The paper investigates the oil–water emulsification process inside a micro-venturi channel. More specifically, the possible influence of Kelvin-Helmholtz instability on the emulsification process. High-speed visualizations were conducted inside a square venturi constriction with throat dimensions of 450 µm by 450 µm, both under visible light and X-Rays. We show that cavity shedding caused by the instability results in the formation of several cavity vortices. Their rotation causes the deformation of the oil stream into a distinct wave-like shape, combined with fragmentation into larger drops due to cavitation bubble collapse. Later on, the cavity collapse further disperses the larger drops into a finer emulsion. Thus, it turns out that the Kelvin-Helmholtz instability is similarly characteristic for hydrodynamic cavitation emulsification inside a microchannel as is the Rayleigh-Taylor instability for acoustically driven emulsion formation.

中文翻译：

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开尔文-亥姆霍兹不稳定性是水动力空化快速高效乳化的关键特征之一


本文研究了微文丘里通道内的油水乳化过程。更具体地说，开尔文-亥姆霍兹不稳定性对乳化过程的可能影响。在可见光和 X 射线下，在喉部尺寸为 450 µm x 450 µm 的方形文丘里管狭窄处进行高速可视化。我们表明，由不稳定性引起的空腔脱落导致了多个空腔涡流的形成。它们的旋转导致油流变形为独特的波浪形状，并由于空化气泡破裂而破碎成更大的液滴。随后，空腔塌陷进一步将较大的液滴分散成更细的乳液。因此，事实证明，开尔文-亥姆霍兹不稳定性与微通道内的水动力空化乳化的特征相似，就像声驱动乳液形成的瑞利-泰勒不稳定性一样。