화학공학소재연구정보센터
KAGAKU KOGAKU RONBUNSHU, Vol.22, No.5, 1222-1229, 1996
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 experimental approaches. In the theoretical analysis, a momentum conservation equation of a particle, the first order ordinary differential equation in a lagrangian frame work, was solved to obtain the velocity field of particles by using a method of the fourth order Runge-Kutta. Thereafter, a numerical integration of the velocity field was performed to 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 lifting 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 particles were circulating between the two electrodes. The particle velocities obtained by the theoretical and the experimental approaches were approximately identical. A simple formula for the prediction of particle's velocity field was derived by using a curve to fit the results of the numerical simulations. This could make relations between both the Reynolds number on the basis of a particle and other dimensionless numbers consisting of both external forces and locations. The predictions with the formula showed that in the case of a small-sized particle, the velocity of particles increases with the increase in particle diameter, because of viscous force dominating and that in the case of a large-sized particle, the velocity decreased with the increase of the particle diameter because of gravity force dominating.