Electrohydrodynamics of water droplets on polymer surfaces

For a complete comprehension of the phenomena connected with the flashover of polymeric insulators, we must first understand the behavior of sessile water droplets in strong electric fields existing on hydrophobic surfaces. The purpose of this paper is to study the distortion of water droplets under electric stress, which causes electric field enhancement, which is the key phenomenon behind the flashover mechanism of hydrophobic, nonceramic insulators. The electric field intensification caused by water droplets depends on the size, shape, conductivity, and number of droplets, their proximity to each other, surface of the material, and other environmental conditions. Presented in this paper are the results of a parametric study of field distortion of water droplets on polymeric surfaces using commercial simulation software. The results indicate that on polymeric surfaces, the electric field intensity is higher, if the droplet is flatter (lower contact angle), of higher conductivity and if there are many droplets. Comparison of computed results with experimental data shows good correlation.