The impact and freezing processes of a water droplet on different cold spherical surfaces

In the present study, we experimentally investigated the impact and freezing processes of a water droplet on different cold spherical surfaces. During the experiment, the spherical surface was put into a cover in which pressurized Argon gas was injected with a purpose to minimize the desublimation of the vapor. Then, the surface temperature was cooled down to a desirable value by a constant temperature bath circulator. After that, a deionized water droplet was released to impinge the spherical surface and its impact and freezing processes were recorded. The results showed that, during the recoiling process of the water droplet, the spreading factors at low surface temperature cases were larger than that of the room temperature case, regardless of the radius of the spherical surface. In addition, the radius of the spherical surface had an apparent effect on the spreading factor when the surface temperature was relatively low (eg. Tw = −9.5 and −14.0 °C). During the freezing process of the water droplet, the change of the temperature as well as the radius of the spherical surface did not lead to an apparent variation of the ice bead shape.