Numerical Simulation of Drainage Quantity in Advanced Diversion Hole in Close Coal Seam Composite Gob Area

In order to explore the impact of drainage quantity of advanced diversion hole on distribution of oxygen and methane in gob,using ANSYS numerical simulation software,the establishment of complex goaf three-dimensional mathematical model is established and the numerical simulation is carried out. Results demonstrates that the reasonable range of the quantity of drainage in advanced diversion hole is from 57 m³/min to 68 m³/min, and CO concentration at upper corner is less than 12×10^-6;the maximum gas concentration at 81004 working face,upper corner,and return air lane is controlled within 0.8%,which can ensure the safety of working face.