LIFTING VELOCITY OF AN INDUCTION-CHARGED ALUMINA PARTICLE IN HORIZONTALLY SET PARALLEL-PLATE ELECTRODES

The lifting velocity of an induction-charged particle in horizontally set parallel plate electrodes was studied by both theoretical and expe rimental approaches. In the theoretical analysis, a momentum conservat ion equation of a particle, the first order ordinary differential equa tion in a lagrangian frame work, was solved to obtain the velocity fie ld of particles by using a method of the fourth order Runge-Kutta. The reafter, a numerical integration of the velocity field was performed t o define locations of particles. For the experiment, by using alumina powders with A 4 paper-sized electrodes the maximum lifting height of a particle above the upper electrode was measured to estimate the lift ing velocity of a particle in the first few seconds after high voltage was supplied, and a laser doppler velocity meter was used to measure the velocity fields of particles in the subsequent period when particl es were circulating between the two electrodes. The particle velocitie s obtained by the theoretical and the experimental approaches were app roximately identical. A simple formula for the prediction of particle' s velocity field was derived by using a curve to fit the results of th e numerical simulations. This could make relations between both the Re ynolds number on the basis of a particle and other dimensionless numbe rs consisting of both external forces and locations. The predictions w ith the formula showed that in the case of a small-sized particle, the velocity of particles increases with the increase in particle diamete r, because of viscous force dominating and that in the case of a large -sized particle, the velocity decreased with the increase of the parti cle diameter because of gravity force dominating.