Numerical simulation of an emergency explosions of the mining atmosphere

Abstract

Purpose. Development of an effective scheme for numerical calculation of the joint solution of the problem of gas dynamics and chemical kinetics of combustion of a gas-air medium on the basis of the large-particle method. Methods. Mathematical modeling, numerical experiment, analysis and generalization and results. Findings. For joint solution of problems of gas dynamics and chemical kinetics of combustion gas environments proposed in the numerical scheme of the method of large particles concentration function, which allows to take into account the multicomponent composition of the gas medium. This function is determined at the stage of formation of the calculation area and in each cell of the calculation scheme it determines the mole fraction of each substance. The function is involved in the calculation of mass flows across the boundaries of the calculated cells, determining the mass of the overflow for each substance. The concentration function makes it possible to introduce into the numerical scheme the equations of chemical kinetics in the form of the Arrhenius equation and to distinguish the chemical reaction components and combustion products. In the problem of calculating detonation explosions, strong pressure gradients arise which, when the front of the shock wave reaches the free exit boundary, nonphysical fluctuations of the parameter are generated. To exclude their influence on the process under consideration, various types of approximation of parameters in the fictitious layer of the design scheme are analyzed. From the analysis of physical processes an effective Физико-технические проблемы горного производства 2020, вып. 22 86 form of the boundary conditions is found for a free yield for the problem of propagation of a shock wave in a channel. Originality. Modification of the numerical method of large particles due to the introduction of a concentration function allows the joint solution of the problem of gas dynamics and chemical kinetics of explosive combustion of a gas-air medium. For correct operation of the boundary conditions, a free exit into the conditions of discontinuous flows is developed for the scheme of approximation of the parameter in a fictitious layer on the basis of the shock adiabat of a particular gas. Practical implications. The modification of the large-particle method makes it possible to conduct a numerical experiment on the calculation of safe distances in emergency gas explosions in coal mine conditions, and also on the basis of calculating the propagation of a shock air wave through a channel to determine the dynamic loads on explosion-proof structures.