针对某亚声速轴流压气机转子,采用多通道全三雏数值模拟方法对其预失速性能(即失速起始过程)进行了时间精确的数值模拟。对计算结果进行分析表明,环面高压斑的传播速度及其影响范围与已有的试验测量结果取得了很好的一致性,因此数值模拟合理地揭示出了突尖波产生的流体动力学机制。叶尖分离涡的形成及其在不同通道的传播是流动失稳过程中叶尖流场的主导特征。当叶尖分离涡的强度超过某一临界值,它的尾部会吸附在叶片通道的吸力面上。随着它的尾部向吸力面尾缘移动,它将诱发尾缘反流形成间隙溢流,即形成了“后返前溢”的流动现象,此时突尖渡开始出现。因此,“后返前溢”现象可视为该压气机转子突尖波出现的开端事件。
Pre-stall behavior in a subsonic axial compressor rotor has been investigated by multi-passage three- dimensional time-accurate numerical simulations. The propagation speed of high pressure spot on flow annulus ahead of the rotor and its associated circumferential and radial influencing area agree well with the available experi- mental observations. This demollstrates that the current method captured the flow mechanism of spike emergence reasonably. The dominant feature of tip flow fields during the transition process is the formation of tip separation vortex and its propagation at different tip-passages. Should the strength of tip separation vortex in some passage exceed some critical value, its rear end will stand on the suction side of the blade. The tip clearance backflow from the adjacent passage spilled into the next passage as the rear end of tip separation vortex approached the trailing edge. This phenomenon can be considered as the threshold event of spike emergence for the test rotor.