The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Je-chin Han - One of the best experts on this subject based on the ideXlab platform.
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Upstream Film Cooling on the Contoured Endwall of a Transonic Turbine Vane in an Annular Cascade
Volume 7B: Heat Transfer, 2020Co-Authors: Daniel A. Salinas, Je-chin Han, Lesley M. Wright, Izhar Ullah, John W. Mcclintic, Daniel C. Crites, Ardeshir RiahiAbstract:Abstract The effects of Mainstream Flow velocity, density ratio (DR), and coolant-to-Mainstream mass Flow ratio (MFR) were investigated on a vane endwall in a transonic, annular cascade. A blow down facility consisting of five vanes was used. The film cooling effectiveness was measured using binary pressure sensitive paint (BPSP). The Mainstream Flow was set using isentropic exit Mach numbers of 0.7 and 0.9. The coolant-to-Mainstream density ratio varied from 1.0 to 2.0. The coolant to Mainstream MFR varied from 0.75% to 1.25%. The endwall was cooled by eighteen discrete holes located upstream of the vane passage to provide cooling to the upstream half of the endwall. Due to the curvature of the vane endwall, the upstream holes provided uniform coverage entering the endwall passage. The coverage was effective leading to the throat of the passage, where the downstream holes could provide additional protection. Increasing the coolant Flowrate increased the effectiveness provided by the film cooling holes. Increasing the density of the coolant increases the effectiveness on the endwall while enhancing the lateral spread of the coolant. Finally, increasing the velocity of the Mainstream while holding the MFR constant also yields increased protection on the endwall. Over the range of Flow conditions considered in this study, the binary pressure sensitive paint proved to be a valuable tool for obtaining detailed pressure and film effectiveness distributions.
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Internal heat transfer of film-cooled leading edge model with normal and tangential impinging jets
International Journal of Heat and Mass Transfer, 2019Co-Authors: Mingjie Zhang, Nian Wang, Je-chin HanAbstract:Abstract This paper investigates internal heat transfer of film-cooled leading edge with Mainstream Flow. The semi-cylindrical leading edge model receives coolant through impinging jets located at the neighborhood rectangular channel. The leading edge has three rows of cylindrical film cooling holes: row 1 located along the stagnation line (0°) and rows 2 and 3 at ±40° measured from the stagnation line. All film cooling holes are at an inclined angle of 25° relatives to the surface. There are two impinging jet designs in this study: the normal jet and the tangential jet. The normal jet has one row of normal jet impinging holes. After jets impinging on the inner wall of the semi-cylinder stagnation line, coolant spreads out through film cooling holes. The tangential jet has two rows of tangential jet impinging holes. Swirl Flow is generated when jets enter the semi-cylinder from two sides of the semi-cylinder. Mainstream Reynolds number is about 100,000 based on the outside diameter of the leading edge cylinder, and the Mainstream turbulence intensity is about 7%. Leading edge detailed internal heat transfer distributions are measured by using transient liquid crystal method. Three different coolant jet Reynolds numbers are tested (Rej = 5000, 10,000 and 15,000), corresponding to averaged blowing ratios about 0.77, 1.54, and 2.31. The experimental results provide useful information for the jet impingement cooling design, especially the leading edge region is under the conditions of Mainstream Flow and external film extraction. CFD simulations are performed to present the velocity field and compare the heat transfer results with experimental data.
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Influence of Coolant Density on Turbine Blade Platform Film-Cooling
Journal of Thermal Science and Engineering Applications, 2012Co-Authors: Diganta Narzary, Kuo-chun Liu, Je-chin HanAbstract:Detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform of a five-blade linear cascade. The parameters chosen were freestream turbulence intensity, upstream stator-rotor purge Flow rate, discrete-hole film-cooling blowing ratio, and coolant-to-Mainstream density ratio. The measurement technique adopted was temperature sensitive paint (TSP) technique. Two turbulence intensities of 4.2% and 10.5%; three purge Flows between the range of 0.25% and 0.75% of Mainstream Flow rate; three blowing ratios between 1.0 and 1.8; and three density ratios between 1.1 and 2.2 were investigated. Purge Flow was supplied via a typical double-toothed stator-rotor seal, whereas the discrete-hole film-cooling was accomplished via two rows of cylindrical holes arranged along the length of the platform. The inlet and the exit Mach numbers were 0.27 and 0.44, respectively. Reynolds number of the Mainstream Flow was 7.5 * 105 based on the exit velocity and chord length of the blade. Results indicated that platform film-cooling effectiveness decreased with turbulence intensity, increased with purge Flow rate and density ratio, and possessed an optimum blowing ratio value.
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Influence of Coolant Density on Turbine Blade Platform Film-Cooling
Volume 3: Heat Transfer Parts A and B, 2009Co-Authors: Diganta Narzary, Kuo-chun Liu, Je-chin HanAbstract:Detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform of a five-blade linear cascade. The parameters chosen were — freestream turbulence intensity, upstream stator-rotor purge Flow rate, discrete-hole film-cooling blowing ratio, and coolant-to-Mainstream density ratio. The measurement technique adopted was temperature sensitive paint (TSP) technique. Two turbulence intensities of 4.2% and 10.5%; three purge Flows between the range of 0.25% and 0.75% of Mainstream Flow rate; three blowing ratios between 1.0 and 2.0; and three density ratios between 1.1 and 2.1 were investigated. Purge Flow was supplied via a typical double-toothed stator-rotor seal, whereas the discrete-hole film cooling was accomplished via two rows of cylindrical holes arranged along the length of the platform. The inlet and the exit Mach numbers were 0.27 and 0.44, respectively. Reynolds number of the Mainstream Flow was 7.5*105 based on the exit velocity and chord length of the blade. Results indicated that platform film-cooling effectiveness decreased with turbulence intensity, increased with purge Flow rate and density ratio, and possessed an optimum blowing ratio value. The improved effectiveness with density ratio was further validated by the pressure sensitive paint (PSP) technique.Copyright © 2009 by ASME
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Film-Cooling Effectiveness on a Rotating Blade Platform
Journal of Turbomachinery, 2008Co-Authors: A. Suryanarayanan, Shantanu Mhetras, Meinhard T. Schobeiri, Je-chin HanAbstract:Film cooling effectiveness measurements under rotation were performed on the rotor blade platform using a pressure sensitive paint (PSP) technique. The present study examines, in particular, the film cooling effectiveness due to purging of coolant from the wheel-space cavity through the circumferential clearance gap provided between the stationary and rotating components of the turbine. The experimental investigation is carried out in a new three-stage turbine facility, recently designed and taken into operation at the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. This new turbine rotor has been used to facilitate coolant injection through this stator-rotor gap upstream of the first stage rotor blade. The gap was inclined at 25 deg to Mainstream Flow to allow the injected coolant to form a film along the passage platform. The effects of turbine rotating conditions on the blade platform film cooling effectiveness were investigated at three speeds of 2550 rpm, 2000 rpm, and 1500 rpm with corresponding incidence angles of 23.2 deg, 43.4 deg, and 54.8 deg, respectively. Four different coolant-to-Mainstream mass Flow ratios varying from 0.5% to 2.0% were tested at each rotational speed. Aerodynamic measurements were performed at the first stage stator exit using a radially traversed five-hole probe to quantify the Mainstream Flow at this station. Results indicate that film cooling effectiveness increases with an increase in the coolant-to-Mainstream mass Flow ratios for all turbine speeds. Higher turbine rotation speeds show more local film cooling effectiveness spread on the platform with increasing magnitudes.
J. P. Longley - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Stator-Rotor Hub Sealing Flow on the Mainstream Aerodynamics of a Turbine
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:An investigation into the effect of stator-rotor hub gap sealing Flow on turbine performance is presented. Efficiency measurements and rotor exit area traverse data from a low speed research turbine are reported. Tests carried out over a range of sealing Flow conditions show that the turbine efficiency decreases with increasing sealant Flow rate but that this penalty is reduced by swirling the sealant Flow. Results from time-accurate and steady-state simulations using a three-dimensional multi-block RANS solver are presented with particular emphasis paid to the mechanisms of loss production. The contributions toward entropy generation of the mixing of the sealant fluid with the Mainstream Flow and of the perturbed rotor secondary Flows are assessed. The importance of unsteady stator wake/sealant Flow interactions is also highlighted.Copyright © 2006 by ASME
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The interaction of turbine inter-platform leakage Flow with the Mainstream Flow
Journal of Turbomachinery, 2005Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:Individual nozzle guide vanes (NGV???s) in modern aeroengines are often cast as a single piece with integral hub and casing endwalls. When in operation, there is a leakage Flow through the chord-wise interplatform gaps. An investigation into the effect of this leakage Flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low-speed research turbine are reported. Tests show that this leakage Flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage Flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock Reynolds-averaged Navier-Stokes solver are presented with particular emphasis paid to the physics of the Mainstream/leakage interaction and the loss generation.
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The Interaction of Turbine Inter-Platform Leakage Flow With the Mainstream Flow
Volume 6: Turbo Expo 2005 Parts A and B, 2005Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:Individual nozzle guide vanes (NGVs) in modern aero engines are often cast as a single piece with integral hub and casing endwalls. When in operation there is a leakage Flow through the chord-wise inter-platform gaps. An investigation into the effect of this leakage Flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low speed research turbine are reported. Tests show that this leakage Flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage Flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock RANS solver are presented with particular emphasis paid to the physics of the Mainstream/leakage interaction and the loss generation.Copyright © 2005 by ASME
Graham Pullan - One of the best experts on this subject based on the ideXlab platform.
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Estimating the Loss Associated With Film Cooling for a Turbine Stage
Journal of Turbomachinery, 2011Co-Authors: Chia Hui Lim, Graham Pullan, John NorthallAbstract:A methodology is presented to allow designers to estimate the penalty for turbine efficiency associated with film cooling. The approach is based on the control volume analysis of Hartsel and the entropy-based formulations of Young and Wilcock. The present work extends these techniques to include Flow ejected at compound angles and uses three-dimensional computational fluid dynamics (CFD) to provide the Mainstream Flow properties. The method allows the loss contribution from each hole to be identified separately. The proposed method is applied to an aeroengine high-pressure turbine stage. It is found that, if the efficiency definition includes all irreversibilities, the penalty associated with film cooling would be 8.0%. However, if the pragmatic approach is adopted whereby the unavoidable entropy generated due to the equilibration of coolant and Mainstream static temperatures is ignored, the efficiency penalty is 0.7%. Finally, a series of case studies is used to quantify the impact of changes to the local Mainstream Flow direction and coolant ejection angle on the predicted turbine efficiency. It is shown, quantitatively, that reducing the angle between the directions of the coolant and Mainstream Flows offers the greatest potential for the designer to improve film-cooled turbine efficiency.
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Estimating the Loss Associated With Film Cooling for a Turbine Stage
Volume 4: Heat Transfer Parts A and B, 2010Co-Authors: Chia Hui Lim, Graham Pullan, John NorthallAbstract:A methodology is presented to allow designers to estimate the penalty for turbine efficiency associated with film cooling. The approach is based on the control volume analysis of Hartsel and the entropy-based formulations of Young and Wilcock. The present work extends these techniques to include Flow ejected at compound angles and uses three-dimensional CFD to provide the Mainstream Flow properties. The method allows the loss contribution from each hole to be identified separately. The proposed method is applied to an aeroengine high-pressure turbine stage. It is found that, if the efficiency definition includes all irreversibilities, the penalty associated with film cooling would be 8.0%. However, if the pragmatic approach is adopted whereby the unavoidable entropy generated due to the equilibration of coolant and Mainstream static temperatures is ignored, the efficiency penalty is 0.7%. Finally, a series of case studies is used to quantify the impact of changes to the local Mainstream Flow direction and coolant ejection angle on the predicted turbine efficiency. It is shown, quantitatively, that reducing the angle between the directions of the coolant and Mainstream Flows offers the greatest potential for the designer to improve film cooled turbine efficiency.Copyright © 2010 by ASME
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The Effect of Stator-Rotor Hub Sealing Flow on the Mainstream Aerodynamics of a Turbine
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:An investigation into the effect of stator-rotor hub gap sealing Flow on turbine performance is presented. Efficiency measurements and rotor exit area traverse data from a low speed research turbine are reported. Tests carried out over a range of sealing Flow conditions show that the turbine efficiency decreases with increasing sealant Flow rate but that this penalty is reduced by swirling the sealant Flow. Results from time-accurate and steady-state simulations using a three-dimensional multi-block RANS solver are presented with particular emphasis paid to the mechanisms of loss production. The contributions toward entropy generation of the mixing of the sealant fluid with the Mainstream Flow and of the perturbed rotor secondary Flows are assessed. The importance of unsteady stator wake/sealant Flow interactions is also highlighted.Copyright © 2006 by ASME
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The interaction of turbine inter-platform leakage Flow with the Mainstream Flow
Journal of Turbomachinery, 2005Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:Individual nozzle guide vanes (NGV???s) in modern aeroengines are often cast as a single piece with integral hub and casing endwalls. When in operation, there is a leakage Flow through the chord-wise interplatform gaps. An investigation into the effect of this leakage Flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low-speed research turbine are reported. Tests show that this leakage Flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage Flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock Reynolds-averaged Navier-Stokes solver are presented with particular emphasis paid to the physics of the Mainstream/leakage interaction and the loss generation.
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The Interaction of Turbine Inter-Platform Leakage Flow With the Mainstream Flow
Volume 6: Turbo Expo 2005 Parts A and B, 2005Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:Individual nozzle guide vanes (NGVs) in modern aero engines are often cast as a single piece with integral hub and casing endwalls. When in operation there is a leakage Flow through the chord-wise inter-platform gaps. An investigation into the effect of this leakage Flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low speed research turbine are reported. Tests show that this leakage Flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage Flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock RANS solver are presented with particular emphasis paid to the physics of the Mainstream/leakage interaction and the loss generation.Copyright © 2005 by ASME
Kevin Reid - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Stator-Rotor Hub Sealing Flow on the Mainstream Aerodynamics of a Turbine
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:An investigation into the effect of stator-rotor hub gap sealing Flow on turbine performance is presented. Efficiency measurements and rotor exit area traverse data from a low speed research turbine are reported. Tests carried out over a range of sealing Flow conditions show that the turbine efficiency decreases with increasing sealant Flow rate but that this penalty is reduced by swirling the sealant Flow. Results from time-accurate and steady-state simulations using a three-dimensional multi-block RANS solver are presented with particular emphasis paid to the mechanisms of loss production. The contributions toward entropy generation of the mixing of the sealant fluid with the Mainstream Flow and of the perturbed rotor secondary Flows are assessed. The importance of unsteady stator wake/sealant Flow interactions is also highlighted.Copyright © 2006 by ASME
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The interaction of turbine inter-platform leakage Flow with the Mainstream Flow
Journal of Turbomachinery, 2005Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:Individual nozzle guide vanes (NGV???s) in modern aeroengines are often cast as a single piece with integral hub and casing endwalls. When in operation, there is a leakage Flow through the chord-wise interplatform gaps. An investigation into the effect of this leakage Flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low-speed research turbine are reported. Tests show that this leakage Flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage Flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock Reynolds-averaged Navier-Stokes solver are presented with particular emphasis paid to the physics of the Mainstream/leakage interaction and the loss generation.
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The Interaction of Turbine Inter-Platform Leakage Flow With the Mainstream Flow
Volume 6: Turbo Expo 2005 Parts A and B, 2005Co-Authors: Kevin Reid, John D. Denton, Graham Pullan, Eric Curtis, J. P. LongleyAbstract:Individual nozzle guide vanes (NGVs) in modern aero engines are often cast as a single piece with integral hub and casing endwalls. When in operation there is a leakage Flow through the chord-wise inter-platform gaps. An investigation into the effect of this leakage Flow on turbine performance is presented. Efficiency measurements and NGV exit area traverse data from a low speed research turbine are reported. Tests show that this leakage Flow can have a significant impact on turbine performance, but that below a threshold leakage fraction this penalty does not rise with increasing leakage Flow rate. The effect of various seal clearances are also investigated. Results from steady-state simulations using a three-dimensional multiblock RANS solver are presented with particular emphasis paid to the physics of the Mainstream/leakage interaction and the loss generation.Copyright © 2005 by ASME
Carl M. Sangan - One of the best experts on this subject based on the ideXlab platform.
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An Advanced Single-Stage Turbine Facility for Investigating Nonaxisymmetric Contoured Endwalls in the Presence of Purge Flow
Journal of Engineering for Gas Turbines and Power, 2019Co-Authors: Robin Jones, Oliver J. Pountney, Bjorn L. Cleton, Liam E. Wood, B. Deneys J. Schreiner, A. J. Carvalho Figueiredo, James A. Scobie, David Cleaver, Gary D. Lock, Carl M. SanganAbstract:Abstract In modern gas turbines, endwall contouring (EWC) is employed to modify the static pressure field downstream of the vanes and minimize the growth of secondary Flow structures developed in the blade passage. Purge Flow (or egress) from the upstream rim-seal interferes with the Mainstream Flow, adding to the loss generated in the rotor. Despite this, EWC is typically designed without consideration of Mainstream–egress interactions. The performance gains offered by EWC can be reduced, or in the limit eliminated, when purge air is considered. In addition, EWC can result in a reduction in sealing effectiveness across the rim seal. Consequently, industry is pursuing a combined design approach that encompasses the rim-seal, seal-clearance profile, and EWC on the rotor endwall. This paper presents the design of and preliminary results from a new single-stage axial turbine facility developed to investigate the fundamental fluid dynamics of egress–Mainstream Flow interactions. To the authors' knowledge, this is the only test facility in the world capable of investigating the interaction effects between cavity Flows, rim seals, and EWC. The design of optical measurement capabilities for future studies, employing volumetric velocimetry (VV) and planar laser-induced fluorescence (PLIF), is also presented. The fluid-dynamically scaled rig operates at benign pressures and temperatures suited to these techniques and is modular. The facility enables expedient interchange of EWC (integrated into the rotor bling), blade-fillet and rim-seal geometries. The measurements presented in this paper include: gas concentration effectiveness and swirl measurements on the stator wall and in the wheel-space core; pressure distributions around the nozzle guide vanes (NGV) at three different spanwise locations; pitchwise static pressure distributions downstream of the NGV at four axial locations on the stator platform.
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An Advanced Single-Stage Turbine Facility for Investigating Non-Axisymmetric Contoured Endwalls in the Presence of Purge Flow
Volume 2B: Turbomachinery, 2019Co-Authors: Robin R. Jones, Oliver J. Pountney, Bjorn L. Cleton, Liam E. Wood, B. Deneys J. Schreiner, A. J. Carvalho Figueiredo, James A. Scobie, Gary D. Lock, David J. Cleaver, Carl M. SanganAbstract:Abstract In modern gas turbines, endwall contouring (EWC) is employed to modify the static pressure field downstream of the vanes and minimise the growth of secondary Flow structures developed in the blade passage. Purge Flow (or egress) from the upstream rim-seal interferes with the Mainstream Flow, adding to the loss generated in the rotor. Despite this, EWC is typically designed without consideration of Mainstream-egress interactions. The performance gains offered by EWC can be reduced, or in the limit eliminated, when purge air is considered. In addition, EWC can result in a reduction in sealing effectiveness across the rim seal. Consequently, industry is pursuing a combined design approach that encompasses the rim-seal, seal-clearance profile and EWC on the rotor endwall. This paper presents the design of, and preliminary results from a new single-stage axial turbine facility developed to investigate the fundamental fluid dynamics of egress-Mainstream Flow interactions. To the authors’ knowledge this is the only test facility in the world capable of investigating the interaction effects between cavity Flows, rim seals and EWC. The design of optical measurement capabilities for future studies, employing volumetric velocimetry and planar laser induced fluorescence are also presented. The fluid-dynamically scaled rig operates at benign pressures and temperatures suited to these techniques and is modular. The facility enables expedient interchange of EWC (integrated into the rotor bling), blade-fillet and rim-seals geometries. The measurements presented in this paper include: gas concentration effectiveness and swirl measurements on the stator wall and in the wheel-space core; pressure distributions around the nozzle guide vanes at three different spanwise locations; pitchwise static pressure distributions downstream of the nozzle guide vane at four axial locations on the stator platform.
