Assessment of Source Term and Turbulence Model Combinations for Film Cooling in Turbines

Abstract

Modern gas turbines require an active cooling system with fluid taken from the compres- sor to withstand the high turbine inlet temperature. CFD is a useful tool to estimate the effects of different cooling configurations on the blade aerodynamics and the thermal loads. However, this usually requires resolving every cooling hole with a high number of grid cells. To reduce the computational cost of such simulations, a reduced order model using source terms was implemented in TRACE. Different variants are tested on a cylin- drical and a laid back fan shaped cooling hole to address issues with accuracy and grid dependency known from the literature. Additionally, two different turbulence and heat flux model combinations are compared to each other. Overall, a differential Reynolds Stress Model with an algebraic heat flux model combined with the simplest approach to modeling film cooling holes, introducing a constant source term at the wall, provided the best results for the considered geometries and blowing ratios. The different strategies to improve the predictions were only able to provide a benefit for some of the cases, while usually having a detrimental effect in other cases.