Abstract The present work addresses the influence of the wall superheat, drop impact velocity, and impact diameter on hydrodynamics, heat transport, and evaporation during drop impingement onto a heated solid wall in a pure vapor atmosphere. A generic experimental setup has been designed and built with a temperature-controlled cell that allows investigation of drop impingement in a pure vapor atmosphere. Therein a single drop is generated and falls onto a heated surface due to gravity. The experiments are conducted with refrigerant FC − 72 . The heated surface is formed by a thin metallic layer coated onto an infrared transparent glass, so that the temperature field of the solid-fluid interface can be observed from below with an infrared camera at high spatial and temporal resolution. The heat flux field is derived from the temperature field using a dedicated post-processing procedure. The dynamic evolution of contact line radius is derived using image analysis. The drop shape is observed with a high speed camera, which is synchronized with the infrared camera. Experimental and numerical results for contact line radius and heat flow evolution are compared with each other. This gives an insight to the governing heat transport mechanism during different phases of drop impingement. Experimental and numerical parameter studies reveal that higher wall superheats, higher impact velocities, or larger drop diameters each result in increasing heat flow after the impact. The maximum spreading radius after impingement is increasing with rising impact velocity or impact diameter, and decreasing with rising wall superheat.

中文翻译：

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液滴撞击热壁期间的传热：壁过热、撞击速度和液滴直径的影响

摘要 目前的工作解决了壁过热、液滴撞击速度和撞击直径对纯蒸汽气氛中液滴撞击加热固体壁时流体动力学、热传输和蒸发的影响。一个通用的实验装置已经被设计和建造了一个温控单元，可以在纯蒸汽气氛中研究液滴撞击。其中产生一滴液滴并由于重力而落在加热的表面上。实验是用制冷剂 FC - 72 进行的。受热表面由涂覆在红外透明玻璃上的薄金属层形成，因此可以使用红外相机以高时空分辨率从下方观察固-流体界面的温度场。热通量场是使用专用的后处理程序从温度场导出的。接触线半径的动态演化是使用图像分析得出的。使用与红外相机同步的高速相机观察液滴形状。接触线半径和热流演变的实验和数值结果相互比较。这让我们深入了解液滴撞击不同阶段的控制热传输机制。实验和数值参数研究表明，更高的壁过热度、更高的冲击速度或更大的液滴直径都会导致冲击后的热流增加。冲击后的最大扩散半径随着冲击速度或冲击直径的增加而增加，随着壁面过热度的增加而减小。