Abstract: The two-degree dynamic model was employed to reveal the vibration coupling mechanism between the rotor system and the stator system according to the rotor dynamics and whole engine dynamics investigation requirements. It is pointed that the calculation error of the traditional rotor dynamical modeling might reach 67% for the worst，so the whole engine modeling is necessary to be used to solve the dynamic characteristics of the aero engines. Further the reductionism principle and the function of the engine model were discussed，and the detailed modeling methods for the typical parts of the rotor and stator were given. The natural vibration characteristics were obtained and evaluated in a certain turbo fan engine with two spools by three dimensional engine model. The results exhibit that there exists only one high pressure rotor’s translational mode between the idling speed and maximum speed ，the strain energy for the rotor system occupied no more than 20%，and the resonance margin was larger than 20%，which satisfied the rotor dynamic design requirement in the aero engines.

Key words: Rotor dynamics；Vibration of the whole engine；Finite element method；Critical speed

摘要： 针对航空发动机的转子/整机动力学问题，使用两自由度动力学模型对转、静子的振动耦合机理进行了解释，指出传统转子动力学模型将导致最大67%的计算误差，因此需要采用整机动力学模型对发动机的振动特性进行求解。进一步明确了整机动力学有限元模型的简化原则和模型功用，针对转、静子的典型结构论述了详细的建模方法。采用整机三维模型对双转子涡扇发动机的固有振动特性进行了计算和评估，结果表明，慢车至最大转速区间内只存在一阶高压转子平动振型，转子系统总应变能不超过20%，共振裕度大于20%，满足航空发动机的转子动力学设计要求。

关键词: 转子动力学；整机振动；有限元；临界转速