Research On Dynamic Characteristics And Active Control Of Fixed-tilting Pads Gas Bearing

Due to the characteristics of the low friction,non-pollution,long service life and wide temperature range,the gas bearings have broad application in transportation equipment,aviation and marine equipment,medical equipment.In this paper,the fixed-tilting pads gas bearing-rotor system is taken as the research object.The static and dynamic characteristics of the bearing,and the dynamic behavior of the bearing-rotor system and the active lubrication control are studied,the studies can provide theoretical basis and technical support for the dynamic design,safe and stable operation for the gas bearing-rotor system with fixed-tilting pads.The main research contents are listed as follows:1.For the fixed-tilting pads gas bearing,a hydrodynamic lubrication model is established based on the Reynolds equation.The bearing capacity and minimum film thickness of the gas bearing are obtained by calculating the lubrication model with finite difference method.On this basis,the variations laws of bearing capacity and minimum film thickness with structural parameters is studied.2.Based on the dynamic Reynolds equation of the fixed-tilting pads gas bearing,the partial derivative method is used to calculate the bearing dynamic characteristic coefficient of the journal disturbance,and the journal and bearing co-frequency disturbance.The influence of the structural parameters such as eccentricity,width-to-diameter ratio,disturbance frequency and preload coefficient on the dynamic characteristics of the gas bearings is researched.3.The nonlinear dynamic model of the rotor system supported by the fixed-tilting pads gas bearing is constructed.Based on the dynamic model of the bearing-rotor system,the dynamic behavior of the system is studied by using the trajectory of the journal center,Poincare map and time history are referred to analyze the dynamic behavior.4.Based on the driving principle of piezoelectric actuator,the control model of piezoelectric actuator is constructed,the active the control strategy and control method of active lubrication of the fixed-tilting pads gas bearing are given,and the active control of dynamic response of the bearing-rotor system is realized.On this basis,the influence law of active lubrication control on the operational stability of the system is studied.In summary,this paper provides a reference and technical support for the tribological design and dynamic design of the fixed-tilting pads gas bearings-rotor system.