Film cooling from two rows of holes with opposite orientation angles: injectant behavior and adiabatic film cooling effectiveness

The present paper is aiming at describing the injectant behaviors from two rows of film cooling holes with opposite orientation angles. Boundary layer temperature distributions were measured in the streamwise normal plane to illustrate the interaction between the injectant from the holes in the upstream row and from the downstream row. Detailed adiabatic film cooling effectiveness distributions were also measured using thermochromic liquid crystal to investigate how well the injectant covers the film cooled surface. Four film cooling hole arrangements were considered including inline and staggered ones. And three blowing ratios of 0.5, 1.0 and 2.0 were studied. At the blowing ratio of 0.5, the injectant is centered near film cooled surface irrespective of hole configurations to show high film cooling effectiveness. When the blowing ratio exceeds unity the injectant tends to lift off from the wall due to the increase of the wall normal momentum. With the inline configuration, not like other configurations, the injectant is still well attached to the wall with the help of the downwash flow formed at the hole exit.