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In the present study, we carried out an experimental investigation of the impinging and freezing processes of a supercooled large water droplet on an ice surface. One high speed camera was used to measure the dynamic motions of the water droplet while two charge coupled device (CCD) cameras were adopted to obtain the images of the freezing process and the freezing morphologies, respectively. The effects of the water droplet temperature and the ice surface temperature on the impact and freezing processes of the water droplet were carefully evaluated. The results showed that the subcooling degree of the water droplet had an apparent influence not only on the spreading process but on the freezing morphology as well. When the subcooling temperature of the water droplet was high (e.g., Tw = –3.0 °C), a triangle cross-section profile formed. However, once the subcooling temperature of the water droplet was relatively low (e.g., Tw = –9.0 °C), the final ice morphology consisted of two parts: one part was a cone-like bead in the center while the other part was an ice ring at the periphery. Moreover, at the same water droplet temperature, raising the ice surface temperature led to an increase in the maximum spreading factor. [ABSTRACT FROM AUTHOR]

In the present study, we report for the first time the observations of the melting process of an ice bead in a hot shear flow. During the experiment, a water droplet was first deposited onto a glass surface. Then, the surface temperature was cooled down to a desirable subfreezing value by a constant temperature bath circulator and the water droplet turned into an ice bead. After that, the ice bead was exposed to a hot shear flow and its melting process was recorded by two cameras. The results showed that, both the air flow speed and substrate surface temperature had significant effects on the melting process of the ice bead. The increase of the air flow speed resulted in a significant change of the runback phenomenon of the liquid water generated from the melting ice bead. Besides, as the decrease of the substrate surface temperature, the deicing time of the ice bead increased apparently. In addition, during the melting process of the ice bead, the temperatures of two characteristic points along the centerline demonstrated apparent differences. [ABSTRACT FROM AUTHOR]