内通道交错横流对气膜冷却效率的影响

采用数值模拟研究了内通道横流对气膜流动和冷却特性的影响,参数变化范围:横流比Cr=0.39,0.78;吹风比Br=1,2;气膜孔长径比l/d=4,8.计算结果表明:①内通道冷气横流使得气膜孔内气流产生较强的涡旋,使得冷气射流的流动具有明显的非对称特征,引起表面气膜冷却效率分布不均;②横流比对表面气膜冷却效率分布影响较大,横流比越大,气膜孔内涡旋越强烈,气膜冷却效率分布越不均匀;③长径比较大时,气膜孔内气流较为规整,气膜覆盖区域较为狭小,气膜冷却效率分布更加不均;吹风比较大时,射流在主流通道上的附着较差,气膜冷却效率较低.

Numerical study of the effect of internal coolant crossflow on film cooling effectiveness

This paper investigated numerically the effect of a coolant crossflow on film cooling effectiveness.Computations were performed to investigate the three-dimensional film cooling flow and cooling effectiveness with two crossflow ratios(Cr=0.39,0.78) and two blowing ratios(Br=1,2) and two length to diameter ratios(l/d=4,8).The results of the present investigation show that there is a profound effect of how the coolant is supplied to the hole on the film-cooling performance in the near hole region,for example,crossflow ratio has great influence on the film-cooling effectiveness of surface,a bigger length to diameter ratio brings about regular flow within film holes,and a bigger blowing ratio leads to poorer adhesion of jet stream and lower film-cooling effectiveness.Therefore,crossflow at the hole entry side has to be taken into account when modeling film-cooling schemes of turbine blades.