Unsteady Simulation of Film Cooling Flow From an Inclined Cylindrical Jet

Film cooling is extensively used to provide protection against the severe thermal environment in gas turbine engines. Most of the computational studies on film cooling flow have been done using steady Reynolds-Averaged Navier-Stokes (RANS) calculation procedures. However, the turbulent stress field is highly anisotropic in the wake region of the coolant jet, and the inherent unsteadiness of the coolant jet-crossflow interactions may have important implications in the cooling performance. In this paper, a computational investigation about the unsteady behavior of jet-in-crossflow applications is performed using DES. Detailed computation of a single row of 35 degree round holes on a flat plate has been obtained for a blowing ratio of 1.0 and a density ratio of 2.0. Firstly, time step size, grid resolution tests have been conducted. Comparison of the time-averaged DES prediction with the measured film cooling effectiveness shows that DES prediction is reasonable. From present simulations, the typical coherent vortical structures of the jet-in-crossflows can be seen. The unsteady physics of jet-in-crossflow interactions and a jet liftoff in film cooling flows have been explored.