Effects of duct parameter on pump-jet propulsor unsteady hydrodynamic performance

This work aims to investigate the effects of duct parameter on the open water performance of pump-jet propulsor. Five duct parameters are considered, including the length-diameter ratio, the incidence angle, the shrinkage ratio of duct inlet, the expansion ratio of duct outlet and the tip clearance ratio. Based on the mesh verification, a brief analysis of the PJP unsteady propulsion performance is first presented. The duct parameters are thoroughly studied, focusing on the open water performance, thrust fluctuation, the pressure field and its fluctuation, the velocity field and vortices. The results indicate that the length-diameter ratio and the expansion ratio of duct outlet have significant effects on open water performance and controlling the vortices. The tip clearance ratio and the shrinkage ratio of duct inlet show slight effects on performance, but the tip clearance flow presents noticeable changes. The incidence angle also has significant impacts on tip clearance vortices but results in more considerable performance changes than tip clearance ratio and shrinkage ratio of duct inlet.