Abstract：In order to investigate the influence of ship speed on the internal flow characteristics of marine water-jet propulsion, the axial-flow water-jet propulsion is taken as the research object. Based on the software ANSYS-CFX, N-S equation and standard k-ε turbulence model were used to steady numerical simulate the whole basin of water-jet propulsion at rated speed 5 500 r/min and different ship speed. The pressure load on different sections of impeller blade of water-jet propeller at different ship speeds, the change of turbulent kinetic energy on each flow passage component and the distribution characteristics of velocity streamline on different internal sections were obtained. The results show that the variation law of pressure load with speed on the three different sections of 0.1span, 0.5span and 0.9span is basically the same, and the pressure at the blade inlet reaches the peak, and the pressure decreases slightly at the blade outlet. The turbulent kinetic energy increases with the increase of speed. The maximum turbulent kinetic energy at each speed is mainly distributed at the rim. The internal flow of the inlet passage is affected by the rotation of the driving shaft and the curvature change of the bend, which resulting in uneven flow with vortex appears. The vortex is affected by the speed of the ship. At low ship speed, the vortex concentrates on the lower wall of the inlet passage, and at high speed, the vortex concentrates on the upper wall of the inlet passage, and the vortex merge will occur.
