Static characteristics of ferrofluid finite journal bearing considering rotational viscosity effect

Abstract

Considering the rotation of ferromagnetic particles, the present study investigates hydrodynamic lubrication by ferrofluids of finite journal bearings using the Shliomis model. A magnetic field created by displaced finite wire is used. A numerical solution for the modified Reynolds equation using the finite difference method is obtained. Static characteristics of finite journal bearings are analysed using three control parameters: rotational viscosity, magnetization and volume concentration of the ferromagnetic particles. It is shown that the pressure, load capacity, attitude angle and side leakage increase and the friction coefficient decreases when increasing the value of each control parameter. Similar trends are also obtained when increasing values of eccentricity for a fixed value of each control parameter except for the decrease of the attitude angle. , 21 H is the magnetic field intensity and M 0 is the equilibrium magnetization given by the Langevin formula 8 : 206 S. LAGHRABLI ET AL.

Ferrofluid lubrication of finite journal bearings using Jenkins model

“…The converging-diverging geometry of a journal bearing gives place to the rupture of the film (cavitation's phenomenon) in the divergent space when the pressure becomes less than atmospheric pressure. For us to resolve the Equation 13, the boundary conditions used are e p θ; e z ¼ 0:…”

“…Taking into account the ferromagnetic particles rotation, Shliomis proposed a ferrofluid flow model. Using this model for different lubrication bearings, researchers found that Brownian motion of the lubricant together with rotation of the magnetic moments within the particles produces rotational viscosity, which supports more load.…”

Rotational viscosity effect on the stability of finite journal bearings lubricated by ferrofluids

“…Indeed, proper rotation of ferromagnetic particles within the carrier base fluid in the presence of magnetic fields affects the fluid viscosity and thus the journal bearing characteristics. Laghrabli et al [19,20] investigated the influence of ferromagnetic particles rotation on the static behavior of finite journal bearing operating with ferrofluids under the effect of a magnetic field generated by a finite wire. Using both Shliomis and Jenkins models, these authors calculated the journal bearing static characteristics and they confirmed that the use of magnetic fluids, compared to Newtonian ones, increases de pressure and consequently the load carrying capacity of the journal bearing.…”

Load and stiffness of a hydrostatic bearing lubricated with a Bingham plastic fluid

“…This locally changes the effective viscosity, locally changing the resistance of the lubricant transportation. In addition, often these effects are accompanied by an attracting force between the fluid and the field, giving rise to an extra body force in the lubrication layer (Laghrabli et al, 2017a(Laghrabli et al, , 2017b. In general, it can be said that locally changing this rheological behaviour has similar effects as locally changing the geometry of the bearing van Ostayen, 2017a, 2017b).…”