Large eddy simulation of film cooling with vortex generators between two consecutive cooling rows

Film cooling approaches are widely applied in modern high-performance turbine engines to improve thermal efficiency. In the current film cooling investigation, vortex generators of delta winglets and the micro ramp installed between two consecutive cooling rows are studied by large eddy simulation (LES). Time-averaged and instantaneous results present the film cooling effectiveness distributions and vortical structure systems in the flow field. It is indicated that film cooling effectiveness is enhanced significantly when applying delta winglets and the micro ramp. An anticounter-rotating vortex pair (anti-CRVP) is generated by the vortex generators, which suppresses the coolant lift-off, weakens the strength of the detrimental counter-rotating vortex pair (CRVP), and enlarges the spanwise coolant coverage. Comparisons of the two vortex generators show that the micro ramp introduces stronger anti-CRVP than that evolved from the delta winglets. For the case without vortex generators, it is observed that the upstream CRVP merges with the downstream one weakening the cooling performance. The effects of vortex generators on the upstream shear layer vortices are examined. Temperature distributions of delta winglets and the micro ramp are discussed to improve the durability when applying them in gas turbine engines.