Effects of Boss Caps and Propeller Boss Cap Fins on Controllable-Pitch Propellers with Varying Pitch Ratios on Open Water Characteristics
摘要
Propeller boss cap fins (PBCFs) on propellers have been shown to reduce the wake effect behind propellers, enhancing both thrust and efficiency. Through numerical analysis, this paper examines the impact of boss caps and PBCFs on the open-water characteristics of propellers. A geometric model of marine propellers is developed by modifying the boss cap of VP1304, commonly known as the Potsdam Propeller Test Case propeller. A steady-state three-dimensional numerical model utilising the shear stress transport k–ω turbulence model is employed for the analysis. The open water characteristics obtained from the numerical simulations align closely with available experimental data. A comparative analysis is performed between propellers with boss caps and those with PBCFs to assess the significance of boss cap geometry and PBCFs in improving propeller efficiency. Accordingly, implementing a vortex diffuser-type boss cap can yield efficiency improvements comparable to those achieved using a more complexly designed PBCF. Thereafter, a propeller open-water test simulation of propellers is conducted with and without PBCFs across four different pitch ratios to investigate the influence of PBCFs on a propeller with variable pitch ratios. This analysis demonstrates the potential of PBCFs to enhance the safe operating regime of controllable-pitch propellers.