Experimental Investigation on Dynamic Characteristics of Highly Viscous Droplets and Liquid Bridges Under the Influence of Electric Fields

Formation of highly viscous droplets and liquid bridges under the influence of electric fields is widely used in material preparation, food processing, inkjet printing and 3D (three-dimensional) printing. To investigate the formation of droplets and liquid bridges, a visual experimental platform is designed and constructed. A non-uniform electric field is constructed using a metal capillary and a copper pole plate. By varying the voltage, capillary diameter and liquid volume flow rate, the formation of silicone oil droplets and liquid bridges is investigated. The influence of electric forces to the coiling effect of viscous fluids is researched, which has not been thoroughly investigated in previous research. The results verify that at low volume flow rates and small pipe diameters, the silicone oil formation pattern is in the droplet state. As the voltage increases, the droplet formation period decreases. When the voltage is gradually increased at higher volume flow rates, the silicone oil changes from the initial liquid bridge to the droplet. This experimental phenomenon demonstrates that the electric field can alter the instability of the jet. In the case of small volume flow rates and large pipe diameter, the droplet formation state changes from droplet mode to multi-strand jet mode after the voltage is increased to a certain level. At large pipe diameters and large volume flows rates, the liquid bridge mode with a rope coiling effect occurs due to the highly viscous nature of the silicone oil, but the rope coiling effect disappears after a certain voltage is applied.