Dynamic Analysis of Centrifugal Pump Rotors With Fluid-Mechanical Interactions

Abstract

Calculating bending vibrations of centrifugal pump rotors, stability and unbalance response are of major interest. In order to predict the dynamic behavior accurately, one has to take into account the coupling mechanisms between the vibrating shaft and the surrounding fluid. This paper presents a finite-element procedure which includes the fluid forces arising from journal bearings, seals, balance pistons and impeller interactions to the dynamic calculations of turbopumps. The theoretical background is briefly explained and a simple Jeffcott rotor is used to show several effects of these fluid forces. Finally, a real multistage boiler feed pump is calculated and discussed.