工作面通风方式对采空区风流流场和瓦斯运移的影响

Effects of the mining-face ventilation mode on the air-current field as well as the gas movement in the gob

工作面采用的通风方式对采空区流场和瓦斯运移有很大的影响。对工作面采用上、下行通风方式的采空区风流流场和瓦斯分布进行了数值模拟。结果表明:在煤层倾角不同时,工作面采用不同的通风方式下,采空区的漏风量、风流流场和瓦斯运移情况有很大差别。上行通风时漏风量随煤层倾角增大而增高。当下行通风工作面通风压力小于采空区自然风压时会发生采空区气体倒流现象,漏风量随煤层倾角增大而增高。上行通风采空区漏风量比下行通风大;下行通风工作面采空区瓦斯总量大于上行通风。随着煤层倾角增加,上行通风和下行通风采空区瓦斯总量都减小。

The present paper intends to introduce our research results of the effect of the mining-face ventilation mode on the air-current field as well as the gas migration in the gob. For our research pur- pose, we have first of all worked out a numerical simulation of the airflow field and the gas distribution situation in it. The results of our investigation demonstrate that there is a dominant difference in the air leakage, air-current flow and its movement because the seam obliqui- ty and ventilation mode of the working face are quite different. The gob gas buoyancy pressure caused by the natural ventilation pressure and the total pressure of the ventilator across the face decide the＇ amount of the gob and its air leakage distribution. In case of the as- cending ventilation, the total pressure of the ventilator across the face and the spontaneous air pressure are in the same direction, hence, the greater the pressure difference across the face, the greater the amount of air leakage. Air linkage went into the gob from the lower comer of the face and the lower face, while air leakage of gas carried went into the face from the upper comer upper face. However, when the pressure of the face comes from the descending ventilation, the pressure of the face would be weaker than the natural pressure in the gob, for the natural air pressure, the ventilation pressure and the to- tal pressure of the ventilator across the face are going on in the oppo- site directions. In that case, there would occur the gas reflux and the air leakage in the gob from the comer or the lower part of the working face, and, naturally, the gas produced would flow into the working face from the upper comer and the upper part. On the contrary, when the descending ventilation comes to turn, the natural ventilation pressure and the face pressure would come in the opposite directions. And, now, even at the same condition, the air-leaking rate in the as- cending ventilation of the gob would be greater than that in the de- scending ventilation, and vice versa. In such a case, with the coal seam angle increased, the gas volume would be falling whether in as- cending ventilation or in the descending ventilation.