The Theoretical And Experimental Study Of Porous Aerostatic Journal Bearing

Aerostatic bearings are widely used in mechanical industry,precision instrument industry,electronic industry and aerospace field as an ideal support component because of its advantages of high precision,resistance to temperature change and radiation,pollution free.Compared with traditional compensation bearings,Porous aerostatic bearing posses higher load capacity,higher stiffness and excellent damping characteristics,therefore,it shows great prospects.The theoretical and experimental research of porous journal aerostatic bearing is carried out in this article.The works have been completed are as follows.Combined with the machining properties of porous bronze material used in the laboratory,the surface pore permeability model is established based on fractal theory.When air gets through the porous restrictor with processing blocking layer,the flow in the porous material follows Darcy' law,while follows orifice compensation law in the processing blocking layer.According to the porous air floating platform manufactured,the theoretical model of porous journal aerostatic bearing with central ventilation is established,and the expression of porous journal bearing' static performance is acquired.The software Fluent based on finite volume method is employed for simulation analysis of the flow field of porous journal bearing,both the distribution of static pressure and velocity magnitude in the porous material and gas film.The six main factors that influence the static performance of porous journal bearing are discussed,including the permeability of porous material,the anisotropy of permeability,supply pressure,bearing aspect ratio,the average thickness of gas film and the thickness of porous material.The variation of permeability is studied during the manufacture of porous journal bearing.The high-precision air floating platform is composed of partial porous thrust bearings and the porous journal bearing,which is employed for the experimental study of porous journal bearing,the result of simulation is verified.This paper provides the theoretical and practice basis of porous journal bearing,besides the flow model through porous restrictor with machining blocking layer is established,which has theoretical significance and practical engineering value.