Numerical simulation of smoke spread characteristics and emergency escape at different scales under the interaction of ventilation and thermal driving force in mine with complex ventilation network

In mines with intricate ventilation systems, effectively preventing, controlling, and rescuing conveyor belt fires present significant challenges. This study aims to explore the laws of airflow disturbance, heat transfer, and smoke diffusion in different scales (field-area-network). The objective is to develop a theory that explains fire stepwise evolution due to the interaction between ventilation and thermal driving force. A multi-scene, cross-scale strategy for controlling fire smoke is proposed, along with an approach to determine optimal escape routes for workers in the event of a fire. A complex 3D dynamic model is established to validate the effectiveness of this strategy, while the Ventfire module (Chasm Ventsim) is employed to simulate three fire scenarios and analyze the dynamic characteristics of smoke propagation during a disaster. The results indicate that the temperature of high-temperature smoke is more susceptible to the scale effect rather than the air quantity. As the smoke moves away from the fire source, its temperature rapidly decreases, converging with the airflow temperature. However, the air quantity significantly impacts the maximum smoke temperature at the fire source. The concentration of carbon monoxide (CO) and visibility follow a pattern similar to that of the development of the fire. During emergency evacuations, the length of escape routes increases by 1.5 times due to increased smoke concentrations and reduced visibility. By implementing strategies for smoke prevention and exhaust, alongside the design of well-planned escape routes, the efficiency of evacuations can be improved by 34.19%. This research provides valuable guidance for fire prevention, smoke exhaust, and emergency rescue operations in mines.