非设计工况下离心叶轮内湍流场的LDV测量

LDV Measurements of Turbulent Flow Field in a Centrifugal Impeller at Off-Design Flow

利用激光多普勒测速仪(LDV)对后弯闭式离心叶轮内部气流在非设计工况下的流动进行了实验测量。对比描述了大于和小于设计流量时叶轮流道回转流面上主流速度的分布特点,径向流面上的速度矢量图更清晰地说明了不同进口条件导致流道内气流流动产生分离的位置、强度以及发展的差异。二次流矢量图表明流量的改变影响了离心力和哥氏力在流动中的作用,导致在垂直于主流方向引起截然不同的二次涡旋流动。

An experimental investigation of the shrouded centrifugal backswept impeller flow field was conducted at off-design flow by using laser Doppler velocimeter (LDV) and shaft encoder. Measurements of the three-dimensional velocity field at flow rates greater and smaller than design value were acquired. The measurements describe both the throughflow and secondary velocity field along several main planes through the passage. The velocity vector profile clearly documents the different positions, intensity and development of the separation flow when changing the inlet flow rates. The secondary velocity vector plots show that the migration of the secondary vortex across the main flow is influenced by the flow rates which make the centrifugal and Coriolis force changing.