Modeling the stability of air flows in inclined workings in case of fire

Purpose. Development of a mathematical model and study of the processes occurring during conveyor belt fires in inclined mines to determine the mechanism of air flow distribution under appropriate conditions. Methods. Practical measurements of the distribution of air flows in an inclined conveyor operated at the mining and processing plant of PJSC ArcelorMittal Kryvyi Rih were carried out. Based on the obtained data, a mathematical model was crea-ted, which was then used to perform Computational Fluid Dynamics (CFD) modeling of gas flows in the mine under normal conditions and in the event of a fire with a thermal capacity of 9 MW. Findings. The study reveals the peculiarities of gas flows during the combustion of a conveyor belt in inclined workings, as well as the influence of turbulence on the flow, changes in the density of gases during heating, and the impact of gravity on the distribution of gases in the cross-section and along the length of the workings. A fire centre with a heat output of 9 MW has a significant impact on the distribution of air flows. The phenomenon of thermal expansion results in a 59.2% increase in the volume of gases behind the fire. The thermal expansion of gases and their low density have a significant impact on the formation of gas flows in inclined workings. As the jet moves away from the centre of the fire, the velocity of the jet gradually increases, reaching a value of 12.4 m/s. This results in a notable alteration in the distribution of total pressure across adjacent workings, accompanied by an increase in flow turbulence. Consequently, the mass of air exiting the right branch is observed to have a five-fold increase in comparison to the pre-fire state. The overturning of the jet from the left branch of the workings gives rise to the exclusive distribution of combustion products along the right branch. Originality. The study helps to understand the mechanism of jet overturning and the peculiarities of the distribution of combustion products in case of fire in inclined conveyor workings. Practical implications. The results of the research allow us to predict the probability of fire, identify the most dangerous areas for fire, and plan the most rational actions for firefighting in specific unique conditions.