| Air bearings have the advantages of high rotation accuracy,compact structure,near zero friction,no heating,effective isolation of vibration transmission and wide working range,etc.,which can be widely used in high-end equipment manufacturing fields such as high speed and high precision,but air bearings also have the disadvantages of low bearing capacity and poor stability.Therefore,analyzing the influence of different structural parameters and changes in operating conditions on the load capacity,stiffness,and stability of gas bearings has practical guiding significance.Based on gas lubrication theory and aerodynamics,this paper analyzes the influence of different supply pressures,eccentricities,and speeds on the bearing characteristics and stiffness of Aerostatic radial bearings under bidirectional fluid-solid coupling and fluidsolid-thermal coupling conditions.An experimental test rig for gas radial bearings was built for experimental verification.The main research content is as follows:Firstly,based on the theory of gas lubrication and aerodynamics,the paper deduces the theory of air film lubrication for air radial bearings.The geometric structure of air bearing gas film is determined,and the hydrodynamics equation of high pressure gas in air film is obtained.The Reynolds equation of gas lubrication is derived by using the weighted margin method or the finite element method,and the Reynolds equation suitable for the gas film flow characteristics of the gas radial bearing is defined.Gas film boundary conditions coupled between fluid domain solid domain and temperature field.Secondly,based on the theory of gas film lubrication,finite element method is used to analyze the characteristics of gas film flow field.According to the high-pressure gas Flow characteristics in the gas film,the Fluid Flow module and Static Structural module in ANSYS Workbench were used to analyze the gas film flow field,and the standard k-ε model was selected as the FLUENT numerical calculation model.The structure model of the flow field is established and the mesh is divided.The influences of gas supply pressure,eccentricity and spindle speed on air bearing gas film flow characteristics were analyzed,as well as the influences on turbulent kinetic energy and turbulent viscosity of high pressure gas in air film under the conditions of fluid-solid coupling and fluid-solid-thermal coupling,as well as the influences of spindle shape variables.Finally,in this paper,according to the test platform test technical indicators,design the test platform structure size parameters,choose the appropriate standard parts,design,processing of the various parts required by the test platform.Through the method of combining experimental test and numerical simulation,under the same conditions,the air bearing is tested by changing the air supply pressure,eccentricity and spindle speed respectively,and the bearing capacity and stiffness under different working conditions are obtained by recording the data respectively.The bearing capacity and stiffness of air bearing under the same working parameters were compared and analyzed under the fluid-solid coupling and fluid-solid-thermal coupling conditions.The data verification analysis is more consistent with the numerical simulation analysis conditions of the actual working situation. |
