Study On The Texture Lubrication Characteristics And Active Control Of Gas Bearing

Gas bearing are widely used in high-speed precision machinery,medical equipment and electronic industries due to its good performance advantages.In this dissertation,two aspects of research on gas bearing are mainly carried out:based on the fixed-tilting pads combined gas bearing,the lubrication properties of the combined bearing for various dimples texture parameters are analyzed.On the other hand,the dynamic response of active radially lubricated gas bearing based on piezoelectric actuator is studied.The contents are as follows:1.Based on the dynamic pressure lubrication model of fixed-tilting pads combined gas bearing with sphere dimples,the gas-lubrication Reynolds equation is solved by the finite difference method,and the nonlinear gas films and load carrying capacity and friction of combined gas bearing are obtained by coordinate conversion and assembly method.The effects of sphere dimples texture distribution location and geometric parameters on the lubrication performance of combined bearing are analyzed under different texture conditions.2.Taking the maximum load capacity and minimum friction force of the combined gas bearing as the optimization objective functions,based on the desirable ranges of the optimization variables such as texture depth,cell area ratio,and circumferential texture rate,genetic algorithm was used to optimize calculations,and then the texture parameters that achieved the optimization goals are obtained.At the same time,the lubricating performance of the combined gas bearing under local texture and full texture are compared.3.Based on the symmetry Jeffcott rotor model with cylindrical gas bearing support,the dynamic equation of the bearing-rotor system is solved by the direct integral method,and the nonlinear gas film forces are calculated by the finite difference method,the dynamic responses under different rotational speeds are investigated by the orbit diagram,Poincare map,time series diagram.The appropriate piezoelectric actuator is selected for comparison,and the linear relationship between input voltage and output displacement is obtained based on the linear model constructed.4.Based on the piezoelectric actuator and PD controller,an active radial lubrication gas bearing model is established,and the Reynolds equation of active gas-lubrication is derived.Then the gas film pressure distribution of the bearing under active lubrication is solved by the finite difference method,and the dynamic response of the active control system is analyzed based on the Runge-Kutta method.The dynamic response with PD control is analyzed and compared with the dynamic characteristics without active control.The above researches provide theoretical references for the surface texture design of the fixed-tilting pads combined gas bearing and the improvement of the stability of the gas bearing-rotor system.