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TECHNICAL PAPERS

The Impact of the Cavitation Model in the Analysis of Microtextured Lubricated Journal Bearings

[+] Author and Article Information
Roberto Ausas

 Centro Atómico Bariloche, 8400 Bariloche, Argentina; Instituto Balseiro, 8400 Bariloche, Argentinarfausas@gmail.com

Patrick Ragot

RENAULT, Direction de l’Ingeniere Mecanique, Service Mecanique des Solides et Thermique (66151), F-92508 Rueil Malmaison, Francepatrick.ragot@renault.com

Jorge Leiva

 Centro Atómico Bariloche, 8400 Bariloche, Argentina; Instituto Balseiro, 8400 Bariloche, Argentina

Mohammed Jai

Mathématiques, INSA de Lyon, CNRS-UMR 5208, Bâtiment Leonardo da Vinci, F-69621 Villeurbanne, Francemohammed.jai@insa-lyon.fr

Guy Bayada

Mathématiques, INSA de Lyon, CNRS-UMR 5208, Bâtiment Leonardo da Vinci, F-69621 Villeurbanne, France; LAMCOS,  INSA de Lyon, CNRS-UMR 5259, Bâtiment Leonardo da Vinci, F-69621 Villeurbanne, Franceguy.bayada@insa-lyon.fr

Gustavo C. Buscaglia

 Centro Atómico Bariloche, 8400 Bariloche, Argentina; Instituto Balseiro, 8400 Bariloche, Argentina; ICMC, Universidade de São Paulo, 13560-970 São Carlos, São Paulo, Brazilgustavo@cab.cnea.gov.ar

J. Tribol 129(4), 868-875 (Apr 12, 2007) (8 pages) doi:10.1115/1.2768088 History: Received November 02, 2006; Revised April 12, 2007

In this paper, we analyze the impact of the cavitation model on the numerical assessment of lubricated journal bearings. We compare results using the classical Reynolds model and the so-called p-θ model proposed by Elrod and Adams [1974, “A Computer Program for Cavitation and Saturation Problems  ,” Proceedings of the First LEEDS-LYON Symposium on Cavitation and Related Phenomena in Lubrication, Leeds, UK] to fix the lack of mass conservation of Reynolds’ model. Both models are known to give quite similar predictions of load-carrying capacity and friction torque in nonstarved conditions, making Reynolds’ model the preferred model for its better numerical behavior. Here, we report on numerical comparisons of both models in the presence of microtextured bearing surfaces. We show that in the microtextured situation, Reynolds’ model largely underestimates the cavitated area, leading to inaccuracies in the estimation of several variables, such as the friction torque. This dictates that only mass-conserving models should be used when dealing with microtextured bearings.

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Copyright © 2007 by American Society of Mechanical Engineers
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Figures

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Figure 1

Pressure fields predicted by Reynolds’ and Elrod and Adams’ p-θ model for the one-dimensional textured thrust bearings considered. Left: Case 1 (uniform texture depth across the domain). Right: Case 2 (nonuniform texture depth across the domain). The boundary condition imposed in both cases is p(0)=p(1)=10−3. (a) The nondimensional bearing profiles. (b) Pressure fields predicted by Reynolds’ model. (c) Pressure fields predicted by Elrod and Adams’ model.

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Figure 2

Schematic view of the two-dimensional parallel thrust bearing with spherical dimples, together with the boundary conditions and parameters considered

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Figure 3

Pressure profiles along the line passing through the dimples’ centerpoints for the parallel thrust bearing with spherical dimples. Dashed line: Reynolds’ model. Continuous line: Elrod and Adams’ p-θ model. The detail shows the behavior of the pressure fields near the rupture and re-formation boundaries.

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Figure 4

Schematic representation of the journal bearing and the corresponding two-dimensional domain

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Figure 5

Comparison between the Reynolds model and the p-θ model for the flow rate Q through lines of constant x2 for a smooth bearing and a textured one

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Figure 6

3D view of pressure field as obtained with (a) the Reynolds model for the smooth bearing, (b) the p-θ model for the smooth bearing, (c) the Reynolds model for the textured bearing, and (d) the p-θ model for the textured bearing. The bearing parameters are as in Fig. 5. Maximum values are p≃0.15 for all cases.

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Figure 7

Effect of the model choice on the pressure profile along the line x2=B∕2 for the cases studied in Fig. 5. (a) Comparison in the smooth case. (b) Comparison considering an array of 50×5 texture cells.

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Figure 8

Cavitated regions (in gray) corresponding to the different cases considered in Fig. 5. The texture depth was taken as h0=0.3 and the area fraction as s=20%.

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Figure 9

Friction torque T as a function of the applied load Wa for different values of the texture depth h0. Area fraction s=20%. (a) Reynolds’ model; (b) p-θ model.

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