ANALYSIS OF THREE-LOBE HYDRODYNAMIC POROUS JOURNAL BEARING

Abstract

Suitability for applications where oil feeding is difficult, low cost and relatively better control over dimensional accuracies in manufacture, to name of a few, are the advantages which have made porous bearings increas-ingly popular among; lubrication engineers. Ever since the first theoretical work of Morgan and Cameron, a considerable amount of work has been published on static as well as dynamic performance characteristics of porous hydrodynamic and externally pressurised bearings with both incompressible and compressible lubrication. All the work on porous journal bearings has however been confined to circular j ours al bearings. The present work is a breakthrough in porous bearing literature. This work presents the analysis of three-lobe porous hydrodynamic journal bearing for its static and dynamic performance characteristics. The static characteristics include load support, friction power loss and oil losses of the bearing. The dynamic characteristics are described in terms of stiffness and damping coefficients and stability margins of linearized system in terms of critical mass of the journal. The computed results of the performance characteristics are for a fairly wide range of permeability parameters and illustrate the effect of porosity on three-lobe bearing (iv) performance. The nonlinear analysis indicates that the stability margins of linearized system are not reliable enough for the design of three lobe porous journal bearing system. More comprehensive data, based on nonlinear analysis, are required to establish the exact stability margins of the journal bearing system. The analysis of the bearing is entirely general and can be applied to circular two-lobe and also the pivoted pad porous as well as non-porous bearing configurations.