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

证实了单喷嘴产生的上升气泡链在其周围存在一个特征流场。在精确控制气泡直径和气泡产生频率的情况下，在水池中产生气泡链，并观察气泡链附近特征流场的产生过程。由于前导气泡形成的流场，作用在气泡链中的气泡上的升力比作用在单个气泡上的升力大。认为前导气泡的尾迹引起后导气泡的不稳定，特别是气泡形状的变形，导致气泡链的弯曲。采用PIV （Particle Image velocity）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。进一步在气泡链附近的液体场中引入了控制体积，并证明了由于液体射流的形成而存在作用于气泡链上的特征性力。通过与实验结果的比较，对模型的有效性进行了评价。采用实验和数值方法研究了滞流液体中一对气泡之间的水动力相互作用。据了解，气泡雷诺数在一对垂直上升气泡之间的平衡距离中起主导作用。实验还证实了平衡距离的存在。数值证实了随着雷诺数的减小，平衡距离减小，导致一对气泡接触。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符，并对气泡形状进行量化。考虑了气泡形状与气泡行为之间的相关性，并对气泡重心位置进行了高度精确的评估。当一对气泡碰撞时，观察到气泡形状发生了较大的变形，并证实气泡上升速度发生了较大的变化。在实验和数值上考虑了水动力相互作用和一对上升气泡之间的聚并。阐明了雷诺数对稳定气泡链的产生起着重要作用。研究还证实了韦伯数和雷诺数是防止气泡聚结和保证气泡链诱导泵稳定运行的重要参数，其中粘度的物理性质尤为重要。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