Fluid Dynamics of Film Cooling Investigated by Large-Eddy Simulation

Abstract

High blade temperatures limit the performance of gas turbines. Film cooling is used to lower the blade temperature by ejecting cold gas through holes in the blade surface directly into the boundary layer. The resulting flow configuration is very complex with respect to the geometry and the involved physical phenomena. Numerical simulations of film cooling are mostly done using Reynolds averaged Navier-Stokes (RANS) simulations which by their nature are incapable of capturing the full physics of this problem. Therefore, we investigate this flow by large-eddy simulations (LES) which are able to resolve the essential flow structures and the large-scale turbulence in space and time. For modelling the effect of subgrid scales we use our approximate deconvolution model (ADM).

We aim at simulating film-cooling configurations with an accurately represented geometry, increasing the level of reality step by step. This will allow us to investigate in detail flow regimes (e.g. high temperatures) that are hard to capture with experiments. Although LES need only about one percent of the computational time of corresponding direct numerical simulations (DNS), they still require exceptionally large computing resources.