MAGNETOPHORETIC MOTION OF MICRON-SIZED MAGNETIC PARTICLES IN THE WORKING GAP OF A MAGNETIC FLUID SEAL

The operational experience of bearing units in technological equipment has been analysed. The use of magnetic fluid seals to enhance the reliability and failure-free operation of equipment has been justified. A method for expanding the application range of seals by adding micron-sized magnetic particles to the working magnetic fluid, in accordance with Ukrainian Patent No. 106420, has been proposed. The distribution of magnetic induction in the active zone of the seal with an increased gap (0.8 mm) has been calculated for two cases—with and without a defect on the shaft surface. A regime where micron-sized magnetic particles are additionally introduced into the working magnetic fluid has been considered. The non-uniform distribution of the field and the vector quantity of the magnetic force acting on microscopic particles in the magnetic fluid has been demonstrated. The distribution of the velocity of these particles under the influence of this force in the active zone of the seal, both with and without a defect on the shaft, has been obtained through calculations. It has been shown that these particles concentrate in areas with non-uniform fields—in the angular zones of the teeth of the magnetic system and near the defect on the shaft. The characteristic transition time for particles with diameters of dp = 0.1; 1 and 10 µm is 630, 6.3, and 0.063 minutes, respectively.