Abstract This study investigates the behaviour of bubble clusters rising amongst single bubbles in a non-Newtonian liquid, employing: a) an ultra-sensitive electrical impedance spectroscopy technique for obtaining void fraction time-series and b) an optical method for estimating cluster size and shape. Bubble clusters cause intense void fraction signal peaks. The novelty concerns the association of signal characteristics with bubble cluster features. Therefore, useful insight on bubble clustering encountered in ultrasound medical applications (such as dissolution of blood clots during thrombosis or cancer drug delivery) is provided. Experiments are performed in co-current, upward bubbly flow. Results show a strong dependence of cluster features on gas superficial velocity (Usg). Void fraction signal analysis demonstrates that peaks become sharper when bubble clusters get larger. On the other hand, time length of signal peaks remains almost constant despite the increase of cluster sizes. Additionally, bubble clusters frequency increases with Usg and decreases with surfactant addition.

中文翻译：

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将空隙率信号与非牛顿液体的并流向上气液流动中的气泡簇特征相关联

摘要 本研究调查了非牛顿液体中气泡簇在单个气泡中上升的行为，采用：a) 超灵敏电阻抗光谱技术获得空隙率时间序列和 b) 估计簇大小的光学方法和形状。气泡簇导致强烈的空隙率信号峰。新颖之处在于信号特征与气泡簇特征的关联。因此，提供了对超声医学应用中遇到的气泡聚类的有用见解（例如血栓形成或癌症药物输送过程中血块的溶解）。实验在并流、向上的气泡流中进行。结果表明簇特征对气体表观速度（Usg）有很强的依赖性。空隙分数信号分析表明，当气泡簇变大时，峰变得更尖锐。另一方面，尽管簇大小增加，但信号峰值的时间长度几乎保持不变。此外，气泡簇频率随着 Usg 增加而增加，随着表面活性剂的加入而减少。