Kinetic Behavior of Droplet Impacts on Inclined Surfaces with Different Wettability at Different Temperatures

Superhydrophobic surfaces, a new type of green material, exhibit promising application prospects in the field of anti-/de-icing. In this paper, the kinetic behavior of impinging droplets on surfaces with different temperatures (-25-16 ℃), different inclination angles (0°-60°), and different wettability (hydrophilic and superhydrophobic surfaces) is investigated through experimental comparisons. The variations of the droplet morphology, spreading factor, spreading time, and contact time are analyzed. The results show that the impinging droplets exhibit different kinetic behaviors after spreading due to the different inclination angles and wettability. The maximum spreading factor and spreading time on hydrophilic surfaces increase with the inclination angle. The variation of the spreading time on superhydrophobic surfaces follows the same trend as that on hydrophilic surfaces, while the maximum spreading factor decreases with an increase in the inclination angle, especially at T_s>-25 ℃; Compared to hydrophilic surfaces, the impinging droplets have shorter spreading times on superhydrophobic surfaces, which can reach about 10 times at T_s=-25 ℃. Increasing the wall inclination angle breaks the symmetric bounce of the droplets on the horizontal superhydrophobic surface, thereby shortening the contact time of the droplets. This suggests that increasing the inclination angle can effectively inhibit the freezing of water droplets.