Dynamic Response of a Hydrodynamic Thrust Bearing-Mounted Rotor

For investigating the dynamic response of a hydrodynamic thrust bearing-mounted flexible rotor, the dynamic characteristic data of thrust bearings for high surface velocities are applied for constructing the equation of motion for the rotor system, which is modeled with the finite element method. Based on the short bearing approximation and the π film cavitation model of the nonlinear oil-film forces, the dynamic responses are investigated using direct numerical integration with a variable order solver based on the numerical differentiation formulas. Harmonic, quasi-periodic, and chaotic motions are predicted for a range of spin speeds of the rotor. Poincare´ maps of predicted rotor trajectories are also examined. It shows that spin speeds of the rotor and the oil film force coefficient might promote undesirable nonsynchronous vibrations.