Rotordynamic characteristics of a micro turbo generator supported by air foil bearings

Abstract

The rotordynamic characteristics of a micro power system supported by air foil bearings were investigated. Stability analysis was performed by a finite element method with the predicted dynamic coefficients of the foil bearings. A preliminary test rig was developed to simulate the operating characteristics of the micro power system. It consisted of a rotor supported by two air foil journal bearings and two air foil thrust bearings, and an impulse driven turbine. The foil journal bearings had a diameter of 7 mm and a length of 7 mm (L/D = 1). The test rig was operated stably under various situations and speeded up to 300 000 rpm. The main portion of the rotor response was synchronous and the amplitude of synchronous vibration was about 5 - 20 mu m. Further, theoretical and experimental results for the unbalance response were compared. From this study, we showed the possibility of stable performance for the micro power system supported by air foil bearings.