bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling of Accessories Power Demand at Low Power Regimes
Authors: Feja Anja , Banzhaf Bernd , Staudacher Stephan
Published: November 2008

Current jet engine architectures include accessories which are essential for the safe operation of the airframe and the engine itself. These accessories are mechanically linked to the turbo components via an external and internal gear box. The improved method for modeling accessories power demand at low power regimes which is proposed in this paper is applicable from zero speed up to maximum power setting. The accessories power demand is modeled as a function of engine power setting and aircraft configuration. Generalized models are available for the accessories groups which are mentioned above. It became necessary to model the engine heat management system as well since the fuel and oil temperatures have significant effect on the power needed by the affected accessories. The results achieved by this kind of accessories power demand modelling have been compared to corresponding values from the accessory components characteristics for a modern high performance aircraft jet engine. The model is implemented in an existing performance program and has been operated successfully.
Influence of the Swirler Design on the Flame Transfer Function of Premixed Flames
Authors: Hirsch C. , Fanaca D. , Reddy P. , Polifke W. , Sattelmayer T.
Published: November 2008

A novel approach to the description of flame transfer functions of premixed swirling flames is presented based on a simplified analysis of the vorticity transport equation. With this model it is possible to reproduce transfer function amplitude in excess of unity observed for swirling flames as well as to explain the differences seen in flame transfer functions for different swirler types. Measurements of flame transfer functions were performed on perfectly premixed flames generated by an axial and a radial swirler with an annular exit. Flames were adjusted as to achieve respective dynamic similarity. The comparison of the flame transfer functions shows the influence of the swirler type. Good agreement with the model validates the theoretical approach and allows to attribute the specific differences seen between the two swirler types with the generation of a swirl number modulation induced by the convective time delay between radial swirler and burner exit. The model also allows to explain the change of flame transfer function amplitude with pre-heating observed in previous publications.
Lost Thrust Methodology for Gas Turbine Engine Performance Analysis
Authors: Roth B. , de Luis J.
Published: November 2008

This paper presents and evaluates a lost thrust method for analysis of thermodynamic performance in gas turbine engines. This method is based on the definition of a hypothetical ideal engine that is used as a point of comparison to evaluate performance of the real engine. Specifically, component loss is quantified in terms of decrements in thrust of the real engine relative to the ideal engine having the same design point cycle. These lost thrust decrements provide a basis for accurately evaluating the performance cost of component losses while simultaneously accounting for all component interactions. The analysis algorithm is formally developed in detail and is then demonstrated for a typical separate flow turbofan engine. Various scenarios are examined and the results of these exercises are used to draw conclusions regarding the strengths and weaknesses of this approach to gas turbine performance analysis.
Probabilistic Matching of Turbofan Engine Performance Models to Test Data
Authors: Roth Bryce A. , Doel David L. , Cissell Jeffrey J.
Published: November 2008

This paper describes the development of an improved method for reliable, repeatable, and accurate matching of engine performance models to test data. The centerpiece of this approach is a minimum variance estimator algorithm with a priori estimates which addresses both deterministic and probabilistic aspects of the problem. Specific probabilistic aspects include uncertainty in the measurements, prior expectations on model matching parameters, and noise in the power setting parameters. The algorithm is able to produce optimal results using any number of measurements and model matching parameters and can therefore take advantage of all measured data to produce the best possible match. This improves on current matching algorithms which require that the number of measured parameters be equal to the number of model matching parameters. This algorithm has been implemented in the Numerical Propulsion System Simulation (NPSS) and tested on a generic high-bypass turbofan model typical of those used in commercial service. The baseline engine model and simulated test data are described in detail. Several exercises are discussed to illustrate results available from this algorithm including the matching of a typical power calibration data set and matching of a typical production engine data set.
Implementation of Engine Loss Analysis Methods in the Numerical Propulsion System Simulation
Authors: Roth Bryce A. , McClure Erin M. , Danner Travis W.
Published: November 2008

This paper describes the implementation and application of a new set of thermodynamic loss analysis tools in the Numerical Propulsion System Simulation. This analysis tool set is intended to enable fast, accurate estimation of losses in an engine cycle model with minimal effort on the part of the user. The basic thermodynamic concepts and analysis methods are first described. Next, the implementation of the necessary thermodynamic calculation functions is described. These functions are intended to be used in conjunction with a general-purpose loss analysis element to facilitate estimation of all losses in an engine cycle model. The loss analysis element is described in detail and is subsequently used to analyze a mixed flow turbofan engine. Typical performance and loss results are presented. The resultant detailed loss information is not normally available when using standard cycle analysis methods. The information gained from this analysis is useful in that it yields insight into the underlying losses that contribute to the overall engine performance.
Simulation of Engine Blade Tip-Rub Induced Vibration
Authors: Turner Kevin , Adams Maurice , Dunn Michael
Published: November 2008

An analysis has been developed to simulate the time-transient vibratory motion of a general configuration engine turbomachinery free-standing blade when subjected to in-service blade-on-casing tip-rub events. The analysis imports the at-speed stress-stiffened blade stiffness matrix and lumped mass matrix from a finite element model of the actual blade. Formulation and computational approaches are presented. Correct characterization of the blade tip-surface rub mechanics tribology models necessitates using empirical information that is currently being acquired from single-blade spin-pit tests now in progress in a parallel companion phase of this research. Output results for validation cases are presented. The analysis efficiently simulates complete transients involving multiple successive incursions (blade on casing hits), tracking the blade tip contact force distribution and blade motion throughout the simulated time frame including blade motion during, between and after successive casing hits.
Experimental Studies of the Primary Zone Flow Field and Combustion Performance of a Triple Swirler Combustor
Authors: Peng Yunhui , Xu Quanhong , Lin Yuzhen
Published: November 2008

Improvement of the lean blowout limit and more uniform combustor exit temperature distribution are particularly desirable for future aero engine. A triple swirler combination plus an airblast fuel injector might be a promising solution. The design with the triple swirler plus the airblast fuel injector including design A and B was presented and investigated in this paper. Single rectangle sector module combustor was used in the experiment for lean blowout (LBO), and three cups rectangle sector combustor was used for pattern factor (PF) experiments. The LBO and PF experiment data were provided. The primary zone flow field was measured by PIV (Particle Image Velocimetry) under atmospheric pressure and temperature. The result showed that the design A was a promising design, and the primary jet played very important role for flow field of primary zone. The insight relation between flow field and combustion performance could be found out from this paper.
Investigation of Combustion Performance of a Hybrid Airblast Atomizer Under Simulated Low Power Conditions
Authors: Gong Jing , Lin Yuzhen , Xu Quanhong , Liu Gaoen
Published: November 2008

An aero gas turbine combustor has to meet requirements for both high and low power condition operation. Within the requirements for low power conditions, lean-blow-out (LBO) and combustion efficiency are the basic ones. A pure prefilming air blast atomizer may have difficulty meeting combustion requirements under low power conditions, such as, idle LBO, idle combustion efficiency, etc. Use of a hybrid airblast atomizer may offer a solution for such problems. A hybrid airblast atomizer is a single fuel injection unit that has both pilot and main fuel circuits. A simplex nozzle is often used for pilot fuel circuit and an airblast atomizer of the swirl cup type may be used for the main fuel circuit. For the main fuel circuit, fuel is injected from a number of plain jet holes. The fuel jets are injected towards a venturi, with the help of swirling air from another air swirler, and the main fuel is airblasted and well mixed with both swirler airflows. For low power conditions, the pilot fuel nozzle (simplex nozzle) works alone. Not all of the swirler air will mix with pilot nozzle fuel spray. With appropriate pilot nozzle pressure drop and with some airblast function, the pilot fuel is well atomized and does not fully mix with the swirler air nor with primary hole air. Thus, the low power condition combustion efficiency is improved. The investigation reported in the present paper has concentrated on hybrid atomizer combustion performance under simulated low power conditions, when only the pilot nozzle is operating. The study consists of the following parts: • Pilot nozzle drop size measurement; • Numerical simulation of combustor flow field; • Atmospheric ignition test; • Simulated idle condition LBO test; • Low power condition combustion efficiency test. Results are reported, and future work is defined.
Unsteady Navier-Stokes Simulation of a Transonic Flutter Cascade Near Stall Conditions Applying Algebraic Transition Models
Authors: Thermann Hans , Niehuis Reinhard
Published: November 2008

Due to the trend in the design of modern aeroengines to reduce weight and to realize high pressure ratios, fan and first stage compressor blades are highly susceptible to flutter. At operating points with transonic flow velocities and high incidences stall flutter might occur involving strong shock-boundary layer interactions, flow separation and oscillating shocks. In this paper, results of unsteady Navier-Stokes flow calculations around an oscillating blade in a linear transonic compressor cascade at different operating points including near stall conditions are presented. The nonlinear unsteady Reynolds-averaged Navier-Stokes equations are solved time-accurately using implicit time-integration. Different Low-Reynolds-Number turbulence models are used for closure. Furthermore, empirical algebraic transition models are applied to enhance the accuracy of prediction. Computations are performed two-dimensionally as well as three-dimensionally. It is shown that, for the steady calculations, the prediction of the boundary layer development and the blade loading can be substantially improved compared with fully turbulent computations when algebraic transition models are applied. Furthermore, it is shown that the prediction of the aerodynamic damping in the case of oscillating blades at near stall conditions can be dependent on the applied transition models.
Numerical Study of Heat and Aerodynamic Processes in Regenerators of an Inert Gas Generator (IGG)
Authors: Kim SooYong , Kovalevski Valeri P. , Goldenberg V.
Published: November 2008

The cooling scheme for inert gas exhausting from a small gas turbine engine is presented and its performance, including the gas injector and regenerator, are investigated. A distributed, nonlinear mathematical model used to study the processes in regenerative heat exchangers is also described. An integral scheme of a conjugated problem of a non-stationary heat exchange of both one-dimensional streams and a two-dimensional matrix wall are presented. Comparison of test calculations made using the developed program with experimental data of different authors has shown satisfactory agreement. The extensive study results of quasistationary, dynamic heat and aerodynamic processes in regenerators with four types of matrices are introduced: ceramic matrix with straight rectangular cross-sectioned channels and three types of packings — granite full-spheres, Raschig rings and meshes of stainless steel. For each type of matrix, optimum range of rotation speeds ensures the maximum effectiveness while allowing the minimum aerodynamic resistance to be determined.
Turbo-Rotary Compound Engine (TRCE) and Novel Thermodynamic Cycle
Authors: Akmandor Ibrahim Sinan , Ercan Taylan , Karaca Mehmet
Published: November 2008

The present paper proposes a new turbo-rotary compound engine (TRCE) and an associated novel thermodynamic cycle. In this engine, shafts linking customary gas turbine engines components such as axial compressors and axial turbines are eliminated. Instead, two or multiple spools are lined up in series within the engine. In the front spool, partial admission rotary vane type turbines drive axial compressor stages. In the back spool, axial turbine stages drive partial admission rotary vane type compressors. Two air streams feed separately the customary turbo components and the rotary vane components, respectively. Accordingly, the primary high mass flow through the axial compressors and turbines is mainly responsible for the generation of net engine thrust and power, where as the secondary, low mass flow through the partial admission rotary components is mainly used to generate the internal energy required to power the axial compressor stages. The energy consumed internally by the engine is minimized because less input shaft power is needed for the rotary vane compressors and higher inlet temperatures and less cooling can be tolerated by the intermittent combustion rotary vane turbines. The result is a radical improvement in both efficiency and net power output. Aerothermodynamics and spool matching calculations comparing a T56-A14 core with a TRCE of similar size and compression ratio show that the new engine provides superior performance characteristics by increasing the net output work by 100% and decreasing the specific fuel consumption by 20%.
Advanced Environmental Barrier Coatings for SiC/SiC Composites
Authors: Bhatia Tania , Eaton Harry , Sun Ellen , Lawton Thomas , Vedula Venkat
Published: November 2008

Environmental barrier coatings (EBCs) are being developed for silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composites to protect against accelerated oxidation and subsequent silica volatilization in high temperature, high-pressure steam environments encountered in gas turbine engines. Engine testing of three-layer barium strontium aluminosilicate (BSAS) has demonstrated a life of over 15,000 hours in a combustor liner application at a nominal temperature of 2200°F (1204°C). The engine field tests have shown that useful engine life is limited by BSAS recession and potential eutectic reactions between BSAS and silica. BSAS based coatings have also been shown to survive severe thermal gradient burner rig tests with 2700°F (1482°C) surface temperature and a 300°F (167°C) gradient through the coating. Promising EBC candidates for longer life and/or higher temperature applications include strontium aluminosilicate (SAS) based coatings.
Thermodynamic Analysis of Turbofan Engine
Authors: Yadav R. , Jugseniya Chandrakant B. , Pashilkar Abhay A.
Published: November 2008

The present work deals with a detailed parametric thermodynamic analysis of all the possible configurations of turbofan engine (two and three spool with or without mixer and/ afterburner) employing transpiration cooling technique for turbine blade cooling. The study is focused on design point performance and is of general nature rather than an application specific parametric study. The analysis has been carried out by selecting/developing models for various components of engine. A computer program has been written which is capable of predicting engine dependent parameters (i.e. specific thrust, thrust specific fuel consumption, propulsive efficiency, efficiency of energy conversion and overall efficiency) at varying independent parameters at any flight condition and for any set of operating parameters. A set of multi-dimensional carpet plots predicting the effect of dependent in terms of independent parameters has been presented considering transpiration cooling for turbine blades and the temperature effect on specific heat of air/gas. Besides giving the comparative design point performance for a class of turbofan engine, these results could also be useful in assessing the relative benefits of extending technology to new engine configurations. Though, for a realistic mission application, the difference in performance at various thrust sizing conditions and at cruise conditions critical for fuel burn is a key characteristic in selecting the appropriate cycle, however this study could be useful in selecting in general the cycle configuration for a particular need with its optimum operating parameters.
Thermodynamic Study of Humid Air Gas Turbine Cycle Power Plants
Authors: Yadav R. , Yadav P. Sreedhar
Published: November 2008

The major challenges before the design engineers of a gas turbine plant and its variants are the enhancement of power output, substantial reduction in NOx emission and improvement in plant thermal efficiency. There are various possibilities to achieve these objectives and humid air gas turbine cycle power plant is one of them. The present study deals with the thermodynamic study of humid air gas turbine cycle power plants based on first law. Using the modeling and governing equations, the parametric study has been carried out. The results obtained will be helpful in designing the humid air gas turbines, which are used as peaking units. The comparison of performance of humid air gas turbine cycle shows that it is superior to basic gas turbine cycle but inferior and more complex to steam injected cycle.
Aero-Thermodynamic Model for Digital Simulation of Turbofan Engine
Authors: Yadav R. , Kapadi Yogesh , Pashilkar Abhay
Published: November 2008

The paper deals with the development and validation of an aero-thermodynamic model for a twin-spool mixed flow turbofan engine based on the state variable and control volume approach. Using actual performance data, the engine simulation has been performed for steady state and transient conditions with the help of MATLAB-SIMULINK. The simulation model is developed in a systematic manner. Engine states for different steady state operating conditions have been plotted. The model is fully equipped with capabilities to be integrated with the engine control design software to yield results for closed loop simulation. The results are validated against an independent and widely available modeling software called Gas turbine Simulation Program (GSP).
Development of the Full Authority Digital Engine Control (FADEC) System for the Enhanced TF40B Gas Turbine Engine on the U.S. Navy’s Landing Craft, Air Cushion (LCAC) Vehicles
Authors: Shappell Lance , Myers Lee , Yee Roger
Published: November 2008

The Landing Craft Air Cushion (LCAC) Service Life Extension Program (SLEP) upgrades the current main propulsion engine and analog control system to the Enhanced TF40B (ETF40B) gas turbine configuration with a Full Authority Digital Engine Control (FADEC) system. The FADEC system is an integral part of the ETF40B gas turbine configuration and interfaces with the new LCAC Control and Alarm Monitoring System (CAMS). In addition to increased reliability, the FADEC requires minimal maintenance and can provide uninterrupted engine diagnostic capabilities. The development of the FADEC system has been an ongoing effort among the Navy, Textron Marine & Land Systems (LCAC builder), Vericor Power Systems (ETF40B manufacturer), and Precision Engine Controls Corporation (PECC) (FADEC manufacturer). This paper will outline the FADEC development effort and the lessons learned during the design, environmental qualification, testing and operation for the LCAC.
Health Monitoring and Life Prediction of Thermal Barrier Coatings Using a Laser-Based Method
Authors: Visher Robert J. , Gast Luis , Ellingson William A. , Feuerstein Albert
Published: November 2008

Thermal barrier coatings (TBCs) are a critical component in low-emission gas turbines. A reliable method is required to monitor the condition of the TBC and predict coating failure. The condition of the interface between the metallic bond coat and TBC has been shown to be a potential indicator of spallation. The TBC is optically translucent; therefore, the bond coat/TBC interface can be probed using laser light with a wavelength of 0.632 microns or higher. A laser system in an optical backscatter configuration has been used to investigate several yttria-stabilized zirconia (YSZ) TBCs applied with either electron-beam physical vapor deposition (EB-PVD) or air plasma spraying (APS). The TBCs were thermally cycled for one hour increments until failure and investigated by the laser backscatter method after set numbers of thermal cycles. Correlations have been established between laser backscatter data and the number of thermal cycles, suggesting that the laser backscatter method can be used to predict failure. A theoretical model has been used to compare interface topography scatter to experimental results. This paper will discuss the laser backscatter technique and the experimental results and will compare the experimental data and theoretical scatter.
Advancements in Electrospun Nanofiber Technology Reduce Gas Turbine Compressor Fouling
Authors: Gahr Thomas C. , Benson James D. , Graham Kristine , Gogins Mark , Brown Michael
Published: November 2008

It is well established that sub-micron ambient aerosol contamination of the intake air can produce fouling of the gas turbine compressor and result in a reduction of power output. Application of electrospun nanofibers of 0.25 micron diameter to a conventional filter media substrate has been demonstrated to improve the efficiency of gas turbine intake filters to remove sub-micron contaminate. The benefits of nanofiber filtration have been proven through use in gas turbine intake air filtration and other industrial and defense filtration applications for over twenty years. Recent advancements in electrospun nanofiber media technology have increased the filtering efficiency of gas turbine intake filters, with minimal differences in filter element pressure loss. These advances have also improved the durability of nanofibers in high temperature and high humidity applications. This paper discusses the laboratory testing that demonstrates these performance and durability improvements. A comparative field test program demonstrates the capability of nanofiber filtration to significantly reduce the fouling of gas turbine compressors.
Development of Detailed Kinetic Mechanism to Study Low Temperature Ignition Phenomenon of Kerosene
Authors: Gokulakrishnan P. , Klassen M. S. , Roby R. J.
Published: November 2008

The objective of this work is to develop a detailed kinetic mechanism for low temperature kerosene oxidation, which is essential to predict premature auto-ignition of liquid fuels in gas turbines and cool flame behavior in hydrocarbon reformers for fuel cells. Kerosene, a fractional distillate of petroleum known by its generic term, is comprised of a wide range of aviation fuel grades such as Jet A, Jet-4, JP-8 etc, with a chemical composition varying from higher order n-alkanes to complex aromatics. Thus, developing a detailed kinetic mechanism to represent actual kerosene is not only cumbersome but also computationally intensive to implement. Therefore, very often a surrogate mixture with known chemical composition is devised to study kerosene oxidation. In this work, a hierarchical structure of the kerosene mechanism with approximately 1400 reactions of 550 species is developed using a surrogate mixture of n-decane, n-propylcyclohexane and n-propylbenzene to represent major components of kerosene, namely n-alkanes, cyclo-alkanes and aromatics, respectively. Since a major portion of the kerosene consists of very reactive n-alkanes rather than the less reactive ring structures, the low temperature oxidation kinetics is predominantly dictated by n-alkanes. Thus, the modeling effort is mainly focused on developing a low temperature mechanism for n-decane. The low-temperature oxidation of the individual fuel of the surrogate mixture, especially n-decane, was fairly well-characterized experimentally in shock-tubes and flow-reactors, and hence, the mechanism is validated against the available experimental measurements. With the objective of achieving a more comprehensive mechanism, the model validation is extended to include target data for wide range of conditions including high pressure and high temperature experimental data available in the literature. The model predictions of the kerosene mechanism were compared to the available experimental data on ignition delay time as well as the reactivity species profiles of different aviation grade fuels obtained in flow reactors. The predictions of the kerosene mechanism agree with the experimental data fairly well especially at low to intermediate temperature regimes. A sensitivity analysis was performed to identify the rate-limiting steps at low, intermediate and high temperatures. It was observed that reactions involving ketohydroperoxides and hydrogen-peroxides are the most important reactions at low and intermediate temperatures, respectively.
Improved Quality Assessment for Turbine Engine Components With Potential Applications to Ceramic Matrix Composite (CMC) Materials
Authors: Akers D. W. , Rideout C. A.
Published: November 2008

Demand for improved power from turbine engines has resulted in the development of ceramic matrix composite (CMC) materials that can withstand extreme temperature environments and maintain the damage tolerance required for space vehicles and next generation turbine engines. CMC components allow higher temperature operation and increased power over nickel-based superalloy components due to their reduced weight and temperature stability. The use of CMCs allows a potential increase in turbine engine temperatures to above 1400°C. This temperature increase results in improved performance, which translates into increased efficiency, better power to weight ratios, and improved reliability with both significant fuel savings and reduced life cycle costs. Evaluating CMC component quality is difficult due to variations in the fiber/matrix properties and variations in fabrication related parameters. Further, there is limited information on operational and remaining life characteristics. These factors produce significant challenges to existing inspection methods. Determining the reliability of CMC components is a complex process and requires an understanding of both manufacturing variability and damage effects that can occur throughout the life of the component. Consequently, a nondestructive inspection capability is required that can reliably evaluate CMC components during manufacturing, provide acceptance/rejection criteria for determining “fitness for use” and be useful for assessing operational damage effects. New nondestructive testing capabilities, Photon Induced Positron Annihilation (PIPA) and Distributed Source Positron Annihilation (DSPA), have demonstrated the potential ability to detect and quantify fabrication flaws and manufacturing quality for metallic, composite and ceramic components that are used to improve performance and power to weight ratios in high temperature turbine engine applications.
Aerothermodynamic Design and Numerical Simulation of Radial Inflow Turbine Impeller for a 100kW Microturbine
Authors: Feng Zhengping , Deng Qinghua , Li Jun
Published: November 2008

The high aerodynamic performance, strength reliability and vibration reliability are three aspects of radial inflow turbine impellers design. This paper mainly presents an investigation on the first aspect but take into account the strength evaluation for a 100kW microturbine unit. Firstly, a thermodynamic design of the radial inflow turbine is carried out, and some important parameters are obtained. Then, the traditional cylinder parabolic geometrical design method is applied to the impeller design. The results of FEM evaluation show the impeller’s maximum stress exceeds the limitations of the impeller material, and the magnitude of centrifugal stress has distinct difference between the suction and the pressure side at the impeller hub. Therefore, a positive axial displacing method and its combination with skewing technique are proposed and developed to solve the strength problem, and the final impeller is designed with inlet relative flow incidence angle of the impeller reaches −32 degree from the radial direction. The numerical analyses using FEM and CFD codes indicate that the final designed impeller satisfies the strength requirements and shows good aerodynamic performance. Furthermore, a 3D Navier-Stokes solver is applied to evaluate the aerodynamic performance of the radial inflow turbine under stage environment and to investigate the detailed flow characteristics of the final designed impeller. As a result, the radial inflow turbine of 100kW microturbine unit has high aerodynamic performance with good consideration on the terms of turbine structure and stress limitations.
Assessment of Technologies for Biomass Conversion to Electricity at the Wild Land-Urban Interface
Authors: Green Alex , Feng Jie
Published: November 2008

In the near term, biomass in various forms is the most available renewable energy source in the USA, particularly in the wild land-urban interface (WUI). With current high natural gas (NG) prices the possibility of gasifying biomass and developing a local Biomass Alliance with Natural Gas (BANG) so that the biomass gas (BG) can supplement natural gas (NG) could have many energy, environmental and economic (EEE) benefits. An analytic cost estimation (ACE) method is used to assess various BANG technologies potentially applicable at the WUI and to determine NG prices at which BG capable systems can deliver electricity at competitive costs. ACE is based upon the approximate linear relationship between cost of electricity (COE = Y), and cost of fuel (COF = X), i.e., Y = K + SX, as seen in many detailed cost analyses of electrical generating systems. ACE is here used to guide efforts directed towards energy sustainability in the WUI where nearby biomass stores are abundant. Thermal conversion and the use of the fuel to supplement NG is considered here at various power (P) levels to lower the cost of electricity. A reasonable K(P) and S(P) for NG fired electrical generation systems is first established. Then using an Antares Group Inc. report (AGIR) analyses of eleven biomass fueled technologies K(P) and S(P) are identified using only three adjusted parameters for each technology. An accurate analytical equation is also found for AGIR calculations of net present value (NPV = Z) vs. P and Y. These equations are then used to interpolate and extrapolate the AGIR economic analyses to other Ps and X or Y in some cases leading to other conclusions than in the AGIR. We conclude that BANG can save energy costs in many communities at the WUI and lead the way to: the development of economically competitive woody biomass supply and applications industries provide jobs, stabilize local economies, reduce USA’s dependence on imported fuels and lower greenhouse gas emissions.
Experimental Response of a Rotor Supported on Rayleigh Step Gas Bearings
Authors: Zhu Xuehua , San Andre´s Luis
Published: November 2008

Reliable gas bearings will enable the rapid deployment of high speed oil-free micro-turbomachinery. This paper presents analysis and experiments of the dynamic performance of a small rotor supported on Rayleigh step gas bearings. Comprehensive tests demonstrate that Rayleigh step hybrid gas bearings exhibit adequate stiffness and damping capability in a narrow range of shaft speeds, up to ∼ 20 krpm. Rotor coast down responses were performed with two test bearing sets with nominal radial clearance of 25 μm and 38 μm. A near-frictionless carbon (NFC) coating was applied on the rotor to reduce friction at liftoff and touchdown. However, the rotor could not lift easily and severe rubbing occurred at shaft speeds below ∼ 4,000 rpm. The tests show that the supply pressure raises the rotor critical speed and decreases the system damping ratio, while only affecting slightly the rotor-bearing system onset speed of instability. Whirl frequencies are nearly fixed at the system natural frequency (∼ 120 Hz) with subsynchronous amplitude motions of very large magnitude that prevented rotor operation above ∼ 20 krpm. The geometry of the Rayleigh steps distributed on the rotor surface generates a time varying pressure field, resulting in a sizable 4X super synchronous component of bearing transmitted load. Predictions show the synchronous stiffness and damping coefficients decrease with shaft speed. Predicted threshold speeds of instability are much lower than measured values due to the analytical model limitations assuming a grooved stator. The predicted synchronous responses to imbalance correlate well with the measurements. The Rayleigh step gas bearings are the most unreliable rigid bearing configuration tested to date.
Integrated In-Flight Fault Detection and Accommodation: A Model-Based Study
Authors: Rausch Randal T. , Goebel Kai F. , Eklund Neil H. , Brunell Brent J.
Published: November 2008

In-flight fault accommodation of safety-critical faults requires rapid detection and remediation. Indeed, for a class of safety critical faults, detection within a millisecond range is imperative to allow accommodation in time to avert undesired engine behavior. We address these issues with an integrated detection and accommodation scheme. This scheme comprises model-based detection, a bank of binary classifiers, and an accommodation module. The latter biases control signals with pre-defined adjustments to regain operability while staying within established safety limits. The adjustments were developed using evolutionary algorithms to identify optimal biases off-line for multiple faults and points within the flight envelope. These biases are interpolated online for the current flight conditions. High-fidelity simulation results are presented showing accommodation applied to a high-pressure turbine fault on a commercial, high-bypass, twin-spool, turbofan engine throughout the flight envelope.
Strength Design and Numerical Analysis of Radial Inflow Turbine Impeller for a 100kW Microturbine
Authors: Xie Yonghui , Deng Qinghua , Zhang Di , Feng Zhenping
Published: November 2008

Microturbines usually require a type of radial inflow turbine due to the need for high efficiency under the condition of small mass flow rate and compact geometry. This paper describes the strength design for a 320kW radial inflow turbine impeller during the research and development of 100kW class microturbine. The turbine has a high rotating speed up to 61000rpm and its inlet gas temperature reaches 900°C. Firstly, conventional method is adopted to design the impeller, but the maximum stress predicted by Finite Element Analysis (FEA) greatly exceeds the yield limit of material. In order to satisfy strength requirement of the impeller, the thickness, the inlet and outlet angles of blade in impeller are taken as parameters to optimize its geometry. Meanwhile, aerodynamic performance of blade and factors of manufacture are taken into account. With the aid of numerical analysis and optimization, an optimal impeller is obtained with a very low maximum stress of 651MPa, which can satisfy the strength requirement of the working impeller. The FEA results also show that the optimization method developed in this paper is a successful one, it can not only provide an optimal geometry for impeller and decrease its apparent stress, but also be much useful for strength design of other components of the machines. At last, aerodynamic performance of optimal impeller is analyzed by CFD and the numerical results shows it is satisfactory design.
The Use of a Second-Generation Expert System Based on “Case-Based Reasoning” for the Operational Support of Gas Turbine-Based Power Plants
Authors: Decoussemaeker Pascal
Published: November 2008

The increased complexity of power plants is driving companies to look for ways to effectively capture and re-use know-how acquired in the form of experience made by personnel involved in troubleshooting. In recent years, there has been much progress in the fields of knowledge management in general, and artificial intelligence in particular. One such technology with its roots in cognitive psychology is called case-based reasoning. This paper begins with an overview of the organizational knowledge creation process in general, a description of a technology called case-based reasoning, and an analysis of the advantages of case-based reasoning compared to more classic knowledge-based systems. It then describes what is at stake in the maintenance of mission-critical, high-technology equipment in the power industry, followed by a description of a second-generation expert system based on case-based reasoning that is designed to effectively capture and reuse troubleshooting knowledge within a large organization. Finally, it will illustrate other issues that can be addressed, such as staff turnover, availability of experts, etc..
Airblast Swirl Atomizer for Small Jet Engines
Authors: Levy Y. , Sherbaum V. , Levin D. , Ovcharenko V.
Published: November 2008

The current work presents a study of an air blast simplex atomizer which supplies air to the fuel spray through radial channels for liquid film dispersing. The performance of two atomizer configurations using either co-rotating or counter-rotating liquid and air flows was investigated. The change in the direction of liquid swirl was achieved by replacing the inner swirler with a similar one having the holes drilled on the opposite side. Atomizer flow number FNSI in the experiments was 0.74·10−7. The study has shown that droplet size reduces significantly when the air velocity grows up to 60 m/s but further increase in air velocity has almost no effect on the droplet size. In the absence of air supply the increase in liquid pressure leads to the decrease of Sauter mean diameter (SMD) of droplets from 85 to 60 μm. However, in the air blowing regime the liquid pressure has only slight effect on SMD rising it from 30 to 40 μm. Better atomization performance has been obtained in the case of co-rotation atomizer.
Study of Infrared CO2 Radiation From Liquid-Fueled Combustor
Authors: Levy Y. , Lev M. , Ovcharenko V.
Published: November 2008

Measurements of CO2 infrared radiation were performed on exhaust gases from a combustor. The combustor is a 30% flat (rectangular) model of an annular turbojet-engine combustion chamber. This is a turbulent non-premixed kerosene-air flame with equivalence ratios within the range of 0.15–0.75. The infrared radiation images are obtained by a IR camera equipped with a narrow bandpass filter that falls on the CO2 fundamental band. Temperature profiles were measured by thermocouple at the combustor outlet. The INFRAD program was used to calculate infrared radiation from the CO2 gas component of the exhaust gases from the combustor. The simulation was performed, taking into account the effects of radiation emission and absorption along an optical path. The calculations allow prediction of apparent gas temperatures using the IR camera readings. The calculated results are compared with experimental measurements. They are found to be in reasonable agreement.
Jet Engine Component and Transducer Fault Diagnosis Using an Inverse Dynamic Model
Authors: Lichtsinder M. , Levy Y.
Published: November 2008

Engine component and transducer degradation/fault diagnosis, are analyzed. The analysis is performed using an aero-thermodynamic nonlinear inverse jet-engine model while using data acquired during transient engine operation. A shortened inverse jet-engine model (without one or more engine component maps) was recently proposed by the authors for real-time simulations and for fast evaluation of engine component maps. The algorithm for the engine component’s fault diagnosis is significantly simplified using shortened inverse engine models. A diagnostic example of combined faults of a single transducer and a single engine component for a single spool jet engine is described using different combinations of shortened inverse jet engine models. In the present paper it is assumed that only a single transducer (out of the seven transducers) and /or a single engine component (compressor or turbine) fault could be present in the engine at a given time.
Fundamentals of Low-NOx Gas Turbine Adiabatic Combustor
Authors: Levy Y. , Sherbaum V. , Erenburg V.
Published: November 2008

The present work is concerned with the thermodynamic, chemical and geometric parameters of gas turbine combustor operating in the flameless oxidation combustion regime. A methodology for calculating the thermodynamic parameters was developed for adiabatic combustion with recirculation. This enables to find the oxygen concentration, temperatures and other principal combustion products at different operational combustion conditions and to obtain geometrical relationships of the combustor. Based on shock-tube tests and comparison with CHEMKIN code simulations, a methodology to estimate the heat density generation at the recirculation zone was elaborated. These results have enabled preliminary design of the combustor and two sector models (60 degrees each) were produced. The combustor sectors were tested and demonstrated very stable combustion operation over a wide range of equivalence ratios with low NOx emission.
Nanoscale Thermoelectric Applications for Marine Gas Turbine Engines
Authors: Nicolo James J. , Zipkin David M.
Published: November 2008

A nanoscale thermoelectric module, applied in the form of a coating or panel or tiled array, could translate the thermal waste heat produced by gas turbine generators onboard United States Naval Vessels into various ship-board applications. The gross temperature differences that exist in engine enclosures and exhaust ducting provides an excellent potential gradients for such an application; and the energy produced from such an application could then be used to provide a vast array of engineering services to be discussed in this paper.
An Intermediate Approach to Communcation and Sensor Interfacing Standardization for Marine Gas Turbine Engines
Authors: Nicolo James J. , Zipkin David M. , Scharschan John
Published: November 2008

This paper details the on-going effort of NAVSEA Philadelphia to provide a command and control technology upgrade to the Model 139 Gas Turbine Generator Set, while deploying a novel approach to this process using Open System Architecture Condition Based Maintenance (OSA-CBM) archetype. The long-term goal of the process being implemented is to serve as the foundation for a communication and interfacing standardization for the marine gas turbine (GT) community. The topics to be discussed in this essay span from investigation to a proposed design, which includes physical measurement of parameters, sensor-Full Authority Digital Controller (FADC) interfacing, and overall system architecture.
Development of Parametric Mass and Volume Models for an Aerospace SOFC/Gas Turbine Hybrid System
Authors: Tornabene Robert , Wang Xiao-Yen , Steffen Christopher J. , Freeh Joshua E.
Published: November 2008

In aerospace power systems, mass and volume are key considerations to produce a viable design. The utilization of fuel cells is being studied for a commercial aircraft electrical power unit. Based on preliminary analyses [1, 2], a SOFC/gas turbine system may be a potential solution. This paper describes the parametric mass and volume models that are used to assess an aerospace hybrid system design. The design tool utilizes input from the thermodynamic system model and produces component sizing, performance and mass estimates. The software is designed such that the thermodynamic model is linked to the mass and volume model to provide immediate feedback during the design process. It allows for automating an optimization process that accounts for mass and volume in its figure of merit. Each component in the system is modeled with a combination of theoretical and empirical approaches. A description of the assumptions and design analyses is presented.
Gas Turbine Fogging Technology — A State-of-the-Art Review: Part I — Inlet Evaporative Fogging, Analytical and Experimental Aspects
Authors: Bhargava R. K. , Meher-Homji C. B. , Chaker M. A. , Bianchi M. , Melino F. , Peretto A. , Ingistov S.
Published: November 2008

Ambient temperature strongly influences gas turbine power output causing a reduction of between 0.50% to 0.90% for every 1°C of temperature rise. There is also a significant increase in the gas turbine heat rate as the ambient temperature rises, resulting in an increased operating cost. As the increase in power demand is usually coincident with high ambient temperature, power augmentation during the hot part of the day become important for independent power producers, cogenerators and electric utilities. Evaporative and overspray fogging are simple, proven and cost effective approaches for recovering lost gas turbine performance. A comprehensive review of the current understanding of the analytical and experimental and practical aspects of high-pressure inlet fogging technology is provided. A discussion of analytical and experimental results relating to droplet dynamics, factors affecting droplet size, and inlet configuration effects on inlet evaporative fogging are covered in this paper. Commonly used fogging nozzles are also described and experimental findings presented.
Gas Turbine Fogging Technology — A State-of-the-Art Review: Part II — Overspray Fogging, Analytical and Experimental Aspects
Authors: Bhargava R. K. , Meher-Homji C. B. , Chaker M. A. , Bianchi M. , Melino F. , Peretto A. , Ingistov S.
Published: November 2008

The strong influence of ambient temperature on the output and heat rate on a gas turbine has popularized the application of inlet fogging and overspray for power augmentation. One of the main advantages of overspray fogging is that it enhances power output as a result of decrease in compression work associated with the continuous evaporation of water within the compressor due to fog intercooling. A comprehensive review on the current understanding of the analytical and experimental aspects of overspray fogging technology as applied to gas turbines is presented in this paper.