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滴状冷凝过程中,存在蒸汽流动对液滴的吹扫作用,液滴在蒸汽剪切作用下克服壁面黏附变形和运动,液滴运动速度越大,冷凝传热性能越高。但是液滴在蒸汽作用下变形和运动的细节还不清晰,蒸汽速度对液滴变形和运动的影响机理还不明确。本文采用自由能格子Boltzmann方法研究了在不同蒸汽速度剪切作用下,液滴在具有不同润湿性固体表面上的变形和运动过程,分析了蒸汽速度和接触角对液滴变形和运动的影响机制,结果显示随着蒸汽速度的增加,液滴变形越大,液滴在固体表面的运动速度越大,停留时间越短,有利于液滴的移除和表面更新,相同蒸汽速度的作用下,液滴在接触角大的固体表面上变形和运动速度越大,也有利于液滴的移除和表面更新。从而定性或半定量地揭示了蒸汽速度影响蒸汽滴状冷凝传热的物理机制。
During the droplet condensation process, there is a purge effect of the steam flow on the droplet. The droplet overcomes the deformation and movement of the wall sticking under the action of the steam shear. The larger the droplet movement velocity is, the higher the condensation heat transfer performance is. However, the details of the deformation and the movement of the droplets under the action of steam are not clear yet. The mechanism of the influence of the steam velocity on the deformation and the movement of the droplets is not yet clear. In this paper, the free-energy lattice Boltzmann method was used to study the deformation and movement of droplets on solid surfaces with different wettability at different steam shear rates. The effects of steam velocity and contact angle on droplet deformation and movement were also analyzed Mechanism, the results show that with the increase of steam velocity, the larger the droplet deformation, the greater the velocity of the droplets moving on the solid surface, the shorter the residence time is conducive to the droplet removal and surface renewal, the same steam velocity , Droplet on the contact angle of the solid surface deformation and the greater the speed of movement, but also conducive to the removal of droplets and surface renewal. Which qualitatively or semi-quantitatively reveals the physical mechanism that the steam velocity affects the heat transfer of steam drop condensation.