Abstract:
The physical mechanism of droplet impact on solid surface under the action of electric field has been widely used in the fields of electrostatic spraying, microfluidic control, icing of high voltage power lines, etc. The visual experiment was used to study the motion process and morphological changes of droplet impacting the wall under applied electric field, especially in the stages of shrinkage, stretching and spraying. The effects of electric field intensity, low Weber number and surface wettability on droplet dynamic behavior are also considered. The results show that when the impact velocity is constant, the droplet impact on the wall will exhibit three different modes with the increase of field strength due to the combined action of inertia force, gravity, surface tension, electrostatic force and viscous dissipation. The change of electric field intensity has no obvious effect on the droplet spreading coefficient, but can significantly promote the increase of droplet stretching coefficient. The threshold relationship between low Weber number, electric capillarity number and modes is obtained. Under the condition of strong electric field, droplet ejection phenomenon leads to liquid loss, and for the wall surface with different wettability, the amount of liquid remaining in droplet and the time to reach the ejection state are different.