Design Of A Large Load Spherical Aerostatic Bearing And Research On The Static Characteristic Of The Flow Filed By Numerical Simulation

Spherical aerostatic bearings have low friction, high precision,pollution-free, long life and other advantages of the general aerostatic bearing,and can provide support or degrees of freedom in three directions. So it iswidely used in air bearing platform, precision spindle, gas bearing gyroscopeand other special applications. A large load spherical aerostatic bearing used in alarge attitude adjustment platform are designed and the static characteristic ofits flow field are studied on numerical simulation in this subject.Different types of restrictors are compared firstly, and then a suitable gasbearing structure is chosen. The appropriate values of structural parameters areselected initially by means of engineering design theory of spherical gas bearing.Then the throttling pressure ratio, pressure distribution, load carrying capacity,static rigidity and mass flow rate are calculated under different gas filmthickness by MATLAB.Geometric model of the large load spherical bearing’s gas-film isestablished. Then using GAMBIT carves up gas-film’s mesh and set appropriateboundary conditions. The flow field in gas film was studied by numericalsimulation using computational fluid dynamics (CFD) software FLUENT andthe correctness of the geometric model was proved by comparing withengineering calculations. Through the analysis and comparison on thesimulation result, the rule of gas bearing’s static characteristics (load carryingcapacity, mass flow rate and static rigidity) depending on different parametersincluding ball radius, orifice diameter, orifice number, external angle of socket,internal angle of socket, distribution angle of orifice, air chamber diameter, airchamber depth, supplying pressure is discovered. The optimal parameterscombination and the best static working gas-film thickness of the spherical gasbearing are obtained at last.Static characteristic of the designed large load spherical aerostaticbearing’s flow field was studied by numerical simulation, then getting the staticdistribution characteristics of pressure, velocity and density in the spherical gasfilm under different gas-film thickness (floating height e=11um,16um,21um,26um).Under the optimized parameters combination, the spherical gas bearingsatisfies the design requirement of load carrying capacity and static stiffness andhas a biggish margin. It can provide reference to design such large loadspherical aerostatic bearings.