Experimental and theoretical analysis of the stability behaviour of a rigid rotor supported by conical gas foil bearings

With the ability to support radial and axial loads simultaneously, conical gas foil bearings (CGFBs) offer the potential to halve the number of bearings required in a rotor system supported by conventional gas foil bearings (GFBs). This paper presents the first experimental results for a rigid rotor fully supported solely by two opposing CGFBs. A new method of measuring the reaction torque of the bearing housing is used to experimentally verifying the functionality of the bearing prototypes. Furthermore, the experimentally observed stability behaviour for different bearing clearances shows good agreement with the predictions of a presented theoretical model. The onset speed, frequency, and shape characteristics of the measured sub-synchronous vibrations can be predicted to a large extent. Finally, the theoretical model presented is used to perform a parameter study analysing variations of selected bearing design parameters. • A rigid rotor can be fully supported by two opposing conical gas foil bearings. • The functionality of conical gas foil bearings can be validated experimentally. • Sub-synchronous vibrations can be predicted by a fully coupled non-linear model.