scholarly journals Direct Numerical Simulations of a High-Pressure Turbine Vane

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Andrew P. S. Wheeler ◽  
Richard D. Sandberg ◽  
Neil D. Sandham ◽  
Richard Pichler ◽  
Vittorio Michelassi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Surface Flow ◽  
Surface Heat ◽  
Suction Surface ◽  
Data Set ◽  
Turbulent Dissipation ◽  
Surface Heat Transfer ◽  
Turbine Vane ◽  
Exit Mach Number

In this paper, we establish a benchmark data set of a generic high-pressure (HP) turbine vane generated by direct numerical simulation (DNS) to resolve fully the flow. The test conditions for this case are a Reynolds number of 0.57 × 106 and an exit Mach number of 0.9, which is representative of a modern transonic HP turbine vane. In this study, we first compare the simulation results with previously published experimental data. We then investigate how turbulence affects the surface flow physics and heat transfer. An analysis of the development of loss through the vane passage is also performed. The results indicate that freestream turbulence tends to induce streaks within the near-wall flow, which augment the surface heat transfer. Turbulent breakdown is observed over the late suction surface, and this occurs via the growth of two-dimensional Kelvin–Helmholtz spanwise roll-ups, which then develop into lambda vortices creating large local peaks in the surface heat transfer. Turbulent dissipation is found to significantly increase losses within the trailing-edge region of the vane.

scholarly journals Direct Numerical Simulations of a High Pressure Turbine Vane

2015 ◽  
Author(s):  
Andrew P. S. Wheeler ◽  
Richard D. Sandberg ◽  
Neil D. Sandham ◽  
Richard Pichler ◽  
Vittorio Michelassi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Surface Flow ◽  
Surface Heat ◽  
High Pressure Turbine ◽  
Suction Surface ◽  
Data Set ◽  
Surface Heat Transfer ◽  
Free Stream Turbulence ◽  
Turbine Vane

In this paper we establish a benchmark data set of a generic high-pressure turbine vane generated by direct numerical simulation (DNS) to resolve fully the flow. The test conditions for this case are a Reynolds number of 0.57 million and an exit Mach number of 0.9, which is representative of a modern transonic high-pressure turbine vane. In this study we first compare the simulation results with previously published experimental data. We then investigate how turbulence affects the surface flow physics and heat transfer. An analysis of the development of loss through the vane passage is also performed. The results indicate that free-stream turbulence tends to induce streaks within the near wall flow, which augment the surface heat transfer. Turbulent breakdown is observed over the late suction surface, and this occurs via the growth of two-dimensional Kelvin-Helmholtz spanwise roll-ups, which then develop into lambda vortices creating large local peaks in the surface heat transfer. Turbulent dissipation is found to significantly increase losses within the trailing-edge region of the vane.

Experimental Measurements and Modeling of the Effects of Large-Scale Freestream Turbulence on Heat Transfer

2004 ◽  
Author(s):  
A. C. Nix ◽  
T. E. Diller ◽  
W. F. Ng
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbine Blade ◽  
Large Scale ◽  
Surface Heat ◽  
Integral Length Scale ◽  
Length Scale ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Surface Heat Transfer

The influence of freestream turbulence representative of the flow downstream of a modern gas turbine combustor and first stage vane on turbine blade heat transfer has been measured and analytically modeled in a linear, transonic turbine cascade. High intensity, large length-scale freestream turbulence was generated using a passive turbulence-generating grid to simulate the turbulence generated in modern combustors after passing through the first stage vane row. The grid produced freestream turbulence with intensity of approximately 10–12% and an integral length scale of 2 cm (Λx/c = 0.15) near the entrance of the cascade passages. Mean heat transfer results with high turbulence showed an increase in heat transfer coefficient over the baseline low turbulence case of approximately 8% on the suction surface of the blade, with increases on the pressure surface of approximately 17%. Time-resolved surface heat transfer and passage velocity measurements demonstrate strong coherence in velocity and heat flux at a frequency correlating with the most energetic eddies in the turbulence flow field (the integral length-scale). An analytical model was developed to predict increases in surface heat transfer due to freestream turbulence based on local measurements of turbulent velocity fluctuations and length-scale. The model was shown to predict measured increases in heat flux on both blade surfaces in the current data. The model also successfully predicted the increases in heat transfer measured in other work in the literature, encompassing different geometries (flat plate, cylinder, turbine vane and turbine blade) and boundary layer conditions.

Experimental Measurements and Modeling of the Effects of Large-Scale Freestream Turbulence on Heat Transfer

2006 ◽  
Vol 129 (3) ◽  
pp. 542-550 ◽  
Author(s):  
A. C. Nix ◽  
T. E. Diller ◽  
W. F. Ng
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Turbine Blade ◽  
Large Scale ◽  
Surface Heat ◽  
Integral Length Scale ◽  
Length Scale ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Surface Heat Transfer

The influence of freestream turbulence representative of the flow downstream of a modern gas turbine combustor and first stage vane on turbine blade heat transfer has been measured and analytically modeled in a linear, transonic turbine cascade. High-intensity, large length-scale freestream turbulence was generated using a passive turbulence-generating grid to simulate the turbulence generated in modern combustors after passing through the first stage vane row. The grid produced freestream turbulence with intensity of approximately 10–12% and an integral length scale of 2cm(Λx∕c=0.15) near the entrance of the cascade passages. Mean heat transfer results with high turbulence showed an increase in heat transfer coefficient over the baseline low turbulence case of approximately 8% on the suction surface of the blade, with increases on the pressure surface of approximately 17%. Time-resolved surface heat transfer and passage velocity measurements demonstrate strong coherence in velocity and heat flux at a frequency correlating with the most energetic eddies in the turbulence flow field (the integral length scale). An analytical model was developed to predict increases in surface heat transfer due to freestream turbulence based on local measurements of turbulent velocity fluctuations and length scale. The model was shown to predict measured increases in heat flux on both blade surfaces in the current data. The model also successfully predicted the increases in heat transfer measured in other work in the literature, encompassing different geometries (flat plate, cylinder, turbine vane, and turbine blade) and boundary layer conditions.

A Transient Liquid Crystal Method Using Hue Angle and a 3-D Inverse Transient Conduction Scheme

2000 ◽  
Author(s):  
Mingjie Lin ◽  
Ting Wang
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Surface Heat ◽  
Heat Transfer Surface ◽  
Transfer Coefficients ◽  
Data Set ◽  
Surface Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Hue Angle ◽  
Transient Conduction

Various transient liquid crystal methods have been widely and routinely employed to measure surface heat transfer coefficients. Typically, the heat transfer surface was modeled as a one-dimensional, transient heat conduction over a semi-infinite surface to retrieve information of the surface heat transfer coefficients. To satisfy the theoretical initial and boundary conditions, inconvenient and/or complex designs are required. Frequently, the conditions are not exactly satisfied. To resolve these issues, an approach of measuring heat transfer coefficients coupling the transient liquid crystal method with a 3-D inverse transient conduction scheme was developed and was applied to a nonuniform heat transfer surface produced by arrays of impinging jets. The present method utilized the hue-angle method to process the color images captured from the liquid crystal color play. Instantaneous temperature readings from embedded thermocouples were utilized for in-situ calibration of hue angle for each data set. The convective heat transfer coefficient results were obtained by performing a 3-D inverse transient conduction calculation over the entire jet impingement target surface and the substrate. The results of average heat transfer coefficients agreed well with previous experimental results of point measurements by thermocouples.

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