Study Of Cross-scale Numerical Computation Method Of Aerostatic Bearings

Aerostatic bearings is the core device of ultra-precision motion stages, have beenwidely used in the field of precision metrology technology and subtle processingbecause of their friction-free, high speed and high accuracy of motion etc. Theirresearch progress has driven the relevant industries forward to certain extent. Thefurther analysis of the static load capacity and stiffness is particularly important withthe ultra-precision motion stages requiring higher precision. However the ratio of thegeometry size of aerostatic bearings to gas film is more than1000:1, it leads tomeshing difficulty and the low computational efficiency because of the large quantityof grid. Therefore, this thesis’s goal is to solve that problem of aerostatic bearingswith cross-scale numerical computation method.First of all, the working principle of aerostatic bearings and the model of cross-scale numerical simulation method are introduced by this thesis. and the general formof gas-lubricated Reynolds equation is derived by joint solution of the equationgoverning the motion of fluid and gas state equation.Secondly, the general process of the simulation computation of none pressurechamber and with pressure chamber aerostatic bearings by cross-scale numericalcomputation method. Meanwhile the pressure distribution in the gas film of thebearing is displayed in two-dimension coordinates by the method to none pressurechamber and with pressure chamber aerostatic bearings.Finally, based on the, the pressure distribution and static characteristics ofbearing’s orifice and pressure chamber have been calculated by CFD software fluent.Simultaneous based on the finite difference method, the Reynolds equation governingthe pressure distribution in gas film is solved. The static load capacity and stiffness inthe gas gap of the bearing are thus obtained after the pressure distribution beingobtained, by through MATLAB software solving the discrete Reynolds equation. Andthen the static characteristics of the whole bearing are composed of the static loadcapacity and stiffness of orifice, pressure chamber and gas film. And the result of cross-scale computation has been compared with the result of FLUENT simulation.The cross-scale numerical computation method is feasible according to the researchresult.