Experimental Investigation and Modeling of the Formation of Explosive Concentrations

Excess pressure is the main indicator characterizing the magnitude of explosive loads during emergency gas explosions. The value of this parameter and the entire accident scenario as a whole directly depend on the concentration of gas entering the room. Any typical room is characterized by the presence of two processes: laminar and turbulent diffusion. The laminar diffusion coefficient depends on the main characteristics of the gas (pressure, temperature). The laminar diffusion coefficient depends on the main characteristics of the gas (pressure, temperature). The coefficient of turbulent diffusion is determined only by the turbulent structure of the considered medium. It is established that the incomplete vortex mixing of gas with air is sufficient for flame propagation. This indicates the importance of studying the process of turbulent diffusion from the point of view of the formation of explosive gas-air mixtures. The purpose of the study is the experimental and computational determination of the coefficient of methane turbulent diffusion. This characteristic is required to assess the state of the gas-air environment in the room. It can be used in the development of explosion prevention measures, for example, in the design of a ventilation system. The study of the process of formation of explosive concentrations was carried out on the basis of an experiment and subsequent comparison of its results with a calculation model. In the course of the studies, it was established that the coefficient of turbulent diffusion, due to which explosive mixtures are formed, exceeds the coefficient of molecular diffusion by two orders of magnitude or more and is at least 4∙10–3 m2/s. The applied mathematical model and calculation scheme adequately describe the course of the experiments. Determination of the turbulent diffusion coefficient will allow assessing the state of the gas-air environment in the room and determining the required measures to prevent a possible emergency explosion.