Numerical study on rotordynamic coefficients of the seal of molten salt pump

Abstract

Molten salt pump is applied to pump high-temperature molten salt as the primary coolant of a molten salt reactor. The pump, generally a vertical rotor system, suffers from radial force generated by the liquid seal component, and the rotordynamic characteristics of the pump are affected considerably. In this paper, the rotordynamic coefficients of the tooth-on-stator liquid seal in molten salt pump are studied. The flow in the seal region is simulated using computational fluid dynamics technique. Parameters of the inlet loss and the pre-swirl at the inlet region of the seal are calculated. The coefficients of resistance and the wall parameters are obtained from the simulation results by data fitting method. The rotordynamic coefficients are analyzed based on the bulk-flow model of liquid seal. The rotordynamic characteristics, with and without the liquid seal, of the objective molten salt pump are inspected. The first critical speed of the rotor is found to increase. Harmonic analysis shows that the pump, being sensitive to unbalance force though, can operate safely under its design specifications.