The deformation and breakup of droplets in airflows is important in many applications of spray and atomization processes. However, the shear effect of airflow has never been reported. In this study, the deformation and breakup of droplets in the shear flow of air is investigated experimentally using high-speed imaging, digital image processing, and particle image velocimetry. We identify a new breakup mode of droplets, i.e., the butterfly breakup, in which the strong aerodynamic pressure on the lower part of the droplet leads to the deflection of the droplet and then the formation of a butterfly-shaped bag. A regime map of the droplet breakup is produced, and the transitions between different modes are obtained based on scaling analysis. The elongation and the fragmentation of the droplet rim are analyzed, and the results show that they are significantly affected by the shear via the formation and the growth of nodes on the rim.

中文翻译：

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空气剪切流中的液滴变形和破裂

在喷雾和雾化过程的许多应用中，气流中液滴的变形和破裂很重要。但是，从未见过气流的剪切作用。在这项研究中，使用高速成像，数字图像处理和粒子图像测速技术，对空气在剪切流中的变形和破裂进行了实验研究。我们确定了一种新的液滴破碎模式，即蝴蝶破碎，其中液滴下部的强大空气动力压力导致液滴偏转，然后形成蝴蝶形袋。产生液滴破裂的状态图，并基于比例分析获得不同模式之间的过渡。分析了液滴边缘的伸长和破碎，