Hydrodynamic Performance of Elastically Supported Gas-Lubricated Foil Journal Bearings

摘要

Elastically supported gas-lubricated foil journal bearings are promising application to high-speed turbo-machinery like a micro gas turbine, because of small frictional loss and maintenance free operation and so on. The bearing is constructed with a flexible circular top foil supported by a corrugated bump foil and has a larger load-carrying capacity, compared with rigid surface gas bearings, as an appropriate wedge is formed due to the deformation of the foils. This study aims at predicting the hydrodynamic performance of the bearing numerically. The compressible iso-viscous Reynolds equation and the deformation equation of the top foil, linked with the expression of the gas film thickness, are solved simultaneously for the steady-state performance of the bearing. It is found that there are seven dimensionless design variables and four of them, that is, the attached position of the foils, the angular extent and the thickness of the top foil and the equivalent spring constant of the bump foil have a strong influence on the load-carrying capacity.