A Study on Stability Characteristics of Externally Pressurized Noncircular Air-Lubricated Journal Bearings

An experimental study is performed for investigating the threshold of whirl instability of the rigid rotor supported by two externally pressurized air-lubricated journal bearings. Three types of bearings, that is, 3-lobe, 4-iobe and circular bearing s, of 40 mm diameter and 40 mm length are tested. The rotor rotates horizontally and air supply pressure varies from 0.098 MPa to 0.49 MPa. The effect of supply pressure and radial load, which is applied to the rotor by means of an electromagnet, from 8.1 IN to 32.6 IN with constant rotor mass on the threshold of whirl instability are discussed. It is shown that the noncircular bearing is effective for the prevention of whirl instability.