Investigation on the influence of gas-ingesting inflow on internal flow characteristics of a waterjet propulsor under steering conditions

To investigate the internal flow evolution of a waterjet propulsor under coupled steering and gas-ingesting conditions, this study establishes a full-passage model based on the shear stress transport turbulence model and an Eulerian–Eulerian multiphase flow framework. Using this model, gas–liquid two-phase flow simulations are conducted for a mixed-flow waterjet propulsor under steering conditions. The results indicate that under gas-ingesting inflow conditions, the performance of the waterjet propulsor exhibits systematic degradation. The flow rate, thrust, and head decrease nonlinearly with increasing steering angle and inlet gas volume fraction, with the flow rate attenuation reaching up to 32.6% and the thrust attenuation reaching ∼55%. Under the influence of the impeller rotation, the gas phase forms a spatially nonuniform distribution, accumulating on the blade surfaces. This results in decreased pressure on the pressure side and increased pressure on the suction side, thereby reducing the blade pressure differential and significantly impairing the impeller’s work capacity. Gas accumulation within the inlet flow passage triggers vortex fragmentation and flow field distortion, increasing the flow nonuniformity. The vortex fragmentation phenomenon induced by the gas phase becomes more pronounced at larger steering angles.