【摘要】 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。更多还原

【Abstract】 Droplet could be swept by steam flow during dropwise condensation.Droplet morphology could be deformed and could move on the solid surface overcoming the adhesion work of solid under the steam shearing effect.Steam condensation heat transfer performance becomes high when the steam velocity increases.However,the detailed information of the droplet deformation and motion under steam shearing effect has not been clear.The influence mechanism of steam velocity on droplet deformation and motion has not been completed.Therefore,in this paper,droplet deformation and motion on solid surface with various wettability properties under different steam velocities applying free energy lattice Boltzmann method.The influence mechanism of steam velocity and contact angle on droplet deformation and motion is analyzed.Indicating that droplet deformation and motion velocity increase with the increase of steam velocity and contact angle.The residence time of droplet is shortened and the surface renewal frequency is ascended.As a result,the physical mechanism of steam velocity on dropwise condensation heat transfer is displayed qualitatively and semi-quantitatively.更多还原