bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Homogeneous Nucleation in Planar Dynamic Discrete Dislocation Plasticity
Authors: Gurrutxaga-Lerma Benat , Balint Daniel S. , Dini Daniele , Eakins Daniel E. , Sutton Adrian P.
Published: April 2015

Homogeneous nucleation of dislocations is the dominant dislocation generation mechanism at strain rates above 108 s−1; at those rates, homogeneous nucleation dominates the plastic relaxation of shock waves in the same way that Frank–Read sources control the onset of plastic flow at low strain rates. This article describes the implementation of homogeneous nucleation in dynamic discrete dislocation plasticity (D3P), a planar method of discrete dislocation dynamics (DDD) that offers a complete elastodynamic treatment of plasticity. The implemented methodology is put to the test by studying four materials—Al, Fe, Ni, and Mo—that are shock loaded with the same intensity and a strain rate of 1010 s−1. It is found that, even for comparable dislocation densities, the lattice shear strength is fundamental in determining the amount of plastic relaxation a material displays when shock loaded.
An Overview of Gas Turbine Power in the People’s Republic of China
Authors: Auld Andrew J.
Published: April 2015

Many people look upon the People’s Republic of China as an area of great potential for industrial gas turbines. This paper reviews the present status of gas turbines in place in China and also comments on manufacturing facilities planned and in place.

The author’s overview is based upon visits to a number of turbine plants on Mainland China and interviews with plant officials and engineering personnel.
The Application of an 82.5% Efficient Co-Generation Facility
Authors: Bosscher D. D. P. , Jones A. S. , Stiffler J. A.
Published: April 2015

This paper highlights the results of the co-generation study and construction program of Hollandia-Coevorden, a paperboard mill located in the Netherlands. Selection of equipment based on an analysis of excess air ratio, along with a description of the installation, is presented. Operational experience, including availability and economic benefits, is reviewed, reinforcing their selection, which was based on the principles of minimal maintenance and operational simplicity. An improved performance program is also discussed. The program resulted in a 3.0 MW co-generation facility with a thermal efficiency of 82.5%.
A Data-Logging and Performance Analysis System for Application to Industrial Gas Turbines
Authors: Timperley S. , Smith M. K. D.
Published: April 2015

Ruston Gas Turbines is a manufacturer of industrial gas turbines. Present models are in the power range 1.3 MW to 6.5 MW, and engine testing is performed on two separate sites, one for acceptance testing of production engines, the other for development testing.
Conversion of JCP&L Gas Turbines From Oil to Oil and Gas Fuels
Authors: Bailey B. L. , Yosh D. F.
Published: April 2015

Rising oil prices and the availability of natural gas make a field conversion to dual fuel (oil and gas) economically attractive. Design requirements for the gas turbines as well as yard piping and equipment are discussed. Installation work is summarized and operating experience after about 1500 hours per unit on gas is discussed.
Certification of Mechanical-Drive Gas Turbine Packages for Installation in Hazardous Locations
Authors: McMullen J. C. , Dundas R.
Published: April 2015

It is becoming increasingly more difficult to obtain local jurisdictional approval for the installation of gas turbines in hazardous locations. This is occurring because of changes to codes and standards, the reluctance of inspectors to make judgments on special equipment, and the requirements for third party certifications in countries other than the country of manufacture.

The Gas Turbine Division of General Electric Company has initiated a program to review, upgrade, and certify its mechanical drive product line for installation in hazardous locations. The special requirements and problems of the program, as well as its implementation, are discussed.
The Navy PATE Program: A Status Report
Authors: Greco L.
Published: April 2015

The Navy PATE (Propulsion Automatic Test Equipment) program was initiated in 1977 in an attempt to control the development, procurement, and implementation of computerized test equipment for testing Navy aircraft gas turbine engines and engine components. Software tools have been developed to enhance standardization of the use of the ATLAS language for engine test programs. The hardware systems delivered to fleet activities are all based on the Digital Equipment Corporation PDP 11/34 minicomputer. The philosophy utilized has been to add computer-based data acquisition systems as redundant systems to existing test cells. This paper describes the systems deployed to the fleet, the operating capabilities of these systems and the experience gained. Projections for potential applications of current and planned systems are also included.
Computer Systems: An Aid to the Development of Gas Turbine Engines
Authors: Schneider H.
Published: April 2015

This paper presents a concept as to the stepwise extension of computer-systems application by KHD Luftfahrttechnik’s engineering departments engaged in gas turbine engine development.

A base line system is in used today and criteria have been established to expand this into an efficient engineering tool.

Discussed are the principle conditions and targets including items such as cost effectiveness, data communications between different departments, programming, personnel training as well as data analysis and requirements for soft and hardware.
A Gasturbine as Emergency Propulsion Unit in a Liquid Sulphur Tanker
Authors: Riemersma J. W.
Published: April 2015

The liquid sulphertanker “Bearn” of the Societe Nationale Elf Aquitane was originally provided with one main propulsion engine. In view of the normal routes of the ship and the kind of cargo, the decision was taken not to rely on the diesel engine only but to convert the propulsion system into a CODOG (Combined Diesel Or Gasturbine) installation.

CODOG is not unknown, but mostly used on military or semi-military ships. These systems are designed for cruising on diesels for reasons of fuel economy and when higher power is needed the gasturbine is used. In this case the CODOG system is designed to ensure propulsion power in case of problems with the main engine. The problem with this installation was, that it had to be installed in an existing ship with very limited space available and no disturbance of the diesel engine propulsion system and ship’s construction was allowed.
Design of Shock-Free Compressor Cascades Including Viscous Boundary Layer Effects
Authors: Dulikravich George S. , Sobieczky Helmut
Published: April 2015

A computer code that generates shock-free transonic compressor cascade shapes while taking into account viscosity effects is developed. The mathematical model for the inviscid flow field is the full potential equation. The Kutta-Joukowski condition is satisfied by varying the free stream angle at downstream infinity. A boundary fitted computational grid of C-type is generated using a sequence of conformal mapping and nonorthogonal coordinate stretching and shearing transformations. The inviscid calculation is performed sequentially on up to four consecutively refined grids thereby accelerating the convergence of the solution process. The full potential equation is solved using a finite area technique and rotated, type-dependent finite differencing. Artificial viscosity of the first order is added in a fully conservative form. Shock-free cascade airfoil shapes are obtained using the fictitious gas concept of Sobieczky and the method of characteristics in the rheograph plane. Viscosity effects are incorporated via a boundary layer displacement thickness. The integral boundary layer code is based on Rotta’s turbulence model and assumes transition region of zero length.
The Impact of Three-Dimensional Analysis on Fan Design
Authors: Clemmons Daniel R. , Dodge Paul R. , Blackmore Walter L.
Published: April 2015

In the last few years, great strides have been made in the numerical simulation of flows in turbomachinery blade rows. Efforts began with the development of two-dimensional (2-D) solutions such as those of Katsanis, et. al., Dodge, Gopalakrishnan, and others. These solutions solved subsonic, and in some cases, transonic flows in a blade-to-blade plane. By proper use of these methods, much of the information previously obtainable only from cascade testing could now be computed. Although losses could not be directly calculated, Dodge and Serovy showed that inviscid deviation angles, minimum loss angles of attack, and relative ranking between competing blade shapes could be determined by analysis.
A Vortex Venturi for Reverting Antimisting Fuel Properties
Authors: Szetela E. J. , TeVelde J.
Published: April 2015

The level of degradation of antimisting fuel polymers such as FM-9 which must be accomplished in order to use antimisting fuel in existing engines may require the use of cavitation. The hydrodynamic shear produced by the collapse of vapor bubbles is capable of producing more splitting of polymeric molecules than mechanically-induced shear. A program has been carried out to investigate the possibility of using a cavitating venturi with rotating flow as a fuel reverter. This investigation included the effects of a swirl-inducing twisted tape upstream of the throat, inlet pressure, recovery pressure ratio and a pintle for varying throat area. A correlation of the data was produced, system concepts for using the vortex venturi were investigated and problem areas were delineated.
Aircraft Usage and Effects on Engine Life
Authors: Montgomery J. F. , Sewall T. R. , Batka J. J.
Published: April 2015

Factors which affect engine life include design practices, manufacturing processes, materials, engine installations, usage, and maintenance system practices. While engine life definition and management are dependent upon the development and organization of these factors, aircraft engine power usage is a major factor affecting engine life in field operations. This statement is based upon an improved understanding of engine usage as functions of aircraft characteristics and the nature of missions which are flown. Increasing amounts of data have been acquired in recent years that provide insights into the magnitude and variability of engine life for several aircraft systems.

This paper will compare aircraft usage and engine life relationships for representative aircraft systems. An outline of procedures used to evaluate engine usage and its effects shall also be presented.
A Stiff, Lightweight Machinery Baseplate on Three Spherical Supports
Authors: Potter Trevor
Published: April 2015

A study was carried out to develop a lightweight machinery baseplate for offshore applications. To prevent platform movement from affecting the machinery alignment, the baseplate was mounted on three bearings. Inherent stiffness, with significant weight saving over a conventional baseplate, was achieved by the use of a torque tube as the primary structural component.
The Effect of Blade Discretization on Resonant Turbine Blade Response
Authors: Sheng Chia-Fu , Mosimann John G.
Published: April 2015

The two methods currently used in industry to calculate blade resonant responses, the energy method and the transmissibility method, are discussed relative to accuracy and facility. Although identical in form for the ideal case, the methods differ in accuracy for practical cases depending on discretization, i.e., model lumped mass breakup fineness. For clarity, the equations for these two methods are derived for a Timoshenko beam and solved numerically for a beam with varying discretization. The results show resonant stress differences up to 30% for higher modes using limited but equal discretization, proving the practical superiority of the energy method over the transmissibility method by example as well as by theory.
The Industrial RB211-24 Gas Generator: Initial Experience in Service Offshore
Authors: Soinne P. E.
Published: April 2015

The Industrial RB211 gas generator is derived from the RB211 turbofan aero engine which in its various marks powers all Lockheed Tristars and a proportion of Boeing 747 airliners.
Microprocessor Based Controller for Complex Turbine Systems
Authors: Trombley James , Mathias Walter M. , Curtis Craig
Published: April 2015

The increasing complexity of control system requirements has led to the use of microprocessor based controllers on gas turbine systems. For this automotive turbine system, precise temperature controlled accelerations and modulating clutch spools demanded complex schedules and tight control of system non-linear behavior. The control system also monitors turbine performance and START/STOP requirements.

The control system hardware consists of a single string controller, fitted with auxiliary overspeed and temperature monitors. Eight proportional integral derivative (P ID) loops are run concurrently to control the fuel and clutch valves, as well as the schedules, logic and monitoring functions. The control functions are scheduled to run every 20 to 160 milliseconds, as a function of their bandwidth requirements.

System diagnostics are also provided, allowing rapid service of the system when shutdowns occur.
Penetration and Break-Up Behaviour of a Discrete Liquid Jet in a Cross Flowing Airstream: A Further Study
Authors: Hussein G. A. , Jasuja A. K. , Fletcher R. S.
Published: April 2015

Penetration and break-up characteristics of a discrete liquid jet injected into a high velocity cross flowing airstream were examined as a basis of plain-jet airblast atomizer design. The first results of this program, detailed in (4), covered the effects of liquid jet/airstream velocities and the injection orifice diameter. The results presented here cover the effects of liquid viscosity (0.001 to 0.125 Ns/m2), liquid surface tension (0.027 to 0.074 N/m), liquid density (812 to 1830 Kg/m3), the liquid jet injection angle (30 to 90 degrees) and the orifice length-to-diameter ratio (5 to 14). These tests were carried out under normal atmospheric pressure and temperature conditions using still photography for penetration profile and a laser light scattering technique for mean dropsize determination. The experimental penetration data is shown to agree reasonably accurately, with the simple model developed before (see (4)). The analysis of the experimental mean dropsize data collected in this study leads to the development of the following correlation

SMD = 1.206 σ ℓ V a 2 0.6 d j o 0.4 + 0.072 μ ℓ 2 σ ℓ ρ ℓ 0.45 d j o 0.55
Aerodynamic Tests on Centrifugal Process Compressors: Influence of Diffusor Diameter Ratio, Axial Stage Pitch and Impeller Cut-Back
Authors: Lindner Peter
Published: April 2015

Almost all process compressors manufactured today are built in accordance with the fixed geometry modular system.

It is not always possible to accurately predict the operational behaviour of a compressor particularly in such cases where a deviation from the standard solution is advisable or even necessary.

This paper describes and analyses by means of experimental measurements the influence of three different stage modifications (axial stage pitch, shortening of the vaneless annular diffusor, blading cut-back).

The results given here are directly related to engineering practice as they enable the design engineer to apply realistic efficiencies even for modified stages in the early planning stage.
Comparison of Alternative Cogeneration Power Systems for Three Industrial Sites
Authors: Harper Allen D.
Published: April 2015

Three alternative on-site cogeneration power systems were evaluated against technical and economic criteria for three industrial sites. Technical factors included plant sizing to meet process thermal loads, fuel utilization, power output, siting consideration, fuel savings, etc. Economic factors included capital cost, return on equity, and ownership/financing options among others. Each cogeneration plant was evaluated by comparison with the current separate generation scheme.

The technologies considered were 1) conventional coal-fired, steam topping cycles; 2) coal-fired, atmospheric fluidized bed/closed-cycle gas turbines; and 3) coal-fired, atmospheric fluidized bed/open cycle gas turbines. These approaches were optimized for three sites 1) an agricultural chemical plant, 2) a brewery, and 3) a kraft paper mill.

The results showed that the closed cycle gas turbines yielded the best economics, primarily due to a lower initial cost. The open cycle gas turbine, when combined with a steam bottoming cycle, resulted in larger power outputs than would be realized in the closed cycle or steam turbine cases. None of the plants studied matched the plant electrical load while following the thermal load.
The Effect of Fluid Inertia in Squeeze Film Damper Bearings: A Heuristic and Physical Description
Authors: Tichy John A.
Published: April 2015

Fluid inertia forces are comparable to viscous forces in squeeze film dampers in the range of many practical applications. This statement appears to contradict the commonly held view in hydrodynamic lubrication that inertia effects are small. Upon closer inspection, the latter is true for predominantly sliding (rather than squeezing) flow bearings.

The basic equations of hydrodynamic lubrication flow are developed, including the inertia terms. The appropriate orders of magnitude of the viscous and inertia terms are evaluated and compared, for journal bearings and for squeeze film dampers. Exact equations for various limiting cases are presented: low eccentricity, high and low Reynolds number. The asymptotic behavior is surprisingly similar in all cases. Due to inertia, the damper force may shift 90° forward from its purely viscous location. Inertia forces are evaluated for typical damper conditions.

The effect of turbulence in squeeze film dampers is also discussed. On physical grounds it is argued that the transition occurs at much higher Reynolds numbers than the usual lubrication turbulence models predict.
The TF40B, a 4000 HP Class Marine Gas Turbine for the U.S. Navy LCAC
Authors: Silver S. , Lauriat T. B.
Published: April 2015

This paper will describe the application features of the Avco Lycoming TF40B Marine Gas Turbine in the U.S. Navy Landing Craft Air Cushion (LCAC) built by Bell Aerospace, New Orleans, U.S.A.

In addition to LCAC installation items such as mounting, control, instrumentation, inlet and exhaust, a description of the engine itself will be included delineating those items peculiar to the LCAC Application and those items reflecting improvements over the TF40 engines previously used.
Gas Turbine Power Systems for Military Tracked Vehicles
Authors: Woodhouse Geoffrey D.
Published: April 2015

The gas turbine engine has been examined as a power plant for military tracked vehicles for over 30 years. Advocates have stressed the potentially high power density and high reliability as factors in favor of the turbine. Several turbine engines have been evaluated experimentally in military tracked vehicles resulting in a better understanding of such aspects as response characteristics and air inlet filtration requirements. Moreover, although the small volume and light weight of aircraft derivative gas turbines have certain virtues, it generally has been concluded that some form of waste heat recuperation is essential to achieve an acceptable level of fuel consumption, despite the increased weight and volume incurred. The selection of the AVCO Lycoming AGT1500 recuperated gas turbine as the power unit for the U.S. Army new M1 “Abrams” main battle tank was a major milestone in the evolution of gas turbine engines for tank propulsion.
Status Report: DARPA/NASA Convertible Turbofan/Turboshaft Engine Program
Authors: Bellin A. I. , Brooks A.
Published: April 2015

NASA-Lewis Research Center and the Defense Advanced Research Projects Agency are jointly funding a program to demonstrate the characteristics of a convertible turbofan-turboshaft engine. Such an engine would be capable of powering a high speed rotorcraft in vertical flight and in horizontal flight up to approximately .85 Mach number. The engine used in this program is a modification of the TF34-GE-400 engine. Testing of the convertible TF34 engine will be carried out at the Lewis Research Center, proceeded by a factory checkout at the Contractor’s facility in Lynn, Massachusetts. This paper provides a report of status to-date in the program which was initiated on May 13, 1981 and is to proceed for 39 months to August, 1984. Engine checkout at Lynn occurred in February of 1983 with testing at Lewis Research Center scheduled to begin on May, 1983.
Aircraft Turbofan Noise
Authors: Groeneweg John F. , Rice Edward J.
Published: April 2015

Recent advances in the understanding of turbofan noise generation and suppression in aircraft engines are reviewed with particular emphasis on NASA research. The review addresses each link in the chain of physical processes which connect unsteady flow interactions with fan blades to far field noise. Mechanism identification and description, duct propagation, radiation and acoustic suppression are discussed. Recent advances in the experimental technique of fan inflow control assure that in-flight generation mechanisms are not marked by extraneous sources in static tests. Rotor blade surface pressure and wake velocity measurements aid the determination of the types and strengths of the generation mechanisms. Approaches to predicting or measuring acoustic mode content, optimizing treatment impedance to maximize attenuation, translating impedance into porous wall structure and interpreting far field directivity patterns are illustrated by comparisons of analytical and experimental results. A persistent theme of the review is the interdependence of source and acoustic treatment design to minimize far field noise. Areas requiring further research are discussed and the relevance of aircraft turbofan results to quieting other turbomachinery installations is addressed.
A Comparison of Navy and Contractor Gas Turbine Acquisition Cost
Authors: Finizie L. T.
Published: April 2015

The increasing cost of weapons provided the stimulus needed for the Navy and Air Force jointly to study common engine requirements for the 1990s. Since engines require several years longer to develop than airframes, the Government sponsored the Advanced Technology Engine Study (ATES) to develop a long range propulsion plan for new aircraft needed through 2010. Because of the interaction between aircraft and engine in the design of the weapon system, aircraft engine companies teamed with aircraft companies to provide aircraft and engine conceptual designs to perform the expected missions for the 1990 time period. Life Cycle Cost (LCC) was used as the criterion in evaluating the merit of a number of USN and USAF aircraft systems.

Since operating and support costs (0&S) are the most difficult of LCC to predict accurately, this paper compares only development and production costs provided by the participating contractors with those costs determined using cost criteria developed by the Navy.
Design Considerations for Nuclear Reactor Gas Turbine Space Power Systems
Authors: Parker G. H. , Pierce B. L.
Published: April 2015

This paper reviews some of the major design trade-offs for nuclear space power based on gas cooled reactors and closed cycle gas turbines. A system rated at 100 kW(e) is considered and trade-offs involving the effects of key variables such as recuperation, pressure ratio and compressor inlet temperatures on overall system weight are presented.
Effect of Grinding Variables on Strength of Hot Pressed Silicon Nitride
Authors: Allor R. L. , Baker R. R.
Published: April 2015

An experimental study was conducted to evaluate the effect of several grinding variables on the room temperature strength of Norton NC-132 hot pressed silicon nitride. The grinding variables studied included diamond grit size, diamond concentration, type of diamond bond, downfeed rate and type of cut. Significant effects on strength were noted for all variables except diamond concentration.
Three Dimensional Inviscid Computation of an Impeller Flow
Authors: Prince T. C. , Bryans A. C.
Published: April 2015

The flow in a centrifugal impeller is analyzed by a quasi-three-dimensional streamline curvature method, by a three-dimensional Euler code, and by a three-dimensional finite element potential flow method. Comparison with Eckardt’s published data for a backswept impeller shows that full three-dimensional methods better predict the loading at the hub and shroud.
A Study of the Surface Deterioration due to Erosion
Authors: Tabakoff W. , Balan C.
Published: April 2015

Turbomachines are subject to excessive rate of erosion when operated in dusty environments or exposed to combustion gases of newly developed synthetic fuels or heavy oils. The surface quality of the blades exposed to such particulate flow deteriorates. With time, the surface roughness increases and leads to a decrease in engine performance. This paper presents the results of the experiments carried out in an erosion wind tunnel on 6061T6 aluminum specimens to study the roughness formations. The particles used were silica sand.
Measurements of the Flow From a High Speed Compressor Rotor Using a Dual Probe Digital Sampling (DPDS) Technique
Authors: Shreeve R. P. , Neuhoff F.
Published: April 2015

The flow from a high speed rotor in a rotor-first arrangement has been measured using a “dual-probe, digital sampling (DPDS)” technique. The flow field was found to be steady in rotor coordinates (periodic in machine coordinates) outside the rotor wake, and 3 components of velocity and the pressure field were determined in this area. The wake regions were unsteady. In these regions the measurements based on ensemble averages of multiple samples did not follow the behavior established during calibration in steady uniform freejet flow except near the wake center. The broadening of the wake and three dimensional effects in the flow field were measured at reduced throttle and increased speeds. The results serve to illustrate the potential of the measurement technique, on which the emphasis of the presentation is placed.
An Investigation Into the Effect of Coolant Flow on the Vibration Characteristics of Hollow Blades Conveying Fluid
Authors: Abuid B. A. , Al-Jumaily A. M.
Published: April 2015

This paper treats the free vibration of hollow symmetrical turbo-machinery blades conveying cooling fluid. The blade motion is described by using a simplified shell theory, whereas the fluid forces are described by the linearized potential flow theory. Natural frequencies are presented for the axial and circumferential modes and the effect of flow velocity and other parameters are discussed. Two models are constructed and tested with air and water as the flowing fluid. Also a beam approximation is used to justify the results at least in a qualitative manner. Experimental data and theoretical results are in good agreement and they all show that the fluid flow tends to decrease the free vibration-natural frequencies.
A Preliminary Study of Annular Diffusers With Constant Diameter Outer Walls (Suitable for Turbine Exits)
Authors: Adkins R. C. , Jacobsen O. H. , Chevalier P.
Published: April 2015

A systemmatic series of tests has been conducted on a family of annular diffusers where the outer casing is maintained at constant diameter. Such a diffuser is typical of turbine exits. Data, in the form of static pressure recovery coefficient is plotted against diffuser length for several different designs of centerbody closure.

It has been shown that such diffusers can have short length centerbodies for which a set of design guides has been established.
Design Flexibility Permits a 35000 HP Industrial Gas Turbine to Meet a Wide Range of Application Requirements
Authors: Kuly P. W.
Published: April 2015

Two recent applications for a heavy duty industrial gas turbine engine are discussed. The principal design requirements for both cases are compared and the design changes necessary to meet the requirements are illustrated. In the case of a main pipeline compressor driver, the need for high thermal efficiency over a wide range of loads is met by use of a regenerative cycle and by reprogramming the loading sequence. Long term step increases in engine capability were provided by incorporating a unique engine convertability feature.

In the case of a process air compressor driver with exhaust heat recovery, the engine exhaust temperature and gas flow imposed constraints on engine capability during high ambient temperature operation and on engine operation at low ambient temperature conditions. The constraints were met by the use of steam injection to augment power at high ambient temperature conditions and by the use of variable inlet guide vanes to control exhaust flow at the low temperatures.
Strain Isolated Ceramic Coatings
Authors: Tolokan R. P. , Brady J. B. , Jarrabet G. P.
Published: April 2015

The durability of thermally shocked high tempererature ceramic coatings on metal substrates can be dramatically improved using a fiber metal strain isolator between ceramic and metal. The fiber metal strain isolator is a compliant, porous and low modulus material which yields to control the stress on the ceramic coating during thermal cycling. Plasma sprayed strain isolated ceramic coatings .060” (1.5 mm) thick have shown excellent durability in thermal shock testing. The strain isolated ceramic coating is an excellent thermal barrier since both the ceramic and fiber metal are good insulators. Applications include ceramic thermal barrier coatings for gas turbine engine seals and turbine components, combustors, MHD electrodes, and internal combustion engine insulation.
Negative Incidence Flow Over a Turbine Rotor Blade
Authors: Joslyn H. David , Dring Robert P.
Published: April 2015

The operation of variable cycle gas turbines at negative incidence can result in highly three dimensional separated flows on the turbine rotor pressure surface. These flows can impact both performance and durability. The present program was conducted to experimentally study the behavior of surface flow on a large scale axial flow turbine rotor with incidence varying up to and including negative incidence separation. Fullspan pressure distributions and surface flow visualization were acquired over a range of incidence. The data indicate that at large negative incidence, pressure surface separation occurred and extended to 60 percent chord at midspan. These separated flows were simulated at midspan by applying potential flow theory to match the measured pressure distributions.
Gas Turbine Compressor Interstage Cooling Using Methanol
Authors: Fortin J. A. C. , Bardon M. F.
Published: April 2015

An earlier study demonstrated the theoretical potential of the concept of injecting methanol into a gas turbine compressor inlet as a means of increasing cycle thermal efficiency. To attain the full potential of such a system, continuous shifting vapour/liquid equilibrium is required which would pose formidable difficulties in practice due to the presence of liquid in the compressor blading. This study evaluates a more practicable configuration in which the alcohol is injected between stages of a multi-stage machine so that, due to the higher air temperatures, evaporation is complete before the mixture enters subsequent stages. Through a computer analysis, it is shown that this arrangement would retain most of the potential of the concept while greatly reducing the design and operating problems.
F-14 Aircraft and Propulsion Control Integration Evaluation
Authors: Davies W. J. , Hoelzer C. A. , Vizzini R. W.
Published: April 2015

Since 1976, the U.S. Navy in conjunction with Pratt and Whitney Aircraft (PWA) has been actively engaged in developing the technology base for on engine, dual redundant, fault tolerant, full authority digital electronic control (FADEC) systems with the capability of aircraft control integration for application to the next generation Navy aircraft.

Navy contracts were awarded in 1981 to PWA and Grumman Aerospace Corporation (GAC) to identify the operational benefits of the F-14 Aircraft with a dual-redundant FADEC interfaced to an Advanced Fuel Management System (AFM) and integrated with the F-14 aircraft control system. This paper presents the FADEC/F-14 integration evaluation performed by PWA and discusses the benefits of the FADEC/F-14 integrated system. These include improvements in reliability, mission abort, survivability, maintainability, cruise fuel consumption, engine weight, diagnostics and fault recording, inlet and engine air flow matching and propulsion control accuracy.
Turbomachinery Maintenance Planning
Authors: Chandler A. L. , Chapman T.
Published: April 2015

This paper presents important information for developing a comprehensive maintenance program for turbomachinery. It describes the primary factors affecting the planning process, and focuses on the responsibilities and interface between the manufacturer and user. It also provides an overview of the latest maintenance techniques vital to a successful turbomachinery maintenance program.
The Coal-Fired Gas Turbine Locomotive: A New Look
Authors: Liddle S. G. , Bonzo B. B. , Purohit G. P.
Published: April 2015

The idea of a coal-fired gas turbine locomotive dates back over a half century with significant developments being made in the decade between 1944 and 1955. These developments did not lead to a locomotive which could compete with the Diesel locomotive. Today, with the increase in the price of Diesel fuel, a new look at coal-fired gas turbines is appropriate. Advances in turbomachinery technology and new means of coal combustion may have made it possible to develop a competitive locomotive. Of the various combinations of combustors, cycles, and turbines, the external combustion, closed cycle regenerative gas turbine with a fluidized bed coal combustor appears to be the best suited to this application. The external combustion, open cycle regenerative gas turbine; and the internal combustion, open cycle regenerative gas turbine with a coal gasifier are the second and third choices.
Squeeze-Film Damper Technology: Part 1 — Prediction of Finite Length Damper Performance
Authors: Lund J. W. , Smalley A. J. , Tecza J. A. , Walton J. F.
Published: April 2015

Squeeze-film dampers are commonly used in gas turbine engines and have been applied successfully in a great many new designs, and also as retrofits to older engines. Of the mechanical components in gas turbines, squeeze-film dampers are the least understood. Their behavior is nonlinear and strongly coupled to the dynamics of the rotor systems on which they are installed. The design of these dampers is still largely empirical, although they have been the subject of a large number of past investigations.

To describe recent analytical and experimental work in squeeze-film damper technology, two papers are planned. This abstract outlines the first paper, Part 1, which concerns itself with squeeze-film damper analysis. This paper will describe an analysis method and boundary conditions which have been developed recently for modelling dampers, and in particular, will cover the treatment of finite length, feed and drain holes and fluid inertia effects, the latter having been shown recently to be of great importance in predicting rotor system behavior. A computer program that solves the Reynolds equation for the above conditions will be described and sample calculation results presented.
Development Status of Coal-Fired Gas Heaters for Brayton-Cycle Cogeneration Systems
Authors: Gunn S. V. , McCarthy J. R.
Published: April 2015

Under contract from the Department of Energy, Rocketdyne is developing the technology of coal-fired gas heaters for utilization in Brayton-cycle cogeneration systems. The program encompasses both atmospheric fluidized bed and pulverized coal combustion systems; and it is directed toward the development of gas heater systems capable of delivering high pressure air or helium at 1550 F, when employing metallic heat exchangers, and 1750 F, when employing ceramic heat exchangers. This paper reports on the development status of the program, with discussions of the completed “screening” corrosion/erosion tests of candidate heat exchanger materials, a description and summary of the operating experience with the 6- by 6-foot AFB test facility and a projection of the potential for relatively near term commercialization of such heater systems.
Experience With the Development of an Euler Code for Rotor Rows
Authors: Nenni J. P. , Rae W. J.
Published: April 2015

An Euler code for the transonic flow through an axial flow rotor has been developed. The method of solution is an implicit time marching scheme and approximate factorization has been used to minimize the computations. Although the basic methods have been well publicized in the external aerodynamics literature, several modifications were found to be crucial in order to apply the methods to internal flows. the internal flow calculations appear to be much more susceptible to instabilities than the external flow calculations. A boundary-fitted coordinate system is used which is an adaptation of one due to Ives. The calculation of the metrics of the transformation proves to be extremely important and a revision of the numerical viscosity treatment enlarges and enhances the domain where converged solutions can be obtained. In particular, it was found that the metrics must be discretized in the same spatial fashion as the governing partial differential equation in order to avoid introducing source-like terms which would quickly destroy the solution. Results are presented for the two-dimensional case of flows through a cascade with inlet Mach numbers up to 0.76 and with outlet conditions prescribed and with a Kutta condition applied.
A Configuration to Improve the Aerodynamics and Scope of Can-Annular Combustors
Authors: Adkins R. C. , Binks D.
Published: April 2015

Aerodynamic tests on a novel concept of pre-combustor diffuser, particularly suited to can-annular configurations, are described. These tests show that the new arrangement avoids the unstable flow separations and some of the parasitic pressure losses which can be experienced in more conventional arrangements.

With the benefit of improved flow conditions, it is argued that the can-annular combustor arrangement has many advantages over other configurations, particularly for large engines, and where exhaust gas pollutants must be kept to a minimum.
Inlet-Fan Flow Field Computation
Authors: Matwey Mark D. , Seidel Barry S. , Farrell Charles A.
Published: April 2015

The flow field of a tilt-nacelle inlet-fan combination used for V/STOL aircraft is studied. Under certain flight conditions the inlet is subjected to high angles of attack and/or yaw. This produces a non-uniform or distorted flow field at the fan-face that can lead to large blade stresses. This paper presents an analytical approach to the coupled inlet-fan problem. The nacelle is modelled by a distribution of source panels and the fan by a distribution of radial vortices. A modified actuator disc with losses and a quasi-steady rotor response is used to derive the boundary condition at the fan-face. An example of the calculation is shown.
Temperature Traverse Quality in the Gas Turbine Combustor Using Heavy Fuels
Authors: Najjar Yousef S. H.
Published: April 2015

One of the most important performance requirements and most difficult to achieve is a uniform distribution of temperature in the exhaust gases of the gas turbine combustor. This is expected to be impaired by the trend of using heavier fuel oils. Measurements in a developed experimental combustor at various air pressures, inlet temperatures, air fuel ratios and fuel blends showed the importance of these operating parameters in optimizing the combustor design.
The Purpose, the Principles and the Problems of Fault Tolerant Systems
Authors: Eccles E. S.
Published: April 2015

This paper sets out to present a non-specialist overview of what fault tolerant systems are intended to achieve, the various possible approaches (from simple to complex) which are followed, how well they meet the goals and the particular problems or advantages they possess. The source data for the paper and its background is aviation gas turbine controls but the principles are of general application.

Fault tolerance is aimed at obtaining greater system availability without compromising safety. Many different system configurations have been postulated or tried out. The paper considers 11 and deals in detail with several of them, covering a wide range of cost and complexity. The choice between these diverse systems depends upon application, installation, the powerplant/vehcile configuration and most importantly on the complexity of the control hardware. It involves choices of actuation system, monitoring methods, failure recovery and, in digital systems, software. The paper explains the rationale and the significance of each influence.

Each configuration can be applied more or less successfully to a range of control uses. The discussion indicates which special features are advantageous and which are disadvantageous in different regions of the applications spectrum.

Relative representative cost and reliability figures are given for each configuration and, for aviation types of design, relative sizes and weights.

There is no single, generally applicable “fault tolerant system”. The issues are basically simple but frequently confused. It is the aim of the paper to clearly present these issues and the merits of various configurations in general terms and to promote wider and better informed discussion of them.
On the Influence of the Diffuser Inlet Shape on the Performance of a Centrifugal Compressor Stage
Authors: Bammert K. , Jansen M. , Rautenberg M.
Published: April 2015

Results from an experimental study of the influence of the diffuser inlet shape on the performance of the diffuser and the whole compressor stage are presented. The investigations were carried out using a single stage centrifugal compressor. Three different vaned diffusers were tested. From detailed flow field measurements the influence of the diffuser inlet shape on the performance of the essential components of the compressor stage, i.e. the impeller, the diffuser, and the collecting chamber was analyzed. It is shown that the reaction of the vaned diffuser on the efficiency of the impeller is only weak but the losses in the collecting chamber are considerably affected by the used diffuser types.
Flashback in Prevaporizing/Premixing Combustion Systems
Authors: Nein A. G. , Mellor A. M.
Published: April 2015

Upstream flame propagation in prevaporizing/premixing continuous combustors was examined. Simplified axisymmetric burners used in this investigation were selected to simulate the same fundamental combustion processes in practical hardware. Straight cylindrical premixing tubes were used to reduce the possibility of upstream flame propagation mechanisms not associated with classical flashback. Combustor pressure oscillations were monitored and indicated that no flashback occurred due to these oscillations. Propane was selected as the test fuel because of its rapid vaporization characteristics.

A characteristic time approach was used to analyze the data because the flashback process can be viewed as a competition between a fluid mechanic time and a chemical reaction time. Use of this technique revealed that stoichiometric contours existed in the premixing tubes of this system at most overall equivalence ratios tested, since the flashback limit was observed to be independent of overall stoichiometry.
On the formation of copper nanoparticles in nanocluster aggregation source
Authors: Dutka Mikhail V. , Turkin Anatoliy A. , Vainchtein David I. , De Hosson Jeff Th. M.
Published: April 2015

The influence of pressure and type of inert gas (Ar and Kr) on the morphology and size distribution of nanoparticles produced in a nanocluster source is studied experimentally. The experimental data are used to validate the model of cluster formation from a supersaturated atomic vapor in an inert buffer gas, which has been developed in our previous paper. The model predictions are in accordance with the experimental findings.
Laboratory- and Field-Based Assessment of Maximal Aerobic Power of Elite Stand-Up Paddle-Board Athletes
Authors: Schram Ben , Hing Wayne , Climstein Mike
Published: April 2015

Purpose:

Stand-up paddle boarding (SUP) is a rapidly growing sport and recreational activity for which only anecdotal evidence exists on its proposed health, fitness, and injury-rehabilitation benefits. Participants: 10 internationally and nationally ranked elite SUP athletes.

Methods:

Participants were assessed for their maximal aerobic power on an ergometer in a laboratory and compared with other water-based athletes. Field-based assessments were subsequently performed using a portable gas-analysis system, and a correlation between the 2 measures was performed.

Results:

Maximal aerobic power (relative) was significantly higher (P = .037) when measured in the field with a portable gas-analysis system (45.48 ± 6.96 mL · kg−1 · min−1) than with laboratory-based metabolic-cart measurements (43.20 ± 6.67 mL · kg−1 · min−1). There was a strong, positive correlation (r = .907) between laboratory and field maximal aerobic power results. Significantly higher (P = .000) measures of SUP paddling speed were found in the field than with the laboratory ergometer (+42.39%). There were no significant differences in maximal heart rate between the laboratory and field settings (P = .576).

Conclusion:

The results demonstrate the maximal aerobic power representative of internationally and nationally ranked SUP athletes and show that SUP athletes can be assessed for maximal aerobic power in the laboratory with high correlation to field-based measures. The field-based portable gas-analysis unit has a tendency to consistently measure higher oxygen consumption. Elite SUP athletes display aerobic power outputs similar to those of other upper-limb-dominant elite water-based athletes (surfing, dragon-boat racing, and canoeing).
An analysis of critical factors for quantitative immunoblotting
Authors: Janes Kevin A.
Published: April 2015

Sample preparation, detection scheme, and normalization approach affect the quantification of protein abundance and modification state by immunoblotting.
Focus Issue: Tackling reproducibility and accuracy in cell signaling experiments
Authors: Gough Nancy R.
Published: April 2015

Science Signaling
highlights common sources of error in experimental design and in interpreting biological data.
Natural-born killers for tumors
Authors: Mueller Kristen L.
Published: April 2015

Soluble proteins shed by tumors stimulate natural killer cell–mediated antitumor immunity in mice.