箔片轴承转子系统的非线性动力学特性研究

Research on Nonlinear Dynamic Characteristics of the Gas Foil Bearing-Rotor System

气体箔片轴承是一种性能良好的气体动压轴承,但是由于箔片轴承结构较复杂,其动静态特性的求解也更加复杂,计算比较耗时。针对目前常用的弱耦合解法存在计算效率低、耗时长的问题,基于同步求解原理,开发一种计算效率较高的强耦合解法。使用有限差分法计算雷诺方程得到气膜压力分布,将波箔片简化为弹簧模型,然后建立考虑气膜压力、转子运动和箔片变形的箔片轴承转子系统状态方程,实现同步求解。使用该模型对轴承转子系统的动力学特性进行探究,改变转速、转子质量和名义间隙等参数,绘制了转子轨迹图,分析其频谱。仿真结果表明:随着转子转速和质量的增加,系统的稳定性下降;名义间隙过小时,系统变得不稳定,当其增大到某一值时,再增加名义间隙对系统稳定性影响不大。相比传统的弱耦合求解方法,强耦合解法能够进一步提升计算速度和提高计算精度,为箔片轴承的设计和性能预测提供了研究工具。

Gas foil bearings are a kind of aerodynamic bearings with good performance.However,due to its complex structure,the dynamic and static characteristics of the foil bearing are not easy to predict,and the calculation is also time-consuming.Since the widely used weak coupling method is computationally inefficient and time-consuming,a strong coupling method with high computational efficiency was developed based on the simultaneous principle.The pressure distribution was obtained by solving the Reynolds equation using the finite difference method.The bump foil was simplified as a spring model,the state equation of the foil bearing-rotor system was established with consideration of the film pressure,and the motion of the rotor and the deflection of the foil structure,and the simultaneous solution was carried out.Using this model,the dynamic characteristics of the foil bearing-rotor system was investigated by means of the rotor trajectory map and spectrum plot,concerning different parameters including the rotational speed,the rotor mass and the nominal clearance.The simulation results show that the stability of the system becomes worse with the increase of the rotational speed and the rotor mass.The system becomes unstable when the nominal clearance is too small.When the nominal clearance is large enough,the increase of the nominal clearance has little effect on the stability of the system.Compared with the traditional weak coupling method,the strong coupling method can further improve the calculation speed and accuracy,which provides a research tool for foil bearing design and performance prediction.