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Sharma S.C.,Indian Institute of Technology Roorkee | Ram N.,Indira Gandhi Institute of Engineering and Technology
Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2012 | Year: 2012

The influence of surface roughness on the performance of fluid film bearings has attracted the attention of several researchers in recent times. Usually, the design of hole-entry journal bearing is based on the assumption that both the journal and bearing surfaces are perfectly smooth, however in industrial applications all bearing surfaces are rough to some extent. Thus, the assumption of a smooth bearing surface is not valid for the accurate prediction of the bearing performance. As a consequence of this, the performance of journal bearings gets affected. Further, the lubricant used to lubricate the bearings is additized in order to improve their performance. Lubricant containing a suspension of particles having individual motion, no longer exhibit Newtonian behavior and is characterized as micropolar lubricants. In the present study, the lubricating oil used to lubricate the hole-entry journal bearing has been modeled as micropolar lubricant. The average modified Reynolds equation for micropolar lubrication has been solved by using the Finite Element Method. The study indicates that for a rough bearing lubricated with micropolar lubricant, the value of minimum fluid film thickness is more vis-a-vis smooth bearing lubricated with Newtonian lubricant. Source


Ram N.,Indira Gandhi Institute of Engineering and Technology | Sharma S.C.,Indian Institute of Technology Roorkee
Society of Tribologists and Lubrication Engineers Annual Meeting and Exhibition 2012 | Year: 2012

The use of non-Newtonian lubricants has received greater attention due to the requirement of modern machine elements. The addition of small amount of long chain polymer solutions to the Newtonian lubricants gives the most desirable lubricating performance. The classical theory of Newtonian fluids neglect the size of fluid particles, it fails to describe the behavior of non-Newtonian fluids such as polymer thickened oils, lubricants with various additives, synthetic and bio-fluids. The lubricants containing long chain polymer molecules can be represented by couple stress lubricant. In the present study, the performance of constant flow valve compensated hole-entry hybrid journal bearing operating with couple stress lubricant has been presented analytically. The modified Reynolds equation based on Stoke's couple stress fluid theory has been solved by using the Finite Element Method. The numerically simulated results have been presented for various valves of couple stress parameters. The numerically simulated results reveal that the value of minimum fluid film thickness is higher for a bearing lubricated with couple stress lubricant vis-a-vis the Newtonian lubricant. Source

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