Large-eddy simulation of SUBOFF wake effect on the propeller tip vortex cavitation inception

Propeller cavitation inception is often promoted by non-uniform wake, yet the underlying mechanisms remain insufficiently understood. To address this issue, wall modeled large-eddy simulation (WMLES) coupled with a Lagrangian bubble model is employed to investigate cavitation inception in a coupled system consisting of a model-scale SUBOFF and a seven-blade highly skewed propeller. Both the measured and predicted results show that cavitation inception is most likely to occur at the blade tip when the propeller passes through the 12 o’clock position. This behavior is closely related to the non-uniform wake generated by the SUBOFF, particularly the sail. Regarding the pressure within the tip-vortex (TV) core, the sail wake not only induces the maximum TV strength at the 12 o’clock position, but produces large vortex core pressure fluctuations through enhanced vorticity stretching from merging co-rotating tip vortices. In terms of nuclei distributions, the sail wake facilitates the entrainment of nuclei and promotes their preferential growth at the same azimuthal position. Consequently, cavitation inception is most likely to occur at the blade tip when the propeller reaches the 12 o’clock position. The present results provide physical insight into cavitation inception in non-uniform wakes and may support the development of wake-based cavitation control strategies for marine propulsion systems.