Numerical Investigation of Cavitation Flow Characteristics in a Hydrodynamic Levitated Micropump with Eccentric Rotation

Abstract

In this study, the anti-cavitation performance and cavitation flow characteristics in a hydrodynamic levitated micropump were investigated based on numerical simulation and experiment. The cavitation characteristic curves and the development process of cavitation in the levitated micropump was firstly analyzed. Special emphasis was put on the effects of eccentricity on the anti-cavitation performance. The results show that as the eccentricity increases, the critical cavitation number gradually decreases, indicating that the eccentric rotation is beneficial to improve the anti-cavitation ability of the levitated micropump. The coupling effects between the radial force on the impeller and cavitation were also numerically studied. With the decrease of cavitation number, the radial force on the impeller gradually declines at first, then has a sudden increase and finally reduces with fluctuation. The drop of the radial force will lead to the decrease of eccentricity, resulting in the deterioration of cavitation further. In addition, the unsteady pressure pulsation was analyzed. The predominant frequencies of pressure pulsation are the blade passing frequency (BPF) and the harmonic frequency of BPF under both noncavitation and critical cavitation. Under critical cavitation, the amplitude of BPF has a drop, while the amplitude of low frequency less than BPF becomes larger.