根据多孔介质渗流理论,利用Fluent软件,分别对采空区瓦斯在整个采空区均匀涌出、上邻近层及底板遗煤涌出2种情况下采空区瓦斯分布规律进行了数值模拟。结果表明:采空区瓦斯为上邻近层及底板遗煤处涌出时,沿走向方向,靠近上邻近层及底板处高体积分数瓦斯距离工作面较近;沿竖直方向,瓦斯体积分数分布呈钩状,靠近瓦斯涌出源处瓦斯体积分数最高;整个采空区均匀涌出时采空区瓦斯体积分数分布与上邻近层及底板遗煤涌出时有很大差别。因此,为了得到更符合实际情况的瓦斯分布规律,数值模拟时应按照现场实际的瓦斯涌出源位置建立模型。
The present paper is aimed at introducing a numerical simulation study on the impact of gas emission location on the gas distribution in the goaf. It is for the said purpose,this paper has made a simulation for the distribution regularity of the gas in the goaf under the two different circumstances of the gas emission source locations in accordance with the percolation theory of porous media. As we all know,the location of gas emission has a significant impact on the distribution regularity of the gas in the goaf,in hoping to set a gas emission location as a proper position closer to the actual pouring point than the situation of entire goaf area. In order to make clear the effect of the gas emission source on the gas distribution,firstly,we think it better to work out a 3-d physical model by means of using a Gambit. And,secondly,a software named Fluent has been adopted to simulate the airflow field of the two different kinds of gas emission points,of which the uniform emission from the entire goaf or the upper adjacent layers in addition to the fallen coal around the coal seam. And,finally,we have input the simulated results into the Tecplot software to reach the contours of the gas concentration. Thus,the analysis results help us to get the following conclusions:( 1) The actual location of the gas emission source tends to have little effect on the pressure distribution in the goaf.( 2) When the gas discharges from the entire goaf,it is likely for the high concentration of gas to stay rather far away from the working face,and therefore,the gas concentration may rise from the bottom to the top gradually in the vertical direction to the obvious stratification,as is often the case the gas tends to pour out from the upper adjacent layer by the fallen coal seam nearby. At the same time,the high concentrated gas near the upper adjacent layer and the floor close to the working face in the vertical direction may appear to be of no stratification at all,whereas the gas concentrations near the roof may seem to b