Effect of partial blockage inside film hole on film cooling characteristics

Numerical investigations were performed to study the effects of partial blockage inside discrete holes on coolant jet flow and film cooling characteristics over a flat plate from a row of inclined holes, under the blowing ratios of 0.3-1.5 and blockage ratios of 0.1-0.5. The influences of blockage ratio, blockage position and blowing ratio on adiabatic film cooling effectiveness were revealed. The results in parameter range show that the partial blockage located at the leading edge near film jet exit is beneficial for suppressing the motion of kidney vortex pair, resulting in enhancement of the adiabatic film cooling effectiveness, especially under higher blowing ratio and higher blockage ratio cases. The partial blockage located at the trailing or lateral edges near the film jet exit weaken the adiabatic film cooling effectiveness under higher blockage ratio cases. Compared to the corresponding case of partial blockage located near the film jet exit, the partial blockage located at the film jet inlet or middle position has less impact on the film cooling.