Abstract: Aero-engine dual-rotor system is subject to unpredictable excitation, resulting in the random vibration. In order to study this phenomenon, the motion equation of the unbalanced dual-rotor system subjected to random excitation is established. Using pseudo-excitation method, the power spectral density (PSD) of displacement of the dual-rotor system subjected to random excitation is calculated, and the dynamic characteristics of the structure are studied. The researches show that with the increasing of the stiffness coefficient of the intershaft bearing, the natural frequency of the system increases and tend to a constant value. At the same time, the peak of the PSD of displacement caused by external random force decreases and tends to an infinitesimal, while the peak of the PSD of displacement caused by the system coupling effect increases to a peak, then decreases and tends to an infinitesimal after a certain stiffness. From the research, some measures are made for protecting dual-rotor aircraft engines from random vibration. 

Key words: Dual-rotor system; Random excitation; Pseudo-excitation method; Response

摘要： 针对航空发动机双转子系统受到一些无法预测的激励产生随机振动的现象,建立了不平衡双转子系统在随机激励作用下的运动方程。运用虚拟激励法,计算双转子系统在随机力下的位移响应功率谱密度,对其结构动力特性进行了研究。研究表明,当中介轴承刚度系数增大时,系统的固有频率增大并趋于定值。此时,外随机力引起的位移响应谱密度峰值减小并趋于无穷小值,而系统耦合作用引起的位移响应谱密度峰值先上升后减小,并在某个刚度值后,趋于无穷小值。根据研究结果提出了一些预防航空发动机双转子随机振动危害的措施。 

关键词: 双转子系统;随机激励;虚拟激励法;响应