Experimental and Numerical Investigation of Single Bubble Dynamics in a Two-Phase Bubbly Medium
Experimental and Numerical Investigation of Single Bubble Dynamics in a Two-Phase Bubbly Medium
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DOI：
10.1115/1.4005424
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发表时间：
2011-12
影响因子：
2
通讯作者：
Arvind Jayaprakash;Sowmitra Singh;G. Chahine
中科院分区：
文献类型：
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作者：
Arvind Jayaprakash;Sowmitra Singh;G. Chahine
本文通过实验研究了稀气泡水-空气混合物中气泡的动力学，并将实验结果与简单的均匀可压缩流体模型进行了比较，以阐明更先进的数值解的要求。实验的目的是为我们正在开发的先进气泡流动数值模型提供输入和验证。在两相流建模中，单个气泡的动力学是基于液体或等效均匀介质中的球形孤立气泡动力学，对这些经典方法进行了修正。主/初级气泡是由充电电容器的水下火花放电产生的，而气泡介质是通过电解产生的。主气泡的大小由放电电压、电容器尺寸和容器内的环境压力控制。细气泡的大小和浓度由电解电压、导线的长度、直径、排列和类型以及容器内施加的压力控制。这样就可以对控制初级气泡动力学的因素进行参数化研究，并开发初级气泡特征量（如最大气泡半径和气泡周期）与周围两相介质特征（微气泡尺寸和空隙率）之间的关系。用高速视频摄影观察了主气泡和混合物的动力学。通过对高速电影图像的分析，推导出气泡混合物在流体域中的空隙率，并得到其与时间和空间的函数关系。利用现场压力测量和高速摄像分析了主气泡与气泡介质之间的相互作用。对一次气泡能量、气泡混合密度（孔隙率）等参数的变化进行了研究。然后将实验数据与一个简单的可压缩流体介质模型进行比较，该模型考虑了介质性质在空间和时间上的变化。这有助于说明这些简单模型在哪些地方是有效的，哪些地方需要改进。这些信息对于欧拉-拉格朗日代码的并行开发是有价值的，该代码解释了场中气泡的动力学及其相互作用。
The dynamics of a bubble in a dilute bubbly water-air mixture is investigated experimentally and the results compared with a simple homogeneous compressible fluid model in order to elucidate the requirements from a better advanced numerical solution. The experiments are conducted in view of providing input and validation for an advanced bubbly flow numerical model we are developing. Corrections for classical approaches where in the two-phase flow modeling the dynamics of individual bubble is based on spherical isolated bubble dynamics in the liquid or an equivalent homogeneous medium are sought. The main/primary bubble is produced by an underwater spark discharge from charged capacitors, while the bubbly medium is generated using electrolysis. The size of the main bubble is controlled by the discharge voltage, the capacitors size, and the ambient pressure in the container. The size and concentration of the fine bubbles is controlled by the electrolysis voltage, the length, diameter, arrangement, and type of the wires, and also by the pressure imposed in the container. This enables parametric study of the factors controlling the dynamics of the primary bubble and development of relationships between the primary bubble characteristic quantities such as achieved maximum bubble radius and bubble period and the characteristics of the surrounding two-phase medium: micro bubble sizes and void fraction. The dynamics of the main bubble and of the mixture is observed using high speed video photography. The void fraction of the bubbly mixture in the fluid domain is deduced from image analysis of the high speed movies and obtained as a function of time and space. The interaction between the primary bubble and the bubbly medium is analyzed using both field pressure measurements and high-speed videography. Parameters such as the primary bubble energy and the bubble mixture density (void fraction) are varied, and their effects studied. The experimental data is then compared to a simple compressible fluid medium model which accounts for the change in the medium properties in space and time. This helps illustrate where such simple models are valid and where they need improvements. This information is valuable for the parallel development of an Eulerian-Lagrangian code, which accounts for the dynamics of bubbles in the field and their interaction.