Abstract The present study experimentally examines the secondary atomization arising from the impingement of a water-in-oil emulsion drop onto a hot sapphire glass surface. The main aim of this study is to characterize secondary droplets emerged from the rim and lamella disruption. Drop impacts of n-dodecane and emulsions with a water volume content of 1.98 % , 4.95 % , 9.90 % and 19.80 % have been observed using a high-speed video system. The impact velocity and the target initial temperature have been varied. It is shown that the maximum spreading diameter of the impinging drop, the typical dimensionless diameter of the secondary drops, as well as the number of secondary drops correlate well with the Weber number for a pure liquid. Corresponding scaling relations D max ∼ D 0 We 1 / 2 , D 32 ∼ D 0 We − 1 / 2 and N ∼ We 3 / 2 in the limit We ≫ 1 are derived by considering the dynamics of spreading and breakup. The size of the secondary drops is reduced significantly for high emulsion concentrations. This effect is explained by the stabilizing role of the water drops in the emulsion, whose surface tension is much higher than the surface tension of the bulk liquid.

中文翻译：

---

油包水乳液液滴在薄膜沸腾状态下撞击加热表面的二次雾化

摘要 本研究通过实验研究了油包水乳液液滴撞击热蓝宝石玻璃表面所产生的二次雾化。本研究的主要目的是表征从边缘和薄片破裂中出现的二次液滴。使用高速视频系统观察到正十二烷和水体积含量为 1.98%、4.95%、9.90% 和 19.80% 的乳液的跌落影响。冲击速度和目标初始温度已经改变。结果表明，撞击液滴的最大扩散直径、二次液滴的典型无量纲直径以及二次液滴的数量与纯液体的韦伯数密切相关。对应的缩放关系 D max ∼ D 0 We 1 / 2 , D 32 ∼ D 0 We − 1 / 2 和 N ∼ We 3 / 2 在极限 We ≫ 1 是通过考虑扩散和破裂的动力学推导出来的。对于高乳液浓度，次级液滴的尺寸显着减小。这种效应可以通过乳液中水滴的稳定作用来解释，其表面张力远高于本体液体的表面张力。