Axial wedge effect in tilted hydrodynamic journal bearings

Abstract

Hydrodynamic journal bearings are susceptible to static angular misalignment, resulting from improper assemblage, elastic and thermal distortion of the shaft and bearing housing, and also manufacturing errors. Several previous works on the theme, both theoretical and experimental, focused on the determination of the static properties of angular misaligned bearings. Although some reports show agreement between theoretical and experimental results, the increasingly severe operating conditions of hydrodynamic bearings (heavy loads and high rotational speeds) require more reliable theoretical formulations for the evaluation of the journal performance during the design process. The consideration of the angular misalignment in the derivation of the Reynolds equation is presented here in detail, showing that properly conducted geometric and magnitude-order analyses lead to the inclusion of an axial wedge effect term that influences the velocity and pressure fields in the lubricant film. Numerical results evidence that this axial wedge effect more significantly affects the hydrodynamic forces and static operational properties of tilted short journal bearings.