That is the project in which I am a manager (financed by the National Center for Research and Development, the project budget is PLN 1,200,000).
Foil bearings have recently become more commonly used. They are widely used, among others in aircraft engines, and more and more often in small power turbines. Under some operating conditions, they are the only bearing system that can be used. Foil bearings can be chosen as components of machines operating at very high rotational speeds and temperatures. However, there are some technical problems associated with the operation of such bearings, for example, such as a difficult start due to the pre-clamp of foils or a high vibration amplitude occurring at the nominal speed, which results from a compliant supporting layer, a gaseous lubricating film and the load-bearing layer of the foil. All these problems can be solved by applying an active control of the size of the sleeve, which is the subject of this project. Increasing its size during the start-up of the rotor will reduce wear of the load-bearing foil, reduce the starting torque, which may eliminate the need for an additional drive when a machine equipped with foil bearings is started up. Active control of changes in the geometry of a foil bearing (during its operation) will enable smoother passage through a resonance, better compensation of temperature fluctuations, and also better adjustment of operating parameters in a wide range of rotational speeds. If such a method of control is used bearings will unquestionably (be able to) run more safely.
Active foil bearings are currently not available on the market. The work on such bearings will constitute a follow-up to the research conducted since many years by the IMP PAN team, and the proposed technical solutions are unique.