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

实验结果表明，虽然单喷嘴产生的气泡链呈列状，但气泡链周围存在一个特征流场。通过精确控制气泡直径和气泡产生频率，在水池中产生气泡链，观察气泡链附近特征流场的产生过程。作用在气泡链中气泡上的升力大于作用在单个气泡上的升力，这是由于领先气泡形成的流场。研究认为，尾流中的尾流引起了尾流中气泡的不稳定性，特别是气泡形状的变形，导致了气泡链的弯曲，并利用PIV（Particle Image Velocimetry）技术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。不 关于我们 在气泡链附近的液场中引入控制体积，表明由于液体射流的形成，气泡链上存在特征力。通过与实验结果的比较，验证了模型的有效性。对静止液体中上升气泡间的相互作用进行了实验研究和数值模拟。研究表明，气泡雷诺数对垂直上升气泡间的平衡距离起主导作用。实验还证实了存在平衡距离。数值模拟结果表明，随着雷诺数的减小，气泡间的平衡距离逐渐减小，气泡间的相互接触也随之发生，并利用显微摄像机观察了气泡在相互作用下的行为。将傅立叶描述符用于所获得的图像，并量化气泡形状。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精度的评估。通过实验和数值模拟，研究了两个气泡碰撞时气泡形状的变化，并证实了气泡上升速度的变化。结果表明，雷诺数对稳定气泡链的形成起着重要的作用。实验还证实，Weber数和Reynolds数都是重要的参数，特别是粘度的物理性质，对于防止气泡的聚并和气泡链诱导泵的稳定运行都是重要的。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