Abstract: To investigate the non-axisymmetric flow in centrifugal compressor internal caused by the asymmetric structure of the volute，the combined experimental and numerical methods(Turbulence model choosing S-A model) are used. The results show that the perturbing pressure wave caused by the high static pressure zone of the volute propagates to the upstream in off-design conditions，which brings the non-axisymmetric flow in the compressor. The non-uniform degrees of the static pressure distribution of the volute in the large flow conditions(0.40kg/s) are more obvious than those of the small flow conditions(0.26kg/s). The strong disturbance pressure wave of the impeller outlet can be transmitted to the circumferential position of the impeller inlet about 180°. In the small flow conditions，the circumferential non-uniform degrees of the radial and tangential velocity of the gas flow through the diffuser are more significant. In the large flow conditions，the air flow fluctuations at volute inlet are more obvious. The blade loading distribution and its fluctuations are also affected by the the non-axisymmetric flow. The loading fluctuations of the main blades in the large flow conditions are mainly affected by the blade pass frequency，but in the small flow condition，they are mainly influenced by the two times of the blade pass frequency.

Key words: Centrifugal compressor；Non-axisymmetric flow；Mass flow；Load

摘要： 为探求离心压气机蜗壳周向不对称结构引起的内部非轴对称流动现象，采用实验和数值模拟(湍流模型为S-A模型)相结合的方法进行研究。结果表明:非设计工况下蜗壳高静压区域产生的扰动压力波向上游逆向传播，使压气机内部出现非轴对称流动。大流量工况(0.40kg/s)下蜗壳静压的不均匀程度比小流量工况(0.26kg/s)更明显，叶轮出口较强的扰动压力波可以逆向传播到叶轮进口大约180°的周向位置。流经扩压器的气流径向和切向速度的周向不均匀程度在小流量工况下较为显著，但大流量工况下蜗壳进口气流随时间的波动程度更明显。叶轮内部的非轴对称流动特性对叶片载荷分布及其波动形式产生影响，大流量工况下主叶片表面载荷波动主要受基频影响，而小流量工况下主要受2倍频的影响。

关键词: 离心压气机；非轴对称流动；流量；载荷