Simulation Study On The Migration Rules Of Gas In Upper Corner And Goaf Area In Coal Mine

Along with the continuous mining of coal mine,there is continuous gas disaster.In order to effectively prevent the gas accumulation in upper corner and gas concentration overrun in gob,based on the basic theory of computational fluid dynamics and porous media,FLUENT software was used to establish the three-dimensional model of working face and gob with different coal seam inclinations and different ventilation modes,the control equation of gob air and gas was determined,and the flow field in gob and gas migration law was studied by numerical simulation calculation.The results show that different ventilation modes and the angles of coal seam has a great influence on the air flow distribution and gas migration in the gob.The air leakage of working face with different ventilation modes can flow into the gob area from the next corner and lower face,and the internal gas will flow into the working face by the air leakage through the upper corner and upper face.The air leakage will increase with the increase of the dip angle of coal seam,but the total gas quality will decrease with the increase of lt.For Y type and J type ventilation,when the airflow from intake airflow roadway flew to turning point of the working face,the velocity of airflow in vertical direction would sharply decrease under the function of centrifugation,the dynamic pressure turned into static pressure and the eddy was formed in the bottom corner.The fluid with larger speed and smaller radius of curvature would form eddy area at the inner side of working face after it flew the turning point,and the eddy area in the next corner would decrease with the increase of the dip angle of coal seam.When the airflow from intake airflow roadway flew to turning point of the upper corner,the eddy area would be formed at the inner side of upper corner,and the large eddy current was formed under the function of resistance after it entering the lane along the empty lane.The air leakage would increase with the increase of the dip angle of coal seam,and the eddy area would decrease with the increase of the air leakage.Comparing with U type ventilation,Y type and J type ventilation can be a great solution to the upper corner gas accumulation problem,which also plays an important role in the safety production of working face.