Transactions of Nanjing University of Aeronautics & Astronautics
Numerical Investigation on Droplet Impact and Freezing
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Abstract:
The impact and freezing of micro-sized droplets on cold surface is simulated by the developed numerical methods which couple the multiphase lattice Boltzmann flux solver to simulate the flow field， the phase field method to track the droplet-air interface， and the enthalpy model to determine the liquid-ice interface. The accuracy and reliability of the numerical method are validated by the comparison between the predicted morphology of the droplet impact and freezing on the surface and that from the experiment. The dynamic freezing process is investigated considering the effects of the droplet size， the impact velocity and the temperature of the cold surface. The results show that the freezing of the droplet bottom inhibits the rebound after the droplet spreading， and it may even form a hat-like shape. For the droplet with higher velocity， the ice develops faster in the radial direction and the heat transfer between the droplet and surface is enhanced. In addition， the temperature governs the dynamic behavior of the droplet center. When the surface is colder， it may form a crater in the center. The analysis on the temperature distribution inside the droplet shows that the heat flux decreases with the increasing distance to the cold surface. Moreover， with the ice growing， the decreased temperature in symmetric axis is not proportional to the surface temperature. The dimensionless temperature inside the ice becomes lower for the colder surface due to the increased temperature difference.
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Project Supported:
This work was supported by the National Natural Science Foundation of China （No.11832012） and the National Major Scientific Research Instrument Development Project （No.12227802）.
Clc Number:
V211.3
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