Paper 5: The Effect of Journal Misalignment on the Performance of a Journal Bearing under Steady Running Conditions

Abstract

A method of solution is described in which the governing equation is modified to account for variations in the oil-film thickness in the axial direction owing to journal misalignment. The position of the journal is specified by means of its eccentricity at its mid-length and by two parameters defining the extent and direction of the misalignment. The pressure distribution is evaluated numerically, and the direct load, friction torque, oil flow, and couple arising from the misalignment of the journal are obtained by numerical integration. A full range of journal misalignment conditions is examined for two length-diameter ratios. Results are presented in the form of non-dimensionalized graphs, showing the variation of direct load and misalignment couple with the journal misalignment parameters described. The angle between the line of action of the misalignment couple and the load line is evaluated in each instance, and graphs are presented to show the variation of the performance parameters for a particular degree of misalignment with the direction of application of the couple. Results for the particular instances in which the couple is in line with or at right angles to the load line are extracted, and these are compared with published experimental results of other workers. Good agreement is obtained, and moreover it is shown that, in general, these are not the two extremes of misalignment. For these two conditions design charts are presented, whereby, from knowledge of the applied couple and direct load, the degree of misalignment and the resultant peak pressure parameter may be determined. Charts which illustrate the reduction in load capacity for a particular journal misalignment in the plane of the load are also presented. General validity is claimed for this method of exploring a relatively unexamined subject, and the results are considered by the authors to be a useful improvement on those obtained by previous analytical workers.

Dynamic Stability of Linear Misaligned Journal Bearings Via Lyapunov's Direct Method©

“…Equations [15] a n d [I61 for JI, = JI, = 0 are compared with the determinants for the aligned case of El-Marhorny (9) to test the correctness of the method described abovc a n d are found to be in absolute agreement.…”

Analysis of Misaligned Grooved Journal Bearings

“…The approach taken in reference [5] is used to represent the fluidfilm thickness under a general misaligned condition. For a circular bearing the parameters describing the film thickness representation are shown in Fig.…”

“…Asanabe, et al in [3] made a more ambitious attempt at solving a two axial-groove bearing but they restricted themselves to misalignment in the vertical plane only; worse, they used the Sommerfeld boundary conditions in the solutions of the differential equation. By far the most satisfactory contribution is that of Smalley and McCallion [5], which following the methods of [4], gives a thorough discussion of bearing misalignment at L/D = 0.5 and 0.75. Their solutions, however, are all for a full ungrooved bearing.…”

“…(5) may be written in matrix form wherein the coefficient matrix is banded. The resulting form is then suitable for rapid solution by means of a Gaussian elimination technique [7j.…”

Thermal Analysis of Elliptic Bore Journal Bearing Considering the Effect of Shaft-Misalignment

“…Initially, there is the need of estimating the effect of journal misalignment on the performance under steady state running condition 12) . The cavitation and grooving also determines the degree of misalignment 13) .…”