Numerical simulation of hydrodynamic performance of pump-jet propulsor with serrated trailing-edge duct under different working conditions

Pump-Jet Propulsors (PJPs) have excellent propulsion performance, but the duct makes the internal flow and vortex distribution of PJP more complex. This work presents a serrated modification of the duct trailing-edge of the rear-stator PJP. A Suboff submarine is used to provide wake for PJP, and the propulsion performance and flow field of PJP in self-propelled state are analyzed. In addition, the hydrodynamic coefficients and vorticity fields of two PJPs in oblique flow are compared. The results indicate that the serrated structure can reduce the vorticity magnitude behind the duct, accelerate the shedding of PJP tailing vortex. In direct flow, the higher the inflow velocity, the better the effect of the serrated structure on weakening the wake vortex, which can reduce the vorticity by up to 52.4%. However, the propulsion efficiency of the modified PJP is reduced, but it is within 3%. In oblique flow, the hydrodynamic coefficient and propulsion efficiency of the two PJPs are significantly reduced, and the efficiency of the modified PJP is better than that of the original PJP. The larger the inflow angle, the more obvious the effect of the serrated structure on weakening the wake vortex, and the smaller the loss of propulsion performance.