We experimentally investigate the deformation and breakup of droplets interacting with an oblique continuous air stream. A high-speed imaging system is employed to record the trajectories and topological changes of the droplets of different liquids. The droplet size, the orientation of the air nozzle to the horizontal and fluid properties (surface tension and viscosity) are varied to study different breakup modes. We found that droplet possessing initial momentum prior to entering the continuous air stream exhibits a variation in the required Weber number for the vibrational to the bag breakup transition with a change in the angle of the air stream. The critical Weber numbers $(We_{cr})$ for the bag-type breakup are obtained as a function of the Eotvos number $(Eo)$, angle of inclination of the air stream $(\alpha)$ and the Ohnesorge number $(Oh)$. It is found that although the droplet follows a rectilinear motion initially that transforms to a curvilinear motion at later times when the droplet undergoes topological changes. The apparent acceleration of the droplet and its size influence the critical Weber number for the bag breakup mode. The departure from the cross-flow arrangement shows a sharp decrease in the critical Weber number for the bag breakup which asymptotically reaches to a value associated with the in-line (opposed) flow configuration for the droplet breakup.

中文翻译：

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倾斜连续气流中液滴的变形和破碎

我们通过实验研究了与倾斜的连续气流相互作用的液滴的变形和破碎。采用高速成像系统记录不同液体液滴的轨迹和拓扑变化。液滴尺寸、空气喷嘴的水平方向和流体特性（表面张力和粘度）是不同的，以研究不同的破碎模式。我们发现，在进入连续气流之前，液滴具有初始动量，随着气流角度的变化，从振动到袋子破裂的过渡所需的韦伯数会发生变化。袋型破裂的临界韦伯数 $(We_{cr})$ 作为 Eotvos 数 $(Eo)$、气流倾角 $(\alpha)$ 和 Ohnesorge 数的函数获得$（哦）$。研究发现，虽然液滴最初遵循直线运动，但当液滴经历拓扑变化时，随后会转变为曲线运动。液滴的表观加速度及其大小影响袋子破裂模式的临界韦伯数。与错流排列的背离显示袋破裂的临界韦伯数急剧下降，其渐近地达到与液滴破裂的在线（相反）流动配置相关联的值。