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ORIGINAL ARTICLE

Experimental Investigation on Droplet Deformation and Breakup under Uniform DC Electric Field Dian Li 1 & Tai Wang 1

&

Shuo Chen 1 & Qingyuan Liu 1 & Yingbai Xie 1 & Chuntao Liu 1

Received: 1 January 2020 / Accepted: 4 June 2020 # Springer Nature B.V. 2020

Abstract In order to understand the dynamic behaviors of the charged water droplet in the presence of electric field, the experimental investigation is conducted in this paper. A uniform DC electric field is produced by applying high voltage between two parallel copper plates which are placed horizontally in a silicon oil tank. The variation range of the electric field intensity is 0–6.67 kV/ cm. Under the influence of the electric field, deformation, motion, breakup and other dynamic behaviors of the charged water droplet with the initial diameter of 5.36 mm are observed and analyzed. Results show that the increase in the electric field intensity results in the elongation of the charged droplet. When the electric field intensity increases to 2.5 kV/cm and 3.0 kV/cm, the droplet would deform into an unstable Taylor cone shape, and then the top of droplet breaks up into some daughter droplets. These daughter droplets move up and down between two copper plates. Further increasing the electric field intensity to 3.67 kV/ cm, some of daughter droplets forms a liquid bridge linked the two plates which likes a pearl chain, and then discharge phenomenon occurs. For the enormous electric field intensity of 6.67 kV/cm, numerous tiny droplets, which distribute uniformly in the silicon oil, are produced by the breakup of larger daughter droplets and the large droplet located on the lower plate. This research has certain application value in the fields of oil treatment, electric demulsification and so on. Keywords Electrohydrodynamics . Uniform electric field . Droplet deformation . Droplet breakup . Experimental investigation

Introduction Droplet deformation and motion is a common physical phenomenon widely appearing in many engineering fields, such as power engineering, nuclear engineering, chemical engineering, space engineering and so on. In the droplet dynamics, charged droplets in electric field have some unique dynamic behaviors, which has been applied in ink-jet printing (Yudistira et al. 2010), electrospray (Jaworek 2007), electrocoalescence (Eow et al. 2001), electrified jets (Polyanskikh and Demekhin 2009), heat transfer enhancement (Hader and Jog 1998) and combustion (Imamura et al. 2005). In the microgravity environment, the gravitational acceleration is so small, thus gravity force has no significant effect on droplet dynamics. But applying an electric field on the phase interface, the electric force can replace gravity to * Tai Wang [email protected] 1

School of Energy, Power and Mechanical Engineering, North China Electric Power University, Baoding 071003, China

control the motion of discrete phase (Wang et al. 2016). Based on this, research on the deformation and motion of droplets in the electric field is exceedingly meaningful,