Effect of injection hole geometry on film-cooling performance of turbine blades under different free-stream turbulence conditions and blowing ratios

The film cooling method using various geometric hole shapes has played a crucial role in the cooling of high-pressure turbine blades. ANSYS CFX software was employed to simulate film cooling on turbine blades. The problem was analyzed using the Reynolds-Averaged Navier–Stokes (RANS) equations with the SST k-ω turbulence model and low y⁺ values (less than 2). The results show that improving the hole geometry consistently enhances the cooling effectiveness on turbine blades compared to cylindrical holes. This study was conducted under three different free-stream turbulence intensities (Tu = 3.6%, 7.5%, and 11%) and four different blowing ratios (M = 0.025, 0.05, 0.075, and 0.1). The results indicate that, at the same blowing ratio, the cooling effectiveness of the improved rectangular inlet and outlet hole is significantly higher than that of the cylindrical hole under all turbulence levels. Specifically, at a low blowing ratio of M = 0.025, the improved hole’s peak effectiveness is over 73% higher than that of the cylindrical hole. At a higher blowing ratio of M = 0.1, the peak effectiveness of the improved hole exceeds that of the cylindrical hole by 86%