Research on the excitation force and cavitation performance of a pump-jet propulsor in ice blockage flow

With the accelerated development of polar regions, the stable operation of pump-jet propulsors (PJPs) in ice blockage flow has become a critical challenge. This paper establishes a numerical model of the internal flow channel of a PJP with ice blockage. By combining an Improved Delayed Detached Eddy Simulation method and the Schnerr-Sauer cavitation model, the study systematically investigates the influence mechanisms of ice blockage distance (L/D_r = 0.1∼0.5) on the hydrodynamic performance, excitation forces, cavitation evolution, and flow field of the PJP under two cavitation numbers: σ_n = 3.0 (cavitation inception) and σ_n = 1.5 (critical collapse). The results indicate that both the overall and rotor hydrodynamic coefficients increase with larger L/D_r and higher σ_n. At σ_n = 1.5, the increase in thrust coefficient K_T from L/D_r = 0.1 to 0.5 is 6.45%, which is greater than the 4.09% increase observed at σ_n = 3.0. The interquartile range of excitation forces decreases as L/D_r increases, with σ_n = 3.0 presenting a higher risk of transient impact at closer distances. In ice blockage flow, PJP exhibits multiple cavitation types, including ice-induced cavitation and rotor blade cavitation. At σ_n = 1.5, cavitation appears as sheet-like and cloud-like distributions, whereas at σ_n = 3.0, it is mainly composed of discrete small cavities. Ice-induced vortex couples with rotor and stator vortex systems, significantly altering the evolution of the flow field. The findings can provide theoretical support for vibration suppression and anti-cavitation design of propulsion systems.