Design and Experimental Verification of Hubless Rim-Driven Propulsor Consisting of Bearingless Propeller for an Unmanned Underwater Drone

This paper presents the design and experimental verification of a hubless rim-driven propulsor (HRDP) for an unmanned underwater drone. The bearings of the HRDP are required to rotate and fix the propeller. However, the bearing increases the weight and size of the propulsor. Therefore, this paper proposes a structure in which the rotor of a surface-mounted permanent magnet synchronous motor (SPMSM) and a hubless propeller are combined without the bearings in the rim-driven propulsor. The design procedure of the propulsor is established and the response surface method (RSM) is used to design and optimize the proposed structure. The validity of the HRDP with the proposed structure is verified through simulation results using an electromagnetic field (EF) analysis and computational fluid analysis, and test results using a water tank. Finally, compared to the initial HRDP, the weight of the SPMSM in the optimized HRDP is decreased by 7.3%, and by reducing the required torque by about 19%, power consumption is reduced by about 24.66 W.