压气机叶顶流动不稳定性试验和数值研究

为了研究大叶顶间隙下压气机的流动失稳演化过程和物理机理，以某单级轴流压气机试验台为研究对象，利用布置于机匣壁面的动态压力传感器测量叶顶流场的脉动特征，利用全通道数值模拟获得与流场失稳发展相关的非定常流动细节。结果表明：随着流量减小压气机内部流动经历了稳定状态、旋转不稳定性和旋转失速3个阶段，叶顶泄漏涡的两种临界行为与不稳定性模式的转变有关。当叶顶泄漏涡移动到相邻叶片尾缘时，在与相邻叶片的干涉作用下开始随时间振荡，导致了小尺度的扰动沿周向传播，即旋转不稳定性。在近失速工况下，叶顶泄漏涡与主流交界面超过叶片流道进口平面，导致前缘溢流，并伴随着前缘径向涡的周期性产生、周向迁移和衰减。此时，前缘径向涡沿周向几乎呈均匀分布，构成了有序传播的扰动。随着压气机被进一步节流，前缘径向涡的有序传播被破坏，形成了局部聚集的分布特征，从而产生了局部堵塞更强、熵更高的失速团。

Experiment and numerical investigation on tip flow instabilities of compressors

To study the tip clearance flow instability of evolution and the physical mechanism of the compressor, a single stage axial compressor experimental rig was taken as the research object. Using the dynamic pressure sensors in the casing wall, the oscillating characteristics of tip flow field were acquired. The unsteady development of flow details was obtained by full channel calculations. It was found that with the decrease of the flow rate, the internal flow of the compressor went through three phases: steady state, rotating instability and rotating stall. The two pivotal activities of the tip clearance vortex were related to the transformation of the instability mode. When the tip clearance vortices propagated to the trailing edge of the neighboring blade, it began to fluctuate under the interference with the neighboring blade, resulting in small scale disturbance propagating along the circumference, that was, rotational instability. In near-stall state, the interface between tip clearance vortices and incoming flow exceeded the inlet of the blade channel, leading to leading edge overflow, which was accompanied by periodic production, circumstantial migration and attenuation of leading edge radial vortices. At this time, the leading edge radial vortices were almost uniformly distributed along the circumferential direction, which constituted the organized propagating disturbance. However, as the flow rate further reduced, the organized propagation of the leading edge radial vortex was destroyed, forming the distribution feature of local aggregation, leading to the stall cells with stronger local blockage and higher entropy.