Numerical Analysis Of Load Capacity Of Aerostatic Radial Air Bearing With Orifice Restrictors

Air bearing is a new kind of bearing which uses air as the lubricating medium.It can be applied to high-speed machine and has the advantages of high rotation accuracy,low wear,low power consumption and long lifetime.With the mechanical rotor system towards higher speed and more efficient,air bearing which can work efficiently in high-speed conditions has been widely paid attention to.However,the current air bearing capacity is smal,and it exists the problem of reliability,leading to the smal-scale application.In this paper,the main factors that affect the bearing capacity of air bearing are analyzed by numerical simulation method,based on the aerostatic radial bearing with orifice restrictors.The main work of this paper is as follows:Firstly,based on certain engineering assumptions,the three-dimensional bearing model is simplified and the two-dimensional bearing model is obtained.Combined with the control equations of gas lubrication,the Reynolds equation of isothermal steady state is deduced.The two-dimensional gas film pressure field is gotten by using the finite difference,with the help of Matlab programming.Then the bearing capacity of air bearing is obtained by integral.In order to verify the finite difference method,the finite volume method is used to solve the air bearing.The geometric model is created by UG and the structured mesh is divided by ICEM CFD.The three-dimensional pressure field of air bearing is obtained by numerical calculation using Fluent.It verifies the correctness of the finite difference method.The finite difference method is used to analyze the factors that may affect the load capacity of aerostatic bearing,including eccentricity,bearing clearance,the pore diameter,the ambient temperature,the number of orifices,and supply pressure.The result shows different parameter has different effect on load capacity of air bearing.Among them,eccentricity,bearing clearance and supply pressure has greater impact.Bigger eccentricity,greater supply pressure and smal er bearing clearance will lead to greater bearing capacity of air bearing.Due to the engineering limitations,it exists the preferred value for the number of orifices and the pore diameter.The best orifice diameter is 0.2mm and the best number of orifices is 8.The work of this paper can provide some reference for the optimal design and selection of aerostatic radial air bearing with orifice restrictors.