bluuebunny/crossref_metadata_2025 huggingface dataset:
Accelerated Industrial Blade Design Based on Multi-Objective Optimization Using Surrogate Model Methodology
Authors: Keskin A. , Swoboda M. , Flassig P. M. , Dutta A. K. , Bestle D.
Published: August 2009

The intention of this paper is to provide an advanced aerodynamic blade design approach for industrial purposes which are basically characterized by limited development time, human and computing resources. From the industrial point of view, the demand for process acceleration and design optimization cannot be sufficiently satisfied with traditional human-based design methods. Recent investigations on blade optimization have shown some potential in performance improvements, however, this is typically obtained by high computational efforts in particular when using multi-objective optimization methods. In order to combine the benefits of numerical optimization with the requirements of industrial needs for design acceleration, a new automated blade optimization strategy is required. The accelerated industrial blade design process in this paper is based on a three-dimensional parameterization approach using non-dimensional parameter distributions which always guarantee desired blade geometry smoothness. In order to approximate the design objectives and constraints, a response surface methodology is applied where the design parameter variation is obtained by the quasi-random SOBOL sequence. Based on that, a highly sophisticated multi-objective genetic algorithm is used with reasonable numbers for individuals and generations for solving the contradicting design goals of an aerodynamic blade design problem by considering multiple aerodynamic and geometric constraints. This approach offers a set of non-dominated solutions on the Pareto-front which are subsequently evaluated with the exact flow analysis. In case of objective function value discrepancies between model and exact evaluations, an update of the surrogate model is performed including these additional solutions until the approximation response is equivalent to the exact analysis within a predefined tolerance. This new methodology shows a significant overall design time reduction particularly a decrease of required function evaluations without loosing the benefit of multi-objective optimization in providing Pareto-optimal solutions. Based on a typical industrial compressor test case, an aerodynamic performance improvement and process acceleration by factor greater than 10 could be achieved.
Validation of Steady Average-Passage and Mixing Plane CFD Approaches for the Performance Prediction of a Modern Gas Turbine Multistage Axial Compressor
Authors: Mansour Mahmoud L. , Gunaraj John , Goswami Shraman
Published: August 2009

This paper summarizes the results of a validation and calibration study for two modern Computational Fluid Dynamics programs that are capable of modeling multistage axial compressors in a multi-blade row environment. The validation test case is a modern 4-stage high pressure ratio axial compressor designed and tested by Honeywell Aerospace in the late 90’s. The two CFD programs employ two different techniques for simulating the steady three-dimensional viscous flow field in a multistage/multiblade row turbo-machine. The first code, APNASA, was developed by NASA Glenn Research Center “GRC” and applies the approach by Adamczyk [1] for solving the average-passage equations which is a time and passage-averaged version of the Reynolds Averaged Navier Stokes (RANS) equations. The second CFD code is commercially marketed by ANSYS-CFX and applies a much simpler approach, known as the mixing-plane model, for combining the relative and the stationary frames of reference in a single steady 3D viscous simulation. Results from the two CFD programs are compared against the tested compressor’s overall performance data and against measured flow profiles at the leading edge of the fourth stator. The paper also presents a turbulence modeling sensitivity study aimed at documenting the sensitivity of the prediction of the flow field of such compressors to use of different turbulence closures such as the standard K-ε model, the Wilcox K-ω model and the Shear-Stress-Transport K-ω/SST turbulence model. The paper also presents results that demonstrate the CFD prediction sensitivity to modeling the compressor’s hub leakages from the inner-banded stator cavities. Comparison to the test data, using the K-ε turbulence closure, show that APNASA provides better accuracy in predicting the absolute levels of the performance characteristics. The presented results also show that better predictions by CFX can be obtained using the K-ω and the SST turbulence models. Modeling of the hub leakage flow was found to have significant and more than expected impact on the compressor predicted overall performance. The authors recommend further validation and evaluation for the modeling of the hub leakage flow to ensure realistic predictions for turbo-machinery performance.
A New Fluid Film Bearing Test Rig for Oil and Water Bearings
Authors: Dimond Tim , Rockwell Robert D. , Sheth Pradip N. , Allaire Paul E.
Published: August 2009

Ever-increasing demands on the turbomachinery industry result in faster, lighter machines with higher rotational speeds and power densities. Modern, well-established thermoelastohydrodynamic (TEHD) analyses predict static and dynamic bearing characteristics in the presence of a turbulent lubricant and reduced lubricant flows. Proper design of tilting-pad journal bearings (TPJB) is required for successful operation of rotating machinery. Bearing static effects include pad temperature, bearing pressure profile, and static operating position. Bearing dynamic effects include stiffness, damping, and added mass coefficients. The current body of experimental data does not include the entire range of speed and load for which TEHD analyses are thought to be valid or where industrial machines operate. Experimental data for both oil-lubricated and water-lubricated bearings is desired. Oil lubricated bearings are used in high-speed turbomachinery. Water bearing data are of interest for applications that use the process fluid as the bearing lubricant. This paper describes a new Fluid Film Bearing Test Rig (FFBTR) which is being designed to experimentally verify the TEHD analyses, both in the laminar and in the turbulent regime, and support industrial needs. Static bearing characteristics will be measured with temperature probes, pressure probes, and displacement measurements. The dynamic bearing coefficients will be identified by rotor perturbation with active magnetic bearing force actuators. The rotational speed range of the FFBTR will be 9000–22000 rpm. The test bearing size is 127 mm, giving a range of surface speeds of 60–146 m/s. The range of bearing length-to-diameter (L/D) ratios that can be tested will be 0.5–0.75. Separate lubrication systems for water-lubricated and oil-lubricated bearings will be provided. Two magnetic bearings will be used as non-contact force actuators for rotorbearing system perturbation. The designed capacity for the magnetic force actuators is 13 kN/exciter, for a total static plus dynamic load of 26 kN that can be applied to the test bearing. The actuators are designed to apply forces to the test rotor at non-synchronous frequencies up to 560 Hz. Bearing static characteristics will be measured. Static measurements will include lubricant pressure profile, lubricant and pad temperatures, and static eccentricity. During dynamic testing, test shaft and bearing tilting pad motion will be measured. Dynamic bearing stiffness, damping, and added mass coefficients will be identified from force and displacement measurements. The frequency dependence in tilting-pad journal bearing coefficients will be investigated. The combination of static and dynamic measurements will be used to validate the TEHD analyses and provide design information to industry.
The Engine 3E Core Engine
Authors: Klinger Holger , Lazik Waldemar , Wunderlich Thomas
Published: August 2009

Engine 3E is the aero engine part of the German Aeronautics Research Program under which Rolls-Royce Deutschland developed key technologies for an all new core engine that incorporates major advances with regard to environmental friendliness, efficiency and economy. The derived E3E core engine will serve as a scalable baseline for the future two-shaft engine family in the medium take-off thrust range between 12 – 40 klb. The core consists of a highly loaded 9-stage HPC, a lean burn combustion chamber with internal fuel staging and a 2-stage shroudless HPT. On the basis of its high specific power, low NOx combustion and low manufacturing cost, it will enable significant improvements in SFC, emissions, unit cost and weight. The related technology demonstrator is currently in the final build and instrumentation phase for testing in an altitude test facility in first quarter 2008.
Computational Aerodynamic Performance on Radial and Mixed-Flow Design Options for a High Specific Speed Turbine
Authors: Oh JongSik , Buckley Charles W. , Agrawal Giri L.
Published: August 2009

Aerodynamic performance of three turbines with an identical nozzle vane is numerically investigated, which were designed for a high specific speed operating condition in marine ship engine turbochargers; one radial-inflow rotor and two mixed-flow rotors, in which only inlet configurations of the rotor are different. Using a three dimensional compressible turbulent CFD, general performance parameters are computed for pressure ratios from 2 to 10 at constant speed and constant inlet conditions, with the Stage interaction between the nozzle and the rotor domains. Overall total-to-static and total-to-total efficiencies are examined for various pressure ratios and various blade speed ratios. Flow angles and Mach number distributions at rotor inlet and exit are studied for different shapes of rotor inlet geometry. Three dimensional streamlines inside each rotor at high specific speed conditions show how the secondary flow is developed and constructed near hub, and which configuration of the rotor inlet is promising in aerodynamic point of view.
Control Performance Study on the Molten Carbonate Fuel Cell Hybrid Systems
Authors: Zhang Huisheng , Wang Lijin , Weng Shilie , Su Ming
Published: August 2009

The intention of this work is to investigate the control characteristics of molten carbonate fuel cell hybrid systems through dynamic simulation. Because of the complexity and interaction between different components in the hybrid systems, several parameters, such as the turbine rotational speed, the temperatures within the fuel cell, the differential pressure between the anodic and the cathodic side, the steam-to-carbon ratio, need to be monitored and kept within safe limits. On the other hand, the system response to load variations is required to be as quick as possible in order to meet the energy demand. Several control loops were introduced into the hybrid system, the paper focuses on the control performance to regulate the net electrical power from the hybrid system, avoiding malfunctions or damage. The results for several operating conditions are presented and discussed.
Optimization Design of the Geared Rotor System With Critical Speed Constraints Using the Enhanced Genetic Algorithm
Authors: Shiau T. N. , Kang C. H. , Liu D. S. , Lee E. K. , Hsu W. C.
Published: August 2009

This paper presents an efficient enhanced genetic algorithm to minimize the shaft weight, the unbalance response and the response due to the transmission error simultaneously. The minimization plays an important role in designing the geared rotor system under critical speed constraints. In the process of optimization, the design variables consist of shaft inner radii, bearing stiffness and the gear mesh stiffness. The enhanced genetic algorithm of optimization comprises the Hybrid Genetic Algorithm (HGA) and the Interval Genetic Algorithm (IGA). The HGA deals with this optimal design problem and the IGA accomplishes the interval optimization design. The results show that the presented enhanced genetic algorithm can not only effectively reduce the shaft weight and the transmission error response, but also precisely determine the interval ranges of design variables with feasible corresponding objective error.
3D Thermoacoustic Properties of Single Can and Multi Can Combustor Configurations
Authors: Kaufmann Peter , Krebs Werner , Valdes Richard , Wever Utz
Published: August 2009

Evaluation of thermoacoustic properties of gas turbine combustion systems during the design phase is crucial to meet time to market requirements for advanced new gas turbines. During the design phase the impact of design changes on engine performance need to be assessed although testing at full scale engine configuration is not possible. In this context a 3D thermoacoustic stability code has been developed providing thermoacoustic stability of combustion systems in rig and engine environments. The code has been applied to can combustion systems utilized by SIEMENS in the latest brand the SGT5-8000H which was successfully first fired in December 2007. While the flame stabilization within can combustors can be realized in single rig systems identical to engine configurations the acoustic environment of test rig and engine will differ due to the can-to-can interaction in multi-can systems. The features of the SIEMENS code are outlined and the successful application to single can and multi can configurations is demonstrated by comparison to experimental data. This provides SIEMENS with the prediction of thermoacoustic stability of respective engine configurations.
A Comparative Analysis of Pressure Side Extensions for Tip Leakage Control in Axial Turbines
Authors: Shavalikul Akamol , Camci Cengiz
Published: August 2009

Pressure side extensions are effective tip leakage control devices in axial flow turbines. RANS based viscous flow simulations are used to compare a number of potential aerodynamic de-sensitization devices for blade tips. The present study benefits from the past aerodynamic experiments performed in the rotating turbine rig at Penn State by Dey and Camci [14]. After a brief discussion of the computational details, a grid independency study is presented. The current study shows that a significant tip leakage mass flow rate and aerodynamic loss reduction is possible by using proper tip platform extensions located near the pressure side corner of the blade tip. A set of computations with realistic turbine rotor inlet flow conditions are performed in a linear cascade arrangement in the relative frame of reference. The boundary conditions for the computations are obtained from inlet flow measurements performed in Penn State Axial Flow Turbine Research Facility AFTRF.
Nonlinear Vibration Analysis of Gas Turbine Bladings With Shroud Coupling
Authors: Hohl Andreas , Siewert Christian , Panning Lars , Kayser Andreas
Published: August 2009

Rotating blades are subjected to vibrations caused by excitation forces due to a non-homogeneous pressure field of the fluid. Therefore, damping devices like tip shrouds are implemented which reduce the vibrational amplitude and apply additional stiffness and damping to the structure. To predict the resulting vibration response and stresses, a three dimensional contact model has been developed to determine the friction forces. The resulting equations of motion are solved in the frequency domain. The developed method has been implemented in a nonlinear forced response code called DATAR designed for the gas turbine division of Siemens Energy. In this paper, the transfer of common Finite Element models of bladings with shrouds or underplatform dampers to the DATAR code is presented. A mapping procedure based on Finite Element shape functions is used to couple the model with the regular contact grid used in the nonlinear vibration analysis performed with the DATAR code. As a practical example, the vibration behavior of a gas turbine blading with interlocked shrouds is investigated with the developed method.
Influence of Wake Structure on Unsteady Flow in an LP Turbine Blade Passage
Authors: Sarkar S.
Published: August 2009

The effect of wake structures on the evolution of the boundary layer over the suction side of a high-lift low-pressure turbine is studied using large-eddy simulation (LES) for a Reynolds number Re = 7.8×104 (based on the axial chord and inlet velocity). The wake data of different characteristics (defined by the wake deficit and the small-scale motion) are extracted from a precursor LES of flow past a cylinder. This replaces a moving bar that generates wakes in front of a cascade. LES results illustrate that apart from the wake kinematics, the large pressure oscillations and rollup of the separated shear layer along the rear half of the suction surface depend on the length scale of the convective wake. The transition of this rolled-up shear layer is influenced by the wake turbulence and the small-scale motion.
Computational Fluid Dynamic Prediction of Noise From a Cold Turbulent Propane Jet
Authors: Stanko Tanya S. , Ingham Derek B. , Fairweather Michael , Pourkashanian Mohamed
Published: August 2009

Numerical solutions of a turbulent jet flow are used to provide velocity information throughout a simple cold turbulent propane jet at a Reynolds number of 68,000. Predictions provided by the Reynolds-averaged Navier-Stokes simulations, based on a Reynolds stress turbulence model, are compared with experimental data available in the literature. The effect of the modelled inlet boundary conditions on the predicted flow field is described, and the discrepancy between the simulation results and experiment measurements is found to be less than the corresponding variations due to uncertainness in the experimental boundary conditions. In addition, these solutions are used as the basis for noise predictions for the jet based on Lighthill’s theory using the Goldstein broadband noise source formalization that postulates axisymmetric turbulence superposed on the mean flow. The latter model provides an aeroacoustic tool that is reasonable in identifying components or surfaces that generate significant amounts of noise, thereby providing opportunities for early design changes to aircraft and gas turbine components.
Rotordynamic Analysis of a Power Turbine Including Support Flexibility Effects
Authors: De Santiago Oscar , Abraham Edward
Published: August 2009

Power turbines are commonly used in the oil and gas industries as mechanical drives of process equipment such as centrifugal compressors or electrical generators. Power turbine rotordynamic design analysis is important because there may be interaction between the rotor and the structure, including the baseplate where they are mounted. This paper presents the results of the dynamic analysis of a power turbine considering the turbine frame, gas generator and baseplate. A large finite element model (FEM) of the assembly is used to generate transfer functions representing the dynamics of these components acting at the rotor bearing locations. The transfer function information is then used in a dedicated rotordynamic program to perform parametric studies and provide recommendations for the optimum power turbine bearing and baseplate configurations that meet all applicable industrial specifications. Predictions from a complete rotor-structure finite element model confirm the results from the dedicated rotordynamic program using transfer functions, showing that this simplified model can be used to satisfactorily study the system dynamics.
Blade-Shaft Coupled Resonance Vibration by Using Active Magnetic Bearing Excitation
Authors: Anegawa Norihisa , Fujiwara Hiroyuki , Matsushita Osami
Published: August 2009

The turbine generator requires sufficient reliability as a major component of the power plant. The rotor dynamics calculates the critical speed of the shaft-bearing system for design to avoid appearance of the critical speed, while the blade dynamics calculates the natural frequency of the blade to avoid nX resonance. For longer blades, however, the lower natural frequency requires that the design of the shaft and blade takes into account the coupling of the blade vibration mode with nodal diameter k = 0 and k = 1 with the vibration of the shaft. The present work analyzes the coupling of the parallel motion of the shaft with the in-plane vibration of the blade within k = 1 modes. More specifically, the existence of an unstable region due to coupling and the coupled resonance in an eight-blade (N = 8) where each blade is assumed to be a 1-DOF mass-spring system were analyzed in detail. Analysis was also made on the forced vibration of a stable damped system. At a rotational speed Ω = |ωs − ωb|, the vibration of the shaft was limited to a relatively small amplitude due to anti-resonance points resulting from the dynamic vibration absorber effect, while the resonance of the blades was relatively big amplitude. A violent coupled resonance resulting from the dynamic absorber effect of the blades and shaft was observed at a rotational speed Ω = ωs + ωb. The resonance in blade vibration at Ω = |ωb − ωs| was experimentally confirmed.
The Effects of Wet Compression on the Separated Flow in a Compressor Stage
Authors: Sun Lanxin , Li Yijin , Zheng Qun , Bhargava Rakesh
Published: August 2009

Effects of wet compression on the flow field within a compressor stage, particularly in presence of the separated flow region are not fully understood. Numerical simulations of 3D compressible separated flows within a wet compression compressor stage are carried out using a Computational Fluid Dynamics (CFD) program. Numerical computations of flow fields in a compressor cascade with wet compression assume that a separated region exist in the corner of the rotor blade suction surface and hub surface in the case of dry compression. Under different operating conditions and with wet compression, this study presents the changes in the extent of separated region on the flow channel surfaces, compression efficiency, pressure ratio and specific compression work etc. Also, effects of factors such as droplet size, droplet temperature, and injected water flow rate on the compressor stage performance and flow field within compressor stage passage have been investigated.
Numerical Simulation of a Transonic Centrifugal Compressor Blades Tip Clearance Flow of Vehicle Turbocharger
Authors: Guo Gongda , Zhang Yangjun , Xu Jianzhong , Zheng Xinqian , Zhuge Weilin
Published: August 2009

Flow induced by blade tip clearance is important for centrifugal compressor, especially for the high charging ratio transonic centrifugal compressor of the vehicle. Based on three-dimensional CFD method, the evolution and mechanism of tip clearance flow for the high charging ratio transonic centrifugal compressor are investigated. It is verified that shock waves have important effect on blade tip clearance flow. The original position and strength of leakage vortices depend on the position and intensity of shock waves. The tip leakage vortex (TLV) evolution is influenced by the evolution of passage vortex (PV), corner vortex (CV) and separated vortex (SV). Shock wave, adverse pressure gradient and casing boundary layer accelerate the leakage vortices breakdown. Leakage vortex loss is the most important factor of impeller loss. The research on the blades tip leakage flow of transonic centrifugal compressor for vehicle lays a foundation for transonic centrifugal compressor flow control.
Development of a Companion Set of Charts—Soft Sensor and Directional Moving Range—for Fault Monitoring, Detection and Diagnosis With Application to Gas Turbine Engines
Authors: Scheianu Dorin , Farrington Phillip A.
Published: August 2009

Gas turbines monitoring for fault detection and diagnosis is long desired to be embedded within control systems. Yet the general approach is to have alarms and shut downs when critical parameters exceed certain limits, and fault diagnosis is initiated on the behalf of experienced professionals and testing apparatus during scheduled maintenance time. Statistical methods for monitoring univariate and multivariate processes have been developed and publicized in the research literature. A gas turbine can be treated as a complex multivariate process with parameters depending both on control variables imposed by operator and on independent ambient parameters. The authors propose a set of companion charts that can be implemented on line and allows continuous monitoring both for fault amplitude — represented by a newly introduced soft sensor — and for process variability in the direction of interest. The control limits are introduced using multivariate statistical theory. The set of charts was applied at Wood Group LIT in a test cell, for monitoring process variability and for diagnosis and characterization of engine faults during tests. A second application is used for early detection of faults at the current serviced fleet of turbines.
Experimental and Numerical Investigation of a Centrifugal Compressor and Numerical Study of the Area Ratio and Tip Clearance Effects on the Performance Characteristic
Authors: Nili-Ahmadabadi Mahdi , Hajilouy-Benisi Ali , Durali Mohammad , Motavalli Sayyed Mostafa
Published: August 2009

In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and diffuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was studied numerically. The impeller area ratio was changed by cutting the impeller exit axial width from an initial value of 4.1 mm to a final value of 5.1 mm, resulting in an area ratio from 0.792 to 0.965. For the rotor with exit axial width of 4.6 mm, performance was investigated for tip clearance of 0.0, 0.5 and 1.0 mm. Results of this simulation at design point showed that the compressor pressure ratio peaked at an area ratio of 0.792 while the efficiency peaked at a higher value of area ratio of 0.878. Also the increment of the tip clearance from 0 to 1 mm resulted in 20 percent efficiency decrease.
Hot Streak and Vane Coolant Migration in a Downstream Rotor
Authors: Ong Jonathan , Miller Robert J.
Published: August 2009

This paper describes a method of improving the cooling of the hub region of high-pressure turbine (HPT) rotor by making better use of the unsteady coolant flows originating from the upstream vane. The study was performed computationally on an engine HPT stage with representative inlet hot streak and vane coolant conditions. An experimental validation study of hot streak migration was undertaken on two low-speed test facilities. The unsteady mechanisms that transport hot and cold fluid within the rotor hub region are first examined. It was found that vortex-blade interaction dominated the unsteady transport of hot and cold fluid in the rotor hub region. This resulted in the transport of hot fluid onto the rotor hub and pressure surface, causing a peak in the surface gas temperatures. The vane film coolant was found to have only a limited effect in cooling this region. A new cooling configuration was thus examined which exploits the unsteadiness in rotor hub to aid transport of coolant towards regions of high rotor surface temperatures. The new coolant was introduced from a slot upstream of the vane. This resulted in the feed of slot coolant at a different phase and location relative to the vane film coolant within the rotor. The slot coolant was entrained into the unsteady rotor secondary flows and transported towards the rotor hub-pressure surface region. The slot coolant reduced the peak time-averaged rotor temperatures by a similar amount as the vane film coolant despite having only a sixth of the coolant mass flow.
Some Effects of Non-Axisymmetric End Wall Profiling on Axial Flow Compressor Aerodynamics: Part II—Multi-Stage HPC CFD Study
Authors: Harvey N. W. , Offord T. P.
Published: August 2009

Non-axisymmetric end wall profiling is now a well established design methodology in axial flow turbines, used principally to improve their aerodynamic efficiency by reducing secondary loss. However, profiled end walls (PEWs) have yet to find an in-service application in a gas turbine compressor. This two-part paper presents the results of a number of studies, both experimental and computational, into the potential aerodynamic benefits of applying PEWs in axial flow compressors. The second paper describes an investigation into PEWs as a means of suppressing stator hub corner stall. An in-house design optimisation system (SOPHY) was applied to a typical embedded stator row in a multi-stage HP compressor. This enabled a new PEW geometry to be defined which is shown to be an effective alternative to 3-D aerofoil shaping in controlling stator hub corner stall. The results of this new study and of the work described in the first paper have been combined in a further investigation. PEWs were applied to an HPC with purely 2-D blading, which exhibited extensive stator hub corner stall at off-design conditions. CFD analysis showed that stator hub corner stall was successfully suppressed by the PEWs. It is concluded that PEWs can significantly affect the end wall flow field and have similar effects on corner stall as 3-D blading. The potential for improving the performance of axial flow compressors using PEWs is discussed. To successfully achieve any such improvements, extensive computational resources that are dedicated to design optimisation will be required.
Shaping of Tip End-Plate to Control Leakage Vortex Swirl in Axial Flow Fans
Authors: Corsini Alessandro , Rispoli Franco , Sheard A. G.
Published: August 2009

This paper reports on quantitative tests of passive techniques for rotor-tip noise control in low-speed axial flow fans, based on blade-tip modifications involving the addition of anti-vortex appendages as end-plates. The end-plate thickness chord-wise distribution is determined to control the chord-wise evolution of the leakage vortex rotation number. The results confirm that the new end-plate configurations provide a mechanism by which leakage vortex bursting can be avoided. As such, the modified rotors represent an effective means of passive control of vortex breakdown.
Test Results From the Advanced Humid Air Turbine System Pilot Plant: Part 1—Overall Performance
Authors: Higuchi Shinichi , Koganezawa Tomomi , Horiuchi Yasuhiro , Araki Hidefumi , Shibata Takanori , Marushima Shinya
Published: August 2009

The AHAT (advanced humid air turbine) system is based on a recuperated cycle using high-humidity air. This system improves thermal efficiency by using the high-humidity air as working gas. After many studies and elemental tests, a 4MW-class pilot plant was planned and built in order to verify feasibility of the AHAT system from the viewpoints of heat cycle characteristic and engineering. This plant consists of a gas turbine, a recuperator, a humidification tower, a water recovery system, an economizer, and other components. The gas turbine consists of a two-stage centrifugal compressor (pressure ratio of 8), a reverse-flow type single-can combustor, and a two-stage axial-flow turbine. In overall performance tests, the plant thermal efficiency exceeded 40%LHV.
Axial-Transverse Coupled Vibration Analysis of a Swinging Roller-Follower CAM Due to Flexible Follower Rod
Authors: Chang J. R. , Huang M. C.
Published: August 2009

In this paper, the equations of motion of a swinging roller-follower cam for rise-dwell-fall-dwell (RDFD) case are derived by applying Hamilton’s principle and the assumed mode method. The cycloidal displacement (sinusoidal acceleration) motion is used to describe the rise and the fall motions of the follower. The corresponding cam profile is determined using theory of envelopes. The follower rod is considered to be flexible and modeled as a Rayleigh beam including axial and transverse deflections. The roller rolls in the cam groove. The contact point between the cam and the roller is an unknown point though it is restrained in the cam groove. The contact point position depends not only on the rigid-body motions of the cam system but also the flexible vibrations of the follower rod. Two geometric constraints are formulated to restrict the roller motion and added to the Hamilton’s principle with Lagrange multipliers. The numerical integration method is applied to solve the non-linear differential-algebraic equations to obtain the vibration responses of the cam system. The numerical results for the studied cases show that the follower vibrates significantly especially for the case of high rotation speed of cam. The follower still vibrates during the dwell interval. The parameter effects including the cam rotation speed, the follower length and cross-sectional radius, and the total rise on the vibration behavior have been investigated.
Numerical Method for Turbomachinery Tonal Noise Generation and Radiation Simulation Using CAA Approach
Authors: Nyukhtikov Mikhail A. , Rossikhin Anton A. , Sgadlev Vasily V. , Brailko Igor A.
Published: August 2009

The numerical method for 3D calculation of the turbomachinery tonal noise generation, propagation and radiation in the near and far fields taking account of the rotor-stator interaction is developed in CIAM. The method is based on the direct numerical solution of three-dimensional Euler equations for disturbances in time or in frequency domain using numerical methods of computational acoustics (CAA). For far-field radiation calculation the Ffowcs Williams method is used. The method is build into CIAM domestic aeroacoustic solver 3DAS (3 Dimensional Acoustics Solver). In this paper we present some examples of our method applications for calculation of rotor-stator interaction and propagation: • Ducted fan tonal noise simulation; • Ducted counter-rotated fan noise simulation; • Low pressure turbine tonal noise simulation.
Characterization of Advanced Combustor Cooling Concepts Under Realistic Operating Conditions
Authors: Behrendt Thomas , Lengyel Timea , Hassa Christoph , Gerenda´s Miklo´s
Published: August 2009

For future low emission aero engine combustors a significant reduction of cooling air consumption is required. Quantitative data of the performance of advanced cooling concepts in a realistic environment in addition to existing data from scaled isothermal investigations is needed by combustor designers for further improvements. In this contribution the effect of the cooling air properties on the cooling effectiveness of different advanced cooling concepts at realistic operating conditions is presented and analyzed. Adapting of the measuring techniques and correction of the exhaust gas radiation will be especially addressed. An introduction into basic cooling design considerations is included in the article.
Experimental Evaluation of Abradable Seal Performance at High Temperature
Authors: Dadouche A. , Conlon M. J. , Dmochowski W. , Liko B. , Bedard J.-P.
Published: August 2009

Abradable seals have been used in aero-engines and land-based gas turbines for more than three decades. They are applied to various sections of the engine in order to reduce gas leakage by optimizing the gap between rotating and stationary parts. This optimization represents a significant increase in efficiency and decrease in fuel consumption. Performance evaluation of any abradable seal includes measurement of its mechanical properties, abradability tests and (ultimately) tests in engines. The aim of this paper is to study the effect of temperature on the rub performance of abradable seals. A series of experiments has been carried out in order to evaluate a commercially available seal material at different operating conditions. The effect of operating temperature on contact force, abrasion scar appearance and blade wear is examined and analyzed. A microstructural analysis of the rub scar has also been performed.
Development and Validation of a 1-D Tool for Thermoacoustic Instabilities Analysis in Gas Turbine Combustors
Authors: Andreini A. , Facchini B. , Mangani L. , Simonetti F.
Published: August 2009

In the last years, the more restrictive environmental legislations have constrained gas turbine manufacturers to the development of new low-emission combustors. Lean Premixed technology has become a necessary standard to meet emissions requirements and allowing an heavy reduction of nitrogen oxides emission. This kind of technology, due to the use of lean premixed mixtures, is severely affected by thermoacoustic phenomena which cause damages to combustor components and consequently reduce the overall gas turbine life of a factor of two or more. Specifically, premixed flames pose the threat of pressure oscillations. This phenomenon is the effect of the strong interaction between combustion heat-release and fluid dynamics aspects. In order to investigate thermoacoustic instabilities, a mono-dimensional code was developed and validated. It takes into account only longitudinal frequencies and it is thought to be highly modular to modify or add blocks, corresponding to different thermoacoustic models. The tool is based on a lumped-parameter approach, which consists in considering constant mean flow quantities over each fundamental straight duct element and a nodal point at each duct interface. For each interface, where an acoustic impedance could be present, the linearized fluctuating mass, momentum and energy equations are solved including entropic waves. To validate such tool, several tests, referring to actual test rigs and experimental gas turbine combustor geometries, were performed. The results show a general agreement with empirical data and other numerical results reported in literature in terms of resonance frequencies, stability and modal shapes, both for no flame and fluctuating heat release cases.
Knowledge Based Prognostics Models for Gas Turbine Core Components
Authors: Slottner Pontus , Wa¨rja Mathias
Published: August 2009

This paper presents a model that translates the gas turbine operation history into component load histories that can be used to calculate component based inspection intervals. It can be concluded that it is possible to develop accurate prognostics systems working on a component level. Such systems could predict maintenance requirements in a safe and sufficiently accurate way. There are many situations where theory and reality will not agree completely. By adding structured feedback to the prognostics process, the quality of prognostics, design and maintenance processes should improve. The quality of prognostics increases with the willingness to share data between maintenance provider and operator. It can be concluded that in an environment of information sharing between the involved parties, knowledge based prognostics should provide benefits to both maintenance provider and operator.
U.S. Navy Experience With SSS (Synchro-Self-Shifting) Clutches
Authors: Hendry Morgan L. , Zekas B. Michael
Published: August 2009

The U.S. Navy has nearly forty years of experience using SSS (Synchro-Self-Shifting) Clutches in main reduction gears of gas-turbine-driven ships and propulsion systems with combinations of gas turbines and diesel engines or electric motors, and in steam-turbine propulsion plants for use with electric motor drives. Over 900 SSS Clutches have been installed in fourteen different classes of U.S. Navy ships, some in service for over thirty years. This paper presents a brief overview of the principle SSS Clutch design features and the operating experience in naval propulsion systems worldwide, including operation in various propulsion plants such as controllable reversible pitch (CRP) propellers, fixed-pitch propellers (FPP), etc. The paper will also focus on SSS Clutch designs for specific U.S. Navy applications and installations, U.S. Navy experience, and design changes and improvements that have been implemented since the initial U.S. Navy use of SSS Clutches. Detailed metric (statistical) data, used by the U.S. Navy to evaluate equipment performance and life cycle costs, such as mean time between failure (MTBF), mean time to repair (MTTR), mean logistics delay time (MLDT), and operational availability (Ao) will be used to support experience. In-service experience and failure modes will also be explained as well as findings from the evaluation of clutches that have been subjected to extreme operation/incidents such as overspeed, overtorque, high shock blast, and flood damage. The final part of the paper will discuss current/future applications on U.S. Navy vessels such as the LHD-8, LCS and others; and how the design/features of those SSS Clutch designs will satisfy the operational, reliability, and maintainability requirements established for each ship platform. The metrics and lessons learned will be shown to be equally applicable to clutches for critical auxiliary drive applications such as naval gas turbine generator starting and naval steam turbine generator turning gear systems and how these metrics and lessons learned are being applied for current and future U.S. Navy ship systems.
Benchmarking Gas Path Diagnostic Methods: A Public Approach
Authors: Simon Donald L. , Bird Jeff , Davison Craig , Volponi Al , Iverson R. Eugene
Published: August 2009

Recent technology reviews have identified the need for objective assessments of engine health management (EHM) technology. The need is two-fold: technology developers require relevant data and problems to design and validate new algorithms and techniques while engine system integrators and operators need practical tools to direct development and then evaluate the effectiveness of proposed solutions. This paper presents a publicly available gas path diagnostic benchmark problem that has been developed by the Propulsion and Power Systems Panel of The Technical Cooperation Program (TTCP) to help address these needs. The problem is coded in Matlab™ and coupled with a non-linear turbofan engine simulation to produce “snap-shot” measurements, with relevant noise levels, as if collected from a fleet of engines over their lifetime of use. Each engine within the fleet will experience unique operating and deterioration profiles, and may encounter randomly occurring relevant gas path faults including sensor, actuator and component faults. The challenge to the EHM community is to develop gas path diagnostic algorithms to reliably perform fault detection and isolation. An example solution to the benchmark problem is provided along with associated evaluation metrics. A plan is presented to disseminate this benchmark problem to the engine health management technical community and invite technology solutions.
Laminar Flame Speed Measurements of H2/CO/CO2 Mixtures Up to 15 atm and 600 K Preheat Temperature
Authors: Natarajan J. , Kochar Y. , Lieuwen T. , Seitzman J.
Published: August 2009

Laminar flame speeds of lean H2/CO/CO2 (syngas) fuel mixtures have been measured for a range of H2 levels (20–90% of the fuel) at pressures and reactant preheat temperatures relevant to gas turbine combustors (up to 15 atm and 600 K). A conical flame stabilized on a contoured nozzle is used for the flame speed measurement, which is based on the reaction zone area calculated from chemiluminescence imaging of the flame. A O2:He mixture (1:9 by volume) is used as the oxidizer, rather than standard air, in order to suppress the hydrodynamic and thermo-diffusive instabilities that become prominent at elevated pressure conditions for lean H2/CO fuel mixtures. All the measurements are compared with numerical predictions based on two leading kinetic mechanisms: the H2/CO mechanism of Davis et al. and the C1 mechanism of Li et al. The results generally agree with the findings of an earlier study at atmospheric pressure: 1) for low H2 content (<40%) fuels, the model predictions are in good agreement with measurements at both 300 K and 600 K preheat temperature; but 2) the models tend to over predict the temperature dependence of the flame speed for medium (∼40–60%) and high (> 60%) H2 content fuels, especially at very lean conditions. The elevated pressure (∼15 atm) results, however, reveal that the effect is less pronounced than at atmospheric pressure. The exaggerated temperature dependence of the current models may be due to errors in the temperature dependence used for so-called “low temperature” reactions that become more important as the preheat temperature is increased. The radiation effects associated with CO2 addition to the fuel (up to 40%) is found to be less important for medium and high H2 content syngas fuels at elevated pressure and preheat temperature.
25,000-Hour Hybrid Oxide CMC Field Test Summary
Authors: Van Roode Mark , Price Jeff , Otsuka Joel , Szweda Andy , More Karren , Sun Jiangang
Published: August 2009

A Hybrid Oxide CMC Liner was evaluated in field testing of a Solar Turbines Incorporated Centaur® 50S engine for 25,404 hours and 109 starts between 2003 and 2006. The Hybrid Oxide CMC configuration consisted of a Nextel 720 aluminosilicate fiber/alumina matrix CMC and overlaying Friable Graded Insulation (FGI). The liner remained functional throughout the engine test. Borescoping during the first half of the field testing revealed little visual damage to the CMC liner, but erosion, affecting about 1–2 mm of the initial ∼ 5mm FGI thickness was noticed upon inspection of the liner after the midpoint of the field test. The erosion correlated with the hottest areas of the liner surface. Field testing was continued after minor liner repair. Damage to one area of the liner surface was observed in borescoping during the second half of the field test. Visual inspection after completion of the engine test indicated large areas of considerable CMC porosity/delamination within a few plies from the OD surface. Residual thickness measurements following the engine field testing indicated that of the original thickness, 2.0 – 2.6 mm of FGI had been lost. The surface recession is in the range expected based on a degradation model for alumina-based CMCs.