Large Eddy Simulation of Film Cooling With Swirling Coolant Flow

LES (Large Eddy Simulation) of a film cooling with a swirling coolant jet has performed for a circular hole at the blowing ratios of M = 0.5 and 1.0. For the LES of film cooling flows, a film-hole model based on a RFG (Random Flow Generation) technique was proposed to simulate turbulent fluctuating flows at the exit plane of film cooling hole as a boundary model. As a result, film cooling with a swirling coolant jet is confirmed to be effective to reduce net heat transfer from the hot gas to the wall at given uniform temperature conditions by about 6% and 12% at the blowing ratio of M = 0.5 and 1.0, respectively, compared to nonswirling cases. In a swirling film coolant jet case at M = 1.0, penetration of coolant jet is suppressed. It seems that one of the two jet core regions is pressed against the bottom wall by the primary swirl of the coolant jet itself, and this seems to prevent the detachment of the film coolant from the wall. In addition, the proposed film-hole model for LES was validated by the comparison of predicted center-line film effectiveness with a known experimental result.