Based on the one-step microfluidic method of producing hollow droplet with thin film, this article studies the effect of water and oil flow rate, gas pressure, and viscosity of aqueous phase on the dynamic formation and size of hollow droplet by analyzing large amounts of data acquired automatically. The results show that the filling stage of hollow droplet is similar to that of microbubble formation, while the necking stage is similar to that of droplet formation process. Furthermore, based on the data and mathematical model describing droplet formation mechanism, a filling stage model including Capillary number of continuous phase is developed. Considering the dynamic interface breakup and displacement of droplet in necking stage, a necking stage model is developed. The results show that the model results considering filling and necking stage fit well with the experimental data, and the relative error is less than 5%. Finally, the same model with parameters is used to predict the size of hollow droplet with other systems and devices, and the model is proved to be relative precise in our experimental conditions. The results presented in this work provide a more in-depth understanding of the dynamic formation and scaling law of hollow droplet with G/L/L systems in microfluidic devices. © 2017 American Institute of Chemical Engineers AIChE J, 2017

中文翻译：

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双同轴微流控装置中气/油/水系统中空滴的动态形成与结垢规律

基于一步法生产薄膜的中空液滴的方法，本文通过分析大量的水和油，研究了水和油的流速，气压和水相粘度对中空液滴动态形成和尺寸的影响。数据自动获取。结果表明，空心液滴的填充阶段与微泡形成相似，而颈缩阶段与液滴形成过程相似。此外，基于描述液滴形成机理的数据和数学模型，开发了包括连续相的毛细管数的填充阶段模型。考虑到颈缩阶段的动态界面破裂和液滴位移，建立了颈缩阶段模型。结果表明，考虑填充和缩颈阶段的模型结果与实验数据吻合良好，相对误差小于5％。最后，使用带有参数的相同模型来预测其他系统和设备中空心液滴的大小，并且该模型在我们的实验条件下被证明是相对精确的。这项工作中提供的结果提供了更深入的了解微流体设备中G / L / L系统的空心液滴的动态形成和结垢定律。©2017美国化学工程师学会 这项工作中提供的结果提供了更深入的了解微流控设备中G / L / L系统的空心液滴的动态形成和结垢定律。©2017美国化学工程师学会 这项工作中提供的结果提供了更深入的了解微流控设备中G / L / L系统的空心液滴的动态形成和结垢定律。©2017美国化学工程师学会AIChE的Ĵ，2017年