Analysis Of Dynamic Characteristics Of Aerostatic Bearing With Orifice Restrictors And Corresponding Rotor-Bearing System

Aerostatic bearing is one of the major types of gas bearings. Because of the obvious advantage of high rotary speed and precision, pollution free lubrication and so on ,aerostatic bearing becomes widely applied in the areas of precision lathe and measuring instrument, cryogenic compress industry, foodstuff industry, medical treatment ,nuclear industry, aviation and spaceflight industry. However, the aerostatic bearing-rotor system easily generates vibration under excitation, when the rotary speed comes to the intrinsic frequency of the system, the journal and the bearing contacts each other, as affect the safety and reliability of equipments, further more, the horrible accident which bearings are marred and the rotor system becomes broken down.In order to improve the performance of aerostatic bearing and enhance the reliability of system, the chief works of this paper represents as follows:First, on the foundation of development and present research situation of internal and external aerostatic bearings, this paper summarizes the principle of aerostatic bearing, according to several assumptions of work conditions, two-dimensional Reynolds equation of isotherm compressible fluid is deduced. The nonlinear dimensionless Reynolds equation is then derived and subsequently discretized using the Finite Differential Method(FDM), and modified Reynolds equation is solved by means of the iterative Newton Method. For higher calculation efficiency, the successive (over-)relaxation method is adopted to solve the equation. (The iterative algorithm of the equation is given.) The calculating program of nodes pressure array, bearing load capacity, stiffness and gas flow are written in Fortran language and Matlab7.1 software ,and the program charts are given. Then, detailed analysis is made of results. And the results present that the mathematical calculation based on FDM is fast and easy to be achieved , and the precision satisfies the requirement.Second, Finite Element Method (FEM) is used to establish the dynamic model of certain turbine expresser rotor-bearing system, which is supported on two aerostatic bearings with orifice restrictors, stiffness matrix and mass matrix are obtained. Then the unbalance response is solved in Newmark Method, and the...