液滴撞击超疏水单狭缝表面的实验研究

Experimental Study of Droplet Impact on Superhydrophobic Single-Slot Surfaces

  • 摘要: 液滴撞击超疏水表面的动力学研究多集中于无宏观几何特征的常规表面,对实际工程中广泛存在的具有宏观结构的非常规表面关注不足。本文通过实验探究了液滴撞击超疏水单狭缝表面的动力学行为,系统考察了无量纲狭缝宽度(狭缝实际宽度与液滴初始直径之比,0.09~0.54)与韦伯数(4.03~36.59)对液滴铺展、回缩、穿透及破碎过程的影响。实验观察到完整回弹、回弹并部分穿透、破碎并部分穿透以及完全穿透4种典型行为,并绘制了其对应的参数相图。液滴最大铺展直径随狭缝宽度增加而逐渐减小。通过考虑狭缝宽度和液体穿透高度建立了修正后的最大铺展系数与韦伯数的理论预测模型,理论值和实验值取得了良好的一致性。此外,由于部分液体在撞击过程中穿透狭缝,导致参与铺展与回缩的有效质量减少,使得液滴与表面的接触时间显著缩短。

     

    Abstract: Existing studies of droplet impact dynamics on superhydrophobic surfaces have predominantly focused on conventional substrates lacking macroscopic geometric features, while comparatively limited attention has been given to non-conventional surfaces with macro-structures that are common in practical engineering. In this study, we experimentally investigate the impact dynamics of droplets on superhydrophobic surfaces featuring a single macroscopic slot. We systematically examine the effects of the dimensionless slot width (the ratio of the actual slot width to the initial droplet diameter, 0.09–0.54) and the Weber number (4.03–36.59) on droplet spreading, retraction, penetration, and fragmentation. Four characteristic regimes are observed—complete rebound, rebound with partial penetration, fragmentation with partial penetration, and full penetration—and their corresponding parameter maps are constructed. The maximum spreading diameter decreases progressively as the slot width increases. By accounting for both the slot width and liquid penetration height, a modified theoretical model is developed to predict the maximum spreading coefficient as a function of the Weber number, achieving great agreement with experimental measurements. Moreover, partial liquid penetration during impact reduces the effective mass involved in spreading and retraction, leading to a significant reduction in the droplet–surface contact time.

     

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