Experimental analysis of smoke dispersion in belt fires by using a real-size model of the underground space

It is essential to investigate the dispersion of a large amount of toxic and harmful smoke in coal mine network during belt fires. A real-size model of an underground space was used to study the additional thermal resistance of single roadway and the dispersion characteristics of CO in bending structure, as well as the effect of air velocity on CO dispersion. The results show that the resistance of high temperature air flow is related to the ventilation resistance of the roadway under normal airflow, and is proportional to airflow temperature. The additional thermal resistance increases first and then decreases with time, and curve trend is similar to multiple "humps" with the increase of distance, which indicates that temperature is dominant factor. The distribution of CO is V-shaped at 90 degrees corner, and the distribution pattern is unaffected by corner number. The increase of the air velocity destroys the CO distribution at the initial corner, and the air vortex zone appears at the bottom of the roadway. Meanwhile, the smoke flow diffused to the working face shifts from the outer wall to the inner wall of the working face. The results are helpful for selecting emergency evacuation areas and implementing safe measures.