压气机转子叶尖区域流动特征的观测与分析

为了揭示压气机转子内部真实流动的演化过程并分析其背后的流动机制,采用示迹线显示空气流动的方法对某低速轴流压气机转子流场进行了直接观测,同时结合多通道非定常数值模拟技术分析了转子叶尖区域流动特征及其形成机制.结果表明:叶片上的示迹线直观形象地显示了转子内部复杂流动随压气机工作状态变化的演化过程.即随着压气机转子节流,叶顶间隙泄漏流的轨迹不断向上游移动,到达近失速工况时,泄漏流与来流的交界面与转子叶顶前缘平齐,与此同时转子叶尖吸力面附近出现了大面积的回流,且回流的气体均向叶顶前缘聚集.通过进一步研究发现叶顶间隙区域内泄漏流与主流的轴向动量之比随转子流量系数减小而不断增大是导致泄漏流轨迹前移及叶顶回流区扩大的物理机制.

Observation and analysis of flow features in blade tip region of compressor rotor

In order to investigate the evolutionary tendency of the compressor rotor's real rotating environment and explain its associated flow mechanism, the filament traces method was used for flow field visualization in a low-speed axial compressor rotor. And the unsteady multiblade-passage numerical simulations were also carried out to study the flow field characteristic of the blade tip region and its formation mechanism. Based on experimental results, the evolution processes of the complex flow inside the rotor passages were seen clearly as the compressor was throttled towards the stability limit. The results show that as the rotor's mass flow is reduced, the trajectory of blade tip leakage flow moves upstream towards the leading edge of the blade tip. When the compressor is operating near stall condition, the interface between the main flow and the tip leakage flow is nearly parallel to the rotor leading edge plane at the blade tip. Meanwhile the large backflow region appears on the suction side of the blade tip, and the backflow is found to be collected at the leading edge near the blade tip. And the further research shows that the axial momentum ratio of the tip leakage flow to the main flow in the clearance region increases as the flow coefficient decreases, serving as a mechanism for the forward movement of the tip leakage flow and the growth of the backflow region.