Experimental study on bump foil gas bearing with different diametric clearance configurations
The stability characteristics of a 25 mm rotor turboexpander with bump foil journal gas bearing pairs and a pair of pressurized thrust bearing are investigated in this study. The journal gas bearing pairs in various inner diameters supply radial support for the rotor with different hydrodynamic gas film thicknesses, and the pair of pressurized thrust bearings balances the axial forces. The experimental results reveal that the stability of the bump foil gas bearing is achieved over a wide range of diametric clearances and that an optimal nominal diametric clearance exists, thus resulting in high rotation speed with small vibration amplitudes. The maximum turboexpander speed reached 93.3 krpm under the nominal diametric clearance of 0 um with a maximum synchronous amplitude of less than 20 um.