突片形状对气膜冷却效率的影响

Effects of Tab Shapes on Film Cooling Effectiveness

气膜冷却广泛应用于航空发动机热端部件的热防护,为了提高气膜冷却效果,设计了3种突片型式,采用实验的方法对其冷却效果进行了对比研究,结果表明:突片的存在强化了气膜冷却效率,使得气膜冷却效率远高于无突片的气膜冷却效率。吹风比对不同突片作用有所不同,存在一最佳吹风比,但该值随着突片的型式变化。突片的堵塞比对气膜冷却效率有很大的影响,3种突片作用下的气膜冷却效率均随堵塞比的增加而增大。梯形突片的冷却效率明显优于三角形突片和椭圆突片。但突片亦增大了气膜孔的流动阻力,降低了流量系数。

The film cooling is widely used in the thermal protection of aircraft engine.To improve the effectiveness of film cooling,three kinds of tabs are designed,and experimenal results of film cooling effectiveness show that tabs on the film holes can effectively strengthen the film cooling efficiency,which makes the film cooling effectiveness much higher than that without tabs.The effects of blowing ratios on film cooling is different for different tabs,and there exists an optimal blowing ratio which is different for different tabs.The blockage ratio of tabs has a great influence on film cooling effectiveness.The three kinds of tabs keep the same film cooling characteristics that the film cooling effectiveness increases with the increase of the blockage ratio.Trapezoidal triangle tab is obviously better than the other two kinds of tabs.However,the discharge coefficient of the film hole is largely decreased by the tab.