A canned motor cooling structure for nuclear main pumps for small reactors is proposed. Its characteristics are that the primary and secondary cooling water inlet is located above, and the casing between the stator end cavities is wound with a spiral heat exchanger. The thermal rated condition is the steady state before the test of the secondary water cutoff for 5 minutes that must be completed for the new product of the canned motor. The inversion study of the thermal and flow field distribution law under this condition is very important for the thermal safety of the motor. First, the nuclear main pump was selected as the research object (the motor, the spiral tube heat exchanger and the main pump connection below), and the geometric model of the calculation domain was established. Then, using the finite volume method, the flow field and temperature field of the three-dimensional rotating clearance were simulated under the rated thermal condition, and the friction pressure drop value and the temperature distribution characteristics of the cooling water and solid at the stator and rotor clearance were obtained based on the thermo-physical properties parameters of primary and secondary water at high pressure. The results show that the error between the temperature simulation results at the measuring point and the test data is less than-4.88%, and the results are more accurate. In the middle of the motor where the heat exchanger is located, the temperature of the secondary water, the motor casing, and the clearance water basically rises linearly from top to bottom along axial direction, which provides a reference for the design of the water-cooling circulation circuit of similar motors. © 2022 Editorial Department of Electric Machines and Control. All rights reserved.
