A Numerical Solution to the Elasto-Hydrodynamic Problem

The paper presents a mixed thermo-hydrodynamic analysis of elliptic bore bearings using combined solution of Navier-Stokes, continuity and energy equations for multi-phase flow conditions. A vapour transport equation is also included to ensure continuity of flow in the cavitation region for the multiple phases as well as Rayleigh-Plesset to take into account the growth and collapse of cavitation bubbles. This approach removes the need to impose artificial outlet boundary conditions in the form of various cavitation algorithms which are often employed to deal with lubricant film rupture and reformation. The predictions show closer conformance to experimental measurements than have hitherto been reported in the literature. The validated model is then used for the prediction of frictional power losses in big end bearings of modern engines under realistic urban driving conditions. In particular, the effect of cylinder deactivation (CDA) upon engine bearing efficiency is studied. It is shown that bigend bearings losses contribute to an increase in the brake specific fuel consumption with application of CDA contrary to the gains made in fuel pumping losses to the cylinders. The study concludes that implications arising from application of new technologies such as CDA should also include their effect on tribological performance.

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“…A density model proposed by Dowson and Higginson [37], modified for temperature variation by Yang et al [38] provides:…”

Section: Lubricant Rheologymentioning

confidence: 99%

Big End Bearing Losses with Thermal Cavitation Flow Under Cylinder Deactivation

et al. 2015

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“…Dirichlet boundary conditions apply to Eqs. (1) and (2) such that pressure at the global inlet (p a ) and outlet (p b ) is zero (ambient pressure):…”

Section: Fluid Flow Modelmentioning

confidence: 99%

“…The Reynolds equation [1] is well established as an accurate means of describing fluid flow in the Elastohydrodynamic Lubrication (EHL) of smooth surface geometries [2].M o r er e c e n t l yt h e focus of lubrication engineers has been directed toward analysis of surface topography and the influence that this has on bearing load capacity and friction coefficients [3]. The potential of topographical features to improve bearing performance has increased the importance of surface roughness and texturing within bearing design [4].…”

Section: Introductionmentioning

confidence: 99%

Two-scale EHL: Three-dimensional topography in tilted-pad bearings

Boer

Hewson

Thompson

et al. 2014

Tribology International

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Derived from the Heterogeneous Multiscale Methods (HMM), a two-scale method is developed for the analysis of Elastohydrodynamic Lubrication (EHL) and micro-EHL in tilted-pad bearings with threedimensional topography. A relationship linking the pressure gradient to mass flow rate is derived and represented in the bearing domain through homogenisation of near-periodic simulations describing the Fluid Structure Interaction (FSI) of topographical features. For the parameters investigated the influence of compressibility and piezoviscosity was found to be more significant than that of non-Newtonian (shear-thinning) behaviour on textured bearing performance. As the size of topography increased twoscale solutions demonstrated that at constant load the coefficient of friction increased and the minimum film thickness decreased over a range of pad lengths and tilt angles.

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“…(27). Therefore, a quasi-static load balance must be sought between the contact load carrying capacity, comprising asperity load share and any hydrodynamic lubricant reaction against the applied load, thus:…”

Section: The Numerical Modelmentioning

confidence: 99%

Surface specific asperity model for prediction of friction in boundary and mixed regimes of lubrication

et al. 2016

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Machine downsizing, increased loading and better sealing performance have progressively led to thinner lubricant films and an increased chance of direct surface interaction. Consequently, mixed and boundary regimes of lubrication are prevalent with ubiquitous asperity interactions, leading to increased parasitic losses and poor energy inefficiency. Surface topography has become an important consideration as it influences the prevailing regime of lubrication. As a result a plethora of machining processes and surface finishing techniques have emerged. The stochastic nature of the resulting topography determines the separation at which asperity interactions are initiated and ultimately affect the conjunctional load carrying capacity and operational efficiency. The paper presents a procedure for modelling of asperity interactions of real rough surfaces, from measured data, which do not conform to the usually assumed Gaussian distributions. The model is validated experimentally using a bench top reciprocating sliding test rig. The method demonstrates accurate determination of the onset of mixed regime of lubrication. In this manner, realistic predictions are made for load carrying and frictional performance in real applications where commonly used Gaussian distributions can lead to anomalous predictions.

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A Numerical Solution to the Elasto-Hydrodynamic Problem

Cited by 527 publications

References 3 publications

Big End Bearing Losses with Thermal Cavitation Flow Under Cylinder Deactivation

Big End Bearing Losses with Thermal Cavitation Flow Under Cylinder Deactivation

Two-scale EHL: Three-dimensional topography in tilted-pad bearings

Surface specific asperity model for prediction of friction in boundary and mixed regimes of lubrication

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