HYBRID PERFORMANCE OF MISALIGNED JOURNAL BEARING SYSTEM WITHOUT PRESSURE CHAMBERS BETWEEN BEARING SURFACES

Abstract

The journal misalignment in hole-entry hybrid journal bearing may be caused, most commonly, by non-central loading, a moment produced by couple forces on the journal, shaft deflections due to elastic' and thermal distortions and assembly errors. This journal mise.1 r.►eent modifies the fluid film thickness in both circumferential and axial directions of the bearing. Thus the bearing performance characteristics gets affected due to the journal misalignment. Therefore, the analysis based upon the assumption of parallel axes do not yield accurate results. For an accurate prediction of bearing performance characteristics it is very essential to include journal. misalignment in the analysis. The present work is aimed to analyze the performance characteristics of capillary compensated hole-entry hybrid journal bearing considering journal misalignment into account Tnd comparing its performance characteristics with aligned hole-entry hybrid journal bearing for the same bearing geometric and operating parameters. the analysis involves computation of fluid film thickness which varies along circumferential and axial co-ordinates due to journal misalignment and simultaneous solution of Reynold's equation along with equation of lubricant flow through restrictor as a constraint. The finite element method employir~.g Galerkin's technique has. been used to solve Reynold's equation with proper boundary •.onditions. Further, the misalignment parameters have been specified in terms of Eulerian angles having first rotation (a-) about bearing fixed, X-axis and the second rotation (8) about the journal fixed Z'-axis. The journal has been allowed to iii misalign on a axial plane containing load vector and on a plane perpendicular to axial plane containing load vector. For the symmetric hole-entry journal bearing, the static performance characteristics in terms of minimum fluid film thickness, total bearing flow, mid-plane attitude angle, misaligning mcn nts, dynamic perfor:i2.nce characteristics in terms of stiffness coefficients, damping coefficients and threshold speed have been studied for both hydrostatic and hybrid modes of operation of bearing. Those performance characteristics have been studied for selected .valves of misalignment parameters (a-,5) for non- dimensioial load (Wo) and/or restrictor design parameters (C 9). s~ Finally, the effect of journal misalignment on performance characteristics of asymmetric hole-entry hybrid journal bearing has been studied and compared with symmetric hole-entry hybrid journal bearing for both hydrostatic and hybrid mode of operation of bearings, for several values of restrictor design parameter (Cs2) with constant external load (W ), 0 iv