Effects of impeller whirling vibration on the rotor–stator interaction in a centrifugal pump

This study employs the dynamic sliding multi-region and the Reynolds averaged Navier–Stokes to conduct computational fluid dynamics numerical simulations on the centrifugal pump flow characteristics under four forms of impeller whirling vibrations. The influence mechanisms of different whirling forms on the unsteady flow characteristics and rotor–stator interaction are analyzed. Because of assembly errors and non-uniform support stiffness, the centrifugal pump impeller does not undergo simple eccentric rotation. Instead, it exhibits the complex whirling vibration with multiple kinematic characteristics, which has been neglected in previous studies. First, the numerical models of different whirling vibration forms are established to simulate the unsteady flow characteristics. The accuracy is verified using the test bench. Second, the study investigates the influence mechanisms of different whirling vibration forms on the flow characteristics and rotor–stator interaction. The results demonstrate that the rotor–stator interaction can be categorized into small-scale interaction from the single blade and large-scale interaction from the overall impeller under whirling conditions. The additional fluctuations caused by whirling vibration result from periodic variations in the magnitude and direction of the impeller outflow velocity. Under backward whirling, the modulation frequency amplitude of the flow characteristics is greater. This is because the high tangential speed region of the impeller is opposite to the whirling direction, thereby intensifying the unsteady flow characteristics caused by rotor–stator interaction. This study serves as a foundation for vibration and noise control and fault diagnosis of centrifugal pumps.