The effects of blowing ratio at M=10 and 20 on downstream flow field single film cooling hole with compound-angle orientations have been investigated experimentally.It is found that a pair of counterrotating vortices

one of which is strong and another is weak

were observed in the downstream region of jet exit.The hole with a fan-shaped angle of 0° or 15° was oriented so that its angles with respect to the test surface are 60° in a stream/normal plane projection

and 30° or 45° in a spanwise/normal plane projection.Contours of longitudinal velocity show asymmetric kidney shape.The fan-shaped hole effectively decreases the strength of longitudinal vortex and increases the spreading of jet so that the film cooling effectiveness would be much greater than that found in the downstream of a circular hole.