In order to investigate the flow-induced vibration in the impeller clearance of centrifugal pump, and make the rotordynamic prediction of the centrifugal pump rotor system, a rotordynamic force model is established which is indispensable to the impeller-rotor system dynamics analysis. The coefficient in the dynamic force model is solved by quasi-steady CFD solution. Multiple quasi-steady solutions of an eccentric three-dimensional model at a series of relative spin velocity yield the rotordynamic forces at different whirl frequency ratios, and a second-order least-square fitting of the rotordynamic forces generates the skew-symmetric stiffness, damping, and mass matrices. Based on the work, the finite element method is applied to establish the model of turbo pump impeller-rotor system. The phenomenon of the fluid oscillation and some typical features are explained from the perspective of oscillation fluid mechanics. The results show complicated frequency characteristics presents in the turbo pump rotor vibration due to the exciting forces generated by shroud leakage flows.
A coupling vibration model of multi-stage pump rotor system based on FEM
