The role of axial edge effects and cavitation in lubrication for short journal bearings

Questions concerning the role of axial edge effects in short bearing theory are investigated using the method of matched asymptotic expansion applied to Reynolds lubrication equation. Attention was initially directed to this problem by other studies that indicate regions of nonconformity in the short bearing solution (i.e., small length to diameter ratio). In the present theory a matched asymptotic expansion method-using the bearing slenderness ratio as the small parameter-is appied to journal bearings. The axial inlet fluid film edge and axial cavitation boundary layers are examined. The axial boundary layers are shown to scale on the bearing slenderness ratio; these boundary layers are necessary to adjust the pressure to the prescribed boundary value. Cavitation boundary shapes, as determined from Reynolds’ free surface condition, are shown to be independent of the bearing eccentricity ratio. A reduction in load capacity-relative to previous theories-is shown. Pressure profiles obtained by the present theory are compared to previously reported short bearing results.