Abstract: Based on the correction particle motion equation for low particle Reynolds number in the impeller of centrifugal pump，the following features of tracer particles in response to the flow field of centrifugal pump is described mathematically. The particle motions are investigated numerically, and the two aspects of influencing factors on the relative motion between tracer particles and liquid medium are discussed. Based on several kinds of computation model，the effects of each force on the flow following behaviours are comparatively studied, and then the advantages and disadvantages of each model are pointed out. The results show that the neutral suspended particles with the same density as fluid have good ability to follow the fluid motion. The larger density particles only with smaller diameter can follow a certain frequency range of turbulent flow. The radial following feature is more complex than the circumferential one. The following feature of tracer particles is bad at the area of low-speed vortex, especially in the radial direction. The Coriolis force and the centrifugal force caused by rotating impeller strongly influence the following feature of tracer particles, also including the centrifugal force caused by the impeller curved channel. Through understanding and grasping these influencing factors, it will be helpful to choice tracer particles to increase the accuracy of flow measurements by particle image velocimetry in the centrifugal pump.

Key words: Centrifugal pump, Following behaviors, Influential factors, Tracer particles