Abstract: To study the hydrodynamic characteristics of surface piercing propeller under natural ventilation condition, the numerical simulation on the unsteady gas-liquid two-phase flow field of the standard model 841B was performed by solving RANS equation and combining it with the VOF method and using sliding mesh technique. The results show that the calculated values of thrust coefficient KT and torque coefficient 10KQ are in good agreement with the experimental data; especially near the design point, the errors of both are within 5%. The air cavity develops downstream in spirals in the wake field; the diameter of the spiral first increases and then decreases; finally, the spiral cavity gradually disappears. The forces/moments acting on the surface piercing propeller under small immersion condition are very large in horizontal and vertical directions. The wake flow field of surface piercing propeller is bounded by the free surface. The velocity in the wake field mutates in the free surface. In front of the disk, surface piercing propeller affects the flow field by suction effect; whereas the slipstream effect dominates the flow field behind the disk.

Key words: surface piercing propeller, numerical analysis, hydrodynamic characteristics, naturally ventilated condition