超高速箔片气体轴承非线性耦合承载机理及转子动力学研究

This project proposes a ultra-high speed gas foil bearing with 540×104DN. The generalized lubrication equation with boundary slip effect, combined with the foil structure deformation equation and flow equation considering the shaft end sealing foil effect, will be written into a aeroelastic coupled equation of aerodynamic foil gas bearing. The influence of the boundary slip phenomenon, foil deformation and shaft end sealing effect on the nonlinear aeroelastic coupling characteristics of foil bearing will be studied. By using partial derivative method, combine with the dynamic pressure perturbation of third order, the dynamic governing equation(including dynamic stiffness / damping coefficients, second order and third order dynamic coefficients) of gas foil bearing covering the dynamic foil deformation effect will be established. The relation between the nonlinear gas film force and the third order dynamic characteristics of the gas foil bearing will be clarified. And the static and dynamic performance limit solution of the gas foil bearing will be solved. The gas foil bearing rotor system model including elastic shaft section unit and bearing unit will be built, and the nonlinear dynamic stability mechanism of bearing rotor system under ultra-high speed condition will be studied, and the maximum working speed threshold of bearing rotor system will be also given. The research results will provide basic theory, method and application technology support for ultra high speed oil free rotor system.

项目以540×104DN值的超高速箔片气体轴承为研究对象，拟采用计及边界滑移效应的广义润滑控制方程，结合箔片的结构变形方程，考虑箔片轴端封严效应的流量方程，建立箔片气体轴承的气弹耦合方程，揭示箔片气体轴承的边界滑移、箔片变形和轴端封严效应对其非线性气弹耦合性能影响规律；拟运用偏导数法，取动态压力扰动的三阶项，建立涵盖箔片动变形效应的轴承动态特性（包括动态刚度/阻尼、二阶动态系数和三阶动态系数）的耦合控制方程，阐明箔片气体轴承非线性气膜力与其三阶动特性系数的关系，并给出箔片气体轴承静动态性能极限解；拟构建涵盖弹性轴段单元和轴承单元的箔片气体轴承-转子系统模型，研究超高速工况下箔片轴承-转子系统的非线性动力稳定性机理，并给出轴承-转子系统可能达到的最大工作转速的阈值。研究结果将为超高速无油支承转子系统提供基础理论、方法和应用技术支持。

具有极强自适应性的箔片气体轴承的是一种典型的高速轴承，在中、小型空气分离、空气循环系统、环境控制系统及其他高速、无污染场合有着广泛的应用。采用无油润滑的箔片气体轴承由于节省了油润滑系统，减少了对环境的污染，简化了系统结构可采用更加紧凑的轴系结构，减轻了机械损耗，降低了系统维护成本。项目以超高速箔片气体轴承为研究对象，采用了计及边界滑移效应的广义润滑控制方程，结合箔片的结构变形方程，考虑箔片轴端封严效应的流量方程，建立箔片气体轴承的气弹耦合方程，揭示了箔片气体轴承的边界滑移、箔片变形和轴端封严效应对其非线性气 弹耦合性能影响规律；运用偏导数法，取动态压力扰动的三阶项，建立涵盖箔片动变形效应的轴承动态特性（包括动态刚度/阻尼、二阶动态系数和三阶动态系数）的耦合控制方程，阐明了箔片气体轴承非线性气膜力与其三阶动特性系数的关系，并给出箔片气体轴承静动态性能极限解；构建了涵盖弹性轴段单元和轴承单元的箔片气体轴承-转子系统模型，研究超高速工况 下箔片轴承-转子系统的非线性动力稳定性机理，并给出轴承-转子系统可能达到的最大工作转速的阈值。项目研究结果为超高速无油支承转子系统提供基础理论、方法和应用技术支持。