Article

Combined influence of couple stress lubricant, recess geometry and method of compensation on the performance of hydrostatic circular thrust pad bearing

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Abstract

This study concerns with the theoretical investigation to show the influence of recess geometry and method of compensation on the performance of recessed hydrostatic circular thrust pad bearing operating with couple stress lubricant. Modified Reynolds equation for couple stress lubricant has been derived using Stokes microcontinuum theory. Stokes theory describes the behavior of fluids consisting of long chain polymer additives having sizes comparable to that of the fluid film thickness. Finite element method technique and commercially available software MATLAB 2013 have been used to solve the modified Reynolds equation and, thus, performance characteristics of bearing have been computed. The performance of capillary- and orifice-compensated hydrostatic thrust pad bearings performance have been compared vis-à-vis to different geometric shapes of recess. Each recess shape has identical ratio of bearing pad area to recess area. It has been observed that the couple stress additives have significant positive influence on the static and dynamic performance of the compensated hydrostatic thrust pad bearing provided that restrictors operates with lower values of the restrictor deign parameter. Limiting values of 10 and 5 for restrictor design parameter have been noticed for capillary and orifice restrictor; beyond these values of , use of couple stress lubricant on the performance of hydrostatic thrust pad bearing become insignificant.

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... Later on, theoretical study from Sinhasan and Jain [3] examined the influence of thrust pad elasticity on the performance of this class of bearing. Recently, Kumar and Sharma [4] examined the influence of recess geometry and compensating element on the performance of hydrostatic thrust pad bearing operating with couple stress lubricant. In order to improve tribological performance of bearing system, base lubricant are often blended with different additives packages. ...
... An iso-viscous and incompressible micropolar lubricant is fed into the recess of hydrostatic thrust pad bearing via orifice restrictor [4]. The modified Reynolds equation for micropolar lubricant is expressed as [8][9][10]: ...
... FEM formulation and Galerkin's approach have been applied on Eq.1 to form global fluid flow domain equation. The global system of equation for hydrostatic thrust pad bearing is expressed as [4,10]: ...
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Commercially available lubricants are often blended with packages of additives to improve their tribological performance. Micropolar fluids are used to describe the behaviour of lubricants blended with additives having microstructure of order of fluid film thickness. These long chain microstructure exhibit motion independent to bulk of the base lubricant. This paper presents a theoretical analysis on the performance of orifice compensated hydrostatic thrust pad bearing system operating with micropolar lubricant. Modified Reynolds equation has been derived using Eringen's micropolar fluid theory. A source code has been developed in MATLAB to solve modified Reynolds equation coupled with restrictor flow equation using Finite Element Method (FEM). Result have been numerically simulated and a comparative study is performed for circular, annular and sectorial multi recess bearing, to provide designer more flexibility in proper selection of recess geometry. Performance characteristics parameters have been evaluated in terms pocket pressure, load carrying capacity, fluid film stiffness and damping coefficient. Irrespective of recess geometry, micropolar lubricant is observed to offer higher load carrying capacity and damping capabilities vis-à-vis to Newtonian lubricant. Furthermore, the gain in aforementioned parameters is observed to be strongly dependent on geometric shape of recess.
... Adding traces of additives in base oil, makes lubricant exhibiting non-Newtonian behavior. Many researcher [6][7][8][9][10] in the past have used different non-Newtonian lubricant model to predict the behaviour of lubricant blended with traces of additives/viscosity improvers. Application of electrically conducting lubricant [10][11][12][13][14][15][16] have received considerable attention for enhancing the performance of this class of bearing. ...
... (2) Steady state (ℎ̅ = 0) performance characteristics i.e. fluid film pressure and load carrying capacity can be obtained by coupled solution equation (2) and capillary restrictor flow equation [9]. Dynamic characteristics i.e. fluid film stiffness ( ̅ = ̅ / ℎ ̅ ) and damping ( ̅ = ̅ / ℎ̅ ) coefficient of the bearing can be evaluated using finite element approach [9]. ...
... (2) Steady state (ℎ̅ = 0) performance characteristics i.e. fluid film pressure and load carrying capacity can be obtained by coupled solution equation (2) and capillary restrictor flow equation [9]. Dynamic characteristics i.e. fluid film stiffness ( ̅ = ̅ / ℎ ̅ ) and damping ( ̅ = ̅ / ℎ̅ ) coefficient of the bearing can be evaluated using finite element approach [9]. ...
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... Later on, theoretical study from Sinhasan and Jain [3] examined the influence of thrust pad elasticity on the performance of this class of bearing. Recently, Kumar and Sharma [4] examined the influence of recess geometry and compensating element on the performance of hydrostatic thrust pad bearing operating with couple stress lubricant. In order to improve tribological performance of bearing system, base lubricant are often blended with different additives packages. ...
... An iso-viscous and incompressible micropolar lubricant is fed into the recess of hydrostatic thrust pad bearing via orifice restrictor [4]. The modified Reynolds equation for micropolar lubricant is expressed as [8][9][10]: Where í µí¼‘(ℎ ̅ , í µí±™ ̅ , í µí±) [10] is micropolar function which depends on non-dimensional fluid film thickness (ℎ ̅ ), characteristics length (í µí±™ ̅ ) and coupling number (í µí±) of micropolar fluids. ...
... FEM formulation and Galerkin's approach have been applied on Eq.1 to form global fluid flow domain equation. The global system of equation for hydrostatic thrust pad bearing is expressed as [4,10]: ...
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This paper theoretically investigates the influence of transverse magnetic field and recess shape on the performance of hydrostatic circular thrust pad bearing. The lubricant is assumed to be electrically conducting in nature. Navier-Stokes equation is modified by adding Lorentz force, so as to describe the flow of electrically conducting lubricant between bearing surfaces. A source code based on FE formulation of modified Reynolds equation is developed to compute the numerically simulated results. The bearing performance is presented in terms of load carrying capacity, fluid film stiffness and damping coefficient as a function of magnetic field (Hartmann number) and recess shape. Annular and elliptical recessed bearing operating with electrically conducting lubricants, are observed to be provide maximum increase in load carrying capacity (43.25%) and damping coefficient (67.7%) respectively.
... Later on, theoretical study from Sinhasan and Jain [3] examined the influence of thrust pad elasticity on the performance of this class of bearing. Recently, Kumar and Sharma [4] examined the influence of recess geometry and compensating element on the performance of hydrostatic thrust pad bearing operating with couple stress lubricant. In order to improve tribological performance of bearing system, base lubricant are often blended with different additives packages. ...
... An iso-viscous and incompressible micropolar lubricant is fed into the recess of hydrostatic thrust pad bearing via orifice restrictor [4]. The modified Reynolds equation for micropolar lubricant is expressed as [8][9][10]: ...
... FEM formulation and Galerkin's approach have been applied on Eq.1 to form global fluid flow domain equation. The global system of equation for hydrostatic thrust pad bearing is expressed as [4,10]: ...
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Commercially available lubricants are often blended with packages of additives to improve their tribological performance. Micropolar fluids are used to describe the behaviour of lubricants blended with additives having microstructure of order of fluid film thickness. These long chain microstructure exhibit motion independent to bulk of the base lubricant. This paper presents a theoretical analysis on the performance of orifice compensated hydrostatic thrust pad bearing system operating with micropolar lubricant. Modified Reynolds equation has been derived using Eringen’s micropolar fluid theory. A source code has been developed in MATLAB to solve modified Reynolds equation coupled with restrictor flow equation using Finite Element Method (FEM). Result have been numerically simulated and a comparative study is performed for circular, annular and sectorial multi recess bearing, to provide designer more flexibility in proper selection of recess geometry. Performance characteristics parameters have been evaluated in terms pocket pressure, load carrying capacity, fluid film stiffness and damping coefficient. Irrespective of recess geometry, micropolar lubricant is observed to offer higher load carrying capacity and damping capabilities vis-à-vis to Newtonian lubricant. Furthermore, the gain in aforementioned parameters is observed to be strongly dependent on geometric shape of recess
... Yadav and Sharma [10] numerically analyzed the influence of the tilt and recess shape on the static and dynamic performance characteristics of the hydrostatic thrust pad bearing system with a Rabinowitsch lubricant, and the tilt had an obvious influence on the bearing performance. Similarly, Kumar and Sharma [11] theoretically investigated the combined influence of couple stress lubricant, recess geometry and method of compensation on the performance of hydrostatic circular thrust pad bearing. Also, the FEA mesh of four-node quadrilateral elements was discretized by ANSYS. ...
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... Since last two decades, theoretical and experimental efforts are made to reduce coefficient of friction and enhance load supporting ability of bearings, by producing micro-features/patterns [9,10] on bearing surface. With these modern manufacturing techniques, many investigations were reported exploring the use of nonconventional pocket shapes such as circular, annular, multipocket [2,11,12] etc. in pads of hydrostatic bearing. These studies reported that use of these non-conventional pocket shapes provide better dynamic characteristics to a hydrostatic bearing. ...
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The effects of couple stresses on the lubrication of rolling contact bearings, including the effects on cavitation, were studied by defining a parameter l which has dimensions of length. It was found that, the larger the chain length of the lubricant or additive molecule, the greater are the effects due to couple stresses. The presence of couple stresses produces an increase in the load capacity. However, cavitation is accelerated.
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This paper presents a theoretical study of the performance characteristics of hydrostatic rigid orifice compensated multirecess journal bearings using non-Newtonian lubricants. The generalized Reynolds equation governing the flow of lubricant having variable viscosity has been solved using the finite element method and iterative procedure. The static and dynamic performance characteristics are presented for non-Newtonian lubricants of which constitutive equation has been represented by the cubic shear stress law. The non-linearity factor () in the cubic shear stress law significantly influences the bearing performance characteristics, particularly the dynamic characteristics.
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The effects of the interaction between the restrictor design parameter (), the deformation coefficient () and the Poissons ratio (ν), on the performance characteristics of an orifice-compensated hydrostatic circular thrust pad bearing have been studied. The results are presented for various values of and are compared with those of capillary-compensated bearings
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This work presents an experimental study to assess the performance characteristics of hydrostatic thrust bearings. A test rig is designed for testing two configurations of hydrostatic bearings compensated by a capillary tube, one with a mid-circular recess and the other with multi-sectors (four recesses of different recess radii ratios). The performance characteristics have been measured, namely, oil film thickness, recess pressure, pressure distribution and oil flow rate. A specially devised computer program using an iterative technique has been adopted to compute numerically the pressure distribution and predict other performance characteristics. Good agreement has been obtained between predicted theoretical performance and that experimentally measured. The results demonstrate that the bearing recess size and location have a great influence on the performance of the hydrostatic thrust bearing.
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Assuming the lubricant to be an incompressible fluid with couple stress, a theoretical study is made of squeeze films between two infinitely long rectangular plates, between two circular plates and in a thrust bearing. Fluids with couple stress are better lubricants than Newtonian fluids. The load capacity of a thrust bearing can be increased and the squeeze in the squeeze film can be decreased by the use of a fluid with couple stress as the lubricant.
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A comprehensive review of the existing theories of microcontinuum fluid mechanics has been presented by the authors in a previous paper. In this paper the published applications of these microfluid theories to real and ideal flow problems have been reviewed briefly and these short reviews are presented in tabular form for easy reference.RésuméUne revue étendue des théories existantes de la mécanique des milieux microcontinus fluides a été présentée par les auteurs dans un précédent article. Dans cet article les applications publiées de ces théories des microfluides à des problèmes d'écoulement eédls st parfaits ont étt́é rapidement passés en revue et ces brèves revues sont présentées sous forme tabulaire afin de s'y référer facilement.ZusammenfassungIn einer früheren arbeit gaben die autoren eine umfassende Übersicht über die bestehenden Theorien der Mikrokontinuum-Flüssigkeitsmechanik. In dieser Arbeit werden die veröffentlichten anwendungen dieser Mikroflüssigkeitstheorien auf wirkliche und ideale Stromprobleme kurz besprochen und diese kurzen Besprechungen werden für leichte Bezungsnahme in Tabellenform vorgelegt.SumàrioUna recensione completa delle esistenti teorie sulla meccanica dei fluidi microcontinui è stata presentata dagli autori in una loro precedente pubblicazione. In questo articolo bengono passate brevemente in ressegna le applicazioni già pubblicate di queste teorie sui microfluidi ai problemi del flusso reale e ideale; queste brevi recensioni vergono presentate in forma tabellare per facilitare i riferimenti.РефератB пpчдыдuщчй paбoтч aBтopoB дaн пoлный oбзop cuщчcтBuющич тчopий мччaники жидкocтчй микpoкoнтинuuмa.B этoй paбoтч дaчтcя кpaткий oбзop изBчcтныч пpимчнчний B литчpaтupч этич тчopий микpoжидкocтчй к пpoблчмaм pчaльнoгo н идчaльнoгo пoтoкa. Для лчгкocти cпpaBки пpчдcтaBлчны эти кpaткич oбзopы B тaбличнoй фopмч.
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Libro de aplicación de la tribología, ciencia interdisciplinaria que conjuga toda una serie de elementos importantes en el diseño, fabricación y operación de las máquinas como la fricción, naturaleza de los materiales, rugosidad, desgaste, lubricación, consumo de energía y medio ambiente. Contenido: Tribología-fricción, desgaste y lubricación; Lubricantes y lubricación; Textura de la superficie; Materiales de rodamiento; Fundamentos de flujo viscoso; Ecuación de Reynolds y sus aplicaciones; Cojinetes de empuje; Cojinete liso (chumacera); Lubricación de cojinetes; Cojinetes hidrostáticos; Cojinetes de aire; Cojinetes secos y carentes de lubricación; Prototipos y tamaños de selección de cojinetes; Principios y límites de operación; Fricción, desgaste y lubricación.
A parametric investigation on the microelastohydrodynamic lubrication of power law fluid lubricated line contact
  • G D Thakre
  • Sharma
  • Sc
  • S P Harsha