Comparison of Bubble Size Distributions Inferred from Acoustic, Optical Visualisation, and Laser Diffraction
Comparison of Bubble Size Distributions Inferred from Acoustic, Optical Visualisation, and Laser Diffraction
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DOI：
10.3390/colloids3040065
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发表时间：
2019-12-01
影响因子：
2.4
通讯作者：
Zimmerman, William B.
中科院分区：
文献类型：
--
作者：
Desai, Pratik D.;Ng, Woon Choon;Zimmerman, William B.
气泡测量已在文献中广泛讨论，并且已广泛进行比较研究以验证各种形式的气泡尺寸推断所获得的结果。本文探讨了用于获取气泡云气泡尺寸分布的三种方法：光学检测、激光衍射和声学推断。这些方法中的每一种都因其固有的推理方法或由于缺乏测量特异性而存在设计缺陷而各有优点和缺点。清楚地表明，看到气泡和听到气泡在数量上有本质上的不同。正在测试的主要假设是，对于气泡云，与其他技术相比，声学方法能够检测到较小的气泡，因为声学测量取决于气泡的固有特性，而光子学和光学方法无法“看到”较大气泡后面的较小气泡。声学方法提供气泡云的实时尺寸分布，而对于其他技术，必须进行适当的调整或妥协才能获得可靠的数据。声学气泡光谱法始终记录其他技术未检测到的较小气泡。声学方法和光学方法的差异最大，平均气泡尺寸的尺寸差异范围为 5-79%。激光衍射法和光学方法之间的尺寸差异为 5-68%。激光衍射和声学方法之间的差异较小，范围在 0%（即一致）到 49% 之间。光学方法、激光衍射和声学方法之间观察到较大差异，而激光衍射和声学方法之间具有良好的一致性。激光衍射和声学方法之间的显着差异（35％和49％）证明了这一假设，因为在这些测量中较小气泡的比例较高（即，在通过激光衍射测量期间较小的气泡“隐藏”）。这项研究表明，声学气泡光谱法能够检测比激光衍射和光学技术更小的气泡。传热传质研究证明了这一点，该研究表明，与细气泡相比，微气泡的界面面积增加，从而提高了性能。
Bubble measurement has been widely discussed in the literature and comparison studies have been widely performed to validate the results obtained for various forms of bubble size inferences. This paper explores three methods used to obtain a bubble size distribution-optical detection, laser diffraction and acoustic inferences-for a bubble cloud. Each of these methods has advantages and disadvantages due to their intrinsic inference methodology or design flaws due to lack of specificity in measurement. It is clearly demonstrated that seeing bubbles and hearing them are substantially and quantitatively different. The main hypothesis being tested is that for a bubble cloud, acoustic methods are able to detect smaller bubbles compared to the other techniques, as acoustic measurements depend on an intrinsic bubble property, whereas photonics and optical methods are unable to "see" a smaller bubble that is behind a larger bubble. Acoustic methods provide a real-time size distribution for a bubble cloud, whereas for other techniques, appropriate adjustments or compromises must be made in order to arrive at robust data. Acoustic bubble spectrometry consistently records smaller bubbles that were not detected by the other techniques. The difference is largest for acoustic methods and optical methods, with size differences ranging from 5-79% in average bubble size. Differences in size between laser diffraction and optical methods ranged from 5-68%. The differences between laser diffraction and acoustic methods are less, and range between 0% (i.e., in agreement) up to 49%. There is a wider difference observed between the optical method, laser diffraction and acoustic methods whilst good agreement between laser diffraction and acoustic methods. The significant disagreement between laser diffraction and acoustic method (35% and 49%) demonstrates the hypothesis, as there is a higher proportion of smaller bubbles in these measurements (i.e., the smaller bubbles 'hide' during measurement via laser diffraction). This study, which shows that acoustic bubble spectrometry is able to detect smaller bubbles than laser diffraction and optical techniques. This is supported by heat and mass transfer studies that show enhanced performance due to increased interfacial area of microbubbles, compared to fine bubbles.