bluuebunny/crossref_metadata_2025 huggingface dataset:
The Development of a Machinery Condition Monitoring System for Gas Transmission
Authors: Van Hardeveld Thomas
Published: March 2015

Over the past few years, there has been accelerated development in predictive maintenance techniques such as condition monitoring. This paper describes the development of a condition monitoring system which monitors gas compression equipment for a major gas transmission company. A stand-alone system, featuring a data collector and PC-based software, was implemented first to allow for medium to longer-term trending. Subsequently, an on-line system has been developed to facilitate automatic acquisition of data and enhanced monitoring capabilities. Various diagnostic techniques have been included in both the stand-alone and on-line systems to aid in data interpretation and analysis.
Stopping and Reversing High Power Ships
Authors: Clements H. A.
Published: March 2015

In 1979 and 1982, papers were presented at ASME Gas Turbine Conferences regarding the new design of Reversible Converter-Coupling (RCC) used in combination with a direct drive clutch, within reduction gearing, to provide a high power reversing gearbox. This paper now reviews reversing gear history and the extensive testing of the RCC. The paper also outlines ship stopping characteristics and gives information regarding the use of the RCC with a direct drive clutch in the Italian Navy ship ‘Giuseppe Garibaldi’.
Performance of a Highly-Loaded HP Compressor
Authors: Calvert W. J. , Ginder R. B. , McKenzie I. R. I. , Way D. J.
Published: March 2015

A 4-stage axial research compressor, which is representative of the rearmost stages of a highly-loaded military or civil compression system, has been designed and tested at RAE Pyestock. The compressor is of large scale, with extended inter-row gaps, to facilitate the acquisition of detailed aerodynamic data. The unit performed well on test, exceeding its design pressure ratio of 4.0, and achieving a peak polytropic efficiency at design speed of 89%. Flow profiles obtained from area traversing at stator exits are presented and discussed. The measured performance is compared with an S1-S2 calculation incorporating an inviscid-viscous blade-to-blade method.
Advanced Core Technology: Key to Subsonic Propulsion Benefits
Authors: Glassman Arthur J. , Snyder Christopher A. , Knip Gerald
Published: March 2015

A study was conducted to identify the potential performance benefits and key technology drivers associated with advanced cores for subsonic high-bypass turbofan engines. Investigated first were the individual sensitivities of varying compressor efficiency, pressure ratio and bleed (for turbine cooling); combustor pressure recovery; and turbine efficiency and inlet temperature on thermal efficiency and core specific power output. Then, engine cycle and mission performance benefits were determined for systems incorporating all potentially achievable technology advancements.

The individual thermodynamic sensitivities are shown over a range of turbine temperatures (at cruise) from 2900 to 3500 °R and for both constant (current technology) and optimum (maximum thermal efficiency) overall pressure ratios. It is seen that no single parameter by itself will provide a large increase in core thermal efficiency, which is the thermodynamic parameter of most concern for transport propulsion. However, when all potentially achievable advancements are considered, there occurs a synergism that produces significant cycle and mission performance benefits. The nature of these benefits are presented and the technology challenges associated with achieving them are discussed.
Mechanical and Process Design of the Flevo Power Station Conversion Project
Authors: Feenstra J. , Kamminga P.
Published: March 2015

EPON operates a number of power stations in the north of the Netherlands. At some of these the forced-draught-fans have been replaced by gas turbines. Unit 3 of Flevo Power Station was the latest repowering project in the Netherlands.

This paper gives a description of the most important points of the mechanical, and process design of the combined cycle unit and the influence of the gas turbine on the starting procedure.
Application of Numerical Models for Predictions of Turbine Engine Combustor Performance
Authors: Burrus D. L.
Published: March 2015

Rapid advances in available computer technology in the past ten years coupled with the ever increasing costs associated with gas turbine combustor development testing led to considerable interest in the development of sophisticated numerical methods for the design and analysis of turbine engine combustors. The development and refinement of these methods has been taking place at GE Aircraft Engines since 1980 as part of an ongoing research and development project. Efforts associated with this project have achieved considerable progress to date, including the development of 2D/axisymmetric and full 3D versions of an improved elliptic numerical model (CONCERT), suitable for application to combustor related flow problems. The application of CONCERT to typical combustor performance problems has demonstrated its capabilities to provide useful and accurate design information resulting in less dependence on component testing. This has resulted in engineering productivity improvement and reduced costs associated with combustor performance development.
Development of a Dry Low NOx Combustor
Authors: Davis L. B. , Washam R. M.
Published: March 2015

Controls for emissions of oxides of nitrogen were first required for gas turbines by the Los Angeles County Air Pollution Control District (LAAPCD) and the San Diego Air Pollution Control District (SDAPCD) in the early 1970’s. To achieve the necessary control, water was injected into the combustor flame zone to reduce flame temperature. The consequent reduction in NOx amounted to about forty percent when half as much water as fuel was injected into the reaction zone. The emissions level achieved was approximately 75 ppmvd (parts per million by volume dry) on oil fuel as required by SDAPCD Rule 68, and with the airflow of these MS5000 machines at about 950,000 lbm/hr, this corresponded to 140 lbm/hr of NO2 when expressed at 15% O2 as required by LAAPCD Rule 67. Hilt and Waslo, (Ref. 1) and Hilt, et al (Ref. 2, 3) provide summary discussions of this work.
A Basic Analysis of Cogeneration Economics
Authors: Collet P. J.
Published: March 2015

The economics of small scale gas turbine based cogeneration systems are analyzed on the basis of avoided costs for an electric utility exploiting such systems. This concerns a theoretical study in which the cogeneration system as a means for electricity generation is assumed to supplant the building of new central electricity generating plant.

The results show that with increasing oil and gas price levels, the economics of cogeneration will become more favourable when the supplanted capacity is for peak load rather than for base load electricity generation. This implies a preference for applications with cogeneration operation taking place mainly during on-peak hours of the electricity demand.
Applying Nontraditional Machining Techniques for Improved Turbine Engine Designs
Authors: Rhoades Lawrence J.
Published: March 2015

Developments in nontraditional machining techniques can result in the manufacture of gas turbine engines that are lighter, more powerful and more fuel efficient. Processes such as abrasive flow machining, laser drilling, ECM, EDM, orbital abrading and ultrasonic machining are capable of machining advanced “engineered” materials with complex shapes requiring close tolerances and fine surface finishes. Encouraging the development and use of nontraditional machining techniques in turbine engine applications can accelerate the introduction of more advanced engine designs.
Effects of Adverse Pressure Gradients on the Nature and Length of Boundary Layer Transition
Authors: Walker G. J. , Gostelow J. P.
Published: March 2015

Existing transition models are surveyed and deficiencies in previous predictions, which seriously overestimate transition length under an adverse pressure gradient, are discussed. A new model for transition in an adverse pressure gradient situation is proposed and experimental results are provided which confirm its validity. A correlation for transition length is advanced which incorporates both Reynolds number and pressure gradient effects.

Under low free-stream turbulence conditions the basic mechanism of transition is laminar instability. There are, however, physical differences between zero and adverse pressure gradients. In the former case transition occurs randomly, due to the breakdown of laminar instability waves in sets. For an adverse pressure gradient the Tollmien-Schlichting waves appear more regularly with a well-defined spectral peak. As the adverse pressure gradient is increased from zero to the separation value the flow evolves continuously from random to periodic behavior and the dimensionless transition length progressively decreases.
Improvements to the Performance of a Prototype Pulse, Pressure Gain, Gas-Turbine Combustor
Authors: Kentfield J. A. C. , Fernandes L. C. V.
Published: March 2015

A description is given of a simple, prototype, pulse, pressure-gain, combustor for a gas turbine. The work reported was targeted at alleviating problems previously observed with the prototype combustor. These were related to irreversibilities, causing a performance deficiency, in the secondary flow passage. The work consisted of investigating experimentally the effect of tuning the secondary-flow path-length, adding a flow restrictor at the combining-cone entry station and redesigning the combining-cone itself. The overall result was to eradicate the previously noted performance deficiency thereby increasing the maximum pressure-gain obtained in the gas turbine from 1.6% to 4.0% of the compressor absolute delivery pressure.
An Euler Solution for Unsteady Flows Around Oscillating Blades
Authors: He L.
Published: March 2015

A time-marching Euler calculation for 2-D and quasi 3-D unsteady flows in oscillating blade rows is presented, based on a finite volume scheme with cell-vertex discretization in space and 2-step Runge-Kutta integration in time.

Extra fluxes due to the deformation of the moving finite volumes are directly included in the conservation equations in the physical coordinate system. A zonal moving grid technique is used, in which only sub-regions near oscillating blades are moved to fit both the moving (blade) boundaries and fixed regions.

For phase-shifted periodic conditions, the conventional ‘Direct Store’ method is used as a basis for comparison. Two alternative methods to save computer storage are proposed and preliminary demonstrations of their usefulness are given in the present calculations.

Calculated results for unsteady flows in an oscillating flat plate cascade are in good agreement with those from two well-established linear methods, LINSUB and FINEL. The unsteady pressure distribution and aerodynamic damping calculated by the present method for a turbine blade test case (Aeroelasticity Workshop Standard Configuration No.4 cascade) agree well with the corresponding experimental data. Computations for an oscillating biconvex cascade in transonic flow conditions are performed, which show some strong nonlinear behavior of shock wave movement.
Real Time Performance Analysis and Condition Monitoring of a Gas Turbine Based 300 MW Base Load Cogeneration Plant
Authors: Haub Gary L. , Hauhe William E. , Myers Charles O.
Published: March 2015

This paper describes the performance monitoring and analysis system that is in use at a base loaded 300 MW cogeneration facility, which supplies 1.903 million lb/hr (0.863 million kg/hr) of wet steam for thermally enhanced oil recovery operations. The current state of the development of the performance monitoring system (in use since late 1985), the hardware used throughout the system, the theory of performance analysis, software development, and the reporting capabilities will be described. Several real cases will be examined where results have shown justification for the use of a performance monitoring system.
A Variable-Geometry Power Turbine for Marine Gas Turbines
Authors: Karstensen Karl W. , Wiggins Jesse O.
Published: March 2015

Gas turbines have been accepted in naval surface ship applications, and considerable effort has been made to improve their fuel consumption, particularly at part-load operation. This is an important parameter for shipboard engines because both propulsion and electrical-generator engines spend most of their lives operating at off-design power. An effective way to improve part-load efficiency of recuperated gas turbines is by using a variable power turbine nozzle.

This paper discusses the successful use of variable power turbine nozzles in several applications in a family of engines developed for vehicular, industrial, and marine use. These engines incorporate a variable power turbine nozzle and primary surface recuperator to yield specific fuel consumption that rivals that of medium speed diesels. The paper concentrates on the experience with the variable nozzle, tracing its derivation from an existing fixed vane nozzle and its use across a wide range of engine sizes and applications. Emphasis is placed on its potential in marine propulsion and auxiliary gas turbines.
Fuel Molecular Structure and Flame Temperature Effects on Soot Formation in Gas Turbine Combustors
Authors: Gülder Ö. L. , Glavinčevski B. , Baksh M. F.
Published: March 2015

A systematic study of soot formation along the centerlines of axisymmetric laminar diffusion flames of a large number of liquid hydrocarbons, hydrocarbon blends, and aviation turbine and diesel fuels were made. Measurements of the attenuation of a laser beam across the flame diameter were used to obtain the soot volume fraction, assuming Rayleigh extinction. Two sets of hydrocarbon blends were designed such that the molecular fuel composition varied considerably but the temperature fields in the flames were kept practically constant. Thus it was possible to separate the effects of molecular structure and the flame temperature on soot formation. It was quantitatively shown that the smoke point height is a lumped measure of fuel molecular constitution. The developed empirical relationship between soot volume fractions and fuel smoke point and hydrogen to carbon ratio was applied to five different combustor radiation data, and good agreement was obtained.
Unsteady Transition in an Axial Flow Turbine: Part 2 — Cascade Measurements and Modelling
Authors: Addison J. S. , Hodson H. P.
Published: March 2015

Part 1 of this paper reanalysed previously published measurements from the rotor of a low speed, single stage, axial flow turbine which highlighted the unsteady nature of the suction surface transition process. Part 2 investigates the significance of the wake jet and the unsteady frequency parameter. Supporting experiments carried out in a linear cascade with varying inlet turbulence are described together with a simple unsteady transition model explaining the features seen in the turbine.
Engineering Design of Tough Ceramic Matrix Composites for Turbine Components
Authors: Tan T. M. , Pastore Christopher M. , Ko Frank K.
Published: March 2015

This paper provides a review of the material design concepts for the toughening of ceramic matrix composites by 3-D fiber architecture. To establish a communication link between the structural and the materials engineers, an integrated design methodology is presented with an example. Through a Fabric Geometry Model (FGM), the contribution of 3-D fiber architecture is translated into a stiffness matrix for finite element structural analysis. With the feedback from the structural analysis, this design methodology provides an effective means to screen reinforcement materials systems for 3-D fabric reinforced composite components.
The Influence of Boundary Layer State on Vortex Shedding From Flat Plates and Turbine Cascades
Authors: Sieverding C. H. , Heinemann H.
Published: March 2015

The paper aims at a better understanding of the reasons for the wide range of Strouhal numbers observed on turbine blades. The investigation is restricted to the subsonic domain. Firstly, flat plate model tests are carried out to investigate the effect of both the boundary layer state and trailing edge geometry on the vortex shedding frequency. A particular objective of the tests is to obtain data for the very common case of a mixed laminar-turbulent separation from turbine blades. These basic tests are followed by three cascade tests with blades of very different suction side velocity distributions. Based on the experience gained from the flat plate test program, an attempt is made to interprete the Strouhal number variation with Mach number and Reynolds number, and to relate the vortex frequency change to the boundary layer state on the blade surfaces.
Computation of the Flow Field and Heat Transfer in a Rectangular Passage With a Turbulator
Authors: Becker Bryan R. , Rivir Richard B.
Published: March 2015

A detailed numerical study of the aerothermal mechanics within a short straight section of a turbine blade internal cooling passage with a single turbulator is described. The two dimensional, transient, Reynolds averaged Navier Stokes, continuity and energy equations are iterated to a steady state solution using the MacCormack explicit predictor-corrector algorithm. Turbulence closure is achieved through the use of the Baldwin-Lomax algebraic two layer eddy viscosity model.

Axial distributions of local skin friction coefficient, local Stanton number and local Nusselt number are given. Profiles of velocity and temperature are presented as well as contours of streamfunction and temperature which display complex details of the flow structure. It was found that the widely used Reynolds Analogy greatly underpredicts the heat transfer rate as given by a direct calculation using Fourier’s law. Finally, the numerical results are found to compare favorably to the experimental results published by Han et al (1986).
Through Flow Theory for Nonaxisymmetric Turbomachinery Flow: Part II — Assessment
Authors: Dring Robert P. , Oates Gordon C.
Published: March 2015

Through flow theory has been limited in its applicability and in its accuracy by the fact that it has not historically been cast in a form which can account for the nonaxisymmetries that naturally arise in turbomachinery flow due to the presence of finite numbers of rotor and stator airfoils. The attempt to circumvent this limitation by the introduction of an aerodynamic blockage factor has been demonstrated in earlier work to produce fundamental inconsistencies in the calculation which lead to significant errors in the regions of the flow where the nonaxisymmetries are severe. The formulation in Part I of the present work is a derivation of a system of through flow equations for nonaxisymmetric flow.

A benchmark data base is used in Part II to provide input to the calculation and to help identify the dominant terms. It is demonstrated that the dominant effect of nonaxisymmetry is contained in two terms that relate the total pressure of the averaged flow to the mass averaged total pressure. It is also demonstrated that the present formulation produces a result which is more accurate than that obtained with the historical blockage-based formulation.
Stability of Flow Through Multistage Axial Compressors
Authors: Longley J. P. , Hynes T. P.
Published: March 2015

This paper describes measurements of the performance of a research stage operating in isolation and as part of a multistage compressor. It is shown that the stall point and the stalled performance of the stage are properties of the system in which it operates rather than a property of the stage itself. The consequences of this for the estimation of the stall point for compressors and compression systems are discussed. The support that the measurements give to assumptions made by mathematical models which use the concept of an ‘underlying axisymmetric’ characteristic are highlighted.
Three-Dimensional Incompressible Flow Solution of an Axial Compressor Using Pseudostream-Functions Formulation
Authors: Xu J. Z. , Shi J. C. , Ni W. Y.
Published: March 2015

Based on considering the characteristic features of the momentum equations and meeting the requirement of the continuity, two pseudostream-functions are introduced. The principal equation of each pseudostream-function only contains the terms of its own second-order partial derivatives and does not include the second-order partial derivatives of another pseudostream-function. So the relation between the two equations are loosed considerablly and both equations may be solved separately. This property is valueful to obtain the convergent solution of flow field easily. The equations of the pseudostream-functions and the corresponding boundary conditions are given. Two incompressible flow examples show that this method may become a powerful tool in the aerothermodynamic analysis and design of a compressor.
Automated Laser Welding of Turbine Airfoil Details
Authors: Gardner Bruce E. , Bartlett John M.
Published: March 2015

This presentation reviews the technical aspects of the Air Force-funded Turbine Airfoil Laser Welding Work Center at the Pratt & Whitney division of United Technologies Corporation. The center features automated tacking, welding, and visual inspection of covers, seals, and metering plates on turbine blades and vanes. In this integrated work center, productivity has increased by approximately 45 percent at a reduced cost compared to conventional methods. The types of automation/integration are described and the benefits are highlighted. The center was developed with U.S. Air Force funding under the Industrial Modernization Incentives Program (IMIP).
A New Analytical Model for Interpreting the Wear Mechanisms of Abradable Seal Systems and Verification by Testing
Authors: Soehngen J.
Published: March 2015

In order to minimize the specific fuel consumption of gas turbines it is necessary to increase the gas temperatures and pressure ratios. Therefore, new high-temperature resistant abradable seal systems must be developed, especially for the hot section. Since the required operating temperatures are above 1050°C, the use of metallic materials as abradables is out of the question. A problem commonly encountered in the selection of new (ceramic) materials for seal systems is that of insufficient knowledge of the tribological process occurring when turbine blades rub against an abradable seal.

The purpose of the investigation was to find a simplified analytical model to describe the tribological process occurring in the rubbing of the blades against the seal, in order to help in the preselection of materials for abradable seals. The model was verified by testing high-temperature resistant abradable seals under simulated engine conditions, followed by metallurgical examination. The results of the examination of two abradable seals on run engine components confirmed the analytical prediction and laboratory tests.

The differences in material loss from the blade and the abradable seal can be correlated to the heat flux distribution in the sliding parts. Using different materials on the blade tip and stationary seal (e.g. ceramic blade tip and ceramic or metallic abradable seal), the heat flux can be directed in such a way that the wear takes place largely on the static part of the engine. By calculating their relative abradability, material combinations with optimum performance for each seal application can be found.
The Development and Delivery of Expert Systems for Special Environments
Authors: Bloom Charles P. , Isle Brian A. , Butler Arch W.
Published: March 2015

The overall effectiveness of any expert system for maintenance and troubleshooting is a function of the knowledge applied to its problem-solving task and the delivery of that knowledge to the user (i.e., the interface between user and system). There is a direct relationship between how functional the user/system interface is and the degree to which users of the expert system can apply its capabilities to solve problems. In gas turbine troubleshooting and maintenance applications, it is often necessary to have access to documents such as schematics, electrical wiring diagrams, and equipment block diagrams, and to pictures of actual components themselves. Because these can be essential sources of information for a diagnostician, they should be included in any implementation of a system specifically designed to assist the user. In addition, the intended user’s mode of interaction with the system can vary within maintenance applications: Can the user interact with the system via a keyboard, or is voice input necessary? Can the user read a display, or is voice output necessary?
GATE: A Simulation Code for Analysis of Gas-Turbine Power Plants
Authors: Erbes M. R. , Gay R. R. , Cohn A.
Published: March 2015

The GATE (GAs Turbine Evaluation) code has been developed to evaluate the design and off-design performance of existing and advanced gas-turbine-based systems for power plant applications. By combining an intuitive, graphical user interface with detailed analytical models for the thermodynamic, heat-transfer and fluid-mechanical processes within gas-turbine-based power plants, GATE can be used by novices as well as experts for complex design and simulation studies. It can model a variety of gas turbine configurations and cooling technologies, and users can also interactively design and analyze an associated steam bottoming cycle. The basic formulations used in GATE are presented here, along with sample cases demonstrating the power and flexibility of the code.
The Properties and Characteristics of Electroless Nickel Coatings Applied to Gas Turbine Engine Components
Authors: Bleeks Thomas W. , Brindisi Frank
Published: March 2015

The improvement of reliability and reduction of overhaul time is of paramount importance to engineers involved with coatings used on gas turbine engine components. Aluminum/phosphate/chromate coatings are currently used in industrial and aircraft gas turbine engines for coating compressor components. Traditional electrolytic nickel with diffused cadmium coatings are also used but to a lesser extent. Field experience, however, has shown limitations with both coating systems, particularly in the areas of erosion, wear, and simplicity in component processability.

Currently, several new electroless nickel coatings are gaining significant acceptance in the industry, both for overhaul and repair, as well as for new part manufacture. This paper presents erosion, corrosion, fatigue and stress data on these coatings. Some field experience is also presented from airline operators and overhaul facilities who are incorporating these coatings on aircraft gas turbine engine components. Information is also given on the capability of electroless nickel coatings to reduce manufacturing cost and simplify the processing of complex parts.
Feasibility Study on Honeycomb Ceramics for Catalytic Combustor
Authors: Kawakami Takashi , Furuya Tomiaki , Sasaki Yukio , Yoshine Toshiyuki , Furuse Yutaka , Hoshino Mitsunobu
Published: March 2015

This paper contains results of a structural feasibility study on honeycomb ceramic materials used for catalytic combustors in power gas turbines. Extruded cordierite honeycomb substrates are widely used as catalyst carriers in automotive exhaust systems, because of their excellent thermal shock resistance. For gas turbines, however, the ceramic catalyst carriers should retain the reliability at high temperature.

In a hybrid catalytic combustor, which handles both catalysis and gas phases combustion, cordierite honeycomb structures (melt at 1445°C) can be adopted as the catalyst carrier, because the auxiliary gas phase combustion makes catalyst temperature lower than the conventional catalytic combustor.

During this study, cordierite honeycomb (200 square cells/in2) tensile tests were carried out at high temperatures up to 1000°C. Using the finite element method, stresses in a cell wall were analyzed. The honeycomb cell wall mechanical strength was derived by comparing the experimental and analytical results. Also, combustor honeycomb cell stresses were calculated under typical oprerating conditions. Consequently, it was shown that it is sufficiently feasible to use the cordierite honeycomb structure as a catalyst carrier for hybrid catalytic combustors.
Overview on Test Cases for Computation of Internal Flows in Turbomachines
Authors: Fottner Leonhard
Published: March 2015

Aero engine component design and development makes increasing use of computer codes for flow field calculations, such as two- or three-dimensional flow fields and flow fields with strong viscous effects. The accuracy of these calculation methods depends on the mathematical models and numerical schemes used to describe the physical reality. The proof of validity and the refinement of such methods depend on verification against relevant test cases, primarily experimental test cases. The AGARD Propulsion and Energetics Panel established Working Group 18 to specify relevant reference test cases to serve as validation bases for new methods, but also as check for existing production codes. The present paper gives an overview on the results of the Working Group and briefly describes the different test cases. These test cases refer to analytical and experimental test cases for steady flow in linear compressor and turbine cascades, single blade rows, single and multistage axial compressors and turbines and ducts. In addition, suggestions for future tests designed to reduce the limitations are discussed.
3D Mean-Stream-Line Method: A New Engineering Approach to the Inverse Problem of 3D Cascade
Authors: Gong Yifang , Cai Ruixian
Published: March 2015

The Mean-Stream-Line Method proposed by Wu and Brown (1952) for 2D cascade is developed and extended to solve the 3D inverse problem of turbomachine flow. The equations suitable to the 3D case are derived and the well-posed design conditions are discussed within the scope of the annular wall constraint of turbomachines mentioned by Cai (1983). A computer code has been programmed for this method and computation results compare well with 3D incompressible potential analytical solutions. These solutions, discovered by Cai et al. (1984), are similar to turbomachine flow. A comparison of computation results between this method and the conventional 3D potential function method is also presented. However, in solving the inverse problem, the 3D Mean-Stream-Line Method is much more simple and faster than all other methods already available. In addition, some ideas to solve direct and hybrid problems are also suggested.
Flow in a Centrifugal Fan of the Squirrel Cage Type
Authors: Kind R. J. , Tobin M. G.
Published: March 2015

This paper presents the results of performance measurements and detailed measurements of the mean flow field at rotor inlet and rotor exit in three squirrel cage fan configurations. The flow-field measurements were taken with a five-hole probe and yield total pressure, static pressure and the three components of velocity. Measurements were taken for two casing throat areas and for two different rotors. For each configuration the flow field was measured for flow rates below, near and above the best-efficiency point. Flow patterns are complex and there is reverse flow through the rotor blading even at the best-efficiency operating condition. Although complex, the main features of flow behaviour can be understood. They were common to all three fan configurations.
Development of the Tip-Leakage Flow Downstream of a Planar Cascade of Turbine Blades: Vorticity Field
Authors: Yaras M. , Sjolander S. A.
Published: March 2015

The paper presents detailed measurements of the tip-leakage flow emerging from a planar cascade of turbine blades. Four clearances of from 1.5 to 5.5 percent of the blade chord are considered. Measurements were made at the trailing edge plane, and at two main planes 1.0 and 1.56 axial chord lengths downstream of the cascade. The results give insight into several aspects of the leakage flow including: the size and strength of the leakage vortex in relation to the size of the tip gap and the bound circulation of the blade; and the evolution of the components of vorticity as the vortex diffuses laterally downstream of the blade row. The vortex was found to have largely completed its roll-up into a nearly axisymmetric structure even at the trailing edge of the cascade. As a result, it was found that the vortex could be modelled surprisingly well with a simple model based on the diffusion of a line vortex.
Application of Recess Vaned Casing Treatment to Axial Flow Fans
Authors: Azimian A. R. , Elder R. L. , McKenzie A. B.
Published: March 2015

The effect of applying a vaned recessed casing treatment to a single stage axial flow fan has been investigated. The influence of the axial position of the recess relative to the rotor leading edge and other geometrical modifications of the vane passage have been examined. Significant improvements in stall margin were observed without (in some builds) loss in peak efficiency.

Slow and fast frequency response yawmeter probes have been used in the study to examine both the steady flow conditions and the unsteady flow caused by rotating stall.
An Approximate 3-D Aerodynamic Design Method for Centrifugal Impeller Blades
Authors: Xiaolu Zhao , Lisen Qin
Published: March 2015

An aerodynamic design method, which based on the Mean Stream Surface Method (MSSM), has been developed in designing the centrifugal compressor impeller blades. As a component of a CAD system for centrifugal compressor, it is convenient to use the presented method for generating impeller blade geometry, taking care of manufacturing as well as aerodynamic aspects.

The design procedure starts with an S2m indirect solution. Afterwards from the specified S2m surface, by the use of Taylor series expansion, the blade geometry is generated by straight-line elements to meet the requirement of manufacture. Simultaneously, the fluid dynamic quantities across the blade passage, can be determined directly. In terms of these results, the designer can revise the distribution of angular momentum along the shroud and hub, which are associated with blade loading to get satisfactory velocities along the blade surfaces in order to avoid or delay flow separation.
Three-Dimensional Separated Flow Field in the Endwall Region of an Annular Compressor Cascade in the Presence of Rotor-Stator Interaction: Part II — Unsteady Flow and Pressure Field
Authors: Schulz H. D. , Gallus H. E. , Lakshminarayana B.
Published: March 2015

An experimental study of the unsteady three-dimensional flow and pressure field in an annular compressor cascade with an upstream rotor has been carried out at several incidences to the stator blade. The distribution of the unsteady pressures at the blade surfaces are measured using fast response Kulite sensors. The unsteady blade boundary layers and the passage flow is measured with a hot wire sensor. Detailed interpretation of the magnitude of unsteady pressures, phase angle differences, unsteady blade boundary layers, wake transport through the stator passage is presented and analyzed in the paper. The unsteady pressures are found to be dominant near the blade leading edge. Substantially higher pressure fluctuations occur in this region as well as on the edge of the corner flow separation region.
Effects of Tip Clearance of Nozzle Vanes on Performance of Radial Turbine Rotor
Authors: Hayami H. , Hyun Y. I. , Yamaguchi M. , Senoo Y.
Published: March 2015

In radial turbines with variable nozzles, the flow downstream of the nozzles could be distorted by the leakage flow through the tip-clearance of the upstream nozzle vanes. To investigate the effects of flow distortion on the performance of turbine rotors, two rotors with different number of blades were tested for three types of distorted velocity distributions at the rotor inlet. In the case of the 20 blade rotor with moderate blade loading, the flow distortion at the rotor inlet had negligible effect on the rotor characteristics, and the measured data on the turbine performances agreed well with a prediction. Predictions were made with a conventional one-dimensional flow model applied to the rotor flow while a two-layer flow model was applied to the flow in the nozzle with clearance. In the case of the 10 blade rotor with heavy blade loading, however, the rotor performance was found to be sensitive to the inlet flow distortion and was considerably lower than the prediction.
The Preliminary Design of Radial Inflow Turbines
Authors: Whitfield A.
Published: March 2015

A procedure is described which develops the non-dimensional design of a radial inflow turbine rotor. The design is developed, for any specified non-dimensional power ratio, with the objective of minimising the inlet and discharge Mach numbers so that the passage losses are minimised. Initially state of the art efficiencies are assumed but are later modified through the specification of empirical losses. The resultant non-dimensional design can be transformed to absolute dimensions through the specification of the inlet stagnation conditions and the mass flow rate of the working fluid.
Pressure Loss and Heat Transfer in Channels Roughened on Two Opposed Walls
Authors: Mayle R. E.
Published: March 2015

In order to selectively increase cooling effectiveness, coolant channels in gas turbine components are often only roughened on one or two walls of the channel. A model is presented for flow in rectangular channels having two opposed roughened walls and a theory is developed for both the pressure loss and heat transfer. The theory allows one to calculate the heat transfer coefficient on each wall separately in addition to the overall friction factor and heat transfer coefficient. Comparisons are made to data for similarly configured channels, tubes and surfaces roughened by regularly spaced transverse ribs placed normal to the flow direction. Correlations for the displacement velocity in the logarithmic law and the roughness Stanton number in terms of the rib pitch-to-height ratio and roughness Reynolds number are also presented.
Incremental Fuel Cost Prediction for a Gas Turbine Combined Cycle Utility
Authors: Little D. , Nikkels H. , Smithson P.
Published: March 2015

For a medium sized (300 MW) utility producing electricity from a 130 MW combined cycle, and supplemental 15 MW to 77 MW capacity simple cycle gas turbines, the incremental fuel costs accompanying changes in generating capacity vary considerably with unit, health, load level, and ambient. To enable incremental power to be sold to neighbouring utilities on an incremental fuel cost basis, accurate models of all gas turbines and the combined cycle were developed which would allow a realistic calculation of fuel consumption under all operating conditions. The fuel cost prediction program is in two parts; in the first part, gas turbine health is diagnosed from measured parameters; in the second part, fuel consumption is calculated from compressor and turbine health, ambient conditions and power levels.

The paper describes the program philosophy, development, and initial operating experience.
Endwall Heat Transfer in a Vane Cascade Passage and in a Curved Duct
Authors: Boyle M. T. , Hoose K. V.
Published: March 2015

Measurements of endwall heat transfer coefficient have been made for flow through a vane cascade passage and a similarly shaped duct. The purpose of this work is to evaluate the usefulness of the duct shape for modelling cascade endwall heat transfer. The Reynolds number for the cascade experiment is 5.4 × 105 based on chord. For the duct geometry the inlet velocity is adjusted in order to match the Reynolds number based on the pitch dimension. Thin stainless steel strips mounted on the endwall make up a large flat resistance heater. The temperature distribution over the heater surface is measured with 156 resistance temperature sensors. Surface heat transfer coefficient is obtained in the vicinity of each sensor by a local energy balance. The results are presented so as to show clearly the effect of secondary flow on endwall heat transfer. Except in the entrance plane region, the qualities of the cascade endwall Stanton number distribution compare well with the duct endwall measurements. The duct endwall heat transfer coefficients are everywhere greater than for the cascade passage endwall. The effect of a counter-clockwise rotating vortex in the suction side corner is shown clearly for both geometries.
On-Line Compressor Washing Practices and Benefits
Authors: Thames J. M. , Stegmaier J. W. , Ford John J.
Published: March 2015

Compressor washing is a common gas turbine maintenance task. This paper presents results from field surveys of gas turbine users, manufacturers, and washing agent suppliers. These surveys were conducted to assess current washing practices and needs for various user applications. Plans for field testing to evaluate performance and effectiveness of on-line washing are also presented.
Expanding Expertise With State-of-the-Art Monitoring
Authors: Gramatikas George F. , Davis Daniel L.
Published: March 2015

This paper describes a program that groups gas turbines from one or more sites for the purpose of efficient monitoring and performance evaluation. Cost-improved gas turbine and power plant operation is achieved by a new, unified-yet-flexible service approach which combines state-of-the-art microprocessor-based monitoring with routine and emergency evaluation by a core of highly skilled personnel many miles from the operating site.

This unique approach delivers expertise which supplements the gas turbine owner’s in-house resources. It is based on a modular concept of condition health monitoring and performance evaluation, including scheduled as well as on-line services. Portable condition health monitoring equipment provides the capability for scheduled plant performance evaluation by service engineers without investment in additional equipment. On-line monitoring includes a PC-based software system and a computer link to the service engineer’s headquarters. Both scheduled and on-line monitoring services include trend evaluation, projected maintenance requirements, maintenance planning assistance and suggestions for performance enhancement.
Effect of Rib-Angle Orientation on Local Mass Transfer Distribution in a Three-Pass Rib-Roughened Channel
Authors: Han J. C. , Zhang P.
Published: March 2015

In this experimental investigation of the heat transfer characteristics of turbulent air flow in a three-pass square channel, the test section consisted of three straight square channels jointed by two 180° turns, modeling the internal cooling passages of gas turbine airfoils. Naphthalene-coated ribs were attached to the top and the bottom walls of the naphthalene-coated, three-pass channel. The rib height-to-hydraulic diameter ratio was 0.063; the rib pitch-to-height ratio was 10; the rib angles were 90° and 60°. For α = 60°, both the crossed ribs (on two opposite walls of the cooling channel) and the parallel ribs (on two opposite walls of the cooling channel) were investigated. The combined effects of the two sharp 180° turns and the rib orientations on the distributions of the local mass transfer coefficient in the entire three-pass channel were determined.

The rib angle, the rib orientation, and the sharp 180° turn significantly affect the local mass transfer distributions. The combined effects of these parameters can increase or decrease the mass transfer coefficients after the sharp 180° turns. The angled ribs, in general, provide higher mass transfer coefficients than the transverse ribs; the parallel ribs give higher mass transfer than the crossed ribs.
Energy Considerations in Twin-Fluid Atomization
Authors: Lefebvre Arthur H.
Published: March 2015

With certain types of prefilming airblast atomizers, the manner in which the atomizing air impinges on the liquid sheet prohibits the wave formation that normally precedes the breakup of a liquid sheet into drops. Instead, the liquid is shattered almost instantaneously into drops of various sizes. This prompt atomization process is characterized by a broad range of drop sizes in the spray and by a lack of sensitivity of mean drop size to variations in liquid viscosity, atomizing air pressure, and initial liquid sheet thickness. Evidence is presented to show that which of these two different modes of atomization will occur in any given flow situation is largely dependent on the angle at which the atomizing air impinges on the liquid sheet. An equation for mean drop size, derived from the assumption that the main factor controlling prompt atomization is the ratio of the energy required for atomization to the kinetic energy of the atomizing air, is shown to provide a good fit to experimental data acquired from atomization studies on water and heating oil, carried out over wide ranges of air velocity, air/liquid ratio, and ambient air pressure.
Experimental Study on Internal Mixing Sonic Flow Air Assist Atomizer for Heavy Oils
Authors: Chin Ju Shan , Wang Li Xing
Published: March 2015

Based on the experiences previously obtained from the experimental study of plain jet atomization under cross flowing air stream and under supersonic air flow, the authors designed and studied a serious of internal mixing sonic flow air assist atomizers for heavy oil application. The contradiction between the requirements for fine spray (for high combustion completeness) and for long flame (for flame rigidity) often existing in industrial furnace has been solved. Good data were obtained which can be used for the design of such kind atomizers. By properly choosing the configuration and geometrical dimensions of the atomizer, also by choosing suitable values for mixing chamber pressure, air–liquid ratio, it is possible to have very fine spray and desirable flame length. The results showed that the ratio of mixing chamber pressure to air supply pressure should be in the range of 0.6 to 0.7. For atmospheric pressure combustion furnace, such air assist atomizer needs 0.4 MPa compressed air to have sonic flow at nozzle exit. This type of air assist atomizer has already been put into industrial operation.
Experimental Evaluation of Sorbents for Sulfur Control in a Coal-Fueled Gas Turbine Slagging Combustor
Authors: Cowell L. H. , Wen C. S. , LeCren R. T.
Published: March 2015

A slagging combustor has been used to evaluate three calcium-based sorbents for sulfur capture efficiency in order to assess their applicability for use in a coal-fueled gas turbine. Testing is completed in a bench-scale combustor with one-tenth the heat input needed for the full-scale gas turbine. The bench-scale rig is a two-staged combustor featuring a fuel rich primary zone and a fuel lean secondary zone. The combustor is operated at 6.5 bars with inlet air preheated to 600 K. Gas temperatures of 1840 K are generated in the primary zone and 1280 K in the secondary zone. Sorbents are fed in either the secondary zone or mixed with the coal water mixture and fed into the primary zone. Dry powdered sorbents are fed into the secondary zone by an auger into one of six secondary air inlet ports. The three sorbents tested in the secondary zone include dolomite, pressure hydrated dolomitic lime, and hydrated lime. Sorbents have been tested while burning coal water mixtures with coal sulfur loadings of 0.56 to 3.13 weight percent sulfur. Sorbents are injected into the secondary zone at varying flow rates such that the calcium/sulfur ratio varies from 0.5 to 10.0. Hydrated lime exhibits the highest sulfur dioxide reductions in the exhaust of 90%. Pressure hydrated dolomitic lime and dolomite reduce SO2 concentrations by 82% and 55%, respectively. Coal sulfur loading is found to have a small influence on sorbent sulfur capture efficiency. Pressure hydrated dolomitic lime ground with the coal during coal water mixture preparation and injected into the primary zone is found to lower the sulfur dioxide concentration by an insignificant amount.