Study On Lubrication Mechanism Of Foil Gas Bearing Under Multi-field-coupling

Elastic foil gas bearings are self-acting hydrodynamic bearings with gas as lubricating medium and flexible surface supported.They have some characteristics of small mass,lower cost,higher stability,lower power loss,impact resistance,higher and lower temperature resistance,higher bearing capacity and so on.It is widely used in industry,agriculture and aerospace.But at present,compared with the foreign mature experimental and applied researches,the domestic experimental researches on bearings are mainly focused on the static and dynamic characteristics and the stability of the rotor bearing system,and the researches on the foundation performance testing and the design and manufacturing of foil gas bearings are seriously lacked.In view of this,the theoretical study of foil gas bearing is carried out,and the influence of relevant parameters on the film pressure is discussed.In this paper,a numerical model of elastic fluid dynamic lubrication for thrust foil gas dynamic bearing is established.Based on the structural characteristics and working characteristics of the thrust foil gas dynamic bearing,the elastic deformation model with linear damping and stiffness is analyzed.The dimensionless Reynolds equations in the polar coordinates are derived,the finite difference method(FDM)and the SOR iterative method are used for numerical calculation,and the difference equations are solved by MATLAB programming to obtain the pressure distribution and film thickness distribution of the bearing.Two linearization methods are used to calculate the nonlinear pressure governing Reynolds equation.One is the classical Newton-Raphson method.In addition,a linear substitution method is proposed to deal with the dimensionless finite difference equations.Under the same bearing structure parameters,the pressure distribution and the maximum film pressure value are obtained.The results show that the two methods have good convergence and the error is less than 5%,which shows the reliability and credibility of the method.The pressure distributions of the film are obtained by changing the relevant parameters of the bearing.The results show that the gas film pressure distribution is related to the minimum gas film thickness,rotor speed and pitch ratio.The maximum pressure value of the gas film increases with the speed of the rotor,and then affects the bearing capacity and friction torque of the bearing,which has a certain theoretical guiding significance for the design and manufacturing of the bearing.A numerical model of elastic fluid dynamic lubrication is established for the foil gas journal bearings.The dimensionless equation in the cylindrical coordinate system is derived,and the finite difference method and the(SOR)iteration method are used to calculate the gas film pressure and film thickness distribution on the rigid surface.The error of the maximum value of the film pressure obtained by MATLAB programming less than 3% when compared with the literature.It shows that the coupling method for solving the pressure governing Reynolds equation is feasible.