The Non-Unicity of the Film Thickness in the Hydrodynamic Lubrication: Novel Approach Generating Equivalent Micro-Grooves and Roughness
More details
Hide details
University Moulay Ismail, ENSAM, Meknes, Morocco
Department D3, Prime Institute, UPR3346, University of Poitiers, France
Online publication date: 2021-08-26
Publication date: 2021-09-01
International Journal of Applied Mechanics and Engineering 2021;26(3):44-61
Since the 1960s, all studies have assumed that a film thickness “h” provides a unique pressure field “p” by resolving the Reynolds equation. However, it is relevant to investigate the film thickness unicity under a given hydrodynamic pressure within the inverse theory. This paper presents a new approach to deduce from an initial film thickness a widespread number of thicknesses providing the same hydrodynamic pressure under a specific condition of gradient pressure. For this purpose, three steps were presented: 1) computing the hydrodynamic pressure from an initial film thickness by resolving the Reynolds equation with Gümbel’s cavitation model, 2) using a new algorithm to generate a second film thickness, 3) comparing and validating the hydrodynamic pressure produced by both thicknesses with the modified Reynolds equation. Throughout three surface finishes: the macro-shaped, micro-textured, and rough surfaces, it has been demonstrated that under a specific hydrodynamic pressure gradient, several film thicknesses could generate the same pressure field with a slight difference by considering cavitation. Besides, this paper confirms also that with different ratios of the averaged film thickness to the root mean square (RMS) similar hydrodynamic pressure could be generated, thereby the deficiency of this ratio to define the lubrication regime as commonly known from Patir and Cheng theory.
Fatu A., Maspeyrot P. and Hajjam M. (2011): Wall slip effects in (elasto) hydrodynamic journal bearings.– Tribology International, vol.44, pp.868-877.
Gherca A.R., Maspeyrot P., Hajjam M. and Fatu, A. (2013): Influence of texture geometry on the hydrodynamic performances of parallel bearings.– Tribology Transactions, vol.56, pp.321-332.
Kanters A.F.C., Verest J.F.M. and Visscher M. (1990): On reciprocating elastomeric seals: calculation of film thicknesses using the inverse hydrodynamic lubrication theory.– Tribology Transactions, vol.33, pp.301-306.
Nikas G.K. and Sayles R.S. (2006): Study of leakage and friction of flexible seals for steady motion via a numerical approximation method.– Tribology International, vol.39, pp.921-936.
Fatu A. and Hajjam M. (2011): Numerical modelling of hydraulic seals by inverse lubrication theory.– Proc. IMechE, Part J: J. Engineering Tribology, vol.225, pp.1159-1173.
Crudu M., Fatu A., Hajjam M. and Cristescu C. (2013): Numerical and experimental study of reciprocating rod seals including surface roughness effects.– Sealing Technology, vol.6, pp.8-11.
Patir N. and Cheng H.S. (1978): An average flow model for determining effects of three-dimensional roughness on partial hydrodynamic lubrication.– ASLE Trans., pp.12-17.
Shen D. and Salant R.F. (2006): A transient mixed lubrication model of rotary lip seal with a rough shaft.– STLE Tribology Transactions, vol.49, pp.621-634.
Fowell M., Olver A.V., Gosman A.D., Spikes H.A. and Pegg I. (2007): Entrainment and inlet suction: two mechanisms of hydrodynamic lubrication in textured bearings.– ASME Journal of Tribology, vol.129, pp.336-345.
Fowell M.T., Medina S., Olver A.V., Spikes H.A. and Pegg, I.G. (2013): Parametric study of texturing in convergent bearings.– Tribology International, vol.52, pp.7-16.
Gumbel L. (1921): Verglieich der Ergebnisse der rechnerischen Behaudlung des lagerschmierungs problem mit neuren Versuchsergebnissen.– Monatsblätter d. Berlin, Bezirk V.D.I., pp.125-128.
Lahjouji I., El Gadari M., El Fahime B. and Radouani M. (2017): Effect of relative velocity between rough surfaces: hydrodynamic lubrication of rotary lip seal.– Int J Appl Mech Eng, vol.22, No.2, pp.321-332.
Journals System - logo
Scroll to top