Comparison of Predicted and Measured Turbine Vane Rough Surface Heat Transfer

Abstract

Predicted turbine vane heat transfer for a rough surface over a wide range of test conditions was compared with experimental data. Inlet pressures varied between 0.2 and 1 atm., and exit Mach numbers ranged between 0.3 and 0.9. Thus, while a single rough surface vane was used for the tests, the effective roughness in wall units varied by more than a factor of ten. Comparisons were made for both high and low freestream turbulence intensities. Two-dimensional Navier-Stokes heat transfer predictions were obtained using the code RVCQ3D. Results were obtained using both algebraic and k–ω turbulence models. The algebraic model incorporated the Cebeci-Chang roughness model. The k–ω turbulence model accounts for roughness in the boundary condition. Roughness causes turbulent flow over the vane surface. Even after accounting for transition, surface roughness significantly increased heat transfer compared to a smooth surface. The k–ω results agreed better with the data than the Cebeci-Chang model. The low Reynolds number k–ω model did not accurately account for roughness at low freestream turbulence levels. The high Reynolds number version of this model was more suitable at low freestream turbulence levels.