Effects of vortex generators on endwall film cooling in a turbine vane

Film cooling is widely applied on endwalls in high-performance gas turbines to guarantee the safety and endurance of the engines. Micro ramps are employed to optimize the flow and thermal performance in internal and external cooling designs. In the current investigation, flat-surface film cooling at the blowing ratio of 1.0 and the density ratio of 2.0 is investigated with and without the micro ramp by LES. The result shows that the micro ramp effectively enhances the cooling performance by creating the ACRVP, drawing the coolant toward the wall and enlarging the film coverage. Mean and instantaneous vortical structures are analyzed. Endwall film cooling with micro ramps is studied with high and low mass flow ratios (MFR). The cooling effectiveness of the micro ramp case is 89.9% higher than the baseline case when MFR is high, while 16.3% higher than the baseline when MFR is low. Micro ramps are more effective for endwall film cooling with high MFR. The cooling effectiveness of the region in the middle of the passage improves when applying the micro ramps. In the region upstream of the leading edge, cooling performance deteriorates due to the interaction of the horseshoe vortex and the micro ramps.