Experiments were made by using supersonic

high temperature gas in a cylindrical pipe as the mainstream and nitrogen at normal temperature as the injection medium to determine the rules of discrete holes supersonic gas film cooling.Mainstream Mach number was 2

and injection Mach number varied from 1 to 3 . Results show that the mass flow of the injection is the most important influential factor.Film cooling effectiveness that could be fitted into a correlation equation is enhanced greatly along with the increase of blowing ratio or diameter of the injection hole

and the Mach number of the injection has little effect on it.Injection with angle 30 degree shows better effectiveness than the tangential injection at downstream distance far from the hole

but worse effectiveness dose by the hole.