In the paper, the modulation effect of rotor-stator interaction subjected to fluctuating rotation speed is investigated numerically. A quasi-bivariate variable mode decomposition method for analyzing non-stationary flow fields is proposed for the first time. Different from the previous studies, this paper emphasizes the local features of the transient flow field at fluctuating rotation speed. The results show that the impact of fluctuating rotation speed on the impeller force is limited, but it significantly impacts the pressure pulsation at fluctuating frequency. The correlation between amplitude and fluctuation ratio is positive. Meanwhile, the fluctuating rotation speed also induces sidebands centered on the blade passing frequency and its harmonics. The periodic changes in rotational speed lead to frequency and amplitude modulation of pressure pulsations. The magnitude of the instantaneous frequency and amplitude increases as the fluctuation ratio grows. The change in pressure field is well synchronized with the rotational speed, while the change in velocity field lags behind the rotational speed. The variation of pressure field with rotational speed is mainly attributed to two aspects. One is the flow structure at the fluctuating frequency, and the other is the instantaneous component of the flow structure at blade passing frequency.

在本文中，数值研究了受波动转速影响的转子-定子相互作用的调制效应。首次提出了一种分析非平稳流场的准双变量变模态分解方法。与以往的研究不同，本文强调了脉动转速下瞬态流场的局部特征。结果表明，脉动转速对叶轮力的影响有限，但对脉动频率下的压力脉动影响显着。振幅与波动率呈正相关。同时，波动的转速也会引起以叶片通过频率及其谐波为中心的边带。转速的周期性变化导致压力脉动的频率和振幅调制。瞬时频率和幅度的大小随着波动比的增加而增加。压力场的变化与转速同步较好，而速度场的变化滞后于转速。压力场随转速的变化主要归因于两个方面。一个是脉动频率下的流动结构，另一个是叶片通过频率下流动结构的瞬时分量。压力场随转速的变化主要归因于两个方面。一个是脉动频率下的流动结构，另一个是叶片通过频率下流动结构的瞬时分量。压力场随转速的变化主要归因于两个方面。一个是脉动频率下的流动结构，另一个是叶片通过频率下流动结构的瞬时分量。