Thermal Effects on Hydrodynamic Journal Bearings Lubricated by Magnetic Fluids with Couple Stresses

Based on the momentum and continuity equations for ferrofluid under an applied magnetic field, assuming linear behavior for the magnetic material of the ferrofluid, and using carrying current concentric finite wire magnetic field model, the magnetic force was calculated. A modified Reynolds equation is obtained. It is simultaneously solved with the energy equation numerically by the finite difference technique. The pressure and temperature distributions have been obtained under various couple stress parameter. The solution renders the bearing performance characteristics namely; load carrying capacity, attitude angle of the journal center, frictional force at the journal surface, friction coefficient and bearing side leakage. Based on the micro-continuum theory, and by taking into account the couple stresses due to the microstructure additives, the effects of couple stresses on the performance of a finite hydrodynamic journal bearings were studied. The results have shown that fluids with couple stresses are better than Newtonian fluids. Index Term-Magnetized journal bearings; Ferrofluid lubricants; Static characteristics; Couple stresses.