bluuebunny/crossref_metadata_2025 huggingface dataset:
Unsteady Pressure Measurements in a Rotating Centrifugal Impeller
Authors: Roth G.
Published: March 2015

The design of a shrouded radial test impeller which enables the application of miniature pressure transducers inside the blades is presented. An explanation of the measurement and analysis technique is given. The results of suction side blade surface pressure measurements at several points of a performance line are presented. Two different types of diffuser rotating stall were detected. The pressure behaviour at impeller stall and surge inception is demonstrated. Furthermore, the periodic engine order blade surface pressure signals at a stable operating point are shown.
Techniques for Aerodynamic Loss Measurement of Transonic Turbine Cascades With Trailing-Edge Region Coolant Ejection
Authors: Mee D. J.
Published: March 2015

Experimental techniques associated with the measurement of loss of transonic turbine blades with trailing-edge region coolant ejection are considered. Results from experiments with different coolant to free stream gas density ratios indicate that it is not always adequate to simulate only the coolant blowing rate. However, for the measurement of loss, the present experimental results indicate that it may be adequate to simulate the momentum flux ratio. In loss calculations the value used for the total pressure of the coolant gas is discussed and shown to influence a comparison of different cooling geometries.
Computational Techniques for Probabilistic Analysis of Turbomachinery
Authors: Millwater H. R. , Smalley A. J. , Wu Y.-T. , Torng T. Y. , Evans B. F.
Published: March 2015

This paper reports on some advanced computational techniques for probabilistic analysis of turbomachinery. A description of the requirements for probabilistic analysis and several solution methods are summarized. The traditional probabilistic analysis method, Monte Carlo simulation, and two advanced techniques, the Advanced Mean Value (AMV) method and importance sampling, are discussed.

The performance of the Monte Carlo, AMV, and importance sampling methods is explored through a forced response analysis of a two degree-of-freedom Jeffcott rotor model. Variations in rotor weight, shaft length, shaft diameter, Young’s modulus, foundation stiffness, bearing clearance, viscosity, and length are considered. The cumulative distribution function of transmitted force is computed using Monte Carlo simulation and AMV at several RPM. Also, importance sampling is used to compute the probability of transmitted force exceeding a specified limit at several RPM. In both cases, the AMV and importance sampling methods are shown to give accurate solutions with far fewer number of simulations than the Monte Carlo method. These methods enable the engineer to perform accurate and efficient probabilistic analysis of realistic complex rotor dynamic models.
Advances in the Numerical Integration of the 3-D Euler Equations in Vibrating Cascades
Authors: Gerolymos Georg A.
Published: March 2015

In the present work an algorithm for the numerical integration of the 3-D unsteady Euler equations in vibrating transonic compressor cascades is described. The equations are discretized in finite-volume formulation in a mobile grid using isoparametric brick elements. They are integrated in time using Runge-Kutta schemes. A thorough discussion of the boundary-conditions used and of their infuence on results is undertaken. The influence of grid refinement on computational results is examined. Unsteady convergence of results is discussed.
Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 1 — Forcing Functions
Authors: Henderson Gregory H. , Fleeter Sanford
Published: March 2015

The fundamental gust modeling assumption is investigated by means of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady periodic flow field is generated by rotating rows of perforated plates and airfoil cascades. In this paper, the measured unsteady flow fields are compared to linear-theory gust requirements, with the resulting unsteady gust response of a downstream stator cascade correlated with linear theory predictions in an accompanying paper. The perforated-plate forcing functions closely resemble linear-theory forcing functions, with the static pressure fluctuations small and the periodic velocity vectors parallel to the downstream mean-relative flow angle over the entire periodic cycle. In contrast, the airfoil forcing functions exhibit characteristics far from linear-theory gusts, with the alignment of the velocity vectors and the static pressure fluctuation amplitudes dependent on the rotor-loading condition, rotor solidity and the inlet mean-relative flow angle. Thus, these unique data clearly show that airfoil wakes, both compressor and turbine, are not able to be modeled with the boundary conditions of current state-of-the-art linear unsteady aerodynamic theory.
Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 2 — Low Solidity Airfoil Row Response
Authors: Henderson Gregory H. , Fleeter Sanford
Published: March 2015

The fundamental gust modeling assumption is investigated by means of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady periodic flow field is generated by rotating rows of perforated plates and airfoil cascades, with the resulting unsteady periodic chordwise pressure response of a downstream low solidity stator row determined by miniature pressure transducers embedded within selected airfoils. When the forcing function exhibited the characteristics of a linear-theory gust, as was the case for the perforated-plate wake generators, the resulting response on the downstream stator airfoils was in excellent agreement with the linear-theory models. In contrast, when the forcing function did not exhibit linear-theory gust characteristics, i.e., for the airfoil wake generators, the resulting unsteady aerodynamic response of the downstream stators were much more complex and correlated poorly with the linear-theory gust predictions. Thus, this investigation has quantitatively shown that the forcing function generator significantly affects the resulting gust response, with the complexity of the response characteristics increasing from the perforated-plate to the airfoil-cascade forcing functions.
Applications of Sweep Frequency Rotating Force Perturbation Methodology in Rotating Machinery for Dynamic Stiffness Identification
Authors: Muszynska Agnes , Bently Donald E. , Franklin Wesley D. , Grant John W. , Goldman Paul
Published: March 2015

This paper outlines the sweep frequency rotating force perturbation method for identifying the dynamic stiffness characteristics of rotor/bearing/seal systems. Emphasis is placed on nonsynchronous perturbation of rotating shafts in a sequence of constant rotative speeds. In particular, results of the identification of flexible rotor multi–mode parameters and identification of fluid forces in seals and bearings are given. These results, presented in the direct and quadrature dynamic stiffness formats, permit the separation of components for easy identification. Another example of the perturbation method application is the identification of the lateral–torsional coupling due to shaft anisotropy. Results of laboratory rig experiments, the identification algorithm, and data processing techniques are discussed.
Tools for Diagnosing Case Deflections and Alignment on a Power Utility Combustion Turbine
Authors: Simmons Harold R. , Smalley Anthony J. , Frischmuth Robert W. , Lapini Gianluca , Robinson George
Published: March 2015

This paper discusses development, installation, and analysis of instrumentation systems for reliably measuring casing, thermal distortion, and alignment deviation on a large combustion turbine in power utility service. A variety of redundant measurement systems were installed to document casing distortion during the cool-down period after firing. The operating principles of each measurement system are described and presented with the rationale developed for installing and locating sensors. A vertical deflection sensor used for casing bow and bearing misalignment measurement is highlighted in the paper to illustrate its potential for use in other investigations. Additional sensors used include an array of shaft proximity probes, blade tip proximity probes, thermocouples, and axial growth probes. A measurement system for casing ovalization was developed using LVDT’s mounted from a thermally stabilized ring. An automated data acquisition system was developed and installed to facilitate the recording of turbine cool-down events over the complete operating season without the need for constant on-site attention. Preliminary results define the turbine cylinder bow and ovalization response during the cool-down event following normal unit operation and correlated casing distortions with thermal gradients.
Behaviors of the Laterally Injected Jet in Film Cooling: Measurements of Surface Temperature and Velocity/Temperature Field Within the Jet
Authors: Honami Shinji , Shizawa Takaaki , Uchiyama Atsushi
Published: March 2015

This paper presents the behaviors of the injected jet on the flat surface in lateral injection of the film-cooling. Simultaneous velocity and temperature measurements were made by the double-wire probe. The test surface was also covered with an encapsulated temperature-sensitive liquid crystal. The image processing system based on the temperature and hue of the liquid crystal calibration provides the surface temperature distributions. The tests were conducted at three kinds of mass flux ratio of 0.5, 0.85, and 1.2. The laterally injected jet has an asymmetric structure with a large scale of vortex motion in one side caused by the interaction with the primary stream. Asymmetry is promoted with mass flux ratio increased, resulting in low film-cooling effectiveness.
Evaluation of Approaches to Active Compressor Surge Stabilization
Authors: Simon J. S. , Valavani L. , Epstein A. H. , Greitzer E. M.
Published: March 2015

Recent work has shown that compression systems can be actively stabilized against the instability known as surge, thereby realizing a significant gain in system mass flow range. Ideally, this surge stabilization requires only a single sensor and a single actuator connected by a suitable control law. Almost all research to date has been aimed at proof of concept studies of this technique, using various actuators and sensor combinations. In contrast, the work reported herein can be regarded as a step towards developing active control into a practical technique. In this context, the paper presents the first systematic definition of the influence of sensor and actuator selection on increasing the range of stabilized compressor performance. The results show that proper choice of sensor as well as actuator crucially affects the ability to stabilize these systems, and that, overall, those actuators which are most closely coupled to the compressor (as opposed to the plenum or throttle) appear most effective. In addition, the source of the disturbances driving the system (for example, unsteady compressor pressure rise or unsteady combustor heat release) has a strong influence on control effectiveness, as would be expected for a controls problem of this type. This paper both delineates general methodologies for the evaluation of active compressor stabilization strategies and quantifies the performance of several approaches which might be implemented in gas turbine engines.
Experimental Heat Transfer Investigation of Stationary and Orthogonally Rotating Asymmetric and Symmetric Heated Smooth and Turbulated Channels
Authors: El-Husayni H. A. , Taslim M. E. , Kercher D. M.
Published: March 2015

An experimental investigation was conducted to determine the effects of variations in wall thermal boundary conditions on local heat transfer coefficients in stationary and orthogonally rotating smooth wall and two opposite-wall turbulated square channels. Results were obtained for three distributions of uniform wall heat flux: asymmetric, applied to the primary wall only; symmetric, applied to two opposite walls only; and fully-symmetric, applied to all four channel walls. Measured stationary and rotating smooth channel average heat transfer coefficients at channel location L/Dh = 9.53 were not significantly sensitive to wall heat flux distributions. Trailing side heat transfer generally increased with Rotation number whereas the leading wall results showed a decreasing trend at low Rotation numbers to a minimum and then an increasing trend with further increase in Rotation number. The stationary turbulated wall heat transfer coefficients did not vary markedly with the variations in wall heat flux distributions. Rotating leading wall heat transfer decreased with Rotation number and showed little sensitivity to heat flux distributions except for the fully-symmetric heated wall case at the highest Reynolds number tested. Trailing wall heat transfer coefficients were sensitive to the thermal wall distributions generally at all Reynolds numbers tested and particularly with increasing Rotation number. While the asymmetric case showed a slight deficit in trailing wall heat transfer coefficients due to rotation, the symmetric case indicated little change whereas the fully-symmetric case exhibited an enhancement.
Scaling of the Two-Phase Flow Downstream of a Gas Turbine Combustor Swirl Cup: Mean Quantities
Authors: Wang H. Y. , McDonell V. G. , Sowa W. A. , Samuelsen G. S.
Published: March 2015

A production gas turbine combustor swirl cup and a 3x-scale model, both featuring co-axial, counter-swirling air streams are characterized at atmospheric pressure and in the absence of reaction. Spatially-resolved measurements of continuous phase (gas in the presence of spray) and droplet size and velocity are acquired downstream of the production and 3x-scale swirl cups by using two-component phase Doppler interferometry. The effect of scale on the behavior of the continuous phase and droplets is investigated by comparing the continuous phase velocity and droplet size and velocity at geometrically analogous positions. The continuous phase flow field scales well at the exit of the swirl cup. Farther downstream, differences occur which are due to disparity in entrainment. The droplet velocities scale reasonably well, but the sizes show some differences. However, the difference in size is less significant than it is between the two atomizers in the absence of the swirl cup assemblies.
What Affects the Cost of Hot Gas Filter Stations?
Authors: Zievers J. F. , Eggerstedt P. , Zievers E. C. , Nicolai D.
Published: March 2015

This technical paper examines the various aspects of hot gas filter station design which ultimately affect both initial and operational costs. Process conditions such as temperature and pressure, and design constraints such as face velocity are discussed with respect to their bearing on filter station costs. More subtle parameters such as pulse gas cleaning requirements and filter element geometry also directly impact filter design and hence, cost. As all of the information presented is based upon actual filter applications, it will provide useful insight for those involved in filter designing and recommendations.
Experimental Verification of the Improvements Achieved by a New LP-Blade Design in a Steam Turbine
Authors: Stetter H. , Eyb G. , Zimmermann C. , Hosenfeld H.-G.
Published: March 2015

In order to verify the improvements in the understanding of the flow in turbomachinery, extensive investigations were carried out at the LP-steam turbine at the University of Stuttgart. This paper initially focuses on the specific measuring technique in steam turbines with respect to problems of condensation. The stator wakes, noticeable in all measuring planes of the stage, require the determination of the flow vector over a large portion of the cross-section to obtain representative values. The application of a newly designed last stage for LP-steam turbines, which is characterized by curved guide-vanes, led to considerable improvements of the flow over the entire range of operation. The results gained by measurements on that stage are compared to former measurements on a stage version with straight guide-vanes. A significant change of flow characteristics over the blade span can be noticed. Particularly, the flow in the hub region was improved by balancing the radial pressure distribution.
The Quantitative Visualisation of the Flow in a 1/10th Scale Model Thrust Reverser at the Aircraft Research Association, Bedford
Authors: Bryanston-Cross P. , Sale R.
Published: March 2015

A series of laser visualisation measurements has been made to both visualise and map the velocity and direction of the transonic flow from a 1/10th scale model of a thrust reverser. The measurements which have been made by injecting micron sized water droplets into the flow, used two techniques to provide a quantitative measurement of the flow field.

The first technique LLS (laser light sheet) provided a general view of the flow, whereas a second pulse laser technique PIV (particle image velocimetry) made a specific measurement in the vicinity of the thrust reverser’s ‘kicker’ plate to map the velocity and direction of the exit flow.

This successful study is, to the best of the author’s knowledge, the first example of a whole field quantitative visualisation being achieved in such a turbulent transonic flow.
Heat Transfer and Aerodynamics of a High Rim Speed Turbine Nozzle Guide Vane With Profiled End Walls
Authors: Chana K. S.
Published: March 2015

It has been shown that the secondary flows present within turbine nozzle guide vanes have a marked effect on heat transfer. The horse-shoe and passage vortices, for example, have a major impact on platform and vane suction surface heat transfer. To investigate these effects further, heat transfer and aerodynamic measurements have been made on an annular transonic turbine nozzle guide vane ring, with three different platform geometries. The measurements were taken in the Isentropic Light Piston test facility at RAE Pyestock at representative values of engine Reynolds number, Mach number and freestream gas-to-wall temperature ratio.

This paper compares and discusses the measured platform and vane suction surface Nusselt and Mach number distributions for the three different endwall profiles. Comparisons with theoretical flow and heat transfer predictions are presented.
Measurements of the Effect of Free-Stream Turbulence Length Scale on Heat Transfer
Authors: Moss R. W. , Oldfield M. L. G.
Published: March 2015

The effects of free-stream turbulence scale on heat transfer through a turbulent flat plate boundary layer have been measured. A variety of turbulence spectra were produced by parallel bar grids. The design of these was guided by previous measurements of combustion chamber turbulence. Heat transfer was measured transiently using thin film gauges. The heat transfer to the plate was found to be a function of turbulence integral length scale as well as intensity, and is of relevance to gas turbine heat transfer where aerofoils are subject to high turbulence levels from the combustor. Enhancement factors of up to 40% were experienced and the results extend conclusions drawn by other workers to higher turbulence levels and scales.
Overview of the Japanese National Project for Super/Hyper-Sonic Transport Propulsion System
Authors: Ichimaru Osamu , Ishizuka Makoto , Muhashima Kanji
Published: March 2015

The Agency of Industrial Science and Technology (AIST), MITI of Japan, started research and development on a super/hypersonic transport propulsion system in FY1989 as an eight year project. The project, forecasting a flight cruise capability of up to Mach 5, aims at establishing basic technologies for an engine that combines a ramjet engine and a high performance turbojet engine. This paper presents the background, objective, organization, contents, etc., of this national project.
Development of a Direct Coal-Fired Combined Cycle for Commercial Application
Authors: Bannister R. L. , Wiant B. C. , Diehl R. C. , Eppich H. M. , Jensen A. R. , Mach F. V. , Claeson E. U. , Raatikka L. M. , Newby R. A.
Published: March 2015

A program has been underway since 1986 by Westinghouse Electric Corporation, Textron, Inc., and the sponsoring agency, the Morgantown Energy Technology Center (METC) of the U.S. Department of Energy (DOE), as participants, to establish the technology base for coal-fired combustion turbines targeted for power generation (50 to 150 MW size units). The developed system must be able to burn unbeneficiated, low-cost, utility-grade coal and meet the EPA New Source Performance Standards (NSPS) for coal-fired steam generators (Thoman et al., 1987).

Development of a high pressure (12 to 16 atms) slagging combustor is the key to making a direct coal-fired combustion turbine a commercial reality. In testing to date, a 6 atm slagging combustor, rated at 12 MMBtu/hr (12.7 MHkJ/hr) has demonstrated its ability to handle high- and low-sulfur bituminous coals, and low-sulfur subbituminous coal. The program objectives relative to combustion efficiency, combustor exit temperature and pattern factor, NOx emissions, carbon burnout, and slag rejection have been met.

Today, Northern States Power, working with Westinghouse with assistance from Textron is developing a plan to commercialize a direct coal-fired advanced combined cycle (DCFACC). Included in this plan is a pilot plant (which does not include a combustion turbine) and a demonstration plant that would utilize a 50 MW combustion turbine. The first commercial DCFACC, which would Include a 100 MW combustion turbine, is scheduled to be operational by the year 2001. The cooperative effort among Northern States Power, Westinghouse, and Textron is financially independent of the work now sponsored by DOE/METC.

This paper presents the status of the pressurized slagging combustor development program including recent work to reduce alkali, particulates and SOx levels leaving the combustor and gives an overview of our commercialization process and plan.
Experience With the Commissioning of a Natural Gas Power Recovery Turbine
Authors: Stoll Herbert
Published: March 2015

For major users of natural gas whose consumption of gas remains constant on annual average, it may be economical to recover pressure energy in a power recovery turbine instead of destroying it by throttling the gas line pressure to the level of the supply system.

Dortmunder Stadtwerke AG, a municipal power and transport utility at the eastern end of the Ruhr engaged RWTUV to provide consultancy and inspection services for the commissioning of such an installation and to conduct performance tests on all machine components.

The special features of the control behaviour of the installation during flow-rate-oriented operation of the turbine are to be dealt with in this paper. This will be done from the point of view of a throttle-loss-free flow, as far as achievable, into the nozzle groups through the turbine inlet valves. The features of control behaviour during startup and in the case of load changes with regard to heat supply using unit cogeneration plant modules will also be looked at.

Furthermore a report will be given on the special features of the performance test.
Prediction of 2D Viscous Transonic Flow in Compressor Cascades Using a Semi-Empirical Shock/Boundary-Layer Interaction Method
Authors: Hoeger M. , Broichhausen K. D.
Published: March 2015

A fast and robust calculation method for turbulent shock boundary-layer interaction is presented which enables the design engineer in quickly estimating the boundary-layer behaviour of a transonic compressor profile section. The separated flow in the vicinity of a shock is described in terms of the boundary-layer properties ahead of the shock and the shock strength itself. The method is incorporated in an integral boundary-layer procedure and coupled with the Euler-equations by the equivalent source concept. Calculations for the flow in transonic and supersonic compressor cascades demonstrate the ability of the present method and show good agreement with boundary-layer properties and Mach number distributions obtained from measurements.
A PC-Based Inverse Design Method Applied to Radial Inflow Turbines
Authors: Skoe Ivar Helge
Published: March 2015

The method described herewith is an ‘engineering’ approach to the inverse design problem where both aerodynamic and mechanical criteria are imposed. A novel exducer configuration, with slanted trailing edge, evloves during the iterative design procedure based on the introduction of:

- a realistic loss distribution

- a prescribed rotor exit spanwise total pressure distribution

- and with the imposed geometric restrictions.

For a Gas Generator Turbine, ‘back-to-back’ traverse results show reduced loss for the novel design as compared with a conventionally designed Radial Inflow Turbine.

Through extensive use of ‘Bezier Curves’ for the aerodynamically defined 3-D geometry, the same ‘solid model’ is used to prepare the input files for the structural analysis (’meshing’ for the FEM) as well as the geometry definition for production.
A Viscous Axisymmetric Throughflow Prediction Method for Multi-Stage Compressors
Authors: Ucer Ahmet S. , Shreeve Raymond P.
Published: March 2015

This paper describes a computer code which solves viscous axisymmetric flow through multistage compressors. The code incorporates the modelling of 3-D effects which result from secondary flow and mixing and lead to property changes in the streamwise and spanwise directions. The method requires no extra data for loss, deviation and blockage. The necessary input data are the geometry, upstream stagnation conditions, rotational speed and mass flow rate. Blade wakes and their decay are modelled. The secondary flow component of the mixing coefficient modifies the uniform part and the result is used in the turbulent diffusion terms of the equation of motion.

The P&W 3S1 low aspect ratio 3 stage compressor and UTRC 2 stage research compressor are used for validation. Considering the complexity of the flow in the multi-stage environment, it was concluded that the method gives encouraging results at a very economical rate.
Research and Development of Ceramic Turbine Wheels
Authors: Watanabe Keiichiro , Masuda Masaaki , Ozawa Tadao , Matsui Minoru , Matsuhird Keiji
Published: March 2015

The bending strength of specimens of various sizes, some of which were cut from a turbine wheel, was compared with predictions using Weibull statistical theory. The stress distribution of a ceramic turbine wheel in spin testing was determined with finite elements and the results were used to analyze a wheel that was spun until it burst. The cause of the burst of the ceramic radial turbine wheel at elevated temperature is discussed and based on the tensile rupture data, a design methodology using the Larson Miller parameter was found to be applicable to the ceramic components at elevated temperatures.
A Comparison of the Measured and Predicted Flowfield in a Modern Fan-Bypass Configuration
Authors: Goyal R. K. , Dawes W. N.
Published: March 2015

A 3-D viscous Navier-Stokes flow solver was used to predict core and bypass rotor performance and radial flow characteristics of a 4.6:1 bypass ratio, single stage fan. The 3-D flow solver can handle several blade rows simultaneously and has the capability to include a downstream splitter. Results of the analysis are compared with experimental data obtained during rig testing of a modern high bypass single stage turbofan in which rotor performance for both bypass and core streams was measured.
Investigation of Tip Clearance Phenomena in an Axial Compressor Cascade Using Euler and Navier-Stokes Procedures
Authors: Kunz R. F. , Lakshminarayana B. , Basson A. H.
Published: March 2015

Three-dimensional Euler and Full Navier-Stokes computational procedures have been utilized to simulate the flow field in an axial compressor cascade with tip clearance. An embedded H-grid topology was utilized to resolve the flow physics in the tip gap region. The numerical procedure employed is a finite difference Runge-Kutta scheme. Available measurements of blade static pressure distributions along the blade span, dynamic pressure and flow angle in the cascade outlet region, and spanwise distributions of blade normal force coefficient and circumferentially averaged flow angle are used for comparison. Several parameters which were varied in the experimental investigations were also varied in the computational studies. Specifically, measurements were taken and computations were performed on the configuration with and without: tip clearance, the presence of an endwall, inlet endwall total pressure profiles and simulated relative casing rotation. Additionally, both Euler and Navier-Stokes computations were performed to investigate the relative performance of these approaches in reconciling the physical phenomena considered. Results indicate that the Navier-Stokes procedure, which utilizes a low Reynolds number k-ε model, captures a variety of important physical phenomena associated with tip clearance flows with good accuracy. These include tip vortex strength and trajectory, blade loading near the tip, the interaction of the tip clearance flow with passage secondary flow and the effects of relative endwall motion. The Euler computation provides good but somewhat diminished accuracy in resolution of some of these clearance phenomena. It is concluded that the level of modelling embodied in the present approach is sufficient to extract much of the tip region flow field information useful to designers of turbomachinery.
Brush Seal Leakage Performance With Gaseous Working Fluids at Static and Low Rotor Speed Conditions
Authors: Carlile Julie A. , Hendricks Robert C. , Yoder Dennis A.
Published: March 2015

The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was investigated. This report includes the leakage results for air, helium, and carbon dioxide at several bristle/rotor interferences. In addition, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were investigated. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in.), a fence height of 0.0635 cm (0.025 in.), and 1800 bristles/cm-circumference (4500 bristles/in.-circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor.

The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times when compared to a non-lubricated brush seal. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.
Microstructural Investigations of Plasma Sprayed Yttria Partially Stabilized Zirconia TBC: in Relation to Thermomechanical Resistance and High Temperature Oxidation Mechanisms
Authors: Alperine S. , Lelait L.
Published: March 2015

This study deals with microstructural investigations of plasma sprayed yttria partially stabilized zirconia thermal barrier coatings, performed by classical and analytical transmission electron microscopy. The aim of the study was to determine eventual relationships between coating microstructure and toughness. The ceramic/metal interface which plays an important role during TBC thermomechanical sollicitation, has also been studied. In the 6 to 8 weight % Y2O3 range, the metastable tetragonal t’ phase is observed, showing special faulted microstructural features, such as grain twinning and antiphase boundary planes. Moreover, after high temperature annealing in air, a very fine and stable precipitation of the equilibrium cubic phase appears. It is believed that these microstructural elements could act as crack deviation sites and enhance coatings intrinsic toughness. Microstructural investigations of the alumina scales grown during high temperature annealing reveal yttrium segregation at oxide grain boundaries as well as significant quantities of zirconium inside the alumina grains. The oxide growth seems to be dominated by a classical grain boundary oxygen diffusion mechanism. The presence of zirconium inside the alumina grains suggests that Al2O3 also partially forms by chemical reduction of ZrO2 by Al.
Thermal Fracture of Multilayer Ceramic Thermal Barrier Coatings
Authors: Takeuchi Y. R. , Kokini K.
Published: March 2015

Controlled experiments and a corresponding analytical model were developed to investigate the reasons for crack initiation in multilayer ceramic thermal barrier coatings. The experiments and model determined that surface cracks form as a result of tensile stresses created following stress relaxation in the ceramic at steady state high temperatures (about 900°C-1100°C). Interface cracks generated by out of plane stresses are affected by the presence of these surface cracks and thermal transients and, possibly, edge effects.
Direct Measurements of Skin Friction in Supersonic Combustion Flow Fields
Authors: Chadwick K. M. , Deturris D. J. , Schetz J. A.
Published: March 2015

An experimental investigation was conducted to measure skin friction along the chamber walls of supersonic combustors. A direct force measurement device was used to simultaneously measure an axial and transverse component of the small tangential shear force passing over a non-intrusive floating element. This measurement was made possible with a sensitive piezoresistive deflection sensing unit. The floating head is mounted to a stiff cantilever beam arrangement with deflection due to the flow on the order of 0.00254 mm (0.0001 in). This allowed the instrument to be a non-nulling type. A second gauge was designed with active cooling of the floating sensor head to eliminate non-uniform temperature effects between the sensor head and the surrounding wall. The key to this device is the use of a quartz tube cantilever with piezoresistive strain gages bonded directly to its surface. A symmetric fluid flow was developed inside the quartz tube to provide cooling to the backside of the floating head. Tests showed that this flow did not influence the tangential force measurement. Measurements were made in three separate combustor test facilities. Tests at NASA Langley Research Center consisted of a Mach 3.0 vitiated air flow with hydrogen fuel injection at Pt = 500 psia (3446 kPa) and Tt = 3000 R (1667 K). Two separate sets of tests were conducted at the General Applied Science Laboratory (GASL) in a scramjet combustor model with hydrogen fuel injection in vitiated air at Mach = 3.3, Pt = 800 psia (5510 kPa), and Tt = 4000 R (2222 K). Skin friction coefficients between 0.001–0.005 were measured dependent on the facility and measurement location. Analysis of the measurement uncertainties indicate an accuracy to within ±10–15% of the streamwise component.
Effect of Manufacturing Deviations on Performance of Axial Flow Compressor Blading
Authors: Marson Ezio
Published: March 2015

Successful compressor aerodynamic performance can be achieved by satisfactory completion of requirements in the following three areas:

aerodynamic design

quality of blading

manufacturing and assembly of the components

Using presently available computer programs capable of doing detailed three dimensional analysis of the flow field, it is possible to obtain excellent aerodynamic designs exceeding 90% isentropic efficiency.

When the design requirements are deviated from the manufacturing process, the result will be less than optimum performance, for example: inadequate surge margin, lowered efficiency, reduced mass flow, etc. may be experienced.

Different types of manufacturing deviations and their effect on compressor performance are analysed in the paper by means of empirical formulas and considerations.
A New Approach to the Design of Combined Cycle Plants
Authors: Wiekmeijer Ir. Ted
Published: March 2015

The paper will deal with new developments on basis of the ideas, laid down in ASME paper 90-GT-180, presented at the Brussels Conference. In this former paper a combination of incinerators and cogen systems was described. New development show, that some of these ideas can also be used in cogen plants, in which all steam is raised and superheated in a waste heat boiler behind a high grade fuel fired gas turbine (natural gas or equivalent). This paper will deal give a description of the new system. A comparison will be made with conventional cogen systems, comprising of a gas turbine, a dual pressure non-fired waste heat boiler and a condensing steam turbine. On basis of a particular case study both the technical and financial performances will be compared with each other.
Optimization of an Advanced Combined Cycle and its Application to the Yokohama Thermal Power Station No. 7 and No. 8 Groups
Authors: Aizawa Zengo , Carberg William
Published: March 2015

Combined cycle technology was successfully applied to the 2000 MW Tokyo Electric Power Co. (TEPCO) Futtsu Station. The fourteen 165 MW single shaft combined cycle Stages were commissioned between 1985 and 1988. Since that time, experience has been accumulated on these 2000 deg F (1100 deg C) class gas turbine based Stages.

With the advent of 2300 deg F (1300 deg C) class gas turbines and dry low NOx technologies, an advanced combined cycle with substantially improved performance became possible. TEPCO commissioned General Electric, Toshiba and Hitachi to perform a study to optimize the use of these technologies. The study was completed and the participants are now doing detailed design of a plant consisting of eight 350 MW single shaft combined cycle Stages. The plant will be designated the Yokohama Thermal Power Station No. 7 and No. 8 Groups.

This paper discusses experience gained at the Futtsu Station, the results of the optimization study for an advanced combined cycle and the progress of the design for Yokohama Groups No. 7 and No. 8.
Separated Flow in a Low Speed Two-Dimensional Cascade: Part II — Cascade Performance
Authors: Yocum Adam M. , O’Brien Walter F.
Published: March 2015

This study was conducted for the purpose of providing a more fundamental understanding of separated flow in cascades and to provide performance data for fully-stalled blade rows. Cascades of a single blade geometry and a solidity of unity were studied for three stagger angles and the full range of angle of attack extending well into the stalled flow regime. The Reynolds number was also varied for a limited number of cases. Results from velocity and pressure measurements made in the cascade and the overall cascade performance evaluated from these measurements are presented. In addition, results from a numerical simulation of the flow through a cascade of flat plate airfoils are used to further illustrate the effects of blade stagger and to define the correct limits for the cascade performance. The results indicate that the slope of the total pressure loss versus angle of attack curve for the flow immediately downstream of the cascade is steeper for cascades with greater stagger. The normal force coefficient was found to increase to a peak value near the angle of attack where full leading edge stall first occurs. A further increase in angle of attack results in a decline in the normal force coefficient. The peak value of the normal force coefficient is greater and occurs at a higher angle of attack for the cascades with smaller stagger.
Thrust Vectoring/Reversing Tactics in Air-to-Air Combat
Authors: Boppe C. W. , Martorella R. P.
Published: March 2015

Considerable effort is now underway to develop technologies for enhancing fighter maneuvering limits. This has in part been motivated by the capabilities of advanced air-to-air missiles. One approach to enhanced combat effectiveness involves flight envelope expansion and improved controllability via engine thrust-vectoring and thrust-reversing. The complexity of fighter combat, however, makes it difficult to perform engineering analyses for assessing potential technological enhancements and risks. This paper describes a digital simulation that has been used to identify benefits associated with improved maneuverability. The Navy/Grumman F-14 aircraft provides the flight characteristics database. Combat tactics are developed as part of the solution process and are based solely on characteristics of the combatants and weapons employed. Head-on and co-directional neutral start combat engagements are used to illustrate study results.
Effective Sealing of a Disk Cavity Using a Double-Toothed Rim Seal
Authors: Bhavnani S. H. , Khilnani V. I. , Tsai L.-C. , Khodadadi J. M. , Goodling J. S. , Waggott J.
Published: March 2015

The trend towards higher gas turbine inlet temperatures is a natural consequence of the pursuit of higher turbine operating efficiencies. More efficient disk cooling technology is therefore a prime need. The sealing characteristics of a advanced air-cooled turbo-expander disk cavity have been studied using laser sheet flow visualization and static pressure measurements. Experiments were performed on a simplified half-scale model of an actual low pressure turbo-expander first-stage disk cavity. The rotor-stator geometry tested was equipped with a double-toothed rim (DTR) seal at the outer periphery and a labyrinth seal (or shaft seal) at the inner periphery of the cavity. This is one of the first studies that incorporates the effects of shaft sealing flows. Experiments were conducted in the absence of an external flow stream for various labyrinth seal flow rates, and rotational Reynolds numbers up to 1.52 × 106. The results confirm the adequacy of previously estimated design data for this disk cavity configuration. Pressure measurements reveal that a pressure difference criterion based on the differential pressure across the teeth of the rim seal can be used to detect ingress of mainstream flow. The superior performance of the seal geometry studied was confirmed by a comparison against a single-toothed rim seal and a simple axial rim seal.
Selection, Development, and Application of Forming and Densification Techniques for Silicon Nitride Heat Engine Components
Authors: Pollinger J. , Busovne B. , Meiser M. , Nick J.
Published: March 2015

A wide variety of silicon nitride structural ceramic components are currently being developed and evaluated for advanced heat engine applications. The size, geometry, and performance requirements of these components are the criteria driving the selection of the appropriate forming process and densification process. The different forming and densification processes have unique forming and resulting property advantages and limitations which must be considered during the selection process. Specific heat engine component applications, including gas turbine components such as hot section wheels and stators, and internal combustion engine cam rollers will be discussed and the rationale for selection of the material, forming process, and densification process will be presented. Performance of the components will be related to the material, forming, and densification techniques used. The forming techniques discussed are slip casting, injection molding, and compaction/ isostatic pressing. The densification techniques discussed are sintering, sinter-HIP, and glass-encapsulation-HIP.
Development and Application of a Low Cost Integrated Based System for the Operation and Condition Based Maintenance of Gas Turbines
Authors: Higgins H. C. , Hackett J. L.
Published: March 2015

British Gas is the largest integrated gas company in the western world operating on both sides of the Atlantic. Within the UK, the companies activities embrace off-shore exploration and production, transmission and distribution together with the retailing and installation of appliances in customers homes.
LV100 AIPS Technology—For Future Army Propulsion
Authors: Brockett Walter , Koschier Angelo
Published: March 2015

The overall design of and Advanced Integrated Propulsion System (AIPS), powered by an LV100 gas turbine engine, is presented along with major test accomplishments. AIPS was a demonstrator program that included design, fabrication, and test of an advanced rear drive powerpack for application in a future heavy armored vehicle (54.4 tonnes gross weight). The AIPS design achieved significant improvements in volume, performance, fuel consumption, reliability/durability, weight and signature reduction. Major components of AIPS included the recuperated LV100 turbine engine, a hydrokinetic transmission, final drives, self-cleaning air filtration (SCAF), cooling system, signature reduction systems, electrical and hydraulic components, and control systems with diagnostics/prognostics and maintainability features.
Low CO2 Power Generation Options and Their Environmental Impact
Authors: Bower C. J. , Goldthorpe S. H. , Fynes G.
Published: March 2015

The Global Warming R&D Programme at the Coal Research Establishment is evaluating options for removing CO2 from coal-fired power plant. The aim is to identify coal-based technologies with minimal emissions of CO2 as contingency planning in case the most pessimistic fears of warming are realised. Two promising options based on Integrated Gasification Combined Cycle have been identified, so far. One incorporates a conventional CO shift conversion step and a physical solvent scrubbing process to remove 90% of the CO2 and 99% of the H2S. The second approach is conceptual, using CO shift but also a membrane gas separator. The gas turbine would be fired with hydrogen in both cases. A discussion of the environmental impact of these schemes suggests that they would be very much cleaner than current technology using Pulverised Fuel combustion with Flue Gas Desulphurisation. CO2 disposal options and needs for future work are also discussed.
High Pressure Ratio Intercooled Turboprop Study
Authors: Rodgers C.
Published: March 2015

High altitude long endurance unmanned aircraft impose unique contraints on candidate engine propulsion systems and types. Piston, rotary and gas turbine engines have been proposed for such special applications. Of prime importance is the requirement for maximum thermal efficiency (minimum specific fuel consumption) with minimum waste heat rejection. Engine weight, although secondary to fuel economy, must be evaluated when comparing various engine candidates. Weight can be minimized by either high degrees of turbocharging with the piston and rotary engines, or by the high power density capabilities of the gas turbine.

The design characteristics and features of a conceptual high pressure ratio intercooled turboprop are discussed. The intended application would be for long endurance aircraft flying at an altitude of 60,000 ft. (18,300 m). It is estimated that such a turboprop would be capable of thermal efficiencies exceeding 40% with current state-of-the-art component efficiency levels and an overall compressor pressure ratio of 66.0. Projected Power (at altitude) to weight ratio is comparable to that of competitive piston and rotary engines.