Optimization of Cold-Start Strategies for Seawater Pumps in Polar Ice Conditions

Seawater pumps operating in polar low-temperature, ice-laden environments are subject to a high risk of start-up failure, in which the transport, accumulation, and blockage of ice crystals within the pump play a critical role in determining start-up reliability. To investigate the cold-start behavior of seawater pumps under polar ice conditions, a transient multiphase numerical model incorporating ice–water two-phase coupling effects is developed. The model is employed to systematically examine the influences of the motor acceleration index and the impeller–volute clearance on ice-crystal blockage risk and start-up response characteristics.For a representative operating condition with an ice-crystal volume fraction of 10%, the transient internal flow and phase distribution evolution are simulated using an Eulerian–Eulerian multiphase framework, and the numerical predictions are validated against experimental results. The results demonstrate that the acceleration index primarily affects the start-up stabilization time and peak torque by regulating the rotational speed ramp-up rate and the unsteady evolution of the flow field during the start-up process; however, its contribution to improving ice-crystal passability is relatively indirect. In contrast, the impeller clearance significantly reshapes ice-crystal transport pathways by modifying leakage-flow intensity and flow connectivity, thereby providing a more direct and sustained mitigation of localized high-concentration accumulation and blockage risks. These findings offer quantitative guidance for the optimization of start-up strategies and the design of anti-blockage structures for seawater pumps operating in polar regions.