bluuebunny/crossref_metadata_2025 huggingface dataset:
Metal Temperature Map Determination of a Serviced Gas Turbine Bucket and Comparison With FEM Temperature Distribution
Authors: Mastromatteo Francesco , Mammoliti Fabrizio , Giannozzi Massimo , Romanelli Marco , Ficorilli Daniele
Published: September 2008

Nickel-based superalloys are widely used in manufacturing of several important components of aeronautics and land based gas turbines. The good high temperature resistance of these materials is due to their particular microstructure consisting of a FCC lattice nickel matrix, called γ, strengthened by precipitation of a coherent second phase Ni3(Ti,Al) known as γ′. During service at very high temperatures, γ′ precipitates tend to lose their initial configuration and change their size, shape and distribution, so decreasing material properties, in particular creep resistance. In this work the evolution of microstructure in a serviced first stage bucket from a GE machine has been examined. Several cross sections taken at different heights along the airfoil have been observed by SEM, obtaining a detailed map of the microstructure in the component. A quantitative evaluation of service temperature in the different areas has then been achieved by γ′ precipitates size determination by means of image analysis, combined with a γ′ coarsening model optimized for the particular alloy in use. Temperature values so obtained have been compared with those resulting from the finite element method (FEM) temperature distribution performed during design stage.
Aircraft Engine Simulation Project for Undergraduate Propulsion Course
Authors: Sexton Michael R. , Sexton Wayne R.
Published: September 2008

This paper describes a jet engine simulation project assigned to mechanical engineering students in a senior level course in aircraft propulsion systems. The project introduces the students to the methods of engine system analysis and design based on computer simulation. The project statement provides the students with the design point operating characteristics such as engine inlet conditions, pressure ratios, and static thrust developed, which are necessary to develop a design point thermodynamic model. After topics in cycle analysis and engine component performance are introduced the students can develop the system of equations necessary to model the engine system and use this model to predict the off-design performance (speed, thrust, efficiency, etc.) of the engine. Off-design conditions resulting from changes in throttle setting, aircraft speed, altitude, and environmental conditions are considered.
An Investigation Into the Uncertainty of Turbomachinery Disc Heat Transfer Calculations Using Monte Carlo Simulation Methods
Authors: Cooke Adam , Childs Peter , Long Christopher
Published: September 2008

The uncertainty in heat transfer data derived from theoretical turbomachinery disc temperatures has been investigated using Monte Carlo simulation methods. Two specific test cases of relevance to turbine disc heat transfer have been considered, a free disc with laminar flow and a free disc with turbulent flow. This study explores and quantifies uncertainties for the test cases considered by looking at three factors: measurement noise, the order of magnitude of the polynomial fit used for interpolation through the data points and the number of data points utilised within the polynomial. The local heat flux uncertainty arising from using a 5th order polynomial for the laminar case varied between approximately ± 40 % and ± 600 % and for the turbulent case between approximately ± 4 % and ± 1000 %. This study provides guidelines for similar analyses and the resulting uncertainty and how test data can be presented.
Operation on Process Off-Gas of a 24MW SGT-600 Gas Turbine on an LNG Plant in China
Authors: Strand Torsten
Published: September 2008

A privately owned LNG plant was taken into service at the Tuha Oil Fields in western China during 2004. The plant is the first of its kind and will produce Liquefied Natural Gas (LNG) from associated gas from the oil fields. The LNG is delivered to Central China by trucks. The plant was delivered by Tractebel with Linde AG being responsible for the LNG process design. The compression set of the refrigeration cycle consists of a three-stage Ebara compressor driven by a 24 MW Siemens SGT-600 gas turbine operating on the off-gas from the LNG plant. The operation of the gas turbine integrated in this plant is associated with some special challenges: • the ambient conditions out in the desert; • the fuel, that varies from natural gas to a process gas consisting of methane diluted with up to 28% nitrogen; • the refrigeration medium, which is circulated by the gas turbine driven compressor, changes in composition dependent on load; • the starting procedure with the compressor in the refrigeration loop. A combustion test was performed to verify that the DLE combustion system could accept the variations in gas composition. The control system was modified to handle the variable gas qualities in the fuel and in the refrigeration loop. Since the gas turbine/compressor set is an integrated part of the LNG process the commissioning was a long process governed by the LNG plant commissioning. It included some unexpected events. Now all is working well. It has been shown that a standard SGT-600 DLE unit can start and operate reliably and with low emissions on very much diluted natural gases. The paper contains a brief description of the LNG plant, definition of the special requirements on the gas turbine, a description of the combustion verification test on diluted gas, some events during commissioning and finally the engine verification test.
Simulation of Producer Gas Fired Power Plants With Inlet Fog Cooling and Steam Injection
Authors: Yap Mun Roy , Wang Ting
Published: September 2008

Biomass can be converted to energy via direct combustion or thermo-chemical conversion to liquid or gas fuels. This study focuses on burning producer gases derived from gasifying biomass wastes to produce power. Since the producer gases are usually low calorific values (LCV), the power plants performance under various operating conditions has not yet been proven. In this study, system performance calculations are conducted for 5MWe power plants. The power plants considered include simple gas turbine systems, steam turbine systems, combined cycle systems, and steam injection gas turbine systems (STIG) using the producer gas with low calorific values at approximately 30% and 15% of the natural gas heating value (on a mass basis). The LCV fuels are shown to impose high back compressor pressure and produces increased power output due to increased fuel flow. Turbine nozzle throat area is adjusted to accommodate additional fuel flows to allow compressor operate within safety margin. The best performance occurs when the designed pressure ratio is maintained by widening nozzle openings, even though the TIT is reduced under this adjustment. Power augmentations under four different ambient conditions are calculated by employing gas turbine inlet fog cooling. Comparison between inlet fog cooling and steam injection using the same amount of water mass flow indicates that steam injection is less effective than inlet fog cooling in augmenting power output. Maximizing steam injection, at the expense of supplying the steam to the steam turbine, significantly reduces both the efficiency and the output power of the combined cycle. This study indicates that the performance of gas turbine and combined cycle systems fueled by the LCV fuels could be very different from the familiar behavior of natural gas fired systems. Care must be taken if on-shelf gas turbines are modified to burn LCV fuels.
Experimental Validation of Quasi-Steady Assumption in Modelling of Unsteady Film-Cooling
Authors: Bernsdorf Stefan , Rose Martin G. , Abhari Reza S.
Published: September 2008

This paper reports on the validation of the assumption of quasi steady behaviour of pulsating cooling injection in the near hole flow region. The respective experimental data are taken in a flat plate wind tunnel at ETH Zu¨rich. The facility simulates the film cooling row flow field on the pressure side of a turbine blade. Engine representative non-dimensionals are achieved, providing a faithful model at larger scale. Heating the free stream air and strongly cooling the coolant gives the required density ratio between coolant and free-stream. The coolant is injected with different frequency and amplitude. The three dimensional velocities are recorded using non-intrusive PIV, seeding is provided for both air streams. Two different cylindrical hole geometries are studied, with different angles. Blowing ratio is varied over a range to simulate pressure side film cooling. The general flow field, the jet trajectory and the streamwise circulation are utilized in the validation of the quasi steady assumption.
Experimental Investigation of Turbine Leakage Flows on the 3D Flow Field and End Wall Heat Transfer
Authors: Rehder Hans-Ju¨rgen , Dannhauer Axel
Published: September 2008

Within a European research project the tip end wall region of LP turbine guide vanes with leakage ejection was investigated at DLR in Go¨ttingen. For this purpose a new cascade wind tunnel with three large profiles in the test section and a contoured end wall was designed and built up, representing 50% height of a real low pressure turbine (LPT) stator and simulating the casing flow field of shrouded vanes. The effect of tip leakage flow was simulated by blowing air through a small leakage gap in the end wall just upstream of the vane leading edges. Engine relevant turbulence intensities were adjusted by an active turbulence generator mounted in the test section inlet plane. The experiments were performed with tangential and perpendicular leakage ejection and varying leakage mass flow rates up to 2%. Aerodynamic and thermodynamic measurement techniques were employed. Pressure distribution measurements provided information about the end wall and vane surface pressure field and its variation with leakage flow. Additionally streamline pattern (local shear stress directions) on the walls were detected by oil flow visualization. Downstream traverses with 5-hole pyramid type probes allow a survey of the secondary flow behavior in the cascade exit plane. The flow field in the near end wall area downstream of the leakage gap and around the vane leading edges was investigated using a 2D Particle Image Velocimetry (PIV) system. In order to determine end wall heat transfer distributions, the wall temperatures were measured by an infra-red camera system, while heat fluxes at the surfaces were generated with electric operating heating foils. It turned out from the experiments that distinct changes in the secondary flow behavior and end wall heat transfer mainly occur when the leakage mass flow rate is increased from 1% to 2%. Leakage ejection perpendicular to the main flow direction amplifies the secondary flow, in particular the horse-shoe vortex, whereas tangential leakage ejection causes a significant reduction of this vortex system. For high leakage mass flow rates the boundary layer flow at the end wall is strongly affected and seems to be highly turbulent, resulting in entirely different heat transfer distributions.
Enhanced External Aerodynamic Performance of a Generic Combustor Using an Integrated OGV/Pre-Diffuser Design Technique
Authors: Walker A. Duncan , Carrotte Jon F. , McGuirk James J.
Published: September 2008

The paper uses experimental measurements to characterise the extent that improved external aerodynamic performance (reduced total pressure loss, increased flow quality) of a gas-turbine combustion system may be achieved by adopting an integrated OGV/pre-diffuser technique. Two OGV/pre-diffuser combinations were tested. The first is a datum design corresponding to a conventional design approach, where OGV and pre-diffuser are essentially designed in isolation. The second is an ‘integrated’ design where the OGV blade shape has been modified, following recommendations of earlier CFD work ([14]), to produce a secondary flow/wake structure that allows the pre-diffuser to operate at a higher area ratio without boundary layer separation. This is demonstrated to increase static pressure recovery and reduce dump losses. Experimental measurements are presented on a fully annular rig. Several traverse planes are used to gather 5-hole probe data which allow the flow structure through the OGV, at inlet and exit of the pre-diffuser, and in the inner/outer annulus supply ducts to be examined. Both overall performance measures (loss coefficients) and measures of flow uniformity and quality are used to demonstrate that the integrated design is superior.
MS7001EA Gas Turbine Stage 3 Up-Rate: Design and Field Validation
Authors: Andrew Philip L. , Krishnakumar Poorna , Smith Bruce L. , Snook Daniel D. , Schmitt Thomas P.
Published: September 2008

The time-proven MS7001EA Gas Turbine has undergone several compressor flow and firing-temperature up-rates over its life cycle to date. These up-rates, while improving output, cumulatively have driven the last stage of the turbine component away from its optimum, design-point efficiency. This paper describes an aerodynamic re-design of the last stage of the 7EA to restore its entitlement component efficiency, thus promoting Customer success through reduced heat rate and increased output. A number of patented mechanical design enhancements have also been applied in support of the aerodynamic re-design. This paper describes the application of technologies leveraged from GE Transportation, Global Research, and Energy to enhance and validate the design of the 7EA last-stage turbine nozzle and bucket. Fully-viscous, steady, 3-D Navier-Stokes analysis was applied to improve the hub reaction, lower the nozzle and bucket peak suction-surface Mach Number, and to lower the circumferential swirl component of flow exiting the turbine and entering the exhaust diffuser. A linearized unsteady CFD analysis, in conjunction with cyclic symmetry modal analysis, was applied to ensure that the aeromechanical integrity of the new design was equal to, or better than the field-proven baseline design. Back-to-back precision performance field-testing was conducted to validate the design intent performance enhancement of the re-designed stage, wherein a significant improvement in power and heat rate was demonstrated. Since installation of the redesigned Stage 3 in March, 2005, the lead 7E turbine has accumulated more than 3,900 hours and 14 starts. The re-design has been installed in a total of three units, with a total of more than 10,050 hours of successful operation. Future plans include scaling this design to the GE Frame 9E in service for 50-Hertz power-generation, and to the Frame 6B for 50 and 60 Hertz power generation applications.
The Influence of Atmospheric Conditions on the Performance of Combined Cycle Gas Turbine Power Plants
Authors: Valde´s Manuel , Rovira Antonio , Ferna´ndez Jose´ A.
Published: September 2008

This paper deals with the calculation of the ambient conditions influence on combined cycle gas turbine (CCGT) power and efficiency. The main parameters influencing the CCGT performances when ambient conditions change are the air density and the steam condenser pressure. An 800 MW CCGT is studied in order to obtain numerical results in a particular case. This power plant is analyzed working with different condenser cooling techniques (direct or indirect cooling with open or closed circuits) at both 100% and 50% load. The results show that power output drops by 0.60% to 0.65% are to be expected for every 1 °C rise in ambient temperature and by 0.13% to 0.14% for every 1 mbar decrease in ambient pressure. The efficiencies are affected to a lesser extent since some of the gas turbine waste energy is recovered in the heat recovery steam generator and the steam turbine power is almost constant.
Nonintrusive Flowfield, Temperature and Species Measurements on a Generic Aeroengine Combustor at Elevated Pressures
Authors: Hassa Christoph , Willert Chris , Fischer Michael , Stockhausen Guido , Ro¨hle Ingo , Meier Wolfgang , Wehr Lorin , Kutne Peter
Published: September 2008

A generic combustor was built, that gives wide optical access at higher pressure and shares typical features with aero engine combustors. A comprehensive data set for validation of RANS and LES codes was generated at isothermal as well as combusting conditions at 2 and 10 bars with 650 K preheat using natural gas as fuel. The velocity field was measured using LDA (Laser Doppler Anemometry) and DGV (Doppler Global Velocimetry) as well as PIV (Particle Image Velocimetry). Temperature data were acquired using CARS (Coherent Anti stokes Raman Scattering) and SRS (Spontaneous Raman Scattering). Major species concentrations as well as the mixture fraction in the primary zone of the combustor were also measured using SRS. Mean and RMS values of the temperature measured by CARS in the secondary zone illustrate the influence of the jet impingement on the unsteady mixing of the jets with the swirling primary air.
High Resolution Film Cooling Effectiveness Comparison of Axial and Compound Angle Holes on the Suction Side of a Turbine Vane
Authors: Waye Scot K. , Bogard David G.
Published: September 2008

Film cooling adiabatic effectiveness for axial and compound angle holes on the suction side of a simulated turbine vane was investigated to determine the relative performance of these configurations. The effect of the surface curvature was also evaluated by comparing to previous curvature studies and flat plate film cooling results. Experiments were conducted for varying coolant density ratio, mainstream turbulence levels, and hole spacing. Results from these measurements showed that for mild curvature, 2r/d ≈ 160, flat plate results are sufficient to predict the cooling effectiveness. Furthermore, the compound angle injection improves adiabatic effectiveness for higher blowing ratios, similar to previous studies using flat plate facilities.
High Resolution Film Cooling Effectiveness Measurements of Axial Holes Embedded in a Transverse Trench With Various Trench Configurations
Authors: Waye Scot K. , Bogard David G.
Published: September 2008

Adiabatic film cooling effectiveness of axial holes embedded within a transverse trench on the suction side of a turbine vane was investigated. High resolution two dimensional data obtained from IR thermography and corrected for local conduction provided spatial adiabatic effectiveness data. Flow parameters of blowing ratio, density ratio, and turbulence intensity were independently varied. In addition to a baseline geometry, nine trench configurations were tested, all with a depth of 1/2 hole diameter, with varying widths, and with perpendicular and inclined trench walls. A perpendicular trench wall at the very downstream edge of the coolant hole was found to be the key trench characteristic that yielded much improved adiabatic effectiveness performance. This configuration increased adiabatic effectiveness up to 100% near the hole and 40% downstream. All other trench configurations had little effect on the adiabatic effectiveness. Thermal field measurements confirmed that the improved adiabatic effectiveness that occurred for a narrow trench with perpendicular walls was due a lateral spreading of the coolant and reduced coolant jet separation. The cooling levels exhibited by these particular geometries are comparable to shaped holes, but much easier and cheaper to manufacture.
Acoustics Based Prognostics for DLE Combustor Lean Blowout Detection
Authors: Taware Avinash , Shah Minesh , Wu Pingchuan , Yang Yongsheng , Zhou Jian , Singh Ajai
Published: September 2008

Physics based algorithm that uses acoustic precursors indicating a Lean Blowout (LBO) is proposed for lean blowout detection in combustors. The proposed technology is presented for a typical multi-nozzle Dry Low Emission (DLE) combustor. Three narrow band dynamic pressure tones, namely LBO (low frequency) tone, high fuel to air (F/A) ratio (hot tone) and low F/A ratio (cold) tones are identified as strong precursors to behavior consistent with combustion instability as LBO event evolves. The likelihood of LBO is computed using a statistical model operating on the RMS value of the LBO tone. Two additional pieces of evidential information are built respectively using the relative change of the RMS values of these three tones and the frequency shift of the high F/A tone. A data fusion algorithm then uses these two evidential signatures to enhance the LBO probability based on the LBO tone. Field test results on GE’s commercial multi-nozzle combustor gas turbines showed that the algorithm is practical and effective giving enough lead-time to take corrective action to avoid a blowout. A closed loop controller that modulates global manifold fuel splits for all the combustors or total fuel flow of individual combustor in a multi-combustor (multi-can) turbine to avoid the incipient blowout upon detection using the method presented in this paper can then be easily designed.
Development of Double Gear Fuel Pump for Heat Managment Improvement
Authors: Matsunaga Yasushi , Morioka Noriko , Masuda Seiei , Kurosaki Masahiro
Published: September 2008

A unique double gear fuel pump system with operation mode switching capability for aircraft engines was developed to solve the heat management problem of current high efficiency turbofan engines and improve Specific Fuel Consumption (SFC). Mode switching from parallel operations to series operations was found to reduce the discharge flow and pump work to nearly half. This resulted in the reduction of the rise in fuel temperature due to the fuel re-circulation at the high altitude low Mach number flight condition. Air Cooled Oil Cooler (ACOC) is usually required for sufficient oil cooling at decent or approach flight conditions. Since fuel consumption at those conditions is not very high, most of the gear pump discharge fuel flow proportional to the engine speed is returned to the fuel pump inlet resulting in significant heating. The ACOC that provides additional cooling capability degrades SFC due to not only increased weight but also wasted fan discharge air. By reducing fuel temperature rise at the pump at those flight conditions, the necessity of ACOC may be eliminated. Further, it is shown that a reduction by half of the double gear pump weight can be achieved by increasing pump speed twice (2x) without incurring a durability penalty. Extensive tests showed sufficient steady state pump performance, switching characteristics, and durability.
Static and Dynamic Neural Networks for Simulation and Optimization of Cogeneration Systems
Authors: Zomorodian Roozbeh , Khaledi Hiwa , Ghofrani Mohammad Bagher
Published: September 2008

In this paper, the application of neural networks for simulation and optimization of the cogeneration systems has been presented. CGAM problem, a benchmark in cogeneration systems, is chosen as a case study. Thermodynamic model includes precise modeling of the whole plant. For simulation of the steady sate behavior, the static neural network is applied. Then using dynamic neural network, plant is optimized thermodynamically. Multi layer feed forward neural networks is chosen as static net and recurrent neural networks as dynamic net. The steady state behavior of CGAM problem is simulated by MFNN. Subsequently, it is optimized by dynamic net. Results of static net have excellence agreement with simulator data. Dynamic net shows that in thermodynamic optimization condition, σ and pinch point temperature difference have the lowest value, while CPR reaches a high value. Sensitivity study shows turbomachinery efficiencies have the highest effect on the performance of the system in optimum condition.
Cycle Optimization and Combustion Analysis in a Low-NOx Micro-Gas Turbine
Authors: Cameretti Maria Cristina , Reale Fabrizio , Tuccillo Raffaele
Published: September 2008

The authors discuss in this paper the potential of a method for NOx suppression from power plants based on micro-gas turbines. The method is based on the mild combustion concept, but it needs to be adapted to the actual operating parameters of the micro-turbine, so resulting in an effective employment of the flue gas recirculation for diluting the oxygen in the inlet air. The results are first presented on a thermodynamic basis and some cases are then analyzed with a CFD simulation. Both approaches suggest good perspectives for the nitric oxide control but also highlight some disadvantages in terms of increase in carbon species.
Thermodynamic Optimization of a Combined Cycle Cogeneration Plant With Backpressure Steam Turbine
Authors: Sarabchi K. , Akbarpour R.
Published: September 2008

Cogeneration heat and power plant has a long history of application in many types of industries, buildings etc, because of its benefits, such as environmental, energy and cost saving. A useful type of cogeneration plants is the combined cycle cogeneration plant. In this paper, thermodynamic optimization analysis for this type of plant (with backpressure steam turbine) and its performance criteria have been developed. It has been shown that the most efficient plant, for a target stack temperature could be achieved when the gas turbine and steam cycle are designed for maximum specific net work and cycle efficiency respectively. For validation purpose, some standard market gas turbines, which have maximum of 6% error with the basic thermodynamic model, have been chosen in this study. Also it has been shown that the results of optimization of cogeneration systems are in good agreement with those of standard turbines.
Fast Pyrolysis Oil for Power Generation
Authors: Chiaramonti David , Oasmaa Anja , Solantausta Yrjo¨
Published: September 2008

Biomass fast-pyrolysis oil (PO) is a liquid biofuel derived from lignocellulosic biomass: it offers several advantages compared to the direct us of solid bio fuels, such as high energy density, storability and transportability typical of liquid fuels, possibility to use the fuel in engines and turbines, easier downscaling of plants (which is a very important aspect for decentralized energy generation schemes). In addition, PO is the lowest cost biofuel, thus offering the possibility to penetrate also the large scale power generation market. Biomass POs have been studied and applications tested for many years, either for heat generation in medium-scale boilers or power generation. The present works reviews and analyses the most relevant experiences carried out so far and published results in power production from biomass PO. Power generation systems (PGS) which are here examined are gas turbines, diesel engines, stirling engines, as well as co-firing applications in large scale power plants (coal or natural gas plants). The main techniques for upgrading this biofuel and their impact on technologies are also shortly introduced and considered. The current status of development for each PO-based power generation option is discussed. This review work showed that long term demonstration (either technical or economical) is however still needed, even for the most developed technologies (use of PO in modified gas turbines and cofiring in natural gas stations): projects are on going to achieve long term demonstration.
NOx Emissions of a Premixed Partially Vaporized Kerosene Spray Flame
Authors: Baessler Stefan , Mo¨sl Klaus G. , Sattelmayer Thomas
Published: September 2008

An important question for future aero-engine combustors is how partial vaporization influences the NOx emissions of spray flames. In order to address this question an experimental study of the combustion of partially vaporized kerosene/air mixtures was conducted, which assesses the influence of the degree of fuel vaporization on the NOx emissions in a wide range of equivalence ratios covering the entire lean burning regime. The tests were performed at atmospheric pressure, inlet air temperatures of 313 to 376K, a reference mean air velocity of 1.35m/s, and equivalence ratios of 0.6, 0.7 and 0.9 using Jet A1 fuel. An ultrasonic atomizer was used to generate a fuel spray with a Sauter Mean Diameter of approximately 50μm. The spray and the heated air were mixed in a glass tube of 71mm diameter and a variable length of 0.5 to 1m. The temperature of the mixing air and the length of the preheater tube were used for the control of the degree of vaporization. Downstream of the vaporizing section, the mixture was ignited and the flame was stabilized with a hot wire ring that is electrically heated. For local exhaust measurements a temperature controlled suction probe in combination with a conventional gas analysis system were used. The vaporized ratio of the injected fuel was determined by a Phase Doppler Anemometer (PDA). In order to optimize the accuracy of these measurements, extensive validation tests with a patternator method were performed and a calibration curve was derived. The data collected in this study illustrates the effect of the vaporization rate Ψ upstream of the flame front on the NOx emissions, which changes with varying equivalence ratio and degree of vaporization. In the test case with low pre-vaporization, the equivalence ratio only has a minor influence on the NOx emissions. Experiments made with air preheat and higher degrees of vaporization show two effects: With increasing preheat air temperature, NOx emissions increase due to higher effective flame temperatures. However, with an increasing degree of vaporization, emissions become lower due to the dropping number and size of burning droplets, which act as hot spots. A correction for the effect of the preheat temperature was developed. It reveals the effect of the degree of pre-vaporization and shows that the NOx emissions are almost independent of Ψ for near-stoichiometric operation. At overall lean conditions the NOx emissions drop nonlinearly with Ψ. This leads to the conclusion that a high degree of vaporization is required in order to achieve substantial NOx abatement.
Experimental Study on the Heat Transfer in the Compound Cooling Passage
Authors: Li Li , Ding Shui-Ting , Xu Guo-Qiang , Tao Zhi , Deng Hong-Wu
Published: September 2008

An experimental study was carried out to comprehend the passage configuration for better the cooling effectiveness on the trailing edge of high-pressure turbine blade. Thermochromic liquid crystal technology was employed to measure the endwall temperature of the trapezoidal compound passage and the resistance coefficients of the internal ducts. It can be concluded that the configuration with suitable ejection holes in the divider wall can get higher heat transfer coefficient of the compound passage than that of the tradition configuration with a straight divider wall which form a sharp turn. This is because the spanwise impinging jets flowing through the orifices distributed at the radial orientation in the divider wall between the first passage and the second one, can improve the heat transfer of a certain low heat transfer region. Better effectiveness of heat transfer could be obtained when the straight divider wall was designed into zigzag divider wall.
Transported Scalar PDF Modeling of a Turbulent, Premixed Methane/Air Bunsen-Type Flame
Authors: Großschmidt Dirk A. , Habisreuther Peter , Bockhorn Henning
Published: September 2008

Gas turbine related combustion systems often operate under conditions, where the turbulent time scales of the flow field and the chemical reaction times are of the same order of magnitude. To describe this regime of moderate and small Damko¨hler numbers, pdf-methods have become an established modeling technique with a thoroughly derived mathematical basis. In this paper a hybrid pdf/FANS method is presented. It is based on the transported pdf equation closed at the joint composition level, which is implemented into a commercial 3D CFD solver. The solution algorithm features a stochastic particle system in a Lagrangian framework. The test case under consideration is a H2-stabilized turbulent premixed methane/air flame with co-flow. The set up was investigated using optical and conventional measurement techniques. Field measurements of velocity and composition were compared against calculations with the hybrid approach. The thermo-chemistry was described by a two domain-one step kinetic scheme. This semi-global kinetics was derived for use with CFD simulations of technical applications in the context of gas turbine combustion. For the numerical calculations the mean estimates are extracted from the stochastic particle field, which contains the complete one point statistics of the species composition vector. The knowledge of the composition pdf allows an evaluation of the structure of the turbulent reaction zone at any position of the flame.
Probabilistic Analysis of Stationary Gas Turbine Secondary Air Systems
Authors: Bischoff Thomas , Voigt Matthias , Chehab Ed , Vogeler Konrad
Published: September 2008

In this paper probabilistic methods are applied to a 1D flow model of the Secondary Air System (SAS) of an industrial gas turbine. An overview of the methods applied and the results which can be provided by the probabilistic analysis is given. The paper especially deals with the problems that arise from the high number of probabilistic input parameters connected with a simulation of the Secondary Air System. To overcome these problems a fast method for the detection of nonlinear dependencies is introduced. For improvement in the development process a numerical test plan of the SAS is used to calculate response surfaces describing the system. This allows improvement of the SAS using the response surfaces instead of Monte Carlo Simulations and therefore results in a significant reduction of required flow calculations during the improvement process towards a more robust design. Furthermore this provides a possibility to judge the effects of changes in the input parameters without additional flow calculations.
CMSX-486® Single Crystal Alloy: Production Experience and Development of an Improved Version
Authors: Wahl Jacqueline B. , Harris Ken
Published: September 2008

Modern turbine engine performance and life cycle requirements demand single crystal (SX) superalloy turbine airfoil and seal components. However, complex SX components, such as vane segments, can result in severe manufacturing cost challenges due to low manufacturing yield. These requirements led to the development of CMSX-486® alloy, a grain boundary strengthened SX superalloy with improved creep-rupture strength over SX CM 186 LC® alloy. CMSX-486 alloy has excellent casting yield achieved through generous grain inspection criteria and is used as-cast, which minimizes post-cast processing costs and eliminates the risk of recrystallization during solution heat treatment. CMSX-486 alloy has attained production status and further improvements to the alloy are under evaluation. This paper will review the unique properties which make this alloy of serious interest, with particular attention to ongoing production experience. Discussion will also include direction and results of an improved oxidation resistant version of CMSX-486 alloy which is currently under development.
Shaped-Hole Film Cooling With Pulsed Secondary Flow
Authors: Ou Shichuan , Rivir Richard B.
Published: September 2008

The effects of the coolant jet pulsing frequency (PF), duty cycle (DC), and hole shape geometry on heat transfer coefficient and film effectiveness were investigated with a film hole located on a semicircular leading edge test model with an afterbody. Cylindrical and diffusion-shaped holes located at 21.5° from the stagnation line were investigated. An infrared thermography technique with a single transient test was used to determine both the heat transfer coefficient and film effectiveness. Spanwise averaged heat transfer coefficient and film effectiveness were computed from the local values for all test conditions under the same Reynolds number (Re) of 60,000 and density ratio (DR) of 1.11. A dimensionless Frossling number (Fr) was used to represent the heat transfer coefficient. The effects of duty cycles of 50%, 75%, and 100% (continuous coolant) on film effectiveness and heat transfer coefficient were investigated at coolant jet pulsing frequencies of 5 Hertz (Hz) and 10 Hertz. The duty cycle and pulsing frequency were controlled by the opening and closing time settings of two synchronized pulsed valves. The blowing parameters investigated included continuous coolant at the blowing ratios (M) of 0.75, 1.00, 1.50 and 2.00. The subsequent pulsed cases for a combination of pulsing frequency and duty cycle were varied from the corresponding continuous case without changing the coolant flow rate (or blowing ratio) setting for a total of 40 cases for the shaped and cylindrical film holes. The shaped hole provides higher local film effectiveness values than the classical cylindrical hole when coolant flow is steady at M = 1.00. The higher local film effectiveness for the shaped hole was also observed for pulsed cases at M = 1.50 (Meff = 1.25) and M = 2.00 (Meff = 1.07) due to wider film spreading or coverage. The pulsed coolant cases provide higher spanwise averaged film effectiveness than the continuous coolant at M = 1.50 for both hole geometries. In contrast to the film effectiveness, the spanwise averaged Frossling numbers of pulsed coolant are lower compared to the continuous coolant for both hole shapes at the same blowing ratio. Combining the effects of heat transfer coefficient and film effectiveness, one can compute a relative heat load ratio to evaluate the performance of the film cooling. The pulsed coolant cases in general perform better than continuous coolant. The shaped hole geometry provides better film cooling performance than the cylindrical hole geometry for all blowing ratios including the continuous and the pulsed coolant cases studied.
7H™ Combustion System Performance With Fuel Moisturization
Authors: Feigl Markus , Myers Geoff , Thomas Stephen R. , Smith Raub
Published: September 2008

This paper describes the concept and benefits of the fuel moisturization system for the GE H System™ steam-cooled industrial gas turbine. The DLN2.5H combustion system and fuel moisturization system are both described, along with the influence of fuel moisture on combustor performance as measured during full-scale, full-pressure rig testing of the DLN2.5H combustion system. The lean, premixed DLN2.5H combustion system was targeted to deliver single-digit NOx and CO emissions from 40% to 100% combined cycle load in both the Frame 7H (60 Hz) and Frame 9H (50 Hz) heavy-duty industrial gas turbines. These machines are also designed to yield a potential combined-cycle efficiency of 60 percent or higher. Fuel moisturization contributes to the attainment of both the NOx and the combined-cycle efficiency performance goals, as discussed in this paper.
Gas Turbine Inlet Fogging System Tuning: Operator Point of View
Authors: Hain Y. , Litinetski V.
Published: September 2008

High-pressure water fogging is a relatively new technique for gas turbine inlet air cooling. Nevertheless, up to now, several hundreds of fogging systems have been installed around the world and this figure is rapidly growing. A large number of the fogging installations provided sufficient experience to establish a general approach to design, operation and maintenance of such systems. However, a fogging system could require some tuning to a specific gas turbine configuration and site conditions. Israel Electric Corporation (IEC) has implemented fourteen fogging systems on 120–150 MW gas turbines, and each system was tuned to provide higher effectiveness. Several systems were basically modified in order to reduce the risk of compressor blade erosion. Subsequent field tests had shown that the goals of the system modification and tuning were successfully achieved. This allowed extending operational hours of the fogging systems and provided noticeable fuel savings. Moreover, during the summer 2005 the fogging systems helped to achieve the all-time high peak of electricity demand. Extended use of the fogging systems features a prolonged operation at partial cooling capacity and at varying ambient temperature, pressure and humidity. This required a thorough evaluation of the fogging systems performance, in order to provide the systems settings that would allow the most effective operation with minimal risk of damage to gas turbine components, mainly the compressor blades. The paper describes an approach and results of the fogging system performance evaluation at the different operational conditions. The method allows for the rate of compressor airflow as a function of the injected water flow rate as well as of ambient pressure, temperature and humidity. Actual operational limitations are also considered. The results are illustrated with the examples that correspond to real fogging systems operating under Israeli weather conditions. The method is general and, therefore, is applicable to other weather conditions and for different fogging systems.
Response of a Rod Stabilized, Premixed Flame to Longitudinal Acoustic Forcing
Authors: Shanbhogue Santosh J. , Lieuwen Tim C.
Published: September 2008

This paper describes an experimental investigation of the flame sheet dynamics of an acoustically forced bluff body flame over a range of perturbation frequencies and amplitudes. When acoustically excited, the flame sheet displays well defined, periodic corrugations, presumably due to flame sheet perturbations created at its attachment point that convect downstream, as well as the rollup of shear layer instabilities into large scale coherent structures. The dynamics of the flame front response, such as its growth and decay in the bluff body wake, disturbance convection velocity, sub-harmonic response, and total flame area is discussed.
Turbine Stator Well Heat Transfer and Cooling Flow Optimisation
Authors: Dixon Jeffrey A. , Brunton Ivan L. , Scanlon Timothy J. , Wojciechowski Grzegorz , Stefanis Vassilis , Childs Peter R. N.
Published: September 2008

CFD methods are increasingly being used in gas turbine secondary flow system analysis and design to establish flow distribution and convective heat transfer in internal cavities. A key area of concern is the complex flows adjacent to turbine disc rims, where undesirable levels of hot annulus gas would be ingested were it not for the cooling air supplied to limit its effects on disc rim and blade fixing temperature levels. This paper presents results from a study to investigate the practicality of applying this method to the flow distribution and heat transfer in the disc rim sealing cavity between two adjacent turbine stages, referred to here as a turbine stator well. Also described is the test facility designed to validate the CFD analysis and some preliminary results from comparisons of 3D flow solutions, with measured test data.
Applications of Neural Networks to the Real-Time Prediction of Metal Temperatures in Gas Turbine Engine Components
Authors: Widrich Michael , Sinha Alok , Suarez Eva , Cassenti Brice
Published: September 2008

Several methods for predicting metal temperatures in a turbine engine are presented. Proper Orthogonal Decomposition (POD) is used to determine the system modes from temperature data sets from an engine mission. The coefficients of the system POD modes are used to identify the system dynamics. The linear state space model in conjunction with a multi-layer feedforward neural network is shown to produce superior prediction values for untrained temperature data when compared to those values produced by the state space model alone.
Enhancement of Film Cooling Performance at the Leading Edge of Turbine Blade
Authors: Kim K.-S. , Kim Youn J. , Kim S.-M.
Published: September 2008

To enhance the film cooling performance in the vicinity of the turbine blade leading edge, the flow characteristics of the film-cooled turbine blade have been investigated using a cylindrical body model. The inclination of the cooling holes is along the radius of the cylindrical wall and 20 deg relative to the spanwise direction. Mainstream Reynolds number based on the cylinder diameter was 1.01×105 and 0.69×105, and the mainstream turbulence intensities were about 0.2% in both Reynolds numbers. CO2 was used as coolant to simulate the effect of density ratio of coolant-to-mainstream. Furthermore, the effect of coolant flow rates was studied for various blowing ratios of 0.4, 0.7, 1.1, and 1.4, respectively. In experiment, spatially-resolved temperature distributions along the cylindrical body surface were visualized using infrared thermography (IRT) in conjunction with thermocouples, digital image processing, and in situ calibration procedures. This comparison shows the results generated to be reasonable and physically meaningful. The film cooling effectiveness of current measurement (0.29 mm × 0.33 min per pixel) presents high spatial and temperature resolutions compared to other studies. Results show that the blowing ratio has a strong effect on film cooling effectiveness and the coolant trajectory is sensitive to the blowing ratio. The local spanwise-averaged effectiveness can be improved by locating the first-row holes near the second-row holes.
Numerical Study of a Rotating Blade Platform With Film Cooling From Cavity Purge Flow in a 1-1/2 Turbine Stage
Authors: Yang Huitao , Chen Hamn-Ching , Han Je-Chin
Published: September 2008

Numerical simulations were performed to predict the effect of cavity purge flow on the rotating blade platform in a 1-1/2 turbine stage using a Reynolds stress turbulence model together with a non-equilibrium wall function. Simulations were carried out with a sliding mesh for the rotor under three rotating speeds (2000, 2550 and 3000 rpm) and three purge-to-mainstream mass flow ratios (0.5%, 1% and 1.5%) to investigate the effects of rotating speed and coolant purging rate on the rotating blade platform film cooling. The adiabatic film cooling effectiveness was evaluated using the adiabatic wall temperatures with and without coolant purging to examine the true effect of coolant protection. The film cooling effectiveness increases with increasing coolant purging flow ratio from 0.5% to 1.5% of mainstream. Higher rotating speed also enhances film cooling effectiveness for the range of rotating speed considered. The predicted laterally averaged adiabatic film cooling effectiveness is in good agreement with the corresponding experiment data except for the platform leading edge region. However, the detailed effectiveness distribution on the platform is not well predicted by this study. In addition, the detailed instantaneous film cooling effectiveness and the associated heat transfer coefficients for four different time phases are also reported.
Experimental and Numerical Studies of Ethanol Flames
Authors: Saxena Priyank , Williams Forman A.
Published: September 2008

This paper reports results of experimental and numerical investigations of ethanol-air diffusion flames and partially premixed flames at an air-side strain rate of 100 s−1, in a counterflow geometry. The diffusion flame consists of prevaporized fuel, with mole fraction of 0.3, diluted with nitrogen in the fuel stream, and plant air as the oxidizer stream. The partially premixed flame includes prevaporized fuel in air partially premixed to an equivalence ratio of 2.3 in the fuel stream, and plant air as the oxidizer stream. Temperature profiles were measured by thermocouple, and concentration profiles of the stable species C2H5OH, CO, CO2, H2, H2O, O2, N2, CH4, C2H6, and C2H2+C2H4 were measured by gas chromatography of samples withdrawn by a fine probe. Computational studies involved numerical integration of the conservation equations, with detailed chemistry, transport and radiation effects included, to calculate the structures of the counterflow flames. A chemical-kinetic mechanism consisting of 235 elementary steps and 46 species with recently published reaction-rate parameters was developed and tested for these flames. The proposed mechanism, which produces reasonable agreement with previous measurements of ignition, freely propagating premixed flames and diffusion-flame extinction, also yields good agreement with much of the present data, although there are quite noticeable differences between predicted and measured peak C2H6 concentrations. These differences and the desirability of additional tests of other predictions and of tests under other conditions motivate further research.