Endwall Heat Transfer and Cooling Performance of a Transonic Turbine Vane With Upstream Injection Flow

2021 ◽  
Author(s):  
Zhigang Li ◽  
Bo Bai ◽  
Jun Li ◽  
Shuo Mao ◽  
Wing Ng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Cooling Performance ◽  
Injection Flow ◽  
Turbine Vane ◽  
Transonic Turbine

Endwall Heat Transfer and Cooling Performance of a Transonic Turbine Vane With Upstream Injection Flow

2020 ◽  
Author(s):  
Zhigang Li ◽  
Bo Bai ◽  
Jun Li ◽  
Shuo Mao ◽  
Wing Ng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Film Cooling ◽  
Secondary Flows ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Injection Flow ◽  
Coolant Injection ◽  
Turbine Vane ◽  
Endwall Cooling

Abstract Flow fields near the turbine vane endwall region are very complicated due to the presence of highly three-dimensional passage vortices and endwall secondary flows. This makes it challenging for the endwall to be effectively cooled by employing traditional endwall cooling methods, such as impingement cooling combined with local film cooling inside the vane passage. One effective endwall cooling scheme: coolant injection flow through discrete holes upstream of the vane leading edge on the endwall, has been considered by many gas turbine companies. The present paper focuses on endwall film cooling effectiveness evaluation with upstream coolant injection through discrete holes. Detailed experimental and numerical studies on endwall heat transfer and cooling performance with coolant injection flow through upstream discrete holes is presented in this paper. High resolution heat transfer coefficient (HTC) and adiabatic film cooling effectiveness values were measured using a transient infrared thermography technique on an axisymmetric contoured endwall. The endwall tested was a scaled up inner endwall of an industrial transonic turbine vane with double-row discrete cylindrical film cooling holes located 0.39Cx upstream of the vane leading edge. The tests were performed in a transonic linear cascade blow-down wind tunnel facility. Conditions were representative of a land-based power generation turbine with exit Mach number of 0.85 corresponding to exit Reynolds number of 1.5 × 106, based on exit condition and axial chord length. A high turbulence level of 16% with an integral length scale of 3.6%P was generated using inlet turbulence grid to reproduce the typical turbulence conditions in real turbine. Low temperature air was used to simulate the typical coolant-to-mainstream condition by controlling two parameters of the upstream coolant injection flow: mass flow rate to determine the coolant-to-mainstream blowing ratio (BR = 2.5, 3.5), and gas temperature to determine the density ratio (DR = 1.2). To highlight the interactions between the upstream coolant flow and the passage secondary flow combined with the influence on the endwall heat transfer and cooling performance, a comparison of CFD predictions to experimental results was performed by solving steady-state Reynolds-Averaged Navier-Stokes (RANS) using the commercial CFD solver ANSYS Fluent v.15. A detailed numerical method validation was performed for four different Reynolds-averaged turbulence models. The Realizable κ-ϵ model was validated to be suitable to obtain reliable numerical solution. The influences of a wide range of coolant-to-mainstream blowing ratios (BR = 1.0, 1.5, 1.9, 2.5, 3.0, 3.5) were numerically studied. Complex interactions between coolant injections and secondary flows in vane passage were presented and discussed. Results indicate that for lower values of BR, the endwall coolant coverage from the upstream double-row discrete holes is strongly controlled by the passage secondary flow, thus the cooling effectiveness is very poor. As the BR increases, the strong secondary flow in vane passage can be suppressed by the coolant injections and begin to be almost eliminated when BR increases to a critical value (BR = 2.5 – 3.0). Beyond the critical BR, most of the injected coolant begins to lift off from the endwall and penetrate significantly into the mainstream flow, yielding inefficient endwall cooling performance.

Endwall Heat Transfer and Cooling Performance of a Transonic Turbine Vane with Upstream Injection Flow

2021 ◽  
pp. 1-24
Author(s):  
Zhigang LI ◽  
Bo Bai ◽  
Jun Li ◽  
Shuo Mao ◽  
Wing Ng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Density Ratio ◽  
Gas Temperature ◽  
Blow Down ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Injection Flow ◽  
Coolant Injection ◽  
Exit Mach Number

Abstract Detailed experimental and numerical studies on endwall heat transfer and cooling performance with coolant injection flow through upstream discrete holes is presented in this paper. High resolution heat transfer coefficient (HTC) and adiabatic film cooling effectiveness values were measured using a transient infrared thermography technique on an axisymmetric contoured endwall. The tests were performed in a transonic linear cascade blow-down wind tunnel facility. Conditions were representative of a land-based power generation turbine with exit Mach number of 0.85 corresponding to exit Reynolds number of 1.5 × 106, based on exit condition and axial chord length. A high turbulence level of 16% with an integral length scale of 3.6%P was generated using inlet turbulence grid to reproduce the typical turbulence conditions in real turbine. Low temperature air was used to simulate the typical coolant-to-mainstream condition by controlling two parameters of the upstream coolant injection flow: mass flow rate to determine the coolant-to-mainstream blowing ratio (BR = 2.5, 3.5), and gas temperature to determine the density ratio (DR = 1.2). To highlight the interactions between the upstream coolant flow and the passage secondary flow combined with the influence on the endwall heat transfer and cooling performance, a comparison of CFD predictions to experimental results was performed by solving steady-state Reynolds-Averaged Navier-Stokes (RANS) using the commercial CFD solver ANSYS Fluent V.15.

Detailed Velocity and Heat Transfer Measurements in an Advanced Gas Turbine Vane Insert Using MRV and IR Thermometry

2020 ◽  
Author(s):  
Michael J. Benson ◽  
David Bindon ◽  
Mattias Cooper ◽  
F. Todd Davidson ◽  
Benjamin Duhaime ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Gas Turbine ◽  
Computational Models ◽  
Internal Heat ◽  
Internal Cooling ◽  
Data Set ◽  
Ir Camera ◽  
Cooling Performance ◽  
Turbine Vane

Abstract This work reports the results of paired experiments for a complex internal cooling flow within a gas turbine vane using Magnetic Resonance Velocimetry (MRV) and steady-state Infrared (IR) thermometry. A scaled model of the leading edge insert for a gas turbine vane with multi-pass impingement was designed, built using stereolithography (SLA) fabrication methods, and tested using MRV techniques to collect a three-dimensional, three-component velocity field data set for a fully turbulent test case. Stagnation and recirculation zones were identified and assessed in terms of impact on potential cooling performance. A paired experiment employed an IR camera to measure the temperature profile data of a thin, heated stainless steel impingement surface modeling the inside turbine blade wall cooled by the impingement from the vane cooling insert, providing complementary data sets. The temperature data allow for the calculation of wall heat transfer characteristics, including the Nusselt number distribution for cooling performance analysis to inform design and validate computational models. Quantitative and qualitative comparisons of the paired results show that the flow velocity and cooling performance are highly coupled. Module-to-module variation in the surface Nusselt number distributions are evident, attributable to the complex interaction between transverse and impinging flows within the apparatus. Finally, a comparison with internal heat transfer correlations is conducted using the data from Florschuetz [1]. Measurement uncertainty was assessed and estimated to be approximately +7% for velocity and ranging from +3% to +10% for Nusselt number.

Influence of Coolant on Cooling Performance Sensitivity of Internally Convective Turbine Vane

2021 ◽  
Author(s):  
Thanapat Chotroongruang ◽  
Prasert Prapamonthon ◽  
Rungsimun Thongdee ◽  
Thanapat Thongmuenwaiyathon ◽  
Zhenxu Sun ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Film Cooling ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Turbine Engine ◽  
Performance Sensitivity ◽  
Turbine Vane ◽  
Cooling Air

Abstract Based on the Brayton cycle for gas-turbine engines, the high thermal efficiency and power output of a gas-turbine engine can be obtainable when the gas-turbine engine operates at high turbine inlet temperatures. However, turbine components e.g., inlet guide vane, rotor blade, and stator vane request high cooling performance. Typically, internal cooling and film cooling are two effective techniques that are widely used to protect high thermal loads for the turbine components in a state-of-the-art gas turbine. Consequently, the high thermal efficiency and power output can be obtained, and the turbine lifespan can be prolonged, also. On top of that, a comprehensive understanding of flow and heat transfer phenomena in the turbine components is very important. As a result, both experiments and simulations have been used to improve the cooling performance of the turbine components. In fact, the cooling air used in the internal cooling and film cooling is partially extracted from the compressor. Therefore, variations in the cooling air affect the cooling performance of the turbine components directly. This paper presents a numerical study on the influence of the cooling air on cooling-performance sensitivity of an internally convective turbine vane, MARK II using the computational fluid dynamics (CFD)/conjugate heat transfer (CHT) with the SST k-ω turbulence model. Result comparisons are conducted in terms of pressure, temperature, and cooling effectiveness under the effects of the inlet temperature, mass flow rate, turbulence intensity, and flow direction of the cooling air. The cooling-performance sensitivity to the coolant parameters is shown through variations of local cooling effectiveness, and area and volume-weighted average cooling effectiveness.

Degradation of Film Cooling Performance on a Turbine Vane Suction Side due to Surface Roughness

2005 ◽  
Vol 128 (3) ◽  
pp. 547-554 ◽  
Author(s):  
James L. Rutledge ◽  
David Robertson ◽  
David G. Bogard
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Film Cooling ◽  
Extended Period ◽  
Suction Side ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Turbine Vane ◽  
Adiabatic Effectiveness

After an extended period of operation, the surfaces of turbine airfoils become extremely rough due to deposition, spallation, and erosion. The rough airfoil surfaces will cause film cooling performance degradation due to effects on adiabatic effectiveness and heat transfer coefficients. In this study, the individual and combined effects of roughness upstream and downstream of a row of film cooling holes on the suction side of a turbine vane have been determined. Adiabatic effectiveness and heat transfer coefficients were measured for a range of mainstream turbulence levels and with and without showerhead blowing. Using these parameters, the ultimate film cooling performance was quantified in terms of net heat flux reduction. The dominant effect of roughness was a doubling of the heat transfer coefficients. Maximum adiabatic effectiveness levels were also decreased significantly. Relative to a film cooled smooth surface, a film cooled rough surface was found to increase the heat flux to the surface by 30%–70%.

Degradation of Film Cooling Performance on a Turbine Vane Suction Side Due to Surface Roughness

2005 ◽  
Author(s):  
James L. Rutledge ◽  
David Robertson ◽  
David G. Bogard
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Film Cooling ◽  
Extended Period ◽  
Suction Side ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Turbine Vane ◽  
Adiabatic Effectiveness

After an extended period of operation, the surfaces of turbine airfoils become extremely rough due to deposition, spallation, and erosion. The rough airfoil surfaces will cause film cooling performance degradation due to effects on adiabatic effectiveness and heat transfer coefficients. In this study, the individual and combined effects of roughness upstream and downstream of a row of film cooling holes on the suction side of a turbine vane have been determined. Adiabatic effectiveness and heat transfer coefficients were measured for a range of mainstream turbulence levels and with and without showerhead blowing. Using these parameters, the ultimate film cooling performance was quantified in terms of net heat flux reduction. The dominant effect of roughness was a doubling of the heat transfer coefficients. Maximum adiabatic effectiveness levels were also decreased significantly. Relative to a film cooled smooth surface, a film cooled rough surface was found to increase the heat flux to the surface by 30% to 70%.

The Influence of a Laminar Boundary Layer and Laminar Injection on Film Cooling Performance

1982 ◽  
Vol 104 (2) ◽  
pp. 355-362 ◽  
Author(s):  
R. J. Goldstein ◽  
T. Yoshida
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Laminar Boundary Layer ◽  
Film Cooling ◽  
Transport Mechanisms ◽  
Flow Measurements ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Injection Flow

Measurements are reported of the film cooling effectiveness and heat transfer following injection of air into a mainstream of air. A single row of circular injection holes inclined at an angle of 35 deg is used with a lateral spacing between the holes of 3 dia. Low Reynolds number mainstream and injection flow permit studying the influence of a laminar approaching boundary layer and laminar film coolant flow. Measurements of the surface heat transfer taken with no injection indicate that the hole openings can effectively trip the laminar boundary layer into a turbulent flow. The type of the approaching boundary layer has relatively little influence on either the adiabatic effectiveness or the heat transfer with film cooling. The importance of the nature of the injected flow on film cooling performance can at least be qualitatively explained by the differences in the transport mechanisms and in the penetration of the injected air into the mainstream.

Detailed Velocity and Heat Transfer Measurements in an Advanced Gas Turbine Vane Insert Using MRV and IR Thermometry

2021 ◽  
pp. 1-11
Author(s):  
Michael J. Benson ◽  
David Bindon ◽  
Mattias Cooper ◽  
F. Todd Davidson ◽  
Benjamin Duhaime ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Gas Turbine ◽  
Computational Models ◽  
Internal Heat ◽  
Internal Cooling ◽  
Data Set ◽  
Ir Camera ◽  
Cooling Performance ◽  
Turbine Vane

Abstract This work reports the results of paired experiments for a complex internal cooling flow within a gas turbine vane using Magnetic Resonance Velocimetry (MRV) and steady-state Infrared (IR) thermometry. A scaled model of the leading edge insert for a gas turbine vane with multi-pass impingement was designed, built using stereolithography (SLA) fabrication methods, and tested using MRV techniques to collect a three-dimensional, three-component velocity field data set for a fully turbulent test case. Stagnation and recirculation zones were identified and assessed in terms of impact on potential cooling performance. A paired experiment employed an IR camera to measure the temperature profile data of a thin, heated stainless steel impingement surface modeling the inside turbine blade wall cooled by the impingement from the vane cooling insert, providing complementary data sets. The temperature data allow for the calculation of wall heat transfer characteristics, including the Nusselt number distribution for cooling performance analysis to inform design and validate computational models. Quantitative and qualitative comparisons of the paired results show that the flow velocity and cooling performance are highly coupled. Module-to-module variation in the surface Nusselt number distributions are evident, attributable to the complex interaction between transverse and impinging flows within the apparatus. Finally, a comparison with internal heat transfer correlations is conducted using the data from Florschuetz [1]. Measurement uncertainty was assessed and estimated to be approximately 7% for velocity and ranging from 3% to 10% for Nusselt number.

scholarly journals Experimental Determination of Stator Endwall Heat Transfer

1989 ◽  
Author(s):  
Robert J. Boyle ◽  
Louis M. Russell
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Test Section ◽  
Electrical Power ◽  
Exhaust System ◽  
Ambient Air ◽  
Reynolds Numbers ◽  
Inlet Velocity ◽  
Turbine Vane

Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.

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