Study On The Tridimensional "W" Air Dynamic System Of Productive Coalface With High Gas Emission

Based on analyzing the characteristics of ventilation system patterns and measuring the parameters of gas at coalfaces,the structure of three-dimensional "W" aerodynamic system is designed based on the theory of aerodynamics,which consists of 'U' ventilation system,bundle drills and pumping roadways.The structure parameters of tridimensional "W" aerodynamic system are studied by simulating the situation of air flow field in gob area,gas field,displacement of overlying strata and the effect of gas drainage using soft of CFD and FLAC.Logical distance and the incline range of bundle drills are obtained.The result shows that the degree of damage is less when the bundle drills are arranged in the range of 50m under the returning ventilation roadway and the dip is -60°.The effect is better when the amount of drill bores is between 7 and 10.The law that the effect of gas control in working face becomes better when the distance between drills and bundles becomes shorter is obtained;the further of the distance between working face and bundle drills,the worse of the effect of gas controlling.Results of simulation and industrial experiment show that bundle drills in three-dimensional "W" aerodynamic system increased the amount of sinks in gob area effectively;it closed the channel through which gas can flow to working face just like a fence,and makes the gas flow to the pumping roadway in high position through bundle drills.Finally pumping rate is promoted in working faces of high gas and high production and gas concentration is decreased in extracting area.In order to meet the demand of simulation,porosity and resistance of air leakage in different positions of gob area are studied according to the data of equivalent material simulation test.According to the relationship of actual velocity and seepage velocity of air flow in gob area,mass transfer unified equation of air flow in extracting areas is deduced and established;characteristics and influencing factors of gas emission in working face of high gas and high production are studied using the method of combination of both field measurement and theoretical research.Conclusion is that coal production and gas content in coal seams are main influencing factors of the gas emission amount in high gas and high production working faces.A new method—analogy is proposed,which can be used for forecasting the gas emission amount between adjacent sections of same coal seam.