bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual Energy Use Systems for Industrial, Commercial, and Building Applications
Authors: Biancardi F. R. , Melikian G. , Sgamboti C. T.
Published: April 2015

Integrated dual energy use systems, optimized to provide both electrical (or mechanical) and thermal energy for industrial process heating/cooling or for commercial and residential space conditioning needs, are energy efficient and economic alternatives to conventional single-purpose energy systems. Numerous prime movers, including diesels, gas engines, steam and gas turbines, combined cycles, and other advanced conversion systems, together with an array of different primary energy sources such as gas, oil, coal, biomass and municipal solid waste fuels and thermal storage and control strategies, can result in a complex variety of system configurations. The United Technologies Research Center (UTRC), working with the U.S. Department of Energy, the Electric Power Research Institute, and state and local governments, has developed methodologies and procedures to screen, evaluate, and select optimum dual energy use systems (DEUS) for industrial parks, commercial developments and residential applications or combinations thereof. This paper describes methodologies developed and provides examples of the dual use energy systems defined for use in: (1) single industries, (2) multiple-industry industrial parks, (3) recovery of waste heat from a nuclear fuel processing facility, and (4) burning of solid and municipal waste sources. In addition, specific sites are described which include residential, commercial and industrial developments being implemented in the Eastern and Western sections of the United States.
Experimental Investigation of Dynamic Distortion Properties in Transonic Flow Diffuser
Authors: Xijun Huang , Huaiti Li , Jinzhong Dong
Published: April 2015

This paper provides a description of experimental studies of various dynamic distortion properties in a two-dimensional transonic diffuser. Based upon the measured dynamic pressure across the diffuser discharge section, the Δ PRMS, amplitude power density and probability density function have been analyzed. The results indicate that the dynamic distortion is closely related to the terminal shock wave stability of transonic diffuser, and the distribution of Δ PRMS and PSD are important Properties for dynamic distortion.
Propeller Design Point Calculation Method for Comparing Turbofan/Propfan Engine Performance
Authors: Schmidt Marvin F.
Published: April 2015

This paper presents a method to calculate the design point performance of both single rotation and dual contra-rotation propellers. Major propeller variables such as, power loading (shaft horsepower/prop diameter2), propeller efficiency (Prop Thrust × Acft Veloc/shaft horsepower), propeller tip speed and propeller adiabatic compression efficiency are accounted for and correlated. The resulting propeller performance is then combined with given shaft power producer (engine) performance to yield propfan engine performance. The performance trades between power loading, propeller efficiency, propeller tip speed and propeller adiabatic compression efficiency are presented. Resulting performance, with a given engine, are presented in the form of Figs 7 and 8 for both single and dual contra-rotation propellers. These engine performances can then be compared to advanced turbofan engines that utilize identical technology shaft power producer engines.
Aerodynamic Research on Straight Wall Annular Diffuser for Turbofan Augmentor
Authors: Xie Q. M. , Gu J. G.
Published: April 2015

The effect of non-uniform inlet velocity and temperature profile on the aerodynamic performance of straight wall annular diffuser for turbofan augmentor has been investigated.

The distribution of static pressure, stagnation pressure and temperature has been measured, thus pressure recovery coefficient, velocity profile and temperature profile at different axial station along the diffuser center line can be determined.

The experimental results showed that the momentum ratio ρ¯eV¯e2/ρ¯iV¯i2 of two streams across the diffuser inlet flow splitter is the non-dimensional flow parameter controlling diffuser aerodynamic performance. Thus, it is possible to simulate turbofan augmentor annular diffuser perfomance by using low temperature air flow aerodynamic test under the condition that the diffusers are of similar geometry, have the same inlet velocity profile and maintain the momentum ratio constant.

A correlation for the velocity distribution in the diffuser was also obtained.
Investigation of Transient Technique for Turbine Vane Heat Transfer Using a Shock Tube
Authors: Elrod William C. , Gochenaur John E. , Hitchcock James E. , Rivir Richard B.
Published: April 2015

An investigation was made of a transient technique for determining heat transfer and flow conditions in a cascade of turbine vanes. A shock tube was used to establish, behind a reflected shock, temperature ratios between the gas the vanes simulating the severe operating conditions of modern gas turbines. Heat transfer and flow conditions at five locations (leading edge and 1/4 and 1/2 chord positions on suction and pressure surfaces) were determined by a heat flux gage and by flow visualization with a Mach-Zehnder interferometer. The heat flux gage was a thin-film semiconductor type thermocouple used to measure the surface temperature of a semi-infinite solid as a function of time. Then a transient analysis using a finite difference scheme was used to calculate the heat transfer. The validity of the transient technique was established by measurements with the thin-film gage mounted on the shock tube wall. Analytical results for steady, turbulent heat transfer to a flat plate are somewhat less than the measured results, the difference decreasing with increased shock strength. Analysis of the transient flow conditions in the shock tube provides an explanation of this behavior. The heat transfer conditions for the turbine vane are believed to be established rapidly enough to represent valid steady state measurements for the simulated turbine vane flow conditions.
Large Heavy-Duty Gas Turbines for Base-Load Power Generation and Heat Cogeneration
Authors: Joyce John S.
Published: April 2015

The predominant role of large gas turbines has shifted from peaking-load duty to midrange and base-load electric power generation, especially within combined-cycle plants. Such applications require heavy-duty industrial gas turbines to ensure the same high reliability and availability for continuous service as the associated steam turbines. It is also important that the gas turbines be designed for low maintenance to minimize the necessary outage times and costs for component repair and replacement. The basic design principles and applications of Model V94 gas turbines are discussed with special reference to highly reliable and economic bulk power generation.
Investigation and Experiment on a Short Dump-Diffuser of the Combustor
Authors: Xiao-Chun Hou , Tong-Fu Siao , Jian-Ping Zhong
Published: April 2015

This paper is intended to introduce optimal geometrical parameter matching obtained by using water flow simulation on the box-type specimen and blasting tests on the sector-type specimen for the short dump-diffuser of an annular combustion chamber, and some special problems occurring in practice, such as, the effects of the factors — the head of flame tube, inlet cap, inlet support strut, splitting flow cone, air drawn from the wall surface and inlet velocity profiles on diffuser performance and its flow status, the obtained results provide the foundation for its practical application.
Investigation and Experiment on Optimizing Angles of Variable Stator of Axial Flow Compressor
Authors: Lihua Wu , Fusheng Huang , Feng Liu , Yanli Wang
Published: April 2015

This paper presents the calculation of optimal restagger and test method for ten-stage subsonic axial flow compressor with four rows of variable stator. The test results show that both are in close agreement.

The test results show that the overall compressor performance with optimal restaggers was significantly improved in comparison with the original. The efficiency at mid-speed increased by 12.7%. Surge margin reaches 31.2%. The total range of operation for compressor was expanded by 34%.
Growth of Secondary Flow Losses Downstream of a Turbine Blade Cascade
Authors: Chen L. D. , Dixon S. L.
Published: April 2015

End wall total pressure losses downstream of a low-speed turbine cascade have been measured at several planes in order to determine the changes in secondary flow loss coefficients and the growth of the mixing loss with distance downstream. The results obtained are compared with various published secondary flow loss correlations in an attempt to explain some of the anomalies which presently exist. The paper includes some new correlations including one for the important gross secondary loss coefficient YSG with loading and aspect ratio parameters as well as the upstream boundary layer parameters.
A Correlation for the Secondary Deviation Angle
Authors: Massardo Aristide , Satta Antonio
Published: April 2015

This paper describes a correlation for the evaluation of the spanwise distribution of the secondary deviation angle. This correlation is made through the use of a theoretical method for the calculation of secondary flow which includes the effects of viscosity.

The correlation considers the influence of the spacing and height of the blade, inlet and outlet flow angles, inlet boundary layers and velocity ratio.

The results are compared with the experimental data of various turbine cascade. The agreement is good for most of the cases.
A Cost-Effective Performance Development of the PT6A-65 Turboprop Compressor
Authors: Yoshinaka Tsukasa , Thue Kenneth S.
Published: April 2015

The largest member of the PT6 turboprop engine family, the PT6A-65, was developed in the early 1980’s and went into production in September 1982. The compressor for this engine consisted of four new axial stages combined with an existing centrifugal stage on a single shaft. This paper gives a brief description of the studies leading up to the choice of the compressor configuration and a more detailed examination of the development of the chosen compressor to the required performance level.

The development of this compressor presented a two-fold technical challenge. Firstly, the limited space in the small compressor gas path did not permit the effective use of conventional total pressure and temperature probes for performance evaluation. Secondly, the short time available for development excluded some attractive corrective measures such as the redesign of some of the axial blade rows because the time required would have jeopardized the meeting of the tight development deadline. The first problem was overcome by a combination of limited wall static pressure measurements and an extensive use of numberical flow analysis codes. This approach proved to be quite cost-effective. The second was solved by the adaptation of an existing fully analytically-designed research axial stage to the first stage position in the axial compressor.
Through-Flow Modeling of Axial Turbomachinery
Authors: Dring Robert P. , Joslyn H. David
Published: April 2015

Through-flow analysis, which is at the heart of the aerodynamic design of turbomachinery, requires as aerodynamic input a row-by-row description of the airfoil loss, deviation, and blockage. Loss and deviation have been investigated extensively in both cascades and rotating rigs as well as in numerous two- and three-dimensional analytical studies. Blockage, however, has received far less attention. As defined herein, blockage is a measure of the departure of the flow field from the condition of axisymmetry which is assumed in the through-flow analysis. The fullspan blockage distributions calculated from measured single-stage rotor wake data were used to provide the input to the through-flow analysis, along with the measured fullspan distributions of loss and deviation. Measured and computed results are compared for the single-stage rotor operating with both thick and thin inlet hub and tip boundary layers. It is demonstrated that both the level and the spanwise and streamwise distributions of blockage have a strong impact on the computed rotor exit flow field.
Performance of Axial Compressor With Non-Uniform Exit Static Pressure
Authors: Kodama Hidekazu
Published: April 2015

An analytic model has been developed to predict the performance of axial compressors with an exit static pressure perturbation. The model uses a two dimensional compressible semi-actuator disc model. This method can be applied to the compressor with known circumferential variation in exit static pressure which is measured or predicted by an analytical method. The analytical results are found to be in good agreement with experiments carried out on two transonic fans.
Optimal Control of Change of State of Aircraft Turbine Engine
Authors: Tzu-Cheng Lee , Yan-Shen Guan
Published: April 2015

The paper presents the application of linear quadratic regulator (LQR) theory to the control of change of state of an aircraft turbine engine from rated to maximum. On the basis of the engine digital simulator, an optimal regulator of change of state is designed. The results of simulation of the optimal control system show that: during transient procese, maximum rotor speed deviation is decreased from 148 rpm to 4.5 rpm, thrust settling time is shortened from 7 seconds to 4 seconds, and transient response of turbine outlet temperature is refined from small overshot to monotonic, as compared with the original hydromechanical control system, thus, the improvement is apparent.
Design Approach for an Optimum Prop-Fan Propulsion System
Authors: Brines Gerald L.
Published: April 2015

The predicted potential performance of the Prop-Fan offers a major improvement in the energy efficiency of future, short-range to medium-range transports. This paper describes the approach taken in designing an optimum Prop-Fan propulsion system. Trade-offs in the configuration(s) and performance are discussed, as are the important aspects of integrating the propeller, gearbox, engine, inlet, exhaust, and nacelle. Realizing the impressive potential fuel savings of the Prop-Fan will require very careful engine/airframe integration. Design options that will be compared are: a single-rotation versus counter-rotation arrangement, a tractor versus pusher installation, and wing versus fuselage mounting. In summary, the performance of turbofan powered and Prop-Fan powered, short-haul transports will be compared in detail by using fuel burn, operating costs, and noise as criteria.
Analysis of Blade Flutter in a Mistuned Rotor
Authors: Xu Jianmin , Song Zhaohong
Published: April 2015

This paper presents an investigation of the blade flutter in a mistuned rotor. For this rotor the model in which multiple degrees of freedom for the whole blade are considered. The work is based on the aeroelastic prediction of flutter in a tuned rotor. The analyses involve not only modes, interblade phase angles and stability of the mistuned rotors, but also mechanism of the bending flutter in both tuned and mistuned rotors. One of the most important conclusions is that the flutter of a single blade in any rotor has behavior both self-excited and forced oscillations. The forced excitation comes from the motion of the adjacent blades.
Monatomic Working Gases vs Air for the Closed Brayton Cycle
Authors: Mason J. L. , Mock E. A. , Caldwell R. T. , Pietsch A.
Published: April 2015

Monatomic gas mixtures have low Prandtl numbers, as low as 0.25 or even lower, compared to about 0.7 for air. In a closed Brayton cycle using a low Prandtl number working gas, the three heat exchangers in the cycle will in general be smaller than in a comparable cycle using air. A system study has been made to compare several promising monatomic gases with air, and to explore the economic incentive to replace air in the closed Brayton cycle with a monatomic gas.
Investigations of the Effect of Annulus Taper on Transonic Turbine Cascade Flow
Authors: Bräunling W. , Lehthaus F.
Published: April 2015

In a test facility for rotating annular cascades with three conical test sections of different taper angles (0°, 30°, 45°), experiments are conducted for two geometrically different turbine cascade configurations, a hub section cascade with high deflection and a tip section cascade with low deflection. The evaluation of time averaged data derived from conventional probe measurements upstream and downstream of the test wheel in the machine-fixed absolute system is based on the assumption of axisymmetric stream surfaces. The cascade characteristics, i.e. mass flow, deflection and losses, for a wide range of inlet flow angles and outlet Mach numbers are provided in the blade-fixed relative system with respect to the influence of annulus taper. Some of the results are compared with simple theoretical calculations. To obtain some informations about the spatial structure of the flow within the cascade passages, surface pressure distributions on the profiles of the rotating test wheels are measured at three different radial blade sections. For some examples those distributions are compared with numerical results on plane cascades of the same sweep and dihedral angles and the same aspect ratios. The computer code used is based on a three-dimensional time-marching finite-volume method solving the Euler equations. Both experimental and numerical results show a fairly good qualitative agreement in the three-dimensional blade surface pressure distributions. This work will be continued with detailed investigations on the spatial flow structure.
Analysis and Estimation for Measurement Errors of the Rotation State Behind Rotors
Authors: Sihong Liu
Published: April 2015

In the measurement of aerodynamic parameters behind rotors, measurement errors may be caused by rotation of rotors. These errors are define as rotation state errors which contain two types of errors: weighted error and response error. In this paper, the equations of rotation state errors are derived by the sweep in tegral of the square wave for the first order system. It provides a clear concept for the measurement errors behind rotors and presents the method and equations for analysing and estimating the rotation state errors.
Convergence of Performance Calculation of Twin Spool Turbojet and Turbofan
Authors: Xingjian Zhu , Xueyu Wang , Qingjin Yan
Published: April 2015

A method of order reduction of multivariate non-linear system to calculate twin spool turbojet and turbofan performance is recommended. With the proper incorporation of other approaches, it can achieve satisfactory results in any flight condition and throttle setting. Compare with the experimentation data, it can models the engine very well.
State of the Art in Aircraft Gas Turbine Technology
Authors: Sampl S. R. , Shank M. E.
Published: April 2015

The new series of turbofan engines use advanced technology features which enhance their attractiveness through reductions in the cost of ownership, noise, and pollution. Improvements in aerodynamics, mechanics, electronics, and materials technology reduce the cost of ownership via such factors as cost, reliability, durability, and operability. Primarily, advanced technology addresses fuel consumption, a parameter with a very large effect on direct operating cost. In addition, these advances do not trade convenience of operation for environmental acceptability. The advanced technology concepts used in the new commercial aircraft turbine engines offer both economic and environmental benefits.
An Investigation of Rotating Stall and Surge of a 10-Stage Subsonic Compressor
Authors: Jinan Xie , Xiaoxu Bai
Published: April 2015

This article covers the analysis and study of the surge characteristic in a full-scale 10-stage subsonic compressor under the condition of performance test. The transient responses which arised after the compressor enters in non-stationary condition range are estimated through an improved nonlinear calculation model. There are two different kinds of response (or transient processe) model: stall pattern and surge pattern. The calculated results coincide with the test very well. When relative turning speed ñ ≤ 0.5, the system transient process is shown in stall pattern; when ñ ≥ 0.6, it is surge pattern. The obtainted calculation result has been drawn as a system transient process locus in the nondimensional flow-pressure rise phase plane. The nondimensional parameters affecting system transient process pattern were analysed and compared with the results made by E.M. Greitzer.
Modelling the Axial-Flow Compressors for Calculating Starting of Turbojet Engines
Authors: De-You Yan
Published: April 2015

This paper provides a method of modelling the axial-flow compressors in the low speed starting regime of an engine from windmilling to idling. A structural formula for the model is established by means of reference (1). A method of step-by-step regression is provided by the author for determining the coefficient matrices of the structural formulae. Excellent agreement was obtained between the computational and experimental results.
Gas Turbine Driven Centrifugal Compressors for Gas Storage and Withdrawal Applications
Authors: Hornberger Horst , Wockenfuss Albrecht , Schmidt Klaus D.
Published: April 2015

The increasing acceptance of natural gas as primary energy in different market segments and the variance in consumption between the seasons require more and more buffer storage capacity, because of contracted constant gas supply quantities.

The surplus gas becoming available during the summer time can be stored and withdrawn during the winter time for covering peak demands.

Based on these facts, the gas distribution companies utilize exploited gas fields for gas storage by drilling additional wells and installing gas compression facilities.

Such a compression duty with a wide range in flow and discharge pressure requires a great flexibility of the compression equipment, including high reliability and availability during operation periods.
Local Heat/Mass Transfer Distribution Around Sharp 180 Degree Turn in MultiPass Rib-Roughened Channels
Authors: Han J. C. , Chandra P. R. , Lau S. C.
Published: April 2015

The detailed heat/mass transfer distributions in and around the sharp 180 degree turn of a three-pass square channel were determined by using the naphthalene sublimation technique. The top, bottom, inner (divider) and outer walls of the test channel were naphthalene plates. For the case of rib-roughened tests, the ribs of square cross section were glued periodically in-line on the top and bottom walls of the naphthalene channel in a required distribution. The rib height-to-hydraulic diameter ratios (e/D) were 0.063 and 0.094, whereas the rib pitch-to-height ratios (P/e) were 10 and 20, respectively. The channel Reynolds numbers varied from 30,000 to 60,000. The results showed that, for both the smooth and the ribbed channels, the Sherwood numbers after the sharp 180 degree turn were higher than that before the sharp 180 degree turn; after the turn the Sherwood numbers of the inner wall were higher than that of the outer wall. The results also indicated that the Sherwood numbers on the top, outer and inner walls of the rib roughened channel were higher than that of the smooth channel.
Evaluation of the Blade-to-Blade Flow From a High Speed Compressor Rotor
Authors: Neuhoff F. , Shreeve R. P. , Fottner L.
Published: April 2015

A 0.28m single stage transonic fan was operated in a rotor only configuration. Overall performance was measured and radial distributions of inlet and outlet velocity were obtained using time-averaging combination temperature-pneumatic probes. The blade-to-blade velocity and pressure distributions were measured using the Dual Probe Digital Sampling technique (involving two commercial semi-conductor probes of simple design). Data were obtained from hub-to-tip at both near-sonic and at supersonic inlet relative Mach numbers. The rotor losses were derived as blade-to-blade distributions and the shock losses were evaluated as components of the total loss at each radius. Based on the limited data obtained near sonic conditions, a combination of the profile loss model of Koch & Smith and shock loss model of Dunker was found to predict the measured radial loss distribution quite well. Preliminary observations of rotor shock oscillations are also reported.
SIC Radial Turbine Rotor Development — Material, Design and Fabrication Influences
Authors: Langer Manfred , Siebels Johann E. , Heinrich Hartmut , Schwetz Karl A.
Published: April 2015

With reference to two batches of rotors, the discussion of component development results shows the problem areas in the fabrication, quality inspection and testing of ceramic radial rotors.

Following the evaluation of the present results, future development work must concentrate on the improvement of

- material quality (microstructure, strength)

- component fabrication, i.e. injection molding - binder removal - sintering

- mechanical finishing

- joining techniques.
Flow Visualization of Secondary Flows in Three Curved Ducts
Authors: Sanz G. M. , Flack R. D.
Published: April 2015

Secondary flows were experimentally examined in three 90° curved ducts with square cross sections and different radii of curvature. Dean numbers were from 1.5 × 104 to 3.6 × 104 and radius ratios of 0.5, 2.3, and 3.0 were used. Streak photography flow measurements were made and general developing secondary flow patterns were studied for three cross sections in each bend: the inlet (0° plane), the midpoint (45° plane), and the outlet (90° plane). At the 0° plane, stress driven secondary flows were found to consist of flow toward the duct corners from the center, balanced by return flow at the side bisectors. This resulted in eight symmetric flow patterns at the inlet. After a rapid transition region, the pressure driven secondary flow patterns were found to be characterized by flow moving toward the outer curved wall at the axial midplane and returning to the inner wall along the duct walls. At the 45° and 90° planes two symmetric flow patterns were observed. Secondary flow velocities in the test elbow with the smallest radius of curvature, where centrifugal forces are greater, were as much as 27% higher than secondary flows in the more gradual turns examined in this study. Also, the pressure driven secondary flows at the exit were higher than the stress driven flows at the inlet by as much as 39%. The elbow with a radius ratio of 0.5 was found to influence the upstream inlet conditions the most and the secondary flow velocities at the inlet were as much as 56% higher than for the larger radii of curvature.
Numerical Computation of Three-Dimensional Rotational Inviscid Subsonic Flows, Using the Decomposition of the Flow Field Into a Potential and a Rotational Part
Authors: Chaviaropoulos P. , Giannakoglou K. , Papailiou K. D.
Published: April 2015

The strongly rotational, three-dimensional, steady, inviscid, subsonic flow field in ducts is calculated using the decomposition of the mass flux vector field into a potential and a rotational part.

The resulting formulation requires the solution of two elliptic equations and a procedure for handling the transport of vorticity. A modified strongly implicit finite difference procedure is used for the solution of the elliptic equations, while the transport equations are handled in their Lagrangean form. In the present work, the algorithm, the boundary conditions and the convergence characteristics of the solution are discussed. Numerical results are presented for a rectangular elbow of 90 degrees of turning.
A Study of the Effect of Deterioration on Compressor Surge Margin in Constant-Speed, Single-Shaft Gas Turbine Engines
Authors: Dundas Robert E.
Published: April 2015

A mathematical model of a constant-speed single-shaft gas turbine was devised using a typical compressor map. Performance calculations were performed at various ambient temperatures based on a standard temperature control system for a number of possible component deterioration modes. The effects on compressor operating line were determined.

It was found that only two modes of deterioration; reduction of compressor flow capacity either through fouling or through erosion and closing of turbine nozzle diaphragms, moved the operating line toward surge. Inlet filter clogging must also be minimized in order to avoid surge because resulting distortion can induce stall and surge.
Three-Dimensional Fluid Flow Phenomena in the Blade End Wall Corner Region
Authors: Hazarika B. K. , Raj R. , Boldman D. R.
Published: April 2015

The three-dimensional flow in the blade end wall corner region was investigated. The techniques used in the investigation included flow visualization, static and total pressure measurements with conventional probes, and mean volocity profile measurements with a single sensor inclined hot-wire probe. Six critical axial stations along the blade chord were chosen for detailed measurements based on the flow visualization results. A large number of data points were obtained very close to the corner walls at each axial location including all the components of the mean velocity. Based on the measurements, three vortices were identified. A horseshoe vortex started near the leading edge. A corner eddy was formed between the horseshoe vortex and the corner. Another vortex was formed at the rear portion of the corner due to the secondary flow of the second kind. The relative size and the rate of spread of the vortices in the streamwise direction are discussed.
A General Computational Method for Simulation and Prediction of Transient Behavior of Gas Turbines
Authors: Schobeiri T.
Published: April 2015

This paper describes a general computational method for predicting the dynamic behavior of gas turbines and their components during transient processes of the most varied kinds. Starting from the conservation laws of fluid and thermodynamics, formulas are derived with which non-stationary processes in the most important components of the gas turbine can be accurately predicted. As an example, the transient behavior of an open-cycle gas turbine with extreme changes in load is calculated. The comparison between the calculations and measurements demonstrates the accuracy and the reliability of the computational method. Although this method has so far been applied only to a broad range of power-generating gas turbines extending from open-cycle turbines to air storage turbines, it is also suitable for the simulation of aircraft gas turbines.
A Method of Aerodynamic Design of Blades in Quasi-Three-Dimensional Calculation of Turbomachine
Authors: Zhengming Wang
Published: April 2015

On the basis of the series expansion method on a selected stream line, the problem, in which the profile thickness is automatically adjusted by computer in aerodynamic design of blades for quasi-three-dimensional calculation, is solved. A special inverse problem is formulated in which the shape of mean stream line and the circumferential thickness distribution of profile are given. Six radial sections of a turbine blade are designed by this method.
Meanline Performance Prediction of Volutes in Centrifugal Compressors
Authors: Weber C. R. , Koronowski M. E.
Published: April 2015

Sources of head loss in compressor volutes are reviewed and new models for tangential velocity dump loss and for exit cone loss are presented for use in meanline performance prediction computer programs. The concept of equivalent sizing parameter, SP, for volutes is also introduced and is shown to be valuable for comparing tangential velocity dump loss models against test data. For SP ≥ 1 the new models for tangential velocity dump loss and exit cone loss show only a slight improvement over old loss models, but for SP<1 the new models are clearly superior.
Experimental Unsteady Shock-Boundary Layer Interaction at Single Blades and in Linear Cascades
Authors: Gallus H. E. , Broichhausen K.-D. , Henne J. M.
Published: April 2015

Self-excited vibrations of transonic blading in turbomachines are partly due to unsteady viscous flow effects and shock-boundary layer interaction. To investigate the unsteady flow, experiments have been performed in a transonic windtunnel at single blades and in a cascade, where the central blade is either mounted elastically or driven by electromagnetic shakers to torsional vibration.

The unsteady flow is measured by a stroboscopic schlieren-method including high-speed movies and a recently developed laser-density gradient-technique. The vibration of the blade is controlled by strain gauges.

The test results reveal:

- severe shock wave and boundary layer oscillations occur with separation alternating between shock-induced and trailing edge separation,

- the unsteadiness of the flow largely depends on Mach- and Reynolds number,

- with pitching vibration of the blade, forced and self-excited shock wave oscillations interfere with each other.
Small Diameter Film Cooling Holes: Wall Convective Heat Transfer
Authors: Andrews G. E. , Alikhanizadeh M. , Asere A. A. , Hussain C. I. , Khoshkbar Azari M. S. , Mkpadi M. C.
Published: April 2015

The wall heat transfer resulting from small diameter holes drilled at 90° through gas turbine combustion chamber and turbine blade walls is considered. Available information is briefly reviewed and shown to generally omit the hole approach surface heat transfer and to relate only to the internal hole heat transfer. Experimental techniques are described for the determination of the overall heat transfer in a metal plate with a large number of coolant holes drilled at 90°. The results are compared with conventional short-tube internal heat transfer measurements and shown to involve much higher heat transfer rates and this mainly resulted from the additional hole approach flow heat transfer.
The Aerodynamic Development of a Highly-Loaded Nozzle Guide Vane
Authors: Baines N. C. , Oldfield M. L. G. , Simons J. P. , Wright J. M.
Published: April 2015

A series of high pressure turbine nozzle guide vanes has been designed for progressively increasing blade loading and reduction in blade solidity without additional loss penalty. Early members of the series achieved this by changes to the suction surface contour, but for the latest design the pressure surface contour was extensively modified to reduce the velocities on this surface substantially. Cascade testing revealed that this vane had a higher loss than its predecessor, and this appears to be largely due to a long region of boundary layer growth on the suction surface and possibly also an unsteady separation. These tests demonstrated the value of a flattened pitot tube held against the blade surface in determining the boundary layer state. By using a pitot probe of only modest frequency response (of order 100 Hz) it was possible to observe significant qualitiative differences in the raw signals from laminar, transitional and turbulent boundary layers, which have previously been observed only with much higher frequency instruments. The test results include a comparison of boundary layer measurements on the same cascade test section in two different high-speed wind tunnels. This comparison suggests that freestream turbulence can have a large effect on boundary layer development and growth.
Measurements of the Turbulent Boundary Layer in the Diffuser Behind an Axial-Compressor
Authors: Pfeil H. , Göing M.
Published: April 2015

The paper presents boundary layer measurements in a diffuser behind a one-stage axial-compressor for the case of nearly axial outlet flow-direction from the blades. According to the results, three-dimensional effects caused by the compressor-blading have a great influence on the character and development of the turbulent boundary layer and must be included in methods to predict the diffuser flow.
Multiaxial Life Prediction System for Turbine Components
Authors: Arvanitis S. T. , Symko Y. B. , Tadros R. N.
Published: April 2015

The objective of this paper is to present a complete 3–D life prediction system which was developed for turbine engine components. It will primarily deal with turbine blades and vanes which are subjected to hostile thermal and combustion environments under load which creates cyclic and/or steady multiaxial stress and strain fields. All of the above factors combined are detrimental to the service life of these components and need very careful consideration at the design stage.

The developed multiaxial system for a mission includes evaluation of transient metal temperatures, corresponding elastic and inelastic strains, creep strains and subsequently creep/fatigue lives. The calculations are performed using the ductility exhaustion method. The maximum principal normal strain ranges used in the life analysis are found by a developed procedure for a multi-axial system. The concept is based on analyzing all of the time steps computed in the mission, in order to develop the maximum principal normal strain range whose direction and magnitude is strictly a function of the component geometry and mission loading. The mission creep is then developed by maximizing a cumulative creep function. Directional consistency is maintained in accumulating creep/fatigue damage with respect to the incurred multiaxial stress and strain fields. Also the most damaging mission modes (creep or fatigue) will be separated. Further development in the model includes the capability of analytically obtaining the fatigue curve for any ratio (R) of minimum to maximum strain using baseline fatigue material properties (R=−1.0). Application of the model to an actual uncooled vane correlates well with test rig development experience.
Effects of Slotted Hub and Casing Treatments on Compressor Endwall Flow Fields
Authors: Johnson M. C. , Greitzer E. M.
Published: April 2015

An experimental investigation was carried out to examine the influence of a rotating slotted hub treatment on a compressor stator passage endwall. Detailed mapping of the three-dimensional unsteady velocity field near the hub was done for a smooth hub and a hub having axial skewed slots. With the smooth wall, the velocity measurements indicate that a large region of blockage occurs near the rear of the blade passage. This blockage is seen to be associated with the hub endwall rather than either the suction surface or the pressure surface of the blade. With axial skewed slots, the blockage is markedly decreased, the stalling flow coefficient is reduced, and the peak pressure rise greatly increased. Due to the axial (rear-to-front) flow in the slots, there is a region of fluid removal (from the endwall) near the rear of the passage and a strong fluid injection, or jet, near the front. The data appear to support the idea that it is primarily the flow removal, and not the jet, which is responsible for the improvement in stall margin found with hub and casing treatment. Furthermore, the data indicate that it is the (dissipation of the) high velocities in the jet that is the prime source of the efficiency reduction associated with this treatment.
A Simple Calculation Method for Ratio of Relative Velocity Within Centrifugal Impeller Channel
Authors: Mizuki Shimpei , Watanabe Ichiro
Published: April 2015

A simple but accurate method of calculating ratio of relative velocities within centrifugal impeller channels is proposed using a one-dimensional flow model, whose major parameters are specific speed, non-dimensional root-mean square radius of the inducer inlet, slip factor, flow coefficient and flow angle at impeller exit. After the non dimensional relative velocity at inducer inlet and that at impeller exit are derived, the ratio of relative velocity at impeller exit to that at inducer inlet is obtained. In addition to this, the ratio is divided into two parts: one ratio for the inducer portion and another ratio for the radial portion of the impeller channel.

The computations are conducted both for adiabatic inviscid flow and for two conditions assumed for viscous flow, in which one used an empirical relationship between the total pressure ratio and the peripheral speed of impeller and the other used experimental values for the total pressure ratio as a funtion of the flow rate. By the present simple method, the non-dimensional relative velocities as well as the ratios of the relative velocities for the inlets and the exits of an inducer and an impeller channel are calculated accurately.
Dynamic Behavior of a Solar Heated Receiver of a Gas Turbine Plant
Authors: Bammert K. , Johanning J.
Published: April 2015

The mainly instationary operation of a solar heated receiver can be simulated with sufficient accuracy only if data about the dynamic behavior are available. For this reason, the dynamic behavior of a solar cavity receiver with parabolic dish collector is investigated. The development of a mathematical simulation considering heat transfer and storage processes is presented and the procedure for a numerical solution is illustrated. The performance of the calculation method is finally demonstrated by simulating the passage of a cloud.
Turbine Erosion Exposed to Particulate Flow
Authors: Hamed A. , Tabakoff W. , Mansour M. L.
Published: April 2015

This work presents the results of a detailed study of blade erosion in a two stage axial flow gas turbine. The computations combine particle-blade impact characteristics, as determined from a three dimensional trajectory analysis with blade material erosion equation, which is obtained from experimental data to predict blade erosion. The results show that the pattern and intensity of blade erosion is dependent on the blade row location and that the first rotor is subject to maximum erosion.
An Aerodynamic Study of a Vortex Controlled Low Emission Gas Turbine Combustor
Authors: Sheng Wu Shou , Adkins R. C. , Fletcher R. S.
Published: April 2015

A detailed experimental study has been made on the aerodynamic characteristics of a combustor with variable air admission. Data from the study was used to design a prototype combustor which will be used to demonstrate the reduction of exhaust gas emissions. Unlike the more usual variable geometry combustors, the division of air into the particular zones of this novel type of combustor can be achieved without the complexities of mechanical adjustment.
Evaluation of Damage Tolerance Requirements Using a Probabilistic-Based Life Approach
Authors: Annis C. G. , Hunter D. T. , Watkins T.
Published: April 2015

This paper presents the results of a study using Pratt & Whitney’s probabilistic-based life analysis system to define the impact of damage tolerance requirements now being written into design specifications. An advanced turbine disk design was considered for several combinations of NDE starting with baseline values representative of actual material and NDE capabilities. Significant conclusions are:

(1) Conventional single-valued descriptions of NDE capability (e.g. 90/95, etc.) are incomplete for comparing competing NDE systems.

(2) The scatter about the mean NDE capability has little influence on system behavior.

These conclusions suggest that more complete descriptions of damage tolerance requirements should be considered. NDE requirements, for example, might be better stated in terms of system performance goals – acceptable failure and removal rates – rather than any specific POD/confidence limit requirement.
The Effect of Reynolds Number and Velocity Distribution on LP Turbine Cascade Performance
Authors: Patterson D. J. , Hoeger M.
Published: April 2015

Because of the laminar boundary-layer’s inability to withstand moderate adverse pressure gradients without separating, profile losses in LP turbines operating at low Reynolds numbers can be high. The choice of design pressure distribution for the blading is thus of great importance.

Three sub-sonic LP turbine nozzle-guide-vane cascade profiles have been tested over a wide range of incidence, Mach number and Reynolds number. The three profiles are of low, medium and high deflection and, as such, display significantly different pressure distributions. The tests include detailed boundary-layer traverses, trailing-edge base-pressure monitoring and oil-flow visualisation.

It is shown that the loss variation with Reynolds number is a function of pressure distribution and that the trailing-edge loss component is dominant at low Reynolds number. The importance of achieving late flow transition — rather than separation — in the suction-surface trailing-edge region is stressed.

The paper concludes by remarking on the advantages and practical implications of each loading design.
Impact of ENSIP on Engine Demonstrator Program
Authors: Farmer T. E.
Published: April 2015

Incorporation of the Turbine Engine Structural Integrity Program (ENSIP) has provided a more organized and disciplined approach to the durability related aspects of the engine demonstrator program. As a result, engine capabilities are more easily related and the number of durability problems is reduced. This is accomplished by increased contractor/customer interface in the design analysis, material characterization and verification testing of the engine programs. The demonstrator program has been affected by the ENSIP requirements, particularly the Damage Tolerance aspects. The design analysis is more complex while the configurations tend to be simpler with fewer notched locations. Materials are developed for improved crack propagation life while component and engine testing is expanded to verify this capability. The ENSIP specification effects increases in analysis, materials development, verification testing and durability.
NDE of Structural Ceramics
Authors: Klima Stanley J. , Vary Alex
Published: April 2015

Radiographic, ultrasonic, scanning laser acoustic microscopy (SLAM), and thermo-acoustic microscopy techniques were used to characterize silicon nitride and silicon carbide modulus-of-rupture test specimens in various stages of fabrication. Conventional and microfocus x-ray techniques were found capable of detecting minute high density inclusions in as-received powders, green compacts, and fully densified specimens. Significant density gradients in sintered bars were observed by radiography, ultrasonic velocity, and SLAM. Ultrasonic attenuation was found sensitive to microstructural variations due to grain and void morphology and distribution. SLAM was also capable of detecting voids, inclusions, and cracks in finished test bars. Consideration is given to the potential for applying thermo-acoustic microscopy techniques to green and densified ceramics. The detection probability statistics and some limitations of radiography and SLAM also are discussed.
A Unique, Rapid Uncertainty Analysis for Turbine Engine Testing
Authors: Boedicker Christopher A.
Published: April 2015

I have developed and implemented a computer subroutine (UNCERT) that greatly simplifies the immense problems associated with most uncertainty analyses. This paper presents an overview of the most fundamental and important concepts in uncertainty analysis, a technique which can be used by a test engineer to estimate the accuracy of measured data and values calculated from measured data. Implementation of these uncertainty concepts in a computer code is also explained. Some of the results of an uncertainty analysis which was accomplished for a turbine engine compressor test are used to illustrate the analysis procedure and results. Finally, the benefits of doing an uncertainty analysis as part of a test are briefly discussed.
Research on High Temperature Combustor for Advanced Reheat Gas Turbine
Authors: Mori K. , Kitajima J. , Kimura T. , Nakamura T.
Published: April 2015

Preliminary studies on the high temperature combustors (combustor outlet temperature = 1670–1770K) for the prototype advanced reheat gas turbine were carried out under the national project of Japan - Moonlight Project. This paper describes an outline of the studies; (i) application of an advanced ceramic thermal barrier coating and ODS superalloy, (ii) development of the advanced double-wall cooling system, (iii) research on the ceramic tile combustor.