Study on the solid-liquid two-phase flow characteristics of coolant pumps for energy storage system at different rotational speeds

Coolant pumps are critical for liquid cooling in energy storage systems, regulating coolant circulation through speed adjustments to maintain optimal temperatures. However, particles in the system cause pump erosion, threatening equipment lifespan and system safety. The multiphase flow and erosion characteristics under varying speeds are particularly complex. This study addresses this issue by employing numerical simulations based on the Euler-Lagrange Discrete Phase Model coupled with the Oka erosion model. Validated by experimental results, the research focused on the energy performance of the coolant pump under varying rotational speeds with particle ingress, analyzing particle volume distribution, trajectories, component erosion, and Stokes number variations. The findings indicate that under solid-liquid two-phase flow, increased flow rate and rotational speed reduce the performance of the coolant pump, with a more pronounced decrease in efficiency. At higher speeds, particle volume within the impeller and volute significantly decreases, while impeller trajectories shift towards the pressure side. Additionally, particle entry angles into the volute increase, with centrifugal forces driving particles along its outer edge, while particle ingress into the motor gap increases. Erosion rates and distributions across various components escalate significantly with rising speed. Stokes number analysis reveals that impeller erosion is dominated by inertial forces, causing impact-induced pitting. In contrast, particles in the volute and motor gap exhibit better flow-following behavior due to lower inertia, resulting in strip-like sliding erosion. This research provides valuable insights for improving the operational performance and service life of coolant pumps under solid-liquid two-phase flow conditions.