地下水曝气空气流动形态影响因素数值模拟

Numerical analysis of factors influencing air flow pattern during air sparging

在阐明地下水曝气修复机理控制方程的基础上,对某污染场地地下水曝气修复中不同参数对气体流动形态的影响规律进行了数值模拟研究.结果表明:土体固有渗透率对曝气影响半径和分布形态有显著的影响,影响半径随土体固有渗透率的增大而减小;增加空气注入流量,曝气影响半径略有增大.当形成稳定流动形态后,再增加空气注入流量,曝气法影响半径提高有限;曝气影响半径基本不受地下水位线以下曝气井深度影响.实际工程中,曝气井位置应根据污染场地有机污染物分布深度确定;地下水流动对曝气井上游气体运移有抑制作用,对下游气体运动有放大作用,因此曝气法下游区域空气影响半径大于上游.

Based on the introduction of the governing equations of gas water two-phase flow during air sparging,the influence of different parameters on the air flow pattern in some contaminated site was studied through numerical analysis.The research results are as follows.The intrinsic permeability of soil has great influence on the radius of influence（ROI） and air distribution.ROI decreases with the increase of the soil permeability.As the flow rate of air is raised,ROI will increase a little.Once the stable flow pattern is formed,more flow rate will contribute little to the increase of ROI.The depth of air sparging well under the water table almost has no effect on ROI,therefore position of the well should be mainly determined by the depth of contamination scope.In addition,the air transportation is limited in upper reaches but enhanced in lower reaches,so the ROI of lower reaches is higher than that of upper reaches.