Investigation on Shallow Trenched-Hole Film Cooling Effectiveness at Turbine Blade Pressure Side

Abstract

Numerical simulations are performed to investigate the effects of shallow trenches on the adiabatic film cooling effectiveness (ηad) of single row film cooling on the pressure side of a turbine guide vane, under the cascade representative conditions. The mainstream inlet Reynolds number is set as 4×105. A single row of film cooling holes are located at 30% axial chord length at the pressure side. Three shallow trenches with different widths (w/d=2, 2.5 and 3) but have the same depth (0.75d) and a cylindrical film cooling hole are compared in the current study at M= 2.0. The results show that the shallow trenched-hole on the pressure side significantly suppresses lift-off of the secondary flow, and effectively improves the spanwise uniformity of film coverage. Therefore, compared with the conventional cylindrical hole (CH), the shallow trenched-hole shows a significant enhanced film cooling performance at M=2.0. By comparisons, it is confirmed that the shallow trenches with w/d=2 and 2.5 are more pronounced than the shallow trench with w/d=3. While the shallow trench with w/d=2.5 takes a little advantage over the w/d=2.