Abstract In this study, we propose an analytical model to predict dynamic Leidenfrost temperature for saturated water drops impacting on superheated smooth and textured surfaces. To define the Leidenfrost triggering mechanism, this model postulates a balance relation between the downward pressure by the drop itself and the resistant pressure arising from vaporization from the base of the drop; the former is expressed as the sum of dynamic and water hammer pressures induced by the drop motion while the latter is modeled with pressure buildup effect due to vapor flow within the thin film under the drop. The textured surfaces have uniformly distributed circular pillars with ~10 µm length scale, and the center-to-center pitch of the pillars varies from 15 to 120 µm. The experimental results show that the Leidenfrost temperature on textured surfaces increases at the same Weber number (We), as the pillar pitch becomes coarser. However, the Leidenfrost temperatures on the textured surfaces with relatively fine pitch were found to be rather lower than that on the smooth surface at the same We. Those experimental data are well predicted by the theoretical model, in which two simple equations with two unknowns (Leidenfrost temperature and thickness of thin vapor layer) are derived; one is based on the pressure balance relation and the other postulates an initial transient phase during drop impact.

中文翻译：

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纹理表面上饱和水滴的动态莱顿弗罗斯特温度

摘要 在这项研究中，我们提出了一种分析模型来预测影响过热光滑和纹理表面的饱和水滴的动态莱顿弗罗斯特温度。为了定义 Leidenfrost 触发机制，该模型假设液滴本身的向下压力与液滴底部蒸发产生的阻力之间存在平衡关系；前者表示为由液滴运动引起的动态压力和水锤压力的总和，而后者则用由于液滴下方薄膜内的蒸汽流动引起的压力累积效应建模。带纹理的表面具有均匀分布的圆柱，长度为 ~10 µm，圆柱的中心距从 15 到 120 µm 不等。实验结果表明，当柱间距变粗时，纹理表面上的莱顿弗罗斯特温度以相同的韦伯数 (We) 增加。然而，发现具有相对细间距的纹理表面上的 Leidenfrost 温度远低于相同 We 的光滑表面上的 Leidenfrost 温度。理论模型很好地预测了这些实验数据，其中导出了两个具有两个未知数（莱顿弗罗斯特温度和薄蒸汽层厚度）的简单方程；一种是基于压力平衡关系，另一种是假设跌落冲击期间的初始瞬态阶段。发现具有相对细间距的纹理表面上的 Leidenfrost 温度远低于相同 We 的光滑表面上的 Leidenfrost 温度。理论模型很好地预测了这些实验数据，其中导出了两个具有两个未知数（莱顿弗罗斯特温度和薄蒸汽层厚度）的简单方程；一种是基于压力平衡关系，另一种是假设跌落冲击期间的初始瞬态阶段。发现具有相对细间距的纹理表面上的 Leidenfrost 温度远低于相同 We 的光滑表面上的 Leidenfrost 温度。理论模型很好地预测了这些实验数据，其中导出了两个具有两个未知数（莱顿弗罗斯特温度和薄蒸汽层厚度）的简单方程；一种是基于压力平衡关系，另一种是假设跌落冲击期间的初始瞬态阶段。