Hydrodynamic analysis of a rim-driven thruster based on RANS method

Rim-driven thruster is gaining wide attention in applications such as underwater vehicles and low-speed vessels. Literature on the influence of rotating rim and the rim-fixed blades on performance is scanty. In this paper, a rim-driven propeller was modeled with its hydrodynamic performance numerically simulated by a commercial Reynolds-averaged Navier-Stokes equation solver. The influence of rim on the wake field and friction loss was studied by simulations using rims of different lengths. The results show a long rim will increase friction torque slightly and will induce a circumferential velocity to the local flow, which means at blade tip region the relative tangential velocity of inflow to the blade section reduces and the pitch angle increases. Analysis of the pressure contours indicates the rim-driven propeller is easier to cause cavitation problem if directly modified from Ka-series. In addition, a following blade thickness study shows the thin blade has an efficiency advantage over the thick one.