behzad Niknam - MSc mining engineering Amirkabir University

The mine face fire caused by methane combustion is an important incident that undermines the mine safety. Depending onits magnitude and intensity, fire may damage the mine's auxiliary ventilation system, thus exacerbating the consequences.With the help of computational fluid dynamics, this study investigates the effects of air curtain damage on the smokebehavior and temperature stratification in an active mine face. First, by modeling the Ingason–Hansen fire experiment, thenumerical model was validated, attaining excellent convergence between the numerical and experimental results. Next, a۲۵۰ kW fire was simulated in the mine face using square cells as large as ۵% of the characteristic fire diameter. Fivedifferent scenarios were considered to investigate the damage inflicted on the air curtain by the fire, including the referencescenario (S۰)—assuming no damage—and the first (S۱), second (S۲), third (S۳), and fourth (S۴) scenarios, in which ۱۷, ۵۰,۶۷, and ۸۳ % of the air curtain is damaged, respectively. Based on the simulation results, the required pressure difference isnot supplied between the cold air inside the curtain and the hot smoke outside when the air curtain length is reduced,undermining the chimney effect and allowing the smoke to fill up the model. In cases where more than ۵۰% of the aircurtain remains unaffected by fire, temperature strata can be separated into two distinct regions, namely the near-fire area—with stable stratification—and the areas further away—where hot and cold streams mix. However, a clear temperaturegradient is established along the vertical axis, resulting in a non-uniform temperature profile with a higher temperature nearthe ceiling and a lower temperature at the bottom. The same process holds until the boundary between clean air and smoke,and the smoke-free area. When the length of the air curtain is reduced fewer than ۵۰%, the chimney effect is canceledaltogether, but temperature strata remain unaffected near the fire. However, further away from the fire, the smoke coolsdown, the vertical temperature profile of the model levels out, the entire model fills up with smoke, and temperaturestratification is disrupted, leaving no chance for operators to escape from the mine face.

MINE FACE, CFD,FIRE, AIR CURTAIN, FIRE DAMAGE, TEMPERATURE, TEMPERATURE STRATIFICATION