Implementation of Rectangular Vortex Generator Pairs to Improve Film Cooling Effectiveness on Transonic Rotor Blade Endwall

The rectangular vortex generator pairs (RVGPs) are arranged upstream of the film cooling holes to achieve better coolant coverage on the endwall near the pressure-side corner area. The endwall film cooling effectiveness distributions under transonic flow conditions are numerically calculated for the single RVGP and double rows of RVGPs cases. At first, the effects of three geometrical parameters (i.e., the distance between RVGP and cooling hole, height of RVGP and attack angle of RVGP) on endwall film cooling effectiveness are studied with a single hole and RVGP at different mainstream inlet Reynolds numbers and blowing ratios. Then, the double rows of RVGPs are applied to further enhance the overall film cooling effectiveness on the blade endwall. The results show that the implementation of RVGPs significantly enhances the film cooling effect on transonic blade endwall at a pressure-side corner area. With the increase of RVGP height, the lateral coolant coverage on the endwall corner area is improved. However, by decreasing the distance between the vortex generator pair and cooling hole, the film cooling effectiveness downstream of the cooling holes is increased. The attack angle of RVGP mainly affects the shape of coolant spreading on endwall surface. The RVGP with optimum dimensions and arrangement is able to suppress the coolant from lifting off the endwall and increase the coolant diffusion near the endwall. Compared with no vortex generator case, the area-averaged film cooling effectiveness on endwall with double rows of RVGPs is improved by 13.16%.