Dynamics of Rotors on Hydrodynamic Bearings

R. Eling[1]
[1]Mitsubishi Turbocharger & Engine Europe, Almere, The Netherlands

This study presents a rotordynamic analysis of a rotor on hydrodynamic bearings using COMSOL Multiphysics®. In this paper, the complexity of the model is gradually increased. Starting point of the analysis is the modal analysis of the rotor in free-free conditions. A Reynolds model is set up to predict the film pressure distribution under shaft loading. Due to the cross coupling terms of the bearing stiffness coefficients, instability can occur. A point mass simulation of the shaft in a hydrodynamic bearing is able to predict the whirl frequency and amplitude of the bearing itself. Coupling the hydrodynamic bearings to a flexible shaft, the whirl can be seen to interact with the rotor natural frequencies.