Nonlinear dynamic stability analysis for a large-scale rotor-bearing system

A reduction calculation method based on fixed interface component mode synthesis is applied to analyze nonlinear dynamic stability of an actual large-scale rotor-bearing system. The reduced motion equations of a 200 MW steam turbine low-pressure rotor bearing and that without reduction are calculated numerically using the Newmark method. The comparison results show that the reduction calculation method can simulate the vibration characteristics of the system very well and remarkably improve the efficiency of calculation. The changing rule of stability of the rotor with eccentricity of the rotor, the clearance-to-radius ratio, the length-to-diameter ratio, and oil viscosity of the bearing is revealed by numerical calculation. The results provide the theoretical basis for analyzing stability in the design and operation processes of this type rotor-bearing system.