Mitigation of raindrop impact using the multi-functional surface micro-patterns

Abstract

Recently, drone has been used in various fields other than the military (defense) industry, including agriculture, leisure, and transportation. Most drones with high-velocity abilities are significantly affected by rain droplets when flying at this high velocity in rainy weather. As a result, the flying of almost all drones in rainy weather has been prohibited. We propose micro-pattern structures that can maintain hydrophobicity under static conditions and reduce the impact force during dynamic raindrop impingement. The case of a single droplet was analyzed, and the ability to control the collision force based on whether or not a structure exists was demonstrated. Further, the influence of the rebound time on the collision velocity, parameter ratio, and collision angle was analyzed. The analysis was then performed while considering the interaction of multiple droplets (two droplets). The influence of the rebound time, determined by the difference in the velocity at which the two droplets overlap; collision time; and incident angle was analyzed. It was proved that by controlling the dynamic flow characteristics through and rebound time of water droplets through surface shape deformation, the impact force can be minimized.