The effect of particle mass concentration on the motion characteristics of particles in a helical-bladed multiphase pump

The helical-bladed multiphase pump demonstrates significant advantages in transporting complex media. However, the presence of solid particles complicates the fluid–structure interaction mechanism, posing challenges to studying solid–liquid two-phase flow within the pump. This research focuses on a self-developed three-stage helical-bladed multiphase pump, employing numerical simulation with experimental validation, to systematically investigate the effect of particle mass concentration (Cm = 1‰, 5‰, and 1%) on particle motion characteristics. The results indicate particle velocity distribution follows similar trends under different Cm conditions. In the impeller flow passage, the circumferential velocity of particles increases significantly while axial velocity changes marginally. Upon entering the guide vanes, circumferential velocity decreases, whereas axial velocity increases. The absolute velocity rises axially along each impeller stage but declines axially in each guide vane stage. As Cm increases, particle backflow intensifies, leading to aggravated flow blockage in the reflux zone at the first-stage impeller inlet. Under high-concentration conditions, particles aggregate into clusters within the flow passage, elevating collision probability. Particle distribution shifts from low-speed to medium-speed regions: dispersed at low Cm but concentrated toward medium-speed zones at medium-to-high Cm. Particle collision frequency rises with Cm, with increased proportions of collisions against the shroud and hub but decreased proportions against blades. The total particle–wall contact force escalates with higher Cm, with impeller-wall forces exceeding guide-vane-wall forces. In the guide vane region, contact forces distribute as blades > shroud > hub. These findings elucidate the kinetic characteristics of solid particles, providing a basis for the optimal design of multiphase pumps.