Research On Air Leakage Flow Field And Gas Distribution In Gob

Ventilation mode used in face has grate effect on gob flow and gas migration. Numerical simulation has informed on airflow field and gas distribution in gob. The results showed that there is a dominant difference in air leakage, airflow flow and migration when seam obliquity and ventilation mode of face are different. When the ascensional ventilation, Air linkage went into the gob from the lower corner of face and lower face, while Air Leakage of gas carried went into the face from upper corner upper face. When pressure ventilation of face descentional ventilation was weaker than the natural pressure in the gob, the phenomenon of gas reflux would be occurred. Air leakage was flowed into the gob from corner and lower department of face, gas carried flowed into face from upper corner and upper department. Air leakage rate of gob ascensional ventilation was grater than of descentional ventilation, and air leakage rate of ascensional ventilation would be increased as coal seam angle increased. When the pressure of descentional ventilation was smaller than natural pressure, air leakage rate also would be increased with coal seam angle increased. Gas volume of gob which descentional ventilation was greater than the ascensional ventilation; with coal seam angle increased, Gas volume would reduced whether in ascensional ventilation or in the descentional ventilation.When the pressure of descentional ventilation was greater than natural pressure, in the shallow gob, working for air leakage from mining into the upper corner and the upper part of gob, from the mining face and the next corner into the lower part of the face; in the deep gob, caused by the concentration difference of gas diffusion dominant gob gas to shallow diffusion, and then with the leakage of airflow from the face and the next corner into the lower face. When the coal seam angle exceed a certain angle, gas reflux inside the gob did not occur, the greater the coal seam angle, flow velocity decreased, total amount of gas in the amount of air leakage reduction with increased.