The numerical simulation for pump-jet propulsors is based on the solution of the Reynolds-Averaged Navier-Stokes (RANS) equations using a two-layer realizable k- model for turbulence closure. The computational domain is discretized into block-structured hexahedral cells. To establish a reliable simulation model, the numerical uncertainties are evaluated according to the procedure recommended by the 28th International Towing Tank Conference (ITTC). Three sets of grids, with a uniform refinement ratio, are generated for a generic pump-jet propulsor at model scale using the grid generator ICEM CFD 17.2, and the flow simulations are carried out using the software package STAR-CCM+. The tip-clearance flow features are numerically investigated for varied thickness and rake profiles of the sections close to the rotator tip. It is shown that the tip geometry has significant influence on the tip vortex.