Nonlinear Behaviors and Bifurcation of Flexible Rotor System with Axial-Grooved Self-Acting Gas Bearing Support

The unbalanced responses and corresponding bifurcation behaviors of the rotor dynamic system supported by axial-grooved gas journal bearings are investigated. A time-dependent mathematical model is used to describe the pressure distribution of axial-grooved gas journal bearing with nonlinearity. The dynamic model of the flexible rotor system with axial-grooved gas journal bearing supports is established. The finite difference method and the Successive Over Relaxation (S.O.R) method are employed to solve the time-dependent Reynolds equation of axial-grooved gas journal bearing. The unbalanced responses and bifurcation of the rotor dynamic system supported by finite width axial-grooved gas journal bearings are analyzed by orbit diagram, Poincaré map diagram, time series diagram, frequency spectrum diagram and bifurcation diagram. Numerical results reveal that the nonlinear gas film forces have a significant influence on the stability of rotor system and there are the rich and complex nonlinear phenomena, such as periodic, quasi-periodic motion, etc. The proposed model and numerical results can provide a theoretical direction to the design of practical gas-lubricated bearing-rotor system.