低速轴流压气机叶尖非定常流动试验

利用动态压力传感器对一低速轴流压气机转子的叶顶间隙流场进行详细的试验测量，通过对信号特征的分析，对压气机节流过程中叶顶间隙的非定常流动发展演变规律进行了研究。结果表明：压气机完全失速时，叶尖存在一以46.5%转子转速周向传播的失速团；节流过程中，叶尖前缘处的动态压力信号中存在非定常波动的特征频率带，其变化规律与叶顶流场压力非定常波动的能量迁移有关；随着压气机流量减小，叶顶泄漏流影响区域向前缘移动，失速团在叶顶前缘附近产生，并向尾缘方向扩展，最终覆盖叶片全部弦长；近失速工况时，叶顶间隙相邻通道内泄漏流相互作用，造成通道中的低压区“一前一后”交替分布从而形成一个空间上周期约2个叶片通道的扰动波。

Test of unsteady flow in the tip clearance of low speed axial flow compressor

The flow field in the blade tip clearance of a low-speed axial compressor rotor is measured in detail using high frequency dynamic pressure sensors. The study of the development of the unsteady flow in tip leakage when the compressor throttles to stall has been carried out by analyzing the signal characteristic. The results show that there is a stall cell in the tip clearance and it rotates along the circumferential direction by 46.5% of rotor speed when the rotor gets stalled. When the compressor throttles, a characteristic frequency band appears and it changes according to the energy transformation of unsteady pressure fluctuations in the leading edge of the blade tip. With the flow mass decreasing, tip leakage flow moves forward to the leading edge. A stall cell arises near the leading edge and extends to the trailing edge, eventually covers the whole blade chord length; under the condition of being near stall, low pressure areas in the tip clearance exhibit a "front-back" alternative distribution in channels due to the interaction of the tip leakage flow in adjacent channels. Finally, a disturbance wave forms in the circumferential direction, and its scale is about two blade channels.