Drop formation in a co-flowing ambient fluid
Drop formation in a co-flowing ambient fluid
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DOI：
10.1016/j.ces.2004.04.006
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发表时间：
2004-08-01
影响因子：
4.7
通讯作者：
Windhab, EJ
中科院分区：
文献类型：
--
作者：
Cramer, C;Fischer, P;Windhab, EJ
通过实验研究层流中毛细管尖端处的液滴形成。分散相通过针注入另一种同向流动的不混溶流体中。有两种不同的液滴形成机制：液滴要么在毛细管尖端附近形成（滴落），要么从延伸的液体喷射中破裂（喷射）。工艺和材料参数对液滴形成的影响取决于破碎机制，并且必须针对每个流域分别进行研究。在这项研究中，我们重点关注滴水。液滴破碎受到分散相和连续相的流动动力学的影响。因此，我们研究了流速、流体粘度和界面张力对液滴尺寸的影响，并观察了卫星液滴生成的动态。尽管通过毛细管将分散流体注入环境流体的基本原理已被广泛研究，但本文的重点是提供全面的实验数据集，以证明该技术作为分散工具的适用性。结果表明，在毛细管尖端形成共流环境液体的液滴代表了一种用于生产单分散液滴的有前途的技术，其中液滴尺寸由连续相的流动强度从外部控制。在从滴落到喷射的转变点，破碎动力学发生显着变化。因此，流域之间的过渡点代表了一个重要的操作点。在本文中，通过研究各种材料和工艺参数对转变点的影响，区分了滴注和喷射。 (C) 2004 Elsevier Ltd. 保留所有权利。
Drop formation at a capillary tip in laminar flow is investigated experimentally. The disperse phase is injected via a needle into another co-flowing immiscible fluid. Two different drop formation mechanisms are distinguished: Either the drops are formed close to the capillary tip-dripping-or they break up from an extended liquid jet-jetting. The effect of the process and material parameters on the drop formation depends on the breakup mechanism and has to be investigated for each flow domain separately. In this study, we focus on dripping. The drop breakup is affected by the flow dynamics of both the disperse and the continuous phase. Consequently, we investigate the effect of flow rates, fluid viscosities and interfacial tension on the droplet size and observe the dynamics of satellite drop generation. Whereas the fundamentals of disperse fluid injection via a capillary into an ambient fluid have been investigated extensively, the focus of this article is on providing a comprehensive experimental data set for proving the applicability of this technique as a dispersing tool. It is shown that drop formation at a capillary tip into a co-flowing ambient liquid represents a promising technique for the production of monodisperse droplets where the droplet size is controlled externally by the flow strength of the continuous phase. The breakup dynamics changes significantly at the transition point from dripping to jetting. Consequently, the transition point between the flow domains represents an important operating point. In this article, dripping is demarcated from jetting by studying the influence of the various material and process parameters on the transition point. (C) 2004 Elsevier Ltd. All rights reserved.