Flow resistance characteristics and mechanism of film cooling holes with ribbed crossflow

In order to find out the effects of internal cooling structures on outer film cooling performance, experimental measurements and numerical simulations have been carried out to investigate the flow resistance characteristics and mechanism of cylindrical holes with coolant crossflow in ribbed channel over a series of crossflow Reynolds number(Re_c=1×10⁵, 5×10⁴) and blowing ratio(M=0.5, 1, 2). The results show that the swirl flow in the hole caused by the crossflow is the main reason for the decrease of discharge coefficient. Flow blockage at hole entrance caused by the rib can further reduce the discharge coefficient. Under the same crossflow Reynolds number, the discharge coefficient increases with the blowing ratio and approaches to a constant value when the blowing ratio increases to 2. Under low blowing ratios(M=0.5 ~ 1), the discharge coefficient decreases with the increase of crossflow Reynolds number. However, the effects of crossflow Reynolds number on the discharge coefficient become smaller with the increase of blowing ratio(M=1 ~ 2).