Experimental Study of Effects of Coriolis Force on Flow in a Rotating Deffuser

为了研究二次流、科里奥利力稳定性（或不稳定性）和逆压梯度对低展弦比旋转扩压器内流动的耦合影响，测量了压力、时间平均和波动速度分量。本实验研究的结论如下：(1)随着角速度的增加，吸力侧边界层的发展得到促进，而压力侧边界层的发展由于上下壁面边界层的二次流动而受到抑制。最终，由于逆压梯度、二次流和稳定性的耦合作用，充分发育的缓动边界层只与吸力侧壁面分离，而由于二次流和不稳定性的耦合作用，完全发育的缓动边界层不与压力侧壁面分离，但二次流效应可能强于不稳定性效应。(2)迎面流一旦与吸力侧壁面分离，由于二次流和稳定性的共同作用，分离后的流型是稳定的。角速度的变化对扩散器中高度的平均速度和湍流强度分布几乎没有影响。流动大致分为两个区域，压力侧的通流（射流）和吸力侧的分离流（尾迹）。(3)在逆流与通流之间的剪切流区，在相同夹角下，随着角速度的增加，湍流强度减小，这是由于稳定化作用抑制了湍流剪应力的产生。

To investigate the coupled effects of secondary flow, stability ( or instability ) due to Coriolis force, and adverse pressure gradient on the flow in a rotating diffuser of low aspect ratio, pressure, time-mean and fluctuating velocity components were measured. Conclusions reached as a result of present experimental study may be summarized as follows :(1) As increasing angular velocity, the boundary-layr development is promoted on the suction side and is suppressed on the pressure side due to thje secondary flows arising in the top and bottom wall boundary layrs. Eventually, the fully developed and retarded boundary layr separates only from the suction side wall due to the coupled effects of adverse pressure gradient, secondary flow and stability, while never separates from the pressure side due to the coupled effects of secondary flow and instability, but the secondary flow effect may be stronger than the instability effect,(2) Once the oncoming flow is separated from the suction side wall, the separated flow pattern is steady due to the combined effects of secondary flow and stability. The change ofg the angular velocity has little ro no effect on the mean velocity and turbulence intensity profiles at the diffuser mid-height. The flow is divided approximately into two regions, a through-flow ( jet ) on the pressure side and a separated flow ( wake ) on the suction side. The separated flow region with reverse flow is strabilized substantially,(3) In the shear flow region between the reverse flow and the through-flow, the turbulence intensity decreases with increasing the angular velocity at the same included angle because the production of turbulent shear stress is suppressed due to the stabilizing effect.