Numerical Simulation And Analysis Of A Rigid Rotor Supported By Aerodynamic Journal Bearing System

With the development of high-speed, high-efficiency, high-reliability in rotating machinery, the research on bearing-rotor system attract more and more attentions. The researches on the gas bearing static and dynamic characteristics and the dynamics of the gas bearing-rotor system have important theoretical significance in the design of rotating machinery with gas bearing supporting. In this paper, the static and dynamic characteristics of self-acting gas bearing and dynamic behavior of the gas bearing-rotor system are studied. The main contents of this thesis are as follows:(1) From the general form of the journal bearing hydrodynamic lubrication Reynolds equations and gas state equation, the basic form of the steady-state gas-lubricated Reynolds equation is analysized. Using the finite difference method, the static characteristics of the self-acting gas bearing, such as gas film distribution, load capacity and eccentric angle are calculated.(2) The influence of differential step in mesh node on gas film distribution calculation is studied. And the impacts of the rotating speed, eccentric ratio and width-to-diameter ratio on the static bearing characteristics are analysized.(3) The time-dependent gas lubrication transient Reynolds equation is presented. The finite difference method is used to obtain the finite difference form of gas lubrication Reynolds equation. And nonlinear gas film pressure is solved by the Successive Over Relaxation (S.O.R) method.(4) The dynamic model of the self-acting gas bearing-rotor system is established. The rotor dynamics equations is calculated coupled with gas lubrication transient Reynolds equation. Trajectories spectrum, time domain spectrum and frequency spectrum are used to study the nonlinear dynamic characteristics of Jeffcott rotor model supported by the self-acting gas bearing.