Design and Analysis of the Integrated Motor Cooling System for Shaftless Propeller

In order to deal with the heat dissipation of the integrated permanent magnet motor for a certain shaftless propeller, this paper designs an automatic water-circulation cooling system. The cooling system involves two annular grooves on the inner wall of the duct before and after the blades, the two grooves are connected with the air-gap between the motor stator and rotor to form a cooling passage in which cooling water flows from the rear of the propeller to the front. The performance analysis of the cooling system is a multi-physics problem involving electromagnetic field, flow field, and temperature field. This study combines the finite element method and the finite volume method to simulate and analyze the multi-field coupling problem of the cooling system. Tests of the shaftless propeller prototype are used to prove that the coupling simulation model is accurate and the cooling system is practical. Additionally, the verified simulation model is applied to analyzing the influence of several key factors, such as air-gap flow rate, pouring sealant thermal conductivity, and stator sheath material, on the heat dissipation of the integrated motor. The study made in this paper can provide a reference for developing the same kind of devices.