A coupling vibration model of multi-stage pump rotor system based on FEM

Annular seal is one of the important factors influencing the dynamic vibration property of multi-stage pumps. In order to research the vibration characteristics of multi-stage pumps, a coupling vibration model of multi-stage pump rotor system, including the coupling effects of bearings and short annular seals dynamic coefficients, was developed based on Finite Element Method (FEM) and Lagrange equation. A model rotor was investigated to verify the numerical results of the coupling vibration model. Based on the coupling vibration model, the first critical speeds of the model rotor system were analyzed under different seal drop pressures and radius seal clearances. The experimental results of the model rotor showed good agreement with the calculated results and smaller calculation error compared with the previous model. The calculated maximum error percentage and minimum error percentage using the coupling vibration model were 5.5% and 0.2%, respectively. Most error percentages were between 1%+/-3%. The calculated results show that the coupling model is an effective method for the vibration research of multi-stage pump rotor system.