Geometrical Design Considerations on Externally Pressurized Porous Gas Bearings

This study investigates the influences of geometrical effects on the performance of a finite length porous journal bearing fed by externally pressurized air. The analysis in this study considers three geometrical parameters, L/D, H/D, and C/R, as the main influence factors. A quasi-linear numerical scheme associated with an underrelaxation factor is used to solve for the pressure solutions of the nonlinear coupled partial differential equation (PDE). Results show that the porous journal bearing exhibits a significant aerodynamic lubrication action when L/D epsilon 1, H/D epsilon 0.1, and 0.0005 C/R 0.001. This study recommends L/D = 1 and C/R = 0.001 as optimum design criteria for the bearing aspect ratio and clearance ratio, respectively, as far as bearing load and whirling instability are concerned. Because greater porous thickness does not improve the bearing load capacity, this study suggests H/D = 0.1 as a proper porous thickness.