高维反向旋转双转子系统的建模方法及动力特性

为了弥补有限元方法预测含局部非线性的双转子系统动力特性的不足,借助有限元软件和固定界面模态综合法,建立了高维双转子系统非线性动力学模型,随后利用Newmark算法思想提出了一种隐式时域求解该问题的方法,该方法的求解效率主要取决于非线性力处的自由度个数.在考虑挤压油膜阻尼器非线性力和中介轴承非线性力的基础上,研究了双不平衡激励作用下的反向旋转双转子系统的非线性动力响应特性.研究表明:系统响应中除内、外转子自转频率外,出现了2个自转频率的组合频率;随中介轴承径向游隙的增加,系统转速分岔图中出现了分岔和混沌现象,且临界转速略有下降;系统轴心轨迹呈花瓣状,与试验结果基本吻合.

Modeling method and dynamic characteristics of high-dimensional counter-rotating dual rotor system

To make up the deficiency of the finite element method in predicting dynamic characteristics of the dual-rotor system with local nonlinear, high-dimensional nonlinear dynamic model of dual-rotor system was established with finite element software and fixed interface modal synthesis method; subsequently an implicit time-domain method was presented to solve the problem using the Newmark algorithm ideas, and the computational efficiency of this method was largely dependent on the number of degrees of freedom at nonlinear forces' location. Considering the nonlinear forces of squeeze film damper and inter-shaft bearing, the nonlinear dynamic response characteristics of the counter-rotating dual rotor system under dual imbalance force were studied. The study shows that there are some combinations of these two rotation frequencies in system response, in addition to rotation frequencies of the internal and external rotors. Besides, bifurcation and chaos emerge in system speed bifurcation diagram and the critical speeds decrease slightly with the increasing inter-shaft bearing radial clearance. The axis orbit of the system will be of a petal shape, which is basically consistent with the experimental results.