轴承共腔-双转子系统耦合振动特性研究

Coupling Vibration Characteristics for Shared Bearing Bore-Coaxial Rotor System

为解决某型涡轴发动机振动超标的问题,针对带有轴承共腔结构的先进民用涡轴发动机转子系统,建立轴承共腔-双转子系统非线性动力学模型,考虑滚动轴承和挤压油膜阻尼器的非线性力,实现了耦合振动的交叉频率成分仿真,揭示了轴承共腔-双转子系统耦合振动的机理,并通过了模拟转子试验验证。研究了轴承共腔-双转子系统耦合振动特性及影响因素,结果表明:轴承共腔-双转子的耦合振动表现为交叉激振现象和轴心轨迹的"圆套圆";共腔结构的角向刚度对耦合振动影响较大,而径向刚度则几乎没有影响。此外,4号以及6号支承挤压油膜阻尼器的油膜厚度同样对耦合振动没有影响。通过缩短共腔结构内外安装边的轴向距离,提高了角向刚度,减弱了系统的耦合振动。模拟试验及整机试验结果表明:轴承共腔结构设计合理,转子振动特性稳定。

To reduce excessive vibration of a certain turboshaft engine,dynamic model of the shared bearing bore-coaxial rotor system of the advanced civil turboshaft engine was established with nonlinear forces of the rolling bearings and squeeze film dampers considered.Cross coupling frequency was found incross coupling vibration simulation.Both numerical and experimental studies were conducted to reveal the mechanism of the coupling vibration for the shared bearing bore-coaxial rotor system. The coupling vibration characteristics and influencing factors of the shared bearing bore-coaxial rotor system were studied. The results show that the coupling vibration is featured by cross-excitation phenomenon and orbit which shows a“circle in circle”pattern. Besides,the angular stiffness of the shared bearing bore has great influences on the coupling vibration. However,the radial stiffness and the radial clearance of the squeeze film dampers for No.4 and No.6 supports have almost no effect on the coupling vibration.By shortening the axial distance between the inner and outer mounting edges of the shared bearing bore,the angular stiffness is strengthened and thus reducing the coupling vibration. The aero engine experimental results show that the design of the shared bearing bore is reasonable and effective in maintaining stable operation of the engine.