Large eddy simulation of pulsed film cooling with vortex generators

Film cooling is an effective approach to cool the blades in a high-performance gas turbine engine. Pulsed and unpulsed film cooling with vortex generators pair (VGP) are studied using large eddy simulations. The Strouhal number of the sinusoidal coolant pulsation is 0.25, and the blowing ratio for the unpulsed cooling is M = 1.0. Time-averaged and instantaneous results indicate that both the upstream installed VGP and the dynamic pulsing effect significantly improve cooling effectiveness. The passive method of VGP enhances the cooling effectiveness by generating an anticounter-rotating vortex pair (anti-CRVP), which accelerates the coolant reattachment, expands the spanwise coolant coverage, and weakens the strength of the detrimental counter-rotating vortex pair (CRVP). For the unpulsed cooling, an uncooled gap region exists between the trailing edge of the hole and the onset of the coolant reattachment. The gap is offset when applying the pulsed cooling. Detailed vortical structures show the generation and evolvement of anti-CRVP and CRVP. The transportation of the separated wakes in the pulsed cooling is presented. It is observed that the strength of CRVP is weakened in the pulsing process. The interaction of the VGP introduced anti-CRVP and the separated coolant wakes is discussed. (c) 2021 Elsevier Ltd. All rights reserved.