不同来流条件下旋转对气膜冷却的影响

Effect of rotation on film cooling under different inflow conditions

大涡模拟考察了旋转状态来流条件对单孔平板气膜冷却的影响,气膜孔沿流向倾斜30°,气膜出流的雷诺数为2 600,吹风比为0.5,计算了静止和旋转数为0.02时气膜冷却的流动和换热,对比两种主流进口条件下旋转对气膜冷却的影响。计算结果表明:(1)均匀来流条件下,旋转主要使发夹涡结构产生非对称分布,裹挟气膜向高半径方向偏转;(2)充分发展的来流条件下,旋转使来流边界层内产生湍流结构,淹没了射流进入主流时产生的发夹涡,引起更强烈的射流扩散,增大了气膜覆盖范围,降低了气膜冷却效率的峰值;(3)旋转通过改变来流边界层内的湍流结构对气膜冷却的影响更显著。

Large eddy simulation was performed to investigate the influence of inflow condition on the film cooling over flat plate has 30° streamwise inclined hole.The Reynolds number at the jet exit was 2 600,and the blowing ratio was 0.5.The flow and heat transfer without rotation and with streamwise rotating number 0.02 were calculated,and the effect of rotation on film cooling under different inflow conditions was compared.Numerical results showed that the most significant influence of rotation on film cooling was the asymmetric distributions of turbulence structure and spanwise deviation of the film when the inflow was uniform.As the inflow became fully developed,rotation induced turbulence structures in the boundary layer of inflow.The resultant near wall streak submerged hairpin structure and induced more intensively diffusion of the jet.Thus the coverage of the film was enlarged and the peak of film cooling effectiveness was reduced.Such comparison showed that the indirect influence of rotation on film cooling by changing the flow structures in the boundary layer of inflow was more significant than the direct rotational effect.