实际机组低压转子—轴承系统非线性动力学

Non-linear dynamical analysis of low-pressure rotor-bearing of actual turbine set system

采用有限元法建立200MW汽轮发电机组低压段转子—轴承系统非线性动力学方程,采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,从而显著提高了数值计算分析的效率.采用Runge-Kutta法对降维后的系统进行多种计算,模拟了200MW汽轮发电机组低压段转子—轴承系统在固定转速下随各个结构参数变化时的动力学行为,主要分析了转子的润滑油黏度、偏心距、轴承长径比、和间隙比对系统前轴承失稳转速的影响.同时利用Flo- quet理论比较准确的分析了系统运动状态和分岔类型.

The nonlinear dynamical model of the low-pressure rotor-bearing of the 200 MW turbine set system is established by FEM, by the fixed-interface component mode synthesis procedure, which is presented. The number of degrees of freedom is reduced sharply from 112 to 8, and the Runge-Kutta method is applied to solve the equation of motion. The numerical results show the rule of the amplitude with the eccentricity of rotor, the length-to-diameter ratio, oil viscosity and the clearance-to-radius ratio of the bearing under the definite speed . Based on the front journal of the generator, the relation of the threshold speed with the variation of the eccentricity of rotor, the length-to-diameter ratio, oil viscosity and the clearance-to-radius ratio of bearing is analyzed, the state of motion and type of the bifurcation are analyzed by Floquet theory.