Sleeve dampers for externally pressurised gas journal bearings

An approximate small eccentricity analysis is presented, for finding the threshold of fractional speed whirl instability of an unloaded double plane admission hybrid gas journal bearing supported by a non-rotating externally pressurised gas journal bearing sleeve damper. A line source is assumed at the feeding planes to the gas film with flow and load correction factors to account for the discreteness of the feed holes (details of these factors are presented in a related publication). The results show that, by careful selection of the design parameters, it is possible almost to remove fractional speed whirl instability from the bearing arrangement. Some practical designs of sleeve dampers are also presented.