bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Historical Development of the Centrifugal Impeller
Authors: Engeda Abraham
Published: December 2014

The centrifugal impeller has been in existence for over two hundred years but its perfection and rapid development occurred only in the last sixty years. This paper deals with the early development of the centrifugal impeller in the last and early this century.

The centrifugal impeller is found in centrifugal pumps and compressors. Next to the electric motor, centrifugal pumps and compressors are believed to be the most widely used machines of our time. The field of application of these rotary machines has been continually widening, as they are developed for handling a wider range of liquids and gases at higher pressure and greater temperatures, and whole industries become more and more dependent on them.

The first centrifugal impeller with ten wooden double curved blades and dating back to the fifth century was found in 1772 in an abandoned Portuguese copper mine in San Dominigos. Centrifugal fans had been used for mine ventilation as early as in the sixteenth century.

The invention of the centrifugal impeller is a disputed issue whether the credit goes to Leonardo Da Vinci (1452–1519), who suggested the idea of using centrifugal force for lifting liquid, or to Johann Jordan about 1680. Most place the origin of the centrifugal impeller with Denis Papin in 1689. The importance of Papin’s contribution lies in his understanding of the concept of creating a forced vortex within a circular, or spiral casing by means of blades. Following Papin, Kernelien Le Demour in 1732 and Daniel Gabriel Fahrenheit in 1736 described other designs for centrifugal impellers, but there is no evidence of their practical use.

Euler presented in his 1754 memoir an idealized theoretical application of Newton’s law to centrifugal impellers, based on a conceptualization of his tubular turbine run backwards and now universally known as the “Euler equation”. His publication caused a great development of hydraulic turbines in the eighteenth century, but did little to influence the development of centrifugal impellers, which had to gradually develop through tedious cut-and-try methods. The one thing Euler contributed was to initiate a true mathematical inquiry into the employment of centrifugal force as a means of raising fluid. About the same time as Euler, John Smeaton introduced in 1752 the study of turbomachinery by models. He also defined power as equivalent to the rate of lifting of a weight, a concept that is still fundamental in thermo-fluids.

Today both centrifugal pumps and compressors have reached efficiency levels above 90% and are built in sizes from a few Watts to Megawatts. This paper traces the early historical development of the centrifugal impeller. Factors that promoted and hindered the early development are also discussed.
Analysis of the Transonic Flow at the Inlet of a High Pressure Ratio Centrifugal Impeller
Authors: Eisenlohr Gernot , Dalbert Peter , Krain Hartmut , Pröll Hartwig , Richter Franz-Arno , Rohne Karl-Heinz
Published: December 2014

In an industrial research project of German and Swiss Turbo Compressor manufacturers a high pressure ratio centrifugal impeller was designed and investigated. Performance measurements and extensive laser measurements (L2F) of the flow field upstream, inside and downstream of the rotor have been carried out. In addition to that, 3D calculations have been performed, mainly for the design point. Some earlier results have been presented by Krain et al., 1995.

With four different viscous 3D-solvers, used in companies of the group, calculations for the design speed were carried out to investigate the suitability of these programs in the various design procedures.

Special attention was given to the area from rotor inlet up to the splitter blades. The results for the flow field obtained with the four viscous 3D-Solvers are compared with one another and with the L2F-measurements.
Gas Turbine Development in Sweden After 1945: A Historical Review
Authors: Thoren Kjell T. E.
Published: December 2014

The gas turbine development history of Sweden is exciting. By international comparison Sweden and its gas turbine manufacturers are small but can nevertheless claim periods with the worlds highest output, or highest efficiency large industrial gas turbine respectively.

Sweden has always created its own military aircraft and fitting, high performance engines are developed in Sweden in license cooperation with large international manufacturers. The Swedish Air Force ranked number four in the world during the 60s.

Pioneering contributions were also made with small gas turbines, such as high speed turbogenerators in hybrid propulsion systems for cars and trucks.

Professionals know that gas turbine development success does not come easy. A lot of setbacks have to be mastered. The size of the crew is not always significant in the process.
Heat Transfer Coefficient Measurements of Film-Cooling Holes With Expanded Exits
Authors: Gritsch M. , Schulz A. , Wittig S.
Published: December 2014

Detailed measurements of heat transfer coefficients in the nearfield of three different film-cooling holes are presented. The hole geometries investigated include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fan-shaped and a laidback fanshaped hole). They were tested over a range of blowing ratios M = 0.25…1.75 at an external crossflow Mach number of 0.6 and a coolant-to-mainflow density ratio of 1.85. Additionally, the effect of the internal coolant supply Mach number is addressed.

Temperatures of the diabatic surface downstream of the injection location are measured by means of an infrared camera system. They are used as boundary conditions for a finite element analysis to determine surface heat fluxes and heat transfer coefficients. The superposition method is applied to evaluate the overall film-cooling performance of the hole geometries investigated.

As compared to the cylindrical hole, both expanded holes show significantly lower heat transfer coefficients downstream of the injection location, particularly at high blowing ratios. The laidback fanshaped hole provides a better lateral spreading of the injected coolant than the fanshaped hole which leads to lower laterally averaged heat transfer coefficients. Coolant passage crossflow Mach number affects the flowfield of the jet being ejected from the hole and, therefore, has an important impact on film-cooling performance.
Analysis of a Gas Turbine Cycle With Partial Oxidation
Authors: Korobitsyn M. A. , Kers P. W. , Hirs G. G.
Published: December 2014

This paper addresses the use of the partial oxidation process within a gas turbine cycle. In a partial oxidation reaction fuel is oxidized in a sub-stoichiometric atmosphere at a pressure and a temperature similar to those in the combustion chamber of a conventional turbine. Following the sub-stoichiometric stage, oxidation of the fuel is completed in the final stage. The absence of excess air in the first stages makes it possible to reduce the work required by the compressor and to decrease NOx formation. To assess the partial oxidation concept, several gas turbine systems were simulated and optimized. The results of the comparison study and exergy analysis of the cycles considered are presented.
Experimental Investigation of Boundary Layer Behavior in a Simulated Low Pressure Turbine
Authors: Sohn Ki H. , Shyne Rickey J. , DeWitt Kenneth J.
Published: December 2014

A detailed investigation of the flow physics occurring on the suction side of a simulated Low Pressure Turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the pressure distribution of an actual LPT blade onto a flat plate. The experiments were carried out at Reynolds numbers of 100,000 and 250,000 with three levels of freestream turbulence. The main emphasis in this paper is placed on flow field surveys performed at a Reynolds number of 100,000 with levels of freestream turbulence ranging from 0.8% to 3%. Smoke-wire flow visualization data was used to confirm that the boundary layer was separated and formed a bubble. The transition process over the separated flow region is observed to be similar to a laminar free shear layer flow with the formation of a large coherent eddy structure. For each condition, the locations defining the separation bubble were determined by careful examination of pressure and mean velocity profile data. Transition onset location and length determined from intermittency profiles decrease as freestream turbulence levels increase. Additionally, the length and height of the laminar separation bubbles were observed to be inversely proportional to the levels of freestream turbulence.
Investigation of the 3-D Flow Structure in a High-Speed Annular Compressor Cascade for Tip Clearance Effects
Authors: Doukelis A. , Mathioudakis K. , Papailiou K.
Published: December 2014

The results of an experimental investigation of the flow in a high-speed annular compressor cascade with a hub tip clearance gap and a rotating hub wall are presented 3-D flow measurements are conducted by means of LDA and five hole probes. Detailed flow field data are presented at successive axial planes in a blade passage. Blade surface pressure distributions are also used, to support the interpretation of the in-passage measurements. The features of the clearance flow are captured and discussed. Results are shown for two sizes of the tip clearance gap, while relative wall motion is present. The features of the flow revealed by the present investigation are compared to existing information from low speed studies and it is concluded that the basic physical mechanisms known still prevail for flows which are closer to actual operating compressor flows.
Multistage Centrifugal Compressor Surge Analysis: Part II — Numerical Simulation and Dynamic Control Parameters Evaluation
Authors: Arnulfi Gianmario L. , Giannattasio Pietro , Giusto Cristiana , Massardo Aristide F. , Micheli Diego , Pinamonti Piero
Published: December 2014

This paper describes, from a theoretical point of view, the behaviour of compression systems during surge and the effect of passive and active control devices on the instability limit of the system.

A lumped parameter model is used to simulate the compression system described in Part I of this work (Arnulfi et al., 1998), based on an industrial multistage centrifugal compressor. A comparison with experimental results shows that the model is accurate enough to describe quantitatively all the features of the phenomenon.

A moveable wall control system is studied in order to suppress surge in the compressor. Passive and active control schemes are analysed; they both address directly the dynamic behaviour of the compression system to displace the surge line to lower flow rates. The influence of system geometry and compressor speed is investigated; the optimum values of the control parameters and the corresponding increase in the extent of the stable operating range are presented in the paper.
Scaling of Film Cooling Discharge Coefficient Measurements to Engine Conditions
Authors: Rowbury D. A. , Oldfield M. L. G. , Lock G. D. , Dancer S. N.
Published: December 2014

This paper discusses the need and the procedure for scaling discharge coefficient measurements made in an ambient temperature experiment to render them applicable to the engine situation. Among the dimensionless parameters affecting the discharge coefficients of film cooling holes are the Reynolds number and the coolant Mach number.

Experiments have been conducted in a large scale annular blowdown cascade of film cooled nozzle guide vanes. The coolant system design, using a heavy ‘foreign gas’ (an SF6/Ar mixture) at ambient temperatures, allows the coolant-to-mainstream density ratio and blowing parameters to be matched to engine values.

By using elevated pressure tests, the effect of varying the coolant Reynolds number without external flow is observed experimentally and these results are then used to correct the discharge coefficients measured on the vane with external crossflow. Data is presented and discussed for two cooling hole geometries, namely cylindrical and fanshaped holes.
Predictions of the Effect of Roughness on Heat Transfer From Turbine Airfoils
Authors: Tolpadi Anil K. , Crawford Michael E.
Published: December 2014

The heat transfer and aerodynamic performance of turbine airfoils are greatly influenced by the gas side surface finish. In order to operate at higher efficiencies and to have reduced cooling requirements, airfoil designs require better surface finishing processes to create smoother surfaces. In this paper, three different cast airfoils were analyzed: the first airfoil was grit blasted and codep coated, the second airfoil was tumbled and aluminide coated, and the third airfoil was polished further. Each of these airfoils had different levels of roughness. The TEXSTAN boundary layer code was used to make predictions of the heat transfer along both the pressure and suction sides of all three airfoils. These predictions have been compared to corresponding heat transfer data reported earlier by Abuaf et al. (1997). The data were obtained over a wide range of Reynolds numbers simulating typical aircraft engine conditions. A three-parameter full-cone based roughness model was implemented in TEXSTAN and used for the predictions. The three parameters were the centerline average roughness, the cone height and the cone-to-cone pitch. The heat transfer coefficient predictions indicated good agreement with the data over most Reynolds numbers and for all airfoils-both pressure and suction sides. The transition location on the pressure side was well predicted for all airfoils; on the suction side, transition was well predicted at the higher Reynolds numbers but was computed to be somewhat early at the lower Reynolds numbers. Also, at lower Reynolds numbers, the heat transfer coefficients were not in very good agreement with the data on the suction side.
A Conjugate 3-D Flow and Heat Transfer Analysis of a Thermal Barrier Cooled Turbine Guide Vane
Authors: Bohn Dieter E. , Becker Volker J.
Published: December 2014

This paper presents the numerical investigations of the flow and heat transfer of two configurations of a transonic turbine guide vane. The basic configuration is a vane with convection cooling. The second configuration is additionally coated with a thermal barrier consisting of ZrO2. The results are obtained with a conjugate heat transfer and flow computer code that has been developed at the Institute of Steam and Gas Turbines. Measurement data is available for the basic configuration and the computational results are compared to the experimental results.

The results show very good agreement between calculated and measured vane surface temperatures. The trailing edge turns out to be subjected to high thermal loads as it is too thin to be cooled effectively. Secondary flow phenomena like the passage vortex and the corner vortex and their impact on the temperature distribution are discussed.

The ZrO2 coating is calculated for a thickness of 300μm. The substrate material temperatures are lowered by about 20 K–29 K in the stagnation point area and by about 27 K–43 K in the shock area on the suction side. At the trailing edge, the coating on the suction side and on the pressure side hardly influences the metal temperature.
Effects of the Rotor Tip Leakage in a Transonic Turbine With Long Blades
Authors: Št’astný Miroslav , Matas Richard , Šafařík Pavel , Jung Alexander R. , Mayer Jürgen F. , Stetter Heinz
Published: December 2014

A study of the flow in a transonic turbine stage with long and strongly twisted rotor blades is presented. The focus is on the flow in the near tip region of the blade-to-blade passage of the rotor. The flow has been modelled experimentally in a transonic wind tunnel and numerically by means of 2D and 3D Navier-Stokes equation solvers.

The profiles of the rotor cascades are characterized by law turning angles and a high-velocity exit flow. Detailed flow measurements have been carried out and analysed. A comparison has been made between the experimental and numerical results, and is discussed in detail.

The design and test data of the flow through the upper sections of the span are presented. The effects of the tip leakage flow are evaluated and the three-dimensional patterns of the main flow are estimated. Other points of interest are the results of 3D Navier-Stokes analysis of the stage flow as compared to 2D simulations and wind tunnel experiments, together with the question of the limitations of the individual methods as they all use approximations to the actual flow in the turbine stage.
Nonlinear Model Predictive Control of a Laboratory Gas Turbine Installation
Authors: Vroemen B. G. , van Essen H. A. , van Steenhoven A. A. , Kok J. J.
Published: December 2014

The feasibility of Model Predictive Control (MPC) applied to a laboratory gas turbine installation is investigated. MPC explicitly incorporates (input- and output-) constraints in its optimizations, which explains the choice for this computationally demanding control strategy. Strong nonlinearities, displayed by the gas turbine installation, cannot always be handled adequately by standard linear MPC. Therefore, we resort to nonlinear methods, based on successive linearization and nonlinear prediction as well as the combination of these. We implement these methods, using a nonlinear model of the installation, and compare them to linear MPC. It is shown that controller performance can be improved, without increasing controller execution-time excessively.
Effect of Air Extraction for Cooling and/or Gasification on Combustor Flow Uniformity
Authors: Wang T. , Kapat J. S. , Ryan W. R. , Diakunchak I. S. , Bannister R. L.
Published: December 2014

Reducing emissions is an important issue facing gas turbine manufacturers. Almost all of the previous and current research and development for reducing emissions has focused, however, on flow, heat transfer, and combustion behavior in the combustors or on the uniformity of fuel injection without placing strong emphasis on the flow uniformity entering the combustors. In response to the incomplete understanding of the combustor’s inlet air flow field, experiments were conducted in a 48% scale, 360° model of the diffuser-combustor section of an industrial gas turbine. In addition, the effect of air extraction for cooling or gasification on the flow distributions at the combustors’ inlets was also investigated. Three different air extraction rates were studied: 0% (baseline), 5% (airfoil cooling), and 20% (for coal gasification). The flow uniformity was investigated for two aspects: (a) global uniformity, which compared the mass flow rates of combustors at different locations relative to the extraction port, and (b) local uniformity, which examined the circumferential flow distribution into each combustor. The results indicate that even for the baseline case with no air extraction there was an inherent local flow aonuniformity of 10 ∼ 20% at the inlet of each combustor due to the complex flow field in the dump diffuser and the blockage effect of the cross-flame tube. More flow was seen in the portion further away from the gas turbine center axis. The effect of 5% air extraction was small. Twenty-percent air extraction introduced approximately 35% global flow asymmetry diametrically across the dump diffuser. The effect of air extraction on the combustor’s local flow uniformity varied with the distances between the extraction port and each individual combustor. Longer top hats were installed with the initial intention of increasing flow mixing prior to entering the combustor. However, the results indicated that longer top hats do not improve the flow uniformity; sometimes, adverse effects can be seen. Although a specific geometry was selected for this study, the results provide sufficient generality to benefit other industrial gas turbines.
A Fully Three-Dimensional Inverse Method for Turbomachinery Blading With Navier-Stokes Equations
Authors: Wang Zhengming , Cai Ruixian , Chen Hongji , Zhang Dong
Published: December 2014

A new numerical method for solving fully three-dimensional inverse shape design problem of turbomachinery blading has been developed. The general inverse problem refers to the problem in which the pressure distributions on suction and pressure surfaces of blade are given, but the corresponding blade profile is unknown. In this paper, the calculations are based on the 3D Navier-Stokes equations expressed in terms of nonorthogonal curvilinear coordinates and corresponding nonorthogonal velocity components, and the explicit time marching algorithm and Baldwin-Lomax turbulence model are adopted. A special treatment for boundary conditions on blade surfaces is employed to satisfy the given pressure distribution. In computational process, an initial blade profile is supposed at starting, and then the blade surfaces will move regularly with time steps in the time marching process until the convergence is reached. The movement velocities at every point of blade surfaces are obtained from the solution of the Navier-Stokes equations. After each revision of the blade profile, the grid is reconstructed, and the aerodynamic parameters need to be transferred between the old and new grid points by an accurate interpolation method. Thus the viscous inverse problem is solved in a new process. The computational results for two test cases indicate that the method presented in this paper is very effective.
Application of a Three-Dimensional Inverse Method to the Design of a Centrifugal Compressor Impeller
Authors: Demeulenaere Alain , Léonard Olivier , Van den Braembussche René
Published: December 2014

The use of a three-dimensional Euler inverse method for the design of a centrifugal impeller is demonstrated.

Both the blade shape and the endwalls are iteratively designed. The meridional contour is modified in order to control the mean velocity level in the blade channel, while the blade shape is designed to achieve a prescribed loading distribution between the inlet and the outlet.

The method salves the time dependent Euler equations in a numerical domain of which some boundaries (the blades or the endwalls) move and change shape during the transient part of the computation, until a prescribed pressure distribution is achieved on the blade surfaces.

The method is applied to the design of a centrifugal compressor impeller, whose hub endwall and blade surfaces are modified by the inviscid inverse method. The real performance of both initial and modified geometries are compared through three-dimensional Navier-Stokes computations.
Measurements of Heat Transfer Characteristics of Gap Leakage Around a Misaligned Component Interface
Authors: Chyu M. K. , Hsing Y. C. , Bunker R. S.
Published: December 2014

In an attempt to understand the effects of leakage through a component-to-component interface on the turbine end wall heat transfer, this paper describes an experimental efforts on examining the detailed heat transfer characteristics near a leaking gap. Geometric misalignment around the gap is modeled by either a forward-facing step or a backward-facing step. Heat transfer measurement here uses a temperature-sensitive fluorescent imaging of a thermographic phosphor (TGP). The TGP technique reveals detailed distribution of local heat transfer coefficient and adiabatic wall temperature in the vicinity of the leakage. The results suggest that, for a given leakage-to-mainstream mass flow ratio, the adiabatic wall temperature closes to the level of leakage temperature and is relatively insensitive to the nature of misalignment. On the outer hand, however, the value of heat transfer coefficient varies strongly with misalignment and streamwise location relative to the gap. Overall, the leakage thickens the approaching boundary layer and significantly extends the length of reattachment downstream compared to the corresponding cases without leakage. To further qualify the TGP technique, which is relatively new for transient measurement of local heat transfer, an analysis toward its efficacy in resolving complex convective system is developed in this study. One of the main advantages that TGP inherits is its capability of determining both heat transfer coefficient and reference temperature based on a single test. Other methods, such as the transient liquid crystal technique, generally require separate tests each with different thermal conditions.
Cost Effective Maintenance of Gas Turbine Machinery in Swedish Navy Fast Surface Attack Ships
Authors: Löfdahl Jan-Olof
Published: December 2014

This paper is a summary of 35 years experience from maintenance, overhaul and repair of the ROLLS-ROYCE Marine PROTEUS Gas Turbine in the Swedish Navy.

The 54 installed PROTEUS Gas Turbines in 18 ships have accumulated nearly 300 000 running hours. The reliability has steadily improved thanks to careful monitoring and intensive improvement programs.

The initial, less than 500 hours average between engine removals has been extended to nearly 3000 hours as of today. Also the number of catastrophic engine failures has decreased.

Although the Spare Parts prices and the Labor Costs per hour have increased over the years the maintenance cost per fired Gas Turbine hour has decreased.

The paper describes the technical and economical aspects together with the cost reducing efforts. The information derives from the Swedish Navy Maintenance and Failure Reporting System, named “MARIS”, and from the VOLVO overhaul workshop annual technical and economical activity report.
Improvements in L2F Anemometry Technique for Inter-Blade Investigations in High-Speed Turbomachinery
Authors: Vouillarmet André , Trebinjac Isabelle
Published: December 2014

This paper presents some problems inherent in the application of a laser two-focus anemometry technique to measurement in high-speed small-scale compressors. Improvements in data processing are described, in relation to reducing the acquisition time. Measurement uncertainties and their possible estimation are discussed. An optimized blade pitch partition during synchronized measurements within rotating blade passages is presented using a prediction of shadow zones. Two examples highlight the resulting benefits both in terms of reduction of the acquisition time and improvement of the azimuthal resolution.
Coal-Biomass Gasification in a Pressurized Fluidized Bed Gasifier
Authors: de Jong W. , Andries J. , Hein K. R. G.
Published: December 2014

In the framework of a multi-national European Joule project, experimental research and modeling concerning co-gasification of biomass and coal in a bubbling pressurized fluidized bed reactor is performed. The impact of fuel characteristics (biomass type, mixing ratio) and process conditions (pressure, temperature, gas residence time, air-fuel ratio and air-steam ratio) on the performance of the gasifier (carbon conversion, fuel gas composition, non-steady state behaviour) was studied experimentally and theoretically.

Pelletized straw and miscanthus were used as biomass fuels. The process development unit has a maximum thermal capacity of 1.5 MW and was operated at pressures up to 10 bar and bed temperatures in the range of 650 °C–900 °C. The bed zone of the reactor is 2 m high with a diameter of 0.4 m and is followed by an adiabatic freeboard, approximately 4 m high with a diameter of 0.5 m.

Time-averaged as well as time-dependent characteristics of the fuel gas were determined experimentally. The results will be compared with the gas turbine requirements provided by a gas turbine manufacturer, one of the partners in the project. The evaluation of the results will ultimately be used to implement and test an adequate control strategy for the pressurized fluidized bed gasifier integrated with a gas turbine combustion chamber.
Dynamic Modeling and Control of Regenerative Gas Turbines
Authors: Camporeale S. M. , Fortunato B. , Dumas A.
Published: December 2014

A non linear dynamic model has been developed in order to simulate the dynamic behavior of single-shaft or multi-shaft regenerative gas turbines. The aim of the work is to provide a fast and reliable model for the synthesis of the controllers and the study of critical dynamic situations. Some significant features characterize the proposed model:

- an efficient one-dimensional model is used in order to properly model a stationary counter-flow regenerator;

- a stage by stage model is provided for the air cooled turbine expansion in order to take into account the blade thermal transients.

The mathematical model and the numerical methodology are described in the paper.

A single-shaft regenerative cycle gas turbine is analyzed. In order to design a multivariable controller for this plant, a linearized model is developed from the non-linear model. The gas turbine is described by the transfer functions that relate the input variables (fuel rate and variable inlet guide vanes) to the state variables (shaft speed and turbine output temperature). Accuracy and effects of non-linearities are described.
CFD Modeling of a Gas Turbine Combustor From Compressor Exit to Turbine Inlet
Authors: Crocker D. Scott , Nickolaus Dan , Smith Clifford E.
Published: December 2014

Gas turbine combustor CFD modeling has become an important combustor design tool in the past few years, but CFD models are generally limited to the flow field inside the combustor liner or the diffuser/combustor annulus region. Although strongly coupled in reality, the two regions have rarely been coupled in CFD modeling. A CFD calculation for a full model combustor from compressor diffuser exit to turbine inlet is described. The coupled model accomplishes two main objectives: 1) implicit description of flow splits and flow conditions for openings into the combustor liner, and 2) prediction of liner wall temperatures. Conjugate heat transfer with nonluminous gas radiation (appropriate for lean, low emission combustors) is utilized to predict wall temperatures compared to the conventional approach of predicting only near wall gas temperatures. Remaining difficult issues such as generating the grid, modeling swirler vane passages, and modeling effusion cooling are also discussed.
Effects of Bulk Flow Pulsations on Film Cooling From Different Length Injection Holes at Different Blowing Ratios
Authors: Seo H. J. , Lee J. S. , Ligrani P. M.
Published: December 2014

Bulk flow pulsations in the form of sinusoidal variations of velocity and static pressure at injectant Strouhal numbers from 0.8 to 10.0 are investigated as they affect film cooling from a single row of simple angle holes. Similar flow variations are produced by potential flow interactions and passing shock waves near turbine surfaces in gas turbine engines. Time-averaged temperature distributions, phase-averaged temperature distributions, adiabatic film cooling effectiveness values, and iso-energetic Stanton numbers show that important alterations to film cooling protection occur as pulsation frequency, coolant Strouhal number, blowing ratio, and non-dimensional injection hole length are changed. Overall, the pulsations affect film performance end behavior more significantly both as L/D decreases, and as blowing ratio decreases.
Experiences From the Joint Development of the GTX100 Turbine Blading
Authors: Gudmundsson Bengt , Nilsson Ulf , Linder Ulf , Shukin Sergey , Afanasiev Igor , Kostege Valery
Published: December 2014

The GTX100 is the most recent industrial gas turbine in the ABB fleet. The development of the GTX100 turbine blading was a joint project involving four companies. A thorough evaluation of various design requirements resulted in the selection of a single shaft three-stage turbine configuration.

The cooling techniques employed for the blading are based on the knowledge from the Russian school of design for gas turbines. These techniques have been verified by a considerable amount of experimental data and field experience over a number of years. To incorporate western manufacturing methods, western suppliers were introduced at an early stage in the development.

Most of the engineering development of the turbine blading was carried out in Russia. In order to achieve efficient cooperation between Russia and Sweden, specialists from both companies were stationed at alternating companies. The verification of the turbine design is divided into two steps. The first step is cold and hot component testing and the second is the overall engine testing.
Performance Analysis of a 50KW Turbogenerator Gas Turbine Engine
Authors: Kim S. Y. , Park M. R. , Cho S. Y.
Published: December 2014

This paper describes on/off design performance of a 50KW turbogenerator gas turbine engine for hybrid vehicle application. For optimum design point selection, a relevant pa4rameter study is carried out. The turbogenerator gas turbine engine for a hybrid vehicle is expected to be designed for maximum fuel economy, ultra low emissions, and very low cost. A compressor, combustor, turbine, and a permanent-magnet generator will be mounted on a single high speed (80,000 rpm) shaft that will be supported on air bearings. As the generator is built into the shaft, gearbox and other moving parts become unnecessary and thus will increase the system’s reliability and reduce the manufacturing cost. The engine has a radial compressor and turbine with design point pressure ratio of 4.0. This pressure ratio was set based on calculation of specific fuel consumption and specific power variation with pressure ratio. For the turbine inlet temperature, a rather conservative value of 1100K was selected. Designed mass flow rate was 0.5 kg/sec. Parametric study of the cycle indicates that specific work and efficiency increase at a given pressure ratio and turbine inlet temperature. Off design analysis shows that the gas turbine system reaches self operating condition at about N/NDP = 0.48. Bleeding air for a turbine stator cooling is omitted considering the low TIT in the present engine and to enable the simple geometric configuration for manufacturing purpose. Various engine performance simulations including ambient temperature influence, surging at part load condition; transient analysis were performed to secure the optimum engine operating characteristics. Surge margin throughout the performance analysis were maintained to be over 50% approximately. Present analysis will be compared with performance test result which is scheduled at the end of 1998.
Effects of Bulk Flow Pulsations on Film Cooling From Spanwise Oriented Holes
Authors: Jung I. S. , Lee J. S.
Published: December 2014

Experimental results are presented which describe the effect of bulk flow pulsations on film cooling from a single row of spanwise oriented holes. The film coolant is injected from the holes with 35 degree inclination angles and 90 degree orientation angles. Static pressure pulsations are produced by rotating vanes made of an array of six shutter blades, which are extended across the span of the exit of the wind tunnel test section. The free-stream velocity is in the form of near-sinusoidal variation and peak-to-peak amplitude is 11%. Changing two parameters which are time-averaged blowing ratio (M = 0.5, 1.0, 2.0) and frequency (f = 0, 36 Hz) gives the corresponding coolant Strouhal numbers in the range from 0 to 3.6. Time-averaged and phase-averaged temperature distributions are measured in spanwise/normal planes, and the adiabatic film cooling effectiveness is evaluated from the adiabatic wall temperature distributions. The results show that the imposed free-stream velocity pulsations generate static pressure difference variations between the plenum chamber and free-stream. These static pressure pulsations result in periodic variation of injectant flow rate and spanwise momentum which cause dramatic alterations in film coolant distributions, trajectories and corresponding adiabatic film cooling effectiveness distributions downstream of injection holes.
Heat Transfer in a Rotating Radial Channel With Swirling Internal Flow
Authors: Glezer B. , Moon H. K. , Kerrebrock J. , Bons J. , Guenette G.
Published: December 2014

This paper presents experimental results for heat transfer in swirling internal flow, obtained in two ways. A test rig simulated a rotating blade’s leading edge internal passage with heated walls and screw-shaped cooling swirl generated by flow introduced through discrete tangential slots. Spatially resolved variations of the surface heat transfer coefficients were measured in the rotating rig using an IR radiometer.

A blade tested in the actual engine environment had similar geometry of the leading edge cooling passage. The blade surface temperatures were mapped in the engine with thermal paints and compared with a traditional convective cooling configuration. The data from the rotating rig and engine measurements are also compared with non-rotating heat transfer results obtained in the hot cascade using a traversing pyrometer at a realistic wall-to-coolant temperature ratio.

The results are presented for realistic rotational numbers, ranging from 0 to 0.023, and for representative Reynolds number of 20,000 based on the channel diameter. The effect of Coriolis forces is evident with the change of direction of the rotation. A slight negative influence of the crossflow, which increased toward the outer radius of the channel, was recorded in the rig test results.

The results presented will assist in better understanding of the screw-shaped swirl cooling technique, providing the next step toward the application of this highly-effective internal cooling method for the leading edges of turbine blades.
Unsteady Heat Transfer in Stator-Rotor Interaction by Two Equation Turbulence Model
Authors: Michelassi V. , Martelli F. , Dénos R. , Arts T. , Sieverding C. H.
Published: December 2014

A transonic turbine stage is computed by means of an unsteady Navier-Stokes solver. A two equation turbulence model is coupled to a transition model based on integral parameters and an extra transport equation. The transonic stage is modeled in two-dimensions with a variable span height for the rotor row. The analysis of the transonic turbine stage with stator trailing edge coolant ejection is carried out to compute the unsteady pressure and heat transfer distribution on the rotor blade under variable operating conditions. The stator coolant ejection allows the total pressure losses to be reduced although no significant effects on the rotor heat transfer are found in both the computer simulation and measurements. The results compare favorably with experiments both in terms of pressure distribution and heat transfer around the rotor blade.
Experimental and Computational Study of the Unsteady Flow in a 1.5 Stage Axial Turbine With Emphasis on the Secondary Flow in the Second Stator
Authors: Walraevens Ralf E. , Gallus Heinz E. , Jung Alexander R. , Mayer Jürgen F. , Stetter Heinz
Published: December 2014

A study of the unsteady flow in an axial flow turbine stage with a second stator blade row is presented. The low aspect ratio blades give way to a highly three-dimensional flow which is dominated by secondary flow structures. Detailed steady and unsteady measurements throughout the machine and unsteady flow simulations which include all blade rows have been carried out. The presented results focus on the second stator flow. Secondary flow structures and their origins are identified and tracked on their way through the passage. The results of the time-dependent secondary velocity vectors as well as flow angles and Mach number distributions as perturbation from the time-mean flow field are shown in cross-flow sections and azimuthal cuts throughout the domain of the second stator. At each location the experimental and numerical results are compared and discussed. A good overall agreement in the time-dependent flow behaviour as well as in the secondary flow structures is stated.
Creep Analysis of High Temperature Components Under Multi-Axial Loading
Authors: Moftakhar Abbas A. , Glinka Grzegorz
Published: December 2014

A simplified solution method that enables the estimation of stresses and strains in high temperature components under creep conditions is presented. The solution is derived based on strain energy density considerations and is applicable to both uniaxial and multiaxial stress states. In particular, this simplified method is developed for an efficient estimation of the cyclic stress-strain history at critical locations which needed for fatigue analysis of hot sections under creep conditions where conventional finite element creep analysis becomes extremely time consuming. The input data necessary to perform this simplified solution are the stresses and strains obtained from a linear elastic analyses. If the finite element method (FEM) is used for the linear elastic analysis of components, then the simplified solution method can be programmed as a post processor file. The file uses the linear elastic FEM results and generates an approximate time-dependent analysis. Presented results illustrates the accuracy of the method by comparing with finite element creep analysis results for several hot sections under creep conditions. Also, it is shown that the computational time needed to perform this solution is far less than the conventional finite element creep analysis.
A Comparison of Measured and Predicted Unsteadiness in a Transonic Fan
Authors: Singh Udai K. , Smith Graham C.
Published: December 2014

The two dimensional, viscous, non-linear unsteady code UNSFLO has been used to model a highly loaded transonic fan stage along a mid-span section. This paper examines the results of this unsteady calculation, and compares with time resolved measurements taken on a continuous flow test rig. The main features of the time resolved experimental data are shown to be captured by the calculation. Comparison of losses for steady and unsteady calculations show that the stator loss is significantly increased by the blade row interaction effects. The origin of static pressure fluctuations within the stator passage has also been examined.
A Near-Field Investigation Into the Effects of Geometry and Compound Angle on the Flowfield of a Row of Film Cooling Holes
Authors: Berger Phillip A. , Liburdy James A.
Published: December 2014

The goal of this study was to determine the effects that hole geometry and compound angle have on the near-field downstream from a row of jets injected into a crossflow. Velocity and vorticity fields are presented in cross-sectional planes oriented perpendicular to the mainstream flow. Instantaneous field measurements were obtained using particle image velocimetry (PIV). Data were recorded at locations of 0, 1, 2, and 3.5 hole diameters downstream of injection for three different hole geometries inclined at 35° to the mainstream flow. These geometries consisted of a cylindrical hole, a 12° laterally-diffused hole, and a 15° forward-expanded hole with compound angles of 0°, 45°, 60°, and 90. Data are presented for a blowing ratio of 1.25 and density ratio of 1. The influences on jet penetration, coverage width, flow structure elevation, and flow structure separation for each configuration are discussed. Vorticity is presented in terms of field distribution and peak magnitudes. These studies show the degradation of the counter-rotating vortex pair into a singular, recirculating structure as the compound angle increases. Peak levels of vorticity are not encountered until between one and two diameters downstream of injection.
Investigating and Resolving Accessory Gearbox Failures on Allison 501-K Series Engines
Authors: Russom Dennis M. , Masincup William E. , Eghtessad John , Schultz Andrew
Published: December 2014

The U. S. Navy uses the Allison 501-K series engines as the prime mover of the Ship Service Gas Turbine Generators (SSGTGs) on DD-963, DDG-993, CG-47 and DDG-51 Class Ships. Historical data shows the engine’s most unreliable component to be the Accessory GearBox (AGB). This paper describes an intensive effort to identify and correct the root cause of the AGB failures and improve overall engine reliability and operational availability.
A Performance Evaluation of a Three Splitter Diffuser and Vaneless Diffuser Installed on the Power Turbine Exhaust of a TF40B Gas Turbine
Authors: Harris Howard , Piñeiro Ivan , Norris Tom
Published: December 2014

A field test was conducted on a three splitter diffuser and a vaneless diffuser (no splitters) to determine, the pressure recovery coefficient, effects on engine performance, exhaust collector temperature distribution, and exhaust gas noise.

This paper presents the cause of the mechanical failure of the three splitter diffuser, basic diffuser design, field test instrumentation, and the test results. The test results found the vaneless diffuser had a higher pressure recovery, created a lower back pressure, and did not raise the exhaust gas temperature (EGT) nor fuel consumption of the engine, as compared to the three splitter diffuser.
Unsteady Wake Effects on Boundary Layer Transition and Heat Transfer Characteristics of a Turbine Blade
Authors: Schobeiri M. T. , Chakka P. , Pappu K.
Published: December 2014

Effect of unsteady wakes on aerodynamic and heat transfer characteristics of a turbine blade in a cascade were analyzed both experimentally and theoretically. Comprehensive aerodynamic data were collected for different wake passing frequencies that are typical of turbomachinery. Hot-wire probes were used for collection of boundary layer data on suction and pressure surfaces of the turbine blade. Heat transfer measurements were made using steady liquid crystal techniques. Boundary layer data were analyzed through intermittency function to get insight into the transition process under unsteady wake flow conditions. The experimental and theoretical results presented in this paper confirm the general validity of the unsteady boundary layer transition model developed by Chakka and Schobeiri (1997). This model is based on a relative intermittency function, which accounts for the effects of periodic unsteady wake flow on the boundary layer transition. Three distinct quantities are identified as primarily responsible for the transition of an unsteady boundary layer. These quantities, which exhibit the basis of the transition analysis presented in this paper, are: (1) relative intermittency, (2) maximum intermittency, and (3) minimum intermittency. To validate the developed transition model, it is implemented in an existing boundary layer code, and the resulting heat transfer coefficients are compared with the experimental data.