Z. Naturforsch. 68a, 249 – 254
Lubrication Performances of Short Journal Bearings Operating with Non-Newtonian Ferrofluids
1 Department of Mechanical Engineering, Taoyuan Innovation Institute of Technology, Jhongli, Taiwan, R.O.C.
2 Department of Institute of Mechatronic Engineering, National Taipei University of Technology, Taipei, Taiwan, R.O.C.
3 Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan, R.O.C.
Received June 7, 2012 / revised September 21, 2012 / published online February 20, 2013
The lubrication performances of short journal bearings operating with non-Newtonian ferrofluids have been investigated in the present study. Based upon the ferrofluid model of Shliomis and the micro-continuum theory of Stokes, a two-dimensional modified Reynolds equation is derived by taking into account the effects of rotation of ferromagnetic particles and the effects of non-Newtonian properties. As an application, the short-bearing approximation is illustrated. Comparing with the conventional non-ferrofluid case, the short journal bearings with ferrofluids in the presence of magnetic fields result in a higher load capacity. Comparing with the Newtonian ferrofluid case, the non-Newtonian effects of couple stresses provide an enhancement in the load capacity, as well as a reduction in the friction parameter. The inclusion of non-Newtonian couple stresses signifies an improvement in performance characteristics of ferrofluid journal bearings.
Key words: Ferrofluids; Non-Newtonian Effects; Journal Bearings; Reynolds Equation; Steady-State Performances.