bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a Low Emission Gas Turbine Operated on Hydrogen
Authors: Therkelsen Peter , Mauzey Josh , McDonell Vince , Samuelsen Scott
Published: September 2008

The ever increasing strain on traditional centralized power generation and distribution systems has led to an increase in the use of distributed generation (DG) technologies. DG technologies are commonly found in urban areas that are sensitive to criteria pollutants, and as a result, they are subject to increasingly stringent emission regulations. Paralleling the growth of installed DG is the ever-increasing interest in hydrogen as an alternative fuel to natural gas. As a hydrogen infrastructure is developed, a desire to use this new fuel for DG applications will evolve. Microturbine generators (MTGs) are one example of DG technology that has emerged in this paradigm and are the technology of interest in the present work. To evaluate the potential role for hydrogen fired MTGs in this paradigm, understanding of what emission levels can be expected from such a system is needed The current study retrofits a natural gas fired MTG for operation on hydrogen and characterizes the resulting operability and emissions performance. The results of implementing design changes to improve emissions performance while maintaining stability and safety of the MTG when operating on hydrogen fuel are presented. The results also show improved stability limits which are utilized to help attain lower emissions of NOx. Further optimization is needed to achieve the NOx levels necessary to meet current regulations.
Important Parameters and Performance Testing of Evaporative Inlet Air Cooling System for Gas Turbines: A User’s Experience
Authors: Gajjar Hemant
Published: September 2008

Inlet Air Cooling of gas turbine engines for power augmentation has seen increasing application over the past decade. Evaporative inlet air cooling has been particularly preferred by the Gas Turbine operators due to its low cost and ease of installation. Two of the important considerations for a GT operator are the proper selection of the EIAC and, after installation, its proper testing to assure required performance. This paper is based on the experience, as a user, of selecting a inlet air cooling system and then implementing a Fogging type Evaporative Cooling system. It highlights the important parameters related to evaporative cooling system and in particular fogging, and how the site testing can be handled to ensure proper performance. Concepts of ‘Conversion Effectiveness’ and ‘Evaporation Effectiveness’ have also been introduced in this paper.
Biaxial Thermo Mechanical Fatigue Life Propety of a Ni Base DS Super Alloy
Authors: Ogata Takashi , Yamamoto Masato
Published: September 2008

Development of life assessment methods of high temperature components in gas turbine for maintenance and operating cost reduction is strongly demanded by Japanese utilities. Especially, first row blades are subjected to complicated. Thermo-Mechanical-Fatigue (TMF) loading during start-steady state-stop cycles. Therefore it is important to clarify the TMF life property of blade materials to develop a life assessment procedure. In this study, tension-torsion biaxial TMF tests have been performed between 450C and 870C on a Ni base directional solidified (DS) supper alloy. Strain ratio, φ was defined as shear strain range, Δγ, to normal strain range, Δε, and φ varied from 0 to infinite. The “Blade waveform” which simulated surface temperature and strain loading condition of the blade, was employed. The biaxial TMF tests were also carried out on coated specimens with CoCrAlY. Fatigue life under biaxial TMF loading showed strain ratio dependency giving shorter life with increasing φ. Considering biaxial stress effect on failure life, an equivalent shear strain range was derived based on Γ -plane theory, and biaxial TMF life was well correlated with the equivalent shear strain range. The biaxial TMF life was reduced by introducing strain hold duration at the maximum temperature. The maximum stress increased by introducing the hold time due to increasing mean stress level in the Blade waveform. It was concluded that creep damage gradually accumulated during cycles resulting in TMF life reduction. The nonlinear creep-fatigue damage accumulation model was applied to predict failure life of the hold time tests. As a result, failure life could be predicted within factor of 1.5 on observed life. It was found that fatigue life of CoCrAlY coated material reduced 1/2 to 1/3 from that of without coated material. From observation of longitudinal section of the coated specimens, many cracks started from coating surface and penetrated into the substrate. It was concluded that CoCrAlY coating reduced the biaxial TMF life due to acceleration of crack initiation period in the substrate.
Fleet and Usage Management System (FUMSTM) Technologies for Gas Turbines
Authors: Azzam Hesham , Knight Peter , Ellison Roger , Bryant Ken , Cook Jonathan , Driver Stuart
Published: September 2008

Working closely with the UK Ministry of Defence (MOD), Smiths has developed a Fleet and Usage Management System (FUMS™) to enable proactive fleet management and continuous diagnostic/prognostic improvements through a single fusion and decision support platform for helicopters, aeroplanes and engines. This paper gives an overview of a suite of FUMS™ algorithms that have been successfully developed for gas turbine applications and validated using a large volume of engine data. The system has been used to analyse both airborne acquired data and ground test-bed data. The system algorithms have been targeted at evaluating the following: stresses of compressor components, thermal transient stresses of turbine components, fatigue. Total Accumulated Cycles (TAC), engine vibration, neural network based performance/degradation and, Usage Indices (UIs) that summarise engine parameters and at the same time indicate the life/condition of engine components. By operating on data from the same engine on two test-beds, the system can be used to normalise the engine vibration and reconcile any differences in vibration-based acceptance/rejection criteria: these differences can result in the acceptance of an engine for on-wing operation at one site and the rejection of the engine at another site. The paper also gives an overview of the FUMS™ intelligent management software, which has allowed the MOD to plug-in 3rd party applications. In this way, MOD can evaluate, verify and procure engine technologies developed by various suppliers and build engine applications from these technologies without the need for software re-writing.
Implementation of a System for the Analysis and Evaluation of Advantages of Distributed Generation
Authors: Proietti Stefania , Arcioni Livia , Desideri Umberto
Published: September 2008

This paper presents a research activity at the Industrial Engineering Department of the University of Perugia, Italy, aimed at the development of a software tool (Co.Gis®) based on the use of interactive vectorial maps which allows to help the design and selection of a distributed generation system. The software is aimed at helping the user in the selection of the main characteristics of distributed generation systems by means of a methodology that calculates the avoided losses on the electrical grid and many other economical and technical indicators. The software can also be used to quantify the environmental benefits, to help in the feasibility studies of distributed generation systems and to manage the data and to control groups of small generation systems (Virtual Power Plant). The geo-referenced database of the present co-generation systems has been constructed on the Italian territory, with 1606 installations and approximately 12.000 MWe installed electric power. A complete database, which also includes all the other non-cogenerative distributed generation systems installed on the territory of Umbria, a small region in center of Italy, was prepared. This database is a powerful tool to characterize immediately the type of users that use cogeneration plants, to know the requirements of the market and to characterize and propose innovative energy conversion systems. Another characteristic is the possibility to perform feasibility studies of cogeneration systems. This instrument allows a significant simplification of the technical-economic evaluation procedures for the installation of an industrial or civil cogeneration system. The feasibility study can be combined with the calculation of electrical losses on the electricity transmission grid. The calculation of the avoided electrical losses, in terms of avoided CO2, offers a valid instrument to evaluate the environmental impact of different electrical generation systems and shows the advantages offered by distributed generation in the traditional generation park in Italy.
The Influence of Including a Partially Smooth Section in the 2nd Leg of an Internally Ribbed Two Pass Cooling Channel
Authors: Pape Detlef , Jenkins Sean , von Wolfersdorf Jens , Weigand Bernhard , Schnieder Martin
Published: September 2008

Internal cooling schemes for blades in a gas turbine engine often are subject to compromises between increased pressure losses in return for greater levels of heat transfer required to maintain durability levels in the engine’s harsh environment. Rib configurations have been the subject of much study in past years, however these configurations are normally presumed to be used in “full-coverage” mode, meaning that the ribs are placed in the channel in a continuous and uniform manner. This study investigates the interaction between the bend effects downstream of a 180° bend, which cause higher local heat transfer, and the effect of ribs. Some of the ribs directly downstream of the 180° bend in the 2nd leg of a two pass high aspect ratio (4:1) channel were removed and the effect on heat transfer was assessed. Experimental results showed that the heat transfer level recovered quickly once ribs were encountered. As expected, some decrease in heat transfer was observed in the region where ribs were removed; however total pressure losses in the channel were also much lower. Results include detailed two-dimensional heat transfer distributions determined by the transient liquid crystal method as well as an analysis of the balance between pressure recovery and local heat transfer levels. Generally, for the accuracy of the transient liquid crystal technique in complex three-dimensional flows, strongly varying fluid temperatures present in and downstream of the bend region must be taken into account. For this study, time and position dependent fluid temperature distributions were measured to account for these effects, making it possible to obtain high quality heat transfer results in those regions.
Boundary Layer Separation Control on a Flat Plate With Adverse Pressure Gradients Using Vortex Generators
Authors: Canepa Edward , Lengani Davide , Satta Francesca , Spano Ennio , Ubaldi Marina , Zunino Pietro
Published: September 2008

The continuous tendency in modern aeroengine gas turbines towards reduction of blade count and ducts length may lead to aerodynamic loading increase beyond the limit of boundary layer separation. For this reason boundary layer separation control methods, up to now mostly employed in external aerodynamics, begin to be experimented in internal flows applications. The present paper reports the results of a detailed experimental study on low profile vortex generators used to control boundary layer separation on a large-scale flat plate with prescribed adverse pressure gradients. Inlet turbulent boundary layer conditions and pressure gradients are representative of aggressive turbine intermediate ducts. This activity is part of a joint European research program on Aggressive Intermediate Duct Aerodynamics (AIDA). The pressure gradients on the flat plate are generated by increasing the aperture angle of a movable wall opposite to the flat plate. To avoid separation on the movable wall, boundary layer suction is applied on it. Complementary measurements (surface static pressure distributions, surface flow visualizations by means of wall mounted tufts, instantaneous and time-averaged velocity fields in the meridional and cross-stream planes by means of Particle Image Velocimetry) have been used to survey the flow with and without vortex generators. Three different pressure gradients, which induce turbulent separation in absence of boundary layer control, were tested. Vortex generators height and location effects on separation reduction and pressure recovery increase were investigated. For the most effective VGs configurations detailed analyses of the flow field were performed, that demonstrate the effectiveness of this passive control device to control separation in diffusing ducts. Particle Image Velocimetry vector and vorticity plots illustrate the mechanisms by which the vortex generators transfer momentum towards the surface, re-energizing the near-wall flow and preserving the boundary layer from separation.
An Overview of Turbine and Combustor Development for Coal-Based Oxy-Syngas Systems
Authors: Pronske Keith , Trowsdale Larry , Macadam Scott , Viteri Fermin , Bevc Frank , Horazak Dennis
Published: September 2008

Coal combustion technology is required that is capable of: (1) co-producing electricity and hydrogen from coal while; (2) achieving high efficiency, low capital cost, low operating cost, and near-zero atmospheric emissions; and (3) producing a sequestration-ready carbon dioxide stream. Clean Energy Systems, Inc. (CES) and Siemens Power Generation, Inc., are developing this technology that would lead to a 300 to 600 MW, design for a zero emissions coal syngas plant, targeted for the year 2015, CES and Siemens received awards on September 30, 2005 from the U.S. Department of Energy’s; Office of Fossil Energy Turbine Technology R&D Program. These awards are designed to advance turbines and turbine subsystems for integrated gasification combined cycle (IGCC) power plants. Studies have shown [1–4] that replacing air with nearly pure oxygen and steam in a turbine’s combustion chamber is a promising approach to designing coal based power plants with high efficiency and near-zero emissions. Siemens will combine current steam and gas turbine technologies to design an optimized turbine that uses oxygen with coal derived hydrogen fuels in the combustion process under a DOE Turbine Development Project [5]. CES will develop and demonstrate a new combustor technology powered by coal syngas and oxygen under a DOE Combustor Development Project [6]. The proposed programs build upon twelve years of prior technical work and government-sponsored research to develop and demonstrate zero-emission fossil fuel power generation. The planned system studies build upon previous work conducted by private, public, and foreign organizations, including CES [7–9], DOE’s National Energy Technology Laboratory (NETL) [10–12], Air Liquide (AL) [1,13], Lawrence Livermore National Laboratory (LLNL) [2], Fern Engineering, Inc. [14], and Japanese investigators [15, 16]. Other pertinent data related to coal gasification, advanced air separation unit (ASU), plant integration and plant systems optimization, etc., can be found in references [17–23].
Ceramic Matrix Composite Vane Subelement Burst Testing
Authors: Brewer David N. , Verrilli Michael , Calomino Anthony
Published: September 2008

Burst tests were performed on Ceramic Matrix Composite (CMC) vane specimens, manufactured by two vendors, under the Ultra Efficient Engine Technology (UEET) project. Burst specimens were machined from the ends of 76mm long vane sub-elements blanks and from High Pressure Burner Rig (HPBR) tested specimens. The results of burst tests will be used to compare virgin specimens with specimens that have had an Environmental Barrier Coating (EBC) applied, both HPBR tested and untested, as well as a comparison between vendors.
Experimental Study of the Thermal Development in a Rotating Square-Ended U-Bend
Authors: Iacovides Hector , Kounadis Diamantis , Launder Brian E. , Xu Zeyuan
Published: September 2008

This paper reports an experimental study of the thermal development in an idealized model of a blade cooling passage of smooth inner surfaces, comprising a square-ended U-bend with a cross-section that changes from a square upstream to a 2:1 rectangle downstream of the turn. The two flat walls are heated electrically, while the outer wall and the splitter plate are thermally insulated. The steady state liquid crystal technique is used to map the local Nusselt number variation. Measurements are obtained using a stationary air flow facility and also a rotating water flow facility. This enables us to investigate the effects on the thermal development of Reynolds variation from 30,000 to 100,000, Prandtl numbers of 0.7 and 5.8, and rotation numbers, from 0 to 0.4. The effects of minor modifications in the cross-sectional area at the bend exit, on the thermal development, under both stationary and rotating conditions, are also explored.
Improving Film Cooling Performance Using Airfoil Contouring
Authors: Kohli Atul , Bogard David G.
Published: September 2008

In this study, a CFD-based optimization process is used to change the contour of the airfoil near a suction side cooling hole in order to improve its film effectiveness characteristics. An overview of the optimization process, which includes automated geometry, grid generation and CFD analyses is provided. From the results for the optimized geometry it is clear that the detachment of the cooling jet is much reduced and the cooling jet spread in the spanwise direction is increased substantially. The new external contour was then tested in a low-speed wind tunnel to provide a direct measure of the predictive capability. Comparisons to verification test data indicate that good agreement was achieved for both pressure and film cooling effectiveness behavior. This study proves that despite its limitations, current RANS methodology can be used a viable design tool and lead to innovative concepts for improving film cooling effectiveness.
A Method for Estimating the Influence of Time-Dependent Vane and Blade Pressure Fields on Turbine Rim Seal Ingestion
Authors: Johnson Bruce V. , Jakoby Ralf , Bohn Dieter E. , Cunat Didier
Published: September 2008

A method of estimating the turbine rim seal ingestion rates was developed using the time-dependent pressure distributions on the hub of turbines and a simple orifice model. Previous methods use the time-averaged pressure distribution downstream of the vanes to estimate seal ingestion. The present model uses the pressure distribution near the turbine hub, obtained from 2-D time-dependent stage calculations, and a simple-orifice model to estimate the pressure-driven ingress of gas path fluid into the turbine disk cavity and the egress of cavity fluid to the gas path. The time-dependent pressure distribution provides the influence of both the vane wakes and the bow wave from the blade on the pressure difference between hub pressure at an azimuthal location and the cavity pressure. Results from the simple-orifice model are used to determine the effective Cd that matches the cooling effectiveness at radii near the rim seal with the amount of gas-path-ingested flow required to mix with the coolant flow. Cavity ingestion data from rim-seal-ingestion experiments in a 1.5-stage turbine and numerical simulations for a 1-vane-2-blade sector of the 16 vane, 32 blade turbine were used to evaluate the method. The experiments and simulations were performed for close-spaced and wide-spaced half stages between both the vane and blade and between the blade and a trailing teardrop-shaped strut. The comparison of the model with a single Cd for axial gap seals and the experiments showed reasonable agreement for both close- and wide-spaced stages.
Comparison of Four Different Two-Equation Models of Turbulence in Predicting Film Cooling Performance
Authors: Hassan Jawad S. , Yavuzkurt Savas
Published: September 2008

The capabilities of four two-equation turbulence models in predicting film cooling effectiveness were investigated and their limitations as well as relative performance are presented. The four turbulence models are the standard, RNG, and realizable k-ε models as well as the standard k-ω model all found in the FLUENT CFD code. In all four models, the enhanced wall treatment has been used to resolve the flow near solid boundaries. A systematic approach has been followed in the computational setup to insure grid-independence and accurate solution that reflects the true capabilities of the turbulence models. Exact geometrical and flow-field replicas of an experimental study on discrete-jet film cooling were generated and used in FLUENT. A pitch-to-diameter ratio of 3.04, injection length-to-diameter ratio of 4.6 and density ratios of 0.92 and 0.97 were some of the parameters used in the film cooling analysis. Furthermore, the study covered two levels of blowing ratio (M = 0.5 and 1.5) at an environment of low free-stream turbulence intensity (Tu = 0.1%). The standard k-ε model had the most consistent performance among all considered turbulence models and the best centerline film cooling effectiveness predictions with the results deviating from experimental data by only ±10% and about 20–60% for the low (M = 0.5) and high (M = 1.5) blowing ratio cases, respectively. However, centerline side-view and surface top-view contours of non-dimensional temperature for the standard k-ε cases revealed that the good results for film cooling effectiveness η compared to the experimental data were due to a combination of an over-prediction of jet penetration in the normal direction with an under-prediction of jet spread in the lateral direction. The standard k-ω model completely failed to produce any results that were meaningful with under-predictions of η that ranged between 80 and 85% for the low blowing ratio case and over-predictions of about 200% for the high blowing ratio case. Even though the RNG and realizable models showed to have better predicted the jet spread in the lateral direction compared to the standard k-ε model, there were some aspects of the flow, such as levels of turbulence generated by cross-flow and jet interaction, that were not realistic resulting in errors in the η prediction that ranged from −10% to +80% for the M = 0.5 case and from −80% to +70% for the M = 1.5 case. As a result of this study at this point it was concluded that the standard k-ε model have the most promising potential among the two-equation models considered. It was chosen as the best candidate for further improvement for the simulation of film cooling flows.
Development of a 2-D Compressor Streamline Curvature Code
Authors: Templalexis Ioannis , Pilidis Pericles , Pachidis Vassilios , Kotsiopoulos Petros
Published: September 2008

Two-dimensional compressor flow simulation software has always been a very valuable tool in compressor preliminary design studies, as well as in compressor performance assessment, operating under uniform and non-uniform inlet conditions. In this context, a new streamline curvature (SLC) software has been developed capable of analyzing the flow inside a compressor in two dimensions. The software was developed to provide great flexibility, in the sense that it can be used as: a) A performance prediction tool for compressors of a known design, b) A development tool to assess the changes in performance of a known compressor after implementing small geometry changes, c) A design tool to verify and refine the outcome of a preliminary compressor design analysis, d) A teaching tool to provide the student with an insight of the two-dimensional flow field inside a compressor and how this could be effectively predicted using the SLC method, combined with various algorithms and loss models, e) A 2-D compressor model that can be integrated into a conventional 0-D gas turbine engine cycle simulation code for the investigation of the influence of non-uniform radial pressure profiles on whole engine performance. Apart from describing in detail the design, structure and execution of the SLC software, this paper also stresses the importance of developing robust, well thought-out software and highlights the main areas a potential programmer should focus on in order to achieve this. This manuscript highlights briefly the programming features incorporated into the development of software before continuing to explain the internal workings of individual algorithms. The paper reviews in detail the set of equations used for the prediction of the meridional flow field. Numerical aspects of the application procedure of the full radial equilibrium equation are examined. The loss models incorporated for subsonic and supersonic flow are presented for design and off design operating conditions. Deviation angle rules are presented, together with the parameters for quantifying the diffusion process. Moreover, the methods used for the prediction of surge and choke are discussed in detail. Finally, the end wall boundary layer displacement thickness calculation is discussed briefly, in conjunction with the blockage factor computation. The code has been validated against experimental results which are presented in this paper together with the strong and weak points of this first version of the software and the potential for future development.
Passive Damper LP Tests for Controlling Combustion Instability
Authors: Macquisten M. A. , Holt A. , Whiteman M. , Moran A. J. , Rupp J.
Published: September 2008

The drive to low emissions from GT combustors has pushed manufacturers towards leaner combustion systems. Lean combustion systems are susceptible to thermo acoustic or combustion instabilities, which can significantly limit the operation of the GT in terms of performance and emissions. Combustion instability is the result of coupling between fluctuations in the heat release rate and pressure waves. The occurrence of instability dependent on (a) satisfying the Rayleigh criterion and (b) the growth must exceed the losses of acoustic energy. The growth of instability can be controlled by increasing the level of acoustic damping via a Helmholtz resonator and through viscous damping. Design rules for a passive damper have been developed through the EU funded project called PRECCINSTA (Prediction and control of combustion instabilities in tubular and annular combustion systems) by the University of Cambridge. These design rules are for a doubled-skinned perforated liner where a biasing flow is used to dissipated sound energy. The sound dissipation mechanism is via vortex formation. These design rules were then validated against atmospheric and intermediate pressure combustion tests at Rolls-Royce for self-excited and forced excited oscillations. This paper summaries these tests and gives the results for a simple perforated liner as a passive acoustic damper.
Phase Resolved Laser Diagnostic Measurements of a Downscaled, Fuel Staged Gas Turbine Combustor at Elevated Pressure and Comparison With LES Predictions
Authors: Geigle Klaus Peter , Meier Wolfgang , Aigner Manfred , Willert Chris , Jarius Marc , Schmitt Patrick , Schuermans Bruno
Published: September 2008

A technical gas turbine combustor has been studied in detail with optical diagnostics for validation of Large-Eddy Simulations (LES). OH* chemiluminescence, OH laser-induced fluorescence (LIF) and particle image velocimetry (PIV) have been applied to stable and pulsating flames up to 8 bar. The combination of all results yielded a good insight into the combustion process with this type of burner and forms a data base which was used for the validation of complex numerical combustion simulations. Large-Eddy Simulations (LES) including radiation, convective cooling and air cooling were combined with a reduced chemical scheme that predicts NOx emissions. Good agreement of the calculated flame position and shape with experimental data was found.
Probabilistic Thermal Analysis of Gas Turbine Internal Hardware
Authors: Stearns Ethan , Cloud Dave , Filburn Tom
Published: September 2008

This paper documents the initial development of a method to perform probabilistic thermal analyses of gas turbine internal hardware and uses the turbine interstage seal of a turbofan engine as an example. The purpose of this analysis is to investigate the variability in steady state metal temperature due to variability in the secondary flow system. In addition to quantifying the variability in metal temperature, the sensitivity of the temperature to individual input variables is determined. As a prerequisite for a probabilistic thermal analysis, a probabilistic flow analysis was executed, with variability in engine performance and hardware geometry yielding variability in mass flow rates, heat generation and local swirl velocity. These outputs were used as stochastic inputs for the probabilistic thermal analysis. The analysis was run with correlated input as well as independently varying inputs. The results of this analysis showed that the metal temperature at the tip of the seal was sensitive and highly correlated to air source temperature, as expected. The mass flow rate of air across the seal and heat transfer coefficient also affected the metal temperature. By using correlated input variability, it is shown that variability in metal temperature is ultimately caused by variability in labyrinth seal clearance.
Experience With GSP as a Gas Path Analysis Tool
Authors: Visser W. P. J. , Pieters H. , Oostveen M. , van Dorp E.
Published: September 2008

SKF’s primary tool for gas turbine engine performance analysis is GSP (Gas turbine Simulation Program), a component based modeling environment that is developed at National Aerospace Laboratory NLR and Delft University of Technology, The Netherlands. One of the applications is gas path analysis (GPA) using GSP’s generic adaptive modeling capability. With GSP, gas path analysis has been applied to different aero engines at several maintenance facilities. Additional functionalities have been developed to analyze multiple engine operating points and combine results of different adaptive modeling configurations automatically, resulting in more accurate and reliable GPA results. A ‘multi-point calibration’ method for the reference model was developed providing a significant improvement of GPA accuracy and stability. Also, a method was developed using ‘multiple analysis cycles’ on different condition indicator subsets, which successfully generated values for all condition parameters in cases with fewer measurement parameters than condition indicators and where measurement data are unreliable. The method has been successfully demonstrated on the GEM42 turbo shaft engine. A number of case studies have shown GPA results corresponding to available maintenance notes and inspection data. The extension of the GSP GPA tool with a database system provides a useful tool for analyzing engine history and comparison of analyzed component conditions throughout the fleet. When a large amount of analysis data is stored in the database, statistic analyses, trending and data mining can be performed. Also maintenance work scope effect on engine performance can be predicted. In this paper, the newly developed GSP gas path analysis functionalities are described and experiences and results with the GEM42 engine operational environment are presented.
Heavy Duty Gas Turbine Simulation: Global Performances Estimation and Secondary Air System Modifications
Authors: Carcasci Carlo , Facchini Bruno , Gori Stefano , Bozzi Luca , Traverso Stefano
Published: September 2008

This paper reviews a modular-structured program ESMS (Energy System Modular Simulation) for the simulation of air-cooled gas turbines cycles, including the calculation of the secondary air system. The program has been tested for the Ansaldo Energia gas turbine V94.3A, which is one of the more advanced models in the family Vx4.3A with a rated power of 270 MW. V94.3A cooling system has been modeled with SASAC (Secondary Air System Ansaldo Code), the Ansaldo code used to predict the structure of the flow through the internal air system. The objective of the work was to investigate the tuning of the analytical program on the basis of the data from design and performance codes in use at Ansaldo Energy Gas Turbine Department. The results, both at base load over different ambient conditions and in critical off-design operating points (full-speed-no-load and minimum-load), have been compared with APC (Ansaldo Performance Code) and confirmed by field data. The coupled analysis of cycle and cooling network shows interesting evaluations for components life estimation and reliability during off-design operating conditions.
Thermo Acoustic Flame Transfer Function Prediction for Turbulent Non-Premixed Syngas Flames
Authors: Pater Sjoerd G. M. , Kok Jim B. W. , van der Meer Theo. H.
Published: September 2008

The thermo-acoustic behaviour of non-premixed turbulent syngas flames is investigated by means of transient RaNS Computational Fluid Dynamics simulations. Three cases with two different fuel compositions are considered. Both fuels are combusted in a turbulent non-premixed swirl stabilised mode, and are mixtures of hydrogen, carbon monoxide and nitrogen. One fuel contains methane in addition. The flame transfer function considered here, describes the relation between a perturbation of the fuel mass flow rate and the rate of heat release in the flame. The fuel mass flow is perturbed by an impulse excitation. The investigated geometry is a laboratory scale burner that is designed in the framework of the European Union sponsored HEGSA project. Experimental data are generated in tests at DLR (chemiluminescence and LIF). The CFD results show that methane addition to syngas has a significant influence on the flame transfer function. The addition of methane to syngas induces thermoacoustic damping for higher frequency (¿400 Hz) regions and increases amplification for low frequencies (¡200 Hz). The time delay of the transfer function is affected by the addition of methane due to both calorific value and chemical time scale effects. A decrease in inlet temperature also affects the flame transfer function. This is due to the slower chemistry and lower velocity.
Thermoeconomic Analysis of a Small-Size Biomass Gasification Plant for Combined Heat and Distributed Power Generation
Authors: Porta Matteo , Traverso Alberto , Marigo Luca
Published: September 2008

This paper presents the analysis of the thermoeconomic performance of an integrated atmospheric biomass gasifier internal combustion engine and microturbine cycle for heat and distributed power generation. The gasifier technology considered is based on the atmospheric updraft fixed-bed configuration: the gasifier performance was predicted at on-design with a 1-D model, which was previously verified with experimental measurements. The economic situation considered is the Italian scenario, updated to September 2005. In this scenario the electricity from renewables, such as biomass, and heat for domestic heating are awarded the so-called “green certificates”, which provide an additional income for the thermal plant for the first eight years of operation. The results show that the reference case of 600kWe is too small for actual commercial operation, and is of interest only for demonstration purposes. Instead, sizes over 2MWe are economically sustainable, although their sustainability strongly depends on the district-heating operating hours and the local cost of biomass. Detailed analysis and boundary values are provided.
Heat Transfer Measurements and Predictions for a Modern, High-Pressure, Transonic Turbine, Including Endwalls
Authors: Tallman James A. , Haldeman Charles W. , Dunn Michael G. , Tolpadi Anil K. , Bergholz Robert F.
Published: September 2008

This paper presents both measurements and predictions of the hot-gas-side heat transfer to a modern, one and 1/2 stage high-pressure, transonic turbine. Comparisons of the predicted and measured heat transfer are presented for each airfoil at three locations, as well as on the various endwalls and rotor tip. The measurements were performed using the Ohio State University Gas Turbine Laboratory Test Facility (TTF). The research program utilized an uncooled turbine stage at a range of operating conditions representative of the engine: in terms of corrected speed, flow function, stage pressure ratio, and gas-to-metal temperature ratio. All three airfoils were heavily instrumented for both pressure and heat transfer measurements at multiple locations. A 3-D, compressible, Reynolds-averaged Navier-Stokes CFD solver with k-ω turbulence modeling was used for the CFD predictions. The entire, 1-1/2 stage turbine was solved using a single computation, at two different Reynolds numbers. The CFD solutions were steady, with tangentially mass-averaged inlet/exit boundary condition profiles exchanged between adjacent airfoil-rows. Overall, the CFD heat transfer predictions compared very favorably with both the global operation of the turbine and with the local measurements of heat transfer. A discussion of the features of the turbine heat transfer distributions, and their association with the corresponding flow-physics, has been included.
Construction and Performance Evaluation of Prototype Atmospheric Pressure Turbine (APT)
Authors: Inoue K. , Harada E. , Kitajima J. , Tanaka K.
Published: September 2008

This research seeks to propose an atmospheric pressure turbine (ATP), based on the Inverted Brayton Cycle, which puts new, distributed power generation technology to practical use by using various gases at normal pressures and high temperature, from industrial furnaces, waste gasification furnaces, gas turbines, and fuel cells which work at high temperatures, (ex. MCFC: Molten Carbonate Fuel Cell, SOFC: Solid Oxide Fuel Cell) and attempts to save energy and reduce CO2. However, no research has been presented about the operation of a real APT. This paper describes a review of the effectiveness of APT, and shows an outline for the results of a trial run, as well as the production of an APT prototype. The simulation results using a process simulator “HYSYS” show that a 30 kW system has a generator end efficiency (LHV) of about 32%, which is comparable to the performance of other equipment of a similar power rating, such as micro gas turbines. Based on this simulation result we build a 3–5 kW APT prototype and operate. The result of this operation clarifies the basic characteristics of an APT including a performance of 8.7% thermal efficiency. An APT has a smaller specific power than a gas turbine. Accordingly, since its mechanical and dissipative heat losses are larger by comparison, it is important to reduce these losses to attain higher efficiency. Our APT was operated stably and the possibility can be used as a new system for distributed power generation using waste heat was confirmed.
A New Approach to Optimization of Cogeneration Systems Using Genetic Algorithm
Authors: Zomorodian Roozbeh , Khaledi Hiwa , Ghofrani Mohammad Bagher
Published: September 2008

Application of Cogeneration systems based gas turbine for heat and power production is increasing. Because of finite natural energy resources and increasing energy demand the cost effective design of energy systems is essential. CGAM problem as a cogeneration system is considered here for analyzing. Two new approaches are considered, first in thermodynamic model of gas turbine and cogeneration system considering blade cooling of gas turbine and second using genetic algorithm for optimization. The problem has been optimized from thermodynamic and Thermoeconomic view point. Results show that Turbine Inlet Temperature (TIT) in thermodynamic optimum condition is higher than thermoeconomic one, while blade cooling technology must be better for optimum thermodynamic condition. Heat recovery of recuperator is lower in thermoeconomic case; also, stack temperature is higher relative to thermodynamic case. The sensitivity of the optimal solution to the decision variables is studied. It has been shown that while for both thermodynamic and thermoeconomic optimum condition, pressure ratio, blade cooling technology factor and pinch-point temperature difference (only for thermoeconomic case) has the lowest effect, turbomachinary efficiencies (epically compressor polytropic efficiency) have the major effect on performance of cycle. Finally; a new product known as Mercury 50 gas turbine is studied for a cogeneration system and it has been optimized thermoeconomicly. Results show good agreement with manufacturer data.
Rotating Seal Rig Experiments: Test Results and Analysis Modeling
Authors: Paolillo Roger , Wang Cheng-Zhang , Vashist T. K. , Cloud David , Bingen Fons M. G. , Kool Gerrit A.
Published: September 2008

Current and future gas turbine engines are subject to increasing performance requirements and improved fuel efficiencies. The resultant engine cycles increase core flow temperatures requiring additional cooling flow while requiring a reduction in parasitic leakage by 25%–50% to meet the performance goals. The achievement of the reduced leakage requires that seal design concepts be tested and improvements validated in engine like conditions before they are introduced into the gas turbine product. This paper describes the process of how a potentially low leakage seal design was evaluated and tested in an advanced seal test rig facility. How existing engine seal leakage rig data was used to validate physics based models (CFD) of baseline labyrinth seal configurations, then used to run back to back sensitivity studies to identify seal design characteristics that could provide low leakage seal designs. The paper discusses the use of an Advanced Seal Rig (ASR) facility to test seal design concepts for gas turbine engine applications. Test seal flow results are presented and compared to the base line seal tests. The differences between the new seal design flow test results and the base line seal flow test results are investigated. Further, seal test flow results are compared with the validated physics based model predictions (CFD) run at the advanced seal rig test conditions. Differences between rig data and analysis are discussed. Future seal testing and analysis work is suggested.
Aerodynamic and Heat Flux Measurements in a Single Stage Fully Cooled Turbine: Part I — Experimental Approach
Authors: Haldeman C. W. , Mathison R. M. , Dunn M. G. , Southworth S. , Harral J. W. , Heitland G.
Published: September 2008

This paper describes the experimental approach utilized to perform experiments using a fully cooled rotating turbine stage to obtain film effectiveness measurements. Significant changes to the previous experimental apparatus were implemented to meet the experimental objectives. The modifications include the development of a synchronized blowdown facility to provide cooling gas to the turbine stage, installation of a heat exchanger capable of generating a uniform or patterned inlet temperature profile, novel utilization of temperature and pressure instrumentation, and development of robust double-sided heat flux gauges. With these modifications, time-averaged and time-accurate measurements of temperature, pressure, surface heat flux, and film effectiveness can be made over a wide range of operational parameters duplicating the non-dimensional parameters necessary to simulate engine conditions. Data from low Reynolds number experiments are presented to demonstrate that all appropriate scaling parameters can be satisfied and that the new components have operated correctly. Along with airfoil surface heat transfer and pressure data, temperature and pressure data from inside the coolant plenums of the vane and rotating blade airfoils are presented. Pressure measurements obtained inside the vane and blade plenum chambers illustrate passing of the wakes and shocks as a result of vane/blade interaction. Part II of this paper presents data from the low Reynolds number cooling experiments and compares these measurements to CFD predictions generated using the Numeca FINE/Turbo package at multiple spans on the vanes and blades.
Aerodynamic and Heat Flux Measurements in a Single Stage Fully Cooled Turbine: Part II — Experimental Results
Authors: Haldeman C. W. , Mathison R. M. , Dunn M. G. , Southworth S. , Harral J. W. , Heitland G.
Published: September 2008

This paper presents measurements and the companion CFD predictions for a fully cooled, high-work single stage HP turbine operating in a short-duration blowdown rig. Part I of this paper presented the experimental approach, and Part II focuses on the results of the measurements and demonstrates how these results compare to predictions made using the Numeca FINE/Turbo CFD package. The measurements are presented in both time-averaged and time-accurate formats. The results include the heat transfer at multiple spans on the vane, blade, and rotor shroud as well as flow path measurements of total temperature and total pressure. Surface pressure measurements are available on the vane at midspan, and on the blade at 50% and 90% spans as well as the rotor shroud. In addition, temperature and pressure measurements obtained inside the coolant cavities of both the vanes and blades are presented. Time-averaged values for the surface pressure on the vane and blade are compared to steady CFD predictions. Additional comparisons will be made between the heat transfer on cooled blades and uncooled blades with identical surface geometry. This, along with measurements of adiabatic wall temperature, will provide a basis for analyzing the effectiveness of the film-cooling scheme at a number of locations.
Syngas Capable Combustion Systems Development for Advanced Gas Turbines
Authors: Gadde Satish , Wu Jianfan , Gulati Anil , McQuiggan Gerry , Koestlin Berthold , Prade Bernd
Published: September 2008

In the age of volatile and ever increasing natural gas fuel prices, strict new emission regulations and technological advancements, modern IGCC plants are the answer to growing market demands for efficient and environmentally friendly power generation. IGCC technology allows the use of low cost opportunity fuels, such as coal, of which there is a more than a 200-year supply in the U.S., and refinery residues, such as petroleum coke and residual oil. Future IGCC plants are expected to be more efficient and have a potential to be a lower cost solution to future CO2 and mercury regulations compared to the direct coal fired steam plants. Siemens has more than 300,000 hours of successful IGCC plant operational experience on a variety of heavy duty gas turbine models in Europe and the U.S. The gas turbines involved range from SGT5-2000E to SGT6-3000E (former designations are shown on Table 1). Future IGCC applications will extend this experience to the SGT5-4000F and SGT6-4000F/5000F/6000G gas turbines. In the currently operating Siemens’ 60 Hz fleet, the SGT6-5000F gas turbine has the most operating engines and the most cumulative operating hours. Over the years, advancements have increased its performance and decreased its emissions and life cycle costs without impacting reliability. Development has been initiated to verify its readiness for future IGCC application including syngas combustion system testing. Similar efforts are planned for the SGT6-6000G and SGT5-4000F/SGT6-4000F models. This paper discusses the extensive development programs that have been carried out to demonstrate that target emissions and engine operability can be achieved on syngas operation in advanced F-class 50 Hz and 60 Hz gas turbine based IGCC applications.