高速柔性转子-非定心SFD系统响应特征分析与试验验证

Analysis and test verification for response characteristics of high-speed flexible rotor-non centered SFD system

航空发动机转子系统通常在支承处设置挤压油膜阻尼器(squeeze film damper,SFD)来实现系统减振设计,与定心SFD相比,非定心SFD结构简单紧凑,减振效果良好,但是具有更强的非线性特征,动力特性更为复杂。以某航空发动机动力涡轮转子为研究对象,建立了多支点高速柔性转子-非定心SFD系统非线性动力学模型,考虑了非定心SFD静偏心的影响,采用数值方法求解转子系统响应,结合系统不平衡响应特征、分岔图、庞家莱截面、频谱等,开展了系统非线性动力学特性研究,并通过了转子试验验证。研究结果表明,非定心SFD油膜间隙较大时,转子系统存在较强的非线性运动,频率成分丰富,减小油膜间隙能够使系统在跨临界后为单周期运动,降低系统的非线性不平衡响应;但过小的油膜间隙将导致转子系统峰值响应和对应的转速显著增大,转子可工作转速范围变小,合理的油膜间隙可以兼顾非线性振动响应和峰值转速较小,实现转子系统在大转速范围内长时间运行。

Rotor system of aircraft engines is usually equipped with squeeze film damper(SFD)at supports to realize system vibration reduction design.Compared with centered SFD,non-centered SFD has a simple and compact structure,and good vibration reduction effect,but possesses stronger nonlinear features and more complex dynamic characteristics.Here,a certain power turbine rotor of aircraft engine was taken as the study object,and a nonlinear dynamic model was established for multi-pivot high-speed flexible rotor-non centered SFD system considering effects of static eccentricity of non-centered SFD.Numerical methods were used to solve the rotor system responses,combining system unbalance response characteristics,bifurcation diagram,Poincarécross-section and frequency spectrum,etc.,nonlinear dynamic characteristics of the rotor system were studied,and verified with rotor tests.The study results showed that when non centered SFD’s oil clearance is larger,the rotor system has stronger nonlinear motion and rich frequency components;reducing oil clearance can make the system have a single period motion after trans-critical to reduce nonlinear unbalance response of the system;but,too small oil clearance can cause significant increase in peak response and corresponding rotating speed of the rotor system,and the range of the rotor’s working rotating speed becomes smaller;reasonable oil clearance can make the rotor system have smaller nonlinear vibration response and lower peak value rotating speed,and realize its operating for a long time within a large rotating speed range.