2915 Study on Aerodynamic Foil Bearing for Ultra-Micro Turbomachinery

Recently, in high speed turbo-machinery, the following demands have been strongly increasing such as miniaturization of various components, high speeds and high durability under high temperature environment An aerodynamic foil bearing is one of candidates to satisfy the above requirements. This paper proposes a new type of foil journal bearings using hemi-spherical bumps to make a small sized turbo-machine for high speed rotation. The proposed foil bearing has three layers of foil sheet The bottom and middle sheets have many hemi-spherical bumps to flexibly support the smooth top foil. Experimental investigations were conducted to confirm (he stability of a rotor with 6mm diameter supported by two proposed foil journal bearings. As a result, it was confirmed that the proposed bearing could stably rotate up to 600,000 rpm.