线性与非线性油膜力模型下转子振动稳定性对比研究

Comparison Study of 200MW Turbine Low-pressure Rotor Supported by Linear and Nonlinear Model

滑动轴承的油膜力直接影响转子振动的稳定性,首次对大型多自由度转子系统在线性和非线性油膜力作用下的振动稳定性进行了对比分析。针对200MW汽轮机低压转子-轴承系统,采用数值计算方法分别模拟了转子在非线性油膜力和传统的8个刚度和阻尼系数表示的线性油膜力模型下,转子升速过程中发生油膜失稳的典型特征。通过比较分析得出考虑油膜力的非线性特性后转子发生油膜振荡的转速提前。因此为保证大型转子-轴承系统的安全稳定运行,有必要在传统线性理论设计的基础上,引入非线性油膜力形式对系统的稳定性作进一步的计算校验。

The oil film force of the sliding bearing has direct influence on the stability of rotor vibration. The stability of vibration of a large scale rotorbearing system supported on nonlinear model of oil film force and linear model expressed by eight rigidity and damping coefficients is compared and analyzed. By the numerical calculation method, the typical characteristics of oil film instability of the low pressure rotorbearing system of 200MW turbine set is simulated separately during the speed up process. By comparing, we concluded that the threshold speed of the oil whip of a rotor supported on nonlinear model of oil film force is lower than that on the linear model. In order to guarantee the system operating safely, it is necessary to apply nonlinear oil film force model to the designing process to verify the stability of the system further.