巷道火灾时期流场及瓦斯浓度变化规律数值模拟研究

Study on numerical simulation of variations of airflow field and gas concentration during roadway fire

为了合理控制巷道入口风速,减少火灾的发生并降低灾害造成的损失,利用Fluent数值模拟软件对某煤矿巷道发生火灾时的流场进行数值模拟研究,探讨了不同的入口风速对火灾的速度场、温度场以及对瓦斯涌出分布的影响。结果表明:入口风速越大,对巷道内风流分布的影响越小,火焰区域速度最低,速度的纵向分布呈现出"圆弧层状"降低分布,并且圆弧顶部不同程度向下凹陷;火灾会引起巷道内瓦斯浓度增大,风速低时瓦斯最高浓度可达到瓦斯爆炸下限,造成瓦斯爆炸;风速的变化,会使"烟流滚退"的距离有较大的改变,且风速越大,巷道内排烟效果越显著。通过分析模拟结果发现,合理控制巷道入口风速对防止瓦斯爆炸和灾后巷道内烟气排放有显著作用。

This paper aims to properly control the inlet air velocity of roadway and reduce the occurrence of fire and its damage in coal mines. Fluent is used to conduct the numerical simulation of airflow in a coal mine roadway in the presence of fire. The effects of different inlet speeds on the velocity field, temperature field and distribution of gas emission are discussed. The results show that the greater inlet air velocity is associated with smaller influence on air flow distribution in the roadway and the lowest air velocity is located in the flame zone.The longitudinal distribution profile of the velocity forms an “arc layered” shape.As fire increases the gas concentration in the roadway, when air velocity is low, the gas concentration can reach the lower limit of gas explosion,causing gas explosion. Changes of air velocity would cause large change in the distance of “smoke flow back”. The greater the air velocity is, the more significant the smoke exhaust effect in the roadway is. The simulation results show that properly control of the inlet air velocity of roadways has a significant effect on preventing gas explosion and smoke emission in the roadway after fire and explosion.