Performance Of Squeeze Film Research Articles

An Effect of a Porous Structure, Slip Velocity and Rosensweig’s Viscosity on the Ferrofluid Based Squeeze Film in Porous Curved Annular Plates

An endeavor has been made to analyze porous squeeze film performance in curved annular plates considering slip velocity, Kozeny-Carman’s porous structure and Rosensweig’s viscosity in Shliomis model-based magnetic fluid lubrication. The globular sphere model of Kozeny-Carman for porous facing is adopted here. An extension of the Einstein’s viscosity for ferrofluid proposed by Rosensweig is considered here to improve the viscosity of ferrofluid for the Shliomis model, while Beavers and Joseph’s slip model is used for evaluating the slip effect. The pressure and load lifting capacity in dimensionless form is obtained by modifying the Reynolds equation incorporating the Rosensweig’s viscosity, Kozeny-Carman’s model-based porosity, slip and Shliomis model-based ferofluid lubrication. The graphical representation reveals that load carrying capacity (LCC) can be increased by increasing the curvature of upper plates, volume concentration and magnetization parameter but decrease with the slip velocity, porous structure parameter and porosity parameter. This study indicates that the load-bearing capacity remains higher as compared to the case of Einstein’s viscosity model. However, this investigation conclusively establishes that the Shliomis model goes ahead of the other two magnetic fluid flow models in overall improvement of bearing performance characteristics. Interestingly, even considerable amount of slip may not pose a serious problem when Kozeny-Carman’s model is resorted to. This investigation reveals that this type of bearing system sustains good amount of load even in the absence of flow which does not happen in the case of conventional bearing system.

Effects of both cavitation and non-Newtonian behavior on the performance of oscillatory anisotropic poroelastic squeeze film

PurposeThe purpose of this study is to present a theoretical investigation of the effects of cavitation and couple stress on the squeeze film behavior between an anisotropic poroelastic rigid disc and a sinusoidally oscillating rigid disc.Design/methodology/approachBased on the microcontinuum theory of Vijay Kumar Stokes and the Elrod–Adam algorithm, the non-Newtonian Reynolds equation coupled with modified Darcy's law for lubricant flow through the porous disc is derived. This numerical study includes the continuity of tangential velocity at the porous–fluid interface and the effects of percolation of the polar additives into the anisotropic porous disc.FindingsThe effects of couple stress, oscillating amplitude, percolation additives, permeability and anisotropic permeability on the squeeze film characteristics are discussed. It is found that both the percolation effect of the lubricant additives and the anisotropic structure of the porous surface reduce the flow in the porous disc, resulting in a decrease in pressure. It is also observed that cavitation effects are more pronounced for Newtonian fluids than couple stress fluids.Originality/valueThe results of this study can be used to design a variety of engineering applications such as bearings, wet clutches and non-contact mechanical seals.

The Performance of Squeeze Film between Parallel Triangular Plates with a Ferro-Fluid Couple Stress Lubricant

The present study aims at investigating a couple stress ferrofluid lubricant effects on the performance of the squeezed film when a uniform external magnetic field is applied. For this purpose, Shliomis ferrohydrodynamic and couple stress fluid models are employed. The considered geometry is parallel triangular plates. The effects of couple stress, volume concentration, and Langevin parameters on squeeze film characteristics including time vs. height relationship and load-carrying capacity are investigated. According to the results, employing couple stress ferrofluid lubricant in the presence of the magnetic field leads to an increased performance of the squeeze film.

Effects of piezo-viscous–coupled stress lubricant on the squeeze film performance of parallel triangular plates

The paper shows the combined effects of couple stress fluids and lubricant viscosity variation with pressure in squeeze film performance of parallel triangular plates. By solving Reynolds equation and using perturbation method, the pressure distribution is obtained with consideration of viscosity variation with pressure. Also, with integrating pressure in the film region, load-carrying capacity is derived. A fourth-order Rang–Kutta is used to solve the nonlinear differential equation between lubricant film thickness and time. Various cases of couple stress, iso-viscous and piezo-viscous contributions are analyzed. According to the results, it is found that using couple stress fluid as a lubricant and considering viscosity–pressure dependency will increase characteristics of the squeeze film such as load-carrying capacity, pressure distribution, and triangular plates moving time, significantly as compared to the classical Newtonian iso-viscous lubricant.

Performance of hydromagnetic squeeze film in longitudinally rough conducting truncated conical plates

Performance of hydromagnetic squeeze film in longitudinally rough conducting truncated conical plates

A Study of Hydromagnetic Longitudinal Rough Circular Step Bearing

This article discusses the effect of longitudinal roughness on the performance of hydromagnetic squeeze film in circular step bearing. To characterize the random roughness of the bearing surfaces the stochastic model of Christensen and Tonder has been employed. The stochastically averaged Reynolds’ type equation is solved using suitable boundary conditions to obtain the pressure distribution and then the load bearing capacity is computed. The results are presented in graphical form. The graphical results presented here establish that the hydromagnetic lubrication offers significant help to the longitudinal roughness pattern to enhance the performance of the bearing system. Of course, conductivities of the plates, standard deviation, and the supply pressure contribute towards reducing the negative effect induced by variance (+ve) and skewness (+ve).

Investigation of squeeze film performance in rough parallel circular discs by ferro-fluid couple stress lubricant considering effects of rotational inertia

PurposeThe purpose of this paper is to investigate squeezing and rotating motions between two rough parallel circular discs lubricated by ferro-fluid couple stress lubricant.Design/methodology/approachBased upon the Stokes couple stress theory, ferro-hydrodynamic model of Shliomis and Christensen rough surfaces model, squeeze-film characteristics between two rough parallel circular discs considering rotational inertia effects are obtained.FindingsAccording to the results, it is found that the combined effects of couple stresses and ferro-fluid lubricants increases squeeze film performance with respect to the classical Newtonian lubricant. However, increasing the rotational inertia parameter reduces squeeze film characteristics. On the other hand, depending on the structure of surface roughness, the squeeze film characteristics can be increased or decreased. Furthermore, results show that the surface roughness with circular pattern increases squeeze film characteristics, while the surface roughness with radial pattern will decrease it.Originality/valueThis paper is relatively original and describes the squeeze film characteristics between two parallel circular discs with ferro- fluid, rotational inertia, couple stresses and surface roughness effects.

Static and dynamic characteristics of an orifice compensated three-pad hydrostatic squeeze film damper

PurposeThe purpose of this study is to examine the dynamic performance of an orifice-compensated three-pad hydrostatic squeeze film damper.Design/methodology/approachA numerical model has been developed and presented to study the effect of eccentricity ratio and pressure ratio on the static and dynamic characteristics of an orifice-compensated three-pad hydrostatic squeeze film damper. It is assumed that the fluid flow is incompressible, laminar, isothermal and steady-state. The finite difference method has been used to solve Reynolds equation governing the lubricant flow in film thickness of hydrostatic bearing. The numerical results obtained are discussed, analyzed and compared between three- and four-lobe hydrostatic journal bearings available in the literature.FindingsIt was found that the influence of eccentricity ratio on dynamic characteristics of an orifice-compensated three-pad hydrostatic squeeze film damper appears to be essentially controlled by the concentric pressure ratio. It was also found that the three-pad hydrostatic squeeze film damper has higher stiffness than three and four-lobe hydrostatic journal bearings.Originality/valueIn fact, the results obtained show that this type of hydrostatic squeeze film damper provides hydrostatic designers a new bearing configuration suitable to control rotor vibrations.

Pressure distribution with surface roughness for effect between porous infinitely long rectangular plates with MHD couple stress squeeze film lubrication

This investigation is an analysis of MHD couple stress squeeze film performance with a rough surface between porous infinitely long rectangular plates. The pressure equation for the magnetic field is mathematically derived using Christensen’s stochastic equation. Therefore, the upshot of this magnetic effect reveals the enhanced performance of the pressure which is compared to the Newtonian instance.

Squeeze film performance of parallel annular plates by ferrofluid couple stress lubricant considering effects of rotational inertia

PurposeThe purpose of this paper is to investigate squeezing and rotating motions between two parallel annular discs lubricated by ferro-fluid couple stress lubricant in the presence of a uniform magnetic field.Design/methodology/approachBased upon the Stokes couple stress theory and ferro-hydrodynamic model of Shliomis, squeeze film characteristics between two parallel annular discs are obtained.FindingsAccording to the results, it is found that the combined effects of couple stress and ferro-fluid lubricant increase squeeze film performance with respect to the classical Newtonian lubricant. However, an increase in the rotational inertia parameter reduces squeeze film characteristics.Originality/valueThis paper is relatively original and describes the squeeze film characteristics between two parallel annular discs with rotational inertia, couple stress and ferro-fluid lubricant effects.

Derivation of Non-Newtonian Magnetic Fluid Lubricated Rough Centrosymmetric Squeeze Film Reynolds Equation and its Application

AbstractBased upon the Shliomis ferromagnetic fluid model and the Stokes microcontinuum theory incorporating with the Christensen stochastic model, a modified Reynolds equation of centrosymmetric squeeze films has been derived in this paper. The Reynolds equation includes the combined effects of non-Newtonian rheology, magnetic fluids with applied magnetic fields, rotational inertia forces, and surface roughness. To guide the use of the derived equation, the squeeze film of rotational rough-surface circular disks lubricated with non-Newtonian magnetic fluids is illustrated. According to the results obtained, the effects of rotation inertia decrease the load capacity and the squeeze film time of smooth circular disks. By the use of non-Newtonian magnetic fluids with applied magnetic fields, the rotational circular disks predict better squeeze film performances. When the influences of circumferential roughness patterns are considered, the non-Newtonian magnetic-fluid lubricated rotational rough disks with applied magnetic fields provide further higher values of the load capacity and the squeeze film time as compared to those of the smooth case.

Investigation of couple stress effects on poroelastic squeeze film of parallel plates

AbstractThe couple stress effects on hydrodynamic performances of poroelastic squeeze film in the case of infinitely long parallel plates are examined in this paper. The lower plate is a poroelastic matrix saturated by a Newtonian fluid. The poroelasticity is taken into account by the means of homogenisation method. The rheological behaviour of the lubricant is described by the Stokes couple stress fluid theory. The modified Reynolds equation accounting for the couple stress, the elasticity of the poroelastic plate and the slip velocity condition at the film–poroelastic plate interface is derived. The governing equations in the fluid film and poroelastic plate are discretised by finite difference method and solved iteratively by using Gauss–Seidel method. The fluid film and poroelastic plate coupling is managed by the iterative fixed point technique. A computer program is developed in this study. The result analysis shows that couple stress effects on poroelastic squeeze film performances are significant. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of fluid inertia forces in ferrofluid lubricated circular stepped squeeze films – Shliomis model

Purpose This paper aims to study the inertia squeeze film characteristics between ferrofluid-lubricated circular stepped disks. Owing to the development of modern machine systems, the application of ferrofluids has received great attention. Because the circular disks are a special situation of circular stepped squeeze films, a further study of fluid inertia force effects on the ferrofluid-lubricated circular stepped squeezing mechanism is motivated. Design/methodology/approach On the basis of the ferrohydrodynamic flow model of Shliomis incorporating the momentum integral method, the effects of fluid inertia forces in ferrofluid-lubricated circular stepped squeeze films in the presence of external magnetic fields are investigated in this study. Analytical solutions of squeeze film performances are derived. Findings The fluid inertia force effects provide an increased load capacity and a longer squeeze film time for the ferrofluid-lubricated circular stepped squeeze film, especially for a larger value of the inertia parameter, the Langevin parameter and the volume concentration and a smaller value of the radius ratio and the step height ratio. Originality/value For engineering applications, numerical tables for squeeze film loads of circular stepped disks are also provided in this paper.

Combined effects of piezo – viscous coupled stress lubricant and rotational inertia upon squeeze film performance of rough circular discs

Purpose – The purpose of this paper is to investigate squeezing and rotating motions between two rough parallel circular discs lubricated by piezo – viscous couple stress lubricant with pressure-dependent viscosity variation. Design/methodology/approach – Based upon the Stokes couple stress theory, Barus viscosity-pressure dependency relation and Christensen rough surfaces model, squeeze film characteristics between two rough parallel circular discs are obtained. Findings – According to the results, it is found that, the combined effects of couple stresses and viscosity-pressure dependency increases squeeze film performance with respect to the classical Newtonian iso-viscous (constant viscosity) lubricant. However, increasing the rotational inertia parameter reduces squeeze film characteristics. On the other hand, depending on the structure of surface roughness, the squeeze film characteristics can be increased or decreased. Furthermore, results show that the surface roughness with circular pattern increases squeeze film characteristics, while the surface roughness with radial pattern will decrease it. Originality/value – This paper is relatively original and describes the squeeze film characteristics between two parallel circular discs with viscosity-pressure dependency, rotational inertia, couple stresses and surface roughness effects.

Effects of circumferential and radial rough surfaces in a non-Newtonian magnetic fluid lubricated squeeze film

The effects of surface roughness in circular squeeze film disks lubricated with a non-Newtonian magnetic fluid are investigated in this paper. Employing the stochastic model together with the microcontinuum theory and the ferromagnetic flow model, a non-Newtonian magnetic-fluid lubricated Reynolds equation including the influences of rough surfaces is derived, and applied to predict the squeeze film performances. According to the results, the surface roughness effects of circumferential structures increase the mean load capacity and lengthen the mean approaching time as compared to those of the smooth disks with a non-Newtonian magnetic fluid. However, the radial roughness patterns yield a reversed trend. In addition, the effects of rough surfaces on the squeeze film characteristics are more pronounced for circular disks operating with larger values of the surface roughness parameter, the non-Newtonian couple stress parameter, the volume concentration parameter and the magnetic Langevin parameter.

MAGNETO-HYDRODYNAMIC NON-NEWTONIAN CURVED CIRCULAR SQUEEZE FILMS

The squeeze film performances between curved circular plates lubricated with an electrically conducting non-Newtonian fluid in the presence of external magnetic fields are investigated in this paper. Based upon the magneto-hydrodynamic flow theory together with the Stokes microcontinuum theory, the magneto-hydrodynamic non-Newtonian Reynolds equation is derived and applied to predict the curved circular squeeze film behaviors. Comparing with the hydrodynamic Newtonian case, the squeeze film characteristics for curved circular plates are improved by the use of an electrically conducting non-Newtonian fluid in the presence of external magnetic fields. Numerical values of the load capacity and the approaching time are provided in Tables for engineering applications.

Squeeze film performance in rough porous infinitely long parallel plates with porous matrix of variable film thickness under the presence of a magnetic fluid lubricant

Squeeze film performance in rough porous infinitely long parallel plates with porous matrix of variable film thickness under the presence of a magnetic fluid lubricant

Shliomis model-based magnetic squeeze film in rotating rough curved circular plates: a comparison of two different porous structures

This study aims to analyse the effect of different porous structures on the performance of a Shliomis model-based magnetic squeeze film in rotating rough porous curved circular plates. For porous structures Kozeny-Carman’s formulation and Irmay’s model have been adopted. A Shliomis model-based magnetic fluid flow is considered. The stochastically averaging models of Christensen and Tonder have been used for characterising the effect of transverse roughness. The associated stochastically averaged Reynolds type equation is solved to obtain the pressure distribution leading to the calculation of the load carrying capacity. The results presented in graphical form show that the adverse effect of transverse roughness can be compensated by the positive effect of magnetisation in the case of negatively skewed roughness, suitably choosing the rotation ratio and the curvature parameters. Further, this compensation appears to be more in the case of Kozeny-Carman’s formulation as compared to that of Irmay’s model, which makes the Kozeny-Carman’s model a superior choice.

A Study on the Performance of Hydromagnetic Squeeze Film between Anisotropic Porous Rectangular Plates with Couplestress Fluids

A Study on the Performance of Hydromagnetic Squeeze Film between Anisotropic Porous Rectangular Plates with Couplestress Fluids

Effects of non‐Newtonian Rabinowitsch fluids in wide parallel rectangular squeeze‐film plates

PurposeIn the present paper, the authors aim to analyze the non‐Newtonian effects of Rabinowitsch fluids on the squeeze film performances between wide parallel rectangular plates.Design/methodology/approachBased on the cubic‐stress equation model, a nonlinear squeeze‐film Reynolds‐type equation has been derived. By using a small perturbation method, a closed‐form solution of the squeeze film characteristics is derived for the parallel plates considering the non‐Newtonian effects of cubic stresses.FindingsComparing with the Newtonian‐lubricant parallel plates, the effects of non‐Newtonian cubic‐stress flow rheology provide significant influences upon the squeeze film characteristics.Originality/valueIt is shown that the non‐Newtonian pseudoplastic behavior reduces the load capacity and the response time; however, the effects of non‐Newtonian dilatant lubricant provide an increase in the load‐carrying capacity and therefore lengthen the response time of parallel squeeze‐film plates.