Motion analysis on the particles in a magnetic field detector

This paper, as the title indicates, deals with the depositing mechanism of the particles under the magnetic field in the lubricant for on-line ferrogr aph or oil analysis. Lubricant, containing ferromagnetic particles, is take n as the multiphasic ferromagnetic fluid in ferrograph detecting. By measur ing and regressing, the distribution formulas of magnetic density and magne tic density gradient of an electromagnet are gained. The variance law of vi scosity of lubricant in the non-uniform magnetic field is studied and a vis cosity formula is put forward. The motion law of ferromagnetic particles in the non-uniform magnetic field is studied and a standpoint is put forward, which is that the ferromagnetic particles cannot achieve a constant sinkin g velocity in a non-uniform magnetic field. The factors influencing particl es motion, such as particle diameter, ratio of particles volume and air bub bles, are also studied. Some results are obtained and discussed, which are of practical significance in the research and design of on-line ferrograph and other methods of on-line oil monitoring. (C) 2000 Published by Elsevier Science Ltd.