Effect of symmetrical compound-angle in combined-hole film cooling

Due to high turbine inlet temperatures in modern gas turbines,film cooling technique was used to provide thermal protection for turbine components from being damaged by hot combustion gases. combining two round-hole of film cooling is a better way to enhance the film cooling effectiveness. in the present work,a group of simulations consists of 27 cases using combined-hole unit with opposite compound-angle were carried out. the objective of this work is to find a good arrangement of combined-hole film cooling which produce better film cooling effectiveness. effect of different blowing ratio,m with combination of different distance between two holes in mainstream direction,lod,and compound-angle,γ1/γ2 of film cooling hole were considered. as observed,lateral coverage was spread wider as the compound-angle and blowing ratio increase. while increasing lod produces an insignificant results. however,increasing blowing ratio also resulting drastic decrease of film cooling effectiveness at further downstream. in the present study,area average film cooling effectiveness were determined to evaluate the general film cooling effect of different arrangements. based on the area coverage,m = 1.5 shows an uncertain results for all arrangements. an early separation,spread and lift-off cause the different results at higher blowing ratio. the combination of the lateral distance of the two holes with their compound-angles for the highest film cooling effectiveness is different at different blowing ratios. © 2006-2016 asian research publishing network (arpn). all rights reserved.