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

  • Ismail SyedEmail author
  • M. Sarangi
Technical Paper
  • 14 Downloads

Abstract

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 (\({{\rho UL_{x} } \mathord{\left/ {\vphantom {{\rho UL_{x} } \eta }} \right. \kern-0pt} \eta }\))

U

Sliding velocity in x-direction

w

Load support

\(\eta\)

Dynamic viscosity of the lubricant

\(\rho\)

Density of the lubricant

Non-dimensional parameters

\({\bar{\text{a}}}\)

Aspect ratio (area of textured surface/area of unit cell)

\(\bar{F}\)

Friction force \(\left( {{{FC} \mathord{\left/ {\vphantom {{FC} {\eta UL_{X} L_{Z} }}} \right. \kern-0pt} {\eta UL_{X} L_{Z} }}} \right)\)

\(\bar{h}\)

Film thickness \(\left( {{h \mathord{\left/ {\vphantom {h C}} \right. \kern-0pt} C}} \right)\)

\(\bar{H}\)

Texture height ratio \(\left( {{{h_{g} } \mathord{\left/ {\vphantom {{h_{g} } C}} \right. \kern-0pt} C}} \right)\)

\(k\)

Ratio of the imaginary cell lengths (\({{L_{X} } \mathord{\left/ {\vphantom {{L_{X} } {L_{Z} }}} \right. \kern-0pt} {L_{Z} }}\))

\(K_{ax} ,K_{az}\)

Apparent height of film thickness \(\left( {K_{ax} = {\raise0.7ex\hbox{${\bar{h}}$} \!\mathord{\left/ {\vphantom {{\bar{h}} {k_{x}^{{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-0pt} 3}}} }}}\right.\kern-0pt} \!\lower0.7ex\hbox{${k_{x}^{{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-0pt} 3}}} }$}},K_{az} = {\raise0.7ex\hbox{${\bar{h}}$} \!\mathord{\left/ {\vphantom {{\bar{h}} {k_{z}^{{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-0pt} 3}}} }}}\right.\kern-0pt} \!\lower0.7ex\hbox{${k_{z}^{{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-0pt} 3}}} }$}}} \right)\)

\(\bar{p}\)

Pressure \(\left( {{{pC^{2} } \mathord{\left/ {\vphantom {{pC^{2} } {\eta UL_{X} }}} \right. \kern-0pt} {\eta UL_{X} }}} \right)\)

\(\bar{Q}\)

End flow \(\left( {{Q \mathord{\left/ {\vphantom {Q {UCL_{X} }}} \right. \kern-0pt} {UCL_{X} }}} \right)\)

\({\bar{\text{w}}}\)

Load support \(\left( {{{WC^{2} } \mathord{\left/ {\vphantom {{WC^{2} } {\eta UL^{2}_{X} L_{Z} }}} \right. \kern-0pt} {\eta UL^{2}_{X} L_{Z} }}} \right)\)

\(\bar{x}\,\)

x-coordinate \(\left( {x/L_{X} } \right)\)

\(\bar{y}\)

y-coordinate \(\left( {y/C} \right)\)

\(\bar{z}\)

z-coordinate \(\left( {z/L_{Z} } \right)\)

\(\mu ({{L_{X} } \mathord{\left/ {\vphantom {{L_{X} } C}} \right. \kern-0pt} C})\)

Friction parameter

Notes

Acknowledgements

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Compliance with ethical standards

Conflict of interest

The author(s) declare(s) that there is no conflict of interest.

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Copyright information

© The Brazilian Society of Mechanical Sciences and Engineering 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringNational Institute of Technology WarangalWarangalIndia
  2. 2.Department of Mechanical EngineeringIndian Institute of Technology KharagpurKharagpurIndia

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