Abstract
This paper describes the design and characteristics of a tape-type radial foil bearing for ultra-small gas turbine generators. A tape-shaped foil made of stainless steel (SUS304) is wrapped three times around a rotor, and then fixed in a housing. The outer and middle coil segments of the foil have some etched grooves so that they deform as leaf spring shapes in the housing. These springs support the inner coil segment of the foil, i.e. bearing foil, elastically. We designed the bearing geometry, and theoretically estimated the stiffness of the foil spring. We also measured the stiffness of the foil spring, and confirmed that the calculated and measured values fairly matched. Using the obtained stiffness, pressure distribution in the bearing clearance was simulated by divergence formulation (DF) method. Based on this result, we designed and produced a tape-type radial foil bearing test rig with a Ti-6Al-4V rotor of 8 mm in diameter. The test rig stably rotated at 430000 rpm, which was limited by the performance of the turbine.
