The aim of this paper was to understand the parameters influencing grease film thickness in a rolling elastohydrodynamically lubricated contact under fully flooded conditions at medium speeds. Film measurements were taken pure for six commercial greases and their bled oils. found be higher than corresponding oil, suggesting presence thickener contact. No rheological properties (characterized by steady dynamic shear) showed any direct relation studied greases. AFM microstructure, from which...

This paper investigates the influence of a transverse ridge on film thickness in circular EHL contact under rolling/sliding conditions. It is numerical simulation optical work Kaneta et al. (1992). One purposes this investigation to check validity algorithm and Newtonian, isothermal lubricant assumption for predictions these conditions (ph = 0.54 GPa). will be shown that, both quantitatively, central axis Y 0, qualitatively, profile through “pseudo interference graphs”, agreement between...

This paper focuses on the lubrication behavior of starved elliptical Elasto-HydroDynamic (EHD) contacts. Starvation is governed by amount lubricant available in inlet region and can result much thinner films than occurring under fully flooded conditions. Therefore, it would be desirable to able predict onset severity starvation relate film reduction directly operating conditions properties. The aim this work explore influence these parameters starvation. A combined modeling experimental...

ver since the start of aviation, birds and airplanes have posed a mutual risk: Birds are killed when struck by aircraft, but, in return, bird strikes cause billions damage to aviation industry.Airports employ bird-control methods such as audiovisual deterrents (like scarecrows, lasers, noise), weapons, chemicals relocate, suffocate, or otherwise terminate [2].While latter work, they ethically questionable.The problem is that quickly lose effectiveness due habituation.The approach works...

Lubrication flows appear in many applications engineering, biophysics and nature. Separation of surfaces minimisation friction wear is achieved when the lubricating fluid builds up a lift force. In this paper we analyse soft lubricated contacts by treating solid walls as viscoelastic: materials are typically not purely elastic, but dissipate energy under dynamical loading conditions. We present method for viscoelastic lubrication focus on three canonical examples, namely Kelvin–Voigt,...

This paper investigates in detail the influence of two different surface topographies on pressure distribution and film thickness profile a highly loaded (maximum Hertzian 2 GPa) line contact as function slide to roll ratio. To accomplish this transient Reynolds equation is solved both space time. The first feature under investigation localized, so-called indentation, second one global: waviness. observed lack synchronism extremes explained theoretically by analyzing equation. minimum...

Abstract Surface roughness and/or surface imperfections are well known to significantly affect the performance of concentrated contacts. Any deviation from smooth will act as a stress raiser for itself (bump) or its neighborhood (dent), and therefore reduce fatigue life component it is part of. These can also initiation sites other types contact failure such scuffing, when conditions load, speed film thickness become more severe. With help increasing computer speeds efficient numerical...

This article traces the contribution of Dowson and Higginson work to numerical line contact elasto-hydrodynamic lubricated film thickness prediction Hamrock in elliptical contacts. Considering work, this shows that both pressure results curve-fitted predictions are very accurate, even by today's standards. Concerning results, authors show original remain surprisingly accurate but issue minimum central thicknesss ration H m / c is not yet completely settled. The then continues discuss some...

We consider a heavily loaded, lubricated contact between two elastic bodies at relative speed U, such that there is substantial deformation. As result of the interplay hydrodynamics and non-local elasticity, fluid film develops solids, whose thickness scales as U3/5. The profile h selected by universal similarity solution along upstream inlet. Another valid outlet, which exhibits local minimum in thickness. solutions are connected hyperbolic problem underneath contact. Our asymptotic results...

Abstract

Fast-turn around methods to predict airfoil trailing-edge noise are crucial for incorporating limitations into design optimization loops of several applications. Among these aeroacoustic predictive models, Amiet's theory offers the best balance between accuracy and simplicity. The model relies heavily on precise wall-pressure spectrum predictions, which often based single-equation formulations with adjustable parameters. These parameters calibrated particular airfoils flow conditions...

Power minimisation in branched fluidic networks has gained significant attention biology and engineering. The optimal network is defined by channel radii that minimise the sum of viscous dissipation volumetric energetic cost fluid. For limit cases including laminar flows, high Reynolds number turbulence, or smooth approximations, solutions are known. However, no single optimisation approach captures these cases. Furthermore, realistic exhibit intermediate points parameter space can hardly be...

Surface roughness effects in line and point elastohydrodynamically lubricated contacts are compared it is shown that the underlying behaviours both types of contact identical. Long wavelength components attenuated; short pass through conjunction unaltered. It also attenuation, plotted against a non-dimensional wavelength, follows almost identical curves cases.

In this paper the influence of surface roughness on pressure profile and film thickness in a steady state EHL line contact is investigated using input from an actually measured calculations. Pressure profiles shapes for different load conditions are shown. The presented results strongly indicate that situation considered here significant deformation occurs. As result often used λ parameter being ratio standard deviation (h/σ) with σ based undeformed may give misleading information as far...

The application of multilevel multi-integration to the calculation elastic deformation integrals and use an alternative relaxation process in solution governing equations have resulted algorithm solving EHL line contact problem O(n ln n) operations, also for highly loaded situations. reduction computing time thus obtained was used solve using large numbers nodal points study pressure spike. presented will enable fast accurate surface roughness transient problems.

Abstract Microcapsules with a liquid core and solid shell composed of hydrophobic nanoparticles are broadly applied in food, pharmaceutics, biotechnologies. For example, Pickering emulsions, colloidosomes, or antibubbles (droplets surrounded by air layers water) enable controlled release active agents, biocompatibility, contact‐less transportation. However, producing nanoparticle‐ polymer‐laden shells at scale is highly challenging, since bulk methods polydisperse microfluidic chips prone to...

The detailed understanding of elastohydrodynamic lubrication (EHL) with rough surfaces has become an important problem as the ratio film thickness to surface roughness is decreasing. Recently it been recognized that inside EHL contact might be different from outside owing elastic deformation. As will explained in this paper, a first step deformation real knowledge amplitude reduction harmonic features, which forms topic paper. For line shown deformed feature (waviness) depends on original...

In this paper a Multigrid extension of stationary solver is outlined for the EHL solution line contact under transient conditions. The applied to calculate pressure and film thickness profiles at each time step when an indentation moving through contact, which results in asymmetric profile. time-dependent are compared with solutions. as function presented well integrated (over time) spatial coordinate. These pressures used compute sub-surface stress field, shows higher stresses below...

The prediction of bearing life and performance requires detailed knowledge the behaviour elasto-hydrodynamically lubricated (EHL) contacts under varying conditions load lubricant supply during many cycles. Considering starved lubrication, a model is developed that predicts change layer to EHL contact. As film thickness inside contact determined by distribution layer, this can be used predict decay. A formula for central decay obtained long-term operation circular or elliptical conditions....

Turbulence distortion due to airfoil finite thickness is an important but not fully understood phenomenon that affects the radiated noise, resulting in inaccurate noise predictions. This study discusses turbulence leading edge (LE) region of aiming obtain more accurate LE Wind tunnel experiments were performed for National Advisory Committee Aeronautics (NACA) 0008 and NACA 0012 airfoils at zero angle attack subjected large length scales (between 10 43 times radius) generated by a grid rod....