GMA可控油膜轴承-转子系统的稳定性研究

The controllable oil film bearing-rotor system with the giant magnetostrictive drivers (GMA) has merits of long service life and heavy loading The controllable oil film journal bearing-rotor system with the giant magnetostrictive drivers (GMA) not only has merits of long service life and heavy loading capacity as the traditional oil film journal bearing-rotor system, but also has similar characteristics of high position accuracy and perfect control as the magnetic levitation bearing-rotor system. The dynamic and static characteristics of the oil-film journal bearing with GMA and the stability of the rotor system supported by the controllable bearing at high speed are investigated in this project. The main work is as follows: The calculation model of the oil film force considering air-pocket effects and negative pressure effects is presented in the new controllable bearing. Considering surface tension of oil, the continuous stress boundary condition at the interface between the cavitation and full-film regions is adopted to build up the model of oil-film force. According to the model, a new program is developed to calculate the dynamic and static characteristics of the bearing. The interface grid tracking technology is utilized to determine the dynamic boundary location of air pockets in the process of programming. And the kinetic equations of the controllable bearing-rotor system with GMA are presented. Another program is developed to simulate the centerline orbits of the rotor supported by the controllable bearing with GMA under different working conditions. Using this program, the effect of GMA controlling parameters as well as oil film negative pressure and air-pocket on the high-speed stability of the rotor system is analyzed. The stability criterion of the oil film bearing-rotor system with GMA is also constructed. At last, the controllable hydrodynamic oil film bearing test-rig is designed. The testing rotor is directly supported by two controllable bearings with GMA. The effect of GMA controlling parameters on the formation of oil film air-pocket and negative pressure area is investigated under different testing conditions. The theoretical models, numerical simulation results and stability criterion presented in this project are also verified by testing. This study can lay the theoretical foundation for the controllable journal bearing-rotor system with GMA used in high speed and high precision rotating machinery.

基于超磁致伸缩驱动器(GMA)的可控油膜轴承-转子系统既保留了传统油膜轴承-转子系统寿命长、承载力大的优点，又具有类似磁悬浮轴承-转子系统可控、回转精度高的特点。本项目将主要研究GMA可控油膜轴承的动、静特性和所支承转子系统在高速工况时的稳定性。考虑油的表面张力，推导气穴应力连续边界条件，建立存在气穴和负压的油膜力模型，利用界面网格追踪技术确定动态气穴的边界位置，研究受控油膜轴承的动、静特性；建立GMA油膜轴承-转子系统的动力学模型，利用数值方法模拟不同工况下的轴心运动轨迹，研究GMA控制参数、气穴、负压等对受控油膜轴承-转子系统稳定性的影响，构建受控油膜轴承-转子系统的稳定性判据；利用试验手段研究GMA控制参数对油膜气穴和负压形成的影响，验证理论模型、数值模拟和稳定性判据的正确性。本研究将为GMA可控油膜轴承-转子系统在高速、高精度旋转机械中的应用奠定一定的理论基础。

GMA油膜轴承-转子系统具有旋转精度高、寿命长和控制方便的特点，在高速旋转机械中具有良好的应用前景。项目考虑了气穴的影响，从理论和实验两方面研究了GMA可控油膜轴承的动、静特性以及所支撑转子系统的稳定性。.理论方面的工作有：①考虑润滑油的表面张力，推导了气穴应力连续边界条件，建立了含有气穴的油膜力模型，利用静网格方法，考察了负压、进油压力、长径比、偏心率和转速等参数对轴承动、静态性能的影响；②提出了基于CFD软件的动网格更新算法，纳入气穴边界条件，编制了油膜轴承-转子系统的轴心轨迹计算程序，考察了轴承座受位移激励、正弦激励以及GMA控制时各参数对系统不平衡响应的影响；③建立了GMA油膜轴承-转子系统的动力学模型，推导了GMA轴承所支撑的刚性转子系统的稳定性判据，并针对GMA所支撑的存在不平衡的柔性转子系统，采用FORTRAN、VISUAL BASIC和MATLAB三种语言混合编程的方法，分析了GMA控制参数、转子刚度、轴承和转子质量等参数对系统失稳转速的影响。实验方面的工作有：①设计了三自由度的GMA油膜轴承可视化试验台，加工了4套有机玻璃滑动轴承；②搭建了试验台的测控系统，进行了GMA在不同载荷和电流下的静态和动态性能实验以及轴承底板的控制测试；③针对每一套轴承，进行了16种不同转速、不同进油压力和不同偏心率下GMA滑动轴承的压力分布和温度分布实验，控制轴心轨迹实验，观察并记录了偏心率、转速和进油压力对油膜的形成与破裂的影响。.理论和实验结果表明，气穴对轻载下的滑动轴承的承载性能影响较大，合适的GMA控制参数能抑制油膜轴承所支撑转子系统的不平衡响应，提高系统的失稳转速，并存在一个最佳相位差能够使系统的失稳转速最高，并且失稳转速随转子刚度的增大而增大；在动态气穴内，存在润滑油丝和润滑油滴，它们逆着旋转油流的方向移动，并随着转速升高，气穴面积增加，气穴的初始位置提前。.综上所述，在理论分析、数值计算和实验等方面完成了项目任务书的要求，并在轴承气穴模型中考虑油的表面张力推导了气穴应力边界条件，在转子轴心轨迹计算中提出新的动网格更新算法，并通过实验验证。推导的动态气穴模型、提出的动网格算法和建立的GMA轴承转子系统的稳定性分析方法能为滑动轴承的理论建模与数值计算方法提供借鉴意义，不仅可以丰富润滑理论的内容，而且可以对滑动轴承的工业应用提供重要的参考资料。