Research on gas film force of aerostatic gas bearing and its coupled dynamics with rotor

For aerostatic bearings with tangential gas supply,a three dimensional solid model was developed.Combining structured mesh with unstructured mesh,three-dimensional compressible Navier-Stokes (N-S) equations were solved with computational fluid dynamics (CFD) commercial software based on finite volume method.According to the simulation results,gas film supporting force model related to rotor eccentricity and speed was derived with data fitting.Dynamics model of aerostatic bearing-rotor system was built with finite element method and critical speed and unbalance response were solved using Newmark integration method.Experimental tests were performed to verify the numerical simulation results.Research results show that film main supporting force changes linearly in the state of low-speed,small eccentricity,whereas increases rapidly under high-speed and large eccentricity,and effect of dynamic pressure of aerostatic bearing significantly enhances.Coupling supporting force between x and y directions changes nonlinearly with speed and eccentricity;First and second critical speed are sensitive to the current structural stiffness while the third one is not.Therefore,nonlinear characteristics of gas bearing and coupled dynamics of rotor-bearing system are complex;in the case of bearing structure design,coupling between gas bearing and rotor,work speed range should be taken in to full account.