Simulation Study On Stope Gas Migration Laws Of "U+L" Ventilation System Of Two Intakes And One Return In Comprehensive Mechanized Coal Mining Working Face

Goaf methane is one of the important emission source of coal mining working face, further study and treatment on goaf methane is necessary for coal industry. Based on 14205 working face of Shaqu Coal Mine, this thesis analyses goaf methane emission source, factors and flowing characteristics in comprehensive mechanized coal mining working face. Combining mathematical model of gas flow and similarity theory, numerical simulation and similar material experiment was finished; this thesis summarizes goaf methane migration laws of"U+L"ventilation system of two intakes and one return in comprehensive mechanized coal mining working face.Based on the theory of gas percolation, law of mass conservation and hydrodynamics, basic mathematical equation of gas flow model was established. According to 14205 working face of Shaqu Coal Mine, the numerical simulation of goaf methane migration was carried out by FLUENT, which calculated the three-dimensional distribution laws of methane concentration, that is, mining direction, vertical and width direction.The effect of different ventilation system and inlet wind speed on goaf methane concentration distribution was studied, which indicated that"U+L"-shaped ventilation system of two intakes and one return can reduce the goaf methane concentration as well as that of working face and top corner. By enhancing the wind speed, the higher concentration methane can move to deeper goaf, which can reduce the methane concentration in working face and top corner.According to similarity theory and similar material experiment, the thesis studies qualitatively flowing patterns and distribution laws of methane concentration, which verifies the results of numerical simulation to goaf methane migration laws. It is indicated from the results of experiment that flowing patterns and distribution laws of methane concentration are coincident with numerical simulations, and the methane concentration from working face and top corner can be reduced by using"U+L"-shaped ventilation system of two intakes and one return.It is fixed of high concentrations gas area in goaf by similar simulation of goaf methane migration laws, that is, 40-250m (mining direction), 30-40m (vertical direction) and 40m (width direction) .This area which is dynamic forward with the face is the best and reasonablest place of gas drainaging in working face. The research supports preventing gas accumulation and selecting a reasonable area and patten of gas extraction.It concludes high coincidence by comparing the similar simulation results with three-dimensional distribution of methane concentration (mining direction, vertical and width direction ). from 14205 working face of Shaqu Coal Mine. That is to say it is possible of using similar simulation to gas prevention research.