bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Numerical Study of the Interaction of a Transonic Compressor Rotor Overtip Leakage Vortex With the Following Stator Blade Row
Authors: Dawes W. N. 
Published: February 2015

This paper presents a numerical simulation of the unsteady flow in a transonic compressor stage. The simulations were performed using an unstructured mesh, 3D Navier-Stokes solver with a sliding interface between the mesh blocks containing the rotor and stator blades to permit a time-resolved calculation. The focus in the simulation is the endwall flow, its contrast with the mid-span flow and, in particular, the interaction of the rotor overtip leakage flow with the downstream stator.
The endwall region of both the rotors and the stators was predicted to be proportionally responsible for much more loss production than the mid-span sections of the blading. Unsteady effects were predicted to be responsible for rather more of the total loss production in the rotors than in the stators but the unsteady loss production in the rotors did not seem to be associated with the endwall flow but rather occurred over the bulk of the blade span caused by unsteady shock motion. By contrast, the rotor overtip leakage flow was shown to cause a considerable degradation of the stator performance near the casing. In the stators nearly a third of the loss production near the endwall was predicted to be directly due to unsteady effects associated with the rotor vortex interaction and a number of individual physical loss generating mechanisms were identified.
The Influence of Secondary Flows Near the Endwall and Boundary Layer Disturbance on Convective Transport From a Turbine Blade
Authors: Goldstein R. J. , Wang H. P. , Jabbari M. Y. 
Published: February 2015

A naphthalene sublimation technique is used to investigate convective transport from a simulated turbine blade in a stationary linear cascade. In some of the tests undertaken a trip wire is stretched along the span of the blade near the leading edge. The disturbance produced by tripping the boundary layers on the blade near the leading edge causes early boundary layer transition, creates high mass transfer rate on the pressure side and in the laminar flow region on the suction side, but lowers the transfer rate in the turbulent flow region on the suction side. Comparison is made with other heat and mass transfer studies in the two dimensional region far from the endwall and good agreement is found.
Near the endwall, flow visualization indicates a strong secondary flow pattern. The impact of vortices initiated near the endwall on the laminar-turbulent transition extends three dimensional effects to about 0.8 chord lengths on the suction side and to about 0.2 chord lengths on the pressure side away from the endwall. The effect of the passage vortex and the new vortex induced by the passage vortex on mass transfer is clearly seen and can be traced along the suction surface of the blade. Close to the endwall the highest mass transfer rate on the suction surface is not found near the leading edge. It occurs at about 27% of the curvilinear distance from the stagnation line to the trailing edge where a strong main flow and the secondary passage flow from the pressure side of the adjacent blade interact. The influences of some small but very intense corner vortices and the passage vortex on mass transfer are also observed on both surfaces of the blade.
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.
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.
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.
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.
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.
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.
Ceramic Stationary Gas Turbine Development Program: First Annual Summary
Authors: van Roode Mark , Brentnall William D. , Norton Paul F. , Boyd Gary L. 
Published: February 2015

A program is being performed under the sponsorship of the United States Department of Energy, Office of Industrial Technology, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of hot section components with ceramic parts. It is envisioned that the successful demonstration of ceramic gas turbine technology, and the systematic incorporation of ceramics in existing and future gas turbines will enable more efficient engine operation, resulting in significant fuel savings, increased output power, and reduced emissions.
The engine selected for the program, the Centaur 50 (formerly named Centaur ‘H’) will be retrofitted with first stage ceramic blades, first stage ceramic nozzles, and a ceramic combustor liner. The engine hot section is being redesigned to adapt the ceramic parts to the existing metallic support structure.
The work in Phase 1 of the program involved concept and preliminary engine and component design, ceramic materials selection, technical and economic evaluation, and concept assessment. A detailed work plan was developed for Phases II and III of the program. The work in Phase II addresses detailed engine and component design, and ceramic specimen and component procurement and testing. Ceramic blades, nozzles, and combustor liners will be tested in subscale rigs and in a gasifier rig which is a modified Centaur 50 engine. The Phase II effort also involves long term testing of ceramics, development of appropriate nondestructive technologies for part evaluation, and component life prediction. Phase III of the program focuses on a 4,000 hour engine test at a cogeneration site.
This paper summarizes the progress on the program through the end of 1993.
Theoretical and Experimental Investigation of Circumferential Grooved Casing/Hub Treatment
Authors: Du Zhaohui , Liu Zhiwei 
Published: February 2015

In this paper the 3-dimensional viscous numerical calculation is applied to explain the mechanism of extending stability of circumferential grooved casing and hub treatments. A new index which can quantitatively evaluate the ability to extend stability of circumferential grooved casing and hub treatments is proposed with flux of gas through the treatment grooves. The influences of the geometric parameters on improving stall margin are discussed. The conclusions are the same as those of experiments.
A circumferential grooved hub treatment is designed and tested beneath the stator blade row in a single stage axial flow compressor. The upstream and downstream 3-dimension flowfields are measured carefully in optimum operation condition and near stall margin condition by a combined three-hole probe and a mirco-five-hole probe which has 1.5mm diameter. It is shown that stall margin can be improved not only for the single stage compressor, but also for the rotor. Through a lot of experimental investigations and theoretical analyses, the mechanism of extending stability of circumferential grooved casing and hub treatments are systematic and comprehensive explained.
On the Transport of Spatial Fluctuation Correlations in a Turbine Stator
Authors: Perrin G. , Leboeuf F. 
Published: February 2015

When averaging the Navier-Stokes or Euler equations in the circumferential direction of a turbomachine, some so-called “spatial fluctuation terms” appear in the averaged conservation equations. We give the transport equations for these kinematic spatial fluctuation correlations. We evaluate the various terms in these equations, using the results of a three-dimensional Navier-Stokes computation. The test case is a highly loaded subsonic turbine stator.
We discuss the magnitudes of the various terms. It is shown that blade force terms and diffusion terms have dominant effects, as respect to the production by the averaged field and the shear stress terms. The dissipation of the fluctuation kinetic energy occurs mainly in the passage vortex area, and in the blade wake.