Abstract: In order to study the effect of the tabs-ridged located along the upstream edge of declining holes on the film cooling, three types of the film cooling holes with different blockage ratio are designed to study the change of the film cooling efficiency with the blowing ratio and blockage ratio, and the velocity fields near the reattachment are studied by using numerical simulation. The results show that the film cooling efficiency of the film cooling holes with the tabs-ridged is higher than the typical round film cooling holes by 130% at least. The film cooling efficiency is increased as the blowing ratio increases. The film cooling efficiency is highest when the blockage ratio is 0.21. The numerical results agree well with the experimental results. Increase of blowing ratio or blockage ratio improves the spanwise coverage of reattachment area and then the film cooling effectiveness in a definite range.

Key words: Aerospace propulsion system, Film cooling effectiveness, Tabs-ridged