矿井巷道火灾烟流逆退数值模拟及临界风速研究

为了研究矿井发生火灾后高温烟流的蔓延规律及影响因素，利用COMSOL软件对火区进行数值模拟，建立巷道三维模型，得到火区风流速度与温度分布。通过改变边界条件，分析火风压作用下，火区烟气在不同控制风速、巷道条件作用下蔓延规律，得出不同因素与临界风速的关系，为选取合理的火灾控制风速提供理论依据。研究结果表明:火源温度一定时，巷道入口风速越低，火源下风侧高温烟流越靠近巷道顶部，随着风速增大，向巷道下部蔓延；风速较低时，在火区火风压的作用下，会产生烟流逆退现象，随着风速的增大，逆流层长度和厚度随之减小；巷道入口通风条件不变时，火区温度越高越容易产生烟流的逆退，影响范围越大；巷道高度越高、上行风坡度越小，越易发生逆退现象；不同影响因素与巷道平均温度不成正比关系，其中下行风坡度5~15°时巷道平均温度较高且易于发生烟流滚退现象，影响范围较大；火源温度、巷道条件与临界风速的数据拟合结果对预测巷道的临界风速有较好的参考价值。

Study on numerical simulation of smoke backflow and critical wind speed in mine roadway fire

In order to study the spread laws and influence factors of high temperature smoke flow after the mine fire,the COMSOL software was used to conduct the numerical simulation.A three dimensional model of roadway was established,and the wind flow velocity and temperature distribution in the fire area were obtained.By changing the boundary conditions,the spread laws of smoke in the fire area under different control wind speeds and roadway conditions with the effect of fire wind pressure were analyzed,then the relationship between different factors and the critical wind speed was obtained,which provided theoretical basis for selecting the reasonable fire control wind speed.The results showed that when the fire source temperature was constant,the lower the wind speed at the entry of roadway,the closer the high temperature smoke flow on the downwind side of fire source to the roadway top.As the wind speed increased,the smoke spread to the lower part of roadway.When the wind speed was low,the phenomenon of smoke backflow would occur under the effect of fire wind pressure in the fire area,and with the increase of wind speed,the length and thickness of countercurrent layer decreased accordingly.When the ventilation conditions at the roadway entrance remained unchanged,the higher the temperature in the fire area,the more likely the occurrence of smoke backflow,and the larger the influence range.The higher the roadway height and the greater the upward wind slope,the more likely the occurrence of smoke backflow.Different influencing factors were not in direct proportion to the average temperature of the roadway.When the downward wind slope was 5~15°,the average temperature of roadway was high and the smoke flow was prone to roll back,and the influence range was larger.The fitting results of fire source temperature,tunnel conditions and critical wind speed have good reference value for predicting the critical wind speed of roadway.