A phenomenon called rotating instability was rarely reported in a centrifugal compressor, although some associated discussions can be found in axial compressors. This paper presents a numerical investigation on the unsteadiness of the tip leakage flow and rotating instability in an isolated centrifugal compressor impeller. A three-dimensional, unsteady full annuls simulation is performed under three different operating conditions. The tip leakage flow unsteadiness at the impeller inlet and inside the impeller passage is detected by the pressure fluctuation. During the throttling process, the temporal and spatial propagation characteristic of the tip leakage flow unsteadiness under the near stall operating condition is revealed based on the wavelet analysis, Fourier transform, and dynamic mode decomposition. Furthermore, the relationship between the tip leakage flow unsteadiness and the rotating instability is also discussed. The results show that the pressure fluctuation mainly concentrates in the tip region at the near stall operating condition, which indicates the occurrence and circumferential propagation of tip leakage flow unsteadiness. The circumferential propagation of the tip leakage flow unsteadiness induces a significant circumferential rotating pressure wave with a wave number of 9 and approximately 48.2% of the rotational speed of the impeller. The characteristic frequency of the tip leakage flow unsteadiness agrees well with the dominant mode frequency of rotating instability. Therefore, the tip leakage flow unsteadiness is assumed to be responsible for the rotating instability. During the throttling process, the formation and development of the rotating instability at near stall operating condition can be divided into three stages based on signal analysis: prior to rotating instability, generation and development, and rotating instability.

尽管在轴流式压缩机中可以找到一些相关的讨论，但在离心式压缩机中很少报道一种称为旋转不稳定的现象。本文对孤立离心压缩机叶轮中叶尖泄漏流的不稳定性和旋转不稳定性进行了数值研究。在三种不同的操作条件下进行三维非稳态全环模拟。通过压力波动检测叶轮入口和叶轮通道内叶尖泄漏流动的不稳定性。在节流过程中，基于小波分析、傅里叶变换和动态模态分解，揭示了近失速工况下叶尖泄漏流不稳定的时空传播特性。此外，还讨论了尖端泄漏流不稳定与旋转不稳定之间的关系。结果表明，在接近失速工况下，压力波动主要集中在叶尖区域，表明叶尖泄漏流不稳定的发生和周向传播。叶尖泄漏流不稳定的周向传播引起显着的周向旋转压力波，波数为 9，叶轮转速约为 48.2%。尖端泄漏流不稳定的特征频率与旋转不稳定的主模式频率非常吻合。因此，假设尖端泄漏流不稳定是旋转不稳定的原因。在节流过程中，