Investigations on Dielectric Particle Behaviors under the Effect of a Strong Electric Field

Electrification and levitation of particles in an external electric field significantly influence the powder handling process. In this work, the behavior of polarized particles subjected to electrostatic forces induced by an external electric field is studied both experimentally and theoretically. In the experiment, two parallel electrodes are horizontally placed in a chamber with a well-controlled relative humidity. Dielectric particles of different diameters (from 150μm to 10μm) are then uniformly dispersed on the electrode below, which is connected to a dc voltage (from +3kV to +5kV). The particles are polarized and energized by the external electrostatic field. Various particle behaviors, including levitation, oscillation and formation of fractal agglomerates and straight particle chains, are observed under different conditions. Then we run simulations using adhesive Discrete Element Method (DEM), which well reproduces the experimental observations. Based on extensive numerical simulations, we propose simple criterions that allows one to determine the dominant behavior of particles in the system.