Film cooling experiments with sonic injection were conducted to investigate the effects of the number of the injection holes

the mass flow ratio

and the hole spacing on the film cooling effectiveness. The mainstream was obtained by the hydrogen-oxygen combustion

entering the experimental section at a Mach number of 2.0. The nitrogen with ambient temperature was injected into the experimental section at a sonic speed. The measured mainstream recovery temperature was approximately 910K. The mass flow ratio was regulated by varying the nitrogen injection pressure. The experimental results show that for the investigated cooling surface

the cooling effectiveness increases with the increase in the number of the injection holes with other parameters held constant. For a fixed cooling configuration

the cooling effectiveness increases with the increase in the mass flow ratio. Different from the subsonic film cooling

the optimal mass flow ratio is not observed. When the hole spacing is less than 4

no obvious difference is observed on the cooling effectiveness and lateral uniformity. With the mass flow ratio increasing further

this difference becomes much smaller. The shock wave also has an effect on the cooling effectiveness. Downstream the incident point of the shock wave

the cooling effectiveness is lower than that in the case without the shock wave.