Nonlinear behavior analysis of a rotor on two-lobe wave journal bearings

The dynamics of an unbalanced rigid rotor on two-lobe journal bearings with wave profile, symmetrically placed at its ends, is studied in numerical way. The radial dissymmetry of the shape given to the bearing bore makes the angular orientation of the same bearing one of the main parameters in the study of the system dynamics. Further parameters adopted in the investigations are the amplitude of the wave component which characterizes the profile of the bearing bore, the static unbalance and the speed of the rotor. Brute-force integration of system equations has been carried out in order to obtain qualitative portraits of the system dynamics in terms of bifurcation diagrams and trajectories of the journal centre. The study also illustrates the way numerical continuation method can highlight the dependence of the stable, synchronous response on the adopted parameters and allow a tracking of the same motion in a simulated run-up of the rotor.