Experimental research on film cooling characteristics of cylindrical hole and expanding hole on the leading edge

Film cooling characteristics of expanding hole and cylindrical hole on the leading edge were measured using a transient liquid crystal measurement technique considering the influence of curvature.Local distribution characteristics and quantitative relationships of different holes' film cooling effectiveness were analyzed under different average blowing ratios.The results show that:(1) As compared with the cylindrical hole,the expanding hole jet has a larger coverage,the offset angle of the main coverage area is smaller.(2) In different test regions,the average cooling effectiveness of cylindrical hole rises firstly and then decreases with increasing average blowing ratio.In the region between the first and second row of holes,the average cooling effectiveness of expanding hole monotonously increases with average blowing ratio.In the downstream region after the second-row holes,the average cooling effectiveness of expanding hole is basically the same under all average blowing ratios.(3) Within the experimental range,the laterally averaged effectiveness of expanding hole is much larger than that of cylindrical hole.