Combined effect of variable-viscosity and surface roughness on the squeeze film characteristics of infinitely wide rectangular plate with couple stress fluid, velocity-slip and ferrofluid lubricant (original) (raw)
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Performance of Magnetic-Fluid-Based Squeeze Film between Longitudinally Rough Elliptical Plates
ISRN Tribology, 2013
An attempt has been made to analyze the performance of a magnetic fluid-based-squeeze film between longitudinally rough elliptical plates. A magnetic fluid is used as a lubricant while axially symmetric flow of the magnetic fluid between the elliptical plates is taken into consideration under an oblique magnetic field. Bearing surfaces are assumed to be longitudinally rough. The roughness of the bearing surface is characterized by stochastic random variable with nonzero mean, variance, and skewness. The associated averaged Reynolds’ equation is solved with appropriate boundary conditions in dimensionless form to obtain the pressure distribution leading to the calculation of the load-carrying capacity. The results are presented graphically. It is clearly seen that the magnetic fluid lubricant improves the performance of the bearing system. It is interesting to note that the increased load carrying capacity due to magnetic fluid lubricant gets considerably increased due to the combine...
International Journal of Applied Mechanics and Engineering, 2016
In this paper, the solution to a problem of pressure distribution in a curvilinear squeeze film spherical bearing is considered. The equations of motion of an Ellis pseudo-plastic fluid are presented. Using Christensen’s stochastic model of rough surfaces, different forms of Reynolds equation for various types of surface roughness pattern are obtained. The analytical solutions of these equations for the cases of externally pressurized bearing and squeeze film bearing are presented. Analytical solutions for the film pressure are found for the longitudinal and circumferential roughness patterns. As a result the formulae expressing pressure distribution in the clearance of bearing lubricated by an Ellis fluid was obtained. The numerical considerations for a spherical bearing are given in detail.
2017
Efforts have been made to analyze the combined effect of surface roughness and slip velocity on the ferrofluid squeeze film in double layered porous circular plates. The magnetic fluid flow is governed by Neuringer – Roseinweig model while the stochastic modelling of Christensen and Tonder has been adopted to evaluate the effect of transverse roughness. The associated stochastically averaged Reynolds' type equation is solved to obtain the pressure distribution leading to the calculation of load carrying capacity. The results presented in the graphical forms establish that the magnetization offers a limited scope in containing the adverse effect of roughness, porosity, and slip velocity. However, the situation improves when negatively skewed roughness occurs. But for any type of improvement in the bearing performance the slip has to be kept at reduced level even if variance (-ve) is involved.
Curvilinear Squeeze Film Bearing Lubricated with a Dehaven Fluid or with Similar Fluids
International Journal of Applied Mechanics and Engineering, 2017
In the paper, the model of a DeHaven fluid and some other models of non-Newtonian fluids, in which the shear strain rates are known functions of the powers of shear stresses, are considered. It was demonstrated that these models for small values of material constants can be presented in a form similar to the form of a DeHaven fluid. This common form, called a unified model of the DeHaven fluid, was used to consider a curvilinear squeeze film bearing. The equations of motion of the unified model, given in a specific coordinate system are used to derive the Reynolds equation. The solution to the Reynolds equation is obtained by a method of successive approximations. As a result one obtains formulae expressing the pressure distribution and load-carrying capacity. The numerical examples of flows of the unified DeHaven fluid in gaps of two simple squeeze film bearings are presented.
Curvilinear Squeeze Film Bearing with Porous Wall Lubricated by a Rabinowitsch Fluid
International Journal of Applied Mechanics and Engineering, 2017
The present theoretical analysis is to investigate the effect of non-Newtonian lubricant modelled by a Rabinowitsch fluid on the performance of a curvilinear squeeze film bearing with one porous wall. The equations of motion of a Rabinowitsch fluid are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and in a porous layer using the Morgan-Cameron approximation the modified Reynolds equation is obtained. The analytical solution of this equation for the case of a squeeze film bearing is presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. Thrust radial bearing and spherical bearing with a squeeze film are considered as numerical examples.