Improvement of Bearing Characteristics of Hydrostatic Gas Journal Bearing with Asymmetric Gas Supply

(Reduction of Rotor Vibration by Supply Gas Pressure Control)

Abstract

Hydrostatic gas journal bearings can contactlessly support rotors by gas pressure. They provide advantages such as high precision rotation, high speed rotation and low friction loss. However, the load capacity of gas bearings is very small in comparison with rolling contact bearings, so they have been mainly applied to small size rotating machinery. In order to support heavier rotors and unbalanced rotors, we have developed an asymmetric gas supply system for the bearing. The system is supplied different gas pressure to the bearing from multiple supply holes in accordance with rotational state of the rotor. A test rig was fabricated by authors and a rotating test was carried out to verify the advantageous. The test bearing has diameter of 60 mm and the length of 120 mm. The results of the numerical simulation using non-linear orbit method was compared with the test results. Each approaches showed that the asymmetric gas supply system can be reduced the rotor vibration compared with the conventional symmetric gas supply system.