bluuebunny/crossref_metadata_2025 huggingface dataset:
Constitutive Relationships for the Time-Dependent Deformation of Metals
Authors: Ponter A. R. S. , Leckie F. A.
Published: November 2010

The paper discusses the constitutive relations for the inelastic deformation of a polycrystalline metal at high temperature. Commencing from a description of a dislocation structure in terms of strain hardening and thermal softening, the general form of the constitutive relation is developed in terms of a potential function. The existence of a stationary state potential is established and generalizations of isotropic and kinematic hardening are described.
Development of Constitutive Relation for Plastic Deformation From a Dislocation Model
Authors: Gittus J. H.
Published: November 2010

Further analysis of a model in which creep is attributed to the movement generation, immobilization, and recovery of dislocations has permitted the anelastic (recoverable) component of strain to be calculated. The earlier conclusions are unaffected by this refinement and so the model equations continue correctly to predict the effects of raising, reducing, removing and reversing the stress during the creep of a range of materials including stainless steel, zirconium alloys, copper, tungsten, nickel, and aluminum. In addition, however, it is now (correctly) predicted that removal of a tensile stress will permit compressive creep to occur, producing an anelastic strain whose magnitude increases towards an upper asymptote as the magnitude of the prior tensile stress increases. Anelasticity is found to become an increasingly large proportion of the total strain at low stresses: the model predicts this. It also predicts the pattern of behavior observed in “stress-dip” tests: in particular that there is a critical magnitude of stress reduction which causes momentary cessation of creep.
An Inelastic Constitutive Model for Monotonic, Cyclic, and Creep Deformation: Part I—Equations Development and Analytical Procedures
Authors: Miller A.
Published: November 2010

A new, unified model simulates many of the structurally significant deformation phenomena associated with both creep and short-time plasticity, including cyclic hardening/softening, Bauschinger effect, strain-rate effects, and annealing, among others. It is phenomenological and macroscopic in nature, but is strongly related to the underlying microscopic physical mechanisms. It consists of a single hyperbolic sine strain-rate equation, plus two work-hardening/recovery equations for the rates of change of the two history variables. The derivation, behavior, and use of the model are explained, and the procedure for calculation of materials constants from standard test data is given. Comparisons are made with some other current strain-rate formulations.
A Generalization of Plastic Flow Theory With Application to Cyclic Hardening and Softening Phenomena
Authors: Eisenberg M. A.
Published: November 2010

A generalization of current theories of plasticity is developed. The theory, applicable to arbitrary multiaxial loading histories, requires a strain controlled uniaxial cyclic experiment to specify the material parameters. In its general form, deformation, translation and rotation of the yield surface are permitted. Detailed calculations are carried out for the simple model of combined isotropic and kinematic hardening of an initial Mises yield surface. This model is shown to provide a quantitative representation of the transient uniaxial cyclic hardening process for type 304 stainless steel at elevated temperature. Implementation of the theory in current FEM structures codes should be straightforward.
A Cumulative Damage Rule Based on the Knee Point of the S-N Curve
Authors: Subramanyan S.
Published: November 2010

Making use of a set of isodamage lines, a fresh concept for predicting the fatigue life, under variable amplitude loading, is presented. It is assumed that all isodamage lines converge at the knee point of a S-log N diagram. The life predictions based on this concept are closer to the experimental data than given by Miner’s linear damage rule. The concept is verified with the step-test data obtained on unnotched C-35 steel specimens in rotary bending. Several other reported experimental data in rotary bending tests also confirm the reliability of this simple damage rule.
Shear Difference Method and Application in Orthotropic Photoelasticity
Authors: Knight C. E. , Pih H.
Published: November 2010

The shear difference method is developed here for application to orthotropic photoelasticity problems. The two-dimensional stress-optic law which was presented in another paper is used. The stress-optic law provides two equations for the three plane stress components and the shear difference method may be used to obtain the third relation. This paper presents the development of the general orthotropic shear difference method for any material orientation. For orientations aligned with the material principal directions, the relations are identical to the isotropic shear difference method. The solution of an orthotropic tensile strip with a central hole demonstrates application of the orthotropic shear difference method and further confirms the orthotropic stress-optic law. Good agreement was found between the photoelastic and theoretical solutions.
Parameters Affecting the Velocity of Particles in an Abrasive Jet
Authors: Wolak J. , Worm P. , Patterson I. , Bodoia J.
Published: November 2010

Silicon carbide particles, mesh 60, were introduced at a known time-rate (wp) into an air stream flowing at a time-rate (wa) through a parallel sided nozzle of circular cross-section. Particle velocity (Vz) within the resulting abrasive jet was measured by means of a specially adapted streaking camera technique. Vz was found to be a function of the nozzle length (L), of the distance (z) from the nozzle exit, of the radial position (r) within the jet, and of the loading ratio (wp/wa). The results indicate that the parameters Vz, L, z, wa and wp are of primary importance in studies of abrasive erosion as well as in the design and operation of air-powered sandblasting equipment.
Cyclic Plasticity for Nonproportional Paths: Part 2—Comparison With Predictions of Three Incremental Plasticity Models
Authors: Lamba H. S. , Sidebottom O. M.
Published: November 2010

Experiments that demonstrate the basic quantitative and qualitative aspects of the cyclic plasticity of metals are presented in Part 1. Three incremental plasticity kinematic hardening models of prominence are based on the Prager, Ziegler, and Mroz hardening rules, of which the former two have been more frequently used than the latter. For a specimen previously fully stabilized by out of phase cyclic loading the results of a subsequent cyclic nonproportional strain path experiment are compared to the predictions of the above models. A formulation employing a Tresca yield surface translating inside a Tresca limit surface according to the Mroz hardening rule gives excellent predictions and also demonstrates the erasure of memory material property.
Adhesive Bond Stresses and Strains at Discontinuities and Cracks in Bonded Structures
Authors: Hart-Smith L. J.
Published: November 2010

This paper presents analysis procedures to be used for analyzing adhesively bonded structures containing cracks or discontinuities in the metal elements. The analyses are performed for a range of disbonds in each of four basic problems for stiffened structures: (1) stiffener broken at one station or with a finite length removed, sheet intact, (2) stiffener intact, sheet completely broken, (3) one-bay sheet crack, stiffeners intact, and (4) two-bay sheet crack, stiffener intact. Separate failure modes of disbond under shear loads, stiffener yield, and sheet fast fracture are investigated. The solutions are essentially planar (two-dimensional) and such three-dimensional effects as stiffener or sheet bending and peel stresses in the adhesives are not accounted for. The paper contains parametric studies for the governing variables and excellent agreement with test is demonstrated for the available test data (one-bay sheet crack). The analyses are approximate and not of universal applicability, but are simple to use with either pocket electronic calculators or digital computers. Known limitations of the theory are confined to situations in which the adhesive stresses are small and widespread rather than high and concentrated in a small identifiable zone adjacent to the discontinuity. The conconclusion drawn from the examples investigated is that disbonds can be initiated relatively easily at discontinuities in the metal structural elements, because the bond is very stiff, and that care is needed in proportioning the structural elements to control this potential problem. The analyses indicate also that the initial disbond is usually self-arresting and is not catastrophic. Higher loads are usually needed to propagate the disbond and, eventually, induce complete failure which is triggered by stiffener yield or fast fracture of the sheet at the crack tips. The sample cases point to the need to account for adhesive plasticity, stiffener yielding, and changes in load path as disbonds propagate.
The Effect of Adhesive Layers on the Fracture of Laminated Structures
Authors: Gecit M. R. , Erdogan F.
Published: November 2010

In this paper the effect of the thickness and the elastic properties of the adhesive layers in laminated structures is considered. The structure is assumed to consist of two sets of periodically arranged dissimilar layers which may contain cracks perpendicular to the interfaces. The crack problem is solved under the assumption of plane strain or generalized plane stress and by using two different models for the adhesive layers. In the first model the adhesive layer is approximated by a combination of tensile and shear springs. In the second the adhesive layer is considered to be an elastic continuum, hence involving no approximating assumptions. The results regarding the stress intensity and stress concentration factors obtained from these two models and that found by ignoring the adhesive layers are presented and some comparisons are made.
Stress-Strain Analysis of Cyclic Plastic Bending and Torsion
Authors: Dowling N. E.
Published: November 2010

Analysis of stresses, strains, and damping energies is considered for cyclic loading of simple geometries. For beams under pure bending and for circular shafts under torsion, it is shown that cyclic loading may be handled by analysis that differs from that applicable to monotonic loading only by the substitution of a cyclic stress-strain curve. Analysis and experiment are successfully compared for rectangular beams of an alloy steel.
Comparison of Dynamic Tear and Charpy-V-Notch Impact Properties of Plate Steels
Authors: Wilson A. D.
Published: November 2010

The increasing interest in the Dynamic Tear (DT) test for use in measuring the fracture resistance of steels in both quality control and research testing, invites a comparison to the commonly used Charpy-V-notch (CVN) impact test. The DT and CVN properties of 57 steel plates of various grades are compared in this survey. The investigation covered ASTM carbon steel grades A-36, A516, A537; ASTM alloy steel grades A533-B, AB42, A43; and other steels such as HY-130, ABS-E, and a C-Mn-Cb type. Graphical and statistical correlations were established between various DT and CVN properties including upper shelf energy, fracture appearance and mid-energy transition temperatures. These features were then compared to the nil ductility temperature (NDT). Certain of the correlations appear useful enough to allow casual prediction of DT behavior from CVN testing.
Notch Effects, Stress State, and Ductility
Authors: Agogino Alice M.
Published: November 2010

A review of the literature on testing of notched specimens is provided with emphasis on short-term notched bar tension tests. The effects of notch geometry, stress state, and smooth-bar tensile properties on notched ductility, notch sensitivity, and mode of fracture are discussed. For design against failure due to notch weakening, a simple criterion based on a limiting value of notched ductility is proposed. Notched ductility for the metals considered in this study, can be approximated by the reduction in and from a smooth tension test divided by a tensile stress triaxiality factor that is proportional to the ratio of hydrostatic to octahedral shearing stresses associated with the notch.
An Analysis of High Temperature Metal Creep—Part I: Experimental Definition of an Alloy
Authors: Laflen J. H. , Stouffer D. C.
Published: November 2010

The general objective of the research reported is to develop a constitutive theory for the elevated temperature behavior of Wrought Udiment 700. A major part of this work was to establish a data base for this material and evaluate the observed response using many of the modern approaches to constitutive modeling. The phenomenological description of the material was evaluated by a series of load rate, strain rate, and creep tests. These data clearly showed the existence of a finite primary creep rate response function similar to the minimum creep rate function. Also the concept of material stress rate coordinate is introduced to describe the change from the primary to the minimum creep rate.
Crack Growth Behavior in Alloy 718 at 425°C
Authors: Sadananda K. , Shahinian P.
Published: November 2010

Subcritical crack growth behavior in Alloy 718 was studied at 425°C under static, cyclic, and combined loads. The results are analyzed using linear elastic fracture mechanics. Crack growth was shown to be cycle-dependent at all stress intensities at this temperature and hold times up to 10 min have no effect on the crack growth rates. On the other hand, crack growth is shown to occur readily under static loads at stress intensities less than half of the fracture toughness value. Comparison of the present results with those published in the literature showed that while crack growth is cycle-dependent at 425°C and time-dependent at 650°C, at an intermediate temperature, 540°C, it is time-dependent at low stress intensities and cycle-dependent at high stress intensities. Extrapolation of the present data shows that crack growth under static load could occur at temperatures above approximately 350°C and this may be a limiting factor for Alloy 718 for some of its high temperature applications.
Viscoplastic Constitutive Equations for Copper With Strain Rate History and Temperature Effects
Authors: Bodner S. R. , Merzer A.
Published: November 2010

Elastic-viscoplastic constitutive equations based on a single internal state variable which is a function of plastic work are used to calculate the response of copper to a six decade change of strain rate over a range of temperatures. Calculations were performed for the conditions of an experimental program on copper by Senseny, Duffy, and Hawley, namely, temperatures ranging from 77°K to 523°K and strain rate jumps from 2 × 10−4sec−1 to 3 × 102sec−1 at three strain levels. The computed results are in good agreement with the experiments and show similar strain rate and strain rate history effects. Relations are obtained for the temperature dependence of certain parameters in the equations which indicate correspondence between plastic working and temperature and between strain rate sensitivity and temperature.
Fatigue Under Wide Band Random Stresses Using the Rain-Flow Method
Authors: Wirsching P. H. , Shehata A. Mohsen
Published: November 2010

A fatigue design procedure is proposed for the structural elements subjected to a stress process, modeled as stationary wide-band gaussian. This procedure, restricted to high cycle fatigue design, uses available constant amplitude material fatigue data and a modified, probability based, Palmgren-Miner (PM) rule. Statistical uncertainty in fatigue behavior and nonstatistical uncertainty in the PM rule are implicitly accounted for by treating the PM index at failure as a random variable. The rain flow method of counting stress cycles is used. The fatigue design algorithm requires only that the RMS and irregularity factor of the stress process be specified in addition to the constant amplitude S-N curve for the material.
Erosive Effects of High Pressure and High Temperature Gases on Steel
Authors: Alkidas A. C. , Christoe C. W. , Caveny L. H. , Summerfield M.
Published: November 2010

An experimental study is being conducted to determine the thermochemical mechanisms by which short duration pulses (1 to 2 ms) of high pressure and temperature gases erode steel. A ballistic compressor is used to generate the desired test gas conditions. The erosion of steel by oxygen-containing gases (e.g., air, O2/N2 mixtures) was found to be controlled by surface chemical reactions of oxygen. The erosion is linearly proportional to the oxygen mole fraction of the O2/N2 mixture. SEM examination of surfaces eroded by air, H2 and CO showed the formation of scales resulting from gas/surface interactions. It is proposed that, in general, erosion of steel results from the rapid formation of oxides on the surface followed by the removal of the oxides by the aerodynamic forces of the flow.
Further Dynamic Finite Element Analysis of the Tapered DCB Specimen
Authors: Urabe Y. , Kobayashi A. S. , Emery A. F. , Love W. J.
Published: November 2010

A dynamic finite element code was used to compute the dynamic stress intensity factors and crack arrest stress intensity factor which are related to the crack run-arrest response in a tapered double cantilever beam (DCB) specimen machined from A533B steel. Measured crack velocities of a fracturing tapered DCB specimen were used to prescribe a crack motion under both fixed grip and variable loading conditions at the two loading pins. Numerically and experimentally determined dynamic strains were compared at three locations on the fracturing tapered DCB specimen. This comparative study showed that the fixed grip condition modeled the actual dynamic state well and that the crack arrest stress intensity factor, KIa, computed on the bases of fixed grip and variable loading conditions differed by a factor of approximately 0.6.
Improvements to the Ainley-Mathieson Method of Turbine Performance Prediction
Authors: Dunham J. , Came P. M.
Published: November 2010

In 1951 Ainley and Mathieson published a method of predicting the design and off-design performance of an axial turbine (British ARC, R & M 2974). The flow and hence the losses were calculated at a single “reference diameter” for each blade row. This method has been widely used ever since. A critical review of the method has been made, based on detailed comparisons between the measured and predicted performance of a wide range of modern turbines. As a result, improvements have been made in the formulas for secondary loss and tip clearance loss prediction. The accuracy of the improved method has been assessed. Despite its relatively simple approach, it is believed that it will remain of great value in project work and preliminary design work.
Aerodynamic Stability of Branched Diffusers
Authors: Ehrich F. F.
Published: November 2010

A systematic analysis is made of the potential instability of branched diffuser systems such as are inherent to the annular combustor systems of gas turbine engines. The system is modeled to include diffusion in each branch with pressure recovery characteristics which are a simple function of the fraction of total flow into the branch. Also included in each branch is a volume (i.e., an accumulator) and a resistance representing the combustor shells before the two branched streams rejoin. Analysis of the system equations is carried out in two perspectives. First, the equations are linearized and simple generalized criteria for stability are derived. Then the full nonlinear equations are programmed for digital computation in a form where they can be integrated with respect to time, and the full dynamic behavior of flows and pressure described. The computation is carried out several times for system variations of shell resistance, accumulator volumes, and diffuser characteristics, so that general conclusions may be drawn of the effects of these parameters on the frequency, wave form, and amplitudes of the systems’ oscillations.
Intra-Stator Transport of Rotor Wakes and Its Effect on Compressor Performance
Authors: Kerrebrock J. L. , Mikolajczak A. A.
Published: November 2010

The stagnation temperature profiles which have been observed recently downstream of the stators in high Mach number compressor stages are shown to be due to transport of the rotor wakes across the main streamlines during their passage through the stator. The rotor wake fluid has energy in excess of the inviscid flow, and it is collected by the pressure side of the stator. A wake transport theory is presented, which connects the temperature profile to the rotor blade loss factor, and so provides a new method for determination of the losses in a rotor under actual operating conditions. The theory compares favorably with a special helium-tracer experiment designed to check it, as well as with temperature measurements in two high Mach number stages.
Comparison of Performance of Supersonic Blading in Cascade and in Compressor Rotors
Authors: Mikolajczak A. A. , Morris A. L. , Johnson B. V.
Published: November 2010

Reduction of engine weight and engine specific fuel consumption is a continuing goa of jet engine designers. An attractive approach is through the development of efficient, high-tip speed compressors operating with supersonic relative inlet Mach numbers. For these compressors, selection of highly efficient supersonic blading is required. Although the evaluation of new blade geometries can be obtained more conveniently from supersonic cascade tests rather than compressor, it has not yet been adequately established that good correspondence exists between cascade and compressor tests. The paper shows that such correspondence exists. In this paper performance of three airfoil shapes tested in cascade is briefly discussed and compared to the performance of similar airfoils tested in a rotor. A description of a supersonic tunnel is given and precautions necessary to obtain meaningful data are stressed. Good correspondence obtained between the cascade and rotor results is discussed.
Design of Cascades for Incompressible Plane Potential Flows With Prescribed Velocity Distribution
Authors: Schwering W.
Published: November 2010

A method of calculation in designing two-dimensional cascades with given velocity distribution is described. An iterative method of the solution for the integral equation to determine the coordinate function for the blade profile is presented. A parametric formulation for the surface velocity distribution is developed. Some design examples for deceleration cascades with given flow angles and prescribed velocity distribution are discussed. Calculations of the boundary layers along the surfaces of the airfoil and cascade loss coefficients are made in order to obtain information on the quality of cascades designed by this method. Proceeding from the results of boundary layer calculations, it should be possible to further improve the parametric formulation for the surface velocity distribution and in this way prescribe better or even “optimum” velocity distributions.
The Development of a Turbine Wheel Design Criterion Based Upon Fracture Mechanics
Authors: Brandt D. E.
Published: November 2010

The development of a design criterion based upon fracture mechanics is described in detail. Specifically treated are crack tip plastic zone corrections, proximity effects on a crack adjacent to a free surface, buried and surface cracks, subcritical crack growth, and the effects of a biaxial stress state. Also included is the application of the criterion in predicting several rotor failures.
Stress Distributions in Some Diesel Engine Crankshafts
Authors: Fessler H. , Sood V. K.
Published: November 2010

Models of single throws of overlapped crankshafts have been loaded by free and restrained torsion, radial and tangential forces and bending moments, and by axial tension. Stress distributions in the fillets have been obtained by frozen stress photoelasticity. Some peak stresses have been measured with strain gauges. Results, expressed as multiples of convenient nominal stresses, are compared with predictions from published work. The maximum stresses due to any combination of firing force and free torsion were computed and it is shown how the effects of other loading modes may be included.
Nonradioactive Tracer for Performance Tests of Steam Turbines in PWR Systems
Authors: Deming N. R. , Feldman R. W.
Published: November 2010

This paper reports on the experience gained by the authors in the use of a nonradioactive sodium tracer in limited-scope testing in power plants with nuclear steam supply systems. It shows this method is applicable to full-scale ASME Code testing of these units. Problems encountered in obtaining and handling water samples are discussed. The theory of the tracer method is reviewed and expanded application is explained.
Experience With Throat-Tap Nozzles for Accurate Flow Measurement
Authors: Cotton K. C. , Carcich J. A. , Schofield P.
Published: November 2010

During the past 10 years considerable experience has been gained in the use of ASME throat-tap nozzles for accurate flow measurement. Numerous precision calibrations have established turbulent flow coefficients up to a throat Reynolds number of 6.6 million. These results verify flow coefficients calculated from boundary-layer analysis.
Axial Flow Compressor and Turbine Loss Coefficients: A Comparison of Several Parameters
Authors: Brown L. E.
Published: November 2010

Many loss parameters are used in the turbomachinery field for correlating the effects on losses of numerous geometric and aerodynamic variables associated with blade rows. The parameter most common to these correlations is the ratio of a loss parameter to a velocity parameter, here called the loss coefficient. Such loss coefficients of different forms used for compressors by Howell and the NACA and those used for turbines by Ainley and Soderberg, plus an additional one, are compared explicitly for possible use in both compressors and turbines. Over a range of Mach numbers, loss coefficient values are compared with loss levels fixed and for representative blading cascade test data, and pressure recoveries and stage efficiencies are compared with loss coefficient values fixed. It is shown that for a low Mach number the different parameters are equal and interchangeable; however, as the Mach number increases, differences appear and grow larger, so that a given combination of loss coefficient value and Mach number implies different entropy-rise values depending upon which parameter is being used. The criteria used here for comparing the different parameters are that one loss coefficient is better than another a– if its loss coefficient values corresponding to test data vary less over a significant range of Mach number, and b– if the stage efficiency implied by a fixed loss coefficient value varies in a more realistic way over a range of Mach number. The Soderberg parameter was found to be better for both compressors and turbines than the other loss coefficients investigated.
An Approximate Analysis of the Unsteady Lift on Airfoils in Cascade
Authors: Henderson R. E. , Horlock J. H.
Published: November 2010

An approximate analysis is presented for determining the unsteady lift on airfoils in moving cascades, subject to disturbances in the inlet axial flow. The equations of motion are averaged across the pitch, and the mean pressure in each channel and the pressure difference across it are obtained. The lift on a reference blade dividing two blade channels is then estimated. The analysis is limited to flows in which the frequency parameter based on blade pitch is small, and to blading of low lift coefficient. Comparisons are given with earlier analyses, for flow past isolated airfoils (Sears), for quasi-steady flows through cascades (Gearhart, et al.), and for flow through an actuator disk of small blade chord and flow through cascades of flat blades (Whitehead).
Formation and Control of Oxides of Nitrogen Emissions From Gas Turbine Combustion Systems
Authors: Singh P. P. , Young W. E. , Ambrose M. J.
Published: November 2010

Results of an investigation into the levels of oxides of nitrogen in Westinghouse gas turbine exhausts are presented. Various methods of controlling the amounts of these emissions were considered. The oxides of nitrogen were reduced most effectively by lowering the maximum flame temperature. This was done by either leaning the primary zone of the combustor, by water injection in the primary zone, or by using vitiated combustion air. Reductions in NOx levels to 15 percent of original values were achieved.
Comparison of Nuclear Power Plants With Closed-Cycle Helium Turbine and With Steam Turbine Cycle for Combined Power and Steam Generation
Authors: Bammert K. , Buende R.
Published: November 2010

The heat of a helium-cooled reactor can be used for combined power and steam generation either in a closed-cycle helium turbine system, the so-called single-cycle system, or in a two-cycle system which consists of a helium cycle and a secondary steam turbine cycle. The optimum data for the two systems are determined within the same range of general parameters—electric power output and quantity and quality of the steam produced—as functions of the special parameters of each particular cycle system. A method of comparing different power plant systems is shown. With this method it is possible to determine those ranges in which the efficiencies achieved with one system are higher than those obtained with the other. It is described in which way the dividing line between such ranges depends on the special parameters of the cycles. The comparison shows that the single-cycle system offers advantages.
Low Pressure Ratio Fan Noise Experiment and Theory
Authors: Metzger F. B. , Hanson D. B.
Published: November 2010

The Q-FAN™, a new low pressure ratio, low noise propulsor, is currently under intensive development. Since the operating regime of the Q-FAN differs from that of the turbofan, the dominant noise sources also differ. This paper includes a summary of the results of extensive noise tests on a Q-FAN model, a discussion of the sources of various components of measured fan noise, and the results of analytical studies using a new theory to define minimum noise fan configurations.
ASME Steam Turbine Code Test Using Radioactive Tracers
Authors: Cotton K. C. , Schofield P. , Herzog W. G.
Published: November 2010

The experience gained from conducting an ASME Steam Turbine code testing using radioactive tracers has confirmed the encouraging results obtained during initial feasibility studies. The test also demonstrated the practicability of this method for testing steam turbines operating in the wet region from steam supplied by light water nuclear reactors. Recommendations for the location and installation of the sample and injection points are included, together with an outline of the equipment and procedures used during the testing.
A Wake and an Eddy in a Rotating, Radial-Flow Passage—Part 2: Flow Model
Authors: Moore J.
Published: November 2010

Rotational and three-dimensional terms are added to a strip-integral method for predicting the behavior of turbulent boundary layers. The secondary flow in the boundary layers is analyzed, and a theory for the momentum transport in the corner regions is used to couple the development of all the boundary layers. Simple assumptions for the potential flow and wake regions complete a model which allows the calculation of the whole channel flow, with only the specification of the inlet boundary layers.
Transient Considerations of Flat-Plate Solar Collectors
Authors: Klein S. A. , Duffie J. A. , Beckman W. A.
Published: November 2010

The effects of thermal capacitance in the modeling of the performance of a flat plate solar collector have often been neglected because of the computation involved. But because the solar collector is inherently exposed to continuously variable weather conditions, capacitance effects may be significant. To investigate these effects, three different models of flat-plate collectors have been investigated. The first, a quasi-steady-state model, simulates the performance of a collector of zero capacitance. The second model accounts for capacitance effects by assuming that a single value of thermal capacitance can be determined for the collector as a unit. The third model divides the collector into many isothermal segments, or nodes. For all three models the heat transfer coefficients are calculated as a function of operating conditions. The results show that, when hourly meteorological data are used, the zero-capacitance model is adequate.
Corrosion and Deposits From Combustion of Solid Waste: Part 2—Chloride Effects on Boiler Tube and Scrubber Metals
Authors: Krause H. H. , Vaughan D. A. , Miller P. D.
Published: November 2010

Chlorides play an important role in corrosion of heat-transfer surfaces and wet-scrubbers in municipal incinerators. The nature of the deposits and the extent of corrosion have been investigated in a combined field and laboratory study. Corrosion by flue gases and accumulated deposits has been measured by probes exposed in large municipal incinerators. The corrosion rates of various metals by incinerator scrubber waters also have been determined. Parallel laboratory experiments were conducted to provide additional data under controlled environments for interpretation of corrosion reactions. General surface wastage, pitting, or stress-corrosion cracking was observed in different samples, depending on the exposure conditions.
The Cause of Tone Generation by Aero-Engine Fans at High Subsonic Tip Speeds and the Effect of Forward Speed
Authors: Cumpsty N. A. , Lowrie B. W.
Published: November 2010

Modern aero-engine fans (without inlet guide vanes) produce a tone at blade passing frequency by interacting with the inlet flow distortion. Because the distortion is altered by forward motion of the aircraft the tone is also different under static and inflight conditions. At low tip relative Mach numbers (less than about 0.85) the significant source of distortion is the intake wall boundary layer. At higher tip Mach numbers the principal distortion under static conditions is the atmospheric turbulence drawn into the intake, but in flight this reduces and other forms of distortion may then dominate.
Energy in East Europe Through 1980
Authors: Strishkov V. V. , Markon G. , Murphy Z. E.
Published: November 2010

Eastern Europe is the world’s largest and most tightly knit multinational economic bloc. It is largest in population although its per capita energy output and industrial production lag considerably behind that of other industrial countries. Originally comprised of eight Soviet satelite states welded together by a common political-economic system patterned after that of the Soviet Union, Eastern Europe now includes Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, and Romania, which are members of the SEV (Soviet Ekonomicheskoy Vzaimopomoshchi, known as Comecon-Council for Mutual Economic Assistance), a highly integrated multinational group. Albania and Yugoslavia, both socialist economies of widely divergent philosophies, are not members of the SEV, although Yugoslavia’s specific status is defined by agreement formalized in 1964. The agreement laid the foundation for Yugoslav participation within the group (it has observer status in half of the Comecon’s 24 Commissions) and cooperation.
Lift and Moment Prediction For an Oscillating Airfoil With a Moving Separation Point
Authors: Perumal P. V. K. , Sisto F.
Published: November 2010

An analytical method for predicting the perturbed aerodynamic reactions of a harmonically oscillating flat plate airfoil with time dependent point of separation is presented. It is shown that this method in conjunction with an empirical knowledge of the time history of the separation point can predict stall-flutter. Numerical results are presented and compared with existing theoretical and experimental results with special emphasis on torsional mode of oscillation.
Gas Turbine Liquid Fuel Treatment and Analysis
Authors: Krulls G. E.
Published: November 2010

A discussion of the gas turbine and its liquid fuel burning experience leads into present concepts and practices. A description is given of the fuel treatment equipment including fuel washing, vanadium inhibition, fuel analysis and system automation. Fuel washing by centrifugal means as well as electrostatic techniques are presented. The effect of fuel parameters on system size, cost and performance is evaluated. A summary of the experience gained shows that fuel treatment has indeed become a practical procedure.
Gas Turbine Flowmeter Measurement of Pulsating Flow
Authors: Lee W. F. Z. , Kirik M. J. , Bonner J. A.
Published: November 2010

A theoretical analysis of a gas turbine flowmeter in the measurement of pulsating flow is presented. The flow considered is periodic with repeatable but arbitrary wave shape. Both fluid drag and nonfluid drag on the rotor system are included in the analysis. Theoretical meter error due to pulsating flow is compared to test results from carefully controlled and instrumented laboratory tests. Results of this comparison and uses of the analysis are discussed.
Comparisons Between Throat and Pipe Wall Tap Nozzles
Authors: Wyler J. S. , Benedict R. P.
Published: November 2010

The history of pipe wall tap nozzles and throat tap nozzles, as to performance characteristics, is briefly reviewed. A series of tests was conducted on pipe wall tap and throat tap nozzle installations at three independent calibration laboratories. These results are presented, analyzed, and compared with existing rational, empirical, and nominal performance characteristics in the form of discharge coefficient versus the throat Reynolds number. On the basis of these results, a recommendation is made that both pipe wall tap and throat tap nozzle installations be considered as equally accurate for use in precision fluid metering work.
Emission Results From Coal Gas Burning in Gas Turbine Combustors
Authors: Pillsbury P. W. , Cleary E. N. G. , Singh P. P. , Chamberlin R. M.
Published: November 2010

As part of a continuing experimental development program supported by the U. S. Office of Coal Research, to prepare the gas turbine portion of an integrated gasification and power generation plant, emissions from scaled and full size coal gas combustors have been measured. Fuel used was a mixture of carbon monoxide, hydrogen, carbon dioxide, methane; and nitrogen, blended to match low heating value coal gas from an air-blown gasifier. The results of testing in a full scale, high pressure combustor rig are compared with the small scale work with respect to carbon monoxide and nitrogen oxides emissions, and the implications for design discussed.
The Acoustically Excited Flame
Authors: Vermeulen P. J. , Danilowich M. S. , Heydlauff E. P. , Price T. W.
Published: November 2010

A premixed laminar propane-air flame burning at the exit of a nozzle, was acoustically excited upstream by a speaker-driver unit. Detailed acoustic measurements were made to show that sound amplification and attenuation can occur over the measurement frequency range from 50 Hz to 350 Hz. The effect of excitation strength and fuel-air ratio was also investigated. Two acoustic phenomena related by forced vortex hydrodynamic behavior have been identified, and were investigated by means of high speed schlieren photographic measurements. The generation of a one-half harmonic of the fundamental frequency was explored and explained in terms of vortex hydrodynamic behavior. The work contributes to the understanding of the origin of noise from acoustically excited combustors.
Effect of Residual Shaft Bow on Unbalance Response and Balancing of a Single Mass Flexible Rotor—Part II: Balancing
Authors: Nicholas J. C. , Gunter E. J. , Allaire P. E.
Published: November 2010

Three methods of balancing a rotor with a residual shaft bow were presented. Method I balanced the total shaft amplitude to zero at the balance speed. Method II balanced the elastic deflection to zero at the balance speed leaving the residual bow amplitude. Method III balanced the total shaft amplitude to zero at the critical speed without actually operating the rotor at the critical. After balancing by Method I, a large amplitude remained near the critical. Method II balanced the rotor to the residual bow amplitude at all speeds except near the critical where the amplitude is slightly larger than the residual amplitude. The optimum balance resulted from balancing by Method III. In this case, the amplitude was less than or equal to the residual bow amplitude for all speeds except at the critical where the amplitude was zero. Method III required that the critical speed be known prior to balancing. For all three balancing methods, the unbalance influence coefficient must be determined. Two procedures for determining this coefficient were discussed. One was the familiar trial weight influence coefficient method and the other was the direct method which does not require trial weights. Part I of this paper discussed the effect of shaft bow on unbalance response.
Some Future Trends in Aero Engine Design for Subsonic Transport Aircraft
Authors: Jackson A. J. B.
Published: November 2010

The current situation of fuel supply, fuel price, noise, and other environmental regulations are reviewed. Some current trends in aero engine design for subsonic transport aircraft are considered and their possible impact on fuel economy, airline economics and the environment are assessed.
Application of CAD/CAM in Forging Turbine and Compressor Blades
Authors: Akgerman N. , Altan T.
Published: November 2010

The design and manufacturing of dies for forging of turbine and compressor blades represent excellent applications for CAD/CAM. Computer programs have been developed to predict the load, the optimum die design, the best preform position before forging, and the minimum stock volume necessary to fill the die cavity. The predicted forging loads and forging positions agreed well with practical values. For numerical-control machining of forging dies, or of electrodes for Electro Discharge Machining (EDM) of the dies, special-purpose programs have been developed. Thus, the necessary fundamentals are available for an integrated CAD/CAM approach in forging of blades for turbine and compressor applications.
Generalized Flow Across an Abrupt Enlargement
Authors: Benedict R. P. , Wyler J. S. , Dudek J. A. , Gleed A. R.
Published: November 2010

Generalized solutions are developed for the flow across an abrupt enlargement. Three cases are considered, namely; an incompressible fluid, a subsonic compressible fluid, and a compressible fluid in supercritical flow. All characteristic quantities are given in the form of dimensionless numbers which are readily useful such as: the loss in terms of the total pressure ratio across the step, the pressure recovery in terms of the static pressure ratio across the step, and the pressure variation across the face of the step in terms of the throat-to-wall pressure ratio. All theoretical equations are verified by new experimental data, and design curves and tables are given for various area ratios operating at various pressure ratios.
The Additive Nature of Film Cooling From Rows of Holes
Authors: Muska J. F. , Fish R. W. , Suo M.
Published: November 2010

A method of superposition which predicts the cumulative effect of film cooling has been described in the literature by Sellers. This method predicts the magnitude and extent of film cooling downstream of multiple injection stations by accounting for the effectiveness level from each upstream station individually. Sellers compared the method with results from multiple slots and good agreement was demonstrated. Because of the simplicity of the method it was proposed as a method to predict the cumulative effect of film cooling from rows of holes. To substantiate this, experiments were conducted with film cooling schemes on flat plates and airfoils. The results of these experiments demonstrate that the method is satisfactory for design of film cooled airfoils in the required range of geometries and coolant flows.
Evaluation of Proposed ASME Performance Test Code 36 for Sound Power Level Determination of Large Steam Turbine-Generators
Authors: Grabkowski S. E. , MacDonald J. , VanSchaick T. E.
Published: November 2010

The “two-surface” correction technique, as it is outlined in ASME Performance Test Code No. 36, is utilized in the determination of large steam turbine-generator sound power level (PWL). Test data obtained from using this method and other PWL calculation methods are presented. The two-surface method did not yield consistent results in the indoor environments encountered and had only limited application in turbine-generator PWL calculations. A modified two-surface approach was also tested. This method, which treats each component as a separate source and uses grids located close to the machine, was found to produce more accurate and confident results.
Some Measured Temperature Characteristics in a Two-Dimensional Heated Jet of Air
Authors: Jenkins P. E.
Published: November 2010

The mean and conditional temperature and velocity profiles and their correlations were measured in a heated jet of air. The conditional measurements were “zone” averaged measurements, taken only in the fully turbulent region of the flow field by using an electronic sampling technique. The zone averaged measurements were taken of the velocity, temperature, shear stress, and the velocity-temperature correlation at three axial stations: x/D = 35, 45, and 50. The jet Reynolds number (based on the jet slot width) was held constant at 1.43 × 104, with a jet exit temperature excess of θ = 35°C. The conditioned profiles show a large variation from the mean measurements in the fully turbulent region of the jet. The zone averaged measurements approach the mean only as the jet center line and jet interface is approached.
High-Temperature Corrosion in Gas Turbines and Steam Boilers by Fuel Impurities—Part VII: Evaluation of Magnesium-Aluminum-Silicon Combinations as Corrosion Inhibitors
Authors: May W. R. , Zetlmeisl M. J. , Annand R. R.
Published: November 2010

Aluminum, alone and in several combinations with magnesium and silicon, has been evaluated as a corrosion inhibitor and slag modifier for heavy fuel ash. Stepwise linear regression analyses were carried out on the data and the results are compared with earlier data on magnesium and silicon. The Mg-Al-Si combination gives superior tolerance to aggravation of corrosion caused by sodium. It gives the slag a friability equivalent to Mg-Si combinations.
Status Report on Closed-Cycle Power Plants in the Federal Republic of Germany
Authors: Bammert K. , Groschup G.
Published: November 2010

In recent years the constructors as well as the users of municipal and industrial power plants have shown a rising interest in the closed-cycle gas turbine. Because of its ability to deliver a large amount of heat without restrictions to the electric power generation, the closed-cycle gas turbine is most favorably qualified for central district heating of large residential quarters. In this paper these aspects of the closed-cycle will be illustrated in the frame of five closed air turbine plants, being in operation in the FRG. The layout of and the operation experience gained with these plants will be discussed. These municipal and industrial power plants are fueled by coal, oil, gas, or even mixtures of these. The special items in the layout of the heaters with respect to the different fuels are shown; the perspectives for further design are discussed.