Effect of profiled endwall on heat transfer under different turbulence intensitie

The efficiency of the gas turbine engine has been enhanced by improving aerodynamic performance and reducing heat load through control of secondary vortices according to the first-stage vane endwall configura-tions. In this study, the heat transfer features of flat and profiled endwalls were investigated under different turbulence intensities. Experiments were conducted under a fixed turbine-vane exit Reynolds number of 300,000 and Mach number of 0.15 on both geometries. The test specimen was scaled up 3.23 times based on the actual gas turbine vane geometry. The profiled endwall configuration was optimized considering the combustor outlet/ exit geometry. Five control points were set for the vane geometry, and the minimum aerodynamic loss at the vane exit plane was determined as an objective function. As the turbulence intensity is increased, the heat transfer is increased on both endwall geometries. However, the intensity of the horseshoe vortex was signifi-cantly reduced with the profiled endwall compared with the flat endwall. Consequently, the area-averaged Sherwood number on the profiled endwall was about 25.8% (under the low turbulence intensity) and 19% (under the high turbulence intensity) lower than those of a flat endwall case, respectively.