Enhancement of film cooling effectiveness using upstream ramp

Film cooling is widely used in high-performance gas turbines to reduce surface heat flux and placing a ramp at the upstream of film cooling hole improves film cooling effectiveness. In this work, RANS based numerical simulations were carried out for a flat surface having two rows of injection holes and an upstream ramp. The parameters which were considered in this computation were different blowing ratios (M=0.6, 1.0 and 1.6) and upstream ramp angles (α=14° to 24°). Surface effectiveness was increased with increase in angle of upstream ramp and blowing ratio but further increasing these parameters decreased the effectiveness. The downstream of the second row hole effectiveness was more than that of the upstream hole for high blowing ratios in case of without ramp. Copyright © 2012 by ASME.