423 / 2022-03-15 21:34:46

Analyzing the Droplet Motion Characteristics on Super-hydrophobic Insulator Surfaces under DC Electric Fields

superhydrophobic insulator,Droplet Motion,DC Electric Fields,non-uniform electric fields

Purpose/Aim

On the surface of superhydrophobic insulating materials, droplets have a unique form of existence, as tiny droplets adhere to the insulating surface with small contact areas,  and the stability of adhesion decreases with the increase of the tilt degree. Existing research shows that on planar superhydrophobic surfaces, applying uniform electric fields can trigger the droplets to move hence improving the cleanliness of the surface. Cleanliness is important for outdoor electrical insulations to maintain their insulating strengths. For insulators, the inclination angles, as well as the electric field strength vary along the radius of its shed. Under this condition, the motion characteristics and mechanism of droplets can be different from those under uniform electric fields and on planar surfaces. To date, the motion characteristics and mechanisms of droplets on superhydrophobic insulators surfaces, which are characterized by non-uniform electric fields and non-planar surfaces are still unclear.

Experimental/Modeling methods

Based on the force analysis of droplets on superhydrophobic insulation surface under DC electric field, the mechanism of the influence of the tilt angle and electric field strength on the motion characteristics of attached droplets is theoretically analyzed, and a theoretical numerical model that can describe the motion characteristics of droplets on non-planar surface and under non-uniform electric field is proposed. The motion of droplets on superhydrophobic insulator surfaces under DC electric field is experimentally observed, and the motion characteristics of droplets superhydrophobic insulator surfaces under non-uniform DC electric field conditions are further analyzed by combining the observed phenomenons and the theoretical model.

Results/discussion

The motion directions and the motion abilities of the droplets locating in different regions on superhydrophobic insulator surfaces under DC electric field are opposite, the observed phenomenons are in consistent with the results predicted by the numerical model.

Conclusions

The numerical model is accurate in describing the motion characteristics of droplets on superhydrophobic insulator surfaces under DC electric fields. There is a critical radius value of insulator shed, the closer the droplet locates to it, the harder it is for the droplet to move. The dielectric force hinders the droplet movement, resulting in a very small acceleration of the electrodynamic motion of the droplet near the center of the insulator.