Comparative study of journal bearing performance with ferrofluid and MR fluid as lubricant

Abstract

This paper presents a comparison of performance characteristics of a hydrodynamic journal bearing lubricated with plain engine oil, Ferrofluid and Magnetorheological (MR) fluid. The magnetorheological behaviour of micro and nano sized magnetic particles dispersed in silicone oil is analysed and their effects on bearing characteristics is studied. A test bearing with provision to vary the magnetic field strength is used for the study. The frictional force in the bearing is measured using torque arm principle. Dispersion of the additives is achieved by mechanical agitation and immediately tested to negate the problem of dispersion stability. The variation of frictional force at various bearing speeds is obtained by using plain engine oil as lubricant and then compared with the frictional force variation on lubricating with MR fluids and Ferrofluids of different volume fractions subjected to varying magnetic field strengths. It was observed that the MR Fluids show a significant change in rheological characteristics for varying strengths of magnetic fields. The frictional forces at the bearing surface when lubricated with magnetized MR fluid was much higher compared to that generated with plain engine oil; however the frictional force generated when lubricated with magnetized Ferrofluid was much lower than the frictional force in MR Fluid lubrication subjected to the same magnetic field. Results show significant increase in load bearing capacity of journal bearing when lubricated with MR fluids as opposed to plain engine oil.