雾滴冷却对压气机边界层分离流动的影响研究

Effect of Water Spray Evaporative Cooling on Boundary Layer Separation in a Compressor Blade

采用欧拉-拉格朗日坐标系对喷雾减温过程进行数值研究,研究喷雾条件下NASA stage 35的流场特性,以及雾滴冷却对边界层分离的影响,探究对边界层分离产生的黏性损失。结果表明,喷雾冷却使流场进口质量流量增加和温度降低。雾滴的蒸发使流体组份发生变化,流场的运动黏度增加,导致边界层分离延迟和边界层厚度变薄。在干空气条件下边界层在25%弦长发生分离。喷雾使边界层移动至29%弦长发生分离。尽管雾滴冷却下边界层分离产生的黏性损失增大,但是边界层分离延迟和变薄对叶型损失起主导作用,喷雾冷却工况下叶型损失减小3.68%。

A numerical study of the spray cooling process has been carried out using the Eulerian-Lagrangian coordinate system to investigate the flow field characteristics of NASA Stage 35 under spray conditions and the effect of droplet cooling on boundary layer pair separation,and to investigate the viscous losses resulting from boundary layer pair separation.The results show that spray cooling leads to an increase in mass flow rate and a decrease in temperature at the inlet of the flow field.As the drops evaporate,the fluid composition changes and the kinematic viscosity of the flow field increases,delaying boundary layer separation and reducing boundary layer strength.Boundary layer separation occurs at 25% chord length under dry air conditions.Spraying moves the boundary layer to 29% chord length where separation occurs.Although viscous loss from boundary layer separation increases under droplet cooling,thinning of the boundary layer separation plays a dominant role in lobe loss,and lobe loss decreases by 3.68% under spray cooling.