Effect of film hole geometry and blowing ratio on film cooling performance

In this paper, four kinds of film holes (cylindrical hole, fan-shaped hole, anti-vortex hole and sister hole) are experimentally and numerically studied to investigate the effect of hole geometry and blowing ratio on film cooling performance and flow structure. The blowing ratio ranges from 0.3 to 2.0, the density ratio is 1.065 and the mainstream Reynolds number is 38664. In the experiment, the steady-state Thermoehromie Liquid Crystal (TLC) is applied to obtain the film cooling effectiveness. The numerical investigation is performed to analyze the flow structure and counter-rotating vortex pair (CRVP) intensity. Experimental results show that the sister hole demonstrates best cooling performance with blowing ratio from 0.3 to 1.5. The sister hole provides better cooling performance than anti-vortex hole. While the fan-shaped hole performs better at high blowing ratios and it achieves best at blowing ratio of ZO. Numerical simulation indicates that for the anti-vortex hole and sister hole, the application of side holes can decrease the main hole CRVP intensity and weaken the mixing between the main hole CRVP and mainstream, which increases cooling performance. The coolant interaction between side holes and main hole of the sister hole is stronger than that of the anti-vortex hole.