bluuebunny/crossref_metadata_2025 huggingface dataset:
Lubricated Extrusion of “T” Sections from Aluminum, Titanium and Steel Using Computer-Aided Techniques
Authors: Nagpal V. , Billhardt C. F. , Altan T.
Published: November 2010

This paper describes the application of computer-aided techniques to the lubricated extrusion of shapes such as L’s and T’s. A simple analysis of the lubricated direct-extrusion process is developed and used to formulate a design procedure for determining the optimum shape of the extrusion dies. To manufacture these complex dies by NC (Numerical Control) machining and EDM (Electro-Discharge Machining), special computer programs are written. The die design and die manufacturing computer programs are integrated into an interactive computer software package called “SHAPE”. To evaluate “SHAPE”, a streamlined die for extruding “T” sections was designed and manufactured with this computer system. Billets of titanium alloy Ti-6Al-4V, AISI 4340 steel and aluminum 7075 were extruded through this streamlined die using suitable lubrication systems. Results of these trials show the usefulness and the validity of the developed computer-aided techniques.
Hyperhemispherical Viewports for Undersea Applications
Authors: Stachiw J. D.
Published: November 2010

Hyperhemispherical windows with included spherical angles in the 260–270 degree range have been fabricated from acrylic plastic and glass for a variety of undersea applications. When seated in NOSC rigid metallic mountings with conical seats they withstood cyclic design working pressures without failure, or cracking providing that a thin elastomeric gasket was interposed between the mating conical bearing surfaces, and two elastomeric O-rings served as compliant bushings between the spherical surfaces of the window and the retaining surfaces of the mounting. Tests have shown that (1) critical pressures of acrylic plastic hyperhemispheres can be predicted with acceptable accuracy by analytical and empirical relationships developed previously for acrylic plastic hemispheres and spheres, (2) the mounting retains and seals plastic or glass windows in −40 to 120° F ambient temperature range even when subjected to lateral dynamic loading of 17G magnitude, and (3) dimensionally identical hyperhemispheres fabricated from glass and seated in the same mounting do not fail under a single pressurization at twice the critical pressure of acrylic windows.
Empirical Equations for Describing the Strain-Hardening Characteristics of Metals Subjected to Moderate Strains
Authors: Adams C. , Beese J. G.
Published: November 2010

The strain-hardening characteristics of a metal have often been described by a power function which employs a work-hardening exponent, “n.” Usually the material is assumed to be rigid to the yield point and therefore the possibility of any elastic recovery is denied. The authors show that, particularly for the initial portion of a stress-strain curve, n is not a constant and therefore the curve cannot be described by one power law alone. A method is proposed for fitting equations to experimental stress-strain curves up to strain values of 0.05. The equations take into account possible elastic recovery. The equations should facilitate more accurate assessment of underload stress and strain distributions in various design problems.
Predicting the Fracture Initiation Transition Temperature in High Toughness, Low Transition Temperature Line Pipe With the COD Test
Authors: Podlasek R. J. , Eiber R. J.
Published: November 2010

This paper describes the use of the crack opening displacement (COD) test to predict the fracture initiation transition temperature of high toughness, low-transition temperature in line pipe. A series of COD tests using t × t and t × 2t specimens made from this line pipe material. The COD test was conducted over a range of temperatures and the point where the upper shelf COD values began to decrease with decreasing temperature was defined. To verify the full-scale significance of this temperature, a series of three experiments was conducted on 48-in. (1.22m) dia line pipe to bracket the transition temperature defined in the COD Test. The results suggest that the COD transition temperature can ve used to define the fracture initiation temperature for static loading in pipe. In addition, in the transition temperature region, the full-scale results, while limited in number, suggest that the COD values could possibly be used to predict the critical flaw sizes in the pipe material.
Effect of Friction and Specimen Geometry on the Ductile Fracture in Upset Forging
Authors: Samanta S. K.
Published: November 2010

Experiments were conducted to determine the effect of interface friction and specimen geometry on the useful ductile flow limit of 1100 aluminum and 1095 steel at room temperature. The tests consisted of measuring the equatorial strains during simple upsetting of circular cylinders. From the measured strains the surface stress components were calculated. All occurrences of fracture were observed to be the normal type. In some cases no surface cracks were observed and a possible explanation is given in the paper.
The Mechanical Behavior of Rapidly Solidified Al-Al2Cu and Al-Al3Ni Eutectics at Elevated Temperatures
Authors: Bright M. W. A. , Taplin D. M. R. , Kerr H. W.
Published: November 2010

The mechanical behavior of semi-continuously cast Al-Al2Cu and Al-Al3Ni eutectics has been studied in tension at temperatures between 350–500 deg C (Al-Al2Cu) and 500–625 deg C (Al-Al3Ni). The microstructures of both eutectics were found to be relatively unstable at elevated temperatures, even in the absence of deformation, as a result of their fine, imperfect microstructures in the as-cast condition. During deformation spheroidization occurred rapidly, so that the fibrous/lamellar reinforcement was largely eliminated. During hot deformation of the Al-Al2Cu eutectic, the “degenerate” lamellar structure was gradually replaced by an equiaxed microduplex structure via polygonization of both phases. This structure subsequently demonstrated superplastic flow, with an increase in the strain-rate sensitivity index from about 0.3 to about 0.5. Final failure resulted from nucleation of cavities at Al2Cu - Al2Cu - Al triple junctions with cavity growth along Al2Cu-Al2Cu grain boundaries. The Al-Al3Ni eutectic did not exhibit superplastic flow probably due to the lower volume fraction of the Al3Ni phase, which “spheroidized” during deformation. A process for fabricating wire by a continuous process from the melt is outlined.
Differential Testing and the Evaluation of Thermal Activation
Parameters
Authors: Wagner J. G.
Published: November 2010

Thermally activated mechanisms of dislocation motion and interaction account for the dependence of stress on strain, temperature, and time during plastic deformation. Much of the recent activity in identifying particular mechanisms has involved the use of differential type thermomechanical tests. Due to certain basic and recurrent oversights in applying thermal activation theory to such test data, the results are oftentimes misleading. These limitations are identified and explored. Minimum requirements for an accurate characterization of strain history effects are established. A limited amount of self-contained isothermal data, for aluminum and lead, have been obtained in the intermediate strain-rate range which critically test the hypotheses. The present results indicate that the results reported by others may be in substantial error. Much of the discussion presented also applies, in its most basic form, to the evaluation of constitutive models which are not microstructurally based.
Fatigue-Crack Growth in an X-65 Line-Pipe Steel at Low Cyclic Frequencies in Aqueous Environments
Authors: Vosikovsky O.
Published: November 2010

The effects of salt and distilled water environments on fatigue-crack growth rates have been evaluated for an X-65 line-pipe steel. Tests were conducted over a frequency range between 10 and 0.01 Hz, under conditions of cathodic potential and free corrosion. A distinct pattern in the functional dependence of growth rates on ΔK and frequency has been found. Maximum environmental enhancement of growth rates was 50 times that of air at a cathodic potential of −1.04V, and 10 times that of air at a free-corrosion potential of −0.68V. In each case it occurred at the lowest frequency and at relatively high values of ΔK. Hydrogen embrittlement and the two-stage cracking process are examined as the main mechanisms of growth acceleration.
A Constitutive Equation for High Temperature Flow
Authors: Paton N.
Published: November 2010

A constitutive equation which describes the behavior of strain rate sensitive materials which do not strain harden significantly is often required in the solution of various problems involving metal flow. Such an equation, containing four adjustable but physically meaningful constants, is proposed, and is based on equation suggested by Ashby and Verrall. The equation is shown to describe the deformation of a titanium alloy at high temperature with good accuracy.
Phenomenological Analysis of Plastic Spherical Indentation
Authors: Francis H. A.
Published: November 2010

Functional relationships describing the “expected” deformation behavior of a spherically indented surface are obtained by statistical analysis of published data. The representative strain εR of the indentation, the ratio ψ of mean contact pressure to representative flow stress YR(εR), the shape of the interfacial pressure distribution p(r), the plastic boundary dimensions, and the displacement at the contact circumference can each be expressed, with specified precision, as functions of the altitude to base radius ratio h/b of the displaced spherical segment, the flow stress to Young’s modulus ratio YR/E (a measure of elastic strain capacity), and the Meyer index m (a measure of strain-hardening rate). Only εR and ψ are independent of m. Whereas εR = 0.43h/b, all other variables are predicted more precisely by φ = (h/b)/(YR/E) than by h/b. After plastic flow commences (φ = 1.15), ψ = 1.1 + 0.53 lnφ until φ = 27, beyond which ψ = 2.87. The extent of plastic flow during unloading can be predicted from p(r), which becomes flatter as φ and/or m increase.
High Strain Rate Tensile Properties of Annealed 2 1/4 Cr-1 Mo Steel
Authors: Klueh R. L. , Oakes R. E.
Published: November 2010

The high strain rate tensile properties of annealed 2 1/4 Cr-1 Mo steel were determined and the tensile behavior from 25 to 566°C and strain rates of 2.67 × 10−6 to 144/s were described. Above 0.1/s at 25°C, both the yield stress and the ultimate tensile strength increased rapidly with increasing strain rate. As the temperature was increased, a dynamic strain aging peak appeared in the ultimate tensile strength-temperature curves. The peak height was a maximum at about 350°C and 2.67 × 10−6/s. With increasing strain rate, a peak of decreased height occurred at progressively higher temperatures. The major effect of strain rate on ductility occurred at elevated temperatures, where a decrease in strain rate caused an increase in total elongation and reduction in area.
Fatigue of Metals as Stochastic Phenomena
Authors: Ihara C. , Tsurui A.
Published: November 2010

A stochastic model for the fatigue of metals under repeated stress or strain is proposed. Fatigue lives up to crack initiation are investigated with the aid of a recent theory on a cumulative process and the mean values are plotted versus stress amplitudes. Of interest is the fact that this curve behaves as if the endurance limit existed when the parameters are adequately taken. Except the neighborhood of the endurance limit, the coefficients of variation are also calculated approximately.
Irradiation Effects on the Behavior of Structural Materials at Elevated Temperature
Authors: Abo-El-Ata M. M.
Published: November 2010

The paper provides a qualitative review of the effects of fast neutron irradiation on the mechanical behavior of materials used in the construction of Fast Breeder Reactor Core Components. The paper is presented in three sections. First, effects of preirradiation on the strength, ductility, elastic moduli, thermal creep, creep-rupture, and fatigue are discussed. Second, the phenomenon of irradiation induced swelling is explained and the effects of temperature, cold work, and stress on swelling are presented. Third, irradiation creep is defined and the effects of temperature, stress, and cold work on irradiation creep are discussed. The review is based on the most recently available experimental data on austenitic stainless steels.
Fracture Mechanics of Composite Materials
Authors: Dharan C. K. H.
Published: November 2010

The applicability of fracture mechanics to conventional isotropic materials has been well demonstrated. For fiber-reinforced materials, however, fracture mechanics investigations have met with mixed results. For collinear crack extension of a crack on a plane of symmetry in orthotropic materials, fracture behavior has been successfully predicted using linear elastic fracture mechanics concepts; however, extrapolation to other fiber orientation combinations has been less successful. This is because fracture in anisotropic materials is more complex than in isotropic materials and is governed by additional parameters such as fiber orientation, lamination order and the constitutive relations that describe the mechanical responses of the fiber, the matrix and the interface. This paper reviews the fundamentals of fracture mechanics for isotropic materials and discusses its extension to orthotropic materials. This is followed by a discussion of the variety of failure modes observed in composites and a review of the predominant fracture mechanics theories that attempt to predict fracture using semi-empirical parameters. The main aim of this paper is to present a survey of the field in its current state and to demonstrate the approach taken by each investigator. The paper concludes with two examples where linear elastic fracture mechanics concepts have been satisfactorily employed for composite materials.
JIc Determination Using the Proposed Standard C-Shaped Specimen
Authors: LaForce C. H. , Morrison J.
Published: November 2010

The proposed standard C-shaped Specimen for KIc determinations according to ASTM E399 is readily adaptable to load line deflection measurement, and thus to J-integral assessment, using procedures currently being developed for other geometries. Tests have been conducted on quenched and tempered steels to provide comparisons of JIc and KIc using both C-shaped and compact tension specimens. The effect of specimen thickness on the crack growth resistance curve and JIc has also been examined and analyzed in relation to the allowed thickness range for the proposed test method. The Merkle and Corten corrections for the C-shaped Specimen have been calculated and compared to those for other specimen geometries. J estimates based on total displacement measurements have been found to be acceptable even at short relative crack depths.
Contrasting Fracture Models For Granite Under Dynamic Loading
Authors: Glenn L. A. , Janach W.
Published: November 2010

A “symmetric impact” experiment was used as the basis for comparing different models of the fracture mechanism in granite. Two different tensile fracture models were considered, but better results were obtained when both shear and tensile fracture were admitted. The combined model employs a fracture criterion based on static measurements of the tensile and triaxial compressive strength and emphasizes the role of bulking, which is related directly to the local rate of energy dissipation. It is shown that the behavior subsequent to incipient fracture has a major influence on the overall material response.
Hydrogen Gas Generation in Water Heat Pipes
Authors: Pittinato G. F.
Published: November 2010

Water heat pipes were fabricated from 316, 347, and 430 stainless steel, Monel 400, CDA 715, Inconel 600, and Incoloy 800. All of these materials generated varying amounts of hydrogen gas during the first few days of operation. However, as the heat pipes continued to operate, the amount of gas in each heat pipe, excluding 430 stainless steel, decreased by permeating through the heat pipe walls. Inconel 600 appeared to be the most acceptable material for water heat pipes by returning to isothermal operation over a short time period. An equation based on a diffusion dependent mechanism was developed that predicts heat pipe performance recovery rates.
The Design and Mechanical Performance Characteristics of the Zero Power Plutonium Reactor
Authors: McCarthy P. B. , Lawroski Harry
Published: November 2010

The Zero Power Plutonium Reactor (ZPPR) is a fast experimental reactor that operates at very low power levels and is used to simulate proposed fast power plutonium reactors in the 1000-MW range. The reactor is built on two large tables, one stationary and one movable, with numerous roller bearings on the underside for ease of travel. Half of the reactor is built on each table, and then the tables are brought together before the reactor can go critical. The tables are each designed to support at least 120 tons of fuel and structural material. Load tests were conducted to prove the system and to determine deflections in the foundation and runways. Many safety devices are built into the table drive system, such as an electric feed-rail system that disconnects the power supply to the drive motor if a relay fails, three speeds of table closing to control reactivity-addition rates, and two independent table-separation systems. Fuel control rods are used for reactivity changes; fuel and poison safety rods are used for shutdown control. Core material is loaded into 2 × 2 × 23-in. drawers, and the drawers are slid into matrix tubes stacked 10 feet high on the tables. Matrix tubes and drawers and the tables were aligned to obtain a minimum gap at the interface.
A Technology for Rotary Compressors
Authors: Scheel L. F.
Published: November 2010

This article presents a method of evaluating the three losses of charging, leakage and “warm-up” involved in operating the five different types of rotary displacement compressors. A comprehensive method of determining the compression efficiency, volumetric efficiency and discharge temperature is included. The limiting tip speeds, compression ratios and sizes are presented categorically. Typical application examples are given.
Measured and Predicted Secondary Flows in a Centrifugal Impeller
Authors: Howard J. H. G. , Lennemann E.
Published: November 2010

The complete velocity distribution, including both primary and secondary velocities, has been measured in passages of centrifugal impellers of simple shape. Comparison is made with theoretically predicted secondary vorticities based on a simple combination of an inviscid primary flow and a streamwise vorticity generation analysis. The measured velocities were obtained in a water-flow impeller rig using a miniature, cylindrical, hot-film probe positioned on the rotating impeller and traversed and controlled remotely through slip rings. The understanding of the complex flow patterns was assisted by a photographic study employing a hydrogen bubble, flow visualization technique.
A Model for Flow Distribution in Manifolds
Authors: Bajura R. A.
Published: November 2010

An analytical investigation of the performance of flow distribution systems was conducted for both intake and exhaust manifolds. Primary emphasis was placed on configurations in which the lateral tubes formed sharp-edged junctions at right angles to the manifold axis. A mathematical model describing the flow behavior at a discreet branch point was formulated in terms of a momentum balance along the manifold. The model was extended to the case of continuous discharge or intake for a uniformly porous manifold. Numerical solutions of the governing flow distribution equation were obtained and compared with experimental data. Dimensionless parameters characterizing the performance of manifolds were formulated from the analytical model.
An Approximate Solution to the Shuttle Heat-Transfer Losses in a Reciprocating Machine
Authors: Rios P. A.
Published: November 2010

The axial heat transfer due to the oscillatory motion of a long displacer in a cylinder with an axial temperature gradient is treated. The effect of the resistance to heat transfer due to the radial clearance between the displacer and the cylinder is considered, as well as the effect of a limited thermal diffusivity in the walls. A method for the estimation of the effect of the gas flow in the clearance volume is presented. A simple approximate solution is obtained by linearization and application of Fourier series. The effect of radial clearance, material properties, length, and wall thickness on the net heat transfer rate is discussed.
Char Burning MHD Systems
Authors: Way S.
Published: November 2010

This paper indicates the levels of plant thermal efficiency that might be anticipated from three MHD systems (two burning char and oxygen, one burning char and air) featuring reaction of the char and CO2 leading to a CO-rich gas that would then be oxidized to give a virtually ash-free working fluid. The plants analyzed also featured recirculation of combustion products, somewhat analogously to the semiclosed gas-turbine cycle. Since the gaseous working medium might be quite free from ash constituents if this method of reacting the fuel is successful, rather high air preheat temperatures obtained in regenerative heaters might prove feasible. A further finding is that, if chemical regeneration is employed by reacting the fuel with the gases exhausting from the generator efficiencies in the 55 to 57 percent range may be realized with relatively moderate preheat temperatures.
Measured and Predicted Flow Near the Exit of a Radial-Flow Impeller
Authors: McDonald G. B. , Lennemann E. , Howard J. H. G.
Published: November 2010

Experimental measurements are presented of the velocity field near the exit of a radial impeller with backward-curved blades. The flow pattern, and its variation with changes in the flow coefficient, are compared with numerical predictions on a blade-to-blade plane. The theoretical flow prediction method assumes inviscid flow, is essentially two-dimensional and is based on the streamline curvature approach. It does not specifically require the condition of zero absolute vorticity. The comparison with experiment indicates that the principal feature of the flow not accounted for in the inviscid model is the region of low velocity near mid-blade height on the suction surface, especially for higher blade loadings.
Evaluation and Development of Engine Components and Accessories With Electrodynamic Shakers
Authors: Law R. M.
Published: November 2010

The electrodynamic shaker is a useful tool in the evaluation and development of engine components and accessories. As the shaker vibratory input to the component fixture or the engine assembly is controlled, the vibratory response of the component or accessory can be determined. A brief review of vibration theory and vibration response of several simple mechanical elements is included. Three examples of the development of engine components by use of fatigue fixtures and three examples of evaluation of engine mounted accessories are presented.
An Investigation of the Contribution of Solar Energy in Heating Greenhouses in Quebec
Authors: Lawand T. A. , Malik M. A. S. , Alward R. , Hopley P.
Published: November 2010

An experimental study on a commercial greenhouse in Montre´al, Que´bec, was undertaken during the winter season, October 1971–April 1972. The object of the study was to determine the percentage of the heat load that is provided by solar energy during the winter season. It was found that the monthly average of solar energy thermal contribution varied from 13 to 54 percent, the rest of the heating load was, of course, supplied from a conventional fuel-fired furnace. It was seen that during the coldest part of the winter in Montre´al the solar energy contributed very little toward the heating of the greenhouse and its main function was confined to that of triggering photosynthesis. It appears that there is a definite need of redesigning greenhouse structures in Que´bec such that the solar energy would play a larger role in heating them. This is necessitated because there is a need both to reduce the heating expenses and conserve fuel resources. The average cost of heating was found to be of the order of $5.00 per square meter of greenhouse.
Clean Fluid Fuels From Coal and Wastes
Authors: Forney A. J. , Haynes W. P.
Published: November 2010

The paper discusses the need for substitute supplies of the clean fuels, gas, and oil, Processes which are being developed to meet that need—coal-to-gas, coal-to-oil, wastes-to-gas, and wastes-to-oil—are listed and defined.
Inviscid Flow Through a Cascade of Thick, Cambered Airfoils: Part 1—Incompressible Flow
Authors: Frith D. A.
Published: November 2010

Conformal mapping is one means of determining the inviscid, incompressible, two-dimensional flow through a cascade of airfoils. The complex potential flow about a unit circle is a convenient picture plane. The form of mapping function required to transform this circle to thick, cambered airfoils in cascade is derived and then compared with the analogous mapping function for the isolated airfoil. Two analytical mapping functions that conform to this form are derived. One, which is in differential form and so necessitates numerical integration to yield the profile shape, has seven free parameters giving the solidity and stagger of the cascade and the camber and leading and trailing edge radii of the blading: the two remaining parameters control the thickness and camber distributions. The second analytical mapping function is in an integral form but has only five degrees of freedom corresponding to solidity, stagger, camber, leading and trailing edge radii in its basic form. Due to its simplicity, the second of these mapping functions is useful in determining basic features of the flow through cascades. These features are illustrated by some results.
Low Emissions Combustion for the Regenerative Gas Turbine: Part 2—Experimental Techniques, Results, and Assessment
Authors: Azelborn N. A. , Wade W. R. , Secord J. R. , McLean A. F.
Published: November 2010

This second part, of a two part paper, describes an experimental program to demonstrate the low emissions turbine combustor concept developed in Part 1. The paper discusses the combustor test rigs and instrumentation used as well as the experimental combustor hardware. A summary of the lean homogeneous combustion concept is presented along with a brief discussion of the requirement for variable combustor geometry. Test data are presented comparing the emissions from the experimental combustor with those from a conventional can-type combustor. These results show that, over a wide range of engine conditions, the steady-state emissions of NOx, CO, and UHC are below the numerical levels specified in the Federal standards applicable to 1976 and subsequent model year light duty vehicles. The results are related to theoretical calculations and an assessment of progress and remaining problems is made.
A Triboelectrogasdynamic Gun
Authors: Coffee R. A.
Published: November 2010

A device is described in which powder particles are pneumatically transported so as to achieve high-voltage energy conversion by contact and separation of dissimilar surfaces (triboelectricity). The device forms part of a system by means of which powders may be electrostatically sprayed. Applications are envisaged in operations ranging from metal-surface finishing to agricultural crop protection.
Corrosion and Deposits From Combustion of Solid Waste—Part III: Effects of Sulfur on Boiler Tube Metals
Authors: Krause H. H. , Vaughan D. A. , Boyd W. K.
Published: November 2010

Sulfur plays a significant part in the corrosion of heat transfer surfaces in municipal incinerators. The nature of the deposits and the extent of corrosion on simulated boiler tube surfaces has been investigated in a combined field and laboratory study. The corrosion resulting from the accumulation of deposits and the action of flue gases on boiler tube metals has been measured by probes exposed in large municipal incinerators. In addition, laboratory experiments were conducted under controlled environments to provide additional data for determination of reaction mechanisms. The amount of sulfur in the solid waste was found to be a controlling factor in the corrosion, and increasing the amount of sulfur resulted in reduced corrosion rates on boiler tube metals. This effect has important implications for the combined firing of refuse and fossil fuels.
Theoretical Research on Propeller Type Current Meters
Authors: Takeda R.
Published: November 2010

This paper reports the analytical results of the motions of current meters with low aspect ratio blades. Results obtained tell that calculation values of the lifting surface theory coincide with experimental results at apparent runaway speed of all runners. If the results of the lifting line theory are compensated, calculation results of each high pitch model nearly become equal to each experimental value. Moreover, constant pitch meters show better characters than variable pitch meters, concerning velocity fields around runner blades. From the foregoing results, the fundamental equations of the current meter runner designs are brought out.
Performance Development of the Gem Turboshaft Engine
Authors: McKenzie A. B. , Bayne B. T.
Published: November 2010

The Gem turboshaft engine designed specifically for helicopter application has provided challenges both in performance development and analytical techniques. A number of the more interesting component performance problems are discussed in this paper, together with the analysis techniques developed to meet the requirement for consistent and accurate assessment of turbine operating temperature.
Preliminary Study of Low Emission Gas Turbine Combustor With Airblast Fuel Atomizer
Authors: Yamanaka K. , Nagato K.
Published: November 2010

Recent papers describe that an airblast fuel atomizer is very effective for reducing emissions from a gas turbine and this type of fuel injector is being applied to practical engines. This paper deals with the new type of airblast fuel atomizer AFIT which comes from “Airblast Fuel Injection Tube” that makes fuel to break up into droplets by atomizing air at several small holes on the tube wall and fuel is well mixed with atomizing air instantly at the exits of holes. Regarding this AFIT, the fuel spray characteristics, combustion stability which is usually narrow for the combustor with an airblast fuel atomizer at lower engine speeds and exhaust emission levels are experimented and its effectiveness is discussed.
Experiments Concerning the Response of Supersonic Nozzles to Fluctuating Inlet Conditions
Authors: Zukoski E. E. , Auerbach J. M.
Published: November 2010

The noise field produced by the passage of pressure and entropy fluctuations through a supersonic nozzle has been investigated in an experimental program. Magnitude and phase information for the disturbances produced within the nozzle are presented and are compared with numerical calculations.
Load-Deformation Behavior of Elastic Beam-Columns on Yielding Foundations
Authors: Shahravan C. , Soler A. I.
Published: November 2010

The effect of an elastic-perfectly plastic foundation on compressive load carrying capacity of beam columns is considered. The configuration studied simulates a power plant condenser support plate acting as a column member to support the condenser walls against excessive deformation due to vacuum pressure. The yielding foundation represents the effect of the condenser tube bundle which can resist support plate bending through frictional action between the plate and the tubes. The equation governing lateral motion of the beam column is developed in rate form using the Green’s function for an elastic beam column. An approximate incremental solution is obtained enabling the load-deformation history of the beam column to be studied incorporating elastic-plastic loading and unloading of the foundation. “Failure” is assumed to occur when the maximum stress in the beam column reaches a preset allowable design value.
Considerations When Converting Industrial Plants to Coal Firing
Authors: Coles W. F. , Stewart J. T.
Published: November 2010

With fuel supplies changing and directives of policy being formulated, the use of coal for the industrial plant is of major concern for many owners. This paper discusses many of the questions which are asked on this subject for retrofitting existing plants and for designs of new coal-fired plants. One particular area for discussion is coal gasification for existing plants with package boilers. Estimated capital and operating costs are reviewed for various size ranges applicable to the industrial power plant.
Evaluation Program for New Industrial Gas Turbine Materials
Authors: Just Ch. , Franklin C. J.
Published: November 2010

The need for a thorough and systematic standard evaluation program for new materials for modern industrial gas turbines is shown by several examples and facts. A complete list of the data required by the designer of an industrial gas turbine is given, together with comments to some of the more important properties. A six-phase evaluation program is described which minimizes evaluation time, cost, and the risk of introducing a new material.
Prediction of Torsional Strength of Tubes
Authors: Reiland R. F.
Published: November 2010

A simplified analysis technique has been developed to predict torsional strength of tubes or shafts including plastic buckling limits and effects of plastic redistribution through the tube wall. Buckling predictions employ well-known formulas and concepts, but are combined in a unique procedure which provides improved accuracy over present known techniques. It was concluded that Batdorf’s equation, previously considered applicable only to relatively short tubes, is also applicable even to long slender tubes when wall stress redistribution effects are included. It was further concluded that Gerard’s recommendations for plasticity reduction factor were very accurate when obtained from compression stress-strain curves through application of the maximum shear stress theory in plasticity. Experimental verification of torsional strength prediction methods is needed for alloys other than aluminum, especially at elevated temperatures.
Further Developments in the Aerodynamic Analysis of Unsteady Supersonic Cascades—Part 2: Aerodynamic Response Predictions
Authors: Verdon J. M.
Published: November 2010

This paper is the second of a two-part report on a theoretical analysis of the aerodynamic response to an oscillating supersonic cascade in subsonic axial flow. Supersonic resonance criteria are discussed and lead to the distinction between subresonant and superresonant cascade motions. Numerical predictions, based on the unsteady solution reported in Part 1, are presented for two typical cascade configurations. These reveal the possibility of both subresonant and superresonant single-degree-of-freedom torsional instabilities. Subresonant instabilities occur over a broad range of frequencies and interblade phase angles, whereas superresonant instabilities occur only over a narrow range of such cascade parameter values. For a given blade motion frequency and free-stream Mach number, it appears that the least stable condition will usually lie in the subresonant region.
Catalytic Combustion Modeling; Comparisons With Experimental Data
Authors: Cerkanowicz A. E. , Cole R. B. , Stevens J. G.
Published: November 2010

A model for catalytic combustor operation is described for a well-mixed plug-flow reactor. Heterogeneous and homogeneous reactions are considered with heat and mass transfer handled using transport coefficients. Gas velocity is allowed to vary axially and heat conduction in the catalyst bed is included. Computer solutions were obtained for axial profiles of conversion, gas and substrate temperature, velocity, and pressure. Model predictions are compared to catalytic combustion data, showing excellent agreement. Catalytic light-off, hysteresis, and homogeneous contribution are discussed. Data from a hybrid combustor developed in this laboratory are analyzed using a simplified model.
A Potential Low NOx Emission Combustor for Gas Turbines Using the Concept of Hybrid Combustion
Authors: Mumford S. E. , Hung W. S. Y. , Singh P. P.
Published: November 2010

An experimentally verified NOx emission model has been described previously to predict accurately the NOx emission characteristics of conventional gas turbine combustors as well as laboratory scaled premixed combustor. Experimental data and analyses indicated that a hybrid combustor, which utilizes features of both the conventional and the premixed combustors, has the potential to be a viable low NOx emission combustor. Initial calculations indicated low NOx emission levels for the hybrid combustor. This hybrid combustion concept was tested in the laboratory. The measured NOx emissions from this laboratory-scaled hybrid combustor were in excellent agreement with the analytical predictions. The emissions of carbon monoxide and unburned hydrocarbons were also measured. It has been concluded from an analysis of the measured data that a gas turbine combustor, designed with the hybrid combustion concept, has the best potential to be a near-term viable combustor in meeting the EPA proposed gas turbine emission regulations. The experimental effort thus far has focused on the emission characteristics. Other areas of the design, such as the vaporization of liquid fuels, require additional development work prior to the incorporation of this concept into a viable system for an engine application.
The Effect of Fin Geometry and Manufacturing Process on Ceramic Regenerator Thermodynamic Performance
Authors: Fucinari C. A.
Published: November 2010

The essential parameters required for accurate regenerator thermodynamic performance prediction are the basic heat transfer and pressure drop characteristics of the matrix fin configuration. The basic heat transfer and pressure drop characteristics evaluated in a “shuttle rig” of the existing “state of the art” matrix fin configurations will be presented. Based on these data, the effect of fin geometry and manufacturing process on ceramic regenerator performance will be discussed. In addition, a simplified analysis for estimating the effect of alterations in package size and/or fin parameters on regenerator performance will be presented.
Performance of a Spray Pond for Nuclear Power Plant Ultimate Heat Sink
Authors: Schrock V. E. , Trezek G. J. , Keilman L. R.
Published: November 2010

Spray ponds have become an attractive method of providing the “ultimate heat sink”, i.e., the assured means of dissipating heat from a nuclear power plant. Two redundant spray ponds were the choice for this service in the Rancho Seco Nuclear Generating Station owned by Sacramento Municipal Utility District. This paper describes the results of full scale field tests of the Rancho Seco ponds which were conducted to verify the thermal performance, drift loss characteristics, and the capability to sustain the cooling requirements for a period of 30 days following a loss-of-coolant accident (LOCA). Correlations of local and average nozzle efficiency and of the drift loss are presented. A computer code was developed for the transient thermal performance of the pond. After verification the code was used to predict performance following LOCA under adverse meteorological conditions based on weather records.
Demonstration of Ceramic Design Methodology for a Ceramic Combustor Liner
Authors: Trantina G. , Grondahl C.
Published: November 2010

Successful application of ceramics in the gas turbine environment involves brittle material design and analysis, unique material properties, and laboratory demonstration of components. Alternative ceramic structures for application in a hybrid ceramic-metal combustion system were considered. Thermal stresses and probabilities of failure were calculated for tube, ring, and stave designs. The stress levels are relatively low for axial and radial temperature gradients in all 6 in. (152 mm) diameter combustors. Scaling to larger sizes is also considered. A hot streak temperature distribution resulted in stresses in the stave and tube which were three times the stresses in the ring design. Bend specimens were cut from one end of a 6 in. (152 mm) diameter, 10 in. (254 mm) long REFEL silicon carbide tube to assure a representative flaw distribution. Strength, strength scatter, and strength degradation were evaluated at 2200°F (1200°C) and were incorporated in the stress analysis. A low probability of failure was predicted. The REFEL tube was tested in the hybrid ceramic-metal combustion system at gas temperatures in excess of 2660°F (1460°C), 16 atm pressure, and 6.9 lb/s (3.1 kg/s) mass flow while burning No. 2 fuel oil. Successful ceramic performance was demonstrated at 2000°F (1090°C) steady state and at 2000°F (1110°C) per minute shutdown cooling rate.
Ultrasonic Monitoring of Growth of Part-Through Thickness Defects at 290°C
Authors: Hartung H. F. , Burns D. J. , Pindera J. T.
Published: November 2010

This paper discusses the design and calibration of an ultrasonic transducer for continuously monitoring the subcritical growth of internal, part-through thickness defects in steel piping operating at temperatures up to 300°C.
A Recommended Design Approach for Breeder Reactor Cover Gas Seals
Authors: Sharbaugh J. E.
Published: November 2010

Technological progress requires that lessons learned in initial design efforts be incorporated into the following design effort. One area where improvement can be made is in the design of elastomer seals for containment of breeder reactor cover gases. Liquid metal fast breeder reactor (LMFBR) vessels, unlike PWR’s, operate at a very low pressure. The reactor cover gas may be maintained at a pressure of less than 1 psia. This low pressure level and moderate temperatures of the vessel head-mounted refueling and monitoring equipment permit the use of elastomer seals in this equipment to contain the cover gas. Existing seal designs are based on a conservative design philosophy which was established in the late 1960’s when the FFTF project was in its formative stages. The information gained in the design and development of LMFBR seals during the past decade indicates that some changes in the approach to seal design could result in improved seals and reduced downtime for seal maintenance. This document presents the design approach currently used for cover gas seals, and points out how improvements can be made based on today’s knowledge of breeder reactors and elastomer seals. A suggested new seal design concept is presented which may better meet the LMFBR commercial program needs. The basic assumption used to design cover gas seals conservatively states that elastomer seals, even when new, can leak, and primary consideration must be given to preventing the outflow of radioactive cover gas. The suggested new design concept acknowledges that elastomer seals are effective, and the primary consideration should be one of controlling the gases which permeate through the elastomer seal material. Finally, information which was obtained from the cover gas seal development program for FFTF, which is of value to all LMFBR equipment designers, is summarized.
Water Production from Exhaust Gases of Steam Power Plants
Authors: Papageorgiou N.
Published: November 2010

An attractive and nontraditional method for water production is presented in this paper. The proposed method is to condense the exhaust gases of the natural gas fired steam generators of power plants. In order to achieve this, it is necessary that modification of the convectional steam power cycles be accomplished without sacrificing the efficiency of the power plants. An investigation and modification of the power cycles is proposed. Economic aspects are also considered.
Calculational Modeling of Explosive Fracture and Permeability Enhancement
Authors: Butkovich T. R. , Burton D. E. , Bryan J. B.
Published: November 2010

With its underground explosion computer codes SOC and TENSOR, the Lawrence Livermore Laboratory is developing a capability for computer code prediction of fracture intensity and permeability enhancement far from a free face. Because the codes calculate fracture and not permeability, one must relate experimental measurements to a calculable parameter for fracture. High-explosive experiments in a coal outcrop and a multiple-charge experiment in a coal seam were designed to provide the needed data. Fracture intensity observed around the explosion centers is shown to be related to a calculated damage parameter εf. This parameter is actually the total failure-induced deviatoric strain. Intrinsic permeability, determined from hydraulic conductivity and calculated from results from slug tests in wells near the explosion, correlates at least qualitatively with the calculated residual tensile-fracture porosity, πf. An important observation is that no tensile failure occurs for some distance from the explosion-formed cavity when spherical charges are employed, whereas, tensile failure occurs near the cavity wall when cylindrical charges are used.
Effects of Strain Hardening on Rock / Bit-Tooth Interaction
Authors: Pan R. B. , Cheatham J. B.
Published: November 2010

The rock/bit-tooth interaction problem has been approximated previously by plasticity analysis of a wedge indenting a half-space. In the previous work the rock, under high confining pressure, was assumed to be perfectly plastic. In the present paper, an approximate method is presented for including the effects of strain hardening of the rock on the pressure distribution at the rock bit-tooth interface. The slip-line field for the perfectly plastic solution is used as a basis for applying corrections for the strain-hardening effect.
Limit Analysis and Design of a Semi-Submerged Concrete Hull for an Ocean Thermal Differences Power Plant
Authors: Dzialo F. J. , Heronemus W. E.
Published: November 2010

Utilizing the concepts of limit analysis, and ultimate strength of concrete, a design approach for large diameter immersed reinforced concrete cylindrical hulls has been developed. The method is applied to the design of a semi-submerged ocean thermal differences power plant. For the structure under consideration which consists of an outer and inner hull, separate operating and maintenance conditions were assumed for design. Equilibrium equations, and an iteration method to determine plastic moments, axial forces and shears corresponding to a collapse condition have been developed. Computer results for the outer and inner hull are tabulated for the two loading conditions based on design thickness of 3 ft. For a given thickness, details of reinforcing are given, and an admissible interaction diagram for moment and axial load to satisfy the various loading conditions is presented.
Measurement of Two-Dimensional Periodic Flow With a Cobra Probe
Authors: Senoo Y. , Kita Y. , Ookuma K.
Published: November 2010

Three semiconductor pressure transducers were inserted into a cobra probe to measure instantaneous condition of flow at the exit of a pump impeller. As it was difficult to calibrate a probe in a two-dimensional periodic flow which was similar to the periodic flow to be measured, the authors used the probe assuming that the steady flow characteristics were valid and examined the results in several ways. The results at different pump speeds satisfied the similarity law of flow from the impeller, and it was concluded that the time response of the probe and pressure transducer system was satisfactory. Almost identical results were obtained regardless of the orientation of the probe, and it was concluded that the calibration curve at steady state was applicable to the unsteady state. Finally, the static pressure calculated from the probe output agreed with the wall pressure which was directly measured with a semiconductor pressure transducer. The authors believe that the three steps are sufficient to prove that the results obtained with the probe are reliable and the probe system is suitable for measurement of periodic flow at the exit of impeller of a pump.