为研究煤矿井下巷道火灾动态密闭过程中烟气特性变化规律，通过FDS软件对矿井巷道火灾进行全尺寸数值模拟；利用缩尺实验建立了巷道火灾CO体积分数衰减速率模型，研究2、3、4 MW火源功率下，巷道在50%至100%的密闭过程中横向、纵向温度分布及烟气蔓延规律；并建立巷道完全密闭后CO体积分数衰减模型，预测火灾熄灭时间。结果表明：密闭比例由50%至100%的变化过程中，顶棚中心温度先急剧下降后缓慢升高；密闭后火源上方温度呈上高下低的分布状态，且距离火源越近温度衰减速率越快；顶棚温度纵向分布出现整体升高现象，最高温度点向密闭侧偏移1~3 m；烟气在密闭侧沉积现象明显，分层现象消失；单侧完全密闭后，CO体积分数与时间呈线性关系，通过CO体积分数衰减速率模型预测2、3、4 MW火源功率下的火源分别于103.16、94.40、86.21 s后熄灭。

In order to study the change law of smoke characteristics in the dynamic sealing process of coal mine roadway fire, FDS software was used to conduct full-scale numerical simulation of mine roadway fire, and the CO volume fraction decay rate model of roadway fire was established by scale experiment. The transverse and longitudinal temperature distribution and smoke spread law in the sealing process of 50% to 100% of the roadway were established, and the CO volume fraction attenuation model was established to predict the fire extinguishing time after the roadway was completely sealed. The results show that during the change of sealing ratio from 50% to 100%, the temperature at the center of the ceiling first sharply decreases and then slowly increases; after being sealed, the temperature above the fire source shows a distribution pattern of high temperature above and low temperature below, and the closer it is to the fire source, the faster the temperature decay rate; the vertical distribution of ceiling temperature shows an overall increase, the maximum temperature point shifts 1-3 m to the sealed side; the deposition phenomenon of smoke on the sealed side is obvious, and the stratification phenomenon disappears; the relationship between CO volume fraction and time is linear when one side is completely sealed. According to the CO volume fraction decay rate model, it is predicted that the ignition source of 2, 3 and 4 MW is extinguished after 103.16, 94.40 and 86.21 s, respectively.