The fluid induced forces of the clearance flow in canned motor reactor coolant pump(RCP)and their effects on the rotordynamic characteristics of the pump are numerically and experimentally analyzed in this work. A transient computational fluid dynamics(CFD)method has been used to investigate the fluid induced force of the clearance. A vertical experiment rig has also been established for the purpose of measuring the fluid induced forces. Fluid induced forces of clearance flow with various whirl frequencies and various boundary conditions are obtained through the CFD method and the experiment. Good agreement is found between the experiment and the simulation, which indicates the validity of the CFD method. Results show that clearance flow brings large mass coefficient into the rotordynamic system and the direct stiffness coefficient is negative under the normal operating condition. The rotordynamic stability of canned motor reactor coolant pump does not deteriorate despite the existence of significant cross-coupled stiffness coefficient from the fluid induced forces of the clearance flow.
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