CHAIR OF

MULTIBODY

DYNAMICS

In the area of high-speed turbomachinery, oil-free bearing concepts are coming to the front due to the desired mobility and energy transition, which also requires charged fuel cell systems in particular.
Air-lubricated bearings are suitable here due to their many advantages: No need for an external lubricant supply; low losses due to friction power; inert lubricant, which is why expensive seals can also be dispensed with in fuel cells. On the other hand, there are disadvantages such as the low load-bearing capacity and the excitation of subsynchronous vibrations specific to journal bearings.
The load capacity can be increased by various concepts, but mainly by a flexible bearing shell in the form of a foil structure, whereby the focus of the research project is on bump-type bearings.
The prediction of the subsynchronous vibrations mentioned above is of great importance in the development process of rotordynamic systems, as these vibrations can have negative effects such as acoustic irregularities, rubbing of the rotor on the housing or contact in the bearing and must therefore be avoided or at least minimized in amplitude.

The research project aims to develop, implement and experimentally validate an efficient simulation method for rotors with air bearings that allows a valid prediction of the subsynchronous vibrations and the associated stability, taking into account the hydrodynamics of the air gap, the deformation of the foil structure and the thermodynamic effects in the radial air bearings. The integration into an overall rotordynamic simulation also makes it possible to take into account the time-dependent rotor misalignment and its influence on the bearing damping in the bearings and thus to predict the vibration amplitudes and the occurrence of potential instabilities with high quality.

View project in the research portal