Research On Nonlinear Dynamic Response Of Foil Air Bearings

Bearings are a key component in high-speed machinery.Compared with the traditional oil-lubricated bearings,gas-lubricated bearings are widely used in high-speed machinery,precision instruments and harsh environments due to their low inherent friction and high reliability.Wave foil dynamic pressure gas bearing is a kind of foil gas bearing with good performance,which is widely used in all kinds of high speed machinery.However,because the structure of foil bearing is complex,the dynamic and static characteristics of foil bearing are complex,the calculation is complex and time-consuming,and the efficiency is not high enough.In order to solve the problems of low computational efficiency and long time consuming of weak coupling solutions,a strong coupling solution with high computational efficiency is developed by using simultaneous solutions.The model of bump foil bearing and the Aeroelastic coupling equation of bump foil bearing are established.Compared with the rigid surface bearing,the bump foil bearing needs a foil deformation equation.As for air buoyancy,the integral formula of air pressure is closer to the actual situation than the linear equation,and for the force of the rotor,the cylindrical vortex and the conical vortex are considered respectively,and the dynamic equations are listed.Considering the influence of conical vortex,the corresponding equations are derived,the corresponding algorithm of finite difference method is analyzed,and the trajectory of rotor under conical vortex and the influence of initial angle offset on the system are discussed.the results show that the stable state of the system is independent of the initial disturbance,and the rotor only makes cylindrical vortex when the system is stable.The dynamic characteristics of bearing rotor system are investigated.The parameters such as rotational speed and rotor quality are changed,the rotor trajectory map is simulated,and its spectrum is analyzed.the simulation results show that the stability of the system decreases with the increase of rotor speed and quality;the film gap is too small and the system is unstable.when the film gap is large enough to a certain value,the increase of the film gap again has little effect on the stability of the system.