Experimental Investigations on Vibration Characteristics for Bearing-Rotor System of Micro Gas Turbine

The dynamic characteristics of the rotor-bearing system for micro-gas turbine are the key factors that affect the safe and stable operation of the micro-gas turbine. This paper carried out the experimental investigations on the vibration characteristics during the speed-up process of rotating shaft, based on rotor structure of micro gas turbine generator supported by aerostatic bearings. Rotor vibration characteristics during conical whirling critical speed area, mixed control area, surge area, self-holding speed area, and bending critical speed area were analyzed. Simultaneously effects of bearing supply pressure and radial clearance on the shaft vibration characteristics were studied by experiments. The results showed that the ignition fuel flow has stepped increase when the ignition fuel valve was opened, which caused easily the rotor and bearing rubbing. And the reasonable bearing radial clearance and gas supply pressure can effectively restrain the occurring of the low frequency whirling and gas film oscillation, and improve the bearing-rotor system stability.