Hydrodynamic lubrication with deterministic micro textures considering fluid inertia effect

Ismail, Syed; Sarangi, Mihir

doi:10.1016/j.triboint.2013.08.011

Cited by 35 publications

(28 citation statements)

References 23 publications

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“…In line with the laminar results [18], the present analysis also shows higher load support in positive textures due to intensive hydrodynamic effect around the textures as compared to negative textures. The pressure developed in the positive textured surface is higher as compared to negative textured surface as observed in Fig.…”

Section: Theorysupporting

confidence: 91%

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Influence of surface textures on the hydrodynamic performance of parallel sliding contacts in turbulent regime

Ismail

Sarangi

2019

J Braz. Soc. Mech. Sci. Eng.

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Generally, turbulent flow in bearings occurs mainly due to two reasons: high operational speed and use of unconventional lubricants. The present work is focused to investigate the effects of both positive and negative textures in terms of texture shape, size, height, orientation and number of textures in transverse direction, on the hydrodynamic performance of parallel sliding contacts in turbulent regime. Ng and Pan model is used to incorporate turbulent flow condition in pressure governing equation. It has been noticed that Reynolds number, texture shape, size and height play significant role in enhancing the lubrication performance. In turbulent flow, friction parameter shows higher magnitude as compared to laminar flow which is undesirable. Keywords Negative textures • Parallel sliding contacts • Positive textures • Turbulent flow List of symbols C Maximum clearance between the surfaces F Friction force h Film thickness of the lubricant h g Height of the protrusion l Base length of surface texture k x and k z Frictional flow rate parameters in the x-and z-directions L X Length of the unit cell in x-direction L Z Length of the unit cell in z-direction N x , N z Mesh size in x-and z-directions, respectively p Pressure in the lubricant film Q End flow in z-direction Re Reynolds number (UL x) U Sliding velocity in x-direction w Load support Dynamic viscosity of the lubricant Density of the lubricant Non-dimensional parameters a Aspect ratio (area of textured surface/area of unit cell) F Friction force FC∕ UL X L Z h Film thickness (h∕ C) H Texture height ratio h g C k Ratio of the imaginary cell lengths (L X ∕ L Z) K ax , K az Apparent height of film thickness K ax =h k 1∕ 3 x , K az =h k 1∕ 3 z p Pressure pC 2 UL X Q End flow Q∕ UCL X w Load support WC 2 UL 2 X L Z x x-coordinate x∕L X ȳ y-coordinate (y∕C) z z-coordinate z∕L Z (L X ∕ C) Friction parameter

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Section: Theorysupporting

confidence: 91%

“…Surface textures are assumed to be provided on the stationary surface of parallel sliding contacts, and unit square cell is considered on the stationary surface in such a way that each texture should be at centre of the cell with sides L X = L Z , as reported in [18] and also shown in Fig. 1.…”

Section: Theorymentioning

confidence: 99%

Influence of surface textures on the hydrodynamic performance of parallel sliding contacts in turbulent regime

Ismail

Sarangi

2019

J Braz. Soc. Mech. Sci. Eng.

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“…Several studies reported that the inertia significantly affects bearing performance both theoretically [1][2][3][4][5][6][7] and numerically [8][9][10]. Based on analytical approach, Safar and Shawki [1] investigated the effect of inertia force on the turbulent bearing characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…However, in squeeze film air contact, the results indicated that fluid inertia does not significantly affect the load-carrying capacity of the contact [4]. Syed and Sarangi [8] examined the lubricating performance of textured parallel sliding contacts considering fluid inertia effect. The results indicated that fluid inertia effect leads to changes in the performance parameters.…”

Section: Introductionmentioning

confidence: 99%

Effect of inertia on the cavitation phenomena of hydrodynamic textured bearings considering slip

Jamari

Muchammad

Hilmy

et al. 2019

J Braz. Soc. Mech. Sci. Eng.

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Surface modification of a lubricated bearing, such as hydrophobic coating inducing slip situation and texturing, is proved to enhance hydrodynamic performance. As widely known, in textured surface lubricant inertia and cavitation can significantly affect the hydrodynamic pressure profile. However, a brief literature review indicates that studies related to the correlation between cavitation and inertia, especially in the presence of slip, are considerably limited. The present study examines the effect of inertia on cavitation phenomena by considering the slip boundary using two approaches, namely computational fluid dynamics based on full Navier-Stokes equations and analytical lubrication equation based on the Reynolds equation. The modified Reynolds equation with slip concept is used with respect to the slip effect applied on the surface of the bearing. The results indicate that the inertia as well as the slip condition significantly affects the cavitation area. It is also highlighted that the cavitation area reduces by increasing the inertia effect, and it becomes smaller when the slip is introduced.

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“…The oil film is extremely thin, and under mixed or boundary lubrication, more oil film bursts and changes to a dry friction condition [12]. The lubrication and friction state of a textured surface is influenced by various effects, which means that the mechanism is very complex and difficult to study [13][14][15][16]. At present, experimental research on the friction property of surface texture is mainly focused on the full oil condition, which is generally only applicable to simulation of the position near the middle of the piston stroke [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Influence of Surface Texture Parameters on Friction Characteristics Under Starved Lubrication

Zhang

Wei

et al. 2020

Polish Maritime Research

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A cylinder liner and piston ring running under starved lubrication near the top dead centre (TDC) and bottom dead centre (BDC) cause abnormal friction and wear during operation of a marine diesel engine. The method of laser texturing is proposed to improve the surface friction property under this condition. Spherical crown pits with different parameters were formed on the surface of samples by femtosecond laser processing. The BDC and TDC conditions of oil starvation were simulated in a reciprocating friction and wear experiment, and a numerical model of surface texture lubrication based on the Reynolds equation was established. The influence of the distribution density, diameter, and depth parameters of the texture on the surface properties was studied. In the BDC condition, compared with the untextured surface, the average coefficient of friction (COF) can be reduced by up to 24% and the average friction force can be reduced by up to 18%. In the TDC condition, the COF can be reduced by up to 19%, and the average friction force can be reduced by up to 18%. Therefore, the textures with various parameters should be arranged in different positions on the cylinder liner; more attention should be paid to the optimisation of diameter in the texture of the cylinder liner near the BDC, whereas more attention should be paid to the optimisation of distribution density in the texture of the cylinder liner near the TDC

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Hydrodynamic lubrication with deterministic micro textures considering fluid inertia effect

Cited by 35 publications

References 23 publications

Influence of surface textures on the hydrodynamic performance of parallel sliding contacts in turbulent regime

Influence of surface textures on the hydrodynamic performance of parallel sliding contacts in turbulent regime

Effect of inertia on the cavitation phenomena of hydrodynamic textured bearings considering slip

Influence of Surface Texture Parameters on Friction Characteristics Under Starved Lubrication

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