多级轴流氦气压气机流动失稳实验研究

Experimental Study of the Instability of the Flow Inside a Multi-stage Axial Flow Type Helium Compressor

利用闭式循环实验台，分别使用氦气和空气工质，对多级轴流氦气压气机的流动失稳进行实验研究。实验结果表明，在不同转速下，氦气压气机的流动失稳呈现出不同的特征：在高转速下，流动失稳呈现出大尺度、高振幅、低频率的喘振特征；在低转速下，流动失稳表现为小尺度、高振幅、高频率的旋转失速特征；而在中间的过渡转速，则表现为大尺度和小尺度扰动同时出现。基于相似准则的空气工质实验所表现的流动失稳特征与氦气工质实验所表现的特征一致，且相应的B参数亦接近，说明流动失稳特征与工质无关，是压缩系统特性的表现。

An experimental study was carried out on the instability of the flow inside a multi-stage axial flow type helium compressor on a closed cycle test rig by using helium and air as the working medium respectively. The test results show that at various rotating speeds ,the instability of the flow inside the compressor in question will display different characteristics：at high rotating speeds, it will assume such surge characteristics as a large scale, high amplitude and low frequency; at low rotating speeds, it will exhibit such rotating stall characteristics as a small scale, high amplitude and high frequency while at the intermediate transient rotating speeds, it will showcase simultaneously its disturbance in both large and small scale. The flow instability characteristics displayed in the test of air as the working medium based on the similarity criteria are in agreement with those displayed in the test of helium as the working medium and the corresponding B parameters are also close with each other, indicating that the flow instability characteristics are irrelevant to the working medium and pertain to the behavior of the compressor system.