bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Heat Transfer Measurement Techniques on a Transonic Turbine Blade Tip
Authors: O’Dowd Devin , Zhang Qiang , Ligrani Phil , He Li , Friedrichs Stefan
Published: February 2010

The present study considers spatially-resolved surface heat transfer coefficients and adiabatic wall temperatures on a turbine blade tip in a linear cascade under transonic conditions. Six different measurement and processing techniques are considered and compared, including transient infrared thermography and thin-film heat flux gauges. Three methods use the same experimental setup, using a heater mesh to provide a near-instantaneous step-change in mainstream temperature, employing an infrared camera to measure surface temperature. The three methods use the same data but different processing techniques to determine the heat transfer coefficients and adiabatic wall temperatures. Two methods use different processing techniques to reconstruct heat flux from the temperature time trace measured. A plot of the heat flux versus temperature is used to determine the heat transfer coefficients and adiabatic wall temperatures. The third uses the classical solution to the 1-D non-steady Fourier equation to determine heat transfer coefficients and adiabatic wall temperatures. A fourth method uses regression analysis to calculate detailed heat transfer coefficients for a quasi-steady state condition using a thin-foil heater on the tip surface. The fifth method uses the infrared camera to measure the adiabatic wall temperature surface distribution of a blade tip after a quasi-steady state condition is present. Finally, the sixth method employs thin-film gauges to measure surface temperature histories at four discreet blade tip locations. With this approach, heat flux reconstruction is used to calculate the transient heat transfer coefficients and adiabatic wall temperatures. Overall, the present study shows that the infrared thermography technique with heat flux reconstruction using the Impulse method, is the most accurate and reliable method to obtain detailed, spatially-resolved heat transfer coefficients and adiabatic wall temperatures on a turbine blade tip in a linear cascade.
LES of Turbulent Swirling Jets: Study of Jet Precession, Recirculation and Vortex Breakdown
Authors: Dinesh Ranga , Jenkins Karl , Kirkpatrick Michael
Published: February 2010

Large eddy simulations (LES) of turbulent isothermal swirling flows have been investigated. The Sydney swirl burner configuration has been used for all simulated test cases from a low to a high swirl and Reynolds numbers. Four test cases based on different swirl numbers have been considered and the influence of the swirl number for producing recirculation, vortex breakdown, precession vortex core and the precession frequencies have been investigated. The governing equations for the continuity and momentum are solved on a structured Cartesian grid, and a Smagorinsky eddy viscosity model with the localised dynamic procedure is used as the subgrid scale turbulence model. The results show that the LES successfully predicts both the upstream first recirculation zone generated by the bluff body and the downstream vortex breakdown bubble (VBB) induced by swirl. The plots reveal that the expansion of the upstream recirculation zone is almost similar for each test case. LES results revealed that the increasing swirl number affect to form the VBB in the downstream region, however it promotes the shear layer instability in the recirculation zones. The frequency spectrums indicate the presence of low frequency oscillations and the existence of a central jet precession. Results demonstrated distinct precession frequencies at the considered spatial jet locator and agreed well with the experimental values. The results also highlight the formation of a precessing vortex core (PVC).
Requirements for Gas Turbine Inlet Systems in Russia
Authors: Nigmatulin Tagir R. , Mikhailov Vladimir E.
Published: February 2010

Russian power generation, oil and gas businesses are rapidly growing. Installation of new industrial gas turbines is booming to fulfill the demand from economic growth. Russia is a unique country from the annual temperature variation point of view. Some regions may reach up to 100C. One of the biggest challenges for world producers of gas turbines in Russia is the ability to operate products at power plants during cold winters, when ambient temperature might be −60C for a couple of weeks in a row. The reliability and availability of the equipment during the cold season is very critical. Design of inlet systems and filter houses for the Russian market, specifically for northern regions, has a lot of specifics and engineering challenges. Joint Stock Company CKTI is the biggest Russian supplier of air intake systems for industrial gas turbines and axial-flow compressors. In 1969 this enterprise designed and installed the first inlet for the power plant Dagskaya GRES (State Regional Electric Power Plant) with the first 100MW gas-turbine which was designed and manufactured by LMZ. Since the late 1960s CKTI has designed and manufactured inlet systems for the world market and been the main supplier for the Russian market. During the last two years CKTI has designed inlet systems for a broad variety of gas turbine engines ranging from 24MW up to 110MW turbines which are used for power generation and as a mechanical drive for the oil and gas industry. CKTI inlet systems with filtering devices or houses are successfully used in different climate zones including the world’s coldest city Yakutsk and hot Nigeria. CKTI has established CTQs (Critical to quality) and requirements for industrial gas turbine inlet systems which will be installed in Russia in different climate zones for all types of energy installations. The last NPI project of the inlet system, including a nonstandard layout, was done for a small gas-turbine engine which is installed on a railway cart. This arrangement is designed to clean railway lines with the exhaust jet in a quarry during the winter. The design of the inlet system with efficient multistage compressor extraction for deicing, dust and snow resistance has an interesting solution. The detailed description of challenges, weather requirements, calculations, losses, and design methodologies to qualify the system for tough requirements, are described in the paper.
Combined Unsteady Effects of Hot Streak and Trailing Edge Coolant Ejection in a Turbine Stage
Authors: An Bai-Tao , Liu Jian-Jun , Jiang Hong-De
Published: February 2010

This paper presents a 3D unsteady flow and heat transfer analysis on the first stage turbine of a heavy duty gas turbine. Attention is focused on the combined unsteady effects and the unsteady interaction mechanism of hot streak and vane trailing edge coolant ejection. The turbine stage inlet hot streak has a temperature ratio of 1.23 and six clocking position variations. Three kinds of vane trailing edge configurations are computed and compared. The first is without slot, the second is a center-line slot, and the third is a cut-back slot. The both slots are spanwise clean ones. The temperature ratio of trailing edge coolant to inlet main flow is 0.57. The mass flow ratio of trailing edge coolant to inlet main flow is 3%. The two kinds of trailing edge slots have the same inflow boundary conditions. Results show that the combination of hot streak and trailing edge coolant ejection slightly enlarges the fluctuation range of the transient averaged heat load on blade pressure surface. And the trailing edge coolant ejection significantly decreases the transient averaged heat load on blade suction surface compared with the cases without trailing edge slot. However, the trailing edge coolant ejection enhances the local heat load on blade suction surface by complex flow interaction, especially trailing edge coolant ejection combining with the hot streak impinging the vane leading edge. In addition, trailing edge coolant ejection enlarges the fluctuation range of blade force greatly compared with the case without trailing edge slot. Also, the different hot streak clocking positions combining with the trailing edge coolant ejection have different behaviors and interaction mechanism. The influences of centerline slot combining with hot streak on both the transient fluctuation of heat load and blade force are greater than that of cut-back slot.
Correlating Flashback Tendencies for Premixed Injection of Hydrogen and Methane Mixtures at Elevated Temperature and Pressure
Authors: Wang Qing , McDonell Vincent , Steinthorsson Erlendur , Mansour Adel , Hollon Brian
Published: February 2010

Flashback is a critical operability issue for lean premixed fuel injection strategies. This is particularly true for hydrogen and high hydrogen content fuels. As a result, efficient analytical tools to help predict the occurrence of flashback would be of great value to the hardware designer. In the present work, a RANS based CFD strategy is used in conjunction with analytical expressions for determining flashback likelihood. The approach uses local flow properties combined with 1 D models to establish a flashback propensity factor that can be used to screen designs. Peclet number based models are also considered. The methods are applied to one micromixer configuration for a variety flow rates, pressures, equivalence ratios, and temperatures. The micromixing injector is a small premixing cup with multiple fuel injection sites in close proximity to air inlets to produce rapid mixing between fuel and air, with an axial core flow that is intended to prevent ingress of flame into the injector. The results illustrate the effectiveness of the approach for screening for flashback for the premixer studied over the range of conditions studied. The analysis suggests that, for the current test hardware, the critical ingress pathway is via boundary layer propagation. Further, the approach successfully provides a qualitative indication of whether ingress can be expected for a given condition.
Assessment of a Set of Numerical Tools for the Design of Aero-Engines Combustors: Study of a Tubular Test Rig
Authors: Andreini A. , Ceccherini A. , Facchini B. , Turrini F. , Vitale I.
Published: February 2010

This paper reports the numerical study performed during the setup of a tubular laboratory combustor developed by Avio Group. The main purpose of this study is the assessment of some numerical tools which might be employed for the design of aero-engines combustors. Adopted methodologies pertains with heat transfer and exhaust emissions issues of combustor design, and they refer to both detailed three dimensional and simplified zero/one dimensional formulations. An exhaustive discussion about the obtained result and about the adopted modelling criteria is reported in the paper. The rig has a tubular geometry that allows to study the single burner of a typical annular combustor of jet engines. Considered operating condition for the tests refers to Max Take-Off (ICAO 100%) in the cycle of a typical jet engine. Three different numerical tools were considered, representing the fundamental steps during the preliminary and detailed design of combustors. The first one is a 1D procedure capable to analyze the cooling flow network of the combustor and to predict liner wall temperature and heat loads. The second is a classical chemical reactor network code for flame temperature and exhaust emissions prediction. Such preliminary design tools are usually supported by reactive CFD computations. In this work both two dimensional and three dimensional CFD models are considered with different goals. A 2D CFD model of flame tube with prescribed mass flow rates allows to quickly test various turbulence, combustion and emissions models, while a 3D model of the complete hardware (liner, burner and cooling network), permits to predict air flow splits and wall radiative and convective heat loads. Furthermore a final 3D reactive CFD computation with radiation conjugated with the thermal conduction solution across the liner, permits to estimate the wall temperature distribution. The whole set of numerical results has pointed out an appreciable agreement among the various tools representing a valid assessment of the validity and robustness of selected design methodologies. A more significant validation of codes accuracy will be possible as soon as the scheduled experimental results will be available.
Engine Conceptual Design Studies for a Hybrid Wing Body Aircraft
Authors: Tong Michael , Jones Scott M. , Haller William J. , Handschuh Robert F.
Published: February 2010

Worldwide concerns of air quality and climate change have made environmental protection one of the most critical issues in aviation today. NASA’s current Fundamental Aeronautics research program is directed at three generations of aircraft in the near, mid and far term, with initial operating capability around 2015, 2020, and 2030, respectively. Each generation has associated goals for fuel burn, NOx, noise, and field-length reductions relative to today’s aircrafts. The research for the 2020 generation is directed at enabling a hybrid wing body (HWB) aircraft to meet NASA’s aggressive technology goals. This paper presents the conceptual cycle and mechanical designs of the two engine concepts, podded and embedded systems, which were proposed for a HWB cargo freighter. They are expected to offer significant benefits in noise reductions without compromising the fuel burn.
Compensation of Intake Induced Flow Non-Uniformities With Compressor Blade Lean Angle Changes
Authors: Templalexis Ioannis , Pachidis Vassilios , Kotsiopoulos Petros
Published: February 2010

The compression system has traditionally drawn most of the attention concerning the gas turbine engine performance assessment and design procedure. It is the most vulnerable component to flow fluctuations within a gas turbine engine. In particular this study focuses on performance deviations, between an installed and an uninstalled compressor. Test results acquired from a test bed installation will differ from these recorded when the compressor operates as an integral part of the engine. The upstream duct, whether an intake or an interstage duct, will affect the flow field pattern ingested into the compressor. The case studies presented into this work aim to mostly qualify the effect of boundary layer growth along the upstream duct walls, upon compressor performance. Additionally, compressor performance response on blade lean angle variation is being addressed, with the aim of acquiring an understanding as to how compressor blade lean angle changes interact with intake induced flow non uniformities. Such studies are usually conducted during the preliminary design stage, before the compressor is built. Consequently, experimental performance investigation is excluded at this stage of development. Computer aided simulation techniques are between the few if not the only option for compressor performance prediction. Given the fact that many such design parameters need to be assessed under the time pressure exerted by the tight compressor development program, the compressor flow simulation technique used needs to provide reliable results while consuming the least possible computational time. Such a low computational time compressor flow simulation method, among others, is the two dimensional (2D) streamline curvature (SLC) method, being applied within the frame of reference of the current study. The paper is introduced by a brief discussion on SLC method that was proposed more than 50 years ago. Then a reference is made to the Radial Equilibrium Equation (REE) which is the mathematical basis of the code, commenting on the assumptions that were undertaken. Subsequently the influence of the intake presence on the compressor inlet radial flow distribution is being addressed, with the aim of adjusting compressor blade inlet lean angle, in order to minimize compressor performance deterioration. Finally the paper is concluded with a discussion of the results.
Combined Cycles With CO2 Capture: Two Alternatives for System Integration
Authors: Sipo¨cz Nikolett , Assadi Mohsen
Published: February 2010

As Carbon Capture and Storage (CCS) technology has grown as a promising option to significantly reduce CO2 emissions, system integration and optimization claim an important and crucial role. This paper presents a comparative study of a gas turbine cycle with post-combustion CO2 separation using an amine-based absorption process with Monoethanolamine (MEA). The study has been made for a triple pressure reheated 400 MWe natural gas-fuelled combined cycle (NGCC) with exhaust gas recirculation (EGR) to improve capture efficiency. Two different options for the energy supply to the solvent regeneration have been evaluated and compared concerning plant performance. In the first alternative heat is provided by steam extracted internally from the bottoming steam cycle while in the second option an external biomass-fuelled boiler was utilized to generate the required heat. With this novel configuration the amount of CO2 captured can be even more than 100% if the exhaust gas from the bio-fuelled boiler is mixed and cleaned together with the main exhaust gas flow from the combined cycle. In order to make an unprejudiced comparison between the two alternatives, the reduced steam turbine efficiency has been taken into consideration and estimated, for the alternative with internal steam extraction. The cycles have been modelled in the commercial heat and mass balance programme IPSEpro™ using detailed component models. Utilizing EGR can double the CO2 content of the exhaust gases and reduce the energy need for the separation process by approximately 2%-points. Using an external biomass-fuelled boiler as heat source for amine regeneration, turns out to be an interesting option due to high CO2 capture effectiveness. However the electrical efficiency of the power plant is reduced compared to the option with internal steam extraction. Another drawback with the external boiler is the higher investment costs but nevertheless, it is flexibility due to the independency from the rest of the power generation system represents a major operational advantage.
Power Losses Identification on Turbocharger Hydrodynamic Bearing Systems: Test and Prediction
Authors: Lamquin Thierry , Gjika Kostandin
Published: February 2010

Design of automotive engines, with increasing focus on downsizing, high performance and low fuel emissions, provides several challenges to turbocharging technology and design. The development of a low friction rotor-bearing system is fundamental to effectively differentiate in the current environment. The exhaust gas energy from the turbine is transmitted through the bearing system to the compressor stage, and then to the engine. A lower bearing system friction allows more power to be transmitted to the compressor. This paper deals with experimental and analytical investigations for rotor-bearing system (RBS) power losses. A powerful test facility and associated experimental approach, based on the temperature drop of the gas flowing through the turbine stage, have been developed. The uncertainty due to instrumentation and process is identified as lower than 12%. The power loss related to the radial bearing is calculated analytically using the laminar Couette model; the power loss due to the axial bearing is calculated by the integration of the 2D Reynolds equation. The additional power loss between the slender shaft and inner bearing surface is calculated using a turbulent Couette model. The power loss due to the seals is not taken into account. Extensive testing in steady state condition has been completed on the test bench. Two different bearing designs with axial grooves have been tested. The influence of oil on the bearing loss has been identified by testing at two oil inlet temperatures (30 °C and 100 °C) and two oil inlet pressures (2 bars and 4 bars). The measurement and prediction of power losses are in good agreement.
Heat Transfer on a Turbocharger Under Constant Load Points
Authors: Romagnoli A. , Martinez-Botas Ricardo
Published: February 2010

The processes occurring in turbo machinery applications are frequently treated as adiabatic. However, in a turbocharger significant heat transfer occurs, leading to a deficit of turbocharger performance. The overall objective of this experimental work is to improve the understanding of the heat transfer process taking place in a turbocharger when installed on an internal combustion engine. In order to do this, beyond the standard set of measurements needed to define the turbo operating point, a large number of thermocouples were installed on the turbocharger. The tests results allow the quantification of the temperatures within the turbocharger and revealed that a nonuniform temperature distribution exists on the compressor and turbine casings. This is partly attributed to the proximity of the turbocharger to the engine. This process plays a role on the deterioration of the compressor efficiency when compared to the corresponding adiabatic efficiency. A correlation that allows the calculation of the compressor exit temperature is proposed. The method uses the surface temperature of the bearing housing; it was validated against experimental data with deviations no larger than 3%. A simplified 1-dimensional heat transfer model was also developed and compared with experimental measurements. The algorithms calculate the heat transferred through the turbocharger, from the hot end to the cold end by means of lump masses. The compressor performance deterioration from the adiabatic map is predicted.
Gas Turbines and Biodiesel: A Clarification of the Relative NOX Indices of FAME, Gasoil, and Natural Gas
Authors: Glaude Pierre A. , Fournet Rene´ , Bounaceur Roda , Moliere Michel
Published: February 2010

There is currently a sustained interest in biofuels as they represent a potential alternative to petroleum derived fuels. Biofuels are likely to help decrease greenhouse gases emissions and the dependence on oil resources. Biodiesels are Fatty Acid Methyl Esters (FAMEs) that are mainly derived from vegetable oils; their compositions depend from the parent vegetables: rapeseed (“RME”), soybean (“SME”), sunflower, palm etc. A fraction of biodiesel has also an animal origin (“tallow”). A key factor for the use of biofuels in gas turbines is their Emissions Indices (NOx, CO, VOC, PM) in comparison with those of conventional “petroleum gasoils”. While biodiesels reduce carbon-containing pollutants, experimental data from diesel engines show a slight increase in NOx. The literature relating to gas turbines is very scarce. Two recent, independent field tests carried out in Europe (RME) and in the USA (SME) showed slightly lower NOx while a lab test on a microturbine showed the opposite effect. To clarify the NOx index of biodiesels in gas turbines, a study has been undertaken, taking gasoil and natural gas (NG) as reference fuels. In this study, a calculation of the flame temperature developed by the 3 classes of fuels has been performed and the effect of their respective compositions has been investigated. The five FAMEs studied were RME, SME and methyl esters of sunflower, palm and tallow; these are representative of most widespread vegetable and animal oil bases worldwide. The software THERGAS has been used to calculate the enthalpy and free energy properties of the fuels and GASEQ for the flame temperature (Tf), acknowledging the fact that “thermal NOx” represents the predominant form of NOx in gas turbines. To complete the approach to structural effects, we have modeled two NG compositions (rich and weak gas) and three types of gasoil using variable blends of eleven linear/branched/cyclic molecules. The results are consistent with the two recent field tests and show that the FAMEs lie close to petroleum gasoils and higher than NG in terms of NOx emission. The composition of the biodiesel and regular diesel fuel influences their combustion heat: methyl esters with double bonds see a slight increase of their Tf and their NOx index while that of gasoil is sensitive to the aromatic content.
CMSX-486® Alloy Update
Authors: Wahl Jacqueline , Harris Ken
Published: February 2010

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. As presented at TURBO EXPO 2002 and 2006, 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. This paper will review the unique properties that make this alloy desirable, with particular attention to ongoing developments. Significant market interest has resulted in additional property evaluation, including strain-controlled low cycle fatigue testing which has produced fatigue lives similar to HIP’ed and solutioned CMSX-4® SX alloy at 1038°C. This was surprising considering the non-homogeneous microstructure of CMSX-486 alloy, which is used in the as-cast + double aged heat treat condition. Also, burner rig dynamic, cyclic oxidation and Type I hot corrosion results will be presented for CMSX-486 (SLS) [La+Y] alloy in comparison to CMSX-4, CMSX-4(SLS)[La+Y] and CMSX-486 alloys. Scanning electron microscopy analysis shows residual sulfur and phosphorus in CMSX-486 (SLS) [La+Y] are tied up as Y and La carbo-sulfides and phosphides.
An Experimental Study of Sprays in Cross Flow Representative of Gas Turbine Engine Secondary Air Systems
Authors: Regan N. J. , Atkins N. R. , Long C. A. , Childs P. R. N. , Hutcheson P. S. , Hart K. J.
Published: February 2010

The flow in the secondary air system of a gas turbine engine passes over numerous oil supply and scavenge pipes and a fracture in such a pipe will cause a jet of oil to be ejected as a spray. This spray will disperse in the surrounding flow. Accurate and reliable numerical modelling of these sprays presents significant problems due in part to their complexity, but also the lack of experimental data available for model validation. This paper describes the design, manufacture, testing and results from an experimental test rig aimed at spray characterisation. The sprays considered were produced through a round sharp edged nozzle with a 0.57 mm diameter and a length to diameter ratio of 1.61. The spray was introduced normal to the cross flow. Phase Doppler Anemometry was used to determine droplet size and velocity for Weber numbers within the range of 13 < Weg < 580 and Momentum Flux Ratio within the range of 0.8 < q < 136, resulting in 19 different spray fields. Each of these spray fields has been characterised at three axial locations. Contours of droplet size, mass flux distribution, axial droplet velocity and transverse droplet velocity are presented. In addition, a pulsed laser sheet and CCD camera were used to analyse the jet behaviour in terms of break up length and jet trajectory.
The Effect of Partial Admission on Multistage Radial Inflow Industrial Steam Turbine
Authors: Li Yijin , Zheng Qun , Sun Lanxin
Published: February 2010

Aerodynamic performances of a partial admission multistage radial inflow turbine are investigated with numerical simulation. A three-dimensional unsteady Reynolds-averaged Navier–Stokes solver closed by Baldwin-Lomax model is applied for the computations. The flow field features of the first stages with partial admission are analyzed and discussed. Detailed flow patterns of the partial admission radial turbine impeller are presented here in this paper.
Prediction of Aerodynamic Frequencies in a Gas Turbine Combustor Using Transient CFD
Authors: Bulat Ghenadie , Stopford Phil , Turrell Mark , Frach Dawid , Buchanan Eoghan , Sto¨hr Michael
Published: February 2010

This paper presents the results of a transient CFD analysis of the entire combustion system and the 1st row of nozzle guide vanes of a small gas turbine combustor. The focus of the investigation is the fluid dynamics within the combustor casing and its impact on combustor internal flows. Full-scale compressible transient CFD computations of a single combustor can of a Siemens gas turbine were performed. The casing flow of a 1/6th sector of the engine, corresponding to a single can was also simulated. Time dependent analyses of the combusting flow were performed for each case and the main features compared. In particular the main aerodynamic structures, such as vortex shedding and the Precessing Vortex Core (PVC), were characterised. A comparison was also made with non-combusting calculations to determine the effect of combustion. This work has taken the advantage of improvements in capabilities of numerical methods and computational power to develop design tools for gas turbine combustion systems. The work presented here is the first application of an improved turbulence model with the compressible solver in a gas turbine combustion system. This allows small scales of transient features to be captured. In addition, the presented work is the first simulation coupling the combustor aerodynamics to the casing flows.
Effects of Biot Number on Temperature and Heat-Flux Distributions in a TBC-Coated Flat Plate Cooled by Rib-Enhanced Internal Cooling
Authors: Shih T. I.-P. , Chi X. , Bryden K. M. , Alsup C. , Dennis R. A.
Published: February 2010

Advanced turbines are designed to operate at near the material’s maximum allowable temperature. Thus, there is very little room for mistakes in the design of cooling strategies. Since the heat-transfer coefficient varies significantly about ribs and pin fins in internal-cooling passages, different parts of the turbine material exposed to the hot gas are cooled at different rates by internal cooling, and this could produce substantial temperature variations within the material, including hot spots. For a given hot-gas temperature and a given coolant temperature, the amount of temperature variation within the material depends on the Biot number. In this study, conjugate heat-transfer analysis were performed to investigate the effects of Biot number on the temperature and heat flux in a TBC-coated flat plate exposed to hot gas on one side and rib-enhanced internal cooling on the other side. The Biot numbers (Bi) examined range from 0.4 to 6 if the length scale in Bi is based on the thickness of the TBC-coated plate (L) and 0.2 to 3 if based on L/2. This computational study uses 3-D steady RANS closed by the realizable k-ε turbulence model for the gas phase (wall functions not used) and the Fourier law for the solid phase. Results obtained show that for two geometrically similar TBC-coated plates exposed to the same hot-gas and coolant temperatures, if Bi is nearly the same, then the magnitude of the temperature will be nearly the same and contours of the temperatures will be nearly geometrically similar. The contours of heat flux, however, will be geometrically similar but have very different magnitudes because the gradients are different. Also, though the variations in temperature from the hot-gas to the coolant side of the TBC-coated plate decrease with decreasing Bi, the variation in temperature in the spanwise direction can actually increase with decreasing Bi. When the Bi based on L is between 0.4 to 1, that temperature variation in the super alloy next to the TBC can differ by as much as 25 K along the spanwise direction because of the large variations in the local heat-transfer coefficients induced by the ribs in the spanwise direction.
Refinement of Water Droplets With Surfactants for Wet Compression of Gas Turbine
Authors: Zhu Rongkai , Zheng Qun , Yue Guoqiang , Bhargava Rakesh
Published: February 2010

Concerned with the influence of the size of water droplets on the effect of wet compression, it is important to control the size of water droplets among 5–10 microns or smaller, for this purpose an experimental work is carried out by improve the surface behavior of water aiming to reduce its surface tension. Non-ionic surfactants and its combination were employed to reach such an aim. The surface tension of water was reduced from 72.9mN/m to 41.2mN/m or even lower depending on the cost. It offers a possible way to refine spray, and ready to use in wet compression process.
Development of Key Technologies for the Next Generation 1700C-Class Gas Turbine
Authors: Ito Eisaku , Okada Ikuo , Tsukagoshi Keizo , Muyama Akimasa , Masada Junichiro
Published: February 2010

In order to prevent global warming, the amount of CO2 produced by fossil fuel power plants needed to be reduced. In such an environment, improvement of the gas turbine thermal efficiency for GTCC is essential. Mitsubishi Heavy Industries, Ltd. is a participant in a national project aimed at developing 1700°C gas turbine technology. As part of this national project, selected component technologies are investigated in detail.
Jet Impingement and Forced Convection Cooling Experimental Study in Rotating Turbine Blades
Authors: Chiang Hsiao-Wei D. , Li Hsin-Lung
Published: February 2010

Both jet impingement and forced convection are attractive cooling mechanisms and have been widely used in cooling of gas turbine blades. Convective heat transfer from impinging jets is known to yield high local and area averaged heat transfer coefficients. Impingement jets are of particular interest in the cooling of gas turbine components where advancement relies on the ability to dissipate extremely large heat loads. The current research is concerned with the measurement and comparison of both jet impingement and forced convection heat transfer in the Reynolds number range of 10,000 to 30,000. The present study is aimed at experimentally testing two different setups with forced convection and jet impingement in rotating turbine blades up to 700 rpm. This research also focused on to observe how Coriolis forces and impingement cooling inside the passage in rotating conditions within a cooling passage. Local heat transfer coefficients are obtained for each test section through thermal-couple technique with slip rings. The cross section of the passage is 10 mm × 10 mm without ribs. The surface heating condition has a uniform heat flux enforced. The forced convection cooling effects were studied using serpentine passages with three corner turns under different rotating speeds and different inlet Reynolds numbers. The impingement cooling study uses a straight passage with a single jet hole under different Reynolds numbers of the impingement flow and the cross flow. In summary, the main purpose is to study the rotation effects on both the jet impingement and the serpentine convection cooling types. Our study shows that rotation effects increase the serpentine cooling and, on the other hand, reduce the jet impingement cooling.
An Experimental Investigation of Showerhead Film Cooling Performance in a Transonic Vane Cascade at Low and High Freestream Turbulence
Authors: Bolchoz T. , Nasir S. , Reagle C. , Ng W. , Moon H. K.
Published: February 2010

This experiment investigates the effects of blowing ratio on the film cooling performance of a showerhead-cooled first-stage turbine vane at low freestream turbulence (Tu = 2%) and an integral length scale normalized by vane pitch (Λx/P) of 0.05. The exit Reynolds number based on vane true chord is 1.1 × 106. The effect of freestream turbulence at high Mach number (Mex = 0.76) and blowing ratio (BR = 0, 1.5, 2.0) is also explored by comparing results with high freestream turbulence measurements (Tu = 16%) previously performed in the same cascade. To characterize film cooling performance, platinum thin-film gauges were used to measure Nusselt number and film cooling effectiveness distributions at the midspan of the vane. Net heat flux reduction is also addressed. The primary effects of coolant injection were augmentation of Nusselt number and reduction of adiabatic wall temperature on the vane surface. In general, increasing blowing ratio showed increases in Nusselt number augmentation over the vane surface and an increase in film cooling effectiveness as well. Both Nusselt number and film cooling effectiveness trends were influenced by a strong favorable pressure gradient and resulting flow acceleration on the suction surface. Comparing low freestream turbulence results with high freestream turbulence measurements showed that large-scale, high freestream turbulence can decrease heat transfer coefficient and film cooling effectiveness downstream of injection.
Porosity Effects on Thermo-Physical Properties of Standard and Vertically Cracked Thermal Barrier Coating Samples
Authors: Silva Monica B. , Guo S. M. , Uppu Nalini , Diwan Ravinder , Mensah Patrick F.
Published: February 2010

Yttria-Stabilized-Zirconia (YSZ) is the most common material used in the fabrication of Thermal Barrier Coatings (TBCs) for gas turbine applications. Due to the low thermal conductivity and a small mismatch of the thermal expansion coefficient to the high temperature alloy, YSZ is commonly used as the top coat layer to provide a thermal barrier effect. The aim of this work is to study the thermo-physical properties of standard (STD) and vertically cracked (VC) thermal barrier coatings fabricated by Atmospheric Plasma Spray (APS) for two different thicknesses, 400 and 600 μm respectively. This paper reports the thermal diffusivity, thermal conductivity, specific heat, porosity, and scanning electron microscope (SEM) images of STD-TBC samples and VC-TBC samples. In addition, a heat transfer model is presented for the STD-TBC and VC-TBC microstructures. The results show an increase in both thermal diffusivity and conductivity for the VC-TBC samples, compared to the STD-TBC sample over the temperature range tested (400°C to 800°C). In addition, there is a temperature dependence of the thermal diffusivity and the thermal conductivity for both VC-TBC and STD-TBC samples. The change of thermo-physical properties is directly linked to the microstructure of the samples, demonstrated by the porosity measurements, SEM images, and the heat transfer model.
Influence of Internal Cooling Configuration on Metal Temperature Distributions of Future Coal-Fuel Based Turbine Airfoils
Authors: Siw Sin Chien , Chyu Minking K. , Karaivanov Ventzislav G. , Slaughter William S. , Alvin Mary Anne
Published: February 2010

Future advanced turbine systems for electric power generation systems, based on coal-gasified fuels with CO2 capture and sequestration, are aimed for achieving higher cycle efficiency and near-zero emission. Most promising operating cycles being developed are hydrogen-fired cycle and oxy-fuel cycle. Both cycles will likely have turbine working fluids significantly different from that of conventional air-based gas turbines. In addition, the oxy-fuel cycle will have a turbine inlet temperature target at approximately 2030K (1760°C), significantly higher than the current level. This suggests that aerothermal control and cooling will play a critical role in realizing our nation’s future fossil power generation systems. This paper provides a computational analysis in comparing the internal cooling performance of a double-wall or skin-cooled airfoil to that of an equivalent serpentine-cooled airfoil. The present results reveal that the double-wall or skin cooled approach produces superior performance than the conventional serpentine designs. This is particularly effective for the oxy-fuel turbine with elevated turbine inlet temperatures. The effects of coolant-side internal heat transfer coefficient on the airfoil metal temperature in both hydrogen-fired and oxy-fuel turbines are evaluated. The contribution of thermal barrier coatings (TBC) toward overall thermal protection for turbine airfoil cooled under these two different cooling configurations is also assessed.
Large-Eddy Simulation and Passive Control of Flows for a Low Pressure Turbine Cascade
Authors: Lan Jibing , Xie Yonghui , Zhang Di , Shu Jing
Published: February 2010

A rectangular bar which just likes a forward-backward facing step was designed to passive control of the Low-Pressure Turbine (LPT) PakB cascade suction surface separation. Large-eddy simulation (LES) was adopted to analyze the separated-transition flows for the PakB cascade with and without the rectangular bar at Re (Reynolds number based on inlet condition and axial chord) of 86,000 and the freestream turbulence intensity of 1%. Computed results of uncontrolled condition agree well with the experimental data of Lake et al.[6, 7]. And the LES results shown that the rectangular bar control device was successful to control the LPT cascade suction surface separation and provides about 10% kinetic loss coefficient reduction from the uncontrolled one. Unsteady flow structures were also investigated in detail. Static pressure fluctuation frequency at six locations, ranging from 0.56Cx to 0.95Cx axial chord location and with a constant wall normal distance y/h = 1.0, was the same to the separation bubble vortex shedding frequency. Unsteady fluctuation velocity was examined too, which confirmed that the separation bubble vortex frequency was the same to the suction surface static pressure fluctuation frequency.
Proposal for a Highly Efficient Cogeneration System Using an Atmospheric Pressure Turbine Coupled With Biomass Gasification
Authors: Tsujikawa Y. , Kaneko K. , Muraoka N.
Published: February 2010

Biomass is a significant renewable energy source. The conversion of woody biomass into a combustible gas provides the opportunity to enhance the efficiency of biomass-based power systems, and allows solid fuels to be used in high-efficiency power generation processes. This paper discusses the energy efficient utilization of biomass by turbo machines under unpressurized conditions, working with the inverted Brayton cycle in which turbine expansion, cooling by heat exchanger and draft by compressor are made in an open cycle mode. We call this an “atmospheric pressure turbine (APT)”. Thermodynamic analysis has shown that an electric efficiency up to 25% (HHV) and a total energy efficiency of more than 80% (HHV) are expected for combined heat and power applications even at small plant capacities (∼40 kW).
Experimental Investigation of Thermoacoustic Oscillations in Syngas Premixed Multi-Swirler Model Combustors
Authors: Song Quanbin , Fang Aibin , Xu Gang , Xu Yanji , Huang Weiguang
Published: February 2010

This paper presents the experimental results of the thermoacoustic oscillations in several premixed syngas multi-swirler model combustors. Multi-swirler lean premixed combustion technology has been successfully applied to achieve an anticipative stability, lower noise and high efficiency in industrial gas turbines that burn natural gas or distillated oil. However, some critical operational issues, including combustion oscillations, flashback, blowout and autoignition, should be considered and balanced when burning the coal-derived syngas mainly composed of H2 and CO. In this paper several multi-swirler combustors are tested on an atmospheric-pressure downscaled test rig. Each multi-swirler combustor includes several elemental swirling nozzles with the equal Swirl Number and different array of port configurations. The dynamic pressure, dynamic heat release and critical flashback equivalence ratio are tested in these model combustors burning several kinds of simulated syngases with a similar low heat value. Firstly, the critical equivalence ratios of flashback are shown and compared with those in single-swirler combustors. Secondly, the paper presents the analysis of the temporal and spectral features of dynamic pressure oscillations using many data-processing methods. Thirdly, we describe the bifurcation and retardation phenomenon when the combustion transforms between stable and unstable operations. We also discuss how the equivalence ratio, the fuel composition and the combustor inlet velocity play important roles in determining the amplitudes, the frequencies, the bifurcation and retardation of the thermoacoustic oscillations. Finally, we use a wavelet transformation with a higher resolution in time domain than that with a PSD estimation by the AR model. The processes of amplitude “jump” and flashback are analyzed in details. The results in this paper could improve the current understanding of the nonlinear self-excited and combustion driven thermoacoustic oscillations in gas turbines and give us some references to the development of lean premixed syngas turbines for coal-based IGCC and co-generation systems.
Flowfield Investigation of a Compressor Cascade at High Incidence—Part 1: Pneumatic Probe Measurements
Authors: Zachos Pavlos K. , Pachidis Vassilios , Charnley Bernard , Pilidis Pericles
Published: February 2010

The performance prediction of axial flow compressors and turbines still relies on the stationary testing of blade cascades. Most of the blade testing studies are done for operating conditions close to the design point or in off-design areas not too far from it. However, blade performance remains unexplored at very far off-design conditions, such as windmilling, characterised by operation under extremely low mass flows and rotational speeds which, in turn, imply highly negative incidence angle values. In this paper, the flow field generated by a 3-dimensional linear compressor cascade at a highly negative incidence angle and zero rotational speed is experimentally investigated using a pneumatic miniature cobra probe. The main objective of the study is to derive the total pressure loss through the blades at such a highly negative incidence angle. An overview of the blade geometry as well as of the experimental facility is given whereas the measurement strategy and the data acquisition technique are also presented. An uncertainty study taking into account the most significant factors affecting the quality of the results has been carried out. As shown by the measurements taken at specific positions downstream of the blades, the flowfield is dominated by highly separated flows on the pressure surface, which contribute to the increased values of the total pressure loss coefficient which seems to be weakly dependent on the inlet Mach number. The quantitative measure of the pressure losses at the extremely negative incidence angle examined can be considered to be a validation platform for correspondent numerical studies of similar flow conditions. Additionally, the experimental results obtained can be used to extend the applicability of the current pressure loss models, increasing the predictive capability of the through flow numerical approaches towards far off-design areas of component or whole engine operation.
A Survey of New Technologies Used by Siemens Energy for the Monitoring and Diagnosis of a Global Fleet of Power Generation Systems
Authors: Plotts Kurt , Diatzikis Evangelos
Published: February 2010

Siemens has been on the cutting edge of the power generation business for over a century and has been providing diagnostics systems design and implementation since the early 1980s. Siemens Power Diagnostics® Services is designed to maximize plant performance, availability and profitability. Engineering knowledge, combined with the use of sophisticated tools, provides trending and analysis capabilities to address a broad range of operating needs specific to each customer. The goal of Power Diagnostics® is to enhance Siemens assistance to our customers through the detection of impending operational problems thereby helping to minimize unplanned outages and maximize power generation availability. A variety of new technologies are being harnessed to further this goal. A survey and discussion of these technologies will be the goal of this paper. Some of the projects discussed will be; Advances in the Power Plant Automated Diagnostics Systems, Blade Vibration Monitor (BVM), Fiber Optic Vibration Monitor (FOVM), and the Radio Frequency Monitor (RFM). The development and verification phases of research projects have often been conducted at customer sites. Many aspects of these technologies are new and will be of interest to gas turbine engineers as they are not widely applied yet. It is hoped that the reader will gain a new appreciation for the scope of modern diagnostic methods for power generation systems.