Film cooling effectiveness of double-jet film cooling holes was measured using pressure sensitive paint at various mainstream angles of attack (i=-30°

-20°

-10°

0°

10°

20°

30°) on a flat plate

and the flow field obtained by computational fluid dynamics (CFD) was used to analyze the film cooling effectiveness. The dimension less spanwise distance was 0.5

the dismension less streamwise distance was 3; the density ratio was 1.0

and the blowing ratio varied as 0.5

1.0

1.5

2.0. The results showed that

at small mainstream angles of attack (i=-10°

0°

10°)

the film layer attached well with wall because of the anti-kidney vortex pair or the pressing effect in the flow field

contributing to the highest film cooling effectiveness; at large positive angles of attack (i=20°

30°)

the anti-kidney vortex pair degenerated though the coverage area of film was the largest

the film cooling effectiveness became lower; at large negative angles of attack (i=-20°

-30°)

there existed kidney vortex pair

the lateral coverage of the film was limited and the film cooling effectiveness was lowest.