bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Coriolis Force on Instability of Laminar Boundary Layer on a Concave Surface
Authors: Kikuyama Koji , Hasegawa Yutaka , Yokoi Takashi , Hirota Masashi
Published: February 2015

Stability of laminar boundary layer having a mean velocity of Pohlhausen type was studied by solving numerically the perturbation equations when the boundary layer is subject to curvature and Coriolis force. When the channel rotates so that the Coriolis force acts toward the concave wall, the Taylor-Görtler vortices are generated on a concave surface with a weaker curvature than that in the stationary condition because of the instability effects of the Coriolis force. Vortices are suppressed and the critical Görtler number is increased when the Coriolis force acts opposite to the centrifugal force due to the wall curvature. Over a wide range of rotation rate, vortices with scales as large as the boundary layer thickness are easily generated.
Enhanced Heat Transfer and Shear Stress due to High Freestream Turbulence
Authors: Thole K. A. , Bogard D. G.
Published: February 2015

Surface heat transfer and skin friction enhancements, as a result of freestream turbulence levels between 10% < Tu < 20%, have been measured and compared in terms of correlations given throughout the literature. The results indicate that for this range of turbulence levels, the skin friction and heat transfer enhancements scale best using parameters which are a function of turbulence level and dissipation length scale. However, as turbulence levels approach Tu = 20%, the St′ parameter becomes more applicable and simpler to apply. As indicated by the measured rms velocity profiles, the maximum streamwise rms value in the near-wall region, which is needed for St′, is the same as that measured in the freestream at Tu = 20%. Analogous to St′, a new parameter, Cf, was found to scale the skin friction data. Independent of all the correlations evaluated, the available data show that the heat transfer enhancement is greater than enhancements of skin friction with increasing turbulence levels. At turbulence levels above Tu = 10%, the freestream turbulence starts to penetrate the boundary layer and inactive motions begin replacing shear-stress producing motions that are associated with the fluid/wall interaction. Although inactive motions do not contribute to the shear stress, these motions are still active in removing heat.
Evolution and Experience of the Mars 100LS Gas Turbine
Authors: Jones Malcolm D. , Pytanowski Greg P. , Files Doyle L. , Wilson Jay M.
Published: February 2015

Solar’s Mares 100LS industrial gas turbine rated at 11.2 MW (15,000 hp) and 34% thermal efficiency at ISO conditions is the latest model Mars gas turbine evolved from an ongoing program of planned continuous product improvement. Since the Mars gas turbine was introduced in 1978, over 250 units have been ordered and approximately 4 million hours of field experience have been logged with packages designed for gas compression, pump drive, and electrical power generation. This paper updates the description of the Mars gas turbine to include the three latest enhancements: redesign of the first two compressor stages for increased output power and efficiency; SoLoNOx (dry low NOx, antipollution) combustion system: and a new low speed power turbine to improve output drive versatility.
Thermodynamical Optimization of a Combined Cycle Plant Performance
Authors: Sarabchi K. , Polley G. T.
Published: February 2015

Computer modelling of Performance optimization was done to examine the effect of key operating variables like compressor pressure ratio, turbine inlet temperature, and recovery boiler pressure on performance parameters of a simple combined cycle and comparison was made to a simple gas turbine cycle. Both thermal efficiency and specific net work were examined as pressure ratio and recovery boiler pressure were varied for each turbine inlet temperature. Also careful consideration was given to admissible values of stack gas temperature, steam turbine outlet dryness fraction, and steam turbine outlet dryness fraction, and steam turbine inlet temperature.

Specifically, it was shown that when we treat a combined cycle as an integrated system, efficiency optimization entails a pressure ratio below that suitable for simple gas turbine plant.
Thermal Energy Storage and Inlet Air Cooling for Combined Cycle
Authors: Ebeling Jerry , Balsbaugh Robert , Blanchard Steven , Beaty Lawrence
Published: February 2015

The paper will discuss the application of Thermal Energy Storage (TES) using ice and inlet air cooling at the Fayetteville (North Carolina, USA) Public Works Commission (PWC) Butler-Warner Generation Plant. The Butler-Warner Generating Plant consists of eight General Electric Frame 5 combustion turbines and a single steam turbine. Six of the combustion turbines exhaust through three Heat Recovery Steam Generators (HRSG). The project consisted of modifying the inlets of all eight combustion turbines to accommodate plate fin cooling coils and new air filters; and the design and construction of the TES ice production and storage facilities. A feasibility study was completed in June 1992. Detail designed began in August 1992. Initial operation was June 1993. The modifications have been completed and the plant has experienced a 29% capacity increase as a result of the project.
Film Cooling With Compound Angle Holes: Heat Transfer
Authors: Sen Basav , Schmidt Donald L. , Bogard David G.
Published: February 2015

Heat transfer coefficients have been measured for film cooling injection from a single row of holes laterally directed with a compound angle of 60°. Two hole configurations were tested, round holes and holes with a diffusing expansion at the exit. Streamwise directed round holes were also tested as a basis for comparison. All the holes were inclined at 35° with respect to the surface. The density ratio was 1.0, momentum flux ratios ranged from I = 0.16 to 3.9 and mass flux ratios from M = 0.4 to 2.0. Results are presented in terms of hf/h0, the ratio of film cooling heat transfer coefficient to the heat transfer coefficient for the undisturbed turbulent boundary layer at the same location. Results indicate that for the streamwise directed holes, the heat transfer rates are close to the levels that exist without injection. Similarly, at low momentum flux ratio, holes with a large compound angle had little effect on heat transfer rates. But at high momentum flux ratios, holes with a large compound angle had significantly increased heat transfer levels. The results were combined with adiabatic effectiveness results to evaluate the overall performance of the three geometries. It is shown that for evaluation of film cooling performance with compound angle injection, especially at high momentum flux ratios, it is critical to know the heat transfer coefficient, as the adiabatic effectiveness alone does not determine the performance. Compound angle injection at high momentum flux ratios gives higher effectiveness values than streamwise directed holes, but the higher heat transfer levels result in poorer overall performance.
A Quasi-3D Calculation Method for Gas Turbine Combustor Liner Wall Cooling Techniques
Authors: Rizk N. K.
Published: February 2015

To obtain more accurate estimates of wall temperature of gas turbine combustors, it is essential to include the radiation flux contribution from the flame and hot gases into each wall segment. This step calls for the knowledge of the detailed three-dimensional combustor flow field in addition to an accurate means of defining a radiation view factor. In the present investigation, a quasi-three-dimensional calculation method is adopted to predict the wall temperature of a number of production combustors. The method utilizes the flow field parameters as given by the analytical code to evaluate the radiation and convection heat loading to the wall. It makes use of empirical expressions for overall effectiveness of different cooling schemes including conventional film cooling, extended surface convective/film cooling, impingement jets and transpiration systems such as Lamilloy*, effusion, and compliant matrix cooling. The calculation technique takes into account the fuel effects on wall temperature through their impact on the detailed flow field and radiation flux. The model validation involved comparing the calculations with the measured data of several combustors that used either film cooling devices or effusion hole schemes and operated on typical aviation fuels as well as special high density fuel types. An investigation of such effects as air distribution and the spray SMD on wall temperature was also conducted in the present effort.
Effects of Periodic Unsteady Wake Flow and Pressure Gradient on Boundary Layer Transition Along the Concave Surface of a Curved Plate
Authors: Schobeiri M. T. , Radke R. E.
Published: February 2015

Boundary layer transition and development on a turbomachinery blade is subjected to highly periodic unsteady turbulent flow, pressure gradient in longitudinal as well as lateral direction, and surface curvature. To study the effects of periodic unsteady wakes on the concave surface of a turbine blade, a curved plate was utilized. On the concave surface of this plate, detailed experimental investigations were carried out under zero and negative pressure gradient. The measurements were performed on an unsteady flow research facility using a rotating cascade of rods positioned upstream of the curved plate. Boundary layer measurements using a hot-wire probe were analyzed by the ensemble-averaging technique. The results presented in the temporal-spatial domain display the transition and further development of the boundary layer, specifically the ensemble-averaged velocity and turbulence intensity. As the results show, the turbulent patches generated by the wakes have different leading and trailing edge velocities and merge with the boundary layer resulting in a strong deformation and generation of a high turbulence intensity core. After the turbulent patch has totally penetrated into the boundary layer, pronounced becalmed regions were formed behind the turbulent patch and were extended far beyond the point they would occur in the corresponding undisturbed steady boundary layer.
Development of Silicon Nitride Rotors for Gas Turbine Applications
Authors: Yoshida Makoto , Tsuruzono Sazo , Ono Takashi , Gejima Hiroshi
Published: February 2015

Kyocera is developing various ceramic parts for gas turbines under the government funded ceramic gas turbine development programs in Japan. Among the programs, Kyocera is contracted for the development components for CGT-302 and CGT-303 engines which are designed for 300kW output power generation. Of the various parts for gas turbines, we discuss developments and burst tests at room temperature of silicon nitride turbine rotors made by slip casting.

In particular, the result of burst tests of turbine rotors at room temperature is evaluated along with the strength prediction by a computer program (CARES) developed by NASA. Different types of turbine rotors were tested, and their burst speeds were well correlated to the strength predicted by computer analyses. This suggests that fracture stress of ceramic parts is well predicted from the material data.
Integration of Combustion Turbine Systems Into Pressurized Fluidized Bed Combustion Combined Cycles
Authors: Newby R. A. , Domeracki W. F. , McGuigan A. W. , Bannister R. L.
Published: February 2015

Currently, pressurized fluidized bed combustion (PFBC) combined cycle power plants apply multiple stages of cyclones to clean the combustion products prior to turbine expansion, and rugged, inefficient expanders are required for this dirty-gas duty. The turbine inlet temperature is limited to the fluid bed combustor temperature, about 843°C (1550°F), so the plant thermal efficiency is relatively low. The development of hot gas filtration and coal-gas topping for PFBC combined cycles is the next step in the evolution of PFBC, and will result in the use of modern, high-efficiency combustion turbines in PFBC applications as well as plant thermal efficiencies up to 47% (HHV). Westinghouse is developing integrated combustion turbine systems that interface with PFBC plants and incorporate the functions of hot gas filtration, alkali vapor removal, topping combustion, hot gas piping and control, and turbine compression and expansion. This paper reports on the engineering considerations made by Westinghouse for these integrated combustion turbine systems and summarizes the current development activities and status.
Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower
Authors: Ohta Yutaka , Outa Elsuke , Tajima Klyohiro
Published: February 2015

The blade-passing frequency noise, abbreviated to BPF noise, of low specific speed centrifugal blower is analyzed by separating the frequency-response of the transmission passage and the intensity of the noise source. Frequency-response has previously been evaluated by the authors using a one-dimensional linear wave model, and the results have agreed well with the experimental response in a practical range of the blower speed. In the present study, the intensity of the noise source is estimated by introducing the quasi-steady model of the blade wake impingement on the scroll surface. The effective location of the noise source is determined by analyzing the cross-correlation between measured data of the blower suction noise and pressure fluctuation on the scroll surface. Then, the surface density distribution of a dipole noise source is determined from pressure fluctuation expressed in terms of quasi-steady dynamic pressure of the traveling blade wake. Finally, the free-field noise level is predicted by integrating the density spectrum of the noise source over the effective source area. The sound pressure level of the blower suction noise is easily predicted by multiplying the free-field noise level by the frequency-response characteristics of the noise transmission passage.
Improved Blade Profile Loss and Deviation Angle Models for Advanced Transonic Compressor Bladings: Part II — A Model for Supersonic Flow
Authors: König W. M. , Hennecke D. K. , Fottner L.
Published: February 2015

New blading concepts as used in modern transonic axial-flow compressors require improved loss and deviation angle correlations. The new model presented in this paper incorporates several elements and treats separately blade-row flows having subsonic and supersonic inlet conditions. The second part of the present report focuses on the extension of a well-known correlation for cascade losses at supersonic inlet-flows. It was originally established for DCA-bladings and is now modified to reflect the flow situation in blade-rows having low-cambered, arbitrarily designed blades including precompression blades. Finally, the steady loss increase from subsonic to supersonic inlet-flow velocities demonstrates the matched performance of the different correlations of the new model.
Local Heat Transfer in a Rotating Two-Pass Triangular Duct With Smooth Walls
Authors: Dutta Sandip , Han Je-Chin , Zhang Yuming , Lee C. Pang
Published: February 2015

Earlier heat transfer studies with orthogonal rotation were conducted mostly on ducts of square cross-section. This paper reports a different cross-section, a triangular duct. Unlike a square cross-section, the triangular shape provides more restriction to the formation of the secondary flows. Moreover, the studied orientation of the right triangular duct avoids formation of symmetric vortex structures in the cross flow plane. This paper presents turbulent heat transfer characteristics of a two-pass smooth walled triangular duct. One pass is for radial outward flow and the other for radial inward flow. With rotation the radial outward and inward flow directions show different surface heat transfer characteristics. Like a square duct, differences between the trailing and the leading Nusselt number ratios for the triangular duct increase with rotation number. However, the rate of change of Nusselt number ratios with rotation number varies for the two duct geometries. Standard k-ε model predictions for a radial outward flow situation show that the Nusselt number ratio variations with Reynolds number are not drastic for the same rotation number.
Nonlinear Behavior of a Magnetic Bearing System
Authors: Virgin Lawrence N. , Walsh Thomas F. , Knight Josiah D.
Published: February 2015

This paper describes the results of a study into the dynamic behavior of a magnetic bearing system. The research focuses attention on the influence of nonlinearities on the forced response of a two-degree-of-freedom rotating mass suspended by magnetic bearings and subject to rotating unbalance and feedback control. Geometric coupling between the degrees of freedom leads to a pair of nonlinear ordinary differential equations which are then solved using both numerical simulation and approximate analytical techniques. The system exhibits a variety of interesting and somewhat unexpected phenomena including various amplitude driven bifurcational events, sensitivity to initial conditions and the complete loss of stability associated with the escape from the potential well in which the system can be thought to be oscillating. An approximate criterion to avoid this last possibility is developed based on concepts of limiting the response of the system. The present paper may be considered as an extension to an earlier study by the same authors which described the practical context of the work, free vibration, control aspects and derivation of the mathematical model.
Infrared Thermal Imaging System as a Diagnostic Tool for Gas Turbine Engine Faults
Authors: MacLeod J. D. , Steckhan P. , He D.
Published: February 2015

With the cost of maintaining a fleet of gas turbine engines continuing to rise, there is a greater need to develop methods to diagnose engine deterioration and identify faulty engine components quickly and efficiently. The Structures, Materials and Propulsion Laboratory of the National Research Council of Canada (NRC) has established a program to develop and evaluate various diagnostic techniques. The effort is aimed at investigating the effects of typical in-service faults on engine performance characteristics. An important aspect of the engine test program is the evaluation of non-intrusive sensors to accurately measure gas turbine performance.

Using infrared thermography, the measurement of temperature is accomplished non-intrusively using the infrared radiation spectra. This instrumentation provides an indirect measurement of temperature and does not interfere with the flow field being measured. The temperature patterns can be used to determine engine health, and identify possible fault conditions within the hot section of the engine.

This paper describes the project objectives, the experimental installation, and the results of the performance evaluations. A description of the infrared thermography system, and the data reduction and analysis systems used to convert infrared light into temperature profile contours is given.
Biomass Externally Fired Gas Turbine Cogeneration
Authors: Eidensten Lars , Yan Jinyue , Svedberg Gunnar
Published: February 2015

This paper is a presentation of systematic study on externally fired gas turbine cogeneration fueled by biomass. The gas turbine is coupled in series with a biomass combustion furnace in which the gas turbine exhaust is used to support combustion. Three cogeneration systems have been simulated. They are systems without a gas turbine, with a non top-fired gas turbine, and a top-fired gas turbine. For all systems, three types of combustion equipment have been selected: circulating fluidized bed (CFB) boiler, grate fired steam boiler and grate fired hot water boiler. The sizes of biomass furnaces have been chosen 20 MW and 100 MW fuel inputs. The total efficiencies based on electricity plus process heat, electrical efficiencies, and the power-to-heat ratios for various alternatives have been calculated. For each of the cogeneration systems, part load performance with varying biomass fuel input is presented. Systems with CFB boilers have a higher total efficiency and electrical efficiency than other systems when a top-fired gas turbine is added. However, the systems with grate fired steam boilers allow higher combustion temperature in the furnace than CFB boilers do. Therefore, a top combustor may not be needed when high temperature is already available. Only one low grade fuel system is then needed and the gas turbine can operate with very clean working medium.
Wake Region Measurements of a Highly Three-Dimensional Nozzle Guide Vane Tested at DRA Pyestock Using Particle Image Velocimetry
Authors: Funes-Gallanzi M. , Bryanston-Cross P. J. , Chana K. S.
Published: February 2015

The quantitative whole field flow visualization technique of PIV has over the last few years been successfully demonstrated for transonic flow applications. A series of such measurements has been made at DRA Pyestock. Several of the development stages critical to a full engine application of the work have now been achieved using the Isentropic Light Piston Cascade (ILPC) test facility operating with high inlet turbulence levels:

• A method of seeding the flow with 0.5μm diameter styrene particles has provided an even coverage of the flow field.

• A method of projecting a 1 mm thick high power Nd/YAG laser light sheet within the turbine stator cascade. This has enabled a complete instantaneous intra-blade velocity mapping of the flow field to be visualized, by a specially developed diffraction-limited optics arrangement.

• Software has been developed to automatically analyze the data. Due to the sparse nature of the data obtained, a spatial approach to the extraction of the velocity vector data was employed.

• Finally, a comparison of the experimental results with those obtained from a three-dimensional viscous flow program of Dawes; using the Baldwin-Lomax model for eddy viscosity and assuming fully turbulent flow.

The measurements provide an instantaneous quantitative whole field visualization of a high-speed unsteady region of flow in a highly three-dimensional nozzle guide vane; which has been successfully compared with a full viscous calculation. This work represents the first such measurements to be made in a full-size transonic annular cascade at engine representative conditions.
A Study on the Dynamic Characteristics of Geared Rotor-Bearing System With Hybrid Method
Authors: Shiau T. N. , Chou Y. W. , Chang J. R. , Nelson H. D.
Published: February 2015

The dynamic behavior of a geared rotor bearing systems with coupled torsional-lateral motion is investigated using a Hybrid Method which combines the merits of the Finite Element Method and the Generalized Polynomial Expansion Method. The effects of the stiffness and damping of the bearings and the gear mesh, the mesh angle and the location of the gear mesh are also studied. Natural whirl speed analyses and steady state responses due to mass unbalance and transmission error excitation are presented. The accuracy and the efficiency of the method are demonstrated. The results show that the torsional-lateral coupled modes of the system are strongly affected by the stiffness, damping, and mesh angle of the gear mesh. The steady state response amplitudes due to transmission error at tooth passing frequency are high. The application of hybrid method to the geared rotor-bearing system leads to improved computational efficiency compared to the finite element method without lose of accuracy.
System Evaluation and LBTU Fuel Combustion Studies for IGCC Power Generation
Authors: Cook C. S. , Corman J. C. , Todd D. M.
Published: February 2015

The integration of gas turbines and combined cycle systems with advances in coal gasification and gas stream cleanup systems will result in economically viable IGCC systems. Optimization of IGCC systems for both emission levels and cost of electricity is critical to achieving this goal.

A technical issue is the ability to use a wide range of coal and petroleum-based fuel gases in conventional gas turbine combustor hardware. In order to characterize the acceptability of these syngases for gas turbines, combustion studies were conducted with simulated coal gases using full scale advanced gas turbine (7F) combustor components. It was found that NOx emissions could be correlated as a simple function of stoichiometric flame temperature for a wide range of heating values while CO emissions were shown to depend primarily on the H2 content of the fuel below heating values of 130 Btu/scf (5125 kJ/NM3) and for H2/CO ratios less than unity. The test program further demonstrated the capability of advanced can-annular combustion systems to burn fuels from air-blown gasifiers with fuel lower heating values as low as 90 Btu/scf (3548 kJ/NM3) at 2300 F (1260 C) firing temperature.

In support of ongoing economic studies, numerous IGCC system evaluations have been conducted incorporating a majority of the commercial or near commercial coal gasification systems coupled with “F” series gas turbine combined cycles. Both oxygen and air-blown configurations have been studied, in some cases with high and low temperature gas cleaning systems. It has been shown that system studies must start with the characteristics and limitations of the gas turbine if output and operating economics are to be optimized throughout the range of ambient operating temperature and load variation.
Design Method for Turbomachine Blades With Finite Thickness by the Circulation Method
Authors: Jiang Jun , Dang Thong
Published: February 2015

This paper presents a procedure to extend a well-developed fully three-dimensional inverse method for infinitely-thin blades to handle blades with finite thickness. In this inverse method, the prescribed quantities are the blade pressure loading and the blade thickness distributions, and the calculated quantity is the blade geometry. The method is formulated in the fully inverse mode whereby the blade shape is determined iteratively using the flow-tangency condition along the blade surfaces. This technique is demonstrated here in the first instance for the design of cascaded blades in inviscid and incompressible flows. Design calculations are presented for an inlet guide vane, an impulse turbine blade, and a compressor blade. Consistency checks are carried out for these design calculations using a panel analysis method and the analytical solution for the Gostelow profile.
Composite Filter System Development and Performance
Authors: Belcher M.
Published: February 2015

Gas turbine operation in urban environments creates new challenges in inlet filtration. The particulate concentration could be light, but significant quantities of the particles are sub-micron in size. Additionally, the presence of hydrocarbons can cause problems with air filter performance, both through short life and turbine fouling.

A new filter system for these environments is described. Development objectives for the medias and filter systems are discussed, test and evaluation procedures are defined, and the performance of the resulting product is documented.
Experimental Evaluation of the Damping Factor of Various Rotor-Bearing Configurations
Authors: ul Haq Inam
Published: February 2015

Rotor-bearing system dynamics can only be clearly understood if the magnitude of the structure internal properties (damping, stiffness) are known. Seldom are these properties known to users and researchers. Particularly, industrial users of machines are concerned with the in-situ structural (structure of machine and foundation) properties which provide better insight for understanding the machinery characteristics behaviors. In this paper, a simple method is outlined for calculating the damping factor with the help of Polar and Bodé plots. Pertinent equations are also developed. Experimental results shows the rotors supported by journal bearings (air and oil lubricated) have the damping factor in the range of 0.0349 ∼ 0.0386.
Development of Two-Dimensional Turbulent Wakes in a Curved Channel at Positive Streamwise Pressure Gradient
Authors: John J. , Schobeiri M. T.
Published: February 2015

The development of turbomachinery wake flows are greatly influenced by streamline curvature and streamwise pressure gradient. This paper is a part of a comprehensive experimental and theoretical study on the development of the steady and the periodic unsteady turbulent wakes in curved channels at different streamwise pressure gradients. The experimental investigation of the two-dimensional wake behind a stationary circular cylinder in a curved channel at positive streamwise pressure gradient is reported in this paper. Measurements of mean velocity and Reynolds stress components are carried out using a X-hot-film probe. The measured quantities obtained in probe coordinates are transformed to a curvilinear coordinate system along the wake center line and are presented in similarity coordinates. The results indicates strong asymmetry in velocity and Reynolds stress components. The Reynolds stress components have higher values at the inner half of the wake than at the outer half of the wake. However, the mean velocity defect profiles in similarity coordinates is almost symmetric and follows the same Gaussian function for the straight wake data. A comparison with the wake development in a curved channel at zero streamwise pressure gradient suggests that the decay rate of velocity defect is slower and the growth of wake width is faster in the case of positive streamwise pressure gradient.
Observations of Flame Behavior From a Practical Fuel Injector Using Gaseous Fuel in a Technology Combustor
Authors: Hedman Paul O. , Sturgess Geoffrey J. , Warren David L. , Goss Larry P. , Shouse Dale T.
Published: February 2015

This paper presents results from an Air Force program being conducted by researchers at Brigham Young University (BYU) Wright-Patterson Air Force Base (WPAFB), and Pratt and Whitney Aircraft Co (P&W). This study is part of a comprehensive effort being supported by the Aero Propulsion and Power Laboratory at Wright-Patterson Air Force Base, and Pratt and Whitney Aircraft, Inc. in which simple and complex diffusion flames are being studied to better understand the fundamentals of gas turbine combustion near lean blowout. The program’s long term goal is to improve the design methodology of gas turbine combustors.

This paper focuses on four areas of investigation: 1) digitized images from still film photographs to document the observed flame structures as fuel equivalence ratio was varied, 2) sets of LDA data to quantify the velocity flow fields existing in the burner, 3) CARS measurements of gas temperature to determine the temperature field in the combustion zone, and to evaluate the magnitude of peak temperature, and 4) two-dimensional images of OH radical concentrations using PLIF to document the instantaneous location of the flame reaction zones.
Future Vehicular Recuperator Technology Projections
Authors: Wilson Robert A. , Kupratis Daniel B. , Kodali Satyanarayana
Published: February 2015

The Department of Defense and NASA have funded a major gas turbine development program, Integrated High Performance Turbine Engine Technology (IHPTET), to double the power density and fuel economy of gas turbines by the turn of the century. Seven major US gas turbine developers participated in this program. While the focus of IHPTET activity has been aircraft propulsion, the same underlying technology can be applied to water craft and terrestrial vehicle propulsion applications, such as the future main battle tank. For these applications, the gas turbines must be equipped with recuperators. Currently, there is no technology roadmap or set of goals to guide industry and government in the development of a next generation recuperator for such applications.
Thermal and Loading Effects on Mechanical Properties of a Hot Isostatically Pressed Si3N4
Authors: Sankar Jagannathan , Neogi Jayant , Neogi Suneeta S. , Dixie Marvln T. , Vaidyanathan Ranji
Published: February 2015

The effect of thermal soaking on the mechanical properties of a candidate material for advanced heat engine applications namely, hot isostatically pressed (HIPed) silicon nitride (GTEPY6) are reported here. Pure uniaxial tensile tests conducted at room and at elevated temperatures indicated that the tensile strength of this material dropped significantly after 1000°C. The residual tensile strength of PY6 material after thermal soaking at 1200° and 1300°C was also investigated. Test results showed that thermal soaking at 1200° and 1300°C increased the residual tensile strength. The thermal soaking time had a greater effect on the residual tensile strength at 1300°C. Tensile creep tests performed at 1200° and 1300°C showed that the steady state creep rate was influenced by both the temperature and the applied stress. The higher stress exponent in HIPed as compared to a sintered silicon nitride shows higher creep resistance in the case of HIPed materials.
Imbalance Effects in Rotor Systems Under High Angular Accelerations
Authors: Neilson R. D. , Barr A. D. S. , Blandford-Baker N. J.
Published: February 2015

To assess correctly the effects of transient vibration in a system with imbalance care is required in modelling the system. This is particularly true in cases of extreme imbalance e.g. a blade-off simulation in turbo-machinery. Generally, however, the imbalance is modelled as a simple mrΩ2 term applied when the blade is released but this does not include all possible terms. This paper presents the detailed equations of motion of a flexible rotor system with distributed imbalance. The equations are presented in a rotating coordinate system. The modelling includes coupling between the torsional, lateral and axial motions. A simpler model of a two disk system is then presented in fixed coordinates. The disks which can move laterally am connected by a massless shaft which has both lateral and torsional stiffness giving the system six degrees of freedom. An analysis is presented showing that the model is the same as the conventional model for steady state circular orbits. Results from a simplified blade-off simulation are then presented and compared to the standard mrΩ2 model. The conclusion drawn from these simulations is that the additional terms should be included for high angular acceleration transient problems.
An Uncertainty Analysis of Inlet Dynamic Distortion Data Using an Analog/Digital Hybrid Editing System
Authors: Zelenak Maryann
Published: February 2015

The objectives of this analysis were to establish precision and bias errors for an analog-digital hybrid computer system (DYNADEC) used in the dynamic data editing phase of inlet wind tunnel testing. An uncertainty analysis was initiated to evaluate the system using inlet data from the Aeronautical Systems Center (ASC)/Arnold Engineering Development Center (AEDC) Aeropropulsion System Test Facility (ASTF) Freejet Development Program. Three test points from a subscale freejet test of the F-15 air induction system and three test points from a wind tunnel test of this same F-15 inlet model were selected to represent a wide range of test conditions and turbulence levels. Precision errors of the 40 total pressure probes at the location of the engine face were 1–2% of the 40 total pressure recovery magnitudes. Precision errors of the Pratt and Whitney Ka2 distortion index, the parameter used to edit the data on DYNADEC, were also investigated. These results indicated that Ka2 precision errors decreased with higher turbulence levels. Static bias errors were also computed by sending known signals through the DYNADEC system and measuring the output quantity. Static bias errors were much smaller in comparison to the precision error magnitudes and were considered negligible. This analysis also provided a foundation to evaluate future data sets using this editing system.
The Flight Testing of Natural and Hybrid Laminar Flow Nacelles
Authors: Barry Brian , Parke Simon J. , Bown Nicholas W. , Riedel Hansgeorg , Sitzmann Martin
Published: February 2015

The achievement of large areas of laminar flow over aircraft engine nacelles offers significant savings in aircraft fuel consumption. Based upon current engine configurations nett sfc benefits of up to 2% are possible. In addition the engine nacelle is ideally suited to the early inclusion of laminar flow technology, being relatively self contained with the possibility of application to existing airframes.

In September 1992 a European Consortium managed by Rolls-Royce including MTU and DLR began flight testing of a natural laminar flow nacelle. This programme was later extended by R-R and DLR to flight test a hybrid laminar flow nacelle featuring boundary layer suction and insect contamination protection.

The tests evaluated the effects of flight and engine environment, boundary layer transition phenomena, suction system operation and insect contamination avoidance strategies.

This paper describes the global conclusions from these flight tests which are a significant milestone leading to the future application of laminar flow technology to engine nacelles.
Advanced Turbine Systems Program Requirements and an Approach to Implementation
Authors: Ali Sy A. , Webb Holmes A.
Published: February 2015

The U.S. Department of Energy (DOE) is sponsoring a program to conduct design and development, leading to full scale demonstration of advanced gas turbine systems. The Advanced Turbine Systems (ATS) program is jointly administered by the DOE Office of Fossil Energy (DOE/FE) and the Office of Energy Efficiency and Renewable Energy (DOE/EE). The program will demonstrate commercial prototypes of both utility- and industrial-scale ATS by the year 2000.

The ATS program objectives are: system efficiency 60 percent (lower heating value [LHV]) or greater for utility-scale systems, and an equivalent 15 percent improvement for industrial systems; environmental superiority without the use of post combustion emissions controls; busbar energy costs 10 percent lower than current systems; adaptability to coal or biomass firing; and reliability, availability and maintainability equivalent to current advanced turbine systems.

A competitive procurement process is being used for the selection of contractors to develop and demonstrate full scale systems. System studies were completed by six U.S. turbine manufacturers, and awards were announced in August 1993 for “concept development.” This paper describes one implementation approach to achieve the DOE/ATS targets.
High Temperature Demonstration Unit for a 1500°C Class Gas Turbine
Authors: Sato M. , Matsuzakl H. , Yamaura T. , Aoki S. , Suanaga K. , Ito E. , Tomita Y.
Published: February 2015

Tohoku Electric Power Co., Inc. and Mitsubishi Heavy Industries, Ltd. have begun a joint development program on key technologies for a next generation gas turbine which aims for a combined cycle efficiency over 55%. Under the program, advanced cooling technologies, better heat resistant materials and thy low NOx (DLN) combustion technologies are being developed. For verifying high temperature technologies, turbine testing is going to be performed using the HTDU (High Temperature Demonstration Unit) at Takasago Machinery Works, Mitsubishi Heavy Industries, Ltd.

This paper describes the general description of the HTDU facility and plans for testing a turbine at a firing temperature of 1500°C.
The Simulation Methods in the Rotor-Machinery Diagnostics
Authors: Kicinski Jan , Drozdowski Robert
Published: February 2015

The paper presents some examples of simulation research carried out in view of large turbomachinery diagnostics. On the basis of computer simulations of some typical damages, such as “unbalanced” and hydrodynamic instability, it was possible to obtain the trajectories of the journal and the disc centre, as well as the amplitudes and the phase angles.

The paper refers to an example of two-point-supported rotor modelled using the Finite Element Method. The calculations were made on the basis of the complex elastodia-thermic model of the hydrodynamic slide bearing and also on the non-linear analysis of the system motion equations. The non-linear analysis made it possible to generate a characteristic vibration spectrum for every diagnostic relation. It refers especially to the computer simulations of the oil whirls and the oil whip, carried out for the various conditions of the rotor-machinery operation.
Multivariable Adaptive Control Using Only Input and Output Measurements for Turbojet Engines
Authors: Huang Jin-Quan , Sun Jian-Guo
Published: February 2015

Current and future aircraft engines are increasingly relying upon the use of multivariable control approach for meeting advanced performance requirements. A multivariable adaptive control (MRAC) scheme is proposed in this paper. The adaptation law is derived using only input and output (I/O) measurements. Simulation studies are performed for a two–spool turbojet engine. The satisfactory transient responses are obtained at different operating points from idle to maximum dry power within the flight envelope. These show insensitivity of the design to engine power level and flight condition. Simulation results also show high effectiveness of reducing interaction in multivariable systems with significant coupling. Using the multivariable MRAC controller, the engine acceleration time is reduced by about 19 percent in comparison with the conventional engine controller.
An Assessment of the Thermodynamic Performance of Mixed Gas-Steam Cycles: Part A — Intercooled and Steam-Injected Cycles
Authors: Macchi Ennio , Consonni Stefano , Lozza Giovanni , Chiesa Paolo
Published: February 2015

This paper discusses the thermodynamics of power cycles where steam or water are mixed with air (or combustion gases) to improve the performance of stationary gas turbine cycles fired on clean fuels. In particular, we consider cycles based on modified versions of modern, high-performance, high-efficiency aero-derivative engines.

The paper is divided into two parts. After a brief description of the calculation method, in Part A we review the implications of intercooling and analyze cycles with steam injection (STIG and ISTIG). In Part B we examine cycles with water injection (RWI and HAT).

Due to lower coolant temperatures, intercooling enables to reduce turbine cooling flows and/or to increase the turbine inlet temperature. Results show that this can provide significant power and efficiency improvements for both simple cycle and combined cycle systems based on aero-engines; systems based on heavy-duty machines also experience power output augmentation, but almost no efficiency improvement.

Mainly due to the irreversibilities of steam/air mixing, intercooled steam injected cycles cannot achieve efficiencies beyond the 52–53% range even at turbine inlet temperatures of 1500°C. On the other hand, by accomplishing more reversible water-air mixing, the cycles analyzed in Part B can reach efficiencies comparable (RWI cycles) or even superior (HAT cycles) to those of conventional “unmixed” combined cycles.
Unsteady Boundary Layers on a Flat Plate Disturbed by Periodic Wakes: Part II — Measurements of Unsteady Boundary Layers and Discussion
Authors: Funazaki K.
Published: February 2015

As the second part of the study, detailed hot-wire anemometry measurements of wake-affected boundary layers on the flat plate are made. These measurements are organized in order, first, to check the standpoint of the modeling of the wake-induced transition proposed in Part I, and second, to observe wake-boundary layer interaction in detail from a viewpoint of direct and indirect effect of the wake passage upon turbulent spot generation within the boundary layer, as described by Walker (1993).

The validity of the presumed state of the wake-affected boundary layer in the distance-time domain, which constitutes the basis of the transition model, is confirmed to great extent. However, it is also found that the criterion for the onset of the wake-induced transition adopted in Part I should be reconsidered. Some successful attempts are therefore made to specify the transition onset.
Measurement of Tip-Clearance Flow in a Multi-Stage, Axial Flow Compressor
Authors: Foley Andrew C. , Ivey Paul C.
Published: February 2015

Detailed measurements using pneumatic probe traverses, blade static pressure tappings and laser anemometry are made in the third stage of a large scale, low speed, four stage, axial flow, research compressor.

Inlet conditions show well ordered ‘two dimensional’ flow from approximately 40 to 85% annulus span. Outside of this region, reduced total pressure due to upstream leakage losses aod endwall effects results in high incidence to the following blade row. As a result, peak suction surface static pressure moves forward along the blade chord for both the huh and tip of stators and rotors. At the blade tip however, the peak suction pressure is maintained with chord due to radial flow on the suction surface being entrained into the tip leakage jet. The extent of rotor chord for which this ‘entrainment’ occurs increases with increasing rotor tip clearance gap. The leakage jet from both stators and rotors is seen to ‘roll up’ into a vortex downstream of their respective blade rows.
Simplified Models for NOx Production Rates in Lean-Premixed Combustion
Authors: Nicol David G. , Malte Philip C. , Steele Robert C.
Published: February 2015

Simplified models for predicting the rate of production of NOx in lean-premixed combustion are presented. These models are based on chemical reactor modeling, and are influenced strongly by the nitrous oxide mechanism, which is an important source of NOx in lean-premixed combustion. They include 1) the minimum set of reactions required for predicting the NOx production, and 2) empirical correlations of the NOx production rate as a function of the CO concentration. The later have been developed for use in an NOx post-processor for CFD codes. Also presented are recent laboratory data, which support the chemical rates used in this study.
Modeling of Local Extinction in Turbulent Flames
Authors: Sloan David G. , Sturgess Geoffrey J.
Published: February 2015

The Eddy Dissipation Concept (EDC), proposed by Magnussen (1985), advances the concept that the reactants are homogeneously mixed within the fine eddy structures of turbulence and that the fine structures may therefore be regarded as perfectly stirred reactors (PSRs). To understand more fully the extent to which such a sub-grid scale stirred reactor concept could be applied within the context of a computational fluid dynamics (CFD) calculation to model local or global extinction phenomena: (1) various kinetic mechanisms are investigated with respect to CPU penalty and predictive accuracy in comparisons with stirred reactor lean blowout (LBO) data and (2) a simplified time-scale comparison, extracted from the EDC model and applied locally in a fast-chemistry CFD computation is evaluated with respect to its capabilities to predict attached and lifted flames. Comparisons of kinetic mechanisms with PSR lean blowout data indicate severe discrepancies in the predictions with the data and with each other. Possible explanations are delineated and discussed. Comparisons of the attached and lifted flame predictions with experimental data are presented for some benchscale burner cases. The model is only moderately successful in predicting lifted flames and fails completely in the attached flame case. Possible explanations and research avenues are reviewed and discussed.