Effect of form errors on oil film characteristics of hydrodynamic journal bearings based on small displacement torsor theory
Industrial Lubrication and Tribology
ISSN: 0036-8792
Article publication date: 4 December 2018
Issue publication date: 3 April 2019
Abstract
Purpose
This paper aims to investigate how form error of journal affects oil film characteristics, which are composed of several parameters including the maximum film pressure, film moment, frictional coefficient and carrying-load capacity.
Design/methodology/approach
A new generalized equation based on the small displacement torsor theory is derived, as well as its capability of representing types of form error on the journal, using four specified parameters in a three-dimensional (3D) state. Based on the new generalized equation of form errors, the Reynolds equation is represented and solved numerically using the Swift–Stieber boundary condition.
Findings
The results show that the form errors of journal have significant influence on all oil film characteristics. However, the film moment remains nearly unchanged as film characteristics, especially eccentricity ratio, become large. All film characteristics investigated vary periodically as the form error. More importantly, it is found that the film pressure distribution transforms to an asymmetric shape along the axial direction of the bearing, no longer a symmetric shape in the case of two-dimensional (2D) form errors. It is necessary to substitute the 3D form error model, which takes the variations of the film characteristics in axial direction into account, for the 2D model in the designing stage of journal bearings.
Originality/value
First, the effect of the form error of the journal on the performance of hydrodynamic journal bearings is studied in the view of the film characteristics systematically. Secondly, the new generalized equation of form error, derived by SDT theory, is capable of representing any types of form error on the journal, not only representing one type of form error merely.
Keywords
Acknowledgements
Funding: The authors gratefully acknowledge the financial supports from the National Natural Science Foundation of China (NSFC) under the project No. 51265004, No. 50865001, No. 51105084, and Guangxi Natural Science Foundation under the project No. 2011GXNSFF018004.
Citation
Ma, X., Xu, W., Zhang, X. and Yang, F. (2019), "Effect of form errors on oil film characteristics of hydrodynamic journal bearings based on small displacement torsor theory", Industrial Lubrication and Tribology, Vol. 71 No. 3, pp. 426-439. https://doi.org/10.1108/ILT-05-2017-0140
Publisher
:Emerald Publishing Limited
Copyright © 2018, Emerald Publishing Limited