Analysis Of Static And Dynamic Characteristics Of The Micro Gas Bearing-nonlinear Rotor System

As a key supporting component of the new generation power MEMS such as micro-turbine engines and micro motors,the micro high-speed gas bearing has static and dynamic characteristics that are particularly important for the non-linear dynamics design of the complete machine.This dissertation aims to study the static and dynamic characteristics and dynamic behaviors of the micro high-speed gas bearing-rotor system.The main contents are as follows:1.For the micro high-speed fixed-tilting-pad gas combination bearing,the Reynolds equation considering the first-order slip model and the rarefaction effect is obtained The modified Reynolds equation of the micro gas bearing is solved based on the Galerkin weighted residual method,and the nonlinear gas film pressure distribution is obtained,the influence of the rarefaction effect on gas film pressure is analyzed.The static characteristics of micro fixed-tilting-pad gas combination bearing with different Knudsen number,bearing number,and eccentricity are studied.2.Based on the dynamic Reynolds equation of micro gas bearing,the dynamic eccentricity and attitude angle are expressed as the plural form with periodic disturbance.The dynamic gas film pressure and film thickness are solved in the complex plane.The partial derivative method is used to calculate the dynamic stiffness and damping coefficient of the gas bearing.The influence of the parameters such as rarefaction effect,eccentricity and journal disturbance frequency on the dynamic performance of the gas bearing with three axial grooves is studied.3.Aiming at the rotor system supported by gas bearings with three axial groves in MEMS,the nonlinear dynamic model is established.The dynamic equations of the micro bearing-rotor system are solved,by the journal trajectory map,Poincare map and time series to analyze the dynamic behavior of the system.The influence of gas rarefaction on dynamic response of rotor system supported by micro gas bearing with three axial grooves is studied.4.Considering the influence of temperature and pressure on gas film viscosity,density and gas flow velocity,the thermal hydrodynamic lubrication model of the micro gas bearing with three axial grooves is constructed based on the temperature equation,gas film energy equation,heat flow continuity equation and modified Reynolds equation.Based on the proposed model,the influence of rotating speed.and eccentric ratio on the temperature distribution and static performance of the the micro gas bearing with three axial grooves is analyzed.This dissertation can provide a reference for the tribological and dynamic design of the new generation MEMS supported by gas bearing-rotor system.