密度差和速度比对单排孔气膜冷却效率的影响

采用传热传质类比的方法研究主射流密度差和速度比对单排孔平板气膜冷却效率的影响.密度比为1时射流为空气,密度比为1.5和2.0射流为异质气体,射流与主流的夹角为35°,孔间距为3倍的气膜孔直径.结果表明:当速度比较小时,射流在被保护壁面上的铺展由扩散控制;当速度比较大时,铺展由对流控制.在较低速度比条件下,随着吹风比的增大,横向和纵向的铺展都增加,有效保护范围面积增加;高速度比条件下,射流的再附点随着动量比的增大而更向下游.

Influence of density ratio and velocity ratio upon the cooling effect of flat panel film

An investigation was conducted to explore the influence of density ratio and velocity ratio of mainstream/injectant upon the cooling effect of flat plane film using heat-mass transfer analogy.The injectant is air in the case of density ratio of 1.0,or heterogeneous gas in the case of density ratio of 1.5 and 2.0.The inclined angle between injectant and mainstream is 35° and the hole spacing is 3 times film hole diameter.The results indicate that,the spreading of injectant is controlled through the protected wall surface for a low velocity ratio,and controlled by convection for a high velocity ratio.With the increase of mass flux ratio,the transverse and longitudinal spreading could be expanded,thus increasing effectively the protective range;the reattachment point will move towards the downstream with the increase of momentum ratio under high velocity ratio.