Bio-Material Transport Pump Activated by Liquid Jet around Single Rising Bubble Chain

证实了上升气泡链的周围存在一个特征流场，该上升气泡链是由单个喷嘴产生的，但呈排状。在精确控制气泡直径和气泡发生频率的情况下，在水池中生成气泡链，观察了气泡链附近这一特征流场的形成过程。作用于气泡链中气泡的升力比作用于单个气泡的升力大，这是由于先导气泡形成的流场所致。认为前导气泡的尾迹导致尾气泡不稳定，特别是气泡形状的变形导致气泡链的弯曲，利用粒子图像测速(PIV)方法对气泡链附近的特征流场进行了可视化。利用动量定理建立了液体射流产生的数学模型。T…在气泡链附近的液体场中引入了控制体积，结果表明，由于液体射流的形成，存在作用于气泡链的特征力。通过与实验结果的对比，对模型的有效性进行了评价。对静止液体中上升的气泡间的流体动力相互作用进行了实验和数值研究。研究表明，气泡雷诺数对垂直上升气泡之间的平衡距离起主导作用。实验也证实了平衡距离的存在。数值模拟表明，随着雷诺数的减小，气泡间的平衡距离减小，两个气泡发生接触，并用显微镜观察了气泡在相互作用下的行为。对得到的图像进行傅里叶描述子，并对气泡形状进行量化。考虑了气泡形状和气泡行为之间的相关性，并对气泡重心位置进行了高精度的评估。当两个气泡碰撞时，气泡形状发生了较大的变形，证实了气泡上升速度发生了很大的变化。从实验和数值上考虑了两个上升气泡之间的流体动力相互作用和合并。结果表明，雷诺数在稳定气泡链的形成中起着重要作用。同时也证实了韦伯数和雷诺数都是重要的参数，特别是粘度的物理性质对于防止气泡合并和气泡链诱导泵的稳定运行都是重要的。较少

It was confirmed that a characteristic flow field existed in surroundings of the rising bubble chain which was row though it was generated from a single nozzle. The bubble chain was generated in the water pool with both the bubble diameter and bubble generation frequency accurately controlled, and the generation process of this characteristic flow field in the neighborhood of the bubble chain was observed. The lift force acting on bubbles in the bubble chain is larger than the one acting on a single bubble, due to the flow field formed by the leading bubbles. It is considered that the wake of the leading bubbles caused the instability of the trailing bubbles, especially the deformation of bubble shape, which resulted in the bent of the bubble chain.The characteristic flow field in the neighborhood of the bubble chain was visualized by PIV (Particle Image Velocimetry) method. The mathematical model of the generation of the liquid jet was also constructed by using the momentum theorem. T … More he control volume was introduced in the liquid field in the neighborhood of the bubble chain and it was shown that there exists the characteristic force acting on the bubble chain due to the liquid jet formation. The validity of the model was evaluated by comparing with the experimental results.The hydrodynamic interaction between a pair of bubbles rising in stagnant liquid was studied both experimentally and numerically. It was understood that the bubble Reynolds number plays the dominant role in the equilibrium distance between a pair of rising bubbles in vertical line. It was also confirmed experimentally that there exists the equilibrium distance. Moreover, it was confirmed numerically that the equilibrium distance decreased and lead to the contact of a pair of bubbles with the decrease in the Reynolds number.The bubble behavior under the interaction was observed with the microscope camera. The Fourier descriptor was used for the obtained image and the bubble shape was quantified. The correlation between the bubble shape and the bubble behavior were considered with a highly accurate evaluation of the bubble center of gravity position. A large deformation of bubble shape was observed when a pair of bubbles collided and it was confirmed that the bubble rising velocity changed greatly.Both the hydrodynamic interaction and the coalescence between a pair of rising bubbles were considered experimentally and numerically. It was clarified that Reynolds number plays the significant role the generation of a steady bubble chain. It was also confirmed that both the Weber and Reynolds numbers are significant parameters, especially the physical property of viscosity is important, both for the prevention of the coalescence of bubbles and for the steady operation of bubble chain induced pump. Less