Numerical Simulation On Ventilation Leakage And Gas Distribution Under Plugging Pipes In Upper Corner Of Gob

Researching on ventilation leakage and gas distribution of gob under plugging pipein upper corner has greatly important theoretical and practical significance forincreasing the gas drainage efficiency, controlling gas beyond in upper corner,preventing the spontaneous combustion in gob and gas explosion.According to the basic theory of computational fluid dynamics, through the Fluentsoftware the thesis researches on the influence of mesh generation on the results of flowsolving in working face and gob. The results show that: there are obvious eddy zones inthe upper corner and bottom corner by using boundary layer mesh, when the girdspacings of working face are0.4m and0.2m, the gird spacings of gob are1m and0.5m,the result of the numerical simulation have significant difference, when the girdspacings of working face are0.2m and0.1m, the gird spacings of gob are0.5m and0.25m, the differences of the result of the numerical simulation are small.The3D model of working face and gob under U type ventilation is establshed.Through the Fluent software, the paper researches on ventilation leakage and gasdistribution in working face and gob. Quantitative analysis of the results show that thegas concentration of gob increases with the distance along deep in gob. After a certaindistance deep in gob, the gas concentration can reach100%. The gas concentration isgradually bigger from the bottom to the top of gob, which can reach70%above15m tothe bottom. The local high-concentration gas present to the upper corner where is at thereturn air side and the closer to the working face, the higher gas concentration of thelocal high-concentration gas is.Researching on numerical simulation of the gas concentration rules in gob underplugging pipes in upper corner, the gas concentration of gob are lower than that of notusing gas drainage.The gas is pouring into the gas drainage pipe that result in the gasconcentration surrounding the gas drainage pipe reduces significantly.By the numerical simulation and comparision extracting result under differentnegative pressure, when the negative pressure of suction rises gradually, the mixed flowin gas drainage pipe increases gradually, the gas drainage concentration steady decreaseand the amplitude reduction of gas drainage concentration increases gradually, the gas drainage volume increases gradually and the increase amplitude steady decrease.Whenthe negative pressure is2000Pa, the gas drainage volume is basically stable.The gasconcentration in upper corner reduces significantly and increases as negative pressure ofsuction rising.The air leakage quantity increases gradually when the negative pressure of suctionrises gradually. By contrastive the vector graphic, the influence scope of ventilationleakage along deep in gob becomes larger and expands constantly as negative pressureof suction rising. By contrastive and analysis velocity distribution in deep in gobdirection of a monitoring line on the interface between the working face and gob, wefound that the scope of air leakage from working face to gob becomes larger andexpands constantly as negative pressure of suction rising. When the negative pressure ofsuction rises at a certain extent, there is an abnormal phenomenon that air leakage fromworking face to gob near the return airway.