On 18 September 2025, junior researcher Kristóf Szombati from LUT University presented the study “Dynamics of a magnetically-levitated vertical rotor under touchdown bearing contacts induced by platform motions – an experimental investigation” at the Vibrations in Rotating Machinery (VIRM) conference in London. The work, developed jointly by LUT University and the Technical University of Denmark (DTU), contributes to advancing knowledge in one of MARPOWER’s key areas: the application of active magnetic bearings (AMBs) for rotating machinery, supporting the project’s ambition to develop an advanced, gas-turbine-based energy conversion system designed to run on sustainable fuels such as green methane, green methanol, hydrogen, and ammonia.
Investigating rotor dynamics on moving platforms
One of the key innovations of the MARPOWER Energy Conversion System is the integration of low-friction active magnetic bearings (AMBs). These bearings reduce mechanical losses, enhance reliability, and extend the lifespan of key components, ensuring smooth operation and minimizing maintenance needs. Investigating their performance under realistic conditions is therefore essential, and Kristóf’s study directly supports the refinement and validation of this technology for future marine applications.
The study presented at VIRM examines how a vertical rotor supported by AMBs behaves when exposed to platform motions that lead to touchdown bearing (TDB) contacts. These moving platforms are used to simulate real-life operating conditions, such as those experienced at sea, where machinery is continuously affected by waves and vessel motions.
In the experimental setup, the rotor operates at 8000 rpm while the base undergoes tilting excitation. The results show that platform motion can trigger actuator saturation and repeated contact with the touchdown bearings. Each contact event, lasting about 0.15 seconds, follows a sequence: the rotor briefly enters a backward whirl, transitions into a forward whirl, and is then stabilized by the controller.
The study concludes that the system is able to recover stability after contact events, but the interaction between the rotor and the touchdown bearings needs further investigation. To build on these findings, the researchers plan to develop models of rotor–TDB contact using established friction and normal force approaches, enabling more accurate prediction and design for future applications.
Strong interest at an international forum
The presentation drew around 70 participants from academia, research, and industry, who showed strong interest in the topic. Reflecting on the discussion, Kristóf noted: “I received several questions after my talk, and some of them were directly relevant for MARPOWER. From this perspective, I learned that we should define a lifetime or contact number limit for the touchdown bearings before they must be changed, and also make sure that no bearing locking happens in case of contact. This showed me that the audience was not only engaged, but also thinking ahead about how our findings could be applied in practice”.
The VIRM conference, organized by the Institution of Mechanical Engineers, has since 1976 gathered international experts to exchange the latest advances in rotor dynamics, vibration control, and rotating machinery technologies. It provided an ideal platform for MARPOWER partners to showcase their research to a global community.