bluuebunny/crossref_metadata_2025 huggingface dataset:
A Summary of the Cooled Turbine Blade Tip Heat Transfer and Film Effectiveness Investigations Performed by Dr. D. E. Metzger
Authors: Kim Y. W. , Abdel-Messeh W. , Downs J. P. , Soechting F. O. , Steuber G. D. , Tanrikut S.
Published: February 2015

The clearance gap between the stationary outer air seal and blade tips of an axial turbine allows a clearance gap leakage flow to be driven through the gap by the pressure-to-suction side pressure difference. The presence of strong secondary flows on the pressure side of the airfoil tends to deliver air from the hottest regions of the mainstream to the clearance gap. The blade tip region, particularly near the trailing edge, is very difficult to cool adequately with blade internal coolant flow. In this case, film cooling injection directly onto the blade tip region can be used in an attempt to directly reduce the heat transfer rates from the hot gases in the clearance gap to the blade tip. The present paper is intended as a memorial tribute to the late Professor Darryl E. Metzger who has made significant contributions in this particular area over the past decade. A summary of this work is made to present the results of his more recent experimental work that has been performed to investigate the effects of film coolant injection on convection heat transfer to the turbine blade tip for a variety of tip shapes and coolant injection configurations. Experiments are conducted with blade tip models that are stationary relative to the simulated outer air seal based on the result of earlier works that found the leakage flow to be mainly a pressure-driven flow which is related strongly to the airfoil pressure loading distribution and only weakly, if at all, to the relative motion between blade tip and shroud. Both heat transfer and film effectiveness are measured locally over the test surface using a transient thermal liquid crystal test technique with a computer vision data acquisition and reduction system for various combinations of clearance heights, clearance flow Reynolds numbers, and film flow rates with different coolant injection configurations. The present results reveal a strong dependency of film cooling performance on the choice of the coolant supply hole shapes and injection locations for a given tip geometry.
Aero Engine Test Experience With CMSX-4® Alloy Single Crystal Turbine Blades
Authors: Fullagar Keith P. L. , Broomfield Robert W. , Hulands Mark , Harris Ken , Erickson Gary L. , Sikkenga Steven L.
Published: February 2015

A team approach involving a turbine engine company [Rolls-Royce], its single crystal casting facilities and a superalloy developer and ingot manufacturer [Cannon-Muskegon], utilizing the concepts of simultaneous engineering, has been used to successfully develop CMSX-4 alloy for turbine blade applications. CMSX-4 alloy is a second generation nickel-base single crystal superalloy containing 3% (wt) rhenium (Re) and 70% volume fraction of the coherent γ′ precipitate strengthening phase. Its finely balanced composition offers an attractive range of properties for turbine airfoil applications. In particular the alloy’s combination of high strength in relation to creep-rupture, mechanical and thermal fatigue, good phase stability following extensive high temperature, stressed exposure and oxidation, hot corrosion and coating performance, are attractive for turbine engine applications where engine performance and turbine airfoil durability are of prime importance.

The paper details the single crystal casting process and heat treatment manufacturing development for turbine blades in CMSX-4 alloy. Competitive single crystal casting yields are being achieved in production and extensive vacuum heat treatment experience confirms CMSX-4 alloy to have a practical production solution heat treat / homogenization “window”.

The creep-rupture data-base on CMSX-4 alloy now includes 325 data points from seventeen heats including fourteen 3630 kg (8000 lb) production size heats. An appreciable portion of this data was machined-from-blade (MFB) properties which indicate turbine blade component capabilities based on single crystal casting process, component configuration and heat treatment. The use of hot-isostatic-pressing (HIP) has been shown to eliminate single crystal casting micropores which along with the essential absence of γ/γ′ eutectic phase, carbides, stable oxide, nitride and sulphide inclusions results in remarkably high mechanical fatigue properties, with smooth and particularly notched specimens. The Re addition has been shown to not only benefit creep and mechanical fatigue strength (with and without HIP), but also bare oxidation, hot corrosion (sulphidation) and coating performance.

The high level of balanced properties determined by extensive laboratory evaluation has been confirmed during engine testing the Rolls-Royce Pegasus turbofan.
Topping Combustor Development for Second-Generation Pressurized Fluidized Bed Combined Cycles
Authors: Domeracki W. F. , Dowdy T. E. , Bachovchin D. M.
Published: February 2015

A project team consisting of Foster Wheeler Development Corporation, Westinghouse Electric Corporation, Gilbert/Commonwealth and the Institute of Gas Technology, are developing a Second Generation Pressurized Fluidized Bed System. Foster Wheeler is developing a carbonizer (a partial gasifier) and a pressurized fluidized bed combustor. Both these units operate a nominal 1600°F (870°C) for optimal sulfur capture. Since this temperature is well below the current combustion turbine combustor outlet operating temperature of 2350°F (1290°C) to reach commercialization, a topping combustor and hot gas cleanup (HGCU) equipment must be developed.

Westinghouse is participating in the development of the high temperature gas cleanup equipment and the topping combustor. This paper concentrates on the design and test of the topping combustor. The topping combustor in this cycle must utilize a low heating value syngas from the carbonizer at approximately 1600°F (870°C) and 150 to 210 psi (1.0 to 1.4 MPa). The syngas entering the topping combustor has been previously cleaned of particulates and alkali by the hot gas cleanup (HGCU) system. It also contains significant fuel bound nitrogen present as ammonia and other compounds. The fuel-bound nitrogen is significant because it will selectively convert to NOx if the fuel is burned under the highly oxidizing conditions of standard combustion turbine combustors.

The fuel must be burned with the vitiated air from the pressurized fluidized bed combustor (PFBC). Oxidizer has been cleaned of particulates and alkali by HGCU system, and has also been partially depleted in oxygen. The 1600°F (870°C) oxidizer must also be utilized to cool the combustor as much as possible, though a small amount of compressor discharge air at a lower temperature 700°F (about 370°C) may be used.

The application requirements indicate that a rich-quench-lean (RQL) combustor is necessary and the multi-annular swirl burner (MASB) was selected for further development. This paper provides an update on the development and testing of this MASB combustor. Additionally, Westinghouse has been conducting computational fluid dynamic (CFD) and chemical kinetic studies to assist in the design of the combustor and to help optimize the operation of the combustor. Results of these models are presented and compared to the test results.
Effects of Shock Wave Passage on Heat Transfer in a Transonic Turbine Cascade
Authors: Holmberg D. G. , Reid T. , Kiss T. , Moses H. L. , Ng W. F. , Diller T. E.
Published: February 2015

Results from a new facility for measuring heat transfer in transonic turbine cascades are repotted. An air heater has been built into the blow-down wind tunnel to heat the main flow for a 20 second run time. This allows control of the direction and magnitude of the heat transfer into the blade throughout the tests. A Heat Flux Microsensor was inserted into the blade to measure simultaneous surface heat flux and temperature. Measurements were made on the suction surface of the blades toward the trailing edge. Because of the long run times (20 s), the adiabatic wall temperature could be determined directly from the measured surface temperature and heat flux. Simultaneous pressure measurements were made with a Kulite transducer at the same distance from the leading edge to document shock passage. A separate shock tube was used to generate a shock wave which was introduced into the test section in front of the cascade. This shock was carried over the blade by the main flow. The resulting changes in heat flux correlated strongly with the unsteady pressure changes. An overall increase of 1.5 W/cm2 in heat flux was recorded for a pressure increase of 7 kPa during the initial passage of the shock.
The Design and Calibration of a Heat-Fluxmeter for Gas Turbine Studies
Authors: Ivey Paul C.
Published: February 2015

This paper details the design, construction and calibration of a heat-fluxmeter to measure at one end of an idealised model of an aero-engine drive shaft. The constraints on instrument design of manufacture and calibration, together with the matching of instrument and measurement characteristics are discussed.

Sample heat-transfer results based upon fluxmeter measurements are presented. A model for the heat-transfer to the nose-cone of an aero-engine for anti-icing applications, derived from these results, is shown to compare favourably with analysis of engine icing performance test data.
Air Temperature Rises in Compressor and Turbine Stator Wells
Authors: Bayley F. J. , Childs P. R. N.
Published: February 2015

This paper considers the fluid dynamic principles determining the consequences of mainstream fluid ingressing to the comparatively shallow space between the rotor disc and the ring used in many designs of axial-flow turbo-machine, especially compressors, to support the stator blades at their inner ends. Windage power due to friction between this fluid and the bounding walls of this annular space, or ‘stator well’, can lead to substantial temperature rises in this region. The feasible range of flow regimes is first developed, especially as influenced by leakage through the internal seals beneath the stators separating adjacent wells. Using published data, on windage coefficients and the effects of geometry on the flow through the wells, very little of which has been obtained from truly representative flow conditions or geometries, calculations have been made to estimate the likely rises in temperature to be anticipated in realistic well designs. Leakage rates appear, not unexpectedly, to be crucial in determining these temperature rises, but the geometries of the system are little less critical, in particular the ratio of the outer to inner radiuses of the stator well and the outer peripheral clearances between rotor and stator surfaces. Leakage into a well from its adjacent neighbour is shown to lead to higher temperature rises downstream of the labyrinth seal and the possible effects of recirculation through stator wells from the mainstream boundary layer could be significant.
Performance Prediction of Centrifugal Compressors During the Conceptual Engineering Phase
Authors: Hånde Bjørn M.
Published: February 2015

This paper presents a method for performance prediction of a potential centrifugal compressor, based on the process data at the design point. The procedure is based on a study of the design practice for a number of vendors for the North Sea hydrocarbon processing industry. The study shows that todays compressor vendors tend to follow the classic design rules developed in the early sixties. These design rules can be applied on the process data from a plant simulation to create an imaginary compressor. A mean line prediction method is used to predict the off-design performance over the total operating range of the compressor. A successful prediction depends on the finally chosen compressor being well designed for the given operating point. The procedure, in the form of PC-based programs, has been applied in conceptual studies and modification studies of off-shore compression plants.
Air Extraction in a Gas Turbine for Integrated Gasification Combined Cycle (IGCC): Experiments and Analysis
Authors: Kapat J. S. , Agrawal A. K. , Yang T.-T.
Published: February 2015

This paper presents an investigation of extracting air from the compressor discharge of a heavy-frame gas turbine. The study was aimed to verify results of an approximate analysis: whether extracting air from the turbine wrapper would create unacceptable nonuniformity in the flow field inside the compressor discharge casing. A combined experimental and computational approach was undertaken. Cold flow experiments were conducted in an approximately one-third scale model of a heavy-frame gas turbine; a closely approximated 3-D computational fluid dynamic analysis was also performed. This study substantiated the earlier prediction that extracting air from the turbine wrapper would be undesirable although this method of air extraction is simple to retrofit. Prediffuser inlet is suggested as an alternate location for extracting air. The results show that not only the problem of flow non-uniformity was alleviated with this alternate scheme, but the frictional power loss in the compressor discharge casing was also reduced by a factor of two.
Prediction of Turbulent Flow and Heat Transfer in a Rotating Square Duct With a 180 deg. Bend
Authors: Sathyamurthy Prabhu S. , Karki Kailash C. , Patankar Suhas V.
Published: February 2015

This paper reports the results of a numerical study on the fluid flow and heat transfer in a rotating square duct with 180 deg. bend. The computations are based the standard k-ε turbulence model with wall functions. At a fixed Reynolds number, results have been obtained over a range of Rotation numbers and coolant-to-wall temperature ratios. These results reflect the complex interaction of Coriolis forces, buoyancy forces, and curvature effects. For the outward leg, rotation causes the heat transfer enhancement on the trailing surface and degradation on the leading surface. However, in the inward leg, there is heat transfer degradation on the trailing surface and enhancement on the leading edge. The buoyancy forces cause further degradation in the heat transfer on the leading surface and enhancement on the trailing surface of the outward leg.
Forced Harmonic Response of Grouped Blade Systems: Part I — Discrete Theory
Authors: Wagner L. F. , Griffin J. H.
Published: February 2015

The vibration of grouped blades on a flexible disk cannot be analyzed using procedures developed for individual, uncoupled groups. The bladed-disk system must be considered either in whole, or as a structure composed of cyclically-symmetric sectors. The latter approach, while being computationally more economical, is more complicated to implement because both the structural system and the applied forces must be transformed to a system based on the geometry of a single sector. However, the sector transformation permits a natural ordering of the modes that cannot be obtained from a complete system model. This paper describes the development of the sector model, and the associated transformation of the applied harmonic forces typically prevalent in turbomachinery. The displacements are expressed in a series of the natural modes of a transformed sector, and expressions are developed for maximum displacements of the complete structure. This approach leads to an easier interpretation of the analytical results and an improved physical understanding of the response. For example, it is shown that a single harmonic, or engine-order excitation, can cause response in only a restricted subset of modes.
Numerical Investigation of Stall Flutter
Authors: Ekaterinaris John A. , Platzer Max F.
Published: February 2015

Unsteady, separated, high Reynolds number flow over an airfoil undergoing oscillatory motion is investigated numerically. The compressible form of the Reynolds-averaged governing equations is solved using a high-order, upwind biased numerical scheme. The turbulent flow region is computed using a one-equation turbulence model. The computed results show that the key to the accurate prediction of the unsteady loads at stall flutter conditions is the modeling of the transitional flow region at the leading edge. A simplified criterion for the transition onset is used. The transitional flow region is computed with a modified form of the turbulence model. The computed solution, where the transitional flow region is included, shows that the small laminar/transitional separation bubble forming during the pitch-up motion has a decisive effect on the near wall flow and the development of the unsteady loads. Detailed comparisons of computed fully turbulent and transitional flow solutions with experimental data are presented.
Rotating Stall in a Single Stage Axial Flow Compressor
Authors: Poensgen C. A. , Gallus H. E.
Published: February 2015

This paper describes the results on an experimental investigation of rotating stall flow inside a single stage axial flow compressor. Tests were carried out in two steps. First, measurements were taken to investigate the transition process into rotating stall. The compressor starts into rotating stall via the “modal route” with a single rotating stall cell. Further throttling yields to a two-cell shape followed by a significant outlet pressure drop. Both transition processes are discussed in detail. Results from the Moore-Greitzer theory are compared with measured data.

In a second step measurements were taken to determine the three-dimensional unsteady structure of a full developed rotating-stall cell. Based on unsteady total pressure and threedimensional hot-wire data, the structure of a rotating stall cell could be resolved in detail upstream and downstream the rotor. A typical part-span stall was found. By inserting the measured data into the Euler-equations convective and unsteady effects on the pressure fluctuations can be isolated. A dependence between the radial flow inside the stall cell and the unsteady flow accelerations was found.
Flow Field and Performance Characteristics of Combustor Diffusers: A Basic Study
Authors: Hestermann R. , Kim S. , Khaled A. Ben , Wittig S.
Published: February 2015

Results of a detailed study concerning the influence of geometrical as well as of fluid mechanic parameters on the performance of a plane model combustor diffuser in cold flow are presented. For a qualitative insight into the complex flow field inside the pre-diffuser, the sudden expansion region and into the flow field around the flame tube dome, results of a flow visualization study with the hydrogen bubble method as well as with the ink jet method are presented for different opening angles of the pre-diffuser and for different flame tube distances. Also, quantitative data from detailed measurements with LDV and conventional pressure probes in a geometrically similar air driven setup are presented. These data clearly demonstrate the effect of boundary layer thickness as well as the influence of different turbulence levels at the entry of the pre-diffuser on the performance characteristics of combustor diffusers.

The possibility of getting an unseparated flow field inside the pre-diffuser even at large opening angles by appropriately matching the diffuser’s opening angle and the flame tube distance is demonstrated. Also, for flows with an increased turbulence level at the entrance — all other conditions held constant — an increased opening angle can be realised without experiencing flow separation. The comparison of the experimental data with predictions utilizing a finite-volume-code based on a body-fitted coordinate system for diffusers with an included total opening angle less than 18° demonstrates the capability of describing the flow field in combustor diffusers with reasonable accuracy.
Experimental and Computational Results From the Nasa Lewis Low-Speed Centrifugal Impeller at Design and Part Flow Conditions
Authors: Chriss Randall M. , Hathaway Michael D. , Wood Jerry R.
Published: February 2015

The NASA Lewis Low-Speed Centrifugal Compressor (LSCC) has been investigated with laser anemometry and computational analysis at two flow conditions: the design condition as well as a lower mass flow condition. Previously reported experimental and computational results at the design condition are in the literature (Hathaway et al. 1993). In that paper extensive analysis showed that inducer blade boundary layers are centrifuged outward and entrained into the tip clearance flow and hence contribute significantly to the throughflow wake. In this report results are presented for a lower mass flow condition along with further results from the design case.

The data set contained herein consists of three-dimensional laser velocimeter results upstream, inside and downstream of the impeller. In many locations data have been obtained in the blade and endwall boundary layers. The data are presented in the form of throughflow velocity contours as well as secondary flow vectors.

The results reported herein illustrate the effects of flow rate on the development of the throughflow momentum wake as well as on the secondary flow. The computational results presented confirm the ability of modern computational tools to accurately model the complex flow in a subsonic centrifugal compressor. However, the blade tip shape and tip clearance must be known in order to properly simulate the flow physics. In addition, the ability to predict changes in the throughflow wake, which is largely fed by the tip clearance flow, as the impeller is throttled should give designers much better confidence in using computational tools to improve impeller performance.
Experimental and Numerical Investigation of Shock Wave Within a Swept Shrouded Propfan Rotor
Authors: Helming Klaus
Published: February 2015

Laser velocity measurements are conducted in a swept propfan rotor in order to investigate the local transonic flow region on the suction surface at high subsonic inlet Mach numbers. The velocity measurements are accompanied by a 3D-Navier-Stokes calculation for a selected operating point. The good agreement between computed and measured flow field gives some confidence to study the local three-dimensional passage shock on the suction surface by using the numerical procedure. Apart of the computed three-dimensional shock structure is investigated in detail. By considering streamlines it is concluded whether the shock wave is normal or oblique. The results are compared with the one-dimensional shock conditions.
Osborne Reynolds: Energy Methods in Transition and Loss Production — A Centennial Perspective
Authors: Moore John , Moore Joan G.
Published: February 2015

Osborne Reynolds’ developments of the concepts of Reynolds averaging, turbulence stresses, and equations for mean kinetic energy and turbulence energy are viewed in the light of one-hundred years of subsequent flow research. Attempts to use Reynolds energy-balance method to calculate the lower critical Reynolds number for pipe and channel flows is reviewed. The modern use of turbulence-energy methods for boundary layer transition modelling is discussed, and a current European Working Group effort to evaluate and develop such methods is described. The possibility of applying these methods to calculate transition in pipe, channel and sink flows is demonstrated using a one-equation, q-L, turbulence model. Recent work using the equation for the kinetic energy of mean motion to gain understanding of loss production mechanisms in three-dimensional turbulent flows is also discussed.
Heat Transfer Enhancement Within a Turbine Blade Cooling Passage Using Ribs and Combinations of Ribs With Film Cooling Holes
Authors: Shen J. R. , Wang Z. , Ireland P. T. , Jones T. V. , Byerley A. R.
Published: February 2015

A transient heat transfer method which uses liquid crystals has been applied to a scale model of a turbine rotor blade passage. Detailed contours of local heat transfer coefficient are presented for the passage in which the heat transfer to one wall was enhanced firstly by ribs and then with ribs combined with holes. The hole geometry and experimental dimensionless flow rates were representative of those occurring at the entrance to engine film cooling holes. The results for the ribbed passage are compared to established correlations for developed flow. Qualitative surface shear stress distributions were determined with liquid crystals. The complex distributions of heat transfer coefficient are discussed in the light of the interpreted flow field.
Effects of Surface Riblets and Free-Stream Turbulence on Heat Transfer in a Linear Turbine Cascade
Authors: Maciejewski Paul K. , Rivir Richard B.
Published: February 2015

The present study is an experimental investigation of the effects of free-stream turbulence and surface riblets on the heat transfer rate in a linear turbine cascade. The primary goal of the study is to determine if surface riblets will reduce the average heat transfer rate in a cascade in the absence and in the presence of free-stream turbulence. A smooth, airfoil shaped, constant temperature, heat transfer test surface was inserted into a linear cascade facility where heat transfer tests were run at three levels of Reynolds number and two levels of free-stream turbulence. The heat transfer test surface was then removed from the facility so that riblets could be engraved on its surface. The newly ribleted heat transfer surface was then re-inserted into the cascade facility, where a second set of heat transfer tests were run at the same set of conditions used during the testing of the test surface while it was smooth. The test results indicate that, under certain conditions, surface riblets reduce the average heat transfer rate in the cascade by 7%.
A Dry Low NOx Combustor for the MS3002 Regenerative Gas Turbine
Authors: Maughan James R. , Luts Andrew , Bautista Paul J.
Published: February 2015

A dry low NOx combustion system is being developed for the MS3002J regenerative cycle, mechanical drive gas turbine, which is used extensively for pumping applications in natural gas pipelines. The combustion system is based on the DLN combustor developed for the MS6001B simple cycle, heavy duty gas turbine. Results are presented for full scale, single combustor screening tests at reduced pressure. As this is the first regenerative cycle application of DLN technology, most of the screening effort focused on understanding and quantifying the effects of high inlet temperature on combustor emissions and operability. At constant combustor exit temperature, NOx emissions in diffusion modes of operation increased as the inlet temperature was increased from 650 to 950 F, corresponding to the MS6001B simple cycle and MS3002J regenerative cycle respectively. In premixed mode, however, NOx emissions decreased significantly as inlet temperature was increased. This effect is attributed to the decrease in combustor burning zone temperature required to maintain a constant exit temperature as the dilution air temperature increases. Flashback and autoignition were not seen, and dynamic pressure activity diminished as inlet temperature was increased. CO emissions were low due to the increased reaction zone volume afforded by the MS3002 combustion system length.
Development of a Catalytic Combustor for Industrial Gas Turbines
Authors: Cowell Luke H. , Larkin Matthew P.
Published: February 2015

A catalytic combustion system for advanced industrial gas turbines is under long tern development employing recent advances in catalyst and materials technologies. Catalytic combustion is a proven means of burning fuel with single digit NOx emissions levels. However, this technology has yet to be considered for production in an industrial gas turbine for a number of reasons including: limited catalyst durability, demonstration of a system that can operate over all loads and ambient conditions, and market and cost factors. The catalytic combustion system will require extensive modifications to production gas turbines including fuel staging and variable geometry. The combustion system is composed of five elements: a preheat combustor, premixer, catalyst bed, part load injector and post-catalyst combustor. The preheat combustor operates in a lean premixed mode and is used to elevate catalyst inlet air and fuel to operating temperature. The premixer combines fuel and air into a uniform mixture before entering the catalyst. The catalyst bed initiates the fuel-air reactions, elevating the mixture temperature and partially oxidizing the fuel. The part load injector is a lean premixed combustor system that provides fuel and air to the post-catalyst combustor. The post-catalyst combustor is the volume downstream of the catalyst bed where the combustion reactions are completed. At part load conditions a conventional flame bums in this zone. Combustion testing is on-going in a subscale rig to optimize the system and define operating limits. Short duration rig testing has been completed to 9 atmospheres pressure with stable catalytic combustion and NOx emissions down to the 5 ppmv level. Testing was intended to prove-out design elements at representative full load engine conditions. Subscale combustion testing is planned to document performance at part-load conditions. Preliminary full-scale engine design studies are underway.
An N-S Simulation of Stall Cell Behavior in a 2-D Compressor Rotor-Stator System at Various Loads
Authors: Outa Eisuke , Kato Dai , Chiba Kaoru
Published: February 2015

Stall characteristics and stall cell behavior in a linear cascades system of a single stage axial compressor are presented by applying a numerical analysis of compressible N-S equations. The system consists of a rotor and a stator, where flow is assumed to be periodic over six blades and ten vanes respectively. Although the number of blades and vanes per period is much less than that in the real-rig, and the analysis is conducted in a laminar viscosity mode, computed stage performance from normal operation to deep stall agrees fairly well with experimental data. In deep stall, rotor cell propagates in linkage with stator cell at a computed speed of 65 % of the rotor speed. This speed is considerably close to the measured value of 55 %. Stall cell propagation is discussed on flow patterns showing stall development, stall induction in the follower blade and interaction between the rotor and stator.
Modal Analysis of Blades With Densely Distributed Small Holes
Authors: Zhang Jin , Wang Zhen-Hua , Dong Ben-Hua
Published: February 2015

At present, when numerical methods are used to analyze the dynamic characteristics of blades with densely distributed small holes, it is difficult to consider the influence of small holes accurately. A new method is presented regarding air-cooled turbine rotor blades of gas turbine engines. To investigate the topic, a series of experimental rules are simulated effectively by theoretical formulae. The method is developed by combining the experimental results and finite element analysis. To include the effects of small holes on dynamic behaviors of blades, the equivalent concept is employed. In a generalized eigen-equation, the modified stiffness matrix and mass matrix are used to perform an accurate modal analysis of the blades. When making comparison between the analytical results obtained by using the method of this paper and the experimental data, a good agreement is seen. Accuracy, reliability, and practicality of the method presented in this paper are verified.
The Influence of Various Exhaust Geometrical Parameters on the Effectiveness of an Aero-Engine Intake Thermal Anti-Icing System
Authors: Riley S. J. , James E. H.
Published: February 2015

Anti-icing air from the internal nose cowl regions of aircraft engines exits via an exhaust slot to join the engine intake air upstream of the compressor. It is important that this still hot air be used efficiently downstream of the exhaust slot to effect heating of the downstream surface (acoustic liner) to facilitate the prevention of ice build-up at this point. To this end, various exhaust slot geometry designs have been investigated in an experimental study to provide guidelines to assist in this aim. The most significant variables were found to be assembly length, slot depth, exit plane width and exhaust angle. Surface heating effectiveness does not appear to be affected by “blowing ratio” differences between exhaust geometries. Equations are derived and suggested to predict the skin temperature decay downstream of the exhaust slot for a range of “blowing ratios” but the benefits in anti-icing performance must be considered ultimately against weight, cost, reliability, maintenance factors and in-service experience.
HRSG Design for Optimum Combined Cycle Performance
Authors: v. Manen A.
Published: February 2015

This paper covers the design of heat recovery steam generators (HRSG).

The design of the HRSG plays an important role in overall design of a combined cycle unit. The primary focus of the paper is the influence of the boiler on the total efficiency of the combined cycle.
Room-Temperature Strength of Sintered Silicon Nitride Subjected to High-Temperature Creep Loading
Authors: Nakasuji Yoshizumi , Iwasaki Hiroyuki , Sakai Hiroaki
Published: February 2015

Room-temperature strength was evaluated using sintered silicon nitride crept specimens. Creep tests were performed using 4-point bending loading at 1400°C in air. The bending creep tests applied stresses from 100 to 400 MPa for 10−1 to 3×103 hours. For applied stress over 200 MPa, the room-temperature strength of the crept specimen had two stages. In the first stage the strength degraded slowly, and in the second stage the strength degraded rapidly. In the first stage, oxidation caused the strength degradation, since the degradation was similar for the different applied stresses. In the second stage, large creep deformation mainly caused the strength degradation. Early in the stage, creep induced matrix and boundary damage under the oxidation layer caused the degradation. At the end of the stage, cracks induced by creep caused the degradation.
Development of an Experimental LPP Gas Turbine Combustor
Authors: Johansson Patrik , Sjunnesson Anders , Olovsson Stefan
Published: February 2015

The design of a generic experimental LPP-combustor (Lean Premixed Prevaporized) is described. The combustor was tested at inlet pressures between 3 and 7 bar and with an inlet temperature between 500 K and 700 K. Tests were run with Diesel No.2 and Jet A-1 fuels comparing emissions of CO and NOx. The tests showed low NOx and CO values for a range of conditions although difficulties of using the LPP-technique close to the final boiling point of the fuel were encountered. To increase the understanding of the flow situation inside the combustor, numerical simulations using a large eddy simulation code was also performed. The main interest in the calculations was the evaporation process of the liquid fuel.
Hydrodynamic Torque Converters in Mechanical Transmission Systems: Methods and Analysis
Authors: Hedman Anders
Published: February 2015

Methods for analysis of general mechanical transmission systems with a hydrodynamic torque converter (HTC) are presented. The methods are adapted for computer calculations. The properties of the HTC must be known, either explicitly as speed and torque characteristics, or implicitly as internal geometry (blade angles, etc.).

Linear relationships between the torques and between the speeds of the shafts of the transmission system (except the HTC) are easily formulated. The HTC has coupled, non-linear, relationships for torques and speeds. Different ways of including these non-linear equations are presented. This can be implemented in a computer program.

Solving the equation system yields the torque and speed of each shaft of the transmission system. Power losses can be handled.
A Colour Image Processing System for Transient Liquid Crystal Heat Transfer Experiments
Authors: Wang Zuolan , Ireland Peter T. , Jones Terry V. , Davenport Robert
Published: February 2015

A colour image processing system for liquid crystal heat transfer experiment has been developed. The system is capable of digitizing and processing the complete liquid crystal surface colour (hue) change history in a transient test and, together with a calibration, can give the complete history of surface temperature over a full surface. Two methods for automatically processing the hue history to give heat transfer coefficient distributions are presented. Both methods raise the accuracy of the transient technique above other approaches by using the redundancy inherent in the multiple surface temperature measurements. The first regression approach applied to the determination of both h and Tgas is reported. The uncertainty in all measurements has been quantified and examples of applications of both techniques given.
Vortical Gust Response of a Low Solidity Vane Row Including Steady Loading and Dynamic Stall Effects
Authors: Henderson Gregory H. , Fleeter Sanford
Published: February 2015

The effects of high steady loading and separated flow on the unsteady aerodynamic response of turbomachine blade rows are experimentally investigated. This is accomplished utilizing a unique single stage turbomachine research facility in which the flow is not generated by the blading but rather by an additional fan. Thus, for a particular stator incidence angle, the steady or mean stator aerodynamic performance were determined in a completely steady flow with no rotor and also with unsteady flow generated by a rotor composed of perforated plates at the same mean operating condition, thereby identifying the stator vane row dynamic stall conditions. The unsteady aerodynamic response of the very low solidity stator vane row is then investigated over a range of incidence angle values, including attached and separated flows with dynamic stall.
Aircraft Crash Caused by Stress Corrosion Cracking
Authors: Kolkman H. J. , Kool G. A. , Wanhill R. J. H.
Published: February 2015

An aircraft crash in the Netherlands was caused by disintegration of a jet engine. Fractography showed that the chain of events started with stress corrosion cracking (SCC) of a pin attached to a lever arm of the compressor variable vane system. Such a lever arm-pin assembly costs only a few dollars. Investigation of hundreds of pins from the accident and a number of identical engines revealed that this was not an isolated case. Many pins exhibited various amounts of SCC. The failed pin in the accident engine happened to be the first fractured one.

SCC requires the simultaneous presence of tensile stress, a corrosive environment and a susceptible material. In this case the stress was a residual stress arising from the production method. There was a clear correlation between the presence of salt deposits on the levers and SCC of the pins. It was shown that these deposits were able to reach the internal space between the pin and lever arm, thereby initiating SCC in this space. The corrosive environment in Western Europe explains why the problem manifested itself in the Netherlands at a relatively early stage in engine life. The main point is, however, that the manufacturer selected an SCC-prone material in the design stage. The solution has been to change the pin material.
Detailed Measurements on a Modern Combustor Dump Diffuser System
Authors: Carrotte J. F. , Bailey D. W. , Frodsham C. W.
Published: February 2015

An experimental investigation has been carried out to determine the flow characteristics and aerodynamic performance of a modern gas turbine combustor dump diffuser. The system comprised of a straight walled pre-diffuser, of area ratio 1.35, which projected into a dump cavity where the flow divided to pass either into the flame tube or surrounding feed annuli. In addition, a limited amount of air was removed to simulate flow used for turbine cooling. The flame tube was relatively deep, having a radial depth 5.5 times that of the passage height at pre-diffuser inlet, and incorporated burner feed arms, cowl head porosity, cooling rings and primary ports. Representative inlet conditions to the diffuser system were generated by a single stage axial flow compressor.

Results are presented for the datum configuration, and for a further three geometries in which the distance between pre-diffuser exit and the head of the flame tube (ie. dump gap) was reduced. Relatively high values of stagnation pressure loss were indicated, with further significant increases occurring at smaller dump gaps. These high losses, which suggest a correlation with other published data, are due to the relatively deep flame tube and short diffuser length. Furthermore, the results also focus attention on how the presence of a small degree of diffuser inlet swirl, typical of that which may be found within a gas turbine engine, can result in large swirl angles being generated further downstream around the flame tube. This is particularly true for flow passing to the inner annulus.
FEM Model to Support Electro Chemical Drilling of Turbulated Cooling Holes
Authors: van Dijk M. H. H. , Verhappen B. T. M. , Jansen J. K. M. , Noot M. J.
Published: February 2015

Airfoils of industrial gasturbines are provided with longitudinal cooling holes. The cooling efficiency of these holes may be improved by introducing multiple ribs, so-called turbulators. The Electro Chemical Drilling process is used to drill longitudinal cooling holes with or without turbulators in casted as well as in forged airfoils. Turbulated cooling holes are drilled by varying process parameters during drilling. A FEM model is developed to determine the effect of parameter variations on the shape of the turbulators. The model can also be used to study the effect of fluctuations of parameters on the quality of straight and turbulated holes. The feasibility of the model is demonstrated by comparing calculated and experimental results of a step-wise variation of the cathode voltage.
Measurements of Local Heat Transfer Coefficient Over the Full Surface of a Bank of Pedestals With Fillet Radii
Authors: Wang Zuolan , Ireland Peter , Jones Terry , Kohler S. Toby
Published: February 2015

Complete distributions of local heat transfer coefficient have been measured over the full surface of a pedestal bank at a number of Reynolds numbers. The transient heat transfer method with thermochromic liquid crystals used as the surface thermometer was used to obtain the data. The pedestal geometry included fillet radii representative of those used in engine blade cooling passages. The heat transfer coefficient distributions are compared to previously reported local measurements made on a bank of plain cylinders. Averaged values based on the local mixed bulk gas temperature are compared to established correlations. The distributions of local heat transfer coefficient show a remarkable periodicity when based on a local temperature. These patterns are discussed in terms of the interpreted flow field. Measurements of pressure drop are also reported and, for a range of engine representative Reynolds numbers, agree with an existing correlation for prismatic pedestals.
Technical and Economic Evaluation of Nominal 280 MW Compressed Air Energy Storage Plant in Salt Dome
Authors: Morrison Alex , Mehta Bhupen , Lyons J. W. , Gnaedig Gregor
Published: February 2015

This paper summarizes the results of the technical and economic data of nominal 280 MW Compressed Air Energy Storage Plants (CAES) using caverns in salt domes located in southeastern parts of Mississippi for intermediate duty generation of 1,000 hours per year and peaking duty generation of 750 hours per year. The plants are assumed to operate 90% time on Natural Gas and 10% of the time on No. 2 distillate. A weekly cycle of 10 hours of generation and 12 hours of charging daily with 15 hours of weekend charging was the basis for the study. The study includes conceptual layout, optimization, detailed cost analyses, reliability and operation and maintenance of the Compressed Air Energy storage plant. The objective of the study is low capital cost of the CAES plant and optimum performance.
Development of Ceramic Rotor Blade for Power Generating Gas Turbine
Authors: Teramae Tetsuo , Furuse Yutaka , Wada Katsuo , Machida Takashi
Published: February 2015

To cope with the increasing demand of electric power, many research and development programs have been performed in the field of electric power industry. Among them, the application of highly thermal resistive ceramics to hot parts of the gas turbines is one of the most promising ways to raise the thermal efficiency of the gas turbine, and several projects have been executed in the U.S.A., Europe and Japan.

Tokyo Electric Power Co., Inc. (TEPCO) also has been conducting a research project to apply ceramic components to hot parts of a 20MW class gas turbine with a turbine inlet temperature of 1300C. In this project. TEPCO and Hitachi have been conducting the cooperative research work to develop a first stage ceramic rotor blade.

After several design modifications, it was decided to select ceramic blades attached directly to a metal rotor disc, and to insert metal pads between the dovetail of the ceramic blade and metal disc to convey the centrifugal force produced by the blade smoothly to the metal disc.

The strength of this ceramic blade has been verified by a series of experiments such as tensile tests, room temperature spin tests, thermal loading tests, and high temperature spin tests using a high temperature gas turbine development unit (HTDU).

In addition, the reliability of the ceramic blade under design and test conditions has been analyzed by a computer program GFICES (Gas turbine - Fine Ceramics Evaluation System) which was developed on the basis of statistical strength theory using two parameter Weibull probability distribution.

These experiments and analyses demonstrate the integrity of the developed ceramic rotor blade.
Film Cooling With Compound Angle Holes: Adiabatic Effectiveness
Authors: Schmidt Donald L. , Sen Basav , Bogard David G.
Published: February 2015

Film cooling effectiveness was studied experimentally in a flat plate test facility with zero pressure gradient using a single row of inclined holes which injected high density, cryogenically cooled air. Round holes and holes with a diffusing expanded exit were directed laterally away from the freestream direction with a compound angle of 60°. Comparisons were made with a baseline case of round holes aligned with the freestream. The effects of doubling the hole spacing to six hole diameters for each geometry were also examined. Experiments were performed at a density ratio of 1.6 with a range of blowing ratios from 0.5 to 2.5 and momentum flux ratios from 0.16 to 3.9. Lateral distributions of adiabatic effectiveness results were determined at streamwise distances from 3 D to 15 D downstream of the injection holes. All hole geometries had similar maximum spatially averaged effectiveness at a low momentum flux ratio of I = 0.25, but the round and expanded exit holes with compound angle had significantly greater effectiveness at larger momentum flux ratios. The compound angle holes with expanded exits had a much improved lateral distribution of coolant near the hole for all momentum flux ratios.