The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform

Hukam Mongia - One of the best experts on this subject based on the ideXlab platform.

  • Modeling of Jets in Cross Flow with RANS and LES Part I: Momentum Transport for Low R w/ RANS
    43rd AIAA Aerospace Sciences Meeting and Exhibit, 2005
    Co-Authors: Zhongtao Dai, Shih-yang Hsieh, Hukam Mongia
    Abstract:

    ABSTRACT Four models (standard k-e, Realizable k-e, Reynolds stress, and Spalart-Allmaras turbulence models) along with the two near-Wall treatments (Nonequilibrium Wall Function, and enhanced Wall treatment) of software were assesses for low to moderate jet momentum (velocity) ratios of interest in gas turbine combustors. A systematic study was taken to establish RANS capability to be followed by back-to-back assessment of LES/DES capabilities. INTRODUCTION

  • Combustor Diffuser Modeling Part V: Validation with a Three Passage Diffuser Rig Data
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, G. Hsaio, Psvs Sreedhar, M. Ravindra
    Abstract:

    ABSTRACT A full-scale 3-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet, the three profilers that provide center-, innerand outer-peak profiles at the prediffuser inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig. In general, CFD gave good agreement with data as shown in the following table.

  • Combustor Diffuser Modeling Part VI: Validation with a Four Passage Diffuser Rig Data
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, Psvs Sreedhar, M. Ravindra, M. Mueller, Z. Dai, P. Arvind
    Abstract:

    A full-scale 4-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet, the three profilers that provide center-, innerand outer-peak profiles at the prediffuser inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig. In general, CFD gave good agreement with data considering the complexity of the flow field.

  • Combustor Diffuser Modeling Part III: Validation w/ Typical Separating Single Passage Diffusers Combustor Diffuser Modeling
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, G. Hsaio, Psvs Sreedhar, David Louis Burrus, K. Habeeb
    Abstract:

    A full-scale single-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig fitted with a center-peak profiler that documented back-to-back performance between: 1) Diffuser with bow-tie and opposed-ring profilers, Runs 3, 7 and 8; 2) Increased area diffuser compared with the baseline design, Run 3 compared with Run 9. In general, CFD gave good agreement with data considering the complexity of the flow field.

  • Combustor Diffuser Modeling Part IV: Effect of Cowling Geometry, Mixer Size and Nozzle Blockage
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, G. Hsaio, Psvs Sreedhar, David Louis Burrus, A. Rao, S. Ismail
    Abstract:

    A full-scale single-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig fitted with a center-peak profiler that documented back-to-back performance between: 1) Dome fitted with a baseline cowling, Run 3 and without cowling, Run 6, 2) Reduced cowling inlet area, Run 3 compared with Run 7, 3) a slightly modified cowling geometry along with increased nozzle tip diameter, Run 11 versus Run 3, and 4) with 20% increased blockage caused by the fuel nozzle stem, Run 12 versus Run 3. In general, CFD gave good agreement with data considering the complexity of the flow field.

H Yang - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of Film Cooling and Heat Transfer on a Rotating Blade Platform With Stator-Rotor Purge and Discrete Film-Hole Flows in a 1-12 Turbine Stage
    Journal of Turbomachinery-transactions of The Asme, 2009
    Co-Authors: H Yang, Hamn-ching Chen, M. T. Schobeir
    Abstract:

    Numerical simulations were performed to predict the film cooling effectiveness and heat transfer coefficient distributions on a rotating blade platform with stator-rotor purge flow and downstream discrete film-hole flows in a 1-1/2 turbine stage using a Reynolds stress turbulence model together with a Nonequilibrium Wall Function. Simulations were carried out with sliding mesh for the rotor under three rotating speeds (2000 rpm, 2550 rpm, and 3000 rpm) to investigate the effects of rotation and stator-rotor interaction on the rotor blade-platform purge flow cooling and discrete-hole film cooling and heat transfer. The adiabatic film cooling effectiveness and heat transfer coefficients were calculated using the adiabatic Wall temperatures with and without coolant to examine the true coolant protection excluding the effect of turbine work process. The stator-rotor interaction strongly impacts the purge slot film cooling and heat transfer at the platform leading portion while only slightly affects the downstream discrete-hole film cooling near the platform trailing portion. In addition, the effect of turbine work process on the film cooling effectiveness and the associated heat transfer coefficients have been reported.

  • Film-Cooling Prediction on Rotor Blade Leading Edge in 1-1/2 Turbine Stage
    Journal of Thermophysics and Heat Transfer, 2008
    Co-Authors: H Yang, Hamn-ching Chen, Je-chin Han, Hee-koo Moon
    Abstract:

    Numerical simulations have been performed to predict the film-cooling effectiveness and the associated heat transfer coefficient on the leading edge of a rotating blade in a 1-1/2 turbine stage. The Reynolds stress turbulence model together with the Nonequilibrium Wall Function is employed in the simulation. A sliding grid is used for the rotor domain, and an interface technique is employed to exchange the information between stator and rotor domains. Simulations are carried out for both the design and the off-design conditions to investigate the effects of the stator-rotor interaction on the film-cooling characteristics. The unsteady characteristics of the heat transfer coefficient and film-cooling effectiveness at various rotating speeds are also investigated. With increasing rotating speed, the tilt stagnation line on the leading edge of a rotor moves from the pressure side to the suction side, and the instantaneous coolant streamlines shift from the suction side to the pressure side. This trend is supported by the experimental results. In addition, the detailed instantaneous heat transfer coefficient and film-cooling effectiveness at various time phases, as well as different rotating speeds, are also reported.

  • Film-Cooling Prediction on Turbine Blade Tip with Various Film Hole Configurations
    Journal of Thermophysics and Heat Transfer, 2006
    Co-Authors: H Yang, Hamn-ching Chen, Je-chin Han
    Abstract:

    Different film hole arrangements on the plane and squealer tips of a turbine blade are investigated using a Reynolds stress turbulence model and Nonequilibrium Wall Function. The three film hole configurations considered are 1) the camber arrangement, where the film-cooling holes are located on the mid-camber line of the tips; 2) the upstream arrangement, where the film holes are located upstream of the tip leakage flow and high heat transfer region; and 3) the two-rows arrangement, which is a combination of the camber and upstream arrangements. Calculations were performed first for the nonrotating cases under low inlet/outlet pressure ratio conditions with three different blowing ratios. The predicted heat transfer coefficients are in good agreement with the experimental data, but the film-cooling effectiveness is somewhat overpredicted downstream of the film holes. Simulations were then performed for the nonrotating and rotating camber line film hole configuration under high inlet/outlet pressure ratio conditions, which are close to engine conditions. It is found that the rotation decreases the plane tip film-cooling effectiveness but only slightly affects the squealer tip film cooling. However, the rotation significantly increases heat transfer coefficient on the shrouds.

Hamn-ching Chen - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of Film Cooling and Heat Transfer on a Rotating Blade Platform With Stator-Rotor Purge and Discrete Film-Hole Flows in a 1-12 Turbine Stage
    Journal of Turbomachinery-transactions of The Asme, 2009
    Co-Authors: H Yang, Hamn-ching Chen, M. T. Schobeir
    Abstract:

    Numerical simulations were performed to predict the film cooling effectiveness and heat transfer coefficient distributions on a rotating blade platform with stator-rotor purge flow and downstream discrete film-hole flows in a 1-1/2 turbine stage using a Reynolds stress turbulence model together with a Nonequilibrium Wall Function. Simulations were carried out with sliding mesh for the rotor under three rotating speeds (2000 rpm, 2550 rpm, and 3000 rpm) to investigate the effects of rotation and stator-rotor interaction on the rotor blade-platform purge flow cooling and discrete-hole film cooling and heat transfer. The adiabatic film cooling effectiveness and heat transfer coefficients were calculated using the adiabatic Wall temperatures with and without coolant to examine the true coolant protection excluding the effect of turbine work process. The stator-rotor interaction strongly impacts the purge slot film cooling and heat transfer at the platform leading portion while only slightly affects the downstream discrete-hole film cooling near the platform trailing portion. In addition, the effect of turbine work process on the film cooling effectiveness and the associated heat transfer coefficients have been reported.

  • Film-Cooling Prediction on Rotor Blade Leading Edge in 1-1/2 Turbine Stage
    Journal of Thermophysics and Heat Transfer, 2008
    Co-Authors: H Yang, Hamn-ching Chen, Je-chin Han, Hee-koo Moon
    Abstract:

    Numerical simulations have been performed to predict the film-cooling effectiveness and the associated heat transfer coefficient on the leading edge of a rotating blade in a 1-1/2 turbine stage. The Reynolds stress turbulence model together with the Nonequilibrium Wall Function is employed in the simulation. A sliding grid is used for the rotor domain, and an interface technique is employed to exchange the information between stator and rotor domains. Simulations are carried out for both the design and the off-design conditions to investigate the effects of the stator-rotor interaction on the film-cooling characteristics. The unsteady characteristics of the heat transfer coefficient and film-cooling effectiveness at various rotating speeds are also investigated. With increasing rotating speed, the tilt stagnation line on the leading edge of a rotor moves from the pressure side to the suction side, and the instantaneous coolant streamlines shift from the suction side to the pressure side. This trend is supported by the experimental results. In addition, the detailed instantaneous heat transfer coefficient and film-cooling effectiveness at various time phases, as well as different rotating speeds, are also reported.

  • Film-Cooling Prediction on Turbine Blade Tip with Various Film Hole Configurations
    Journal of Thermophysics and Heat Transfer, 2006
    Co-Authors: H Yang, Hamn-ching Chen, Je-chin Han
    Abstract:

    Different film hole arrangements on the plane and squealer tips of a turbine blade are investigated using a Reynolds stress turbulence model and Nonequilibrium Wall Function. The three film hole configurations considered are 1) the camber arrangement, where the film-cooling holes are located on the mid-camber line of the tips; 2) the upstream arrangement, where the film holes are located upstream of the tip leakage flow and high heat transfer region; and 3) the two-rows arrangement, which is a combination of the camber and upstream arrangements. Calculations were performed first for the nonrotating cases under low inlet/outlet pressure ratio conditions with three different blowing ratios. The predicted heat transfer coefficients are in good agreement with the experimental data, but the film-cooling effectiveness is somewhat overpredicted downstream of the film holes. Simulations were then performed for the nonrotating and rotating camber line film hole configuration under high inlet/outlet pressure ratio conditions, which are close to engine conditions. It is found that the rotation decreases the plane tip film-cooling effectiveness but only slightly affects the squealer tip film cooling. However, the rotation significantly increases heat transfer coefficient on the shrouds.

Je-chin Han - One of the best experts on this subject based on the ideXlab platform.

  • Film-Cooling Prediction on Rotor Blade Leading Edge in 1-1/2 Turbine Stage
    Journal of Thermophysics and Heat Transfer, 2008
    Co-Authors: H Yang, Hamn-ching Chen, Je-chin Han, Hee-koo Moon
    Abstract:

    Numerical simulations have been performed to predict the film-cooling effectiveness and the associated heat transfer coefficient on the leading edge of a rotating blade in a 1-1/2 turbine stage. The Reynolds stress turbulence model together with the Nonequilibrium Wall Function is employed in the simulation. A sliding grid is used for the rotor domain, and an interface technique is employed to exchange the information between stator and rotor domains. Simulations are carried out for both the design and the off-design conditions to investigate the effects of the stator-rotor interaction on the film-cooling characteristics. The unsteady characteristics of the heat transfer coefficient and film-cooling effectiveness at various rotating speeds are also investigated. With increasing rotating speed, the tilt stagnation line on the leading edge of a rotor moves from the pressure side to the suction side, and the instantaneous coolant streamlines shift from the suction side to the pressure side. This trend is supported by the experimental results. In addition, the detailed instantaneous heat transfer coefficient and film-cooling effectiveness at various time phases, as well as different rotating speeds, are also reported.

  • Film-Cooling Prediction on Turbine Blade Tip with Various Film Hole Configurations
    Journal of Thermophysics and Heat Transfer, 2006
    Co-Authors: H Yang, Hamn-ching Chen, Je-chin Han
    Abstract:

    Different film hole arrangements on the plane and squealer tips of a turbine blade are investigated using a Reynolds stress turbulence model and Nonequilibrium Wall Function. The three film hole configurations considered are 1) the camber arrangement, where the film-cooling holes are located on the mid-camber line of the tips; 2) the upstream arrangement, where the film holes are located upstream of the tip leakage flow and high heat transfer region; and 3) the two-rows arrangement, which is a combination of the camber and upstream arrangements. Calculations were performed first for the nonrotating cases under low inlet/outlet pressure ratio conditions with three different blowing ratios. The predicted heat transfer coefficients are in good agreement with the experimental data, but the film-cooling effectiveness is somewhat overpredicted downstream of the film holes. Simulations were then performed for the nonrotating and rotating camber line film hole configuration under high inlet/outlet pressure ratio conditions, which are close to engine conditions. It is found that the rotation decreases the plane tip film-cooling effectiveness but only slightly affects the squealer tip film cooling. However, the rotation significantly increases heat transfer coefficient on the shrouds.

Psvs Sreedhar - One of the best experts on this subject based on the ideXlab platform.

  • Combustor Diffuser Modeling Part V: Validation with a Three Passage Diffuser Rig Data
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, G. Hsaio, Psvs Sreedhar, M. Ravindra
    Abstract:

    ABSTRACT A full-scale 3-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet, the three profilers that provide center-, innerand outer-peak profiles at the prediffuser inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig. In general, CFD gave good agreement with data as shown in the following table.

  • Combustor Diffuser Modeling Part VI: Validation with a Four Passage Diffuser Rig Data
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, Psvs Sreedhar, M. Ravindra, M. Mueller, Z. Dai, P. Arvind
    Abstract:

    A full-scale 4-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet, the three profilers that provide center-, innerand outer-peak profiles at the prediffuser inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig. In general, CFD gave good agreement with data considering the complexity of the flow field.

  • Combustor Diffuser Modeling Part III: Validation w/ Typical Separating Single Passage Diffusers Combustor Diffuser Modeling
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, G. Hsaio, Psvs Sreedhar, David Louis Burrus, K. Habeeb
    Abstract:

    A full-scale single-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig fitted with a center-peak profiler that documented back-to-back performance between: 1) Diffuser with bow-tie and opposed-ring profilers, Runs 3, 7 and 8; 2) Increased area diffuser compared with the baseline design, Run 3 compared with Run 9. In general, CFD gave good agreement with data considering the complexity of the flow field.

  • Combustor Diffuser Modeling Part IV: Effect of Cowling Geometry, Mixer Size and Nozzle Blockage
    40th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit, 2004
    Co-Authors: Hukam Mongia, G. Hsaio, Psvs Sreedhar, David Louis Burrus, A. Rao, S. Ismail
    Abstract:

    A full-scale single-passage combustor diffusion system has been analyzed with FLUENT code using its grid generation package, the standard k-e model and the Nonequilibrium Wall Function. Inlet conditions were calculated using through the rig inlet. 3-D model predictions were compared with data from a full-scale annular diffuser rig fitted with a center-peak profiler that documented back-to-back performance between: 1) Dome fitted with a baseline cowling, Run 3 and without cowling, Run 6, 2) Reduced cowling inlet area, Run 3 compared with Run 7, 3) a slightly modified cowling geometry along with increased nozzle tip diameter, Run 11 versus Run 3, and 4) with 20% increased blockage caused by the fuel nozzle stem, Run 12 versus Run 3. In general, CFD gave good agreement with data considering the complexity of the flow field.