Experimental studies on low-frequency vibration

which are apt to happen on the gas bearing turbo-expander in the air refrigerator system for the airplanes

are carried out in this paper.Tests are conducted at various journal bearing supply pressure and run-rate to research the characteristics of low-frequency vibration i.e.gas-film whirl and gas-film whip.The experimental results verify the impact of low-frequency vibration on stability

and appropriate bearing supply pressure and run-rate can abate and eliminate the low-frequency vibration.More importantly

the results reveal the relationship between low-frequency vibration and the mechanical efficiency of rotor-bearing system

and an effective calculation equation is proposed.