Objective This study aims to investigate the influence and mechanism of a cup structure on the hydrodynamic performance of a surface-piercing propeller.

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

Results Changing the cup structure has a significant impact on the thrust and torque of the surface-piercing propeller, but relatively little impact on its efficiency. Enlarging the cup structure allows more water to be attached to the blades when it emerges from the free surface, resulting in increased waves and droplet splashing behind the propeller.

Conclusion The method and results of this paper can provide useful references for the design of surface-piercing propellers.