轴承标高对多跨转子-轴承系统非线性稳定性的影响研究

建立了考虑转子-轴承标高与非线性油膜力的多跨转子-轴承系统高维非线性动力学模型。利用固定界面模态综合法对该模型进行降维，采用Newmark逐步积分法对降维后的动力学模型进行数值计算，可得到转子在各种标高情况下发生油膜失稳的转速门槛值和轴承标高变化对系统动力稳定性的影响规律。对200MW汽轮发电机组转子-轴承系统计算分析表明：由于低压转子后轴承的标高抬起，将导致发电机转子前轴承轴颈的失稳转速显著提前，系统的稳定性降低。分析结果从理论上解释了电站200MW汽轮发电机组发电机前轴承处转子易发生油膜失稳的原因，并且证明了本文所提出方法的有效性。

The Effect of Bearing Elevation on Nonlinear Stability of Multi-Bearing Rotor System

A dynamic model of a multi-bearing rotor system was established with bearing elevation and nonlinear film force taken into consideration. Based on the dynamic model the instability threshold speeds of the system under various bearing elevation and the effect of bearing elevation on the margin of stability can be computed numerically by Newmark method after reducing its degrees of freedom. As an example, the actual rotor-bearing system of a 200MW turbine generator set is analyzed by increasing the behind bearing elevation of low-pressure rotor. It is shown that the instability threshold speed of ahead bearing journal of generator is decreased remarkably. The results account for the cause of instability of generator rotor in practice, and verify the effectiveness of the proposed method in this study.