Particle distribution and two-phase flow characteristics of twin-screw pump during solid-liquid transfer

Abstract

The twin-screw pump is a kind of positive displacement machinery with smooth pressure and flow pulsation and strong self-priming ability, which is widely used in the fields of oilfield production, marine engineering, and other fields. However, in the process of conveying liquid-phase media, it is difficult to avoid the inclusion of solid impurities and grit, resulting in wear of the pump casing and rotor, and the pump’s pressurization capacity is reduced or even shut down. At present, the solid-liquid two-phase flow characteristics within the twin-screw pump have not been clarified, which hinders the study of particle wear in the pump. In this paper, a solid-liquid two-phase flow study is carried out on a twin-screw pump through numerical simulation and experimental testing. The distribution of particles with different diameters in the rotor domain with the liquid-phase transport process is explored by simulating the two-phase flow under different differential pressures and particle concentrations. The results show that the particles in the rotor domain are mainly distributed in the region away from the male and female rotor engagement, and the number of particles near the engagement is small but the velocity is higher under the influence of the clearance jets; the elevation of the differential pressure and the particle concentration increase the risk of the particles to collide with the rotor more frequently and at higher velocity; at different particle concentrations, new localized vortices are caused by particle conveying which compared to pure liquid transport, but there are also cases where the original vortices are suppressed. The results will provide a theoretical basis for further research on particle wear characteristics in twin-screw pumps.