Numerical Determination of Gas Velocity and Concentration Fields in Goaf Space of an Underground Hard Coal Mine
DOI:
https://doi.org/10.29227/IM-2026-01-01-008Keywords:
velocity field, gas mixture, numerical model, goaf spaceAbstract
The study develops a numerical model of gas flow and composition in a goaf formed after longwall coal extraction. The goaf is treated as a horizontal rectangular porous slab with thickness equal to 3.5 times the mined seam thickness. Air from the mine ventilation system flows into this porous region through adjacent headings, while methane is released from the methane-bearing strata and carbon oxidation occurs within the rubble. The model also includes local nitrogen injection with a specified volumetric flow via a pipeline along the long edge of the goaf. Using the Control Volume Method, the authors compute two dimensional discrete fields in the goaf: overpressure, apparent velocity of the gas mixture, and molar concentrations of nitrogen, methane and oxygen. The resulting computer programs determine these fields for two ventilation layouts, corresponding to typical systems used in longwall mining, each with distinct boundary conditions. This approach enables quantitative assessment of gas migration and distribution patterns in the caving zone, supporting ventilation design and evaluation of methane and oxygen hazards.
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