Effects of mainstream attack angles on film-cooling effectiveness of double-jet film-cooling

Effects of mainstream attack angles on double-jet film-cooling (DJFC) effectiveness under different blowing ratios (M = 0.5, 1.0, 1.5, 2.0) are investigated experimentally on a flat plate, and the flow field is obtained by simulation. The attack angles (i) are −30°, −20°, −10°, 0°, 10°, 20°, 30° respectively. The spanwise distance (p/d) of DJFC is 0.5, and the streamwise distance (s/d) is 3.0. Effects of density ratios (DR = 1.0, 1.5, 2.5) are also considered. Results show that at small attack angles (i = −10°, 0°, 10°), film-cooling effectiveness is highest at most blowing ratios. At large positive angles (i = 20°, 30°), the film covers a large area and cooling effectiveness is substantial. In addition, density ratio has a strong influence on cooling at these two attack angles. At large negative angles (i = −20°, −30°), the lateral coverage of the film is limited and the cooling effectiveness is very low.