NUMERICAL ANALYSIS ON THE HYDRAULIC PERFORMANCE OF THE AUXILIARY IMPELLER IN LARGE CAPACITY CANNED -MOTOR PUMP

A special structure named auxiliary impeller is designed in the large capacity canned-motor pump to improve the performance of inner loop cooling system. The structure is set on the rotor shaft using the center hole as the inlet conduit and four holes perpendicular to the center hole as the blade channels. The auxiliary impeller is driven by the rotor shaft of the motor and functions as a centrifugal pump. The inner coolant circulates in the clearance of the pump under the effect of centrifugal force generated by the impeller. In this paper, the output pressure of the auxiliary impeller at different rotational speeds is investigated by numerical simulation. Three geometric parameters including the diameter of the inlet channel, the diameter of the blade flow channel, and the rotating radius are considered in the research. The pressure drop curves of the auxiliary impeller at different rotational speeds are drawn and a mathematical model is given to interpret it. The results show that both the three geometric parameters have influence on the output performance of the auxiliary impeller, and the diameter of the blade channel and the length of the rotating radius are the primary factors.