斜坡地形CO2扩散规律相似试验研究

基于相似性原理,在不同坡度(0°、20°、30°、45°)及不同地面粗糙度(木质地面、土质地面)条件下进行了小尺寸的CO2泄漏试验,研究坡度和地面粗糙度对CO2泄漏扩散的影响,为全尺寸现场CO2泄漏试验提供参考。结果表明:坡度的存在对CO2扩散产生了较为明显的影响,坡度越大,斜坡上体积分数梯度越大,坡度小于20°时,对CO2扩散影响几乎无影响,坡度大于30°时,影响开始凸显;与无坡度的平面扩散相比,斜坡下方出现明显的CO2聚集区域,坡度越大,聚集现象越明显,体积分数分布越平均;地面粗糙度的增加使整体CO2体积分数有明显的上升,泄漏口附近(0.25 m)体积分数上升最为明显,整个泄漏场浓度分布更加平均,浓度梯度更小;此外,地面粗糙度的增加一定程度上抑制了泄漏过程的卷吸效应。

Similarity examination of the CO2 diffusion regularity of the slope topography

The present paper aims at studying the effect of the slope and/or the ground roughness on the CO2 leakage and diffusion.Based on the principle of similarity,we can test and work out 6 kinds of CO2 flowing leakage rate designed under the 4 different slopes(0°,20°,30°,45°)and 2 different ground roughness conditions(e.g.the wooden ground and the earthen ground).The slope has been adjusted by setting the different platform heights and the ground medium conditions in the fullscale experimental areas by laying 3 cm dry plateau loess layer on,if the slope existence had a significant impact on the diffusion of the CO2.On the other hand,if the slope were less than20°,there would hardly be any impact on the influence of CO2 diffusion.What is more,if the slope were to be greater than 30°degrees,the effect would begin to be noticeable.In such a situation,the CO2 concentration clustering area would appear below the slope as compared with the plane diffusion area with no slope.And,then,the steeper the slope,the more noticeable the aggregation phenomenon and the more average the volume fraction would be distributed.The increase in the ground roughness may bring about inconsistent effect on the CO2 leakage at the different flowing rates.For instance,when the leakage flowing frequency is 5 L/min near the leakage point,the volume fraction under the soil surface conditions would become higher than the volume fraction under the wooden ground conditions,though the volume fraction were to be relatively lower in the far field.Nevertheless,if the leakage rate becomes greater than or equal to 10 L/min,the CO2 volume fraction of each measuring point under the earth ground conditions would have a significant increase as compared with those of the wooden ground,so that the CO2 volume fraction distribution of the entire leakage area become more even,with the volume fraction gradient being smaller.In addition,the increase of the ground roughness may in turn prohibit the entrainment effect of the leakage process to some extent.And,if it were in case of the wooden ground,the volume fraction at measuring point No.1 should or may decrease with the increase of the flowing rate.Nevertheless,in the case of the earth ground,the volume fraction at No.1 measuring point would be increasing with the increase of the flowing rate.