Centrifuge modeling of air sparging - a study of air flow through saturated porous media.
Centrifuge modeling of air sparging - a study of air flow through saturated porous media.
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DOI：
10.1016/s0304-3894(99)00140-5
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发表时间：
2000-02
影响因子：
13.6
通讯作者：
Catalina Marulanda;Patricia J. Culligan;J. Germaine
中科院分区：
文献类型：
--
作者：
Catalina Marulanda;Patricia J. Culligan;J. Germaine
空气喷射作为处理受污染含水层的一种补救技术，其成功之处已有充分的文献记载。然而，迄今为止，在控制注入空气通过饱和地面的流动的机制上没有达成共识。目前，只有实验室实验的定性结果可用于预测喷射井的影响区。考虑到通过土壤的气流模式将最终决定空气喷射处理的效率，重要的是量化喷射空气如何通过饱和多孔介质。本研究的主要目的是发展一个模型，描述通过饱和多孔介质的空气传输。本文介绍了一个正在进行的研究，采用离心建模再现原位空气喷射条件的结果。压力测试是一种实验技术，允许在实验室中缩小规模复制现场遇到的应力和压力分布。现场条件对实际气流模式的发展至关重要。实验是在透明多孔介质中进行的，该介质由浸没在折射率匹配的流体中的破碎硼硅酸盐玻璃组成。当空气以变化的重力加速度流过多孔介质时，观察到空气。记录的实验图像允许确定的流动模式，突破速度，和羽流形状的g-水平和注射压力的函数。结果表明，空气流动模式不同，从指法，在低g-水平，在较高的加速度脉冲。多孔介质的颗粒和孔径分布并不完全控制空气流动特性。喷嘴几何形状对突破速度和空气羽流形状有一定的影响。已经进行了实验，以比较空气流过饱和多孔介质的速度与空气在纯液体中的速度。结果表明，空气通过介质的速度低于纯流体中的速度，正如预期的那样。然而，在高g水平下，羽流突破速度与纯流体中的空气速度成比例。
The success of air sparging as a remedial technology for treatment of contaminated aquifers is well documented. However, there is no consensus, to date, on the mechanisms that control the flow of injected air through the saturated ground. Currently, only qualitative results from laboratory experiments are available to predict the zone of influence of a sparging well. Given that the patterns of air flow through the soil will ultimately determine the efficiency of an air sparging treatment, it is important to quantify how sparged air travels through a saturated porous medium. The main objective of this research is to develop a model that describes air transport through saturated porous media. This paper presents results from an ongoing study that employs centrifuge modeling to reproduce in situ air sparging conditions. Centrifuge testing is an experimental technique that allows reduced-scale duplication, in the laboratory, of the stresses and pressure distributions encountered in the field. In situ conditions are critical in the development of actual air flow patterns. Experiments are being conducted in a transparent porous medium consisting of crushed borosilicate glass submerged in fluids of matching indices of refraction. Air is observed as it flows through the porous medium at varying gravitational accelerations. Recorded images of experiments allow the determination of flow patterns, breakthrough velocities, and plume shapes as a function of g-level and injection pressure. Results show that air flow patterns vary from fingering, at low g-levels, to pulsing at higher accelerations. Grain and pore size distribution of the porous medium do not exclusively control air flow characteristics. Injector geometry has a definite effect on breakthrough velocities and air plume shapes. Experiments have been conducted to compare the velocity of air flow through the saturated porous medium to that of air in pure liquids. Results show that the velocity of air through the medium is lower than that in the pure fluid, as expected. At high g-levels however, plume breakthrough velocities are proportional to the velocity of the air in the pure fluid.