| ZHANG Dan,ZHENG Haikun,CHEN Xiaosong,ZHANG Peicheng,SHENG Wei,HAO Xiaoru.Simulation Investigation of Multi-size Droplet Impact and Freeze on Superhydrophobic Surfaces[J],54(6):173-181, 239 |
| Simulation Investigation of Multi-size Droplet Impact and Freeze on Superhydrophobic Surfaces |
| Received:April 20, 2024 Revised:August 30, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.06.016 |
| KeyWord:supercooled water droplets surface phase change kinetic properties heat transfer analysis numerical simulation |
| Author | Institution |
| ZHANG Dan |
School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo , China |
| ZHENG Haikun |
School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo , China;Hami Yu-Xin Energy Industry Institute Co., Ltd, Xinjiang Hami , China |
| CHEN Xiaosong |
School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo , China |
| ZHANG Peicheng |
School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo , China |
| SHENG Wei |
School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo , China;Hami Yu-Xin Energy Industry Institute Co., Ltd, Xinjiang Hami , China |
| HAO Xiaoru |
School of Mechanical and Power Engineering, Henan Polytechnic University, Henan Jiaozuo , China |
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| Abstract: |
| The work aims to study the dynamics and heat transfer characteristics of superhydrophobic surfaces of supercooled droplets with different diameters, and verify the accuracy of the simulations by comparing them with existing experiments and other simulations. Based on the background of the impact of supercooled water droplets in the macroscopic freezing/frosting process, CLSVOF method and solidification-melting model were used to adopt supercooled water droplets with diameters of 3 000, 2 375, 1 750 and 1 125 μm to impact the wall at 1.4 m/s under a temperature of −15 ℃. There were four impact types. The impact of water droplets on icing behavior was simulated. For the superhydrophobic wall surface with a small hysteresis angle, the static contact angle model was used in this example, and the contact angle was 163°. The icing behavior of water droplets hitting was simulated and studied, and the icing dynamics of water droplets hitting were quantitatively analyzed from the perspectives of kinetics and heat transfer, and the dynamic diagram of water droplet impact icing was obtained. The maximum wetting area obtained by simulation was in good agreement with the experimental results, and the deviation was less than 13%. The above results illustrated the feasibility of the simulation to analyze the following icing process of supercooled water droplets. The dynamic process of droplets with different diameters hitting the superhydrophobic wall was similar, but with the increase of the droplet diameter, the time required for the droplets to hit the wall at different stages, the maximum spreading area of the droplets, and the contact time between the droplets and the wall increased by 3.691, 4.444 and 5.867 ms respectively. The simulation results were slightly faster than the experimental results because the static contact angle model used in the simulation ignored the effect of the hysteresis angle. The contact time of the 3 mm droplet was 16.784 ms, and the maximum spreading area was 4.07×10−5 mm2. The contact time of a 1.125 mm droplet was 3.416 ms and the maximum spreading area was 2.76×10−6 mm2. The droplet contact time difference between the two scales was about 4.9 times, and the maximum spreading area had an order of magnitude difference, so the droplet diameter had a great impact on the heat transfer between the droplet and the surface. The heat transfer curves of droplets with different diameters hitting the wall surface show the same trend with time, which firstly increases gradually with the spreading process of the droplets, decreases with the droplet retraction after reaching the maximum heat transfer, and finally approaches 0 W. When the droplet reaches the maximum spreading, the heat transfer of the droplet with a diameter of 3 000 μm fluctuates significantly, because the upper part of the droplet will oscillate strongly before and after the maximum spreading time of the larger droplet, resulting in the change of air bubbles between the surface and the droplet. Through the slope of different stages, it can be seen that with the increase of droplet diameter, the heat transfer rate between the droplet and the wall increases in the spreading stage and the retraction stage, and then approaches 0 W/s as the droplet gradually springs off, and the large diameter water droplet will lead to higher heat transfer compared with the small diameter water droplet. The droplet diameter has a significant effect on the kinetic and thermodynamic properties of the impact process, and the relevant parameters obtained by the simulation are compared with the known experiments and other simulations, which proves the accuracy of the simulation method, and the research results can provide a new reference for the effective removal and anti-icing of multi-size droplets on superhydrophobic surfaces. |
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