Contactless electrostatic shaping of a capillary jet for drop-on-demand purposes

Abstract

The contactless electrostatic shaping of a capillary jet can be adjusted so as to generate a monodisperse spray in the jetting regime. To demonstrate this, an actuator based on stacked electrodes is developed to generate a spatially modulated electric stress. The latter promotes the parametric excitation of a wavelength along a deformed capillary jet. The objective is to better control the breakup length of the capillary jet and to phase lock drop ejection. Experiments are carried out based on light absorption and fast imaging. The breakup length and the drop size distribution are measured. The comparison with a stability model allows us to identify resonant frequencies which monitor the size or the number density of drops. The concept of synchronization frequencies is introduced here with possible use in future developments of electrodynamic actuators.