Abstract: Based on the single deck protuberant foil gas bearing，a new type of foil bearing composed of multidecked structure was proposed. The relative position of the protuberant of different decks arranged to produce variable stiffness and damping effects.This new configuration possesses controllable stiffness in axial and circumferential direction，as well as the additional coulomb damping between the stacked layers， could improve the bearing stability.In the experiment， the maximal running speed of the 25mm diameter rotor in the turboexpander reached 99044 r/min. In the whole speed up and down processes， the amplitude of subsynchronous whirl is small which verifies the suppression effect of the new configuration， therefore， this new foil bearing can be applied in high speed turbomachinery.

Key words: gas bearing, blister foil, multidecked structure, controllable stiffness, high speed turbomachinery