Study On Load Characteristics Of Gas Dynamic Bearing With Eight Cantilever Foil Based On Contact Mechanics

The foil dynamic pressure bearing is a kind of bearing with elastic foil forming the flexible contact surface,and it is formed by the dynamic pressure effect non-contact rotation.The advantages are good adaptability under extreme temperature environment,good damping characteristics under high speed conditions,good tolerance of assembly error and long service life.Therefore,it has been put into practical use in low temperature oxygen generators,air cycle machines,micro turbojet engines,micro gas turbines,turbochargers,and high-speed fans.However,there are few technical materials available for cantilever-type foil bearings,and they are mainly controlled by foreign scientific research institutions.At the same time,the overlapping structure of the thin sheets is complicated and the theoretical modeling is not perfect.Therefore,the main work of this paper is to construct a theoretical model that takes into account many factors,simulate and calculate,and then carry out experimental verification of the model through experimental research.In this paper,the bearing-gas film-rotor system is fully theoretically modeled based on the finite element method.Firstly,a finite element model is established for each cantilever using a curved beam element.Secondly,considering the contact constraints between the foils,between the foil and the bushing,between the foil and the rotor,the contact model between the structures is constructed based on the calculated contact mechanics,and the overlapping foils are calculated by the Newton iteration method nonlinear deformation of the structure.At the same time,the rotor assembly and static loading process are also theoretically modeled,so that the theoretical calculation of the foil bearing is closer to the actual physical model.Regarding the gas film analysis,the stepwise reduction of the Reynolds equation based on the Galerkin method is solved by the finite element method,and the thickness and pressure distribution of the gas film are obtained.The aeroelastic coupling calculation is completed,and the theoretical performance of the cantilever type sheet bearing is finally completed overall modeling.After programming the model,the obtained loading simulation results show that the rotor speed has little effect on the ultimate bearing capacity of the bearing.In addition,after considering the bushing constraints,the calculated bearing capacity is larger and closer to the experimental value.The bearing characteristics of the cantilever-type foil bearing are greatly influenced by the thickness of the foil,the radius of curvature of the foil and the radial clearance,and the analytical parameters have theoretically optimal values for improving the ultimate bearing capacity of the bearing.In this paper,a platform for performance test of eight cantilever sheet bearings is designed and built.The bearing experimental parts are designed and processed.The static rotor loading and unloading experiment is completed.The bearing characteristics of the sheet structure are obtained,and the bearing loading test is carried out under different rotor speed conditions.Bearing carrying capacity.The results obtained show that the rotor speed has a small impact on the bearing characteristics of the bearing,and the actual structural stiffness and ultimate load are measured to be larger than the simulation results.