承力系统动态特性对发动机整机振动特性的影响

Influence of Dynamic Characteristics of Support System on Whole Engine Vibration Characteristics

为了解决航空发动机承力系统对转子系统振动特性影响较大的问题,建立了发动机承力系统分析模型,分析其固有模态及动态特性。通过将固有频率计算结果与试验结果进行对比,验证了所建模型的准确性。建立了转子-支承-机匣-安装节系统模型,分析了整机系统高压激振下的临界转速与应变能。结果表明:在固有频率附近承力系统刚度值大小和相位发生显著变化,在一定频段内出现相位持续反向的负刚度。与采用静刚度的1维双转子-支承系统进行对比,在振型方面,双转子-支承系统同阶振型下整机模型更能体现由转子激起的机匣振动的不同情况;在应变能方面,由于负刚度的影响难以用静刚度来描述,采用双转子-支承系统分析方法使某阶振型的支点应变能计算不准确,采用静刚度的1维双转子-支承系统分析发动机振动特性的方法会产生误差。整机分析模型更能考虑机匣动态特性对转子振动的耦合影响,更贴近实际发动机工作情况。研究结果可供航空发动机整机振动设计参考。

In order to solve the problem of the significant impact of the support system of an aeroengine on the vibration characteristics of the rotor subsystem,an analysis model of the support system was established to analyze its natural modes and dynamic characteristics.By comparing the calculated natural frequency with the experimental results,the accuracy of the model was verified.The model of rotor-support-casing-mounting joint system was established,and the critical speeds and strain energy of the whole system under high pressure rotor excitation were analyzed.The results show that there is a significant change in the stiffness value and phase of the sup⁃port system near the natural frequency,and the negative stiffness with continuous phase reversal occurs within a certain frequency band.Compared with the one-dimensional dual-rotor-support system with static stiffness,in terms of vibration mode,the whole engine model of the dual-rotor-support system with the same order of vibration mode can better reflect the different situations of casing vibration induced by the rotor;in terms of strain energy,due to the difficulty in describing the influence of negative stiffness using static stiffness,the use of dual-rotor-support system analysis method results in inaccurate calculation of the support strain energy for a certain order of vibration mode,and the method of analyzing engine vibration characteristics by using one-dimensional dual-rotor-support system with static stiff⁃ness will result in errors.The whole engine analysis model can better consider the coupling effect of the dynamic characteristics of the cas⁃ing on the rotor vibration,which is closer to actual engine operating conditions.The results can be used as a reference for the whole engine vibration design of aeroengines.