Experimental study on the deformation of core-shell drop in the presence of high voltage electric field

In this research, the deformation of a core-shell droplet under the influence of high voltage electric field is studied. In order to produce this kind of droplets two coaxial nozzles are utilized. Here, distilled water and transformer oil are fluids used as the core and shell, respectively. Two parallel copper plates connected to a high voltage supplier are considered so as to produce an electric field. By increasing the electrical potential difference, the intensity of electric field and consequently the drop deviation angle increase. At particular electrical potential difference of 8 kV, the core breaks due to the intense electric field, therefore it has a different deformation. After separation of the inner droplet from the outer one, the outer droplet on the grounds of surface tension and inertia forces begins to return to the spherical form. Due to its initial velocity toward positive electrode, the core-shell droplet tends to move in this direction. However, the remaining piece inside the outer droplet tends to move in opposite direction. Eventually, outer droplet deforms and stretches again.