Supercooled water droplet impact on cold plates having different temperatures and contact angles

The impact process of a water droplet on a cold plate involves fluid dynamics and phase change, existing in aircraft icing, meteorology and refrigeration. It is of key importance to clearly understand this process. In this study, the impact and freezing processes of a supercooled water droplet on different temperature (0°C ~ -25°C) and contact angle (50° ~ 150°) plates are simulated using the VOF model coupled with the Solidification/Melting model, considering the supercooling effect on the droplet physical properties. The comparison of impacting droplet diameters between the experiment and simulation supports the reliability of the model. For a supercooled droplet, the supercooling degree needs to be taken into account in the simulation because of the change in physical properties. The model can reveal the impact and freezing behaviors and be used to study the ice accretion mechanism. The results show that droplet spreads at the early stage until its diameter reaches a maximum and it then shrinks at the later stage until its diameter attains a stable value. As the temperature goes down, the maximum diameter remains almost the same while the stable droplet diameter becomes larger because of the existence of solidification. As the contact angle increases, the shrinkage occurs earlier, leading to a smaller maximum diameter. These results may improve our understanding of anti-ice/-frost of superhydrophobic surfaces.