Propeller boss cap fins on efficiency and wake instability mechanism

In this study, Reynolds-averaged Navier–Stokes and large eddy simulation methods are used to analyze the propeller boss cap fins (PBCF) parameter matching and wake field dynamics characteristics of propeller. The new PBCF optimizes the pressure field behind the hub cap by interfering with the wake flow, reducing torque, increasing thrust, and improving the propeller efficiency of the optimized PBCF by 2.433%. On this basis, the effects of weakened hub vortex on tip and sheet vortices after installation of PBCF are summarized, and the resulting wake instability is analyzed. After installing PBCF, the weakened hub vortex tended to interact with each other and from clusters. Furthermore, the interaction of the sheet vortices is influenced by the PBCF, and the deformation of sheet vortices changes. In particular, the reduction in the tip vortex to vortex distance after installation of PBCF occurred further downstream. In the far field, the wake field is disrupted and chaotic. It is shown that the installation of PBCF changes the characteristics of wake field and improves the efficiency of propeller.