跨声速压气机转子旋转失速现象的非定常模拟

为研究跨声速压气机转子失速机理,全周非定常数值模拟了某跨声速压气机单转子的失稳过程。结果表明:该转子由叶尖Spike扰动诱发旋转失速。在小流量稳定工作状态,压气机转子叶尖区域存在"旋转不稳定"(Rotating Instability,RI)流动现象。压气机节流过程中,转子进出口的流量降低,叶尖区流场非定常波动幅值增大。近失速状态时,RI扰动团的典型流场结构"径向涡"在叶尖区域形成堵塞,导致相邻叶片前缘间歇性地出现溢流现象。随着压气机进一步节流,转子叶尖的负荷达到极值,叶片通道尾缘逆压力梯度过大,出现倒流。尾缘倒流的出现又进一步增加通道内的堵塞,最终形成Spike扰动。失速先兆对应的流场结构是沿叶片前缘额线向相邻叶片压力面周向运动的"径向涡"结构。

Unsteady simulation of rotating stall in a transonic compressor rotor

To investigate the mechanism of the stall inception of transonic compressor rotor,an annulus unsteady numerical simulation is performed.Results show that the stall inception of this rotor is spike-type."Rotating instability"(RI)occurs in the tip region when the compressor is operating in the low mass flow region.During the compressor's throttling,the mass flow rate through the rotor decreases,and the amplitude of the tip vortex oscillation increases significantly.Under near stall condition,the "radial vortex"of the RI cells causes large blockage in the tip region,leading to a spillage of tip-clearance flow to the adjacent blade passage ahead of the rotor leading edge intermittently.When the compressor is throttled further, the blade loading exceeds its maximum,and the higher static pressure pushes the fluid originating from the tip-clearance re-gion of one blade to move across the blade passage into the neighboring passage by passing around the trailing edge.When these flow events (spillage of tip-leakage flow at the leading edge and tip-clearance backflow at the trailing edge)occur at the same time,spike disturbance is generated.The formation of the stall inception is the "radial vortex",which moves cir-cumferentially along the leading edge line.