Hydraulic Criteria of a Bubble-Pump System for Destratification

在热力层结作用下寻找垂向交换，在人造油藏深层经常出现低浓度氧气雨。低氧水体加速泥质层微孔隙中磷的再溶解，导致水库水的富营养化。探索了利用大型气泡进行水体分层的可行技术方法，即上表面大而单一的气泡形状为球形，底部近于平坦。上升速度用释放的风量来解释，用势理论预测的结果与实验结果符合得很好。由类似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，然后将其向上输送。观察到单个气泡输送的体积约为气泡体积的25倍。在第二阶段中，分析了采用圆柱体的气泡泵系统。圆柱体中的垂直速度随着气泡的上升而上升。但气泡离开圆柱体顶部后，垂直速度降低，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。从理论上估算了圆柱体内垂直速度的时间变化，与实验结果吻合较好。将提升的较重水扩散的水平尺度解释为圆柱体出口处的密度弗劳德数和圆柱体的淹没程度的函数。设置在圆柱体出口上方的缓冲板可以有效地改变上升的负浮力射流的方向，但在较深水体的抽水效率方面效果较差。

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.