The squeeze film in a porous composite slider bearing

The squeeze film behaviour in a porous composite slider bearing is analysed. Expressions for the pressure, the load capacity, the friction and the position of the centre of pressure are obtained. The pressure, load capacity and friction are increased owing to the squeeze and the position of the centre of pressure moves slightly towards the inlet face. An expression for the time-height relation is also obtained. The response time for a composite slider bearing is greater than that for an inclined slider bearing.     

Magnetic-fluid-based porous inclined slider bearing

A porous inclined slider bearing, lubricated with a magnetic fluid, in the presence of an externally applied magnetic field which is oblique to the lower surface of the bearing is discussed. The load capacity of the magnetic-fluid-based porous inclined slider bearing is found to be greater than that of a viscous porous inclined slider bearing. It is shown that the magnetic-fluid-based porous inclined slider bearing has a performance superior to that of the viscous porous inclined slider bearing.     

Analysis of a porous inclined slider bearing with an azimuthal magnetic field

The effects of an applied azimuthal magnetic field and a porous facing of variable thickness on an inclined slider bearing with an electrically conducting lubricant are theoretically investigated. Expressions for pressure, load capacity, friction and the position for the centre of pressure are derived for both open-circuit and short-circuit cases. The case when the magnetic field is absent is also examined.     

Ferrofluid lubrication in porous inclined slider bearing with velocity slip

The effects of slip velocity and the material constant in a porous inclined slider bearing lubricated with a ferrofluid were theoretically studied by using Jenkins model. Expressions were obtained for pressure, load capacity, friction on the slider, coefficient of friction and position of the centre of pressure. The increase in slip parameter caused decrease in load capacity as well as friction and increase in the coefficient of friction without altering the centre of pressure much. As the material constant increased, the load capacity decreased, friction and coefficient of friction increased and the position of the centre of pressure shifted slightly towards the inlet of the bearing.     

An inclined porous slider bearing with a transverse magnetic field

A hydromagnetic inclined porous slider bearing with a transverse magnetic field is analysed. Expressions for various bearing characteristics are obtained for large and small Hartmann numbers. The dimensionless load capacity, friction and centre of pressure are computed for large Hartmann numbers in the open-circuit case; the load capacity and friction increase markedly with increasing Hartmann number.     

Micropolar fluid squeeze film lubrication of finite porous journal bearing

In this paper, the effect of micropolar fluid on the static and dynamic characteristics of squeeze film lubrication in finite porous journal bearings is studied. The finite modified Reynolds equation is solved numerically using the finite difference technique and the squeeze film characteristics are obtained. According to the results obtained, the micropolar fluid effect significantly increases the squeeze film pressure and the load-carrying capacity as compared to the corresponding Newtonian case. Under cyclic load, the effect of micropolar fluid is to reduce the velocity of the journal centre. Effect of porous matrix is to reduce the film pressure, load-carrying capacity and to increase the journal centre velocity.     

Analysis of normal stress effects in a squeeze film porous bearing

An analytical study of a porous bearing lubricated by a second-order fluid is considered. This investigation explains the working of general porous bearings and, in particular, describes the lubrication aspects of synovial joints. An approximate method for the solution of the governing fluid film equation and Darcy's equation for a porous region is used. Exact expressions for dimensionless pressure, load capacity and response time are obtained. The load capacity and response time for the diseased joint decrease compared with the healthy joint. The decrease in permeability of cartilage enhances the load capacity.     

The hydromagnetic squeeze film bearing with an azimuthal magnetic field

The hydromagnetic squeeze film between circular plates with an imposed azimuthal magnetic field and a voltage between the plates is analysed. Two cases are discussed: when the voltage between the plates is kept constant and when the current between the plates is kept constant. In both cases it is shown that the rate of squeeze can be decreased under appropriate conditions.     

The optimum profile for a porous slider bearing

The load capacity of a porous slider bearing was investigated. The optimum profile was found to be a step form with the riser location and step height ratio depending on the porosity. Porosity decreases the load capacity of a slider bearing. A porous slider bearing of optimum profile supports more load than a porous inclined slider bearing     

The magnetohydrodynamic inclined slider bearing with a transverse magnetic field

The magnetohydrodynamic inclined slider bearing is analyzed under general electrical loading conditions. The magnetic field is applied normal to the bearing surface, and the external electrical circuit is assumed to be fixed in either the slider or bearing, the two situations being related by Lorentz transformations. It is found that significant load increases can be effected by supplying external power, and if the Hartmann number is large enough, open circuit conditions can give rise to greatly increased load capacities. Analytical solutions are presented for large and very small values of Hartmann number and the results can easily be extrapolated for values of Hartmann numbers in between.     

Analysis of an anisotropic porous slider bearing considering slip velocity

A porous slider bearing with anisotropic permeability and slip velocity is considered. Expressions for the load-carrying capacity, friction, coefficient of friction and the position of the centre of pressure are obtained in integral form. Anisotropic permeability and slip affect these bearing characteristics.     

The squeeze film between rotating porous annular disks

The problem of a squeeze film between two rotating disks, one with a porous facing, is analyzed. The analytical model takes account of the porosity of one disk and the inertia due to centrifugal force on the fluid both in the film and in the porous region. The governing equations are derived according to lubrication theory. It is found that the fluid in the film region satisfies the modified Reynolds equation and the flow in the porous region satisfies Poisson's equation. The problem is solved analytically using Fourier expansions. Solutions for load capacity and pressure distribution are presented in series form. The film-thickness and time relation is given in integral form. Results are plotted for selected parameter values. The conditions under which inertia effects can be important are determined and as a result the criteria for neglecting the inertia effects are given.     

Ferrofluid squeeze film in a long journal bearing

A theoretical study and comparison were made of squeeze film behaviour in an infinitely long journal bearing using the ferrofluid flow models of Neuringer–Rosensweig, Jenkins and Shliomis with uniform and non-uniform magnetic fields. Expressions were obtained for the pressure, load capacity and response time of the squeeze film using the flow models of Jenkins as well as Shliomis. The results corresponding to the Neuringer–Rosensweig model were deduced from the Jenkins model. Computed values of dimensionless load capacity and response time were displayed in tabular form. Their values increased with increasing values of the eccentricity ratio in all the three models. They decreased or increased according to whether the values increased were those of the Jenkins material constant or the rotational viscosity parameter of Shliomis. A uniform magnetic field could not produce magnetic pressure in the Neuringer–Rosensweig model, but it could affect the bearing characteristics in the Shliomis model owing to the rotational viscosity. The load capacity and squeeze time are more in the case of a non-uniform magnetic field than in the case of a uniform magnetic field.     

Hydromagnetic squeeze film behavior in porous circular disks

An analysis is presented of the effect of a uniform transverse magnetic field on the squeeze film behavior when a circular disk with a porous facing approaches another disk with uniform velocity. Results for the pressure distribution, load-carrying capacity and film thickness are given as functions of time.     

Ferrofluid-based annular squeeze film bearing with the effects of roughness and micromodel patterns of porous structures

ABSTRACT

Based on the ferrohydrodynamic theory by R.E. Rosensweig and roughness effects by Christensen’s stochastic theory, a mathematical model of ferrofluid lubricated flat (parallel) annular disks (plates or surfaces) squeeze film bearing, is developed with the effects of porosity at the upper disk, circumferential or radial roughness at the lower disk and radially variable magnetic field. The validity of the Darcy’s law is assumed for the porous matrix. The resultant modified Reynolds-Darcy equation is solved in terms of Bessel function. Expressions for dimensionless load-carrying capacity are obtained and computed. The results for circumferential roughness pattern show that dimensionless load-carrying capacity increases when thickness & permeability of the porous matrix decreases, and effect of surface roughness & width of the annular part increases. The effects of micromodel patterns of two different porous structures are also discussed. Slightly better performances of the bearing are observed for globular sphere permeability model. A comparative study is also made when lower disk is circumferentially rough or radially rough or smooth for globular sphere model.     

The hydromagnetic squeeze film between porous circular disks with velocity slip

The effect of velocity slip on the behaviour of a squeeze film between two circular disks when a uniform magnetic field is applied between them was studied. The upper disk which has a porous facing backed by a solid housing approaches the lower disk with a uniform velocity. Results are presented for the pressure distribution, the load-carrying capacity and the film thickness as a function of time. The load-carrying capacity decreases as the permeability parameter increases and decreases further as the slip parameter increases.     

The magnetohydrodynamic composite slider bearing

In this paper, the case of a composite slider bearing with a magnetic field applied tangentially to the bearing and perpendicular to the direction of motion, is considered. The load capacity and other characteristics are determined and it is shown that the load capacity increases as the strength of the magnetic field increases.     

Hydrodynamic lubrication of a porous slider bearing with slip velocity

An inclined porous slider bearing is analysed with slip velocity at the porous boundary considered. The expressions for dimensionless loadcarrying capacity, friction and the centre of pressure are obtained in the form of integrals. Minimization of the slip parameter is essential to increase the load capacity.     

Flow and thermal characteristics of a circular porous slider bearing

An incompressible newtonian fluid is forced through the porous bottom of a circular slider which is moving laterally on a horizontal plane. The effects of mass injection and lateral velocity on the heat generated by viscous dissipation are investigated by solving the governing boundary layer equations using numerical integration techniques. Numerical results are presented for the velocity and temperature distributions as well as for the wall derivatives of the velocity and thermal functions. The range of Prandtl numbers investigated varies from 0.7 to 10 while the cross-flow Reynolds numbers and translational Reynolds numbers range from 0.01 to 50 and 1 to 1000 respectively.