Hydrodynamic and electrostatic interactions of water droplet pairs in oil and electrocoalescence

Abstract

Abstract This paper presents an experimental study of falling droplet pair interactions until their electrocoalescence in axisymmetric configuration: the drop pair axis is parallel to the falling direction and to the applied electric field. Generation of droplet pairs from single needle by EHD injection method allows obtaining droplets smaller than in existing data, their diameters ranging between a few tens to two hundred microns. Droplets diameters and electric charges are revealed by comparing the experimental falling velocity to calculations taking into account hydrodynamic and electrostatic interactions. To validate the method and corresponding experimental data, mass and electric charge conservations are checked during the coalescence and comparison is proposed with numerical simulation of droplet pair behavior.