Experimental investigation on the near-field character of film cooling with 30 deg injection from a row of holes on a convex surface

The flow fields near the exits of a row of film cooling holes on a convex surface have been measured extensively. The data measured include the wall static-pressure distribution, the velocity vector, and the film cooling effectiveness. The measurements show that the injection process increases disturbances considerably in the vicinity of the holes. Further downstream, the recirculation zone induced by the mainstream around the jets is still strong. Due to the wall curvature, the film jets have better attachment to the wall than to the flat plate for M less than 1.0. For M greater than or equal to 1.0, however, film jets 'separate' from the wall near the injection holes. Far downstream (X/D greater than 10), the disturbances caused by the jets will decay, and the three-dimensional features will gradually be diminished because of the lateral diffusion of the jets. The present results suggest that the optimum injection rate is about 0.5.