bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and Numerical Investigations of the Aerodynamical Effects of Coolant Injection Through the Trailing Edge of a Guide Vane
Authors: Bohn Dieter E. , Becker Volker J. , Behnke Klaus D. , Bonhoff Bernhard F.
Published: February 2015

Effective turbine blade cooling is necessary to enhance the efficiency of gas turbines. Usually the coolant is mainly ejected through the trailing edge of the vanes. In addition to the desired temperature reduction at the trailing edge there is a 3D-aerodynamical interaction between the hot gas and the coolant. The complex mechanisms of the mixture are a main problem in the numerical prediction of the flow situation in this region.

This paper presents the experimental and numerical results of investigations of annular guide vanes. The experiments were conducted in a scaled turbine test rig. The mixing flow of coolant and hot gas was analyzed by measurement of the distribution of both velocity and turbulence very close to the trailing edge using a 2D-LDA measurement technique at different radial positions.

The experimental results show that the radial and circumferential distribution of the coolant depends on the pressure gradient in both directions. Inside of the mixture region the turbulence was found to be anisotropic resulting in a non-symmetrical distribution of the coolant.

For the numerical calculations a Navier-Stokes-Code was used. The numerical scheme works on the basis of an implicit finite volume method combined with a multi block technique. In order to simulate the aerodynamical effects near the injection slot of the vane it was nessessary to include the coolant flow inside the guide vane.
Performance Improvement Through Indexing of Turbine Airfoils: Part 1 — Experimental Investigation
Authors: Huber F. W. , Johnson P. D. , Sharma O. P. , Staubach J. B. , Gaddis S. W.
Published: February 2015

This paper describes the results of a study to determine the performance improvements achievable by circumferentially indexing successive rows of turbine stator airfoils. An experimental / analytical investigation has been completed which indicates significant stage efficiency increases can be attained through application of this airfoil clocking concept. A series of tests was conducted at the National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center (MSFC) to experimentally investigate stator wake clocking effects on the performance of the Space Shuttle Main Engine Alternate Fuel Turbopump Turbine Test Article. Extensive time-accurate Computational Fluid Dynamics (CFD) simulations have been completed for the test configurations. The CFD results provide insight into the performance improvement mechanism.

Part one of this paper describes details of the test facility, rig geometry, instrumentation, and aerodynamic operating parameters. Results of turbine testing at the aerodynamic design point are presented for six circumferential positions of the first stage stator, along with a description of the initial CFD analyses performed for the test article. It should be noted that first vane positions 1 and 6 produced identical first to second vane indexing. Results obtained from off-design testing of the “best” and “worst” stator clocking positions, and testing over a range of Reynolds numbers are also presented.

Part two of this paper describes the numerical simulations performed in support of the experimental test program described in part one. Time-accurate Navier-Stokes flow analyses have been completed for the five different turbine stator positions tested. Details of the computational procedure and results are presented. Analysis results include predictions of instantaneous and time-average mid-span airfoil and turbine performance, as well as gas conditions throughout the flow field. An initial understanding of the turbine performance improvement mechanism is described.
Split Stream Boilers for High Temperature/High Pressure Topping Steam Turbine Combined Cycles
Authors: Rice Ivan G.
Published: February 2015

Research and Development work on high temperature and high pressure (up to 1500 °F TIT and 4500 psia)1 topping steam turbines and associated steam generators for steam power plants as well as combined cycle plants is being carried forward by DOE, EPRI and independent companies. Aero Derivative gas turbines and Heavy Duty gas turbines both will require exhaust gas supplementary firing to achieve high throttle temperatures. This paper presents an analysis and examples of a split stream boiler arrangement for high temperature and high pressure topping steam turbine combined cycles. A portion of the gas turbine exhaust flow is run in parallel with a conventional heat recovery steam generator (HRSG). This side stream is supplementary fired opposed to current practice of full exhaust flow firing. Chemical fuel gas recuperation can be incorporated in the side stream as an option. A significant combined cycle efficiency gain of 2 to 4 percentage points can be realized using this split stream approach. Calculations and graphs show how the DOE goal of 60 % combined cycle efficiency burning natural gas fuel can be exceeded. The boiler concept is equally applicable to the integrated coal gas fuel combined cycle (IGCC).
Transition in a Separation Bubble
Authors: Malkiel E. , Mayle R. E.
Published: February 2015

In the interest of being able to predict separating-reattaching flows, it is necessary to have an accurate model of transition in separation bubbles. An experimental investigation of the process of turbulence development in a separation bubble shows that transition occurs within the separated shear layer. A comparison of simultaneous velocity traces from probes separated in the lateral direction suggests that Kelvin-Helmholtz waves, which originate in the laminar shear layer, do not break down to turbulence simultaneously spanwise when they proceed to agglomerate. The streamwise development of intermittency in this region, can be characterized by turbulent spot theory with a high dimensionless spot production rate. Moreover, the progression of intermittency along the centerline of the shear layer is similar to that in attached boundary layer transition. The transverse development of intermittency is also remarkably similar to that in attached boundary layers.

The parameters obtained from these measurements agree with correlations which were previously deduced from turbulence intensity measurements.
3D Unsteady Flow and Forces in Centrifugal Impellers With Circumferential Distortion of the Outlet Static Pressure
Authors: Fatsis Antonios , Pierret Stephane , Van den Braembussche René
Published: February 2015

This paper describes the numerical investigation of the centrifugal impeller response to downstream static pressure distortions imposed by volutes at off-design operations. An unsteady 3D Euler solver with non-reflecting upstream and downstream boundary conditions and phase-lagged periodicity conditions is used for this purpose.

The mechanisms governing the unsteady flow field are analysed. A parametric study shows the influence of the acoustic Strouhal number on the amplitude of the flow perturbations. Radial forces calculated on backward leaned and radial ending centrifugal impellers, show non-negligible influence of the impeller geometry.
Effect of Modification to Tongue and Impeller Geometry on Unsteady Flow, Pressure Fluctuations and Noise in a Centrifugal Pump
Authors: Dong R. , Chu S. , Katz J.
Published: February 2015

Particle Image Velocimetry (PIV), pressure and noise measurements are used to study the effect of modifications to tongue and impeller geometries on the flow structure and resulting noise in a centrifugal pump. It is demonstrated that the primary sources of noise are associated with interactions of the non-uniform outflux from the impeller (jet/wake phenomenon) with the tongue. Consequently, significant reduction of noise is achieved by increasing the gap between the tongue and the impeller up to about 20% of the impeller radius. Further increase in the gap affects the performance adversely with minimal impact on the noise level. When the gap is narrow, the primary sources of noise are impingement of the wake on the tip of the tongue, and tongue oscillations when the pressure difference across it is high. At about 20% gap, the entire wake and its associated vorticity trains miss the tongue, and the only (quite weak) effect of nonuniform outflux is the impingement of the jet on the tongue. An attempt is also made to reduce the non-uniformity in outflux from the impeller by inserting short vanes between the blades. They cause reduction in the size of the original wakes, but generate an additional jet/wake phenomenon of their own. Both wakes are weak to a level that their impacts on local pressure fluctuations and noise are insignificant. The only remaining major contributor to noise is tongue oscillations. This effect is shown to be dependent on the stiffness of the tongue.
Test Results of a New Damper Seal for Vibration Reduction in Turbomachinery
Authors: Vance John M. , Li Jiming
Published: February 2015

A new type of labyrinth gas seal for damping vibration and whirl, called the TAMSEAL, has been evaluated in both non-rotating and rotating tests at Texas A&M University. Test results of the prototype, along with comparison tests of a conventional labyrinth seal, show up to one hundred times more direct damping than the conventional bladed seal. The new design also has a feature that blocks swirl of the working fluid, which is known to be rotordynamically destabilizing in machines with conventional seals. Coastdown tests of the new seal were conducted at various pressures on a rotordynamic test apparatus with a critical speed at 4000 rpm and compared with identical testing of a conventional labyrinth seal. Rap tests of both seals were also conducted to measure the logarithmic decrement of free vibration, and the leakage of both seals was measured. Test results show large reductions in peak vibration at the critical speed in all cases, with the critical speed being completely eliminated by the TAMSEAL at some pressure drop conditions. The leakage rate of the tested TAMSEAL is higher than the conventional seal at the same clearance, but the large reductions in vibration and whirl amplitudes suggest that the TAMSEAL could be operated with smaller clearances than conventional labyrinth seals.
Applications of Accurate Isentropic Exponent Determination for Fuel Gas Measurement
Authors: Pack David J. , Edwards Terry J. , Fawcett Derek
Published: February 2015

This paper discusses the determination and application of the isentropic exponent to the various thermodynamic processes found in a high pressure natural gas transmission system.

Increasing demands for more precise measurement of natural gas, coupled with the need for greater efficiency and accountability of transportation and processing operations had led to our research and development efforts into the more precise measurement of gas flow, and the determination of gas thermodynamic properties including isentropic exponent.

The isentropic exponent has many applications, some of which include:

• the determination of the expansion factor ϵ, for calcuation of flow using an orifice or venturi type meter;

• the volumetric efficiency in a reciprocating compressor;

• the determination of the compression head for a centrigual compressor;

• the engine power required for the set given conditions for gas compressor;

• the calculation of discharge temperatures for compressors; and

• the direct measurement of gas density.

As can be appreciated, the application of an incorrect value for the isentropic exponent represents an error in the parameter determined. For large volume gas flows, this can translate into a significant cost penalty.
Flow Characteristics and Aerodynamic Losses of Film-Cooling Jets With Compound Angle Orientations
Authors: Lee Sang Woo , Kim Yong Beom , Lee Joon Sik
Published: February 2015

Oil-film flow visualizations and three-dimensional flow measurements using a five-hole probe have been conducted to investigate the flow characteristics and aerodynamic loss distributions of film-cooling jets with compound angle orientations. For a fixed inclination angle of the injection hole, measurements are performed at various orientation angles to the direction of the mainstream in the case of three velocity ratios of 0.5, 1.0 and 2.0. Flow visualizations for the velocity ratio of 2.0 show that the increase in the orientation angle furnishes better film coverage on the test surface, but gives rise to large flow disturbances in the mainstream. A near-wall flow model has been proposed based on the surface flow visualizations. It has also been found from the flow measurements that as the orientation angle increases, a pair of counter-rotating vortices turn to a single strong one, and the aerodynamic loss field is closely related to the secondary flow. Even in the case of the velocity ratio of 2.0, aerodynamic loss is produced within the jet region when the orientation angle is large. Regardless of the velocity ratio, the mass-averaged aerodynamic loss increases with increasing orientation angle, the effect of which on aerodynamic loss is pronounced when the velocity ratio is large.
Heat Transfer Augmentation in a Rectangular Channel With Slit Rib-Turbulators on Two Opposite Walls
Authors: Hwang Jenn-Jiang , Liou Tong-Miin
Published: February 2015

The effect of slit ribs on heat transfer and friction in a rectangular channel is investigated experimentally. The slit ribs are arranged in-line on two opposite walls of the channel. Three rib open-area ratios (β=24%, 37%, and 46%), three rib pitch-to-height ratios (Pi/H=10, 20, and 30), and two rib height-to-channel hydraulic diameter ratios (H/De=0.081, and 0.162) are examined. The Reynolds number ranges from 10000 to 50000. Laser holographic interferometry is employed to quantitatively measure the local heat transfer coefficients of the ribbed wall, and qualitatively observe the flow over the ribbed wall. The results show that the slit rib has an advantage of avoiding “hot-spots”. In addition, the heat transfer performance of the slit-ribbed channel is much better than that of the solid-ribbed channel. Semi-empirical correlations for friction and heat transfer are developed to account for rib spacings and open-area ratios. These correlations may be used in the design of turbine blade cooling passages.
The Effect of Twisted Tape Width on Heat Transfer and Pressure Drop for Fully Developed Laminar Flow
Authors: Chakroun Walid M. , Al-Fahed Sami F.
Published: February 2015

A series of experiments was conducted to study the effect of twisted-tape width on the heat transfer and pressure drop with laminar flow in tubes. Data for three twisted-tape wave lengths each with five different widths have been collected with constant wall temperature boundary condition. Correlations for the friction factor and Nusselt number are also available. The correlations predict the experimental data to within 10 % to 15 % for the heat transfer and friction factor, respectively. The presence of the twisted tape has caused the friction factor to increase by a factor of 3 to 7 depending on Reynolds number and the twisted-tape geometry. Heat-transfer results have shown an increase of 1.5 to 3 times that of plain tubes depending on the flow conditions and the twisted-tape geometry. The width shows no effect on friction factor and heat transfer in the low range of Reynolds number but have a more pronounced effect on heat transfer at the higher range of Reynolds number. It is recommended to use a loose-fit tapes for low Reynolds number flows instead of tight-fit in the design of heat exchangers because they are easier to install and remove for cleaning purposes.
Effects of Free Stream Turbulence on the Instantaneous Heat Transfer in a Wall Jet Flow
Authors: Yavuzkurt Savash
Published: February 2015

This is a preliminary study in order to understand how free stream turbulence increases the heat transfer. Effects of free stream turbulence on the instantaneous heat transfer were investigated in a wall jet flow. Heat transfer traces obtained by a hot film probe flush-mounted with the surface showed an intermittent structure with definite peaks at certain time intervals. Number of peaks per unit time increased with increasing turbulence intensity.

A wall jet test rig was designed and built. The initial thickness and the velocity of the wall jet were 10 cm and 24.4 m/s respectively. The hot film probe which was flush with the surfaces was positioned at 10 cm intervals on the surface in the flow direction. The profiles of mean velocity and axial component of the Reynolds stress were measured with a horizontal hot wire probe. Space correlation coefficients for u′ and q′ were obtained in the vertical direction to the wall.

This paper concentrates on the effects of turbulence level on the instantaneous heat transfer at the wall. It is speculated that intermittent structure of the heat transfer traces are related to burst phenomena and increase in heat transfer is due to increased ejections (bursts) at the wall with increasing turbulence levels.
Bulk Flow Pulsations and Film Cooling: Flow Structure Just Downstream of the Holes
Authors: Ligrani Phillip M. , Cuthrell J. Michael , Gong Ruoming
Published: February 2015

Experimental results are presented which describe the effects of bulk flow pulsations on film cooling from a single row of simple angle film cooling holes. The pulsations are in the form of sinusoidal variations of static pressure and streamwise velocity. Such pulsations are important in turbine studies because: (i) static pressure pulsations result in significant periodic variations of film cooling flow rates, coverage, and trajectories, and (ii) static pressure pulsations occur near blade surfaces in operating engines from potential flow interactions between moving blade rows and from families of passing shock waves. Distributions of ensemble-averaged and time-averaged Reynolds stress tensor components are investigated at x / d=4.5 along with distributions of all three mean velocity components, where x is streamwise distance from the downstream edge of the holes and d is hole diameter. Important changes are evident in all measured quantities which must be accounted for in any closure model used to simulate unsteadiness from the relative motion of two adjacent blade rows. In particular, maximum Reynolds shear stresses −2u′v′¯/u∞¯2 are lower in regions containing the largest film concentrations because the strong shear layer produced by the injectant is more three-dimensional, larger in extent, and oscillates its position from the wall with time. The pulsations also produce significant changes to profiles of u′w′¯/u∞¯2, u′2¯/u∞¯2, v′2¯/u∞¯2, and w′2¯/u∞¯2 in the film cooled boundary layer, and increase u¯/u∞¯ over most of the boundary layer thickness at spanwise locations near the holes.
Surface Fouling in Aviation Fuels: An Isothermal Chemical Study
Authors: Jones E. Grant , Balster Walter J. , Pickard James M.
Published: February 2015

Surface fouling in aircraft fuel lines that results from autoxidation of aviation fuel remains a serious and very complicated problem. This area has been studied using two Jet-A fuels, POSF-2827 and POSF-2980. The results of a series of dynamic experiments conducted in a single-pass, tubular heat exchanger operated at very slow flow rates under near-isothermal conditions are reported herein. Such studies, by minimizing complications resulting from fluid dynamics and heat flow, constitute a simpler global approach to the chemistry of fouling. The basis for the selection of experimental test conditions is discussed, and data from measurements of dissolved oxygen and surface deposition as a function of fuel stress duration are presented. The effects of parameters such as reaction temperature, tube diameter, experimental test time, and fuel dopants are considered.
Monitoring Combustion Turbine Performance in the Electric Utility Industry
Authors: Baldwin Richard M. , Smalley Anthony J. , Terrell James E. , Prince Robert , Gray Charles N. , Eskin Leo D. , Quentin George H.
Published: February 2015

This paper describes a monitoring and diagnostic system implemented on four Westinghouse 501 B4 peaking combustion turbines at the Tennessee Valley Authority’s (TVA’s) Gallatin Combustion Turbine Site, near Nashville, Tennessee. As a follow-up to a maintenance upgrade on the turbine trains, a means was sought to maximize service reliability and minimize labor and maintenance. The system consists of a vibration data acquisition system, ports to access control system data, a local area network, and software to diagnose vibration and performance problems. The analysis software modules expand the state-of-the-art by automated extraction of high level information from sampled raw data and they provide recommendations in graphical, tabular, and interactive formats. The software algorithms are designed to reduce required user expertise and input, and to enhance guidance to operators for appropriate action.
Reheat and Regenerative Gas Turbines for Feed Water Repowering of Steam Power Plant
Authors: Negri di Montenegro G. , Gambini M. , Peretto A.
Published: February 2015

This study is concerned with the repowering of existing steam power plants (SPP) by gas turbine (GT) units. The energy integration between SPP and GT is analyzed taking into particular account the employment of simple and complex cycle gas turbines. With regard to this, three different gas turbine has been considered: simple Brayton cycle, regenerative cycle and reheat cycle. Each of these cycles has been considered for feed water repowering of three different existing steam power plants. Moreover, the energy integration between the above plants has been analyzed taking into account three different assumptions for the SPP off-design conditions. In particular it has been established to keep the nominal value for steam turbine power output or for steam flow-rate at the steam turbine inlet or, finally, for steam flow-rate in the condenser.

The numerical analysis has been carried out by the employment of numerical models regarding SPP and GT, developed by the authors. These models have been here properly connected to evaluate the performance of the repowered plants.

The results of the investigation have revealed the interest of considering the use of complex cycle gas turbines, especially reheat cycles, for the feed water repowering of steam power plants. It should be taken into account that these energy advantages are determined by a repowering solution, i.e. feed water repowering which, although it is attractive for its simplicity, do not generally allows, with Brayton cycle, a better exploitation of the energy system integration in comparison with other repowering solutions. Besides these energy considerations, an analysis on the effects induced by repowering in the working parameters of existing components is also explained.
Experimental Study on Convective Heat Transfer of Radial Air Flow in Rotating Multi-Channels
Authors: Hwang G. J. , Kuo C. R. , Chang C. Y.
Published: February 2015

Experimental study on the convective heat transfer of radial air flow in rotating multi-channels was performed. Three sets of test sections, one single-flow passage, one nine-flow passages and one twenty-five-flow passages with the same cross sectional area of 9π mm2, were applied to the experiments. The test section was formed by rectangular blocks of aluminum alloy with circular flow passages. Between two adjacent blocks, a Bakelite board of 1 mm thickness was placed to separate axial wall heat conduction for local heat transfer measurement. The parameters involved are the Reynolds number Re, the Rotation number Ro, the Buoyancy parameter Gr/Re2, and the ratio of the heat transfer area Ap/Ac. The heat transfer results of radially rotating circular ducts based on per-passage and per-system were obtained.
Identification of Mechanical Alterations From Their Effect on Performance of a Radial Compressor
Authors: Mathioudakis K. , Tsalavoutas A.
Published: February 2015

An experimental study of the influence of mechanical alterations in a stage of a radial compressor with a vaned diffuser is presented. The mechanical alterations considered correspond to changes which can be produced by the occurrence of faults or deterioration of the compressor. They include the insertion of an inlet obstruction, an obstruction in a diffuser passage, increase of impeller tip clearance, and impeller fouling.

The change in the compressor performance parameters, from the reference condition, is established from the experimental results. These changes are referred to the overall stage performance but also to its components, impeller, and diffuser. In order to establish diagnostic abilities, appropriate indices are introduced. The behaviour of these indices is related to the altered stage conditions and the possibility of using them for identifying the stage condition is demonstrated.
Achieving Improved Cycle Efficiency via Pressure Gain Combustors
Authors: Gemmen Randall S. , Janus Michael C. , Richards George A. , Norton Thomas S. , Rogers William A.
Published: February 2015

As part of the Department of Energy’s Advanced Gas Turbine Systems Program, an investigation is being performed to evaluate “pressure gain” combustion systems for gas turbine applications. This paper presents experimental pressure gain and pollutant emission data from such combustion systems. Numerical predictions for certain combustor geometries are also presented. We report that for suitable aerovalved pulse combustor geometries studied experimentally, an overall combustor pressure gain of nearly 1 percent can be achieved. We also show that for one combustion system operating under typical gas turbine conditions, NOx and CO emissions, are about 30 ppmv and 8 ppmv, respectively.
Characteristic Time Modeling of NOx Emissions and Combustion Efficiency for a Staged Combustion Ramjet
Authors: Rich John T. , Mellor Arthur M.
Published: February 2015

The semi–empirical characteristic time model (CTM), in which algebraic equations based on first principles have been validated, primarily for turbine engines, for the correlation of combustor behavior (NOx and CO emissions, combustion efficiency, lean blowoff, and lean lightoff) is examined for its applicability to staged combustion ramjets. The CTM was chosen as some success has been observed in collapsing data from different turbine combustors and in predicting performance for other configurations using a single set of model constants. Its independent parameters are times characteristic of turbulent mixing, chemistry, and fuel spray evaporation. These times are expressed in terms of combustor geometry, inlet conditions, fuel properties, and injector design.

Tests of the ramjet combustor were conducted at United Technologies Research Center with varying inlet temperature, pressure, equivalence ratio and combustion length, and the predictions are compared with the measurements. First, however, significant model development was conducted because of a number of design differences between the staged combustion concept and the configurations with which the model was originally validated. A method for computing the fraction of total air flow participating in combustion at the various fuel injection locations is postulated. The results obtained in this study are encouraging, particularly for NOx, and suggest additional tests required for staged combustion CTM development.
Extended Duration Thermal Stability Test of Improved Thermal Stability Jet Fuels
Authors: Dieterle Gordon L. , Binns Kenneth E.
Published: February 2015

A single-pass, dual heat exchanger system called the Extended Duration Thermal Stability Test (EDTST) system was developed for evaluating jet fuel thermal stability. Various JP-8 fuels and thermal stability additives have been evaluated in the system. The test results indicate that additives can substantially improve the thermal stability of conventional jet fuels. Relationships of bulk and wetted wall temperatures on coking deposits that form in heated tubes have also been evaluated.

To date, tests conducted with EDTST have verified that additives can improve the thermal stability of JP-8 fuels. The goal of operating at wetted wall temperatures of 260°C (500°F) has been achieved. The goal for bulk fuel temperatures of 218°C (425°F) with no deposits has not been achieved. Additional additive candidates are to be evaluated in the EDTST system to identify additives that meet both the wetted wall and bulk fuel temperature goals of this program. However, if the bulk temperature goal cannot be totally achieved, the JP-8 fuel specification will most probably be changed to take advantage of the wetted wall temperature improvement already demonstrated by a JP-8+100 additive candidate.
Rugged ATS Turbines for Alternate Fuels
Authors: Wenglarz Richard A. , Nirmalan Nirm V. , Daehler Thomas G.
Published: February 2015

A major national effort is directed to developing advanced turbine systems designed for major improvements in efficiency and emissions performance using natural gas fuels. These turbine designs are also to be adaptable for future operation with alternate coal and biomass derived fuels. For several potential alternate fuel applications, available hot gas cleanup technologies will not likely be adequate to protect the turbine flowpath from deposition and corrosion. Consequently, ruggedized versions of ATS turbines will probably be needed. This paper describes ruggedization approaches, particularly to counter the extreme deposition and corrosion effects of the high inlet temperatures of ATS turbines using alternate fuels.
NT164 Silicon Nitride Gas-Turbine Engine Turbine Blade Manufacturing Development
Authors: Bright Eric , Burleson Roger , Dynan Steve A. , Collins William T.
Published: February 2015

Norton Advanced Ceramics (NAC) has performed ceramic turbine blade fabrication development as part of several DOD and DOE-sponsored programs including: (1) The Experimental Turbine Engine Concept (ETEC); (2) The Advanced Turbine Technology Applications Project (ATTAP); (3) The Ceramic Turbine Engine Development Project (CTEDP); and (4) The Ceramic Stationary Gas Turbine (CSGT). NAC has developed two HIPed silicon nitide materials for fabricating turbine blades within these programs — One is designated NT154; and the second is designated NT164. Under the ETEC program with AlliedSignal Engines, NT154 blades were fabricated and delivered for proof and engine testing. Blade fabrication development efforts were augmented by NAC’s work under the ATTAP, which was directed at developing manufacturing technologies for rotors, stators, scrolls, vanes, and other components. Under the ATTAP, complex-shape forming was emphasized utilizing pressure slip-casting. NAC has employed pressure slip casting developed under the ATTAP to fabricate ceramic turbine blades and other gas-turbine components for various advanced heat-engine efforts. NT154 nozzles have been delivered to AlliedSignal Engines under internally sponsored and DOD-sponsored programs. NT154 diffusers, nozzles, and monorotors have been delivered to Sundstrand Power Systems. Under the CTEDP and CSGT programs, continued efforts on turbine blade fabrication development are anticipated for 1995 and beyond. Work under the CTEDP program with AlliedSignal Engines is focused on cost reduction through process simplification and scale-up. Under the CSGT program, NAC is participating with Solar Turbines Incorporated to deliver prototype quantities of NT164 silicon nitride blades using a controlled fabrication process. NAC is utilizing its prior experience in fabricating similar blade geometries under the ETEC, ATTAP, and CTEDP programs in the CSGT effort.
Centrifugal Compressor Stage Preliminary Aerodynamic Design and Component Sizing
Authors: Aungier Ronald H.
Published: February 2015

Procedures are presented for the preliminary aerodynamic design of centrifugal compressor stages. Methods for selecting the key aerodynamic and geometrical design parameters are based on actual stage design experience, supplemented by performance analysis results. Basic component geometry sizing procedures are presented for impellers, vaneless diffusers, vaned diffusers, crossover bends, return channels and volutes. The preliminary stage designs feature well matched components and practical component geometry. The stage geometry is defined in sufficient detail to permit evaluation by a mean streamline performance analysis and to provide the initial geometry for refinement by detailed aerodynamic design procedures. A preliminary stage design can typically be generated in a matter of minutes. Sample designs are evaluated with a performance analysis to demonstrate the close agreement between design objectives and predicted performance.
Aerodynamics of a Centrifugal Compressor Impeller With Transonic Inlet Conditions
Authors: Krain H. , Hoffmann B. , Pak H.
Published: February 2015

Performance and laser measurement results are presented for a transonic centrifugal compressor stage, equipped with a backswept rotor designed for 586 m/s tip speed and a mean relative inlet tip Mach number of 1.30.

The flow field features of the rotor are analysed in detail with the help of laser measurements and the results obtained from a 3D viscous calculation. Both laser measurements and calculations are carried out for the impeller’s design point and a comparison between measured and calculated data is presented for four measurement planes representing the inlet, exit and channel flow conditions. The maximum relative Mach number is found to be 1.45 and a jet/wake type flow exists in the rear part of the flow channel with the wake concentrating in the shroud region. For the operating point investigated, the wake development is due more to the strong shroud curvature in the meridional plane than to a shock induced boundary layer separation. Laser measurements and calculations point to a significant flow displacement in the impeller exit region caused by the wake flow. The theoretical results indicate that a flow separation occurs also at the front side of the vaneless diffuser.
Numerical Investigation of 3D Flow and Torque Transmission in Fluid Couplings Under Unsteady Working Condition
Authors: Formanski T. , Huitenga H. , Mitra N. K. , Fiebig M.
Published: February 2015

Hydrodynamic couplings transmit torque by fluid circulation due to a speed differential between the impeller on the drive side and the runner on the driven side without mechanical contact. Detailed studies of the 3D flow in fluid couplings working at steady operating point were carried out in the last few years for laminar and turbulent flows. In this paper a study of fluid couplings working under unsteady operating conditions is reported for the first time. The unsteady Reynolds averaged Navier-Stokes equations together with the k-ϵ model have been solved by a finite-volume method. The calculations were done by using contour-fitted grids with non-staggered variable arrangement in a rotating frame of reference. The results give insight into the flow structure inside a coupling under unsteady working condition. An integration of the flow field for the considered operating points yields the transmitted torque. The time history of the change of the moment of momentum gives further insights into the behaviour of a fluid coupling under unsteady operating conditions.
Experimental and Computational Study of a Radial Compressor Inlet
Authors: Koch Jay M. , Chow Peter N. , Hutchinson Brad R. , Elias Steve R.
Published: February 2015

Flow field measurements and flow visualization for a quarter scale model of a radial compressor inlet are presented for varying flow rates and inlet profiles. Non-uniform inlet profiles are created using a 90° bend directly upstream of the inlet. Experimental results are compared with the CFD analysis from a commercial 3-D Navier Stokes code. The experimental and computational results show good agreement, even in regions of reverse flow. The results from this study show CFD analysis can be used with confidence to predict the performance of radial compressor inlets.
Experimental Investigation in Annular Compressor Cascades at Transonic Flow Conditions
Authors: Schulz K. , Dalbert P. , Bölcs A.
Published: February 2015

The paper describes flow measurements in an annular compressor cascade at sub- and supersonic inlet flow conditions. The investigation is concentrated on the evolution of the flow field along the blade passage.

A homogeneous flow could be realized in the test section at midspan with carefully directed suction by a splitter downstream of the blade passage.

Two typical compressor cascades (Multiple circular arc profile (MCA) and controlled diffusion (C.D.)) have been investigated at similar inlet flow conditions in the whole operating range with a maximum relative inlet Mach number of about 1.3.

Detailed flow measurements have been performed over several axial and radial positions along the whole blade passage. The velocity vectors have been measured with a Laser-2-Focus anemometer and the total pressure with miniature pilot-probes. Cascade overall performance, blade-surface-pressure-distributions and flow-visualization are presented.

The obtained results show that the blade shape has a strong influence on the loss behavior especially at off design conditions and on the shock system influencing the whole flow field of the blade row. Different boundary layer evolution on the suction side (measured with Laser-2-Focus) causes the shock to be fixed or in fluctuation resulting in different losses (shock-, profile-, overall losses).
A Station Engineering Electrical/Controls Construction Database
Authors: Thébeau Michèle A.
Published: February 2015

This paper will discuss the structure, features and capabilities of the Union Gas Ltd. Station Engineering Electrical/Controls Construction Database.

The central feature of the application is the R:BASE database. In general, the database contains information which pertains to a transmission, measurement, regulating and/or compressor station. From the menu-driven custom application software used with R:BASE, the user can perform mass data manipulation to maintain the database, as well as create reports such as the equipment catalogue report. Finally, data can be extracted from the database to auto-generate junction box termination schedules as well as auto-generate, through a CAD software package, instrumentation loop drawings. These have the ability to show information such as panel and I/O module terminations, junction/termination box schedules, cable and conduit schedules, and device information such as alarm, shutdown and control setpoints.
Isolation of Major Noise Sources on Natural Gas Turbomachinery Packages
Authors: Frank Leslie D. , Milner Gerald J.
Published: February 2015

Designing for engineering noise control to be applied on turbomachinery packages requires that one be able to isolate and quantify the amount of acoustical energy radiated by each mechanical component individually. The ability to order-rank these noise source contributors allows one to assess the degree of noise control required in order to provide a cost effective noise control design. Conventional sound measurements, especially within buildings, are not adequate to clearly identify individual noise sources and provide order ranking of sources. A measurement technique known as sound intensity does allow one to isolate and measure acoustic power in-situ on individual components. The sound intensity technique in conjunction with sound pressure level predictions was utilized by Nova Corporation of Alberta to assess the major noise source contributors on 10.6MW and 24.9MW turbomachinery packages. The test results clearly indicated which components required selective noise control in order to achieve optimum and cost effective silencing.
Tip Flow Fields in a Low Aspect Ratio Transonic Compressor
Authors: Russler P. , Rabe D. , Cybyk B. , Hah C.
Published: February 2015

Experimental data and computational predictions are used to characterize the tip flow field of a high performance, low aspect ratio, transonic compressor. Flow structures near the first stage blade tip are monitored experimentally using two different data acquisition schemes. High frequency pressure and laser fringe anemometry data are used to experimentally define the tip flow structure. The high frequency pressure data were acquired with an array of pressure transducers mounted in the rotor casing. Laser data were acquired through a window in the same position. The transducer and laser data adequately define the shock structure at the tip. Both the movement of the shock wave in the blade passage during changes in compressor loading and the interaction between the shock wave and the tip leakage vortex are detected. Similar flow structures and compressor loading effects are numerically predicted using a three-dimensional Navier-Stokes algorithm. A fundamental understanding of the flow field at the blade tip is obtained using these three complementary methods.
Viscous Flow Field Computations for the VKI–1 Turbine Cascade Using Different Turbulence Models
Authors: Lenke L. J. , Reichert A. W. , Simon H.
Published: February 2015

The influence of the turbulence modelling on viscous flow field calculation results has often been discussed in the past. For a meaningful comparison of different turbulence models the access to reliable measurement data is necessary. The plane VKI–1 turbine profile has been investigated experimentally in many publications. Therefore this turbine profile is chosen for transonic 2D flow field calculations using three different turbulence models. The algebraic model of Baldwin and Lomax, the Standard k–ϵ model with wall functions and a low–Reynolds number model are considered in this investigation.

The main differences between the models become apparent in the trailing edge region. The turbulence modelling influences the boundary layer thickness and the shape of the shear layers and the separation region in the wake flow. For the high Mach numbers appearing in this region, a strong influence on the flow field due to small shear layer changes has been found.
Pressure-Sensitive Paint Investigation for Turbomachinery Application
Authors: Sabroske K. , Rabe D. , Williams C.
Published: February 2015

Two preliminary tests are discussed which investigate the feasibility of using pressure-sensitive paint (PSP) technology to acquire blade surface pressures in turbomachinery. The first test determined the prospect of using PSP in an operational environment. In this test, PSP was applied to a first stage rotor blade of a state-of-the-art transonic compressor. The paint survived the normal operating temperature, pressure, and centrifugal forces present in this compressor at rotational speeds up to 13,000 RPM. The second test investigated techniques to acquire blade surface pressure data. Suction surface intensity measurements were acquired from a low speed, high-aspect ratio compressor using a back illuminated charge coupled device (CCD) camera while the compressor was rotating at 1500 RPM. An optical derotating mechanism was used to hold the rotor blade image stationary while acquiring PSP data. Both experiments demonstrate that PSP is a viable technique to acquire blade surface pressure data in full scale compressor testing. Special considerations required in applying PSP techniques to turbomachinery are also reported.
Fiber Distribution in Reinforced Ceramic Rotating Discs
Authors: Hild Francois , Leckie Frederick A.
Published: February 2015

Fiber pull-out of fiber reinforced brittle matrix composites is an indication of final failure. The onset of this failure mechanism can be predicted using Continuum Damage Mechanics. After deriving a damage model from a uniaxial approach, different configurations are analyzed through analytical and numerical (F.E. calculations) methods. An extension to fibers in two perpendicular directions is proposed and the failure strength of a rotating disc structure is estimated. The results of the calculations are used to define an optimal fiber distribution in the radial and circumferential directions.
Measurement of Gust Response on a Turbine Cascade
Authors: Kurkov A. P. , Lucci B. L.
Published: February 2015

The paper presents benchmark experimental data on a gust response of an annular turbine cascade. The experiment was particularly designed to provide data for comparison with the results of a typical linearized gust-response analysis. Reduced frequency, Mach number, and incidence were varied independently. Except for the lowest reduced frequency, the gust velocity distribution was nearly sinusoidal. For the high inlet-velocity series of tests, the cascade was near choking. The mean flow was documented by measuring blade surface pressures and the cascade exit flow. High-response pressure transducers were used to measure the unsteady pressure distribution. Inlet-velocity components and turbulence parameters were measured using hot wire. In addition to the synchronous time-average pressure spectra, typical power spectra are included for several representative conditions.
Design and Flow Field Calculations for Transonic and Supersonic Radial Inflow Turbine Guide Vanes
Authors: Reichert A. W. , Simon H.
Published: February 2015

The design of radial inflow turbine guide vanes depends very much on the discharge conditions desired, especially if the choking mass flow is reached. Because of the choking mass flow condition and supersonic discharge Mach numbers, an inverse design procedure based on the method of characteristics is presented. Various designs which correspond to different discharge Mach numbers are shown. Viscous and inviscid flow field calculations for varying discharge conditions show the properties of the guide vanes at design and off–design conditions.

In a previous paper (Reichert and Simon 1994), an optimized design for transonic discharge conditions has been published. In the present paper, additional results concerning the optimum design are presented. For this optimum design an advantageous adjusting mechanism for a variable geometry guide vane has been developed. The effect of guide vane adjustment on the discharge conditions has been investigated using viscous flow field calculations.
Heat Transfer Predictions for Two Turbine Nozzle Geometries at High Reynolds and Mach Numbers
Authors: Boyle R. J. , Jackson R.
Published: February 2015

Predictions of turbine vane and endwall heat transfer and pressure distributions are compared with experimental measurements for two vane geometries. The differences in geometries were due to differences in the hub profile, and both geometries were derived from the design of a high rim speed turbine (HRST). The experiments were conducted in the Isentropic Light Piston Facility (ILPF) at Pyestock at a Reynolds No. of 5.3 × 106, a Mach No. of 1.2, and a wall-to-gas temperature ratio of 0.66. Predictions are given for two different steady state three-dimensional Navier-Stokes computational analyses. C-type meshes were used, and algebraic models were employed to calculate the turbulent eddy viscosity. The effects of different turbulence modeling assumptions on the predicted results are examined. Comparisons are also given between predicted and measured total pressure distributions behind the vane. The combination of realistic engine geometries and flow conditions proved to be quite demanding in terms of the convergence of the CFD solutions. An appropriate method of grid generation, which resulted in consistently converged CFD solutions, was identified.