Hydraulic Criteria of a Bubble-Pump System for Destratification

由于热分层作用下的垂向交换，人工储层深层经常出现低浓度氧。低氧水团加速泥质层微孔中磷的再次溶解，导致储层水的熵化。探索了利用大尺度气泡对水体进行分层的可行技术方法。一个大的、单一的气泡的形状是在表面上是球形的，底部几乎是平的。用释放的风量来解释上升速度，用势理论预测的上升速度与实验结果吻合较好。由类似旋涡环的结构产生的循环区将周围的流体带入气泡的尾流区，然后向上输送。据观察，单个气泡所输送的体积约为气泡体积的25倍。在第二阶段，分析了采用圆筒的气泡泵系统。圆柱体中的垂直速度是向上的，与气泡的上升速度一致。但当气泡离开圆筒顶部后，垂直速度减小并变为向下。在速度方向发生变化之前释放下一个气泡时，效率最高。理论上估计了圆柱内垂直速度随时间的变化，与实验结果吻合较好。升力较重的水扩散的水平尺度被解释为圆柱体出口的密度弗劳德数和圆柱体的淹没的函数。在圆柱出口上方设置缓冲板，可以有效地改变上升负浮力射流的方向，但对于提高较深水体的抽速效率效果较差。

Low concentrain of oxygen frequently appears in a deep layer of a man-made reservoir due to search vertical exchange under thermal stratification. Low oxygen water mass accelerates phosphorus in micro pores of muddy bed to resolute again and then results in entrophication of reservoir water. Feasible technical methods are sought for destratification of water body on use of a large scale air-bubble.Shape of a large, single bubble is spherical in the upper surface and the bottom is nearly flat. The rising velocity is explained in terms of air volume released and the prediction through a potential theory agreed well with experimental results. A circulation zone generated by a structure similar to a vortex ring entrains surrounding fluid into the wake zone of a bubble and then transport it upward. Transported volume by a single bubble is observed to be about 25 times of the volume of a bubble.In a second phase a bubble-pump system used a cylinder is analyzed. The vertical velocity in a cylinder is upward in accordance with the rise of a bubble. But after a bubble leaves the top of a cylinder, the vertical velocity reduces and turns into downward. The highest efficiency is obtained when a next bubble is released just before this change in the direction of velocity takes place. Time variation of the vertical velocity in a cylinder is theoretically estimated with good accordance with experimental results. The horizontal scale of the spreading of lifted heavier water is explained as a function of the densimetric Froude number at the outlet of a cylinder and the submergence of a cylinder. A buffl plate set above an outlet of a cylinder is effective to change the direction of a rising negative buoyant jet but has scarse effect in gaining better efficiency of the pumping rate of a deeper water body.