bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Use of Cyclic Variations in Strut Stagger to Reduce Coupled Blade-Vane-Strut-Pylon Interaction and System Losses
Authors: Parry A. B. , Bailey R. H. 
Published: December 2014

In this paper we extend previous work on fan-vane-pylon interaction to account for an additional row of struts between the vanes and the pylon(s). These struts have two effects: they generate their own potential field in addition to that generated by the pylon(s); and they also act to magnify the pylon generated field. The combined effect of the struts and pylon is to generate a nonuniform potential field which is much greater than that generated by the pylon(s) in isolation — and, indeed, much greater than that obtained by simple superposition of the pylon-alone and strut-alone fields — resulting in increased fan forcing and vane losses. We consider two engine configurations: one with struts positioned ahead of a pylon; and one with the struts integrated with two (unequal) pylons. Predictions are generated in two dimensions by using an inviscid CFD scheme for the struts and pylons, linked to a tandem actuator disc model to represent the fan and the outlet guide vanes (OGVs). The predictions are validated by comparison with some vane leading-edge static pressure measurements taken from a full scale engine. The OGV loss in the distorted flow is predicted by judicious use of OGV loss loops for uniform flow.
The predicted results for the first engine with separate struts and pylon show the magnification effect of the struts, and the increase in sectional losses due to the strut and pylon induced circumferential flow variations. It is shown that (at least) half of the increase in sectional losses can be recovered by cyclically staggering the struts with the strut stagger angles determined from a separate pylon-alone calculation. For the second engine with integrated struts and pylons the predictions show that there are even greater increases in the potential field transmitted through the vanes and in the sectional losses, which are two thirds higher than those for the OGVs in uniform flow. However, the predicted increase in OGV losses is reduced to only a fifth with a particular restaggered-strut design; moreover, the loss in the restaggered strut case is lower than that obtained for the isolated pylons with no integrated struts. The results also show that in determining the appropriate strut restagger angles it is important to take account of the back effect of the fan and OGVs.
Effect of a Mismatch Between the Buttons of Variable Stator Vanes and the Flowpath in a Highly Loaded Transonic Compressor Stage
Authors: Escuret J. F. , Veysseyre Ph. , Villain M. , Savarese S. , Bois G. , Navière H. 
Published: December 2014

This paper presents both experimental and numerical results demonstrating the dramatic effect of a particular geometric discontinuity on the flow within a highly-loaded single-stage transonic compressor. This compressor features cantilevered variable-stagger stator vanes (VSV) with buttons at the outer radius partially standing out in the annulus, by a value of about 0.3 mm which amounts to 0.5% of vane height.
The first tests of this compressor revealed a very large corner flow separation at the stator outer radius. This feature could not be reproduced by steady 3D Navier-Stokes computations of the stator flow field with a smooth flowpath. However, using a simple numerical approach to account for the actual geometric discontinuity of the annulus, the computation then showed flow trends similar to that of the experiment. Also, a detailed analysis of the computed flow field indicated that the flow turning (both radial and tangential) due to the button blockage contributed toward strengthening the effect of secondary flows. Subsequently, after the button geometry was corrected to match the flowpath, further tests confirmed a much more satisfactory flow behaviour within the stator vanes leading to a one point improvement in compressor isentropic efficiency.
This study leads to the conclusion that ensuring a smooth flowpath can be critically important for the high stage leadings characteristic of advanced military applications. Moreover, the predictive value of 3D Navier-Stokes computations for the simulation of technological effects, such as VSV buttons / flowpath mismatch, is clearly demonstrated.
The Unsteady Pressure Field Over a Turbine Blade Surface: Visualisation and Interpretation of Experimental Data
Authors: Moss Roger W. , Ainsworth Roger W. , Sheldrake Colin D. , Miller Robert 
Published: December 2014

The unsteady static pressure field over a turbine rotor has been measured in the Oxford Rotor Facility using 78 flush-mounted miniature pressure transducers. This extensive surface coverage allows ensemble-averaged data to be displayed as an animated image. At the mid-height plane the fluctuations are well predicted using the UNSFLO 2-D unsteady code: away from mid-height the data shows large fluctuations.
12 transducers mounted on the blade leading edge show the relative total pressure field entering the blade row; these plus area traverse measurements at rotor exit are used to interpret the surface flow features. Rotor-mounted hot wires show large variations in blade incidence during the wake-passing cycle and allow conversion of blade-relative data into the absolute frame. Large pressure fluctuations in the root region may be explained in terms of a loss core associated with the NGV wake.
Development of a High Pressure Ratio Centrifugal Compressor for 300kW-Class Ceramic Gas Turbine
Authors: Sakai T. , Tohbe Y. , Fujii T. , Tatsumi T. 
Published: December 2014

Research and development of ceramic gas turbines (CGT), which is promoted by the Japanese Ministry of International Trade and Industry (MITI), was started in 1988. The target of the CGT project is development of a 300kW-class ceramic gas turbine with a 42 % thermal efficiency and a turbine inlet temperature (TIT) of 1350°C. Two types of CGT engines are developed in this project. One of the CGT engines, which is called CGT302, is a recuperated two-shaft gas turbine with a compressor, a gas-generator turbine, and a power turbine for cogeneration. In this paper, we describe the research and development of a compressor for the CGT302.
Specification of this compressor is 0.89 kg/sec air flow rate and 8:1 pressure ratio. The intermediary target efficiency is 78% and the final target efficiency is 82%, which is the highest level in email centrifugal compressors like this one.
We measured impeller inlet and exit flow distribution using three-hole yaw probes which were traversed from the shroud to the hub. Based on the measurement of the impeller exit flow, diffusers with a leading edge angle distribution adjusted to the inflow angle were designed and manufactured. Using this diffuser, we were able to attain a high efficiency (8:1 pressure ratio and 78% adiabatic efficiency).
A Unique Application of Gas Turbine Engines in a High Speed Marine Vessel
Authors: Higgins Timothy M. , Freuler Richard J. , Blount Donald L. , Thames Janna M. 
Published: December 2014

A high speed marine vessel, powered by three LM1600 gas turbine engines, is being converted from a high speed racing vessel to a luxury yacht. The vessel’s geometry is being modified to include a centerline walkway to provide passage to the aft deck.
A scale model of the vessel’s air intake system was tested to determine if the modified design complied with performance specifications determined by the engine manufacturers. It was found that the total pressure loss and distortion of the engine inlet air was within performance limits. However, the swirl angles of the inlet air for the center engine exceeded limits locally.
System modifications were devised and tested to improve the quality of intake air. The modifications decreased swirl angle magnitudes to generally within engine manufacturer’s specifications. Additionally, the expansion of spaces devoted to the other ship systems did not significantly impair the aerodynamic performance of the air intake systems.
Thermal Spray Manufacturing Issues in Coating IGT Hot Section Components
Authors: Sahoo P. , Carr T. , Martin R. , Dinh F. 
Published: December 2014

The desire to improve the performance and efficiency of gas turbine engines has led to higher operating temperatures in the turbine sections of the engine. Present materials and materials under development for hot section turbine blades and vanes are not inherently resistant to hot corrosion, and therefore require protective coatings. In the past two decades this has led to increased use of thermally sprayed MCrAlY coatings, both as stand-alone overlay and as a bond coat for thermal barrier coatings.
This paper reviews the issues involved in thermally sprayed MCrAlY and TB coatings onto hot section blades and vanes of industrial gas turbines. The generation of a specification for coating acceptance and its practical implications are discussed. The issues in applying such coatings will be discussed, along with references to manufacturing issues on the shop floor. The difficulties inherent in applying a line-of-sight coating to complex geometric shapes will be discussed, with particular reference to robotics spraying. The utility of using a design-of-experiment approach to satisfy the user will be reviewed. The testing, evaluation, and performance characteristics of typical coatings are discussed.
Start Up Analysis of a H2-O2 Fired Gas Turbine Cycle
Authors: Funatsu T. , Fukuda M. , Dohzono Y. 
Published: December 2014

The new thermodynamic cycle using hydrogen energy is now under investigation by many engineers. The Japanese World Energy Network research program is also hydrogen technology development program. One of the target of the program is to develop the high thermal efficiency power plant without emissions. The H2-O2 fired gas turbine is the key technology of the project and the new RANKINE cycle is suggested as one of the most effective cycle.
The new RANKINE cycle is based on the direct steam expansion cycle and the performance calculation has been examined to find the optimal operating point. For the cycle development, further investigations of the component development, the operational ability, and the cost competitiveness are important. Among these investigations, this paper reports the operational ability, especially the start up performance.
In this analysis, the algorithm and flow line for start up is developed. And the investigation finds that the new RANKINE cycle has the good possibility for the practical use.
Wake Decay: Effect of Freestream Swirl
Authors: Brookfield J. M. , Waitz I. A. , Sell J. 
Published: December 2014

A study of the effects of freestream swirl on the decay characteristics of wakes shed from a rotating blade row is presented. The freestream swirl behind the rotor causes the wakes to skew tangentially, stretching the wakes as they are convected from the rotor to the stator. The effect of stretching on wake decay is illustrated using a simplified two-dimensional model. The model is described and the results are compared to 1) measurements from a two-dimensional cascade facility where no stretching or skewing of the wakes occurs, 2) solutions obtained using a three-dimensional, Reynolds-averaged Navier-Stokes solver, and 3) experimental wake measurements taken behind a low hub-to-tip ratio fan.
For typical fan geometries with hub-to-tip ratios of approximately 0.5 and rotor-stator spacings of one to two rotor chord lengths, the wake can be stretched by over 50 percent. The stretching increases the mixing rate which leads to a reduction in the mean wake velocity deficit of approximately thirty percent and a widening of the wake of about fifteen percent. These effects account for much of the difference seen between cascade wake measurements and those taken behind rotating fan blade rows. It is therefore important to include such effects when using cascade data for prediction of fluid mechanic, acoustic, or structural phenomena associated with fan wakes. Finally, the study also suggests a potential for small (< 3 dB) reductions in wake-stator interaction noise through tailoring the fan loading distribution to produce particular span wise wake decay characteristics.
An Experimental Study of Steam Injection in an Aeroderivative Gas Turbine
Authors: Meyer Jean-Louis , Grienche Guy 
Published: December 2014

The injection of steam into a gas turbine allows a reduction in nitrogen oxide (NOx) emissions and an increase in power and efficiency. In this way, and due especially to their lower investment costs, massive steam injection cycles could represent an interesting concept for intermediate-load power plants.
When EDF and TURBOMECA jointly decided to carry out an experimental study of the consequences of steam injection into a gas turbine, two test phases were defined: firstly, a limited steam injection phase to assess the effect of steam on combustion, and secondly, a massive injection phase to assess the behavior and the performance capabilities of the machine. This second phase also aimed at identifying the critical points likely to appear when adapting a heavy-duty gas turbine to massive steam injection. This publication summarizes the main results of these two phases of tests.
Performance Assessment of Steam Injection Gas Turbine With Inlet Air Cooling
Authors: Bartolini Carlo M. , Salvi Danilo 
Published: December 2014

The steam generated through the use of waste heat recovered from a steam injection gas turbine generally exceeds the maximum mass of steam which can be injected into steam injection gas turbine. The ratio between the steam and air flowing into the engine is not more than 10–15%, as an increase in the pressure ratio can cause the compressor to stall. Naturally, the surplus steam can be utilized for a variety of alternative applications.
During the warmer months, the ambient temperature increases and results in reduced thermal efficiency and electrical capacity. An inlet air cooling system for the compressor on a steam injection gas turbine would increase the rating and efficiency of power plants which use this type of equipment. In order to improve the performance of steam injection gas turbines, the authors investigated the option of cooling the intake air to the compressor by harnessing the thermal energy not used to produce the maximum quantity of steam that can be injected into the engine. This alternative use of waste energy makes it possible to reach maximum efficiency in terms of waste recovery. This study examined absorption refrigeration technology, which is one of the various systems adopted to increase efficiency and power rating. The system itself consists of a steam injection gas turbine and a heat recovery and absorption unit, while a computer model was utilized to evaluate the off design performance of the system. The input data required for the model were the following: an operating point, the turbine and compressor curves, the heat recovery and chiller specifications. The performance of an Allison 501 KH steam injection gas plant was analyzed by taking into consideration representative ambient temperature and humidity ranges, the optimal location of the chiller in light of all the factors involved, and which of three possible air cooling systems was the most economically suitable. In order to verify the technical feasibility of the hypothetical model, an economic study was performed on the costs for upgrading the existing steam injection gas cogeneration unit. The results indicate that the estimated pay back period for the project would be four years. In light of these findings, there are clear technical advantages to using gas turbine cogeneration with absorption air cooling in terms of investment.
A Projection of Advancements in Aeroderivative Gas Turbine Technology for the Next Two Decades (With Specific Emphasis on Off-Shore Applications)
Authors: Spector R. B. , Patt R. F. 
Published: December 2014

This paper presents the authors’ perspective regarding the growth of gas turbine technology as applied to the industrial market for the next two decades. Although emphasis is placed on off-shore (platform and floating production) applications, the effects of the advance in technology of gas turbines for land based operations is included. Past trends in the advancement of basic gas turbine technology are utilized as the basis to establish this forecast.
An introduction and a description of the Air Bottoming Cycle, the Intercooled Gas Turbine Cycle, and a hybrid gas turbine combining aeroderivative and heavy frame design are also included.
Unique Reverse and Maneuvering Features of the AOE-6 Reverse Reduction Gear
Authors: Zekas B. Michael , Schultz Andrew N. 
Published: December 2014

A unique Reverse Reduction Gear system is being utilized on the U.S. NAVY AOE-6 Class ships. The AOE-6 is the first of (4) Fast Combat Support ships being built by National Steel and Shipbuilding Company (NASSCO) in San Diego, Ca.
The principal characteristics of the AOE-6 Class ships are as follows:
Length Overall - 753 Feet 8.5 Inches
Beam - 107 Feet
Mean Draft (Full Load) - 37 Feet 10 Inches
Displacement - 48,500 Long Tons
Total Shaft Horsepower - 100,000 HP
The ships are powered by (4) General Electric LM2500 gas turbine engines, driving thru (2) main reduction gears manufactured by the Cincinnati Gear Co., to (2) shafts fitted with fixed pitch propellers. Each main reduction gear utilizes (2) SSS-TOSI Reversible Coupling Converters (RCC’s) to provide reversing and slow speed maneuvering capability for each propulsion shaft.
The RCC is a fluid coupling/torque converter that has (26) insertable stator vanes positioned around the periphery of the rotor circuit. These stator vanes, when inserted, reverse fluid flow inside the RCC, and consequently reverse the direction of rotation of the RCC output (turbine) rotor. The RCC was tested extensively by the Naval Surface Warfare Center (formerly NAVSSES) in Philadelphia, Pa.
This paper provides an overview of the RCC design and operating principles; highlights of the prior testing accomplished; and an informative brief that details the successful integration, operation, and performance of the RCC aboard these new U.S. Naval vessels.
The Aerodynamics of Trailing-Edge-Cooled Transonic Turbine Blades: Part 1 — Experimental Approach
Authors: Deckers Mathias , Denton John D. 
Published: December 2014

The research presented in this part of the paper involved a detailed experimental study of the flow through transonic turbine blading with trailing edge coolant ejection. The tests were carried out on (nearly) flat plate models representing the region of uncovered turning downstream of the throat. The investigation focused on the aerodynamic aspects associated with trailing edge ejection in steady two-dimensional flow over a range of exit Mach numbers, coolant pressure ratios and temperature ratios.
The experiments showed that the simple existence of the coolant cavity leads to a substantial change of the flow field in the near wake. Consequently, the slotted unblown base was found to have considerably less loss than the solid one. The effect of coolant ejection is shown to cause a substantial increase in base pressure and reduction in overall loss. The surface static pressure distribution and boundary layers were affected by the coolant in two ways: directly from downstream, via the base pressure, and indirectly through a changed trailing edge shock system. However, the coolant stagnation temperature ratio was found to have no discernible effect on the base pressure and loss.
Flow Field Measurements on a Large Scale Turbine Cascade With Leading Edge Film Cooling by Two Rows of Holes
Authors: Ardey Sabine , Fottner Leonhard 
Published: December 2014

To increase the understanding of the aerodynamic processes dominating the flow field of turbine bladings with leading edge film cooling, isothermal investigations were carried out on a large scale high pressure turbine cascade. Near the stagnation point the blades are equipped with one row of film cooling holes on the suction side and one on the pressure side. Blowing ratio, turbulence intensity, Mach number, and Reynolds number are set to values typically found in modern gas turbines. Experimental data of the cascade flow were obtained by pneumatic probes and static pressure tappings. The flow field was visualized by Schlieren and oil flow techniques. For detailed investigations near the blowing holes the Laser Transit Velocimetry and the three dimensional Hot Wire Anemometry were used.
The flow field measurements in the near hole region of the suction side show the typical kidney shaped vortex pair. A local suction peak on the pressure side causes a large recirculation area behind the holes on the pressure side and induces separation bubbles in between the pressure side holes. This leads to the generation of two pairs of vortices: The kidney-vortex is located on top of a second vortex pair and a trough flow that fills up the deficit of the recirculation. Thus the film cooling air is detached from the pressure side surface. In addition to the mean flow vectors Reynolds stress components are a good means to judge the propagation of the jet. In spite of the complex flow pattern occurring on each single jet, the surveyed loss-increase due to the leading edge blowing can be predicted by the mixing layer model.