Effect of Dynamic Structure Stiffness on Rotor Characteristics of Vertical Pump

The support structure dynamic stiffness of rotor of vertical circulation pump used in AP1000 nuclear power plant was analyzed with finite element method, and the results demonstrated that the dynamic stiffness value decreased with frequencies and suddenly drop at resonant frequency. Based on this relation result, a contrast modal analysis about three situations which consider rigid bearing stiffness, sliding bearing stiffness and support structure dynamic stiffness respectively were done for the rotor model’s dynamic characteristic. The result demonstrated that the difference between 1st lateral vibration frequency of rotor are not obvious, the frequencies were 28.1,21.7 and 20.2Hz, nevertheless the higher vibration frequency difference between the three situations are obvious. The higher vibration frequencies decreased apparently with the support stiffness considered.