, 1994.

Clark, I.O., Jess|r, W.A., Hyer, P.V., and Johnson, E.J. "Microgravity chemical vapor deposition." Proceedings of the

Microgravity Materials Science Conference, Huntsville0 AL, May 24-25, 1994.

Cooper, R.F. "Internal nucleation by oxidation of an iron-doped Calcium-magnesium aluminosilicate melt." American

Ceramic Society, Indianapolis, IN, April, 1994.

Cooper, R.F. "Glass formation and nucleation in microgravity containerless-processed, inviscid silicate/oxide melts:

ground-based studies." MSAD Conference, Huntsville, AL, May 1994.

de Groh IFI, H.C. and Nelson, E.S. "On residual acceleration during space experiments." Heat Transfer in Microgravity

Systems, edited by S.S. Sadhal and A. Gopinathi, HTD - Vol.290, ASME, 1994, pp. 23-33.

i I I| I | | ! | | I Jl I e o I IIiI o I | e | l I | | a II o I | o I I o e I o | Io | I | i I I I I II| Ii I I IIa I ! I I o I I o, I o I I o J l I I I l I o II s I I I I I I I I I I I e oI I I I IIi I o | | o I I a l oI o o o I o I I I I I I II I II I I i I o I o o I o Ia I I a I I I I i I ! ! I! I Io I i I IIi I i i I a i I I I I II | I I I o o I | I I ! I I I I i i i iI ! ilI ! t o ! ili II Ii I e I I I I I I t! II o I I i I I a I Ia II I I I | o o o I

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de Vahl Davis, Graham and de Groth. H.C, "The effect of gravity on natural convection and crystal growth." Proceeding of

the Microgravity Materials Science Conference. huntsville, Alabama. May, 1994.

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Derebail, R., Wilcox, W.R., and Regel, L.L. The influence of gravity on the directional solidification of indium

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DiMarzio, D., Larson, D.J., Casagrande, L.G., Wu, J., Dudley, M., Tobin. S., and Norton, P. "Large area X-ray

topographic screening of II-VI substrates and epilayers." Prodncibility oI [I-VI Materials and Devices. HK. Pollehn and R.

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DiMarzio, D., Larson, D.J., Casagrande, L.G., Wu, J., Dudley, M.. Tobin, S., and Norton, P. "Large area X-ray

topographic screening of II-VI substrates and epilayers." SPIE Meeting on Producibility of II-VI Materials and Devices.

Orlando, FL, April 5-8, 1994.

Domey, J., Aidun, D.K., Ahmadi, G., Regel, L.L., and Wilcox, W.R. "Numerical Simulation of the Effect of Gravity on

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1994.

Dudley, M. "X-ray topography." Applications of Synchrotron Radiation Techniques to Materials Science. D.L. Perry, R.

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Systems, Lexington, MA, December 2, 1993.

Dudley, M. "Synchrotron white beam x-ray topography of II-VI crystals." Invited lecture at Santa Barbara Research

Center, Santa Barbara, CA, April 6, 1994.

Dudley, M., Wu, J., Fanning, T., Larson, D.J., DiMarzio, D., and Lee, M.B. "Use of white beam X-ray topography to

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Diagnostic Techniques for Semiconductor Materials Processing, Boston, MA, November 29-December 2, 1993.

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Dudley. M.. Wu, J.. Larson. D.J., and DiMarzio. D. "Use of white beam X-ray topography to characterize IR detector

manufacturing processes." Diagnostic Techniques for Semiconductor Materials Processing, O.J. Glembocki. F.H. Pollak,

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Dutta, PK.. Jakupca. M., Salvati. L., Reddy, K.S.N.. and Ansari, R.R. Reverse micelle based synthesis of microporous

materials in hydrocarbon solvents. Studies in Surface Science and Catalysts, vol. 84, 235 (1994).

Fanning, T., Dudley, M., and Lee. M.B. Synchrotron white beam X-ray topography study of dislocation propagation from

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Farbshtein. l.I., Parfeniev. R.V.. Yakimov, S.V.. Regel, L.L., Derebail. R., and Wilcox, W.R. "Analysis of Impurity

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High Gravity." Edited by: L.L. Regel and W. R. Wilcox Plenum Press. NY. 1994.

Fradkov, V.E.. Mani. S.S.. Glickman, M.E., Rogers. J.R., Downey, J.P.. Witherow. W.K., Facemire, BR.. and Frazier,

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Hauge, R.H., P. Lee, T. Baykara, and J. L. Margrave. "A review of containerless thermophysical property measurements of

liquid mnetals and alloys". High Temperature Science. (To be published).

Henningsen, T., Singh, N.B., Hopkins, RH., Mazelsky, R., Hopkins. F.K.. Frazier, D.O., and Singh, O.P. Growth of

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Hofmeister. W.H.. Olive, J.R., Bayuzick. R.J., Carro, G., McHugh, J.P.. Hopkins, R.H.. Vlasse, M., V_:eber, J.K.R.,

Nordine, P.C.. and McElfresh, M. "Formation of tetragonal YBa_Cu_OT.s from an undercooled melt." Poster presented at

the MRS Annual Meeting, Fall 1993. Superconductivity: Materials and Processes Symposium, Boston, MA, November,

lq_lq

Huang, W., and Ray, C.S. "Nucleation rate curve for a Li_O.2SiO_ glass by dielectric measurements." 96th Annual Meeting

of the American Ceramic Society, Indianapolis, IN, April 24-28, 1994.

Huang, W.. C. S. Ray, and D. E, Day. Heavy metal oxide glass Part 1: Structural aspect and crystallization behavior. Glass

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Huang, W.. C. S. Ray, and D. E. Day. Heavy metal oxide glass Part 2: structural aspect and crystallization behavior. Glass

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Huang, W., C. S. Ray, and D. E. Day. Color and selected properties of PbO-BiO1.5 -GaOl.5 glasses. J. Am. Ceram. Soc,

77, 1017--24 (1994).

Izmailov, A.F., Arnold, S., and Myerson, A.S. Parametrically driven microparticle in the presence of a stationary

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J. Westhoff and D.W. Readey, "High vapor pressure compounds for modeling of vapor phase sintering." 96th Annual

Meeting of the American Ceramic Society, Indianapolis, IN, April 27. 1994.

Jackson, H.W, Barmatz, M., and Wagner, P. Transient temperature behavior of a sphere heated by microwaves. Ceramic

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i i i i,, i I I I I l i I I i I Iii i I i I I I I I i i i I i l i i i I iii i I I i I I III i t I i i i i i i ii I i i i i i i i i i I I i i I, I I I I I I I I I I i i is i I II i i i i I ii i i i i i i i ii i i i i i i i i i i ill III I I I ii i i iii i ii i i i iiii, i I I I I i ii i i i i ii i i i i i i i i i i i i i i I i ii i i i i, i i, i i. i i. ii. i I i i i I,, i,, i Ii i i i i i is i i i i i i I i i i i i i i, I Ii i i i i i, I i

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Jackson, K.A. "Crystal growth kinetics." Crystal Growth and Epitaxy, Proceedings of the Valais Physical Society, H.J.

Scheet. ed.. 81 (1993).

Jackson, K.A. "Introduction to the modern theory of crystal growth." Proceedings of the 8th International Summer

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Jackson, K.A. Theory of crystal growth from the melt. Ceramic Trans.. vol. 30, 95 f1993).

Jackson, K.A. "Microsegregation." Invited Presentation at the East-West Surface Science Workshop '94 , February, 1994.

Jackson, K.A. "Non-equilibrium phase transformations." NASA Microgravity Materials Science Conference, Huntsville,

AL, May 24-25, 1994.

Jackson, K.A. "Microsegregaton and non-equilibrium crystallization." Invited Presentation at the AACG-West

Conference on Crystal Growth, June, 1994.

Jackson, K.A. "Optical materials in microelectronics." Invited Presentation at the Glass Conference in honor of Prof.

Norbert Kriedl, July, 1994.

Jackson, K.A., Gilmer, G.H.. Temkin. D.E., and Beatty. K. "Microsegregation." Proceedings of the East-West Surface

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Jackson, K.A., Gilmer, G.H., Temkin, D.E., Weinberg, J.D., and Beatty, K. Non-equilibrium phase transformations. J.

Cryst. Growth, vol. 128, 127 (1993).

Kassemi, M., amd Naraghi, M.N.H. Combined heat transfer and fluid flow analysis of semi-transparent crystals in low-g

and 1-g solidification. J. Crystal Growth, (submitted).

Kassemi, M. and Naraghi, M.N.H. Analysis of radiation-natural convection interactions in 1-g and low-g environments

using discrete exchange factor method. International Journal of Heat and Mass Transfer, vol. 36, no. 17, 4141-4149

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Kelton, K.F. Numerical model for isothermal and nonisothermal crystallization of liquids and glasses. J. Non-Cryst.

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Kelton, K.F. "Kinetics of phase transformations in glass forming systems." NASA Microgravity Materials Science

Conference. Huntsville, AL, May 24-25, 1994.

Khan, A., and Pojman, J.A. "Hydrodynamic instabilities in propagating fronts of polymerization." Gordon Research

Conference on Oscillations and Dynamic Instabilities. Newport, RI. August 11, 1994.

Khan, A., and Pojman, J.A. "Convective instabilities in propagating fronts of addition polymerization." Department of

Chemistry and Biochemistry, University of Southern Mississippi, Mississippi Academy of Sciences, Biloxi, MS,

February 17-18, 1994.

Kim, Y.J. and J. H. Perepezko. "Formation of a metastable ferromagnetic phase during containerless melt processing and

rapid quenching in Mn-AI-C alloys." 31st Aerospace Sciences Meeting and Exhibit, American Institute of Aeronautics and

Astronautics, (1993).

Kim, Y.J. and J. H. Perepezko. The formation of a metastable ferromagnetic phase during containerless melt processing

and rapid quenching in Mn-AI-C alloys. J. Appl. Phys, 71,676 (1993).

Kim, Y.J., R. Busch, W. L. Johnson, A. J. Rulison, and W. K. Rhim. "Undercooling studies of the bulk metallic glass

forming Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy during containerless electrostatic levitation processing." 95th TMS

Annual Meeting, Feb. 12-16, 1994, Las Vegas, NV.

I | I I I II ill i i i | e I I |Iii e i I I I I Ie I I i i o e e I lel I I ewe o I e i I I I I I i o i o I I e tili i e I i o i I i Ie | I! I i I I o | I I I I e mII Io I I I I I I IIi i ei i | i i e i i i t i I Ii e i i e I I mIi e II I II i i J i i I I I i i o i ii m| I e o i i i i i | i II I e i i e i | i I e i | I I oI I i i I | i i | I i eo i | e i o o I | o I | | | | i i i; i i i i i i| i i | i i I | i iI o i I o; I I iI e II I ! I e ! I o

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Krishnan. S.. and P.C. Nordine.

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K_rishnan, S., C.D. Anderson and P.C. Nordine. "The optical properties of liquid and solid zirconium". Phys. Rev. B. 49.

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Krishnan, S., C.D. Anderson. J.K.R. Weber, P.C. Nordine. WH. Hofmeister, and RJ. Bayuzick. "Optical properties and

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Krishnan, S.1 J.K.R. Weber, C.D. Anderson, P.C. Nordine, and R.I. Sheldon. "Spectral emissivity and optical properties

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Microgravity Materials Science Conference. Huntsville. AL, May 24-25. 1994.

Lal, R.B., Batra, A.K., Wilcox. WR.. and Trotinger, J.D. "Growth of triglycine sulfate (TGS) crystals aboard the First

International Microgravity Laboratory (IML-1) ." 44th Congress of the International Astronautical Federation, Graz.

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Larson, D.J., DiMarzio, D.. Casagrande, L.G., Carlson, F.M., Lee, T., Steiner, B., Long, G.. Seiler, D.G., Wu, J.. and

Dudley, M. "Producibility improvements suggested by a validated process model of seeded CdZnTe vertical Bridgman

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Larson, D.J., DiMarzio, D., Casagrande. L.G.. Carlson, F,M.. Lee. T., Steiner. B., Long, G.. Seiler. D.G.. Wu. J.. and

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Larson, J. and D.W. Readey, "Low temperature modeling of vapor phase sintering." 96th Annual Meeting of the American

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Lin, C., and Wittl A.F. Decoration of dislocations in Bi_2SiO:0 (BSO) crystals by annealing in a reducing atmosphere. J.

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Lochhead, R.Y., and Rulison, C.J. "The adsorption of hydrophobically modified hydrophilic polymers to oil/water

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Lochhead, R.Y., and Rulison, C.J. "Adsorption of hydrophobically modified water soluble acrylic acid and cellulose based

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Lochhead. R.Y.. and Rulison. C.J. "An investigation of the ability of poly(acrylic acid) microgels to stabilize

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Lochhead. R.Y., and Rulison. C.J. "A study of the adsorption of hydrophobically modified poly(acrylic acids) from

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Cosmetic Chemists National Meeting, Las Vegas, NV. May, 1994.

Lochhead. R.Y., and Rulison. C.J. "The kinetics of polymer diffusion to liquid/liquid interfaces by drop volume

techniques." Southeastern Graduate Student Conference, Hattiesburg, MS, April, 1994.

Lochhead. R.Y., and Rulison. C.J. An investigation of the mechanisms by which hydrophobically modified hydophilic

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Mackowski. D.W., and Knight, R.W. "Numerical modelling of physical vapor transport under microgravity conditions:

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Mackowski, D.W.. Knight, R.W.. Rao, V.R., and Walker, D.G. "Numerical Investigation of thermal creep and thermal

stress effects on microgravity physical vapor transport." NASA MSAD Microgravity Materials Science Conference,

Huntsville. AL, May, 1994.

Mathias, L.J. "Polymerizations in microgravity." NASA Microgravity Materials Science Conference, Huntsville. AL,

May 24-25, 1994.

Mathias, L.J. "Cyclopolymerizations of ethers and ether dimers of RHMA." University of Alabama, Tuscaloosa. AL, June

19, 1994.

Mathias, L.J. "Convection instabilities in propagation fronts of addition polymerization." American Society of

Mechanical Engineers, 14th Annual Winter Conference, New Orleans, LA. December 1, 1993.

Mathias, L.J. "Propagating fronts of polymerization." International Workshop on Dynamism and Regulation in

Non-linear Chemical Systems, Tsukuba, Japan, March 23, 1994.

Mathias, L.J. "Factors affecting propagating fronts of polymerization." MacroAkron IUPAC International Symposium

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Mehrabi, R., and Brown, R.A. An incomplete nested dissection algorithm for direct solution of finite element

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Mtlller, G.. and Ostrogorsky, A.G. "Convection in Melt Growth" chapter in "Handbook of Crystal Growth."

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Myerson, A.S. "Diffusion, viscosity, and crystal growth in microgravity." NASA Microgravity Materials Science

Conference, Huntsville. AL. May 24-25. 1994.

Myerson, A.S. "New results for crystal growth from solution." Fifth Eastern Regional Conference on Crystal Growth,

Atlantic City, NJ, October, 1994.
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Narayan, K.L., Cull, T.S.. Kelton. K.F., and Ray. C.S. "Heterogeneous nucleation in lithium disilicate glass." 96th

Annual Meeting of the American Ceramic Society, Indianapolis. IN, April 24-28, 1994.

Narayanan, R.. Anderson, T.J.. and Fripp, A.L. "An electrocehmical method to measure diffusivity in liquid metals."

NASA Micrograity Materials Science Conference. Huntsville, AL. May 24-25. 1994.

Nastac. L., and Stefanescu. D.M. An analytical model for solute redistribution during solidification of planar, columnar or

equiaxed morphology. Met. Trans., w)l. 24A, 2107-2118 (1993).

Olive, J.R., Hofmeister, W.H., Bayuzick. R.J., Carro, G., McHugh, J.P., Hopkins, R.H.. Vlasse, M., Weber, J.K.R.,

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Olive, J.R., WH. Hofmeister. R.J. Bayuzick. G. Carro. J.P. McHugh, R.H. Hopkins, M. Vlasse, J.K.R. Weber, P.C.

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Ostrogorsky, A.G. "Directional solidification and zone melting using the submerged heater method." General Electric

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ou _______________t_____t__ti___e___i_____ii_ii________o_o_____io_______e___n________m______i__i___t___oio_oo|_ooo_o_______________________ Ollllll Inlln nl!la ___________________n_!tool!___________|_____o_______________________on_e_____o_________n_

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to detect and measure gradients in fluids and materials processing." 6th International Symposium on Experimental

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Zimmerman, F.R. "VPS forming of refractory metals and ceramics for space furnace containment cartridges." Proceedings

of the ASM Thermal Spray Conference, Thermal Spray Industrial Applications, Boston, MA, 457-461 (1994).

Zimmerman, F.R. "Themal spray forming of refractory sample ampoule cartridges for single crystal growth space

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TIT-"/II _
Appendix

A Table of Acronyms ............................................................. A-1

B Guest Investigator Index ................................................... B-1

C Principal Investigator Index ............................................. C-1

iiiiiiii_iiiiiiiiiii_iiiiii_i_ii_iiiiiii_ii_i_ii_i_i_i_i_i_ii_ii_i_i_iIi_i_iii_iii_I_iiii4_ii_i_ii_iIi_i_I_Di_i_ie_I_e_l_i_i_iiI_i_I_I_i_QiIe_i_ii_ii_iijii_iIii_ii_D_i_ii_ii_l_I_

The following list of acronyms, though by no means complete, includes those used in this document as

well as some that are often found in text associated with Microgravity Science and Applications research

and which may be encountered when reviewing references cited in the bibliography herein.

AADSF ...................................................................... Advanced Automated Directional Solidification Furnace

AAL .................................................................................................................................... Aero-acoustic Levitation

ACRT ..................................................................................................... Accelerated Crucible Rotation Technique

AO ........................................................................................................................... Announcement of Opportuni_,

AOMS ....................................................................................................... Advanced Optical Monitoring Systems

APCF .................................................................................................... Advanced Protein Crystallization Facility

APCG ................................................................................................................ Advanced Protein Crystal Growth

ATD .............................................................................................................. Advanced TecLnology Deveh)pment

BDPU ....................................................................................................................... Bubble, Drop and Particle Unit

BTF .......................................................................................................................................... Biotechnology Facility

CADAP ......................................................................................... Computer-Aided Dendrite Analvsis Program

CAST .......................................................................................................... Casting and Solidification Technology

CBE ...................................................................................................................................... Chemical Beam Epitaxy

CCD ..................................................................................................................................... Charge-coupled Device

CFLSE .................................................................................................. Critical Fluid Light Scattering Experiment

CFTE ......................................................................................... Critical Fluid Thermal Equilibration Experiment

CFVME ................................................................................... Critical Fluid ViscosiW Measurement Experiment

CGF ..................................................................................................................................... Crystal Growth Furnace

CM-1 .......................................................................................................................................... Combustion Module

CNES ............................................................................................................. Centre Nationale d'Etudes Spatiales

[The French National Center for Space Studies]

CoDR ............................................................................................................................. Conceptual Design Review

CPF ........................................................................................................................................... Critical Point Facility

CSA ..................................................................................................................................... Canadian Space Agency

CVD .............................................................................................................................. Chemical Vapor Deposition

CVTE ........................................................................................................ Chemical Vapor Transport Experiment

CW ................................................................................................................................................. Continuous Wave

DARA ......................................... Deutsche Agentur ffir Raumfahrtangelegenheiten [German Space Agency]

DARTFire ............................................................................................ Diffusive and Radiative Transport in Fires

DLR ............................................................................................ The German Aerospace Research Establishment

DPM ........................................................................................................................................ Drop Physics Module

DSC .................................................................................................................... Differential Scanning Calorimetry

DSF ..................................................................................................................... Directional 9x_lidification Furnace

DTA ........................................................................................................................... Differential Thermal Analysis

EDM ................................................................................................................... Engineering Development Model

EDS ....................................................................................................................... Energy Dispersive Spectroscopy
EHD ......................................................................................................................................... Electrohydrodynamic

ESA ..................................................................................................................................... European Space Agency

FDSMM .............................................................................. Fluid Dynamics and Solidification of Metallic Melts

FES ................................................................................................................................. Fluids Experiments System

FES/VCGS ............................................................................. Fluid Experiment/Vapor Crystal Growth System

FFEU ....................................................................................................................... Free-Flow Electrophoresis Unit

FFDF .............................................................................................................. Fluid Physics and Dynamics Facility

GaAs .............................................................................................................................................. Gallium Arsenide

GAS Can ......................................................................................................................... Get-away Special Canister

GBX ............................................................................................................................................................... Glovebox

GFFC ............................................................................................................................ Geophysical Fluid Flow Cell

HRT ......................................................................................................................... High-Resolution Thermometer

ICE .................................................................................................................. Interface Configuration Experiment

IDGE ..................................................................................................... Isothermal Dendritic Growth Experiment

IML ............................................................................................................ International Microgravity Laboratory

IWG .............................................................................................................................. Investigator Working Group

JPL .................................................................................................................................... Jet Propulsion Laboratory

JSC ............................................................................................................................................ Johnson Space Center

KSC ........................................................................................................................................ Kennedy Space Center

LaRC .................................................................................................................................. Langley Research Center

LDV ............................................................................................................................... Laser Doppler Velocimetry

LeRC ...................................................................................................................................... Lewis Research Center

LIF ....................................................................................................................................... Large Isothermal Furnace

LPE .................................................................................................................................. Lambda Point Experiment

MCF ............................................................................................................................. Modular Combustion Facility

MEPHISTO ........................................................................ Materiel pour l'l_tude des Phenom_nes Int_ressants

de la Solidification sur Terre et en Orbite

[Interesting Phenomena of Solidification on Earth and in Orbit]

MGM ................................................................................................................... Mechanics of Granular Materials

MMSL ................................................................................................. Microgravity Materials Science Laboratory

MP ........................................................................................................................................... Microgravity Pressure

MPA ....................................................................................................................... Microgravity Pressure, Ambient

MSA ....................................................................................... Microgravity Science and Applications (Program)

MSAD ........................................................................................ Microgravity Science and Applications Division

MSFC .......................................................................................................................... Marshall Space Flight Center

MSL ...................................................................................................................... Microgravity Science Laboratory

NASA ....................................................................................... National Aeronautics and Space Administration

NASDA ....................................................................................... National Space Development Agency of Japan

NIST ........................................................................................ National Institute for Standards and Technology

NLO ............................................................................................................................................... Nonlinear Optical

A-2
NRA ...................................................................................................................... NASA Research Announcement

NRC ................................................................................................................................ National Research Council

OARE ..................................................................................................... Orbital Acceleration Research Experiment

OLMSA ........................................................................... Office of Life Sciences and Microgravity Applications

OMCVD ................................................................................................ Organometallic Chemical Vapor Epitaxy

OPCGA ....................................................................................... Observable Protein Crystal Growth Apparatus

PBE ..................................................................................................................................... Pool Boiling Experiment

PCG ....................................................................................................................................... Protein Crystal Growth

PDA ........................................................................................................................... Phase Doppler Pneumometer

PIV ................................................................................................................................. Particle Image Velocimetry

PMZF ................................................................................................................ Programmable Multizone Furnace

POCC ........................................................................................... Pavload Operations Control Center (at MSFC)

PVT ................................................................................................................................... Physical Vapor Transport

RAPIV .................................................................................................. Radiographic Particle Image Velocimetry

RDR ..................................................................................................................... Requirements Definition Review

RPCVD ................................................................................ Remote Plasma-enhanced Chemical Vapor Epitaxy

RSD ..................................................................................................................... Rainbow Schlieren Deflectometry

RTE .............................................................................................................................. Radiative Transfer Equation

QSAM .......................................................................................... Quasi-steady Acceleraton Measurement System

SAA ..................................................................................................................................... South Atlantic Anomalv

SAMS ................................................................................................... Space Acceleration Measurement Systems

SCF ................................................................................................................................................. Supercritical Fluid

SEM .......................................................................................................................... Scanning Electron Microscopy

SL ................................................................... ESA Spacelab (in Space Shuttle cargo bay; e.g., IML and USML)

SQUID ..................................................................................... Superconducting Quantum Interference Detector

SSCE .......................................................................................................... Solid Surface Combustion Experiment

SSFF .......................................................................................................................... Space Station Furnace Facility

STDCE ....................................................................................... Surface Tension Driven Convection Experiment

STEP ..................................................................................................... Satellite Test of the Equivalence Principle

STS .............................................................................................................................. Space Transportation System

SVP ........................................................................................................................................ Space Vehicle Pressure

TEM .................................................................................................................. Transmission Electron Microscopy

TEMPUS ................................................................................ Electromagnetic Containerless Processing Facility

TGDF .................................................................................................................. Turbulent Gasjet Diffusion Flames

TME .................................................................................................................. Test and Measurement Equipment

TMS .......................................................................................................................... Thermal Maneuvering System

USML ........................................................................................................ United States Microgravity Laboratory

USMP ............................................................................................................. United States Microgravity Payload

VCGS ........................................................................................................................ Vapor Crystal Growth System

A-3
AppendixA: MSADProgram--FY1994 TableofAcronyms

_lllOllalll.llll.ll011OllOl.llllllttuaoll.t.llllatlllllatll.lllllOlllt laOlalallll.l.lll.lllO "t_l|l_o_on_o_l_l_l_l_o_tI_"I_Il_l_l"_o_a_l_H Ollllllll0111tlltlllllUllUllllllOllllalllnlllll

VDA ............................................................................................................................... Vapor Diffusion Apparatus

VIBES ......................................................................................... Vibration Isolation in a Box Experiment System

XRD ................................................................................................................................................. X-rav Diffraction

'III_ag_Io_i1_IaoI_t_n_o_j_m_I_l_Il_iuoi_o_ju_IonI1_I_oDa_uo_B_I_oi_t_D_o_g_o_g_n_g_B_I_iuot_o_oo_I_i_I_Io_o_1_nI_o_a_iq_I_m_a_o_o_a_t_I_I

A-4
AppendixB:MSADProgram-- FY1994 Guest Investigator List

University of Alabama Guest Investigators (cf. p. II-27) (Note: L.Delucas is PI)

Academic: Domestic

W. F. Anderson -- Vanderbilt University

E. Arnold -- Rutgers University

J. K. Baird -- University of Alabama, Huntsville

C. W. Carter, Jr. -- University of North Carolina, Chapel Hill

W. J. Cook -- University of Alabama, Birmingham

E. W. Czerwinski -- University of Texas, Medical Branch

L. J. DeLucas -- University of Alabama, Biringham

G. K. Farber -- Pennsylvania State University

J. R. Knox -- University of Connecticut

K. L. Krause -- University of Houston

O. Lel-Kabbanin -- University of Alabama, Birmingham

A. McPherson -- University of California, Riverside

E. J. Meehan -- University of Alabama, Huntsville

E. F. Meyer -- Texas A&M University

T. L. Nagabhushan -- Schering-Plough Research Institute

S. Narayana -- University of Alabama, Birmingham

R. J. Naumann -- University of Alabama, Huntsville

D. H. Ohlendorf- University of Minnesota

W. M. Rosenblum -- University of Alabama, Birmingham

V. K. Senadhi -- Temple University

L. Sieker -- University of Washington

P. B. Sigler -- Yale University

C. Smith -- University of Alabama, Birmingham

D. Smith -- Medical College of Buffalo

M. Sundaralingam -- Ohio State University
Appendix B: MSAD Program-- FY1994 Guest Investigator List

a0|l*|l!*10|lSl011*lt !|*l|lg011*P!l!*lli!*tl|l j_|!!*_*|!a*!_||**_!_*_¢_|!_*liI|i_I*_I_I**Ii*!i!_*¢|I¢_*_*!_|D_|Do|!!1*il!!*¢*l!*_*_*D!_*I¢*I_o!I!o¢*t!*i!*i!*H*_|!_!I**_M*Di*_!_*!i*!|*_|!!*!!*!_|i!*_¢el!*H*H_H*|o_|*_*t!_)_*H!I!

University of Alabama Guest Investigators (cf. p. II-27) (Note: L.Delucas is PI)

D. Voel -- University of Pennsylvania

W. W. Wilson -- Mississippi State University

Academic: Foreign

S. Abara- Kyoto University (Japan)

C. Betzel -- European Molecular Biology (Germany)

L. T. Delbaere -- University of Saskatchewan (Canada)

G. G. Dodson -- University of York (England)

J. Drenth -- University of Gronmgen (The Netherlands)

W. G. Lever -- The Australian National University (Australia)

K. Moore -- University of Alabama, Birmingham

P. G. Righetti -- University di Milano (Italy)

W. Weber- University of Hamburg

D. Yang -- McMaster University (Canada)

Industry: Domestic

Y. S. Babu i BioCryst Pharmaceuticals, Inc.

D. J. Duchamp -- The Upjohn Company

D. S. Eggleston -- Smith Kline Beecham Pharmaceuticals

H. M. Einspahr -- Bristol-Meyers Squibb

B. C. Finzel -- The Upjohn Company

N. D. Jones -- Eli Lilly Research

M. A. Navia -- Vertex Pharmaceuticals, Inc.

P. Reichert -- Schering-Plow Research Institute

B. H. Rubin -- Eastman Kodak Company

F. R. Salemme -- 3-Dimensional Pharmaceuticals, Inc.

_t_D*_i_o*_*_*_¢_t_*_j_*_*_*I_I*_w_t_t_t_em_t_m*_*_t_*_*_i_t_I_Ie_i_DI_o*_e_e_*_*e_eI_e*_e_s_e_e_t_

B-2
Appendix B: MSAD Program-- FY1994 Guest Investigator List

,*l*|llll*,l*ll*ll,H *, H*ll*ll*lll!ll*ll*l,Ull*ll*ll|,ll*,l,,,.I.l,*l|*tl*l,*,*H,*H _*_*ii_ji*I*l_Hi_ii_ii_i_*_j*H**_Hi_|_|iii_iis_Iiui**I_*iiH_*_l"_i_i_H_"_*_*_**_*l_ii_||_**it_*lmi*_*||*t lit ml*,l*l,|*ll.ll.ll,tl.I.

University of Alabama Guest Investigators (cf. p. II-27) (Note: L.Delucas is PI)

R. M. Swee -- Associated Universities, Inc.

J. Thomson -- Vertex Pharmaceuticals, Inc.

P. P. Trotta -- Schering-Plough Research Institute

K. D. Watenpaugh -- The Upjohn Company

P. C. Weber -- Dupont Merck Pharmaceutical Co.

Industry: Foreign

Government: Domestic

D. Carter -- NASA Marshall Space Flight Center (MSFC)

R. S. Snyder -- NASA Marshall Space Flight Center (MSFC)

K. Ward -- Naval Research Laboratory. (NRL)

Government: Foreign

C. Betzel -- EMBL/DESY (Germany)

G. I. Birnbaum -- National Research Council of Canada (Canada)

J. Fontecilla Camps -- CENG LCCP/LIP (France)

A. Yonath -- DESY/MPG (Germany)

Appendix C: MSAD Program-- FY1994 Principal Investigator Index

*oa_oamIoI*1o*oo*aIia|*a*Io_***oea*¢t*|*aIo1*|*a**ai|**o**o_o_o_**io*ao*a_oa*****a*_a*oa*oa**_oo*6a**_Do*Da*oaD**D*aDoa*aD_i_D_DaDDa*_iaD**_*D*D*||**||*aD*D|DD_M*DDa_DDD|D*Do_D*_*|*DDD4*_ JDODDDD*DDD**DaD*DDD*a*D*ODD*D*OD*ODDIO**I**OOD*DD*DDO*O

Prof. Reza AbbaschianD Ph.D.

Dr. Davood Abdollahian

Prof. Bruce J. Ackerson

Prof. Ajay K. Agrawal

Prof. Guenter Ahlers

Prof. Iwan D. Alexander

Prof. Spiro D. Alexandratos

Prof. Robert A. Altenkirch

Prof. C. D. Andereck

Department of Materials Science and Engineering

University of Florida

132 Rhines Hall

GainesvilleD FL 32611-2066

OfficePh: 904 392-1454 Fax: 904 392-6359 ...................................... !.!2

S. Levy Incorporated

3425 S. Bascom Avenue

Campbell D CA 95008-4870

Office Ph: 408 377-4870 Fax: 408 371 -6804 ........................................... 337

Department of Physics

Oklahoma State University

Stillwater, OK 74078

Office Ph: 405 744-5796 - 339 Fax: 405 744-6811 ...........................................

School of Aerospace and Mechanical Engineering

865 Asp Avenue, Room 212

University of Oklahoma

Norman, OK 73019

Office Ph: 405 325-1754 Fax: 405 325-1088 ...................................... 250

Director, Center for Nonlinear Sciences

Quantum Institute

University of California, Santa Barbara

Santa Barbara, CA 93106

Office Ph: 805 893-3795 Fax: 805 893-4170 ...................................... 159

Center for Micmgravity and Materials Research

University of Alabama, Huntsville

Huntsville, AL 35899

Office Ph: 205 895-6887 .................................................................. 340

Department of Chemistry

University of Tennessee

575 Buehler Hall

Knoxville, TN 37996-1600

OfflcePh: 615-974-3399 Fax: 615-974-3454 ..................................... _

Dean, College of Engineering

Mississippi State University

P.O. Drawer DE

Mississippi State, MS 39762-5543

OfflcePh: 601 325-2270 Fax: 601 325-8573 ............................. .36.D.38. 4.1

Department of Physics

Ohio State University

174 W. 184 Avenue

Columbia, OH 43210

OfficePh: 614 292-2360 Fax: 614 292-7557 ...................................... ?_

II Ill llilIi li Ill Ii III llli Dli Ill II, lii III. I11 IIi lii llli Iil Iii Ill I I I I IIi I I¢ lli I II III II i I I i I I i Ili III II illl IIililil I Iiili III i III liI Illi III I .I III* ill *lilill Ill Illl ill Ill IIII Ili III I i Ill IiI I l.I I I I i I I i lI i III I I, Ill lIII ili III ill Ill IIi IIillli II i IIIllI III I

C-I
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

o i o a e oa o o o o,#a ,,a Dog Jol |o o i e a o o i o, o | o i HI o ii o ol o | o a i i J o o o go i oo o o o o o o o t o * Du o oo | Do a o o o * o o i io o | o * Do i o o oBoa oo o J | i * i a Bo o o oo i, o _ a o o oo it o i o o o i I o o i o o ao o a o o o _ o o o o | o io o o o * _ o o o _ _ o | o a _ _a o _o _ o o _ o _ o o _ a o oo _ _ _ o o o a o I o _ o _ o | o_ | o o o o o | o o _ | * _ _ o | o o | o _ | o a oo a H _ n 0 0 0BD|

Prof. John L. Anderson

Dr. T. J. Anderson

Dr. J. B. Andrews

Prof. Robert E. Apfel

Prof.Stephen Arnold

Prof. Arvind Atreya

prof. C. T. Avedisian

Dr. William D. Bachalo

Department of Chemical Engineering

Carnegie Mellon University

5000 Forbes Avenue

Pittsburgh, PA 15213-3890

Office Ph: 412-268-6986 Fax: 412-268-7139 ..................................... ?_

Department of Chemical Engineering

University of Florida

227 Chemical Engineering Building

Gainesville, FL 32611

Office Ph: 904-392-0882 Fax' 485 904-392-9513 ..........................................

Department of Materials Science & Engineering

BEC 360

University of Alabama, Birmingham

1150 Tenth Avenue South

Birmingham, AL 35294-4461

Office Ph: 205-934-8452 Fax: 205-934-8485 ..................................... 1.!5

Robert Higgin professor of Mechanical Engineering

Department of Mechanical Engineering

Yale University

P.O. Box 208286

NewHaven, CI" 06520-8286

Office Ph: 203 432-4346 Fax: 203 432-7654 ................................. .7.2.:.4.8.7.

Department of Physics

Polytechnic University

Six Metrotech Center

Brooklyn, NY 11201

OfficePh: 718-260-3085 489 Fax: 718-260-3085 ..........................................

Department of Mechanical Engineering and Applied Mechanics

University of Michigan

2158 GG Brown

Ann Arbor, MI 48109-2125

Office Ph: 313 747-4790 Fax: 313 747-3170 ...................................... 252

Sibley School of Mechanical and Aerospace Engineering

Cornell University

Ithica, NY 14853-7501

Office Ph: 607 255-5105 Fax: 607:255 1_ 254, 346

----v- ........ o ............ ,.o,**...o..,. o, ,o,....,..

President

Aerometrics, Inc.

550 Del Rey Avenue

Sunnyvale, CA 94086

Office Ph: 408 738-6688 Fax: 408 738-6871 ..................................... _

ooeooeee_|g_moela,no_l_ooeo_o_o|ooooeoeeoeeoeoeeooanlollooa lot olooolooaoootooalog ooooloo Jog [,o,I !lo ooaooloioo ioa too ooooo* ooo Ioo ooooll oloeo! [,o!looloo! oo! oon ooa;¢!oooooo! ;ooooo! ;onoooo ooo ooo oo! n(,!n_oan_!! o!! ooooloa I_aa;oa oo! IOOOOaleaOOOlIOOOOOO0OI(,OOOO_

C-2
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

_***e_*_***_|*_*_*_*|_|*_|o_****D_*|**_*_|*_I4**_*_M*|g*_*,_**_**_*|*_!_*I*_|_*_**|_**_**_*_*_t*_*_*_¢*|_*||_|_||_*_*|_t_*_|*|*_**H*_*_*|_**_N_**_*_****_*e_*t**_*_*H_*_|_*a_|**||_*n_|*e|**|

Dr. M. Y. Bahadori

Dr. Martin B. Barmatz

Prof. James C. Baygents

Prof. Robert J. Bayuzick

Prof.Jeanne L. Becker, Ph.D.

Prof. Christoph Beckermarm

Dr. Robert F. Berg

Dr. Mark Bethea

Thermal Sciences Division

Science Applications International Corporation

21151 Westem Avenue

Torrance, CA 90501-1724

OfflcePh: 310 781-8723 Fax: 310 781-8730 ....................................... 43

Technical Group Leader

Mail Stop 183-401

Jet Propulsion Laboratory

4800 Oak Grove Drive

Pasadena, CA 91109

Office Ph: 818 354-3088 Fax: 818 393-5039 ......................... 16.!:.49.1:.626

Department of Chemical and Environmental Engineering

The University of Arizona

Harshbarger Building, Room 120

Tucson, AZ 85721

Office Ph: 602-621-6044 Fax: 602-621-6048 ..................................... 347

Department of Applied and Engineering Science

Materials Science and Engineering Program

Vanderbilt University

Box 1593, Station B

Nashville, "IN 37235

Office Ph: 615-322-7047 Fax: 615-343-8645 ........................ 1..17:..4..9.5.:..4..93

Department of Obstetrics and Gynecology

University of South Florida

4 Columbia Drive

Tampa, FL 33606

OfficePh: 813 254-7774 Fax: 813 254-0940 ...................................... 198

Department of Mechanical Engineering

University of Iowa

Iowa City, IA 52242

497 OfficePh: 319 335-5681 Fax: 319 335-5669 ...........................................

Thermophysics Division

l_ationalInstituteof Standards and Technology

Building 221, Room AI05

Gaithersburg. MD 20899

OfflcePh: 301 975-2466 Fax: 301 869- 4020 ..........................................

74

NASA Lewis Research Center

21000 Brookpark Road

Cleveland, (31-I 44135

OfflcePh: 216 433-8165 Fax: 216 433-5033 ...................................... 628

I I I I I I I I lI I IIII I I I IN I ! I! I I Ill t01 IllIll I II eli III I II I I I I II II I J I I I I I I I I I II I I I I I I I I II I II I II I I I I! I I I I I II I l II Ill It I I I I If I I I I I I II It I III II I I I I I II I I I I I I I II I I I I I I I I If IIIHll I Ill It I I I lll III I I It I Ill I II I II I I I I I Ill I I I I I lI I II I I I II I ItIlllI IlIII I I I IIlII Ill It If

C-3
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

ol Po* olelnooo DO,I.o_|oQoeOOoU.......O. O,, .6, .....o, ...., O..,, .|a. ,u .,,, ,. ,...o. or, IO, *6g .It, .J.o,,a. ,t., ,* O, ... |. to*, O*,oa no| *,,,to* too .JOin OO.o ,.a Jou|to,,,,tO tea *OlnIOlOlOOt|anItOOOOOOOOIOOOOa HI Ira oeooOoInolo|OOotea JOa toa|olloto|_teto_|uluooooo

Dr. Lynn A. Boamer

Prof. Melvyn C. Branch

Prof. Robert A. Brown

Prof. John D. Buckmaster

Prof. Van P. Carey

Dr. Daniel C. Carter

Dr. Peggy Cebe

Head, Ceramics arid Interfaces Section

Solid State Division

Mail Stop 6056

Oak Ridge National Laboratory

P.O. Box 2008

Oak Ridge, "IN 37831

Office Ph: 615-574-5492 Fax:

500

615-574-4814 ..........................................

Center for Combustion Research

University of Colorado

Engineering Center, Campus Box 427

Boulder, CO 80309-0427

OfflcePh: 303 492- 6318 Fax"

256, 258 303 492-2863 ...........................................

Head, Department of Chemical Engineering

Chemical Engineering & Materials Processing Center

Room 66-342

Massachusetts Institute of Technology

77 Massachusetts Avenue

Cambridge. MA 02139

Office Ph: 617-253-4561 Fax: 617-253-9695 502, 505

o,..o,.. .... *°.,.° .... .o... ...... ***.. ....

University of Illinois at Urbana-Champaign

Room 321 Talbot Lab

104 Wright Street

Urbana, IL 61801

259

OfflcePh: 217 333-1803 Fax: 217 244-0720 ...........................................

Mechanical Engineering

University of California

6185 Etcheverry Hall

Berkeley, CA 94720

Office Ph: 510 642-7177

349

Fax: 510 642-6163 ...........................................

Chief, Biophysics Branch

Microgravity Science and Applications Division

ES76

NASA Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

23, 25, 200 Office Ph: 205-544-5492 Fax: 205-544-1777 ..........................................

Department of Materials Science & Engineering

Room 13-5082

Massachusetts Institute of Technology

77 Massachusetts Avenue

Cambridge, MA 02139

508 Office Ph: 617-253-8638 Fax: 617-258-7874 ..........................................

_u_u_q_`_te#_4_#_`_4_#__n_ _g___________n___n___|___g_______g_________n__________________n____n_____gM____________n_jg_n__n____u_____g_MM___g___n_n______________g_____g_______________n________!_ _ ,_L, i

C-4
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

_u__4__________o_o_o_o_

Dr. Axed Cezairliyan

Dr. An-Ti Chai

Prof. Paul M. Chaikin

ProL $. H. Chart

ProL Chuan F. Chen

Prof. L. D. Chem

Dr. Robert K. Cheng

Prof. Norman Chigier

Program Leader, Metallurgy Division

Building 236

National Institute of Standards and Technology

Gaithersburg, MD 20899

Office Ph: 301-975-5931 Fax: 301-990-2572 ..................................... 5.!O

NASA Lewis Research Center

MS 500-327

21000 Brookpark Road

Cleveland, OH 44135

Office Ph: 216 433-2073 Fax: 216 433-8660 ...................................... 75_

Department of Physics

Princeton University

P.O. Box 708

Princeton, NJ 08544

Office Ph: 609 258-4338 Fax: 609 76 258-6360 ...........................................

Department of Mechanical Engineering

University of Wisconsin, Milwaukee

P.O. Box 784

Milwaukee, Wl 53201

OfficePh: 414 229-5001 Fax: 414 229-6958 ...................................... 352

Department of Aerospace and Mechanical Engineering

College of Engineering & Mines

University of Arizona

Tucson, AZ 85721

354, 512 OfficePh: 602 621-8199 Fax: 602 621-8191 ...........................................

Department of Mechanical Engineering

The University of Iowa

Iowa City, IA 52242

OfflcePh: 319 335-5674 Fax: 319 335-5669 ...................................... 2.63

Combustian Group

Energy & Environment Division

Lawrence Berkeley Laboratory

1 Cyclotron Road

Berkeley, CA 94720

office Ph: 510 486-5438 Fax: 510 486-7303 ............................... 266:.268

Department of Mechanical Engineering

Carnegie Mellon University

Schenley Park

Pittsburgh. PA 15213-3890

OfficePh: 412 268-2498 Fax: 412 268-3348 ...................................... 356

eioxeRoeeeee eo!los e(,i solsoenno e| sos sell so | eo| sole osat oa is aoooo_ aIol i oa i oaooa i oa ioa i I i ooa soasoo| ! ! I I s sol ooaoso i oo ooi i oi o. ooi ooi oooo. i s| | i oi ss| oo. oi ooso ooI aoI ! oso! i so | I oo io ao| oaI oo. ooooooooooI o* | o. ooI oi I o. o| |oi |os i o! o. ooos| sso oooosos ooso ooa |o oo

C-5
Appendix C: MSAD Program --FY1994 Principal Investigator Index

aeoaeouNeen.04|e| oH oe(*tea or* tea tta to oooIt OO0tea | t i 0aoo, oo, o, oo oooooo| oaoo| itt, iotot |, | t agi ao ti ot oot oot, o !oo! oo, _oo|o !ao! ! eoa* ! !e,, it! * | t _a* oBo,, !ntit ot at! ooo! it! o| | oa ot ot g! t oo| nt! ao, o, it, oot oot J ooooooaeo! o IoI, oooatoItt ootoot otu to a |o| too _(*o tee _eotoatoa t,

Prof. Mun Y. Choi

Dr. Talso C. Chui

Prof. Jacob N. Chung

Dr. Ivan O. Clark

ProL Noel A. Clark

Prof. Paul Concus

Dr. Reid F. Cooper

Dr. Sam R. Coriell

Department of Mechanical Engineering

M C251

University of Illinois, Chicago

842 W. Taylor Street

Chicago, IL 60607-7022

OfflcePh: 312 996-7389 Fax: 312 413-0447 ....................................... .4.6

Jet Propulsion Laboratory

Mail Stop T1702

4800 Oak Grove Drive

Pasadena, CA 91109-8099

OffLcePh: 818 354-3104 Fax: 818 393-4878 .............................. 1.63:.1.65

Department of Mechanical and Materials Engineering

Washington State University

Pullman, WA 99164-2920

358 OfficePh: 509 335-3222 Fax: 509 335-4662 ..........................................

Information & Electromagnetic Technology Division

Mail Stop 473

NASA Langley Research Center

5 North Dryden Street

Hampton, VA 23681-0001

Office Ph: 804 864-1500 Fax: 804 864-7891 ........................ .3.6.0:.36.2.:..5.!3

Department of Physics

University of Colorado

Boulder, CO 80309-0390

OfficePh: 303 492-6420 Fax: 303 492-2998 ...................................... _._

Lawrence Berkeley Laboratory

University of California, Berkeley

1 Cyclotron Road

Berkeley, CA 94270

Office Ph: 510 486-5508 Fax: 510 486-5401 ...................................... 3.65

Materials Science and Engineering

University of Wisconsin

1509 University Avenue

Madison. WI 53706

Office Ph: 608 262-1133 Fax: 608 262-8353 ...................................... 5.!.5.

National Institute of Standards and Technology

Materials Building 233, Room B-166

Gaithersburg, MD 20899

OfflcePh: 301 975-6169 Fax: 301 975-2128 ...................................... 369

t_oaom4nHtt moHt4Nat4uto_teNNmua_to |o6nneo|eat| too tea t g* oto ot to t oooootoo! oat oot ooot aoI t *ano, t t o, oot ooooa* oa, o, J t no,, ot o,,, t,, oI a., I *, at t oott * to*, t o,. o,, oo* t o*, o, o ooo.o, I o* oooat t to to * o,* to, o,, * De* |, o|o o, oat I a*, oo oa., o... t. ot gl oo tuo.o m mmu41ta,

C-6
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

a,.t i ooou,tt ooootoa too olo oooo| oa_o* too t Je J M t o. | oot ooi. oo, o*,,,, oo, o,, ,.,, o, oo. oo*, o*, oo, o*,,,, o,,, o,, oDo*,, o. a.,,., o., o,. o,., a*, o., oo, oo, o, t o,*. o. _oo, oo| oot, ot oowoo. ooDoat t ooo o* tot ooooeoI Io oot o* Jlo o,.o oD*a Dooo peaI¢ oooootoo etOHH0 o|eouoal_n_Pmonl

Dr. Peter Curreri

Prof. Arnold Dahm

Prof. Robert H. Davis

Prof. Stephen H. Davis

Dr. Delbert E. Day

Dr. Graham D. de Vahl Davis

Dr. Lawrence J. DeLucas

Dr. Daniel L. Dietrich

Microgravity Science & Applications Division

ES75

NASA Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

Office Ph: 205-244-7763 Fax: 205-544-1777 630

. ,.,o,..o .. ,,,, o,,, .,,., .oo...o.o.....,...

Physics Department

Case Western Reserve University

10900 Euclid Avenue

Cleveland, OH 44106

Office Ph: 216 368-3586 Fax: 216 368-4671 ...................................... 5.!_

Department of Chemical Engineering

University of Colorado

Campus Box 424

Boulder, CO 80309

Office Ph: 303 492-7314 Fax: 303 492 4341 371, 373. 375

Department of Engineering Sciences

and Applied Mathematics

Northwestern University

2145 Sheridan Road

Evanston, IL 60208

OfficePh: 708 491-5397 Fax: 708 491-2178 ...................................... 377

Graduate Center for Materials Research

Materials Research Center

University of Missouri, Rolla

Rollao MO 65401

OfflcePh: 314 341-4354 Fax: 314 341-2071 ...................................... 520

School of Mechanical and Manufacturing Engineering

University of New South Wales

Sydney, Aust 2052

AUSTRALIA

OfflcePh: 612 697-4099 Fax: 612 663-1222 ...................................... 5.24

Center for Macromolecular Crystallography

79-THT, BHSB 262

University of Alabama, Birmingham

1918 University Boulevard

Birmingham, AL 35294-0005

Office Ph: 205-934-5329 Fax: 205-934-0480 ...................................... 27

NASA LeRC Group

MS 500-217

NYMA, Inc.

Brook Park, OH 44146

OfficePh: 216 433-2875 48, 269 Fax: 216 433-3793 ...........................................

ua ot_i ,nao,n,u OKOOH¢0 | toO I00 It. tO¢le0 SO0tO,,t IStea ,,oo,,ooooo*. o,., o. t .a ,b,b,. 0O,'O0OO0000 O| t atI aooO. Ooo| OaoOatsa|., oa. ot *. | oom,_,. 8o.,, oot,., | o.. oa.., * * ,uo. a. taot oooooio.. oo. too. Do,,o. ooDoi oHa *, oooo. o*. * Do,,t oo,bo.., ooo.o ooa to. t s. oo ,uoo o,nso. oeo,boooi,o o

C-7
Appendix C: MSAD Program --FY1994 Principal Investigator Index

4o_oo0_uuma.nlqtt Meueeo et|ou|oo t tHoot¢o |co|co |o o| |o ! eooeDeott 4ooo. t ooooot! | t ooooooooooot ooi oot oot annt aot oot ooI oqaIto| t oot o* t | oooI| tdaitodoit, ooooe it t| itoiiot o0aooinooo toato a| t ot oo it ooito! ooooi _ooee t ooit o,, o! eoI o|oa toa| _oe| oaitoa|, atoooooinit, g|t oPto toe to o| oanlo| nta

Prof. Russell J. Donnelly

Dr. Edward L. Dreizin

Prof. James F. Driscoll

Dr. Michael Dudley

Dr. Robert V. Duncan

Prof. Douglas J. Durian

Prof. Prabir K. Durra

Prof. Fokion N. Egolfopoulos

Prof. Charles Elbaum

Physics Department

University of Oregon

Will,metre Hall

Eugene, OR 97403

Office Ph: 503 346-4226 166, 168 Fax: 503 346-4708 .....................................

AeroChem Research Laboratories

P.O. Box 12

Princeton, NJ 08542-0012

271 Office Ph: 609 921-7070 Fax: 908 329-8292 ...........................................

University of Michigan

3004 FXB

AnnArbor, MI 48109-2118

Office Ph: 313 936-0101

273

Fax: 313 763-0578 ...........................................

Department of Materials Science & Engineering

State University of New York at Stony Brook

Stony Brook. NY 11794-2275

526 Office Ph: 516-630-8500 Fax: 516-632-8052 ..........................................

Department 9255

MS 09880

Sandia National Laboratory

Allmquerque, NM 87185

Office Ph: 505 844-4833 Fax: 505 844-2057 .........................................

Department of Physics

University of California, Los Angeles

405 Hilgard Avenue

Los Angeles, CA 90024

Office Ph: 310 206.2645 Fax:

378 310 825-0897 ..........................................

Department of Chemistry

Ohio State University

120 West Eighteenth Avenue

Columbus. OH 43210

Office Ph: 614 292-4532

530

Fax: 614 292-1685 ....................................

Department of Mechanical Engineering

University of Southern Ctlifomia

University Park

Los Angeles, CA 90089

275 Office Ph: 213 740.0480 Fax: 213 740-8071 ...........................................

Physics Department

Box 1843

Brown University

Providence, RI 02912

170 OfflcePh: 401 863-2186 Fax: 401 863-2024 ....................................
Appendix C: MSAD Program m FY 1994 Principal Investigator Index

ole |oeooeeauloonnJoe| ee lee |! ! eoonom ! o* nmooeooqa|t ooea amHe I | aooooo ai oooo oooooo! ooa*o o*1 !* igo| ooao| a6ooo* oooil |o | |e ba J i a* | ao| a| oJ ao| aai ooin ae _I ooon* | o| | i i on ne lee | o| Io ! e! ! eool Jooi Ii | i aeooo ooo eo! io ae ooe |o aoeu etoe |on mu oooooee oeln|Heoeo Jee|e6esle no |e4

Prof. Said E. Elghobashi

Prof. C. F. Everitt

Prof. Gerard M. Faeth

Dr. Frank Fendell

ProL A. C. Femandez-Pello

Prof. Richard A. Ferrell

Prof. Merton C. Flemings

Dr. Donald O. Frazier

Department of Mechanical and Aerospace Engineering

University of California, Irvine

Irvine, CA 92717

OfficePh: 714 856-6131 Fax: 714 856-8585 ...................................... 276

Hansen Experimental Physics Laboratory

Gravity Probe B

Stanford University

Stanford. CA 94305

Office Ph: 415 725-4103 Fax: 415 725-8312 ....................................... _!

Department of Aerospace Engineering

University of Michigan

3000 FXB Building

Arm Arbor, MI 48109-2118

OfflcePh: 313 746-7202 Fax: 313 763-0578 ....................................... 50

TRW Applied Technology Division

Space & Technology Division

TRW Space of Electronics Group

TRW

Redondo Beach. CA 90278

OfficePh: 310 812-0327 Fax: 310 814-2359 ....................................... 5_

Department of Mechanical Engineering

University of California, Berkeley

Etcheverry Hall

Berkeley, CA 94720

OfficePh: 510 642-6554 Fax: 510 642-6163 ....................................... 56

Department of Physics and Astronomy

University of Maryland

College Park, MD 20742

Office Ph: 301 405-6148 Fax: 301 314-9465 ................................. !_:.!7_

Head, Department of Materials Science & Engineering

Room 8-309

Massachusetts Institute of Technology

77 Massachusetts Avenue

Cambridge. MA 02139-4307

OfficePh: 617-253-3233 Fax: 617-258-6886 ..................................... !.19

Space Sciences Laboratory

ES01

NASA Marshall Space Flight Center

Marshall Space Flight Center. AL 35812

OfficePh: 205-544-7825 Fax: 205 544 2102 78, 531. 533. 535

___-___- .... o.0oooooo..,o.o° ..... • o,..,...*,,.,.o...,*
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

oe|NNe_eeeoxeReo6exo|e4oeueNouNsoe4oooaeeoooouloolooaloloooan4Doaoooaoo° jH_Iajt_o$_o1_oo_o_oa|o_|H_o_Do1Doa_6a_ogiH_H_ooio_1_oo|_ioo_1_t6j_eo4IIo_|_1_e_Iol_o_o0oo_ioII_Ioooo_eo_o_o_e_o_e_m_eeuee_

Dr. Lisa E. Freed

Dr. Archibald L. Fripp

Prof. Robert W. Gammon

Prof. Stephen Garoff

Prof. Alice P. Gast

Prof. Randall M. German

Dr. Thomas K. Glasgow

Prof. Irvin Glassman

Massachusetts Institute of Technology

M1T E25-342

77 Massachusetts Avenue

Cambridge. MA 02139

202

OfflcePh: 617 253-3443 Fax: 617 258-8827 ...........................................

Information & ElectromagneticTechnology Division

MS 473

NASA Langley Research Center

5 North Dryden Street

Hampton, VA 23681-0001

Office Ph: 804 864-1503 Fax: 804-864-7891 .............................. .1..20:..1..22.

Institute for Physical Science and Technology

University of Maryland

Building 85

College Park. MD 20742

15

Office Ph: 301 405 4791 Fax: 301 314-9509 ...........................................

Department of Physics

Carnegie Mellon University

5000 Forbes Avenue

Pittsburgh, PA 15213

80

Office Ph: 412 268-6877 .......................................................................

Department of Chemical Engineering

Stanford University

Stanford, CA 94305-5025

380

Offlce Ph: 415 725-3145 Fax: 415 725-7294 ....................................

Department of Engineering Science

Pennsylvania State University

118 Research West

University Park, PA 16802-1401

124

OfflcePh: 814 863-8025 .......................................................................

NASA Lewis Research Center

MS 105-I

21000 Brookpark Road

Cleveland, OH 44135

Offlce Ph: 216 433-5014

537

Fax: 216 433-5033 ....................................

Department of Mechanical & Aerospace Eng.

Princeton University

Princeton, NJ 08544

538

Offlce Ph: 609 258-3090 .........................................................

_IH_gg_I|||HIIIUIUIIIIIHIil Ill Ill I n l iii II I I I | I I ooI i i i I i i I I I II I I |l I I ! oi iI Oi i oo* eOoOl i ooooo* i i i i i I*111111 ! I oI ai* oi i l,Oil i i I i I I i II oItl If I I oel I tl I o* i ill n t I i I i oo11111iii I I lOt!leO I# I I I I llg I1! I ! Ill till OIi|II IOII_I_;I_IIUIIH

C-IO
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

n eltll l iI I el l t lit eHie Itlltll Iii I I till l II lIll I tl III I I I I. II..I., I I, I I I I I .I I I( I I I I I I I. !1111. l I I. II l Ill .II,. I .I I .. I III Ill I, l II I I I I I I I I I I I II. I I I, I l., l I. l I II I I l I I. I, tO I I. I .. l.,.... I I I I I l II I I l I, I I lI I I l tl I I I I Ill I I l I I I I I I ill I Il I }11 Ill Ill Ill ill Ill trill

Prof. Martin E. Giicksman

Prof. Anm M. Gokhale

ProL Alessandro Gomez

ProL John A. Goree

Paul S, Greenberg

Prof. lames B. Grotberg

Dr. Richard N. Grugel

Prof. Prabhat K. Gupta

Prof. Hosiein Haj-Hariri

Materials Engineering Department

MRC-104

Rensselaer Polytechnic Institute

Troy, NY 12180-3590

OfficePh: 518 276-6721 Fax:

126

518 276-8554 ...........................................

School of Materials Science and Engineering

778 Atlantic Drive

Georgia Institute of Technology

Atlanta, _ 30332-0245

540 Office Ph: 404 894-2887 Fax: 404 853-9140 ...........................................

Department of Mechanical Engineering

Yale University

New Haven, CT 06520

Office Ph: 203 432-4384 Fax: 203

278 432-7654 ..........................................

Department of Physics & Astronomy

Universityof Iowa

Iowa City. IA 52242-1479

Office Ph: 319-335-1843 Fax: 319-335-1753 83

o o, IHo ooo. ooIHil,i..*I HIiI.ooaI...*.*,.

NASA Lewis Research Center

21000 Brookpark Road

Cleveland, OH 44135

Office Ph: 216 433-3621

632

Fax: 216 433-3793 ..........................................

Northwestern University

Evanston, IL 60208-3112

Office Ph: 708 491-3009

382

,.,,...,,..HHH.,,,..,..,..H*..,,...*H,,.IOH*I''II'HHIHI''HeH

Marshall Space FlightCenter

Mail Stop E575

Huntsville, AL 35812

OfflcePh: 205 544-9165

129

Fax: 205 544-8762 ..........................................

Department of MaterialsScience and Engineering

Ohio State University

2041 College Road

Columbus. OH 43210

541

Office Ph: 614 292-6769 Fax: 614 292-1532 .........................................

Department of Mech and Aerospace Engineering

University of Virginia

Thornton Hall

Charlottesville, VA 22903

383

OfflcePh: 804 924-6290 Fax: 804 982-2037 ...........................................

l::'::';::_:_:: ::: :::: _N_NIm_leoaill Iii ll el ooi otl l ol l t Otll I IHII l i i oii ii i i l l *(i l ill iii ill i i i oii ill Ill I l l I I i l I I l Ill 1OI I I I l I I Ol OOil l OO., Ol l I I Ill Il ONIl 1el Ol loll $ i t ll i i ooii i lI ooill l ii l el I lea lleO I 0011 I IISNIHOHI_gHIH

C-I1
AppendixC:MSADProgram-- FY1994 Principal Investigator Index

ProL J. Woods Halley

Prof. Kevin P. Hall!nan

Dr. John E. Hart

Frank T. Hartley

Dr. Charles R. Hartzell

ProL T. A. Hanon

Dr. Robert H. Hauge

Dr. John Hegseth

Physics Department

University of Minnesota

116 Church SE

Minneapolis, MN 55455

OfflcePh: 612 624-0395 Fax: 612 624-4578 ..................................... !2_

Mechanical and Aerospace Engineering Department

University of Dayton

300 College Park

Dayton, OH 45469-0210

OfficePh: 513 229-2835 Fax: 513 229-3433 ....................................... 85

Department of Astrophysical, Planetary

& Atmospheric Sciences

Campus Box 391

University of Colorado

Boulder, CO 80309-0391

Office Ph: 303-492-8568 Fax: 303-492-3822 ...................................... 87

Supervisor, Advanced Test and Measurement Group

Instrumentation Section

Mall Stop 125-177

Jet Propulsion Laboratory

4800 Oak Grove Drive

Pasadena, CA 91109

OfficePh: 818 354-3139 Fax: 818 354-8153 ...................................... 636

Director of Research

Alfred I. DuPont Institute of the Nemours Foundation

P.O. Box 269

Wilmington, DE 19899

OfflcePh: 302 651-6800 Fax: 302-651-6888 ..................................... 205

Chevron Professor of Chemical Engineering

Department of Chemical Engineering

Massachusetts Institute of Technology

77 Massachusetts Avenue

Cambridge. MA 02139

OfficePh: 617-253-4588 Fax: 617-253-8723 385

.... ,......,,...,,°.°°,...°..,,...... .....

Chemistry Department

Rice University

P.O. Box 1892

Houston, "IX 77252

Office Ph: 713 527-8101 Fax: 713 285-5155 ...................................... _

Department of Physics

University of New Orleans, Lakefront

NewOrleans, LA 70148

Office Ph: 504 286-6706 Fax: 504 286-6048 .....................................3.87

|ilI(INtlIIINNtlIIIIIItlIIIIIIIIIIIINIIIIIIIIIIilIilII Nullnl i tln! it! 101811 it! it! i i1! i Ill i | 141110 ! ! I It! i t(ll s! i !! ! I ! * ! i! ii;! 101011010 ! i ! i iltltl tilt i 1101i i! * i li1101110110Is 10! i i i i I i ! I ! I I! e llll ill 111 ! Ii iitl i i i * i I I t l Ill 10!ltl Ill I!11011 IU 111101 n l iltn4I| Ill ill ill 10.

C-12
AppendixC:MSADProgramu FY1994 Principal Investigator Index

IgSXDOOIOlS0aIOII00_IOOH00HneHOHH00OOHOHJ0HOHOH0XeH_HOHHmIamJ,OII.la|Ia j_HO_j_HHa_H.IaH_H1_o_H_t_t_t_no_H_oH_wo_t_.t_ot4_l_e|o_to_no_H_w_oo_H_o_H_o1_oa_t_o_o_oootH_o_Ho_oo_o_H_oH_mo_.

Dr. Daniel J. Heinzen

Prof. Jean R. Hertzberg

Prof. Simone Hochgreb

Dr. William Hofmeister

Prof.George M. Homsy

Dr. Wesley C. Hymer

Dr. Marylou Ingrain

Dr. Ulf E. Israelsson

Department of Physics

College of Natural Sciences

University of Texas, Austin

Austin H"iX 78712

Office Ph: 512-471-3960 Fax: 512-471-9637 ..................................... !76

Department of Mechanical Engineering

Universityof Colorado

Campus Box 427

Boulder, CO 80309-0427

280 Office Ph: 303 492- 5092 Fax: 303 492-2863 .........................................

Department of Mechanical Engineering

Massachusetts Institute of Technology

77 Massachusetts Avenue 3-169

Cambridge, MA 02139

OfficePh: 617 253-0927 Fax: 617 253-5981 ...................................... 2.82

Department of Materials Science & Engineering

Vanderbilt University

Box 6309, Station B

Nashville, TN 37235

Office Ph: 615-322-7311 Fax: 615-343-0466 ..................................... 544

Department of Chemical Engineering

Stanford University

Stanford, CA 94305

OfflcePh: 415 723-2419 381

Department of Biochemistry & Molecular Biology

Pennsylvania State University

University Park, PA 16802

Office Ph: 814-865-2407 Fax: 814-865-2413 ...................................... 29

Huntington Medical Research Institute

99 North El Molino Avenue

Pasadena. CA 91101-1830

Office Ph: 818 795-4343 Fax: 208

818 795-5774 ..........................................

Jet Propulsion Laboratory

Mail Stop 125-112

4800 Oak Grove Drive

Pasadena. CA 91109-8099

Offlce Ph: 818 354-9255 Fax: 818 393-6383 .............................. _?_:._?_

anotageing eDge tHOU eeteeueoeeenueeau nooenue,eaneottetlm noaeel notH nototo eo| ooo| o| oot t oooot | ot oot oto to oOHO|Oat OOt O0notOO anot Ot t OeglaDOH gilanot gait eOto H|e O goot OI t Oaeo!. ooH O Hnot ! not OHnoto | ODe|o O too t et oooHooHeoe noDonot at OO0ooa to ! notO OOH;Oa tot* ooooooommmo

C-13
Appendix C: MSAD Program n FY1994 Principal Investigator Index

_K_j"_Nn_e_0_i_M_a_oo_o|t_a_o_to_t_!_o_Q_o_ooHo_o_oooooot_oHo_*_I_tato_o_o_oo_o_o_o|_t ,moon uotaooono|aol!t |a oooattt.tommtom,o|ooat|a.,Imn ,mtto|oonoo,mtamotooooomoootomooooototoattgtogteatttot'

Dr. Kenneth A. Jackson

Prof. Donald T./acobs

Prof. David Jasnow

Dr. I. M./essup

Dr. William L. Johnson

Dr. K. Kailasanath

Dr. Eric W. Kaler

Dr. Mark A. Kasevich

Arizona MaterialsLaboratory

Department of Materials Science & Engineering

Universityof Arizona

4715 East Fort Lowell Road

Tucson, AZ 85712

Office Ph: 602-322-2981 Fax: 602-322-2993 ..................................... 5,4.6

Physics Department

The College of Wooster

Wooster, OH 44691

Office Ph: 216 263-2390 180

Department of Physics and Astronomy

Universityof Pittsburgh

Pittsburgh, PA 15260

39O OfflcePh: 412 624-9029 Fax: 412 624-9163 .....................................

Associate Professor

Department of Surgery

Suite 3A

New England Deaconess Hospital

110 Francis Street

Boston, MA 02215

Office Ph: 617 632-9817 Fax: 617 _3_ 7a_4 211, 213

___- .... ,...............................,..........

Department of Materials Science

Mail Code 138-78

California Institute of Technology

Pasadena, CA 91125

Office Ph: 818-395-4433 Fax: 131 818-795-6132 .....................................

Laboratory for Computational Physics

and Fluid Dynamics

NRL Code 6410

Naval Research Laboratory

Washington, DC 20375

Office Ph: 292 767-2402 Fax: 202 767-4798 ...................................... _

Department of Chemical Engineering

Colburn Laboratory

University of Delaware

Newark, DE 19716

Office Ph: 302 831-3553 .........................................................3.9.2

Department of Physics

Stanford University

Stanford, CA 94305

Office Ph: 415-725-1311 Fax: 415-723-9173 ..................................... 1.8.2

t|eemNnNml*emmemm_tH_wemteeoueeHeeeeet tot teem teem eraeel eel tee too mmme *erato mtim to t tea t t a t ma te t mt t t o a t t * t t| t t e t ma t t, t to e t t met me t e e e o e tea. t t mme mtee tee teem teem tea n leeltee tee tee t t t t t t o eto t tin leo tea to e tee to mtie.o eel emit el t t_teettnt|t

C-14
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

oI I II I oil I I I t M I oI I t J| iI i I m ooa t ooill I oII OI atol * o, It, i o, ill J, ,,, o,, o,, o,,,, i _, ol, i, oi oo, .,,, O, t o,,, * ,, o, i Oil o, oo, oo, o, oo,,, go,, I,. oooI, oo, o,, o,, olit,, O, * OI, O, Ol, *, t O, O, OO, * II O, O, *, q*,'' O,, O, O, t 0OI t O, OOII, O,t. OOmO* t tg * I OIeO0| t aIOI Ira n I OO0|tlIO

Dr. Takashi Kashiwagi

Dr. Mohammad Kassemi

Prof. Michael J.Kaufman

Prof. Robert E. Kelly

Prof. Kenneth F. Kelton

Prof.Jungho Kim

Dr. John H. Konnert

prof. Joel Koplik

Center for Fire Research, Building and Fire Research Laboratories

National Institute for Standards and Technology

Building 224, Room B258

Gaithersburg, MD 20899

OfflcePh: 301 975-6699 Fax: 301 975-4052 ................................. .59:.2.88

NASA Lewis Research Center/Ohio Aerospace Institute

MS 1105-1

21000 Brookpark Road

Cleveland, OH 44135

Office Ph: 216 433-5031 Fax: 216 433-5033 ............................... 3.9.4.:.5..4.8.

Department of Materials Science & Engineering

University of Florida

201 Rhines Hall

Gainesville, FL 32611-2066

Office Ph: 904-392-6662 Fax: 904-846-6359 ..................................... 550

School of Engineering and Applied Science

University of California, Los Angeles

408 Hilgard Avenue

Los Angeles, CA 90024-1597

Office Ph: 310 825-5489 Fax: 310 206-4830 ...................................... 396

Department of Physics

Box 1105

Washington University,

One Brookings Drive

St. Louis, MO 63130

St. Louis

OfflcePh: 314-935-6228 Fax: 314-935-6219 .............................. _:._

Department of Engineering

University of Denver

2390 S. York Street

Denver, CO 80208

OfflcePh: 303 871-3816 Fax: 303 R71 4450 398 _ _- __. .......... ,,,,,.,,, ....... ,o,..,.,.°,°,.,,

Laboratory for the Structure of Matter

Code 6030

Naval Research Laboratory

4555 Overlook Avenue S.W.

Washington, 13(? 20375-6000

Office Ph: 202-767-3267 Fax:

216

202-767-6874 ..........................................

Department of Physics, Levich Institute

City College of The City University of New York

Convent Avenue & 138 th Sxreet

New York, NY 10031

OfficePh: 212 650-8162 400 .....,...**..,..,...,o ....... ..°.° ...... .,...°... ..... ..**....°.,......
Appendix C: MSAD Program m FY1994 Principal Investigator Index

D*| |_t0eOUe0Mee|NOet_tN4et_,t_e4teNttOU*HOOa J*O * O* * |H 0O, t O*0*O 0*a DOO.*no n * t *t to t * o t t olt ** Ors, 0*,*** tea .** ,*t t*. ** * * * *O* * * to* t* t | t * *, ot tol t *, t on t H to, t t a t M t t i t t *o |t s o* * It o tot * * ** lot t * * * i oa t * o o, o o * * to * o o, *a t oa t** too o_n*oou t* a tot,

Prof. Jean N. Koster

Prof. Sindo Kou

Prof. William B. Krantz

Dr. Shankar Krishnan

Prof. Jerry C. Ku

Prof.Douglas A. Kurtze

Prof. Richard T. Lahey

Dr. David J. Larmn" Jr.

Department of Aerospace Engineering Sciences

Campus Box 429

University of Colorado, Boulder

Engineering Center

Boulder, CO 80309-0429

Office Ph: 303 492-6945 Fax: 4Q2 2_25 89, 402 ----" .... .,.....,.o.H.o.. ,.*,.*.H*.,,,....,.*OHH.*,O.

Department of Materials Science and Engineering

University of Wisconsin

1509 University Avenue

Madison, WI 53706

Office Ph: 608 262-0576 Fax: 608 262-8353 ..................................... .4.0..4.

Department of Chemical Engineering

Campus Box 424

University of Colorado

Engineering Center, ECCH 1-43

Boulder, CO 80309-0424

Office Ph: 303-492-7050 Fax: 303-492-4341 ...................................._

Containerless Research. Inc.

910 University Place

Evanston, IL 60261-3149

Office Ph: 708 467-2678 Fax: 708 467-2679 ..................................... ..5.5..7.

Department of Mechanical Engineering

Wayne State University

5050 Anthony Wayne Drive

Detroit. MI 48202

Office Ph: 313 577-3814 Fax: 313 577-3881 ............................... 2.9.1.:.2.93

Department of Physics

North Dakota State University

SU Station, Box 5566

Fargo, ND 58105-5566

Office Ph: 701 231-7048 560 Fax: 701 231-7088 ...........................................

Nuclear Engineering and Engineering Physics

Center for Multiphase Research

Rensselaer Polytechnic Institute

Troy, NY 12180-3590

OfflcePh: 518 276-8579 Fax: 518 276-3055 ...................................... 4.0.6

Grumman Research & Development Center

A01-026

Northrop-Gnnnman Corporation

Bethpage, NY 11714-3580

Office Ph: 516-575-4896 Fax: 516-346-3670 ..................................... 133

m_:_`_--_:_-_._--_-_j_?_-_?f_|omm_4m|mtumtm_|_tt_ott_ttn_N_Hoett_|_$_e_to_$*_|_t_t_t_!!_*_t_g_*_tt|*_u_tt_H_ttt|*_*uu_|nH_|_*_N_tt_tNt_tttettutn_t

C-16
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

! | |H |oooJa lla |ooaeta naoltooolooa Ioa ,,,lira *oloolo wo* o io u a ou o_a o. Ha o |oo i |* | o* | o*| a* i a oo oo oo. ool ,to i_* |a * t u* i o| | o o o o i *lo* i o i i u u* ii* o o i * i o i *t ill n• o I*. m*. * ma * H* I o*I 11 * u a o o a o o a a o I a• I I o I a o o o mI o o * |o * I o a *. * o oo I o I I oI *o a * ot o Hoam** m II* m 0Oa

Prof.Chung K. Law

Dr. L. G. I.e_

Dr. Sandor L. Lehoczky

Dr. David T. Leighton

Dr. Peter I.Lelkes

Prof. Abraham M. Lenhoff

Prof.Moises Levy

Prof.A. Liakopoulos

Department of Mechanical and Aerospace Engineering

Princeton University

Engineering Quadrangle

Princeton, NJ 08544

OfflcePh: 609 258-5271 Fax: 609 258-6233 ...................................... 294

Department of Chemical and Nuclear Engineering

University of California, Santa Barbara

Santa Barbara, CA 93106

Office Ph: 805 893-8510 Fax: 805 893-4731 ...................................... 4.0.8.

Crystal Growth & Solidification Branch

Microgravity Science & Applications Division

ES75

NASA Marshall Space Flight Center

Marshall Space Flight Center. AL 35812

Office Ph: 205-544-7758 Fax: 205-544-8762 .............................. 1.371.139

Department of Chemical Engineering

University of Notae Dame

South Bend, IN 46556

OfficePh: 219-631-6698 Fax: 219-631-8366. 411

,, .... , ..................................

Laboratory of Cell Biology,

Sinai Samaritan Medical Center

Box 342

University of Wisconsin Medical School

945 North 12th Street

Milwaukee, WI 53201-0342

OfflcePh: 414 283-7753 Fax: 414 283-7874 ...................................... 2.18

Center for Molecular & Engineering Thermodynamics

Department of Chemical Engineering

University of Delaware

Newark, DE 19716-3119

OfficePh: 302-831-8989 Fax: 302-831-4466 ..................................... 223

Physics Department

University of Wisconsin, Milwaukee

Milwaukee, WI 53201

Office Ph: 414 229-4168 Fax: 414 229-5589 ...................................... _._.[

Department of Mechanical Engineering

Lehigh University

Bethlehem, PA 18015-3085

412 OfflcePh: 610 758-4929 Fax: 610 758-6224 ...........................................

a|l,,#eNeReueNIoUg0OnomM_0HemNeq_p|q0oeeeuell melDeDliD eei o| eel |el lea eu|e I10 eeoal eaeoql Doelie De| _o eooei * eo| oi oill o Dogleo oee| lit e* eeuloa| Inl e| ea| o| II OeII e| eo| I oI oI oeOeI eI elea eI Oo| oe* OoDOqe!Oe o| * ! OOt oI I l qeIO* OooDo* i o! l I o|Oeeeeteewle _o* eee_oe Doe i

C-17
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

Do6NH_eo_|ooo_o_no6|66|ou_oooa¢olooloJe_i6ooool JTooooo,ooDoa J4,ooooDlaOOl Juo....ie.i...o.ooae.|eo,o.,,o.i.uo,I.IIo_lo_lo,,o,ooDo, JO..,.G,O,.TIDOIDJa.DoO.,I.O4O,O...ID|,.,I"O'"O'""''"O'O"O|'OI JOI..OO.,..,..I..OI..O,.OIOOTOOI,"

Prof. Sung P. Lm

Prof. John A. Lipa

Prof. Jing Liu

Dr. Thomas A. Lograsso

Prof. Sudarshan K. Loyalka

Dr. Daniel W. Mackowski

Prof. Charles Maldarelli

Prof. Efstratios Manousakis

Department of Mechanical and Aeronautical Engineering

Box 572.5

Clarkson University

Potsdam, NY 13699-5725

Office Ph: 315 268-6584 Fax: 315 268-6438 ...................................... .4.!.3

Department of Physics

Stanford University

Stanford, CA 94305-4060

Office Ph: 415 723-4562 Fax: 415 723 8451 17, 19, 184 - ..,,,.,., ........ ,,,oo,*,ooo,,, ..... ,.,,...

Department of Physics

California State University, Long Beach

1250 Bellflower Boulevard

Long Beach, CA 90840

415 Office Ph: 310 985-4013 Fax: 310 985-7924 ...........................................

Institute for Physical Research & Technology

Iowa State University

109 Metals Development Building

Ames, IA 50011

Office Ph: 515-294-8425 Fax: 515-294-8727 • oo ,,oo oo,,,,o,,,,,,,,,, ,Hoo,,,,,°,,,,,,o 563

Particulate Systems Research Center

0039 Engineering Complex

University of Missouri, Columbia

Columbia, MO 65211

Office Ph: 314 882-8366 Fax:

417

314 882-2490 ..........................................

Assistant Professor, Department of Mechanical Engineering

College of Engineering

100 Rarnsey Hall

Auburn University

Auburn University, AL 36849-5341

Office Ph: 205-844-3334 Fax: 205.844-3307 ..................................... .565

Levich Institude & Department of Chemical Engineering

The City College of CUNY

Covent Avenue at 138th Street

New York, NY 10031

Office Ph: 212 650-8160 Fax: 212 650 6835 ...................................... .4.!9

Department of Physics

Florida State University

318 Keen Building

Tallahassee, FL 32306-4052

OfflcePh: 904 644-3713 Fax: 904 644-8630 .....................................!._

emqHHlUl4eIceweRe_o_onu,I._I0moNee e_elu eel, oeeenueeq_oooelog o6_ol oel mooool ooei ooaIo a|e o|oa i oa ! oaoooooooM ooi ooamooI oaIoo ooo. ooea moa nooooooemoeoooemoeoooBoomoooo, o|oa | oo,lea moomet Die nolooooogoeeoo, Io, oI e., o,, mo. noei oa |o a! 61utooloH elunJJula.ou i

C-18
AppendixC:MSADProgram-- FY1994 Principal Investigator Index

o_____|_oo_oo_oo_oooooa_oo|o___o_o_o_oo_o___aDoG_*___ao_aom_o|o__o||I__oa_o_ooo_oo_o_oo____o_n__aIIaooo_ao_aoo__oo_o_6!o_oo_oai_oaooa_i____*_a___o_ allloloo naola ooololoa•l aoiolooloool 0|Ialb0011IIIIO0100talI011101DOlDO*0010010IaO01004OBIOOO01'0"

Prof. Humphrey J. Marls

Prof. Philip L. Marston

Prof. l.on J. Mathias

Prof. Bernard J. Matkowsky

Prof. David H. Matthiesen

Dr. Richard J.Matyi

Prof. T. Maxworthy, Ph.D.

Prof.Mark J. McCready

Dr. Paul J.McGirm

Physics Department

Brown University

Providence, RI 02912

188 OfflcePh: 401 863-2185 Fax: 401 863-2024 ..........................................

Department of Physics

Washington State University

Pullman, WA 99164-2814

OfflcePh: 509 335-5343 Fax: 509 335-7816 ............................... 2.96:..4.2.1.

Department of Polymer Science

University of Southern Mississippi

Southern Station Box 10076

Hattieshurg, MS 39406-0076

Office Ph: 601-266-4868 Fax: 601-266-5504 ..................................... _

Department of Engineering Sciences of Applied Mathematics

Northwestern University

Evanston, IL 60208

298

OfflcePh: 708 491-5397 Fax: 708 491-2178 ...........................................

Materials Science and Engineering Department

Case Western Reserve University

10900 Euclid Avenue

Cleveland, OH 44106

Office Ph: 216 368-1366 ......... 141, 142, 144 °,°.,°, °..°...°°°,°..,....°°°,, ..,.°°.,.,.°°,°,..°°....o°°,-..

Department of Materials Science & Engineering

University of Wisconsin, Madison

1500 Johnson Drive

Madison, WI 53706

OfficePh: 608-263-1716 Fax: 608-262-8353 571 .°... .... °......,.°...., ............°...°.

Department of Aerospace Engineering

University of Southern California

854 W. 36th Pl., RRB 101

Los Angeles, CA 90089-1191

Office Ph: 213 740-0481 Fax:

573 213 740-7774 ...........................................

Department of Chemical Engineering

University of Notre Dame

182 Fitzpatrick Hall

Notre Dame, IN 46556

423

Office Ph: 219 631-7146 .......................................................................

Department of Chemical Engineering

University of Notre Dame

Notre Dame, IN 46556

OfflcePh: 219-631-6151 Fax:

574

219-631-8366 ..........................................

_'_M_|_oon_N_no_H_t_|uoo_m_oa|o_o_o_o_o_o_|_oa_o_|oo|o_|_a j oaoo_Io|D_|_|a_o_Bo_|_o_|_t|g_o_It_o_a_o_o_|_o_'_o_'o_D_a_oae_oo_Do_|o_ J0|II00D_alIII|III00mOlDI011OIO||OlDIIDIIIla Jlal

C-19
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

|eolte Doaooeu wea ion mssooog JJl ion oososo| meg s o | so os w|a i o i o o a | o o iJ ost i s.*oo *el *oo* s oo wol o o o. ooo a *ol * woo Doa H * *ea isa oolo s | t Joa oaa J Ra o lel o o | .m s o so o t| | oGo _o fo* Da o la o _ ao _o o s _ a * I _ * _ H s o o o_o _t u o I o o s u o o o oo o t s o *o_oo s oa H| so o oo**o_sooso_ oooo_aooooou

ProL Gareth H. McKinley

Prof.J. T. McKinnon

Dr. Alexander McPherson, Jr.

Prof. Eckart H. Meiburgj Ph.D.

ProL Suresh Menon

Prof. Herman Merte, Jr.

ProL Horst Meyer

Dr. William V. Meyer

ProL John J. Moore

Division of Applied Sciences

Harvard University

Pierce Hall, Room 316

Cambridge, MA 02138

OfflcePh: 617 496-5167 Fax: 617 495-9837 ....................................... _A

Department of Chemical Engineering and Petroleum Refining

Colorado School of Mines

Golden, CO 80401

Office Ph: 303 273-3098 Fax: 303 73-3730 ....................................... 3.00

Department of Biochemistry

Room 2466, Boyce Hall

University of California, Riverside

Riverside, CA 92521-0129

Office Ph: 909-787-5391 Fax: 909-787-3790 ...................................... _

Department of Aerospace Engineering

University of Southern California

846 W. 36th P., RRB 101

Los Angeles. CA 90089-1191

Office Ph: 213 740-5376 Fax: 213 740-7774 ...................................... _2_

School of Aerospace Engineering

Georgia Institute of Technology

Atlanta. GA 30332-0150

302 Office Ph: 404 853-9160 Fax: 404 894-2760 ...........................................

Mechanical Engineering Department

University of Michigan

Ann Arbor, MI 48109

OfflcePh: 313 764-5240 Fax: 313 747-3170 ................................. _:._

Department of Physics

Duke University

Durham, NC 27708-0305

Office Ph: 919 660-2520 Fax: 919 190 192 660-2521 ................................... : ......

Ohio Aerospace Institute

MS 105-1

NASA Lewis Research Center

21000 Brookpark Road

Cleveland, OH 44135-3191

OfficePh: 216 433-5011 639 Fax: 216 433-5033 ...........................................

Department of Metallurgical and

Materials Engineering

Colorado School of Mines

Golden, CO 80401

Office Ph: 303 273-3770 Fax: 303 273-3795 ............................... .3..04..:.578

l lllglieeHItllllllllglllnlNlllllltHtlII lieU I lltII Ii i I In IUUlUll * Ill t I 1 Ill I1! *tl n non i ltl it* ell it i ill ItllII I I OI Ill I* I III Ill I It! III I *! I *! I I I I II It I * *11 ! I I I I I .I l I* * Il * I SI *I I ! I I I! * II I I I I* * I I I I e I II I II * I I I I I lIIIIIFIIIIHIIItIIII*tl *

C-20
AppendixC:MSADProgram-- FY1994 Principal Investigator Index

ii i a i i .I i .i i i i iiI i | I i i I i i | i i I |11111111,. I. i i i i i o i *.. i. i * i. i. Di. i i e | M* |i i., i i 11 o. * D.ill i 14111. i 161., i,. mi I i o ,. ii o,, b, * D, i. i * i ... i i * o t * o o i ol g i Ii i I i i i i i i i. | I i 141.16116 o io i i i i ii i * i o i i, i i i i i i i* J i i 161 J ii i i i. i IG i ii i o i i i i * i i _ i *o i. I ii ill i i i i |11 iii i io * i

Prof. Allan S. Myerson

Prof. Ranga Narayanan

Prof. G. P. Neitzel

Dr. James R. Norris

Prof. Simon Ostrach

Prof. A. G. Ostrogorsky

Dr. Witold Palosz

Dr. Bernhard O. Palsson, Ph.D.

Head. Department of Chemical Engineering

Polytechnic University

Six Metrotech Center

Brooklyn, NY 11201

OfflcePh: 718-260-3620 Fax: 718-260-3776 ..................................... 5.80

Department of Chemical Engineering

University of Florida

227 Chemical Engineering Building

Gainesville, FL 32611

Office Ph: 904-392-9103 Fax: 582 904-392-9513 ..........................................

George W. Woodruff School of Mechanical Engineering

Georgia Institute of Technology

Atlanta, GA 30332-0405

426 Office Ph: 404 894-3240 Fax: 404 894-2291 ..........................................

Chemistry Division

Building 200, Room E133

Argonne National Laboratory

9700 South Class Avenue

Argonne, IL 60439

Office Ph: 708-252-3547 7 225 Fax: 08-252-9289 ..........................................

Department of Mechanical & Aerospace Engineering

418 Glennan Building

Case Western Reserve University

10900 Euclid Avenue

Cleveland, OH 44106

96, 428 OfficePh: 216 368-2942 Fax: 216 368-6445 ...........................................

Department of Mechanical Engineering,

Aeronautical Engineering, & Mechanics

JEC 2026

Rensselaer Polytechnic Institute

Troy. NY 12180-3590

584 Office Ph: 518-276-6975 Fax: 518-276-6025 ..........................................

Senior Research Associate

ES75

National Research Council

Marshall Space Flight Center, AL 35812

Office Ph: 205-544-1272 Fax: 205-544-8762 ..................................... 5.8.6

Department of Chemical Engineering

HerbertH. Dow Building

Universityof Michigan College of Engineering

2300 Hayward

Ann Arbor, MI 48109-2136

228 Office Ph: 313 763-2090 Fax: 313 764-7453 ...........................................
Appendix C: MSAD Program nFY1994 Principal Investigator Index

o o *oaooooloo ioa Dol Joa ooa iooooo ou io a m oloo ioo o o o IH * _ oo i _ a o i a o; o i a a i o oo o o o oa a oea o | ao. o o I • .o. o .*; a * aJ o beo. o. o. i. ooo. o o a o oo a o6a Jooo o #a i moo | o i o|a o i ooo o o o t a in a o | o o oi a o I al o o o J o a o aa * o o oo o o Joa o. * o o o o oo ooo o oa o_ oo_ o. o_ooooo oon_oe noa oon oon aa

Prof. Chang-Won Park

Prof.Alexander Z. Patashinski

Prof. Jerome K. Percus

Prof. John H. Perepezko

Prof. David R. Poirier

Dr. Marc L. Pusey

Dr. Marc L. Pusey

Dr. Seth J. Putterman

Department of Chemical Engineering

University of Florida

227 Chemical Engineering Building

Gainesville, F-'L 32611-2022

Office Ph: 904 392-6205 Fax: 904 392-9513 ...................................... _._

Department of Physics and Astronomy

Northwestern University

2145 Sheridan Road

Evanston, IL 60208-3112

Office Ph: 708 467-2618 Fax: 708 491-9982 ...................................... _95

Courantlnstimte

New York Univ_si_

251MercerStreet

NewYo_,NY 10012

Office Ph: 212 998-3130 431

,..,,,,,,,,,,,,,,,....,,,,,,,,.,,,,......,,.,.,,.,,,,,,.,,,,,,, .... ,...

Department of Materials Science and Engineering

University of Wisconsin

1509 University Avenue

Madison, WI 53706

Office Ph: 608 263-1678 Fax," 608 262-8353 ............................... 5.87:.589

Department of Materials Science and Engineering

College of Engineering & Mines

University of Arizona

Tucson, AZ 85721

OfflcePh: 602 621-7492 Fax: 602 621-9291 ...................................... 59.1

Biophysics Branch

Microgravity Science & Applications Division

ES76

NASA Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

Office Ph: 205-544-7823 Fax: 205-544-1777 ..................................... 229

Biophysics Branch

Microgravity Science and Applications Division

ES76

NASA Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

Office Ph: 205-244-7823 Fax: 205-544-1777 ..................................... 6.4..1

Physics Department

University of California, Los Angeles

Los Angeles, CA 90024

OfficePh: 310 825-2269 Fax: 310 825-5668 ...................................... 433

IngllooHooootoloiiooogoolooanloogoooologllgoouool nolo o no no |; na noon in I otao an no ion! o n Io on ann on sa |oIIo_a_eo_;o_g_oga_|_ooI_o_o_oHo_o_o_I_aa_ooo_o_I_I_ooaooI_;_o_a_o_H_aa_gI_o_ou_nFI)_o_g_o_

C-22
AppendixC: MSADProgram-- FY1994 Principal Investigator Index

_aoI_IeIoH_oo_IeIDooIIoIIIIiH_ooI_oo_ooooo_6oooo_o_______o______________________________1________________o_____o____________o__!______4______________o_oo__oo___________ Jl,o,,,tOl*|,.o|.oo*,ooool JtlioooDooooooooIItOtoInuIoIIoltoGIIJIOIIIOlo,

Dr. Chandra S. Ray

Prof. Dennis W. Readey

Dr. Liya L. Regel

Dr. Won-Kyu Rhim

Prof. David C. Richardson

Dr. Michael B. Robinson

ProL Paul D. Ronney

Prof. Franz E. Rosenberger

Graduate Center for Materials Research

University of Missouri, Rolla

Rolla, MO 65401

OfficePh: 314-341-6432 Fax: 314-341-2071 ..................................... 593

Coors Professor of Ceramic Engineering

Department of Metallurgical and Materials Eng.

Colorado School of Mines

Golden, CO 80401

595 Office Ph: 303 273-3437 Fax: 303 273-3795 ...........................................

Research Professor of Engineering

International Center for

Gravity Materials Science & Applications

Clarkson University

Box 5700

Potsdam, NY 13699-5700

OfficePh: 315-268-7672 599 Fax: 315-268-3841 ..........................................

Jet Propulsion Laboratory

Mail Stop 183-401

4800 Oak Grove Drive

Pasadena, CA 91109

Office Ph: 818 354-2925 Fax: 818 3935039 601 ,, o*......*o..,,...,, ..,o°.,.,,,, o.,*.* .,o,

Department of Biochemistry

Box 3711

Duke University Medical Center

211 Nanaline Duke Building

Durham, NC 27710

OfficePh: 919-684-6010 Fax: 231 919-684-8885 ..........................................

Crystal Growth & Solidification Branch

Microgravity Sceince & Applications Division

ES75

NASA Marshall Space Flight Center

Marshall Space Flight Center, AT., 35812

Office Ph: 205-544-7774 Fax: 205-544-2176 ....................... .6.. .O4. :. .6..0.6.:. .6..0.7.

Department of Mechanical Engineering

OHE 430

University of Southern California

Los Angeles, CA 90089-1453

60, 307, 435 Office Ph: 213 740-0490 Fax: 213 740-8071 ...........................................

Center for Microgravity and Materials Research

Room M65

University of Alabama, Huntsville

Huntsville, AL 35899

145, 233 Office Ph: 205-895-6050 Fax: 205-895-6791 ..........................................

ai i I IIIIIIHIHIIlHIIIHII IIIIII IOIIlUlHII Ill Ill Ill I I I I OI I II O tI I II I I I I I IO I II I lit III I I I I I OII I I 11 OI I I I OI II I II I I Ol II I I I aiI I i i I oI i I I I I II * tI I I I I oI OI I I Ii i I I I I I I I t It I II IIll lifo III I I I I I oatO tOtel I I I oI Ol It * I11 II II I I I Ill I I I I to I Ill It I I IHIO Ill IOI I tO IN I

C-23
Appendix C: MSAD Program- FY1994 Principal Investigator Index

o, i i o i, a t 6, * | o * D6o * t * o | o a itn o tat oo o 61 o o o a t o a * o Qo; 8 o o o o * o a * Jl * i a * o o ot o o o o o Do, o o I, o a, I i, i a * I o o | o * IQ * | a o b a i oo, I o o |. o o o * o a, o a o o a * | i, | a * iI * _ I o | Do * o o * b I * to * Da * Da o mul ma o la o o o * I o o o i a, ti o mo o * _ o o | a * _ ao | 4o t o a,, o * o o o * to o o o a oo a o * o * Do o Do o oto to | t * o t Do *, o o• o *

Dr. Bruce N. Rosenthal

Prof.Daniel E. Rosner

Dr. Graham Ross

Dr. Howard D. Ross

Dr. Paul H. Rothe

Dr. Robert T. Rugged

Dr. Kurt R. Saeksteder

Prof. Satwindar S. Sadhal

NASA Lewis Research Center

21000 Brookpark Road

Cleveland, OH 44135

OfficePh: 216 ,133-5027 643

,,,.., ..... ,,,°,. ........... ,,,,°,,,**,,,,,, ...... ,,..,....,,**,,°,,*,,

Chemical Engineering Department

Mason Laboratory

Yale University

P.O. Box 2159. Y.S.

New Hav_, CT 06520-2459

Office Ph: 203 432-4391 Fax: 7 437 203 432- 232 ...........................................

Lockheed Missiles & Space Co.

O/92-05, B/260

3251 Hanover Street

Pal, Alto, CA 94304-1187

OfflcePh: 415 424-3488 Fax: 415 424-3315 ..................................... _

NASA Lewis Research Center

MS 500-115

21000 Brookpark Road

Cleveland, OH 44135

Office Ph: 216 433-2868 ............................................................. .63:.3.09...

Creare, Inc.

P.O. Box 71

Hanover, M-I 03755

Office Ph: 603 643-3800 440

Fax: 603 643-4657 ...........................................

The Boeing Company

P.O. Box 3707

Seattle, WA 98124-2207

Office Ph: 206 773-8908 441 Fax: 206 773-4946 ...........................................

NASA Lewis Research Center

MS 500-115

21000 Brookpark Road

Cleveland, OH 44135

Office Ph: 216 433-2857 315 Fax: 216 433-8660 ...........................................

Department of Mechanical Engineering

University of Southern California

Los Angeles, CA 90089-1453

Office Ph: 213 740-0492 Fax: 213 740-8071 ...................................... 443
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

,.oOlnaOOOlOOIleNOol0O6nolOO0Ol.eO j oooi_noo|_____________________________________________"________________________________ _________________________"_____________________________________________________"_______________o____o_o_|_a_6__"__a_

Prof. W. M. Saltzman

Prof. Ashok S. Sangani

Prof. Robert L. Sani

Dr. Dudley A. Saville

Dr. David W. Scharp

Prof. Benjamin D. Shaw

Dr. Frank G. Shi

Department of Chemical Engineering

Room 24, New Engineering Building

Johns Hopkins University

3401 North Charles Street

Baltimore, MD 21218

Office Ph: 410 516-8480 Fax: 410 516-5510 .......................................... 236

Department of Chemical Engineering

& Material Science

Syracuse University

Syracuse, NY 13244

OfflcePh: 315 443-4502 .................................................................. .446

Department of Chemical Engineering

University of Colorado

Engineering Center

ECCH 1-43. Campus Box 424

Boulder, CO 80309-0424

Office Ph: 303 492-5517 Fax: 303 492-434l ...................................... _

School of Engineering & Applied Science

Department of Chemical Engineering

Princeton University

The Engineering Quadrangle

Princeton, NJ 08540-5263

Office Ph: 609-258-4585 Fax: 609-258-0211 .............................. 101:...4.48

Department of Surgery

Box 8109

Washington University School of Medicine

4939 Audubon Avenue

St. Louis. MO 63110

OfficePh: 314 362-8320 Fax: 314 239 361-0426 ...........................................

Department of Mechanical, Aeronautical &

Materials Engineering

University of California, Davis

Davis, CA 95616-5294

Office Ph: 916 752-4130 Fax: 916 752-4158 ............................... 317:..4.50

School of Engineering

University of California, Irvine

916A Engineering Tower

Irvine. CA 92717-2575

Office Ph: 714-856-5363 Fax: 714-725-2541 ..................................... _.P_

eeel_Nla_loee(leeeneqbe Jl(llneueonneoe|eeeeoeqo_D| _ecee eu eu nooeeae$eeSoeeo eoenooecoo ee| ooge6a l eaal e0a*o 0aql(,luole etHee i oe | ooeeeelu en non nlH | ol a_eo eoea Dee|o oeooeo_in*oe cogeeo| Doe ei oe| ooei qeoqe! oaeoooeo* oaei aeeoa| eai oai Iae| oe| eeM eeI oa|ee Io| eeoeeoeI eeI n

C-25
AppendixC: MSADProgramm FY1994 Principal Investigator Index

_____n______o___Hi_i___u____H___no|o_gn______o________________|____________________I_______________ j_6_|_o_*_.._._I_o_._I_*.to*_o6_o_|0_t_mI'on_*Q_.mIont_n_o_R_w_

Dr. Peter Shirron

Dr. Joel A. Silver

Dr. Bhim S. Singh

Dr. N. B. Singh

Dr. Gregory T. Smedley

Prof. Marc K. Smith

Prof. Mitchell D. Smooke

Dr. Robert S. Snyder

MS 713

NASA - Goddard Space Flight Center

Greenbelt Road

Greenbelt, MD 20771-0001

Office Ph: 301 286-7327 Fax:

645 301 286-1702 ...........................................

Southwest Sciences, Inc.

1570 Pacheco Street, Suite E-11

SameFeo NM 87501

OfflcePh: 505 984-1322

320

Fax: 505 988-9230 ...........................................

NASA Lewis Research Center

MS 500-327

21000 Brookpark Road

Cleveland, OH 44135

Office Ph: 216 433-3321

451

Fax: 216 433-8660 ....................................

Westinghouse Electric Corporation

1310 Beulah Road

Pittsburgh, PA 15235

Office Ph: 412 256-1469 Fax: 147 412 256-1661 ...........................................

Jet Propulsion Laboratory

Mail Stop 278-01

4800 Oak Grove Drive

Pasadena, CA 91109

Office Ph: 818 354.0583

453

*ttttSt**St**lltltt**t*tttStttttttt*tl_'ttttt*t*ltt**ltOttttS*t*lt*t't*

George W, Woodruff School of Mechanical Engineering

Georgia Institute of Technology

Atlanta, GA 30332-0405

454 Office Ph: 404 894-3826 Fax: 404 894-2291 ...........................................

Dept. of Mechanical Engineering

Yale University

P.O. Box 2159 - Yale Station

New Haven, CT 06520-2159

Office Ph: 203 432-4344 Fax:

322

203 432-1054 ...........................................

Chief, Mierogravity Science & Applications Division

ES76

NASA MarshaLl Space Flight Center

Marshall Space Flight Center, AL 35812

34 Office Ph: 205-544-7755 Fax: 205-544-8762 ..........................................

et ogNtoeeweNu, otQmln_c4guoolNMu4lml.tnnRe mneeotxte;eto otint te mi**;mitemimi;mimimi e* to t t; ntmiamitql_*a; * * t * _ot * u* mi * * * o* mi.*a lumimimi;nit* nit; |*; mite|; aotl mitoo tee mitemnto tie re;tooto;too mitt eta nut to to ii otu m;otto;tom;too too no to! mitt |miomitimit omitl-It 14It I.nlt OlOtI_IS_M_NI4tnx

C-26
Appendix C: MSAD Program m FY1994 Principal Investigator Index

o_x_He_e|ee_e_ew|_e_o|e_ouooo_oooooIooo_o_o_i_eool_aI_1le_o_o_o_o_o_1_o_o_oo_o_o_o_oo_._|_ooo_o_I_G Jo, o..i.oooooooaloalu J_..oo,

ProL Frans A. Spaepen

Prof. Paul H. Steen

Prof. Doru M. Stefanescu

Dr. Donald M. Strayer

Dr. Stein Stum

Dr. Ching-Hua Su

Prof. R. S. Subrarnanian

Prof. Harry L. Swinney

Division of Applied Sciences

Harvard University

29 Oxford Street

Cambridge, MA 02193

Office Ph: 617 495-3760 Fax: 617 495-9837 ...................................... _0_

School of Chemical Engineering

Comeli University

Olin Hall

Ithaca, NY 14853-5301

Office Ph: 607 255-4749 Fax: 607 255-9166 ...................................... _

Department of Metallurgical & Materials Engineering

F301 Mineral Industries Building

University of Alabama

P.O. Box 870202

Tuscaloosa, AL 35487-0202

Office Ph: 205-348-1748 Fax: 205-348-8574 .............................. 1.49:.61.1

Jet Propulsion Laboratory

Mail Stop 233-200

4800 Oak Grove Drive

Pasadena, CA 91109-8099

OfflcePh: 818 354-1698 Fax" 818 393-4878 ...................................... 196

Department of Civil, Environmental & Architectural Engineering

Engineering Center OT6-26

University of Colorado

Campus Box 428

Boulder, CO 80309

Office Ph: 303-492-7651 Fax: 303-492-7317 ..................................... 103

Crystal Growth & Solidification Branch

Microgravity Science & Applications Division

NASA Marshall Space Flight Center

ES75

Marshall Space Flight Center, AL 35812

Office Ph: 205-544-7776 Fax: 205-544-8762 ..................................... !51.

Department of Chemical Engineering

Box 5705

Clarkson University

Po_dam. NY 13699-5705

OfflcePh: 315 268-6648 Fax: 315 268 6654 105, 459

__ - ..,,,°.,, ....... ,,,,,,* ...... , .............

Department of Physics

University of Texas, Austin

Austin, 'IX 78712-1111

OfficePh: 512 471-4619 461 Fax: 512 471-1588 ...........................................

_!_q_ge_m_e_maoe_aoomooou_o_o_e#_N_o_!_|_a_a_o_o_o_|o_!_!_o_o_o_oo_o_|o_|o_oa_boo_o_o_oo_o_||o_oo_o_b_o_oa_oo_oa_oo_o_|_o_ooa|o_o!_!!_!_!_o_

C-27
AppendixC:MSADProgram-- FY1994 Principal Investigator Index

.,.,ss,,s,nnos,to,,o,stisi,,.,s,,s.,s,,_l,s..,s|g,.*,se,,it _*Dt*"*_,DH_o_o_•_**_'_o_*H_•_H_H_H_e_*_,_""_H_u_"_t1_s_eI_m_sQ_I_so*_,_1_*_s_s_ss_*_os_t_s_t_to*_*

Dr. Julian Szekely

Dr. Frank R. Szofran

Prof. James S. T'ien

Prof. Saleh Tanveer

Dr. Robert L. Thompson

Prof. Penger Tong

Dr. John M. Torkelson

Prof. Grater Tryggvason

Department of Materials Engineering

Room 4-138

Massachusetts Institute of Technology

77 Massachusetts Avenue

Cambridge, MA 02139-4307

OfficePh: 617-253-3236 Fax: 617-253-8124 153, 613

,.,.°°.,.,°,., ........ ,,,,)...°.°*°°* .... •

Crystal Growth & Solidification Branch

Microgravity Science and Applications Division

ES75

NASA Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

155

OfficePh: 205-544-7777 Fax: 205-544-8762 ..........................................

Mechanical & Aerospace Engineering

415 Glerman Building

Case Western Reserve University

10900 Euclid Avenue

Cleveland, OH 44106

OfficePh: 216 358-4581 Fax: 216 358-6445 ................................. 66:.3.23

Department of Mathematics

Ohio State University

231 West 18th Avenue

Columbus, OH 43210-1174

OfficePh: 614 292-5710 7 463 Fax: 614 292-14 9 ..........................................

NASA Lewis Research Center

MS 500-102

21000 Brookpark Road

Cleveland, OH 44135

OfficePh: 216 433-3321 465

Fax: 216 433-8660 ...........................................

Oklahoma State University

Stillwater, OK 74078-0266

Office Ph: 405 744-5800 467

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Department of Chemical Engineering

Northwestern University

Evanston, IL 60208-3120

Office Ph: 708-491-7449 Fax: 708-491-3728 ..................................... 6.!5

Department of Mechanical Engineering

University of Michigan

2250 G. G. Brown Building

Ann Arbor, MI 48109

Office Ph: 313 763-1049 468, 617

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Appendix C: MSAD Program -- FY1994 Principal Investigator Index

a i o* oolooleol l e_ Go i* o oo_ u_ o_oa o oa o o4 g |u o o4I ool o o a o o g o i i o o o a oo a _ o a e o a o. o oa e l a o t a o Pa o Ja e ia o t o I aIta o J a i _g I t* aa i I i t o I o ta o Ia g | J 111 J e o a o o o o oo a o o o i ! 1 _ n a _ * IG_u o o o o a a o u a _ | I oi 11 * i a I | no t aI a ia 11111 J o o o o i ag o Ia g oJ * g o o a o 11 a g n a o o 11 o n a o u ao o o o o o I o a a o la ooa o I i

Prof. John Tsamopoulos

Dr. David L. Urban

Prof. Arvind Varma

Prof. Jorge Vifials

Dr. Martin P. Volz

ProL Peter W. Voorhees

Prof. Taylor G. Wang

Dr. Keith B. Ward

Department of Chemical Engineering

State University of New York. Buffalo

507 Furnas Hall

Buffalo, NY 14260

OfficePh: (716) 645-6229 Fax: 716-645-3822 ..................................... _._Q

NASA Lewis Research Center

MS 500-115

21000 Brookpark Rd.

Cleveland, OH 44135

OfficePh: 216 433-2835 Fax: 216 433-8660 ...................................... ?._

University of Notre Dame

Nortre Dame1 IN 46556

OfflcePh: 219 631-6491 Fax: 219 631-8366 ...................................... _._

Super Computer Research Institute

Florida State University

444 Science Center Library

Tallahassee, FL 32306-4052

Office Ph: 904 644-1010 Fax: 472 904 644-0098 ...........................................

Crystal Growth & Solidification Branch

Microgravity Science & Applications Division

ES75

NASA Marshall Space Flight Center

Marshall Space Flight Center. AL 35812

Office Ph: 205-544-5078 Fax: 205-544-8762 ..................................... 6.!8

Department of Materials Science and Engineering

Northwestern University

2145 Sheridan Road

Evanston, IL 60208-3108

OfflcePh: 708 491-3537 Fax: 708-491-7820 ..................................... 6.20

Center for Microgravity Research & Applications

Vanderbilt University

Box 6079, Station B

Nashville, "IN 37235

Office Ph: 615 343-6965 Fax: 615 343-8730 ............................... 1.07:.474

Laboratory _r _e Structure of Matter

Code 6030

Naval Research Laboratory

Washington, 13(2 20375-5000

Office Ph: 202-767-2735 Fax: 7 7 7 241 202- 6 -68 4 ..........................................
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

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ProL Peter C. Wayner, Jr,

Dr. Richard J. Weber

Dr. Karen J. Weiland

Dr. David A. Weitz

ProL Indrek S. Wichman

Dr. Heribert Wiedemeier

Dr. John M. Wiencek

Dr. R. A. Wilkinson

Prof. Forman A. Williams

Isermann Department of Chemical Engineering

Rensselaer Polytechnic Institute

Troy, NY 12180-3590

OfflcePh: 518 276-6199 Fax: 518 276-4030 ...................................... 476

Containerless Research, Inc.

910 University Place

Evanston, IL 60201-3149

Office Ph: 708 467-2678 Fax: 708 467-2679 ...................................... _

MS 110-3

NASA Lewis Research Center

21000 Brookpark Road

Cleveland. OH 44135

OfficePh: 216 433-9065 Fax: 216 433-3793 ...................................... _

EXXON Research and Engineering Co.

Route 22 East, Clinton Township

Annandale, NJ 08801

OfficePh: 908 730-3536 Fax: 908 730-3042 ...................................... !O9

Department of Mechanical Engineering

Michigan State University

East Lansing, MI 48824

OfflcePh: 517 353-9180 Fax: 517 353-1750 ...................................... 329

Department of Chemistry

211 MRC

Rensselaer Polytechnic Institute

Troy, NY 12181

Office Ph: 518-276-8444 Fax: 518-276-8554 ..................................... !5.7.

Department of Chemical & Biochemical Engineering

University of Iowa

Iowa City, IA 52242

Office Ph: 319-335-1400 Fax: 319-335-1415 ..................................... 243

NASA Lewis Research Center

MS 500-102

21000 Brookpark Road

Cleveland, OH 44135

OfflcePh: 216 433-2075 Fax: 216 433-8660 ....................................... 2.1

Department of Applied Mechanics

University of California, San Diego

Engineering Science, B-010

La Jolla, CA 92093-0411

Office Ph: 619 534-5452 ...................................................... 69:..3.30:.3.3.1.

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C-30
Appendix C: MSAD Program m FY1994 Principal Investigator Index

_It_|_io_oI|_oaI_|e_m|_Dono_I_HIoo_0o_|ouoa_|_I!Io|io_o_o"ooo_H_o_ J tooooolooaolaolgoloHaolaonaolooJoooaoloiDooooooolot ao_ooouolunuoo_o_|oaolaoua_oloo*_ao|a_oaoo_oooaooaoj_oooo_ooooo|oo JaOO_oDao_ooooo*o_O.OOOO.O_OOO

Dr. W. W. Wilson

Dr. Michael Winter

Mr. William K. Witherow

Prof. August F. Witt

ProL Larry Witte

ProL M. G. Worster

Dr. Xiao-lun Wu

Dr. Jiarm C. Yang

Department of Chemistry

Mississippi State University

Drawer CH

Mississippi State, MS 39762-5613

OfficePh: 601-325-3584 Fax: 601-325-1618 ..................................... 246

United Technoligies Research Center

M.S. 90

East Hartford, CN 06108

Office Ph: 203-727-7805 Fax: 203-727-7911 ..................................... _._

Biophysics Branch

Microgravity Science and Applications Division

ES76

NASA Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

OfficePh: 205-544-7811 Fax: 205-544-2102 ..................................... 650

Ford Professor of Engineering

Department of Materials Science & Engineering

Room 13-4134

Massachusetts Institute of Technology

77 Massachusetts Avenue

Cambridge, MA 02139-4307

OfflcePh: 617-253-5303 Fax: 617-253-5827 ..................................... 624

Department of Mechanical Engineering

University of Houston

4800 Calhoun Road

Houston, TX 77204-4792

OfficePh: 713 743-4501 .................................................................. !.!0

Department of Engineering Science

and Applied Mathematics

Northwestern University

633 Clark Street

Evanston, IL 60201

OfficePh: 708 491-3345 478

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Department of Physics & Astronomy

University of Pittsburgh

Pittsburgh, PA 15260

OfflcePh: 412624-0873 Fax: 479 412-624-9163 ..........................................

Fire Sensing and Extinguishment Group

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899

OfflcePh: 301 975-6662 Fax: 301 975-4052 ...................................... 3.35

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C-3 1
Appendix C: MSAD Program -- FY1994 Principal Investigator Index

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Prof.AbdelfattahZebib

Mr. Frank R. Zimmerman

Dr. Charles F. Zukoski

Department of Mechanical and Aerospace Engineering

Rutgers University

P.O. Box 909

Piscataway, NJ 08855-0909

Office Ph: 908 445-2248 Fax: 908 932-5313 ...................................... 481

Metals Processes Branch

Metallic Materials & Processes Division

EH25

NASA Marshall Space Flight Center

Marshall Space Flight Center, AL 35812

Office Ph: 205-544-4958 Fax: 205-544-0212 ..................................... .651

Department of Chemical Engineering

114 Roger Adams Laboratory

University of Illinois

600 South Matthews Su'eet

Urbana, IL 61801

Office Ph: 217-333-5076 Fax: 217-244-8068 ..................................... _

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C-3 2

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