Prediction of hydrodynamic performance of pump jet propulsor considering the effect of gap flow model

There is a strong gap flow exists between the pump rotor tip and the inside of the duct of the pump jet propulsor. To predict the hydrodynamic performance of a pump jet propulsor more accurately, considering the influence of fluid viscosity in the gap area, a gap flow model suitable for a pump jet propulsor is proposed. Through an analysis of the hydrodynamic performance of the pump jet propulsor, it is determined that it is optimal for the gap height to be 0.98–1.0 times of the complete gap height, Additionally, it is verified that the flux coefficient (CQ) range of 0.8–0.84, which can accurately simulate the energy loss of the fluid at the gap flow, is reasonable. Moreover, through a comparative analysis of the hydrodynamic performance, pressure, and circulation distribution of the pump jet propulsor, it is found that, when the influence of the gap flow model is considered, the wall pressure and circulation distribution of the rotor blade and duct are more consistent with the calculation results of viscous flow. In addition, the introduction of the gap flow model only improves the prediction accuracy of the hydrodynamic performance of the pump jet propulsor.