Dynamics of bubble formation in highly viscous liquids.
Dynamics of bubble formation in highly viscous liquids.
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DOI：
10.1021/la703849x
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发表时间：
2008-03
期刊：
影响因子：
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通讯作者：
K. Pancholi;E. Stride;M. Edirisinghe
中科院分区：
文献类型：
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作者：
K. Pancholi;E. Stride;M. Edirisinghe
最近，人们对用于制备用作超声造影剂和药物递送载体的单分散微泡悬浮液的装置的开发产生了相当大的兴趣。这些应用不仅需要高度的气泡均匀性，而且还需要8 μ m的最大气泡尺寸，并且这为开发对给定装置中气泡形成过程的改进理解提供了强烈的动机。这项工作的目的是调查气泡形成的T型接头设备，并确定不同的工艺参数后气泡的大小，特别是液体粘度的影响。使用高速照相机记录在特别设计的T形接头中气泡形成的图像，用于不同的液体与气体流速比（Ql/Qg）和不同的液体粘度（微升）。有人发现，在焦点区域的流动剖面的轴对称斯托克斯流的分析的基础上的理论预测准确到6%以内时，与实验数据相比，这表明，这提供了一个合适的手段来描述气泡的形成过程。理论和实验结果均表明，Ql/Qg和穆尔对气泡的形成和最终尺寸有显著影响，较高的流速和较高的粘度产生较小的气泡。然而，发现存在Ql/Qg和穆尔的极限值，超过该极限值，气泡尺寸不会进一步减小。
There has recently been considerable interest in the development of devices for the preparation of monodisperse microbubble suspensions for use as ultrasound contrast agents and drug delivery vehicles. These applications require not only a high degree of bubble uniformity but also a maximum bubble size of 8 mum, and this provides a strong motivation for developing an improved understanding of the process of bubble formation in a given device. The aim of this work was to investigate bubble formation in a T-junction device and determine the influence of the different processing parameters upon bubble size, in particular, liquid viscosity. Images of air bubble formation in a specially designed T-junction were recorded using a high-speed camera for different ratios of liquid to gas flow rate (Ql/Qg) and different liquid viscosities (microl). It was found that theoretical predictions of the flow profile in the focal region based on analysis of axisymmetric Stokes flow were accurate to within 6% when compared with the experimental data, indicating that this provided a suitable means of describing the bubble formation process. Both the theoretical and experimental results showed that Ql/Qg and mul had a significant influence upon bubble formation and eventual size, with higher flow rates and higher viscosities producing smaller bubbles. There were, however, found to be limiting values of Ql/Qg and mul beyond which no further reduction in bubble size was achieved.