环形压气机叶栅内部严重分离流动的实验研究

Experimental investigation on strongly separated flow in an annular compressor cascade

流动分离是关系到叶轮机械运行安全性和经济性的重要流动现象。为了进一步揭示这一复杂流动现象的特性和物理模型，该文应用激光Ｄｏｐｐｌｅｒ测速仪和七孔气动探针对一环形压气机叶栅在大攻角下的流道内部和流道出口的流场进行了实验研究。得到了流动严重分离情况下的流场速度、湍流度、湍流应力、总压损失及静压等重要流场参数的分布和分离区的形态。实验结果揭示： 在分离流动中粘性分离和惯性分离并存； 分离后的流场呈现出主流、剪切流和分离涡流三区共存的特征，其中速度剪切层对叶栅特性产生显著影响； 在分离边界附近，流动参数变化剧烈，可作为判定分离边界的依据。

Separated flow is a very important phenomenon related with operation safety and economy of turbomachines. In order to understand the characteristics of this complicated phenomenon, a strongly separated flow in an annular compressor cascade at large incidence was investigated using Laser Doppler Velocimeter (LDV) and 7 hole pneumatic probe. The velocity, total pressure loss, turbulence intensity and turbulent stresses were obtained. The results indicate that both inertance and viscouse separation appear simultaneous in the separation region. The whole separated flow field consists of a main flow region, shear speed layer and “dead region”. The shear speed layer has great influence on the performance of the cascade. There are great changes of the flow parameters at the separated flow boundary, which can be used as evidences to determine the separated flow boundary.