A theoretical study of two‐dimensional grease flow in regions with discontinuities

Radulescu, A. V.; Bonneau, Dominique; Hajjam, Mohamed

doi:10.1002/ls.3010150206

Cited by 8 publications

(8 citation statements)

References 3 publications

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“…6 Several numerical and experimental investigations have reported the analysis of grease flow in various configurations. A theoretical analysis of two-dimensional (2D) grease flow through an asymmetric discontinuity has been performed by Radulescu et al 7 In numerical simulations, mostly computational fluid dynamics techniques have been used to investigate the grease flow. Lin and Meehan 8 reported the characterisation of degraded grease in axle roller bearings.…”

Section: Introductionmentioning

confidence: 99%

Thermal and multiphase flow simulations of polytetrafluoroethylene-based grease flow in restricted geometry

Raj

Sarkar

Pathak

2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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This work presents a numerical model for predicting flow behaviour and temperature distribution of polytetrafluoroethylene thickened grease in a roller bearing configuration of obstructed flow. A finite-element code with a laminar flow multiphase mixture model is used to predict the flow patterns and volume fraction distribution of a thickener in a rectangular channel with two cylindrical rollers rotating at constant angular speeds ranging from 50 to 200 r/min. A heat transfer analysis has been done to study the temperature variation near the rollers. Simulations are carried out for 5%, 10% and 20% concentrations of the thickener. Rheological characterisation of the proposed grease samples is done. An experimentally developed rheological model is incorporated in the numerical model. The rheological characteristics of the samples follow the Herschel–Bulkley model. The velocity profiles obtained from the present numerical model are compared with the nearest available experimental microparticle image velocimetry profiles for lithium complex grease to find qualitative similarity. The variation of volume fraction distribution and temperature at different times and locations of the channel is predicted. The rotation of rollers affects the local distribution of a thickener as well as the rate of homogenisation with the oil. As polytetrafluoroethylene grease is able to maintain its rheology even at elevated temperatures, most of the channel portion is thermally unaffected due to heat dissipation up to 5 W.

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Section: Introductionmentioning

confidence: 99%

Thermal and multiphase flow simulations of polytetrafluoroethylene-based grease flow in restricted geometry

Raj

Sarkar

Pathak

2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…It is clear from the experimental studies of brown grease pyrolysis that the product distribution is dependent on both the temperature and the heating profile [9,15,22]. Other experimental and theoretical studies on brown grease separation and flow have been performed [27,28].…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation of the Pyrolysis of Brown Grease

Almatarneh

Alnemrat

Omeir

et al. 2020

Journal of Chemistry

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The conversion of brown grease using pyrolysis reactions represents a very promising option for the production of renewable fuels and chemicals. Brown grease forms a mixture of alkanes, alkenes, and ketones at a temperature above 300°C at atmospheric pressure. This work is a computational study of the detailed reaction mechanisms of brown grease pyrolysis using DFT methodology. Prior experimental investigations confirmed product formation consistent with a set of radical reactions with CO2 elimination, as well as ketone by product formation, CO forming reactions, and formation of alcohols and aldehydes as minor byproducts. In this work, computational quantum chemistry was used to explore these reactions in greater detail. Particularly, a nonradical pathway formed ketone byproducts via the ketene, which we refer to as Pathways A1 and A2. Radical formation by thermal decomposition of unsaturated fatty acids initiates a set of reactions which eliminate CO2, regenerating alkyl radicals leading to hydrocarbon products (Pathway B). A third pathway (Pathway C) is an alternative set of radical reactions, resulting in decarbonylation and formation of minor byproducts. The results of the calculations are in good agreement with recent experimental studies.

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“…Mahncke and Tabor [22], and by Froishterer et al [12]. Radulescu et al [24] investigated the flow in pipes with discontinuities, which also could be applied to the flow in bearings. This work is a continuation of previous studies of the flow in closed straight channels [29,17] and in a 3D double restriction seal geometry [14,1,18].…”

Section: Introductionmentioning

confidence: 99%

Grease flow in an elbow channel

Westerberg

Farré-Lladós

et al. 2015

Tribol Lett

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Lubricating greases are materials characterized by a complex nonNewtonian rheology. This study is a continuation of previous studies on the coupling between grease rheology and grease flow in a straight channel-and concentric cylinder geometry. The problem has been modeled and validated with experiments. Here the flow in an elbow channel introducing a non-symmetric distribution of shear stress throughout the cross section of the channel elbow, as well as varying shear rates through the transition from the channel inlet to the outlet. The flow has been modeled both for higher flow rates and for creep flow. The influence of the grease rheology and flow conditions to wall slip, shear banding and an observed stick-slip type of motion observed for low flow rates are presented. The effect on the flow of the applied pressure is also investigated showing that the flow is sensitive to the pressure in the angular (ϕ) direction of the elbow. For high flow rates it is shown that flow separation occur with a resulting circulation in the elbow.

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A theoretical study of two‐dimensional grease flow in regions with discontinuities

Cited by 8 publications

References 3 publications

Thermal and multiphase flow simulations of polytetrafluoroethylene-based grease flow in restricted geometry

Thermal and multiphase flow simulations of polytetrafluoroethylene-based grease flow in restricted geometry

Mechanistic Investigation of the Pyrolysis of Brown Grease

Grease flow in an elbow channel

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