The improvement of rotordynamic systems being supported by oil-lubricated journal bearings represents an ongoing field of research.
As the rotational speed of the rotor system is increased, an instability can be detected which is often referred to as ‘oil-whirl’ or ‘half-frequency-whirling’ in literature. As the frequency of this ‘whirling’ instability meets an eigenfrequency of the associated elastic rotor, its oscillation amplitudes increase tremendously which is also known as ‘oil-whip’. These ‘oil-whirl’ and ‘oil-whip’ effects can be rated as rather critical and should be avoided during the operation of the rotor system.
Various modifications (compared to the ‘classical’ cylindrical bearing) have been proposed in literature in order to suppress or at least to decrease these unwanted effects.
By applying a variable change in geometry of the supporting journal bearings, improvements of the rotor's dynamic behaviour are expected. Starting from an initially circular profile, the bearing is elastically deformed by an appropriate actuation mechanism which leads to a complex fluid-solid-interaction.
The effects of this change in geometry on the rotor system are studied by means of systematic stability and bifurcation analysis, focusing on time-efficient modelling methods.