ELASTOHYDROSTATIC STUDY OF 6-POCKET JOURNAL BEARING SYSTEM

Abstract

Hydrostatic/Hybrid journal bearing system supporting heavy loads are subjected to high fluid film pressure. These high fluid film pressure deforms the bearing shell which in turn modifies the fluid film thickness profile. Thus the bearing performance charac-teristics gets 6 ffected due to bearing shell flexibility. Therefore the bearing performance characteristic data generated by taking the assumption that both bearing shell and journal are absolutely rigid may not be more accurate. Therefore the effect of bearing shell flexibility should be included in the analysis to predict the performance characteristics of 6-pocket and 4-pocket journal bearing more realistically. The present work is aimed to analyze the performance of a capillary compensated 6—pocket hydrostatic journal bearing considering bearing shell flexibility into account and comparing its performance with bearing having 4-pockets for the same bearing geometric and operating parameters. The EHS analysis involves simultaneous solution of Reynold's equation and system equation coupled with equation of flow through restrictor as a constraint and the elasticity equation for the deformation of bearing shell. Lubrication and elasticity equation is to be obtained by using the finite element method and a suitable iteration scheme. In case of journal bearing centre coordinates an additional overall iterative loop is needed to establish the equilibrium position of journal centre for a specified vertical load support. The static characteristics in terms of the minimum film thickness, total lubricant flow, attitude angle, dynamic performance characteristics in terms of four stiffness coefficient's, four damping coefficient's and threshold speed are iii to be studied for both hydrostatic/hybrid mode of operation of bearing. The effect of bearing shell flexibility on the performance characteristics have been studied for several values of deformation coefficient (Cd 0.0 to 1.0) and for non-dimensional load (W = 0.0 to 1.0). 0 iv