Effect of Blade Number on Tip Vortex Cavitation of Propeller

Abstract

Tip vortex cavitation not only impacts the hydrodynamic performance of a propeller but also results in vibrations, noise, and erosion. In this study, the effect of blade number on propeller tip vortex cavitation is investigated using computational fluid dynamics (CFD) methods. Numerical simulation is performed regarding four model propellers with blade numbers varying from one to four. These propellers have the same blade geometry as the E779A propeller. Large eddy simulation (LES) and the Schnerr–Sauer cavitation model are used to solve tip vortex cavitation with local mesh refinement according to the spiral tip vortex trajectory. The hydrodynamic performance and tip cavitation of the propellers are solved and analyzed to reveal the fluid mechanism of tip vortex formation. The effect of blade number on wake velocity and wake vorticity is discussed. Numerical analysis showed that the increase in blade number leads to a reduction in the thrust and torque of a single blade, although the total thrust and torque of all blades increased. The present study takes new insights to the suppression of tip vortex cavitation, which benefits propeller design.

Keywords

• marine propeller
• blade number
• tip vortex cavitation
• streamlines