Objectives This study aims to investigate the influence and mechanism of cup structure on the hydrodynamic performance of surface piercing propellers.

Methods Based on RANS method and combined with volume of fluid (VOF) method and sliding mesh method, a numerical simulation is carried out on the 841-B surface piercing propellertogether with its cup structure modified propellers under natural ventilation conditions. On the basis of verifying the effectiveness of the numerical simulation method, the trailing edge angle is adjusted based on the dichotomy method to change cup structure of the benchmark surface piercing propeller, and a series of propellers were obtained for simulation calculation and research.

Results The research shows that the change of cup structure has a significant impact on the thrust and torque of the surface piercing propeller, but has a relatively small impact on the efficiency. Enlarging the cup structure allows more water to be attached to blades when it comes out of the free surface, resulting in increased waves and droplet splashing behind the propeller.

Conclusions The research method and research results can provide reference for the design of surface piercing propellers.