DOWNSTREAM FLOW AND HEAT TRANSFER OF A FILM COOLING FLARED HOLE INCLINED AT 60°

The flow field and heat transfer downstream from a film cooling flared hole has been investigated experimentally.The jet hole with a flared angle of 15° or 30° was oriented so that its streamwise injection angle with respect to the test surface is 60°.A delicate five-hole probe and thermocouple were applied to measurement of the three-dimensional flow field and the heat foil method was used to obtain surface heat transfer distribution.Experiments indicate that the longitudinal velocity contours in the downstream boundary layer of the flared exit have three basic forms.With increasing area of the jet exit,the flared hole increases the spreading of the jet and decreases the strength of the longitudinal vortex appreciably,in result the film cooling effectiveness much greater than that of a circular hole.For the high blowing ratio and big flared angle,the flared hole jet still produces a successful heat protection downstream and high cooling effectiveness.