论文部分内容阅读
超疏水表面上由冷凝液滴的合并触发的液滴弹跳现象在自清洁、强化传热、防结霜等工程领域均有广阔的应用前景.本文建立了一个能量模型以分析多液滴合并触发的液滴弹跳现象.依据本文模型,在液滴弹跳过程中,涉及到表面能、黏性耗散、重力势能、阻滞功、振动动能和平动动能等能量形式的变化及转换,当有更多的表面能转化为平动动能时,液滴弹跳速度会更快.结果表明,多液滴合并能够释放更多的表面能,分布更集中的液滴之间的合并有利于获得更多的平动动能,使液滴弹跳速度更大.此外,存在最小的临界液滴半径和半径比,小于该半径或半径比时,不会发生液滴弹跳.随合并液滴数量的增加,该最小的临界液滴半径和半径比均减小.“,”Self-propelled droplet jumping phenomenon during condensation on a superhydrophobic surface has many potential applications in engineering fields such as heat transfer enhancement,anti-icing surface and self-cleaning surface.This paper presented a theoretical model to calculate the jumping velocity and analyze the triggering conditions for the droplet jumping triggered by multidroplet coalescence.In the model,various forms of energy were considered including the released surface energy,the viscous dissipation,the negative energy due to the surface contact angle hysteresis,the gravitational potential energy and the effective kinetic energy.Droplet coalescence which releases more surface energy and holds more effective kinetic energy achieves a larger junping velocity.The results show that multidroplet coalescence with equaled droplet size and concentrated droplet location is advantageous for increasing the droplet jumping velocity.Increasing the surface contact angle and decreasing the surface contact angle hysteresis are also advantageous for the droplet jumping.In fact,these influencing factors are coupled together.If one of them is changed,the others must change to make a compromise to meet the minimum requirement for droplet jumping.