bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Guiding and Distributing Devices on the Exhaust Side of Stationary Gas Turbines
Authors: Fleischer Friedrich , Koerner Christian , Mann Juergen
Published: March 2015

Following repeated cases of damage caused to exhaust silencers located directly beyond gas turbine diffusers, this paper reports on investigations carried out to determine possible remedies.

In all instances, an uneven exhaust gas flow distribution was found to be present.

The company’s innovative approach to the problem involved constructing a scale model of a complete gas turbine exhaust system and using it for flow simulation purposes. It was established for the first time that, subject to certain conditions, the results of tests conducted on a model can be applied to the actual turbine exhaust system.

It is shown that when an unfavourable duct arrangement might produce an uneven exhaust flow, scale models are useful in the development of suitable flow-distributing devices.
Experimental Determination of Stator Endwall Heat Transfer
Authors: Boyle Robert J. , Russell Louis M.
Published: March 2015

Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.
Inviscid Cascade Flow Calculations Using a Multigrid Method
Authors: Arnone A. A. , Stecco S. S.
Published: March 2015

An accurate reliable and efficient computer code for inviscid cascade flow calculations has been developed and applied on sheared H-type grids. The integration in time is based on Jameson’s explicit Runge-Kutta scheme. Numerical efficiency is obtained through local time stepping, implicit residual smoothing and a full multigrid strategy. An additional wedge is added to blades with rounded trailing edges and care is taken to correctly capture the shock system when the outlet flow is supersonic. Comparison with experiments shows that the method can be applied to turbomachinery, yielding good blade-to-blade predictions.
Power Dissipation in Smooth and Honeycomb Labyrinth Seals
Authors: McGreehan W. F. , Ko S. H.
Published: March 2015

The surface frictional characteristics of a labyrinth seal can result in significant windage power dissipation for high speed seals. Recent advances in seal design have produced high speed, high pressure labyrinth seals which operate at very low leakage rates. The reduced leakage is beneficial to gas turbine efficiency, but seal discharge temperatures can approach material design limits with high windage power dissipation. Also, a high air temperature rise can influence seal leakage flow. Consequently, the general assumption of negligible rotational effect on leakage is not always valid. A method is presented for the prediction of seal power dissipation and leakage flow over a wide range of design parameters. Results are compared to available test data and several approaches examined for the reduction of seal windage.
Gas Turbine Operations of Synfuel Derived From Coal Gasification
Authors: Watts Donald H. , Gerstbrein Edward O. , Todd Douglas M.
Published: March 2015

A modified version of a commercially available General Electric MS7001E gas turbine has been successfully operated on synfuel derived from coal at the Cool Water Coal Gasification Program.

This paper addresses Cool Water’s experience with the MS7001E gas turbine in base load applications; starting and operating reliability; maintenance experience; modifications to the gas turbine including fuel delivery, combustion and control systems; and, future applications of advanced gas turbines in Integrated Coal Gasification Combined Cycle (IGCC) service.
The Prediction of Boundary Layers With Rotation and Variation of Stream Filament Thickness
Authors: Yaonan Hua , Baoguo Wang
Published: March 2015

The boundary layer equations with accounting for rotation and variation of stream filament thickness on the Sl stream surface of revolution in turbomachinery are derived in this paper. A method is presented for calculating laminar, turbulent and wake boundary layers by means of solving the integral momentum equation. The turbulent boundary layer with separation also can be calculated by use of present method.

The prediction of the boundary layer on the cascade blade of the DFVLR transonic axial compressor rotor was carried out in this paper. The effects of rotation and variation of stream filament thickness on the predicted behavior of the boundary layer are carefully investigated. It is shown that in certain cases their effects on the predicted results are significant.
Historical Review of the Development and Use of Marine Gas Turbines by the U.S. Navy
Authors: Carleton Richard S. , Weinert Eugene P.
Published: March 2015

This paper is a brief review of the U.S. Navy involvement in shipboard gas turbines starting with studies in the 1930’s and proceeding to the point where gas turbine propulsion has been chosen for all recent cruiser, destroyer and frigate class construction programs. It tells some of the false starts and lessons learned and accentuates the decision of the Navy to take advantage of the major developments in aircraft jet engines by using these same engines, marinized for use in a shipboard environment, to power many of our new combatants.
A Simplified Model for Unstable Temperature Field Calculation of Gas Turbine Rotor
Authors: Guangxin He
Published: March 2015

Fir-tree roots are usually adopted for rotor blades of gas turbine. Strictly speaking it should be treated as a three-dimensional problem for temperature field calculation of turbine rotor with fir-tree roots. In this paper, a simplified model is presented for calculating the unstable temperature field of a cooled turbine rotor by finite element method. In the simplified model, an outer radius Rb for calculating has been chosen which is smaller than the radius of the fir-tree root groove’s bottom. And an equivalent heat release coefficient α has been introduced. Thus the calculation can be treated as an axial symmetrical problem and carried out on a microcomputer. The simplified model has been used to calculate the unstable temperature field during starting a rotor. The comparison with the three-dimensional calculated result shows that the simplified model is satisfactory. For example, at 170th sec. after firing the temperature difference at the outer radius Rb is only 6% for the two methods.
Heat Transfer Measurements for Rotating Turbine Discs
Authors: Qureshi G. , Nguyen M. H. , Saad N. R. , Tadros R. N.
Published: March 2015

To optimise the turbine disc weight and coolant flow requirements, the aspect of improving thermal analysis was investigated. As a consequence, an experimental investigation was undertaken to measure the rates of convective heat transfer. The constant temperature steady state technique was used to determine the local and average heat transfer coefficients on the sides of rotating discs. The effects of coolant flow rates, CW (3000 ≤ CW ≤ 18600) with two types of cavity in-flow conditions and of the rotational speeds, Reθ (from 4×105 to 1.86×106) on the disc heat transfer were studied and correlations developed. For a rotating disc in confined cavities with superimposed coolant flows, Nusselt numbers were found to be higher than those for the free rotating disc without confinement.
Experimental Investigation of Supersonic Turbine Performance
Authors: Kurzrock John W.
Published: March 2015

This paper presents the performance obtained from testing single-stage, full-admission, axial supersonic turbine configurations. A matrix of four nozzle and two rotor blade configurations was evaluated. Turbine pressure ratios were varied from 33 to 140 for velocity ratios of 0.2 to 0.5. The test results indicate that constant-channel width and variable-channel width rotor blading give comparable performance. Optimal nozzle and blade configurations yielded turbine efficiencies of 77 percent.
High Temperature Coating for Improved Oxidation/Corrosion Protection
Authors: Wood J. H. , Foster A. D. , Schilke P. W.
Published: March 2015

As the firing temperatures of land-based gas turbines have increased in recent years, greater demands are being made on component materials. In particular, the increased surface metal temperatures of first stage buckets has shifted the nature of the protection required of bucket coatings from that of strictly high temperature hot corrosion resistance to that of both hot corrosion and oxidation protection. Characteristics of low temperature hot corrosion, high temperature hot corrosion and high temperature oxidation are presented. An overview of GE bucket coating materials is given and related to the types of corrosion and/or oxidation protection they provide. Evaluation of buckets removed from high firing, heavy duty gas turbines is presented. A new, more oxidation resistant coating, PLASMAGUARD™ GT-2 9 PLUS, developed and tested by GE to provide both oxidation and corrosion protection, is described. Bucket coating refurbishment recommendations are also made to maximize first stage bucket life. Current and future GE developmental work, both compositional and process, aimed at further improvements in bucket coating materials for oxidation protection of first stage buckets is also presented.
Marine Gas Turbine Infra-Red Signature Suppression: Aerothermal Design Considerations
Authors: Birk A. M. , Vandam D.
Published: March 2015

In recent years it has become evident that the Infrared (IR) Radiation given off by marine gas turbine exhaust systems is highly undesirable for naval vessels and commercial vessels traveling in areas of conflict. As a result, great interest has surfaced in the ways that IR signatures can be reduced. This paper presents an overview of some of the methods that can be used for engine exhaust IR signature suppression (IRSS). The methods considered here involve only ambient air addition for metal and plume cooling.

The present paper describes various IRSS systems and discusses the basic technical criteria for system selection. Basic operating principles are also described. Aerothermal design considerations are discussed and areas requiring special care during the design are highlighted. Because of the confidential nature of the subject, direct quantitative performance comparisons cannot be made.
The Coefficients of Discharge of Angled Chuted Holes
Authors: Winter J. , Stevens A. J.
Published: March 2015

The coefficients of discharge of a number of angled chuted holes, typical of those currently used in the primary and dilution zones of some small reverse flow combustors, have been determined on a two dimensional rig. Also evaluated were two types of “low cost” angled chuted holes. The paper describes the test rig, the geometry of the holes, the coefficient of discharge data, the sensitivity of the data to certain features and makes comparisons of the data with those for plain and plunged holes.
The Design and Performance of a Reverse Flow Combustion System for the TP 500 Gas Turbine Engine
Authors: Carr E. , Todd H.
Published: March 2015

The TP 500 is a 525 SHP turboprop engine being produced by Teledyne Continental Motors for general aviation use.

This paper describes the design and performance of the reverse flow fan spray combustion system being supplied for this engine. The main features of the design are described in some detail, together with the performance of the system as established in the combustion test facility at AIT Ltd and covering light-up to Take-Off conditions and sea level to 6km altitude.
Development of Steam Injection for Ruston TB5000 and Tornado Engines
Authors: Ecob D. J. , Marriott D. G.
Published: March 2015

Steam injection tests have been carried out on Ruston TB5000 and Tornado gas turbines. Steam was injected into the primary zone of the combustion chambers and the centre casings of both engines. Both engines were operated in twin shaft mode and the Tornado also in single shaft mode. The engines have been characterised for performance, emissions and combustion stability. Operational criteria have been defined and the thermodynamic changes in the cycle requiring modification in control parameters, during steam injection, have been identified.
Coal Generated Synthetic Gas Operating Experience With Two 100 MW-Class Combustion Turbines
Authors: Morrison E. M. , Pillsbury P. W.
Published: March 2015

Dow Chemical, U. S. A., is currently operating two Westinghouse W501D5 combustion turbines with synthetic gas from the commercial demonstration coal gasification unit at Plaquemine, Louisiana.

The first of these units was fueled with synthetic gas in April 1987. This conversion followed several years of experimentation and prototype work by Dow and Westinghouse. The second unit began operating with synthetic gas during September 1987.

Addition of synthetic gas capability to these combustion turbines, originally installed in December 1982 and May 1983, was relatively straightforward, and once installed, did not adversely affect their operation or efficiency on natural gas, or mixtures in various proportions with synthetic gas. For durability assessment, special instrumentation was maintained at the site in the months immediately following conversion. This facilitated making minor changes to improve combustor longevity.

The heat recovery units were modified for synthetic gas operation to improve corrosion resistance and to handle higher temperatures. Minor adjustments were made in the controls to accommodate changing gas flow. Emission monitoring was enhanced.
A Prototype Replacement of a 100,000 Hours Operation, 25,000 KW Gas Turbine at Idemitsu Kosan Co., Ltd.
Authors: Furukawazono R. , Ishino H. , Kamata T. , Kunihiro M. , Kubota M.
Published: March 2015

In September 1988, a Hitachi-GE model PG5341 gas turbine installed at the Tokuyama refinery of Idemitsu Kosan Co., Ltd. (Japan) successfully recorded 100,325 hours of base load operation over a period of 13 years with 99.4% reliability. The generated power totalled 1,341,770 MWh at the time of final shutdown.

The gas turbine, burning Bunker A oil, LPG, and heavy distillate oil, had been the main equipment in a cogeneration plant with a simple heat recovery steam generator using waste heat from the exhaust gas, plus a refired boiler.

It was expected that several costly hot gas path components of this turbine would have to be replaced in the near future, and it was not as fuel efficient as more modern designs, so it was decided to replace the PG5341 with a Hitachi H-25 gas turbine.

This new model H-25 is designed to have a rated output of 26,200kW and an efficiency of 32.3% (LHV) at the generator terminals under ISO conditions. By the use of a pressure ratio of 14.7 (up from 10.1) and a combustor outlet gas temperature of 1,260°C (up from 980°C), it is expected that efficiency of gas turbine will be improved relatively by 18.7% on a design basis, compared with the PG5341.

A factory full-load test of the prototype H-25 gas turbine was completed in August 1988 with excellent results. This machine has been in place and in operation at the Tokuyama plant since the end of November 1988. This is the first commercial application of the Hitachi H-25 advanced gas turbine.
Burner Rig Evaluation of Ceramic Coatings With Vanadium-Contaminated Fuels
Authors: Nagaraj B. A. , Wortman D. J.
Published: March 2015

The performance of yttria stabilized zirconia (YSZ), ceria stabilized zirconia (CSZ), and magnesia stabilized zirconia (MSZ) coatings was evaluated using an atmospheric burner rig; the test environment contained compounds of vanadium, sodium and sulfur. The coatings were deposited by plasma spraying and electron beam physical vapor deposition (EB-PVD); sputtered sealant layers of hafnia, alumina and platinum were deposited on the yttria stabilized zirconia coating (YSZ). The tests were performed for up to 500 hours at 1650°F and 1300°F. The tests were designed to simulate the deposit chemistry and sulfur trioxide partial pressures expected in a marine gas turbine engine operating on contaminated fuel.

YSZ, CSZ, and MSZ coatings all underwent reaction in the burner rig environment; the reaction products and their effects on spallation were varied. MSZ was by far the most reactive, readily forming MgSO4 in both 1650°F and 1300°F tests. The observed reaction products provided a measure of “protection” for the bond coat by preventing molten salt infiltration in the duration of the test. The mechanism of ceramic spallation is discussed. Sputtered overlayers of platinum, hafnia and alumina did not prevent salt infiltration and reaction with the underlying ceramic, although no reaction product between the overlayer and the salt was observed.
Spray Characterization and Turbulence Properties in an Isothermal Spray With Swirl
Authors: De La Rosa A. Breña , Bachalo W. D. , Rudoff R. C.
Published: March 2015

The present work reports an experimental study of the effect of swirl on the dynamic behavior of drops and on the velocity and turbulence fields of an isothermal spray using a two-component Phase Doppler Particle Analyzer (PDPA). It represents the first phase of an effort to investigate the effect of swirl on the structure of liquid spray flames, the stability of the flame, and its effect on the emission of pollutants. A vane type swirler was placed on the liquid supply tube of a pressure atomizer and tested in the wind tunnel under specified conditions. Mean velocity and turbulence properties were obtained for the gas phase. In addition, drop velocity and drop size distributions, particle number densities, and volume flux were measured at different locations within the swirling flow. Large differences in the spatial distribution of the drops over its size, velocity, and number density are observed when the spray in a co-flowing air with the same axial velocity is compared with the atomizer spraying into the swirling flow field. Large drops seem to be recirculated into the core of the swirling flow, while rather small drops surround this central region. The radial distribution of particle number density and liquid volume flux are also different when the atomizer spraying into the co-flowing air and into the swirling field are compared. Particle number densities for the latter exhibit higher peak values close to the nozzle but show almost the same peak values as the quiescent spray but at different radial location further downstream. The velocity of specific drop sizes was also obtained. Drops as large as 5 μm are seen to follow closely the mean velocity of the gas. The turbulence properties of the swirling flow show significant influence on the dynamic behavior of the drops. Radial distribution of turbulence kinetic energy, normal Reynolds stresses, and Reynolds shear stresses exhibit double peak values which delineate the boundaries of the central recirculation region and the external free stream. Within these boundaries the radial distribution of both particle number density and volume flux are seen to attain their maximum values.
An Improved Incidence Losses Prediction Method for Turbine Airfoils
Authors: Moustapha S. H. , Kacker S. C. , Tremblay B.
Published: March 2015

The off-design performance of axial turbines is usually predicted by calculating the incidence losses using empirical correlations. Periodic review and improvement to these prediction methods, to reflect recent turbine designs and test results, are essential for the accurate assessment of losses in turbine airfoils. The purpose of the present work is to evaluate existing turbine incidence loss correlations, and present an improved prediction method for profile and secondary losses at off-design conditions which correlates better with the available experimental results. The incidence losses are shown to be a function of leading edge diameter, pitch, aspect ratio and channel convergence.
Unsteady Transition in an Axial Flow Turbine: Part 1 — Measurements on the Turbine Rotor
Authors: Addison J. S. , Hodson H. P.
Published: March 2015

Previously published measurements in a low speed, single stage, axial flow turbine have been reanalysed in the light of more recent understanding. The measurements include time-resolved hot wire traverses and surface hot film gauge measurements at the midspan of the rotor suction surface with three different rotor-stator spacings. Part 1 investigates the suction surface boundary layer transition process using surface-distance time plots, and boundary layer cross sections to demonstrate the unsteady and two-dimensional nature of the process. Part 2 of the paper will describe the results of supporting experiments carried out in a linear cascade together with a simple transition model which explains the features seen in the turbine.
On the Mechanism of Dangerous Blade Vibration due to Blade Flow Interactions on Centrifugal Compressors
Authors: Haupt U. , Jin D. F. , Rautenberg M.
Published: March 2015

Severe blade flow interactions at part load operation conditions were investigated on a centrifugal compressor with a vaned diffuser leading to material stresses beyond the allowable values. By means of a number of measurement and analysis techniques it could be found, that a stationary periodic pressure field is produced on the circumference by the vibrating blade itself, which is induced at resonance conditions by the peripheral pressure non-uniformity due to the outlet tube. This peripheral pressure field of an integer wave number intensifies the blade resonance excitation from downstream leading to an additivity effect between wave amplitude and blade displacement. The significant role in this mechanism plays the reverse flow near the corner shroud/suction side in the impeller, occurring at part load operation, which is controlled by the interaction of the tip angle of the vibrating blade and the flow angle at that location. It could be demonstrated, that this dangerous blade vibration — in addition — is the source of a shift of the surge line towards higher mass flow, reducing the compressor operating range considerably in this operating zone.
Design and Test of the FT8 Gas Turbine Low Pressure Compressor
Authors: Monhardt R. J. , Richardson J. H. , Boettcher J. M.
Published: March 2015

This paper presents a discussion of the design and test phases of the Low Pressure Compressor (LPC) used in the FT8 Gas Turbine. Design objectives, including efficiency, durability and stall margin goals are covered along with actual test results indicating successful accomplishment of these objectives. Unique features of the test program and an overview of the FT8 Gas Generator in comparison to the JT8D Aircraft Engine are also presented.
Intercooled and Recuperated Dresser-Rand DC990 Gas Turbine Engine
Authors: Staudt James E. , Birkholz Dietrich , Jansen Willem , Tuzson John J.
Published: March 2015

A preliminary design for a Dresser-Rand DC990 industrial gas turbine engine modified for intercooling and recuperation (ICR) is presented. The DC990 was selected because its configuration is amenable to intercooling and because it is in the power range of interest. Based upon preliminary estimates, engine power output will increase from 6000 bhp to 8400 bhp at design point. Design point specific fuel consumption will be reduced 26% to a heat rate of 6300 BTU/bhp-hr. Moreover, the DC990 ICR engine maintains a high thermal efficiency during part-load operation. These performance improvements are achievable using proven, low-risk technology. The resulting combination of low fuel consumption and low maintenance costs makes the DC990 ICR gas turbine engine an attractive engine package for several applications.
Unsteady Lifting Surface Theory for a Rotating Cascade of Swept Blades
Authors: Kodama Hidekazu , Namba Masanobu
Published: March 2015

A lifting surface theory is developed to predict the unsteady three-dimensional aerodynamic characteristics for a rotating subsonic annular cascade of swept blades. A discrete element method is used to solve the integral equation for the unsteady blade loading. Numerical examples are presented to demonstrate effects of the sweep on the blade flutter and on the acoustic field generated by interaction of rotating blades with a convected sinusoidal gust. It is found that increasing the sweep results in decrease of the aerodynamic work on vibrating blades and also remarkable reduction of the modal acoustic power of lower radial orders for both forward and backward sweeps.
Automated Welding of Turbine Blades
Authors: Liburdi J. , Lowden P. , Pilcher C.
Published: March 2015

The welding of superalloys has been regarded, generally, as an art requiring the highest degree of welder skill and discipline. These highly alloyed materials are prone to micro-cracking and, in some cases, even the best welders cannot achieve satisfactory results.

Now, however, advances in automation technology have made it possible to program precisely the complex airfoil shapes and the welding parameters. Consequently, turbine blades can be welded in a repeatable manner, with a minimum of heat input resulting in better metallurgical quality both in the base metal and the weld deposit. The application of this technology to the automated welding of high-pressure compressor turbine blade tips, and the refurbishment of low-pressure turbine blade shrouds are presented in this paper.
Ceramic Composites for Gas Turbine Engines via a New Process
Authors: Schiroky G. H. , Urquhart A. W. , Sorenson B. W.
Published: March 2015

A new process for ceramic composites involves the growth of ceramic matrices through shaped preforms using directed oxidation reactions of molten metals. The preforms may consist of reinforcing fibers, whiskers, platelets, or particles, as needed to produce the desired properties in the finished component. This new technology is being developed by Lanxide Corporation and is being applied to gas turbine engine components by Du Pont Lanxide Composites Inc., a joint venture. The paper includes a description of the technology and a discussion of the status of its application to materials for gas turbine engine components.
The Automation of the Manufacture of Small Gas Turbine Compressor Blades
Authors: Pratt A. J. S. , Glew D. A. , McIntyre C. T.
Published: March 2015

The paper describes an automated manufacturing system installed to produce accurate high performance compressor blades. The automation handles the material from input through the machining operations, which include broaching for root features, and ECM for aerofoils, to the finished inspected component. Finished parts can be produced from either rolled rectangular bar or from oversize forging preforms, yielding blade throughputs up to one thousand per week from each unit.
Ultra Low NOx Emissions for Gas and Liquid Fuels Using Radial Swirlers
Authors: Alkabie H. S. , Andrews G. E.
Published: March 2015

Curved blade radial swirlers using all the primary air were investigated with applications to lean burning gas turbine combustor primary zones with low NOx emissions. Two modes of fuel injection were compared, central and radial swirler pássage injection for gaseous and liquid fuels. Both fuel systems produced low NOx emissions but the upstream mixing in the swirler passages resulted in ultra low NOx emissions. A 140mm diameter atmospheric pressure combustor was used with 43% of the combustor air flow into the primary zone through the radial swirler. Radial gas composition measurements at various axial distances were made and these showed that the flame stability and NOx emissions were controlled by differences in local mixing at the base of the swirling shear layer downstream of the swirler outlet. For radial passage fuel injection it was found that a very high combustion efficiency was obtained for both propane and liquid fuels at 400K and 600K inlet temperatures. The flame stability, although worse than for central fuel injection was considerably better than for a premixed system. The NOx emissions at one bar pressure and 600K inlet temperature, compatible with a high combustion efficiency, for propane and kerosene were 3 and 6 ppm at 15% oxygen. For Gas Oil the NOx emissions were higher, but were still very low at 12ppm. Assuming a square root dependence of NOx on pressure these results indicate that NOx emissions of 48ppm for Gas Oil and less than 12ppm for gaseous fuels could be achieved at 16 bar pressure, which is typical of recent industrial gas turbines. High air flow radial swirlers with passage fuel injection have the potential for a dry solution to the NOx emissions regulations.
The Calculation of the Three-Dimensional Flow Through a Transonic Fan Including the Effects of Blade Surface Boundary Layers, Part-Span Shroud, Engine Splitter and Adjacent Blade Rows
Authors: Cedar R. D. , Holmes D. G.
Published: March 2015

In the past, predictions of the three-dimensional flow through turbomachinery blades have often assumed that:-

a) The blade passage forms a single channel.

b) The effects of adjacent blade rows and engine structures are negligible.

c) The flow is inviscid.

Unfortunately, for a transonic fan in a high bypass ratio aero-engine, these assumptions are poor because:-

a) The blade passage is split into a number of channels by the part-span shroud and the engine splitter.

b) The fan aerodynamics may be influenced by the presence of the engine splitter and downstream blade rows.

c) The blockage due to the blade surface boundary layers can have a significant effect on the shock structure.

This paper describes the extensions that have been made to the three-dimensional Euler solver developed by Holmes and Tong (1985) in order to remove the assumptions listed above. The problem of modeling the part-span shroud and the engine splitter has been generalized to that of solving a flow containing any number of internal solid bodies. This has been achieved in a novel manner that allows the finite volume scheme to be fully vectorized and the multigrid acceleration technique to be implemented efficiently. The effect of adjacent blade rows has been modeled using passage averaged mass, momentum and energy source terms to represent the neighboring blades in a similar manner to that described by Adamczyk, Mulac and Celestina (1986). The blade surface boundary layers have been modeled using a series of two-dimensional boundary layer calculations coupled to the Euler solver using a transpiration model to account for the boundary layer displacement thickness. To demonstrate the capabilities of this program, results from the analysis of a General Electric advanced fan blade design, with a part-span shroud, engine splitter and down-stream stator and rotor blade are presented. This is followed by an investigation and discussion of the individual effect of not modeling the viscous blockage, the part-span shroud engine, splitter and down-stream blade rows. It is concluded that if an accurate prediction of the fan aerodynamics is to be obtained all these features must be modeled.
A Method for the Prediction of Supersonic Compressor Blade Performance
Authors: Freeman C. , Cumpsty N. A.
Published: March 2015

A simple model is used to calculate the flow in compressor blades with supersonic relative inlet flow. The one-dimensional model utilises the conservation of stagnation enthalpy, mass flow and momentum in the inlet region. The momentum equation is applied in the direction parallel to the blade surface at inlet and one of the fundamental simplifications adopted is that the projected area of the blades gives such a small force in this direction that a very simple approximation for it suffices.

The model is able to predict the loss creation in the inlet region. The level of predicted loss agree well with measured values when the Mach numbers are sufficiently high for the inlet loss to dominate. Furthermore the correct trends of loss with incidence and blade speed are predicted. The pressure rise and flow can also be predicted when the correct deviation and meridional streamtube convergence are given. The method predicts trends usually seen in measurments: the narrowing of the useful operating range between choke and flow instability (surge) as blade speed is increased and a steepening of the surge line at the higher speeds.
Directional Solidification of Land-Based Gas Turbine Buckets
Authors: Peterson Lance G.
Published: March 2015

Improvements in land-based gas turbine performance require materials capable of operating at increasingly higher temperatures. Innovative approaches to alloy and process improvement, such as directional solidification, can meet the more demanding conditions of new gas turbine designs. This paper outlines GE TBO’s multi-faceted research program for the development of directionally solidified GTD-111 first stage turbine buckets. Included are discussions of the theoretical background, casting program, mechanical tests and machining studies.

The GTD-111 directional solidification program successfully met the technological challenges encountered in scaling up directional solidification experience from relatively small aircraft parts. Directionally solidified buckets are in production for several first stage product lines. Improvements in mold technology coupled with experience gained in the on-going research program indicate that more complex parts as well as single crystal parts are now feasible.
The Coatability of ODS Superalloys
Authors: Benn R. C. , Smith G. D. , Boone D. H.
Published: March 2015

There has been a need for suitable coatings to provide protection for a sufficient length of time to match the outstanding high temperature strength capabilities of Mechanically Alloyed (MA) ODS superalloys. The quest for such coatings has instigated many research studies. The findings reported here evolved from studies on substrate composition effects and coating application types and structures that are necessary in order to develop viable substrate-coating systems. The systems were evaluated using cyclic and isothermal oxidation tests and Burner Rig hot corrosion (sulfidation) tests. The results indicate, inter alia, beneficial substrate compositional effects from Al in high Al/γ′ phase superalloys. Compatible overlay coatings of, for example, NiCoCrAlY(Ta) for INCONEL* alloy MA 6000 and advanced industrial ODS superalloys, such as INCONEL alloy MA 760, were identified that are commercially available. These conclusions are supported by initial results from a much broader coatability program currently in progress. This program also includes several combinations of duplex coatings, utilizing a compatible inter-layer coating, that have enhanced both coatability and corrosion resistance performance of these Ni-based ODS superalloys.
Modified Fuel Control for a Large Heavy-Duty Combustion Turbine-Generator
Authors: Quentin G. , Brawley G. , Loft A. , Perez-Daple W.
Published: March 2015

Thermal transients during start-up and shutdown of a heavy-duty gas turbine stress the hot gas path components and reduce their effective life due to low-cycle fatigue. Experience has shown that stress-related cracking and wear is more extensive on gas turbines in cyclic service that start and stop more frequently, than machines in baseload service that operate more continuously.

The start-up schedules of most engines in peaking duty are generally designed to minimize the time to reach full load. Rapid loading is not a critical element for many gas turbine users, who would prefer alternate start-up schedules that could extend component life, by as much as a factor of three.

It is the fuel controls that dictate thermal energy input to a combustion turbine during start-up and shutdown. Therefore, experiments performed on the rates of acceleration and deceleration led to modified fuel controls for a natural gas-fired combustion turbine (General Electric Model MS7001B), Unit 41 at the T. H. Wharton Plant of Houston Lighting & Power Co. The results may be generalized and applied to other gas turbines and control systems, using different fuels.

Specific findings relate to quicker ignition, more gradual initial warm-up, a lower acceleration for a soft start, and lower deceleration during fired shutdown. Additionally, new minimum fuel settings enhanced running reliability during load-shedding operation with water injection for NOx control. The results are described and illustrated in detail to demonstrate the new start-up and shutdown sequence. Subsequently, one HL&P unit was permanently modified for check-out, and across-the-board updating of other units is planned.
A Methodology Proposal to Design and Analyse Counterrotating High Speed Propellers
Authors: Nicoud D. , Brochet J. , Goutines M.
Published: March 2015

Contrarotating high speed propellers are able to significantly reduce fuel consumption of high subsonic aircrafts. The achievement of this goal requires the optimization of the transonic flowfield on the blades in order to obtain high efficiency. For several years, 2D and 3D aerodynamic computational methods have been used to design high performance turbofans. A similar methodology can be developed for high speed propeller design, and this paper presents a typical application of such methods.

We first present an application of the through-flow method. An outer fictitious casing is chosen in order to simulate undisturbed flow far from the propellers, and the mesh is adapted to the high swept blades. Radial distribution of loading is selected using aerodynamic criteria.

Then, a quasi geometrical method supplies the bidimensional profiles accounting for structural specifications such as chord length, maximum thickness and root attachment. Suction side incidence and downstream deviation are also specified. After the profile stacking operations, which use conformal application on the axisymetric stream surfaces, the tridimensional transonic flowfield is drawn by a 3D Euler solver on an appropriate domain. This code uses a multi-domains technique and includes the energy equation for non-constant rothalpy cases. Particular interest is focused on the Mach number distributions and on the shock strength. The final loss prediction is made by means of a shock loss model and a bidimensional boundary layer calculation based on the Euler static pressure distributions.

The profile shapes are modified and the above process is repeated until the required deflection, a convenient throat margin, and sufficiently thin and well attached boundary layers are obtained. Finally, the global performances are issued from 3D Euler and boundary layer computations, completed by the calculation of secondary flow effects.
Optimum Shape Design of Rotating Disks and Experimental Research
Authors: Yu Xiaoming , Ma Mei , Chen Guang
Published: March 2015

The concept of control node and control equation is introduced for geometrical definition in this paper. The idea of the combined function representation of shape is presented. An important tool of interactive adaptive mesh refinement is developed to achieve an adequate finite element model in the optimization process and to reduce CPU time. A semi-analytical method of sensitivity derivatives calculation is proposed. A shape optimization system of rotating disks (SOPD.BUAA) is developed and applied to design a gas turbine disk. This system is demonstrated by experiments on initial disk and optimal disk.
Boundary Layer Calculation Including the Prediction of Transition and Curvature Effects
Authors: Guyon B. , Arts T.
Published: March 2015

The calculation of surface temperature on gas turbine blades in severe operating conditions requires a detailed knowledge of boundary layers behaviour. The prediction of laminar to turbulent transition as to existence and location, as well as the evaluation of heat transfer rates are major concerns.

The program developed by SNECMA for this purpose is presented, in which models are introduced to take into account the main effects occuring on blades without film-cooling. The algorithm and discretisation scheme for boundary layer equations is Patankar and Spalding’s, with profiles initialization by Pohlhausen’s method. The turbulence and transition model, after Mc Donald and Fish, was improved in search for more stability and to have a better detection of the beginning of the transition. Adams and Johnston’s model for curvature, including propagation effects, was adapted to a transitional boundary layer.

The validation tests of this program are described, which are based on numerous experimental data taken from a bibliography of tests over flat plates and blades. Other tests use heat transfer rate measurements conducted by SNECMA, together with VKI, on vanes and blades in non-rotating grids. The calculation results are further compared to the STAN5 program results; they show a superiority in predicting the transfer rates on a convex surface and for transitional boundary layers.
Accuracy and Reproducibility of Temperature Measurement by Thermocouples
Authors: Wang T. P.
Published: March 2015

The accuracy of base metal thermocouples in initial condition and after service is reviewed in conjunction with the accuracy and reproducibility of measurement and factors affecting calibration. Lot calibration data on insulated thermocouple wire and metal sheathed thermocouples are examined on a statistical basis. Some stability test data on K, J, T and E thermocouples in air atmosphere are presented. Calibration data by standard methods are compared with those obtained by data acquisition and freeze point measurements. Round-robin calibration of J and K thermocouples is included for the determination of the uncertainty of calibration by J and K thermocouples. By integrating the information on initial calibration and stability of the thermocouple with the accuracy of measurement, one is in a position to select the best system for close temperature control throughout a process.
Accelerated Computation of Viscous, Steady Incompressible Flows
Authors: Lee Seungsoo , Dulikravich George S.
Published: March 2015

Based on an artificial compressibility method, the explicit Runge-Kutta time stepping finite difference algorithm was applied to steady, incompressible, Navier-Stokes equations. A two-dimensional analysis computer code in a generalized curvilinear coordinate system was developed and its accuracy has been compared to known numerical solutions. The algorithm has been accelerated using our new Distributed Minimal Residual (DMR) method, which allows each equation in the system to advance in time with its own optimal speed. The effectiveness of the DMR method was examined for a number of test cases. The accelerated algorithm offers substantial savings of the computing time.
Secondary Loss Generation in a Linear Cascade of High-Turning Turbine Blades
Authors: Harrison S.
Published: March 2015

Flow through a linear cascade of high-turning, low aspect ratio turbine blades has been measured in great detail at five planes within the cascade and two downstream in order to trace the generation of stagnation pressure loss in the passage. Five-hole probes were used in the main flow but as it is important to resolve the boundary layers accurately three-hole and single flattened probes were used near the end wall and blade surfaces respectively. End wall shear stresses have been measured using a hot-film probe and an oil-drop viscosity balance technique. Numerical predictions and simple aerodynamic models are used in conjunction with the experimental data to estimate the relative importance of different loss mechanisms, including boundary layer shear stresses and mixing processes.
Fiber Optic Probe for Flame Monitoring in Gas Turbine Combustors
Authors: Morey W. W. , Quentin G. H. , Angello L. A.
Published: March 2015

A new probe, utilizing fiber optics, has been developed that allows one to view the flame inside an industrial gas turbine combustor. The probe was tested on a GE 7001 gas turbine at Houston Lighting & Power’s T. H. Wharton plant. Views of the flame were recorded at the nozzle and from in front of the nozzle to the combustor exit. A small portion of the flame in the adjoining combustor could also be viewed through the connecting cross fire port.

During field testing with the probe, we observed such events as delayed ignitions, start ups, and load changes. Different flame patterns could be associated with different turbine operating conditions in start up and loading sequences. An interesting flame instability was observed during engine loading where the flame attaches and detaches from the fuel nozzle. At full power the flame is fully detached from the nozzle and extends from the cross fire port to the combustor exit. Plots of flame centroid position can be correlated with the turbine load. Operators, familiar with the flame image, could diagnose certain engine malfunctions such as fuel nozzle fouling, loss of water injection, and liner damage. A viewing system is currently under development that will monitor all the combustor flames simultaneously on one video screen. This system will significantly enhance operator diagnostics by allowing comparisons between combustors and detecting imbalances or differences between combustor flames.
Flow Field Investigation in a Low Solidity Inducer by Laser Doppler Velocimeter
Authors: Boccazzi A. , Perdichizzi A. , Tabacco U.
Published: March 2015

The results of an experimental investigation of the flow-field within a low solidity inducer at design and off design flow rate are presented and discussed; particular attention is devoted to the analysis of the flow-field, at the tip in front of the leading edge, for the flow rate close to the back-flow onset.

The flow-field was measured by means of a laser doppler velocimeter at four different axial positions: upstream, within and downstream of the inducer. Axial, tangential and relative flow angle distributions, in the measuring planes, are presented for three different flow coefficients.

At the lower flow rate, the plots show the presence of reverse flow in the region close to the hub downstream of the trailing edge. For the same flow rate, quite low axial velocities are detected at the tip. This is in agreement with pressure probe traverses carried out in a slightly downstream section; these measurements also show radial inward velocities of the same order of magnitude as the axial velocities.

Circumferentially averaged losses were evaluated from specific work and total head rise given by pressure probes.
Tip Leakage Losses in a Linear Turbine Cascade
Authors: Dishart Peter T. , Mdore John
Published: March 2015

An investigation of lip leakage flow and its effects on loss production was performed on a large scale linear turbine cascade having a tip gap measuring 2.1% of the blade height. The flow exiting the tip gap was measured to determine the tosses incurred within the tip gap and the secondary kinetic energy due to tip leakage. Additional measurements, 40% of an axial chord downstream of the blade trailing edges, showed the development of the leakage flow and the overall cascade losses. At the downstream location, the additional loss due to lip leakage was found to be the sum of the measured loss at the tip gap exit plane and the amount of tip gap secondary kinetic energy which had been dissipated by that downstream location.