| Flexible foil aerodynamic bearing technology,as an important part of gas lubrication technology,is a sensitive industrial technology.In aerospace and defense industry and other fields,flexible foil gas bearings as one of the core components,are widely used in fighter aircraft,high temperature gas turbines,cruise missiles,cryogenic cooling systems.Foil gas bearing has good development potential and application prospect in high-speed turbine because of its non-lubricating oil,low maintenance cost and strong environmental adaptability.There are few literatures about the cantilever foil journal bearing,and most researches on multi-leaf foil journal bearings assume that the foils are in line contact.There are many problems with the proposed face contact assumption.For example: the contact between the film and the sleeve is neglected,the tangential friction is neglected in the modeling process,and the initial pre-tightening force is neglected in the assembly of the foil.In view of the above problems,a new physical model of surface contact is constructed and the bearing mechanism is mainly studied,to provide some reference for the optimal design and practical application of foil gas bearings.Cantilever multi-leaf foil radial bearings using multiple foils fixed at one end,the other end in turn overlap in the next foil structure.Firstly,the pre-tightening force is taken into account and the relative geometrical position between the foil and the bearing after assembly is established.By introducing the flexibility coefficient and considering the tangential friction,the relation between stress and deformation of the foil is deduced.Considering the surface contact between the foil and the contact between the foil and the inner wall of the sleeve,according to the contact constraint law,the force-deformation equations of all the foils are combined to obtain the foil flexibility relation matrix.In this paper,the Galerkin method of weighted residual method is used to discretize the gas-lubricated Reynolds equation of gas radial bearings.The elastic deformation of the foil and the pressure of the gas film are iteratively solved.The whole process of gas-elastic coupling is solved.Using MATLAB to program and calculate,the pressure distribution,thickness distribution,stress and deformation of foil can be obtained.The reliability of the calculation model of surface contact was verified.The influence of the rotating speed of rotating shaft and the basic dimensions of foil on the bearing capacity and take-off speed were analyzed to optimize the bearing design.Finally,experiments are conducted to study the cantilever foil journal bearing.According to the characteristics of foil radial bearing,the bearing experiment platform and measuring system are designed.This article designed a convenient foil forming device for processing foil.The experiment of identifying the take-off speed and static characteristics was carried out.The wear and contact condition of the foil was observed.According to the measured data,the influence of the basic parameters on the static characteristics of the bearing was analyzed. |
