The combined effect of film hole number and diameter on the film cooling were investigated on the rotating blade leading edge by using experimental and numerical methods. The film cooling performance was obtained by pressure sensitive paint technique under rotational condition. To better understand the experimental results, the flow fields obtained from numerical simulation were also analyzed. The effects of hole length-to-diameter ratio (L/d = 2.5/5/7.5), hole number (N = 7/9/10/11/13), hole diameter(d = 0.64∼1.26 mm), Hole to hole pitch, (P/d = 6.3∼9.2) and hole exit area (Ahole/ALE=4 %-14 %) on the film cooling performance are investigated. Five blowing ratios are also employed (M = 0.5 to 2.0). The results indicate that the hole length-to-diameter ratios (L/d = 2.5∼7.5) have a negligible influence on the film cooling effectiveness. Both the film hole number (N = 10/13) and the hole diameter (d = 0.64/0.75 mm) monotonically affect the film cooling performance under each blowing ratios. However, a comprehensive study indicates that there is a significant quadratic correlation between the area-averaged cooling effectiveness and the total film hole exit area for different combinations of hole number and diameter. Meanwhile, there is an optimal film hole exit area on the leading edge and it increases as the blowing ratio or mass flow rate increases.

中文翻译：

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孔径和孔数对旋转叶片前缘薄膜冷却性能影响的综合研究


采用实验和数值方法研究了薄膜孔数和直径对旋转叶片前缘薄膜冷却的综合影响。在旋转条件下，采用压敏漆技术获得薄膜冷却性能。为了更好地理解实验结果，还分析了从数值模拟中获得的流场。研究了孔长径比 （L/d = 2.5/5/7.5）、孔数 （N = 7/9/10/11/13）、孔径 （d = 0.64∼1.26 mm）、孔距 （P/d = 6.3∼9.2） 和孔出口面积 （Ahole/ALE=4 %-14 %） 对薄膜冷却性能的影响。还采用了五种吹塑比（M = 0.5 至 2.0）。结果表明，孔长径比 （L/d = 2.5∼7.5） 对薄膜冷却效果的影响可以忽略不计。在每种吹塑比下，薄膜孔数 （N = 10/13） 和孔径 （d = 0.64/0.75 mm） 都会单调影响薄膜冷却性能。然而，一项全面的研究表明，对于孔数和直径的不同组合，面积平均冷却效率与总膜孔出口面积之间存在显着的二次相关性。同时，前缘有一个最佳的膜孔出口区域，并且随着吹塑比或质量流量的增加而增加。