Study On The Working Characteristics Of Aerostatic Thrust Bearings With Ultra-high Floating

In the large-scale ground physics simulation experiment of the space vehicle,the whole high-precision large-plane air flotation platform is difficult to process,and the small piece of air flotation platform is often spliced in practical engineering applications,which makes the aerostatic thrust bearings face the process of crossing the gap between blocks during the working process.However,the height difference between the splicing blocks,caulking bulges,air leakage and other problems will cause the original boundary conditions of the bearings air film to change,which will further lead to the deterioration of the bearings characteristics and stiffness characteristics of the aerostatic thrust bearings,and even cause the contact friction between the bearings and the air flotation platform in serious cases,so the floating amount of the bearings need to be limited.In the research of bearings floating,experts and scholars at home and abroad have done a lot of in-depth and detailed research on the static/dynamic characteristics of bearings under low float(≤10μm),medium float(10～20μm)and high float(20～30μm).However,the floating capacity is still not enough to meet the needs of cross-seam,so the development of ultra-high floating aerostatic thrust bearings and ensuring their stable and reliable operation have become an urgent problem to be solved in the current ground micro-low gravity simulation experiment.Therefore,this project takes ultra-high floating aerostatic thrust bearings as the research object,and analyzes the static/dynamic characteristics of bearings and their gas membrane flow field characteristics under different air supply hole numbers,different equalizing groove structures and different eccentric loads,so as to clarify their working characteristics under different working conditions.The research content of this paper is as follows:Firstly,starting from the working principle of aerostatic thrust bearings,the mathematical model of the bearing air film flow field are established,and then the characteristics of the air film flow field are analyzed theoretically.Then,by the method of numerical calculation under different working conditions,the high amount of float aerostatic thrust bearing of the static/dynamic characteristics are studied.In terms of static characteristics,the bearings characteristics and stiffness characteristics of aerostatic thrust bearings under ultra-high floating capacity are mainly studied,and the influencing factors include different air supply pressure,different floating volume,different number of air supply holes,different equalization groove structure,etc.Through the comparison of the static characteristics of bearings under different structural parameters and working parameters,the static characteristics change law of bearings under ultra-high floating capacity and the calculation method of their air film flow field are clarified.In terms of dynamic characteristics,the vibration intensity and vibration frequency of aerostatic thrust bearings under ultra-high float capacity are analyzed,and the influence of different structural parameters and different eccentric load conditions on the micro-vibration characteristics of aerostatic thrust bearings under ultra-high float are discussed.Finally,experimental verification of static and dynamic characteristics of aerostatic thrust bearings under ultra-high buoyancy are completed.The results show that there are supersonic and negative pressure regions inside the bearings air film under ultra-high floating,and the large pressure drop of the air film and the enhancement of the compressibility of the fluid will lead to the deterioration of the static characteristics of the air bearings;Appropriately increase the air supply pressure,increase the number of air supply holes and the working characteristics of the bearings under the superfloating starting capacity that can be effectively improved by the structure of the equalizing groove;Considering the fluid-solid-thermal coupling effect under ultra-high floating,it can effectively improve the calculation accuracy of the working characteristics of aerostatic thrust bearings.When supplying 50μm gas film with 1MPa,the calculation error of bearing capacity is only 2.2%,and the calculation error of stiffness is only 2.7%.