Investigating the effect of blade tip bending (winglet) on efficiency and occurrence of cavitation of a submerged propeller

Cavitation, caused by sudden pressure changes in the flow, increases fuel consumption and reduces marine propeller efficiency. It also affects hydrodynamic noise, excitation forces, and structural integrity, leading to vibration-induced stress and material erosion. In this research, the CFD method has been used to investigate the effect of the geometrical parameters of the end bending of the propeller (winglet) on the total volume of cavitation, with the aim of reducing its destructive effects and improving the efficiency of the propeller. Single-phase (liquid) and two-phase (liquid and vapor) simulations have been conducted using STAR-CCM + software. First, the simulation results of an AU5-50 propeller with various winglets, obtained by combining four winglet geometry parameters, are analyzed using the Taguchi experiment design method. Then, by applying Taguchi optimization, the geometry of the optimal winglets is extracted and simulated in relation to three outputs: efficiency, total volume of cavitation, and the combined output of efficiency and total volume of cavitation. According to the obtained results, the optimal design of the propeller winglet can reduce the total volume of cavitation formed on the propeller by 8.48%, while simultaneously improving the efficiency of the propeller by up to 1.24%.