bluuebunny/crossref_metadata_2025 huggingface dataset:
High Intensity, Large Length-Scale Freestream Turbulence Generation in a Transonic Turbine Cascade
Authors: Nix A. C. , Smith A. C. , Diller T. E. , Ng W. F. , Thole K. A.
Published: February 2009

Heat transfer predictions in gas turbine engines have focused on cooling techniques and on the effects of various flow phenomena. The effects of wakes, passing shock waves and freestream turbulence have all been of primary interest to researchers. The focus of the work presented in this paper is to develop a turbulence grid capable of generating high intensity, large-scale turbulence for use in experimental heat transfer measurements in a transonic facility. The grid is desired to produce freestream turbulence characteristic of the flow exiting the combustor of advanced gas turbine engines. A number of techniques are discussed in this paper to generate high intensity, large length-scale turbulence for a transonic facility. Ultimately, the passive grid design chosen is capable of producing freestream turbulence with intensity of approximately 10–12% near the entrance of the cascade passages with an integral length-scale of 2 cm.
Limits and Trade-Off in the Control of Compressor Surge
Authors: Blanchini Franco , Giannattasio Pietro , Micheli Diego , Pinamonti Piero
Published: February 2009

The present paper deals with several problems arising in the stabilisation of surge in compression systems. From a theoretical standpoint the system requires a high gain type controller to be stabilised. On the other hand, the real system is affected by persistent measurement noise whose negative effect on stability is strongly amplified by the high gain. Therefore, a suitable filtering of the system output is necessarily required. The bandwidth of the filter is subject to opposite constraints: if it is too large it affects the attenuation property; if it is too narrow, the large phase-lag introduced at low frequencies may compromise the system stabilisation, which requires a fast actuator reaction. This paper analyses all these aspects concurring in the stabilisation problem and the consequent trade-off in the control design. The results of experimental and numerical studies are provided with reference to the active control of surge in a multistage centrifugal compressor.
The Effect of Water Vapor on Oxidation Performance of Alloys Used in Recuperators
Authors: Pint Bruce A. , More Karren L. , Tortorelli Peter F.
Published: February 2009

The use of a recuperator to recover waste heat from the exhaust gases is one method for improving a microturbine’s energy efficiency. This study looked at the effect of water vapor in the exhaust gas on the oxidation resistance of a current technology stainless steel and several high performance replacement alloys. Alloys of interest are high-Cr, Ni-base superalloys such as alloy 625 and aluminum-containing alloys such as Haynes alloy 214 and Plansee alloy PM2000, which is an oxide-dispersed FeCrAl. The latter two alloys form a protective external alumina scale which is more resistant to water vapor environments than chromia scales. Scanning and transmission electron microscopy characterization of the specimen surface oxides after laboratory exposures showed only minor effects of the addition of water vapor to the environment, which is consistent with the excellent corrosion resistance of these high performance alloys.
Inlet Fogging of Gas Turbine Engines: Part C — Fog Behavior in Inlet Ducts, CFD Analysis and Wind Tunnel Experiments
Authors: Chaker Mustapha , Meher-Homji Cyrus B. , Mee Thomas
Published: February 2009

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade yet not a single technical paper treating the physics and engineering of the fogging process, droplet size measurement, droplet kinetics, or the duct behavior of droplets, from a gas turbine perspective, is available. This paper along with Parts A and B provides the results of extensive experimental and theoretical studies conducted over several years coupled with practical aspects learned in the implementation of nearly 500 inlet fogging systems on gas turbines ranging in power from 5 to 250 MW. In part C of this paper, the complex behavior of fog droplets in the inlet duct is addressed and experimental results from several wind tunnel studies are covered.
User Experience With P&W FT8 and GE Frame 6 Cogeneration Power Plants
Authors: Holzschuh Thomas , Kovacik Miroslav
Published: February 2009

In 1996, Cogeneration-Kraftwerke Management Steiermark (CMST), OMV Cogeneration, together with local partners, built a 25Mwel gas turbine plant with a hot water boiler for thermal energy to be used by a car manufacturer and the municipality Graz, Austria. The plant is driven by a FT8-30 (JT8D-219) Pratt & Whitney (P&W) jet engine, accumulating 8200 operating hours per annum. This paper outlines the technical experience and related problems with the existing equipment in the light of variable operating conditions and the investments for efficiency augmentation of the gas turbine trains. A joint-venture between Cogeneration Kraftwerke Management Obero¨sterreich GmbH (CMOO¨) and OMV Cogeneration GmbH as well as Energie AG. CMOO¨ has operated the Combined Heat Power CHP Plant (50 MW el) in the paper mill SCA GRAPHIC LAAKIRCHEN based on contracting since 1994. Because of a extension of the paper mill the energy supply had to be increased. So the delivery of two steam boilers with each 30 t steam per hour and water treatment took place in August 2001. The plant-extension will operate as an independent unit and will guarantee the full availability of the energy supply. Commercial operation will start in January 2002.
Prediction of Combustion Efficiency and NOx Levels for Diffusion Flame Combustors in HAT Cycles
Authors: Belokon Alexandr A. , Khritov Konstantin M. , Klyachko Lev A. , Tschepin Sergey A. , Zakharov Vladimir M. , Opdyke George
Published: February 2009

Diffusion flame combustor test results are presented for methane firing in steam/air mixtures containing up to 20% steam. The tests were conducted at atmospheric pressure with combustor inlet temperatures up to 700K. Steam and air were fully premixed before combustion. Combustion efficiency and NOX levels were measured. The well-known Θ loading parameter was modified by replacing the combustor inlet temperature with the flame temperature. The flame temperature was defined as the stoichiometric temperature of the steam/air mixture. The combustion efficiency obtained with and without steam correlated nicely with this modified loading parameter. Calculated NOX levels agreed well with the measurements, where NOX was predicted using the flamelet technique. This approach makes it possible to predict combustor efficiencies with steam by using combustor performance data taken without steam. Preliminary design analyses of gas turbine cycles with significant steam addition can now easily include the impact of the steam on combustor performance.
A Universal Mathematical Model for a New Combined-Cycle, Fossil-Fuel Power System (LAJ Cycle): Part 1 — Static Model
Authors: Judkins Roddie R. , Armstrong Timothy R. , Labinov Solomon D.
Published: February 2009

A universal mathematical model (UMM) has been developed and applied to the LAJ (for Labinov, Armstrong, and Judkins) cycle, a new combined-cycle, fossil-fuel power system. The UMM includes static and dynamic models of the system. The static model allows for thermodynamic and thermochemical analyses of the basic system components (reformer, turbine, membrane separator, fuel cell, air compressor, heat exchanger, and other components) and the entire system. Equilibrium compositions of reforming products are defined by minimizing Gibbs free energy of the mixtures using the Lagrangian multiplier method. The dependence of the main system parameters on pressure (P), temperature (T), and water-to-methane molar ratios (N) at the steam reformer have been evaluated. For selected reforming parameters, viz., P = 4.0 MPa and T = 1200 K, the degree of methane conversion is near 95% with N = 5. However, in view of mass and size limitations on equipment, a lower value of N = 3 is preferred, in which case the degree of methane conversion is 88%. The dependence of the system static model parameters on N has been investigated, and economic characteristics of the model have been evaluated for an output power of 250 kW. It is shown that when, N = 3, the fuel cost contribution to overall electricity costs is 1 cent/kWh.
Accelerating Turbomachinery Design
Authors: Jarrett Jerome P. , Dawes William N. , Clarkson P. John
Published: February 2009

It is widely accepted that a company’s market penetration, and hence its profitability, is very closely linked to the speed with which it can produce a new design. This paper describes a method which aims to assist the designer in producing higher performance turbomachinery designs more quickly by accelerating the process by which they are produced. The adopted approach, based on a recently derived model of the turbomachinery design process, combines an enhanced version of the ‘Signposting’ design process management methodology with industry-standard analysis codes and CFD, permitting process-wide iteration, near instantaneous generation of guidance data for the designer and fully automatic data handling. A highly successful laboratory experiment based on the design of a large High Pressure Steam Turbine is described and this leads on to current work which incorporates the extension of the proven concept to a full industrial application for the design of Aeroengine Compressors with Rolls-Royce.
Adaptive Selection of Aircraft Engine Technologies in the Presence of Risk
Authors: Roth Bryce , Graham Matthew , Mavris Dimitri , Macsotai Noel
Published: February 2009

The objective of this paper is to describe a method for selecting optimal engine technology solution sets while simultaneously accounting for the presence of technology risk. This method uses a genetic algorithm in conjunction with Technology Identification, Evaluation, and Selection methods to find optimal combinations of technologies. The unique feature of this method is that the technology evaluation itself is probabilistic in nature. This allows the performance impact and associated risk of each technology to be quantified in terms of a distribution on key engine technology metrics. The resulting method can best be characterized as a concurrent genetic algorithm/Monte Carlo analysis that yields a performance- and risk-optimal technology solution set. This solution set is inherently a robust solution because the method will naturally strive to find those technologies representing the best compromise between performance improvement and technology risk. Finally, a practical demonstration of the method and accompanying results is given for a typical commercial aircraft engine technology selection problem.
An Improved Long Life Duration CMC for Jet Aircraft Engine Applications
Authors: Bouillon Eric , Lamouroux Franck , Baroumes Laurent , Cavalier Jean Claude , Spriet Patrick , Habarou Georges
Published: February 2009

A new concept of Ceramic Matrix Composite (CMC), mainly based on the use of a self–sealing technology for matrix and the use of a multilayer woven reinforcement, has been developed by Snecma for achieving high performance levels targeted by future jet engines. The driving force for this development has been to increase both lifetime and temperature capability of previous C/SiC and SiC/SiC materials using a monolithic SiC Chemical Vapor Infiltration (CVI) matrix and finishing treatment against oxidation. The first material, which has been developed with this new approach, is CERASEP® A410, using Hi-Nicalon™ fibers from Nippon Carbon. It has been submitted to a comprehensive characterization in order to determine thermo-mechanical properties and to evaluate lifetime duration, using fatigue and creep testing. Further material development is investigating the use of carbon fiber for economical objectives. The combination of such fibers with the new self-sealing matrix is providing promising results for long duration application at high temperature. Such results are permitted by the very high potential of the new matrix.
Development and Evaluation of Ceramic Components for Gas Turbine
Authors: Fukudome Takero , Tsuruzono Sazo , Karasawa Wataru , Ichikawa Yoshihiro
Published: February 2009

An 8000 kW class Hybrid Gas Turbine (HGT) project, administered by the New Energy and Industrial Technology Development Organization (NEDO), has been ongoing since July of 1999 in Japan. Targets of this project are improvement in thermal efficiency and output power by using ceramic components, and early commercialization of the gas turbine system. The ceramic components are used for stationary parts subjected to high temperature, such as combustor liners, transition ducts, and first stage turbine nozzles. Development of the gas turbine is conducted by Kawasaki Heavy Industries, Ltd. (KHI), to achieve the Turbine Inlet Temperature (TIT) of 1250°C, thermal efficiency of 34%, NOx emission less than standard regulation values, and 4,000 h engine durability. Kyocera is in charge of the development and evaluation of the ceramic components. Recently, recession of the Si based ceramic materials under the combustion gas is the focus of attention to improve the reliability of ceramic components for gas turbine. For the HGT project, the silicon nitride material (SN282 : silicon nitride material produced by Kyocera Corporation) is used for the components subjected to high temperature. The SN282 was evaluated under the combustion gas, and clear recession was observed. Our technology of the Environmental Barrier Coating (EBC) is under development to obtain reliable heat resistive SN282 components, against the recession by combustion gas. Reliability of the SN282 with EBC has been evaluated by exposure and hydrothermal corrosion test. Ceramic components made of SN282 with EBC will be also evaluated by a proof engine test of 4,000 h, which starts in the spring of 2002.
Effects of the Inlet Flow Conditions on the Tip Clearance Flow of an Isolated Compressor Rotor
Authors: Brandt Holger , Fottner Leonhard , Saathoff Horst , Stark Udo
Published: February 2009

Numerical investigations on the effects of varying inflow conditions on the tip leakage flow field of an isolated low–speed compressor rotor and the respective rotor tip section cascade were performed at corresponding operation points. Inlet flow variations at each flow rate were obtained by means of varying the boundary layer thickness in such a manner that the non-dimensional integral parameters of the simulated inflow boundary layers were identical for the rotor and cascade. In order to describe the flowfield through the tip gap and its interactions with the incoming flow accurately, a fully–gridded tip gap region was employed. The numerical predictions for comparable inflow conditions agree well with experimental results from previous investigations on the endwall boundary layer separation due to tip clearance flow. It is demonstrated by the simulations that thickening the inflow boundary layer forces the roll-up point of the clearance vortex to move towards the leading edge. By its effects upon leakage flow, varying the incoming boundary layer has a deleterious effect on stall mass flow similar to increasing the tip clearance height. The investigations further reveal a great deal of similarity between the steady state clearance flow in the cascade and the rotor overtip leakage flow.
A Numerical Investigation of the Influence of Casing Treatments on the Tip Leakage Flow in a HPC Front Stage
Authors: Wilke I. , Kau H.-P.
Published: February 2009

This paper describes the influence of casing treatments on the tip leakage flow and its resulting vortex. The presented results and conclusions are based on steady state numerical simulations of a high pressure compressor stage. Without casing treatments a significant change of behavior of the tip leakage flow can be observed near surge. This change is termed as vortex breakdown and occurs after passing the shock in the blade passage. The simulations indicate the losses in total pressure inside the vortex core as the main reason for the vortex breakdown. These losses mainly depend on the blade loading. Running the compressor stage at high pressure ratios these losses can reach such a high level that the total pressure inside the vortex measured in the rotating system of the rotor falls below the static pressure after the shock. This pressure difference works as a physical barrier for the low energy vortex core and prevents it from reaching the high pressure rotor outlet. Consequently, this blockage must lead to the onset of recirculation zones — the so called vortex breakdown. Different casing treatments have been tested on their ability to delay vortex breakdown and to move the surge line to lower mass flows. Numerical simulations show that configurations with axial slots as well as circumferential grooves weaken or even destroy the characteristic tip leakage vortex and reduce its resulting losses in total pressure. This reduction in losses delays or prevents the onset of vortex breakdown compared to the untreated case explaining the effectiveness of casing treatments. Observations indicate that casing treatments do not interfere with the vortex directly. The key mechanism seems to lay mainly in the interaction with the tip leakage alone. Taking advantage of existing pressure differences in the rotor blade row casing treatments remove tip leakage flow in zones of high pressure and interrupt temporarily the feeding of the vortex. The separated tip leakage reenters the main flow in zones of low pressure again. The way how this tip leakage bypass is realized defines the influence of casing treatments on efficiency and surge line.
Interstage Injection Into Axial Compressor, Gas Turbine Model 7EA: Part 2
Authors: Ingistov Steve
Published: February 2009

This paper describes the efforts of upgrading the original Interstage Injection System (IIS) that was installed in Gas Turbine Unit (GTU) No2, Summer 2000. Paper presented by Ingistov, No 2001-GT-407 at IGTI Conference in New Orleans, June 2001 describes the original IIS design and its operational results. As presented in New Orleans IGTI Conference the main purpose of Interstage Injection (II) is to preserve the Gas Turbine Unit (GTU) power output rather than augment the power output. Some power augmentation however takes place, and with gradual increase of the injected water flow the power gain will have to be quantified. This paper incorporates design changes of the water injection nozzles and the field results on GTU No1 compiled during Summer and Fall of 2001 in Watson Cogeneration Company (WCC) Plant in Carson California.
Using Gurney Flaps to Control Laminar Separation on Linear Cascade Blades
Authors: Byerley Aaron R. , Sto¨rmer Oliver , Baughn James W. , Simon Terrence W. , Van Treuren Kenneth W. , List Jo¨rg
Published: February 2009

This paper describes an experimental investigation of the use of Gurney flaps to control laminar separation on turbine blades in a linear cascade. Measurements were made at Reynolds numbers (based upon inlet velocity and axial chord) of 28 × 103, 65 × 103 and 167 × 103. The freestream turbulence intensity for all three cases was 0.8%. Laminar separation was present on the suction surface of the Langston blade shape for the two lower Reynolds numbers. In an effort to control the laminar separation, Gurney flaps were added to the pressure surface close to the trailing edge. The measurements indicate that the flaps turn and accelerate the flow in the blade passage toward the suction surface of the neighboring blade thereby eliminating the separation bubble. Five different sizes of Gurney flaps, ranging from 0.6% to 2.7% of axial chord, were tested. The laser thermal tuft technique was used to determine the influence of the Gurney flaps on the location and size of the separation bubble. Additionally, measurements of wall static pressure, profile loss, and blade-exit flow angle were made. The blade pressure distribution indicates that the lift generated by the blade is increased. As was expected, the Gurney flap also produced a larger wake. In practice, Gurney flaps might possibly be implemented in a semi-passive manner. They could be deployed for low Reynolds number operation and then retracted at high Reynolds numbers when separation is not present. This work is important because it describes a successful means for eliminating the separation bubble while characterizing both the potential performance improvement and the penalties associated with this semi-passive flow control technique.
Modelling Trace Element Emissions in Co-Gasification of Sewage Sludge With Coal
Authors: Reed G. P. , Dugwell D. R. , Kandiyoti R.
Published: February 2009

Gasification has attracted considerable interest from water utilities as a sewage sludge disposal option, with the advantages of waste volume reduction, pathogen destruction and energy recovery. Co-gasification with coal in a larger plant (>10 MWt) employing a gas turbine for energy recovery may reduce the risk and cost of this option. However, controlling the release of trace elements such as Pb and Zn in the gas produced may be necessary to avoid corrosion, and to meet environmental requirements. A thermodynamic equilibrium model has been used to make predictions of the speciation of trace elements in the fuel gas from co-gasification of sewage sludge with coal. Experimental data from a pilot scale 2 MWt sewage sludge/coal co-gasification plant with a hot gas filter was used to test the validity of these predictions. No significant amount of Be, Co, Cu, V and Zn was predicted to be in the form of gaseous phase species, and this was confirmed by the experimental data. On the other hand, Hg and Se were predicted to be only present in gas phase species, and this was also confirmed experimentally. The elements As, B, Cd, Pb, Sb and Sn were all predicted to form a larger amount of gaseous species than was observed in the experimental measurements. Refinement of the predictions for As and B by inclusion of specific minor/trace element interactions with Ni and Ca respectively gave a better agreement with the experimental data. Whilst the experimentally-observed lowering of Pb emissions by reduction of the gas cleaning temperature from 580 °C to 450 °C was qualitatively predicted, the concentration of Pb in the fine dust removed by the hot gas filter indicates condensation at higher temperatures than predicted. The absence of thermodynamic data for the more complex minerals and adsorbed species that may be formed is thought to account for some of these differences.
Numerical Investigation of the Sensitivity of Forced Response Characteristics of Bladed Disks to Mistuning
Authors: Myhre M. , Moyroud F. , Fransson T. H.
Published: February 2009

The influence of blade-to-blade coupling and rotation speed on the sensitivity of bladed disks to mistuning is studied. A transonic fan is considered with part span shrouds and without shrouds, respectively, constituting a high and a low blade-to-blade coupling case. For both cases, computations are performed at rest as well as at rotation speeds corresponding to resonant crossings in the Campbell diagram. Mistuning sensitivity is modeled as the dependence of amplitude magnification on the standard deviation of blade stiffnesses. A state of the art finite element reduction technique, based on classical modal analysis, is employed for the structural analysis. This reduced order model is solved for sets of random blade stiffnesses with various standard deviations, i.e. Monte Carlo simulations. In order to reduce the sample size, the statistical data is fitted to a Weibull (type III) parameter model. Three different parameter estimation techniques are applied and compared. The key role of blade-to-blade coupling, as well as the ratio of mistuning to coupling, is demonstrated for the two cases. The mistuning sensitivity behavior of the fan without shrouds is observed to be unaffected by rotation speed at its resonant condition, due to insignificant changes in coupling strength at this speed. The fan with shrouds, on the other hand, shows a significantly different behavior at rest and resonant speed, due to increased coupling under rotation. Comparing the two cases at resonant rotor speeds, the fan without shrouds is less or equally sensitive to mistuning than the fan with shrouds in the entire range of mistuning strengths considered.
A Simple Kinematic Model for the Behavior of a Magnetically Levitated Rotor Operating in Overload Regime
Authors: Cuesta E. N. , Medina L. U. , Rastelli V. R. , Montbrun N. I. , Di´az S. E.
Published: February 2009

Currently, the use of magnetic levitation systems has incremented in lieu of the many advantages they present respect to conventional systems. They provide frictionless operation and thus, a wearless life, eliminate the need for lubricants and allow for active vibration control. However, there are some limitations to their use, the dynamic load capacity is restricted by the magnetic properties of the materials used in their constructions and, therefore, their tolerance to large dynamic loads, such as in the case of blade loss or similar sudden failures, is small. For these cases, as well as for the case of bearing power loss, all commercial magnetic suspensions contain a safety backup system, usually consisting of roller bearings that avoid contact between stationary and rotating parts. The present work analyses the behavior of a rotor supported by a magnetic radial bearing on the non-drive end, which is operated in an overload regime. In this regime, a series of impacts occurs between the rotor and the backup bearing, which results on a highly non-linear system that might become unstable depending on the geometry, the control algorithm, the speed and excitation conditions. A non-linear model is proposed. The equations are separated into two regimes, one when the rotor is levitated and one during contact with the backup bearings; the contact is modeled by kinematic conditions. The magnetic bearing forces are estimated using a non-linear model and a PID algorithm is considered as a system’s control strategy. Rigid body theory for planar collision is considered for description of impacts between the backup bearing and the rotor.
Heat Transfer and Flow Field Measurements in a Rib-Roughened Branch of a Rotating Two-Pass Duct
Authors: Servouze Yves , Sturgis J. Chris
Published: February 2009

Internal cooling of gas engine turbine blades is a critical technology. This paper addresses the subject by presenting the results of an experimental program that uses a rotating, square-cross-section, U-shaped channel to model the blade coolant passage. The channel is heated, instrumented and furnished with angled ribs (60° to flow direction) on two walls of one branch. Air is the coolant. Internal Nusselt numbers are calculated on the four walls at various locations along the flow in both the centrifugal and centripetal branches for two Reynolds numbers (5000, 25000) and several Rotation numbers (0.033, 0.066, 0.1, 0.33). Data indicate greater heat transfer on the trailing wall than leading wall in the centrifugal branch; likewise, for the upper wall compared to the lower wall. Centripetal branch heat transfer is affected by bend effects. Particle Image Velocimetry measurements in both the stationary and rotating channels reveal the presence of vortices. The large number of measurements is useful for comparison with numerical calculations.
Optimization of a Large Number of Coolant Passages Located Close to the Surface of a Turbine Blade
Authors: Dennis Brian H. , Egorov Igor N. , Dulikravich George S. , Yoshimura Shinobu
Published: February 2009

A constrained optimization of locations and discrete radii of a large number of small circular cross-section straight-through coolant flow passages in internally cooled gas turbine vane was developed. The objective of the optimization was minimization of the integrated surface heat flux penetrating the airfoil thus indirectly minimizing the amount of coolant needed for the removal of this heat. Constraints were that the maximum temperature of any point in the vane is less than the maximum specified value and that the distances between any two holes or between any hole and the airfoil surface are greater than the minimum specified value. A configuration with maximum of 30 passages was considered. The presence of external hot gas and internal coolant was approximated by using convection boundary conditions for the heat conduction analysis. A parallel three-dimensional thermoelasticity finite element analysis (FEA) code from the ADVENTURE project at University of Tokyo was used to perform automatic thermal analysis of different vane configurations. A robust semi-stochastic constrained optimizer and a parallel genetic algorithm (PGA) were used to solve this problem using an inexpensive distributed memory parallel computer.
Aspects of Cooled Gas Turbine Modelling for the Semi-Closed O2/CO2 Cycle With CO2 Capture
Authors: Jordal Kristin , Bolland Olav , Klang A˚ke
Published: February 2009

In order to capture the behaviour of the oxyfuel cycle operating with high combustor-outlet temperature, the impact of blade and vane cooling on cycle performance must be included in the thermodynamic model. As a basis for a future transient model, three thermodynamic models for the cooled gas turbine are described and compared. The first model, known previously from the literature, models expansion as a continuous process with simultaneous heat and work extraction. The second model is a simple stage-by-stage model and the third is a more detailed stage-by-stage model that includes velocity triangles and enables the use of advanced loss correlations. An airbreathing aeroderivative gas turbine is modelled, and the same gas turbine operating in an oxyfuel cycle is studied. The two simple models show very similar performance trends in terms of variation of pressure ratio and turbine inlet temperature in both cases. With the more detailed model, it was found that, without any change of geometry, the turbine rotational speed increases significantly and performance drops for the maintained geometry and pressure ratio. A tentative increase of blade angles or compressor pressure ratio is found to increase turbine performance and decrease rotational speed. This indicates that a turbine will require re-design for operation in the oxyfuel cycle.
Design of a Modern Test-Facility for LPT/OGV Flows
Authors: Hja¨rne Johan , Larsson Jonas , Lo¨fdahl Lennart
Published: February 2009

This paper presents a complete design process of a modern test-facility for the investigation of low pressure turbine/outlet guide vane (LPT/OGV) flows. The design is based on modern CFD techniques combined with classical analytical approaches and experimental expertise. The paper describes the design procedure of the diffuser, the settling chamber, the contraction, the inlet section with boundary layer bleeds and the test-section. In the contraction part of the paper a new design method is developed using both separation and relaminarization theory. Finally, full viscous three-dimensional CFD calculations are performed of the test-facility, from the contraction to the test-section, making it possible to assess the flow characteristics of the test-facility before it is even constructed.
Diagnosis for Loose Blades in Gas Turbines Using Wavelet Analysis
Authors: Lim Meng Hee , Leong M. Salman
Published: February 2009

The application of wavelet analysis to diagnose loose blades condition in gas turbines is examined in this paper. Experimental studies were undertaken to simulate loose blades condition occurring in gas turbines in an attempt to understand vibration response associated with loose blades under different operating conditions. Results showed that loose blades were undetectable under steady state operating condition. During turbine coast down, loose blade could be detected based on impactic signals induced by the loose blades on the rotor and thus excited the natural frequencies of the rotor assembly. Results from the coast down condition showed that wavelet analysis was more sensitive and effective than Fourier analysis for loose blade diagnosis. The severity, the number, and the configuration of the loose blades could be potentially estimated based on the pattern of the coast down wavelet map.
Real Gas Effects in Turbomachinery Flows: A CFD Model for Fast Computations
Authors: Boncinelli Paolo , Rubechini Filippo , Arnone Andrea , Cecconi Massimiliano , Cortese Carlo
Published: February 2009

A numerical model was included in a three-dimensional viscous solver to account for real gas effects in the compressible Reynolds Averaged Navier-Stokes (RANS) equations. The behavior of real gases is reproduced by using gas property tables. The method consists of a local fitting of gas data to provide the thermodynamic property required by the solver in each solution step. This approach presents several characteristics which make it attractive as a design tool for industrial applications. First of all, the implementation of the method in the solver is simple and straightforward, since it does not require relevant changes in the solver structure. Moreover, it is based on a low-computational-cost algorithm, which prevents a considerable increase in the overall computational time. Finally, the approach is completely general, since it allows one to handle any type of gas, gas mixture or steam over a wide operative range. In this work a detailed description of the model is provided. In addition, some examples are presented in which the model is applied to the thermo-fluid-dynamic analysis of industrial turbomachines.
Flame Transfer Function Characteristics of Swirl Flames for Gas Turbine Applications
Authors: Lohrmann Martin , Bu¨chner Horst , Zarzalis Nikolaos , Krebs Werner
Published: February 2009

For the suppression or reduction of self-sustained combustion instabilities, modifications of the burner outlet conditions, that strongly influence the dynamic flame response, seem to be the most promising way. Therefore, to derive a detailed physical understanding of the feedback mechanisms the dynamic flame response characteristics, quantified by flame transfer functions, are required in dependence of flame type and operation conditions of the combustor. In the present paper measurements of flame transfer functions of an industrial, full-scale prototype gas turbine burner are discussed. For the detection of periodically-unsteady OH radical radiation (response of the flame) two different UV detection systems were compared. Because the concentration of electronically-excited OH radicals in the reaction zone and therefore, of the measured UV radiation intensity, is strongly depending on volumetric reaction density and local flame temperatures, the UV radiation intensity commonly used for the quantification of the heat release can be misinterpreted. Hence, two different concepts of fuel gas/air mixture formation have been realized in the experiments to separate and to physically interpret the influence of the mixture formation and its quality on the UV radiation intensity of the determined flame transfer functions. The derived understanding of the complex interactions of mixture mass flow oscillations, fluctuations of the mixture composition and the periodic combustion of ring vortices at a full-scale burner is an essential requirement for the interpretation of flame dynamics based on measurements of the UV radiation intensity.
Hybrid Model of an Evaporative Gas Turbine Power Plant Utilizing Physical Models and Artificial Neural Networks
Authors: Olausson Pernilla , Ha¨ggsta˚hl Daniel , Arriagada Jaime , Dahlquist Erik , Assadi Mohsen
Published: February 2009

Traditionally, when process identification, monitoring and diagnostics are carried out for power plants and engines, physical modeling such as heat and mass balances, gas path analysis, etc. is utilized to keep track of the process. This type of modeling both requires and provides considerable knowledge of the process. However, if high accuracy of the model is required, this is achieved at the expense of computational time. By introducing statistical methods such as Artificial Neural Networks (ANNs), the accuracy of the complex model can be maintained while the calculation time is often reduced significantly reduced. The ANN method has proven to be a fast and reliable tool for process identification, but the step from the traditional physical model to a pure ANN model is perhaps too wide and, in some cases, perhaps unnecessary also. In this work, the Evaporative Gas Turbine (EvGT) plant was modeled using both physical relationships and ANNs, to end up with a hybrid model. The type of architecture used for the ANNs was the feed-forward, multi-layer neural network. The main objective of this study was to evaluate the viability, the benefits and the drawbacks of this hybrid model compared to the traditional approach. The results of the case study have clearly shown that the hybrid model is preferable. Both the traditional and the hybrid models have been verified using measured data from an existing pilot plant. The case study also shows the simplicity of integrating an ANN into conventional heat and mass balance software, already implemented in many control systems for power plants. The access to a reliable and faster hybrid model will ultimately give more reliable operation, and ultimately the lifetime profitability of the plant will be increased. It is also worth mentioning that for diagnostic purposes, where advanced modeling is important, the hybrid model with calculation time well below one second could be used to advantage in model predictive control (MPC).
Performance Prediction of a Converging Slot-Hole Film-Cooling Geometry
Authors: Sargison J. E. , Guo S. M. , Oldfield M. L. G. , Lock G. D. , Rawlinson A. J.
Published: February 2009

Performance prediction techniques have been investigated for use as design tools for the novel console, or converging slothole, film cooling geometry. The performance of the console has been the subject of earlier publications that have demonstrated that this new film cooling hole improves both the heat transfer and aerodynamic performance of turbine vane and rotor blade cooling systems. Three prediction techniques are used and compared in this paper: theoretical models, correlations of experimental data, and two-dimensional Computational Fluid Dynamics. Published experimental measurements of adiabatic effectiveness for the console, and other typical cooling holes at low speed conditions and coolant to mainstream momentum flux ratios of 0.5, 1.1 and 1.5 were used in this analysis. The console results were compared with theoretical predictions of adiabatic effectiveness using a slot model, which was found to be an adequate approximation. Experimental performance data measured in a simple, low-speed apparatus was correlated and used to predict the performance of multiple rows of consoles in a nozzle guide vane at engine representative conditions. This was compared with published experimental data for engine representative conditions and it was found that the correlated low-speed data provided an adequate and simple prediction of the performance of the console in an engine representative film cooling design. Two-dimensional Computational Fluid Dynamics is another relatively rapid prediction tool that was used to predict low speed results.
Development of Micro-Turbo Charger and Micro-Combustor as Feasibility Studies of Three-Dimensional Gas Turbine at Micro-Scale
Authors: Isomura Kousuke , Murayama Motohide , Yamaguchi Hiroshi , Ijichi Nobuaki , Saji Nobuyoshi , Shiga Osamu , Takahashi Katsuyoshi , Tanaka Shuji , Genda Takashi , Esashi Masayoshi
Published: February 2009

A gas turbine at micro-scale is under development at Tohoku University in conjunction with Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI). The development of the engine is currently at the stage of experimentally proving the component performance required to realize the Brayton cycle. The component tests are split into two activities at current stage to separate the effect of the heat transfer from the combustor to the compressor, which was shown to have large effect on the component efficiency, by previous studies. Current objective of the tests is to clarify whether the gas turbine at micro-scale is feasible from the point of performance change due to the scaling effect. A micro-turbocharger has been developed to prove the performance of the compressor and the bearing. It has been started operating and the micro-turbocharger tests are currently underway. Micro-combustors have been developed to find the appropriate configuration of the micromachine gas turbine. It has successfully been designed and tested to achieve 99.9% of combustion efficiency with both Hydrogen and Methane fuel.
Numerical Calculation of Low Order Blade Excitation in Pulse Charged Axial Turbocharger Turbines and Its Experimental Assessment
Authors: Filsinger D. , Scha¨fer O.
Published: February 2009

Pulse charged turbocharger turbines are exposed to highly unsteady aerodynamic forces, which cause substantial blade vibrations. With respect to high cycle fatigue, the determination of the resonant vibration responses of the turbocharger blades rotating with variable speed is of great importance for a reliable and safe design. The first step to a numerical prediction of the blade’s loading by oscillations in low orders is the calculation of the aerodynamic excitation. This paper contains results of a study, which has been carried out at ABB Turbo Systems Ltd., to define the necessary numerical effort for the calculation of the low order blade excitation in pulse charged axial turbocharger turbines by means of computational fluid dynamics. The paper presents comparisons between experimental and numerical results concerning the unsteady loading of pulse charged axial turbocharger turbines. It shows the potential of quasi-three-dimensional computational fluid dynamics to predict the dynamic blade loading under real engine operation.
Boundary Layer Measurement on the Blade Surface of a Multi-Stage Axial Flow Compressor
Authors: Shin Y. H. , Elder R. L. , Bennett I.
Published: February 2009

This study presents experimental investigations into blade suction surface boundary layer flow in a multistage axial flow compressor. The experiments were focused on the third stage of the 4-stage Low Speed Research Compressor (LSRC) at Cranfield University. Measurements within the boundary layer were obtained using a hot wire probe. This was traversed normal to the blade surface at small increments, capturing the unsteady velocity profile within the boundary layer. Detailed boundary layer flow measurements covering most of the stator suction surface were taken and are described using time mean and ensemble averaged velocity profiles. Turbulence intensity in the boundary layer flow on the blade suction surface is also discussed. A strong wake-induced strip zone due to passing wake disturbances are generated at midspan near the blade leading edge at rotor blade passing frequency. Corner separation was observed at the tip region near the trailing edge. Normalized velocity profiles in this region show no variation in time.
Experimental Investigation of Unsteady Flow Field in the Tip Region of an Axial Compressor Rotor Passage at Near Stall Condition With SPIV
Authors: Liu Baojie , Wang Hongwei , Liu Huoxing , Yu Hongjun , Jiang Haokang , Chen Maozhang
Published: February 2009

Stereoscopic Particle Image Velocimetry (SPIV) was applied to a large-scale low-speed compressor facility with the configuration of the two CCD cameras placed on each side of the light sheet to make the measurement of the vortices in the cross flow section possible and to avoid the disturbance from the light sheet containing periscope-type probe. Instantaneous velocity and vorticity distributions were successfully documented at the tip region of the rotor at near stall condition. The measurement results clearly revealed the generation and evolution of the tip leakage vortex. Comparing to design condition, the tip leakage vortex at near stall condition generates and breaks down earlier and interacts more violently with mainstream, which causes large blockage and much loss. Whether corner vortex exists or not is the primary difference between near stall and design condition. Differing from the leakage vortex, the corner vortex is composed of multiple vortices developed from the suction surface of the rotor blade. The key mechanism for the generation of the corner vortex is that the rotation of the rotor has different effect on the evolution of positive vortices and negative vortices, which makes the positive vortices dissipates faster than the negative ones, the vortices at the rotor exit therefore bear mainly negative vortices, which induces the fluids to rotate clockwise at the corner and forms the corner vortex.
A Feasibility Study of Inverted Brayton Cycle for Gas Turbine Repowering
Authors: Bianchi M. , di Montenegro G. Negri , Peretto A. , Spina P. R.
Published: February 2009

In the present paper a feasibility study of Inverted Brayton Cycle (IBC) engines, for the repowering of existing gas turbines, is presented. The following main phases have been carried out: i) identification of the more suitable gas turbines to be repowered by means of an IBC engine; ii) designing of the IBC components. Once the IBC engines for the candidate gas turbines were designed, an analysis has been developed to check the possibility to match these engines with other gas turbines, similar to those for which the IBC engines have been designed. In all the analyzed cases the evaluated performance result only slightly worse than that obtainable by repowering the same gas turbine with IBC engines “ad hoc” designed.
Dry, Low Emissions for the ‘H’ Heavy-Duty Industrial Gas Turbines: Full-Scale Combustion System Rig Test Results
Authors: Myers Geoff , Tegel Dan , Feigl Markus , Setzer Fred , Bechtel William , Fitts David , Couture Bernard , Tuthill Richard
Published: February 2009

The lean, premixed DLN2.5H combustion system was designed to deliver low NOx emissions from 50% to 100% load in both the Frame 7H (60 Hz) and Frame 9H (50 Hz) heavy-duty industrial gas turbines. The H machines employ steam cooling in the gas turbine, a 23:1 pressure ratio, and are fired at 1440 C (2600 F) to deliver over-all thermal efficiency for the combined-cycle system near 60%. The DLN2.5H combustor is a modular can-type design, with 14 identical chambers used on the 9H machine, and 12 used on the smaller 7H. On a 9H combined-cycle power plant, both the gas turbine and steam turbine are fired using the 14-chamber DLN2.5H combustion system. An extensive full-scale, full-pressure rig test program developed the fuel-staged dry, low emissions combustion system over a period of more than five years. Rig testing required test stand inlet conditions of over 50 kg/s at 500 C and 28 bar, while firing at up to 1440 C, to simulate combustor operation at base load. The combustion test rig simulated gas path geometry from the discharge of the annular tri-passage diffuser through the can-type combustion liner and transition piece, to the inlet of the first stage turbine nozzle. The present paper describes the combustion system, and reports emissions performance and operability results over the gas turbine load and ambient temperature operating range, as measured during the rig test program.