不同油膜力模型转子系统的非线性动力学分析

Nonlinear dynamical analysis of rotor-bearing system by nonlinear models of different oil film force

采用有限元法建立实际200MW汽轮发电机组低压段转子-轴承系统非线性动力学方程,应用固定界面模态综合法对其进行降维计算,使系统由原来的112个自由度降为现在的8个自由度,从而显著地提高了数值计算分析的效率.采用Lung-Kutta法对降维后非线性动力学方程进行计算,模拟和比较了转子在椭圆瓦和修正圆瓦油膜力模型作用下发生油膜失稳的典型特征,并采用打靶法计算其Floquet乘子,利用Floquet理论分析转子升速过程运动状态和分岔类型.

The nonlinear dynamical model of the low-pressure rotor-bearing of the 200MW turbine set system is established by FEM,by the fixed-interface component mode synthesis procedure,which is presented in this paper.The number of degrees of freedom is reduced sharply from 112 to 8,and computing efficiency is increased remarkably.The nonlinear dynamical model which reduced dimensions is presented,and the Lung-Kutta method is applied to solve the equation of motion.The typical characteristics of oil film instability of the low-pressure rotor-bearing system is simulated and compared by reduction method which is supported on column and ellipse nonlinear models of oil film force.The state of motion and type of the bifurcation are analyzed by Floquet numbers is which computed by the shooting method during the speed ascending process.