油膜失稳涡动极限环特性的Hopf分叉分析法

由于当转子转速超过失稳门槛后，涡动轨迹逐渐加大，轴承中的油膜力呈现强烈的非线性特性，这时仍用特征值法来预测此系统的动力特性是不行的；如用时域积分法求其涡动轨迹又不能透彻地研究涡动的机理及特性。利用Ｈｏｐｆ分叉分析法，研究了涡动的非线性现象，得到了刚性转子有限长轴承系统的极限环及其稳定性的判据条件，并把其推广到了研究转子在大涡动条件下系统周期介的特性。这为研究非线性涡动的特性开辟了道路，同样这种分析方法亦适合于柔性转子系统的极限环特性分析

Limit cycle characteristics analysis of oil film instability whirl with Hopf bifurcation method

As the speed of the rotor passes through the threshold of instability, the whirl orbit will increase. At this time the oil film force within the bearing becomes strongly non linearized. Using the eigen value method to predict its dynamic properties is unreasonable. By means of time domain step integral method to find out its whirl orbit, the whirl mechanism and its characteristics can not be studied throughly. In this paper, by means of the Hopf bifurcation method, the non linear phenomena of the unstable whirl is researched, the limit cycle and its stable criteria of stiffness rotor supported on fluid film bearings with limited length have been obtained. The above results also have been extended to find out the properties of periodic solution under journal with large whirl orbit. All of the above mentioned methods have opened a new way to study the non linear whirl of the rotor. This analysis method is also suitable for the limit cycle analysis of flexible rotor dynamic system.