转子叶顶间隙泄漏流轨迹前移的动力学机制

为了揭示压气机转子节流时其叶顶间隙流动的演变趋势及其形成机理,选取某亚声速轴流压气机转子为研究对象,采用多通道非定常数值计算方法对其内部流场进行了全三维数值模拟.结果表明:随着压气机转子流量减少,主流轴向动量减小,而在叶顶间隙两侧压力梯度和二次泄漏流的共同作用下,叶顶间隙泄漏流的轴向动量却不断增大,导致叶顶间隙区域内泄漏流与主流的轴向动量比不断增大,从而推动叶顶间隙泄漏流与主流的交界面不断向上游移动,这意味着叶顶间隙泄漏流在叶顶通道内造成的流动阻塞区不断扩大,正是叶顶间隙泄漏流相对于主流的增强造成的叶顶流动阻塞区不断扩大最终导致了该压气机转子进入失速状态.

Dynamics mechanism of tip leakage flow trajectory movement in rotor

In order to uncover the evolutionary tendency of the tip clearance flow in a subsonic axial-flow compressor rotor as well as its associated flow mechanism, the unsteady three-dimensional multi-passage numerical simulations were carried out to investigate the flow field of the compressor rotor. The computational results show that as the compressor rotor's mass flow decreases, the axial momentum of the incoming flow reduces, and that of the tip leakage flow increases under the impact of the pressure gradient between the pressure side and suction side of the tip clearance block combined with the secondary leakage flow, thus increasing the axial momentum ratio of the tip leakage flow to the approach flow in the clearance region. The consequence is a movement of the interface between the incoming flow and the tip leakage backflow toward the leading edge of the rotor. As the strength of the axial reversed flow is increased from design status to near stall, the flow blockage zone in the rotor tip region becomes more severe and moves further upstream, which plays a role in triggering the compressor stall.