| Oil gas association mining area is more likely to occuring large fluctuation range of gas emission in surrounding rock, which is particularly serious emission from the bottom. The phenomenon has the characteristics of sudden, concealment and emission too much etc, becoming the new disaster causing factors affected to the mine safety and high efficiency mining. Preliminary studies suggest that abnormal emission, different from gas and coal seam gas, genetic types of oil type gas. In the light of the oil gas association mine, heading face gas emission for numerical simulation been choosed. Comparison and analysis of main components of the diffusion rule of CH4 tunneling working surface air flow field and oil type gas to provide the basis for the oil and gas symbiotic mine oil type gas treatment.According to the actual conditions of laneway airflow and flowfield distribution, physical and mathematical models of airflow field in forced ventilation were established on the basis of jet theories, aerodynamics, fluid mechanics and computational fluid dynamics by software fluent, boundary conditions were also confirmed. Laneway airflow was described by Realizable k- e model and wall functions, so flowfield distribution and jet velocity variation were obtained through numerical simulation on the process of laneway forced ventilation. On the basis of credible numerical simulation, flowfield variation and distribution of CH4 concentration were studied through different variable of emission location, flux, cylinder position. The effects of these influencing factors on CH4 diffusion were obtained.The numerical simulation results show that: the emission point is divided into four areas according to character of CH4 in diffusion concentration in tunnel. CH4 concentration arrangement conducive to the discharge of oil type gas in the top of the more. Emission point for the cracks perpendicular or parallel to the driving direction is not conducive to been expelled. Increasing the amount of oil type gas gush, gush is stable after CH4 concentration of each position of the tunnel will be a corresponding increased, and the increase degree obey the strict proportion. In a certain range of air supply is effective to increase the discharge of oil type gas, especially the emission point in the third section, but this approach has limitations, the amount of exhaust gas will no longer increase beyond a certain value. Flow field has an essential influence on oil type gas diffusion, the greater the wind speed, the smaller CH4 concentration in the top of tunnel. |
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