The study of spontaneous combustion region partition and nitrogen injection effect forecast based on CFD method

In order to understand the contribution of spontaneous combustion dangerous region under U type ventilation in gob area, mathematical model describing air flow and temperature heating was established according to mass, momentum and energy conservation equations and solved by FLUENT software. The calculation results show that oxygen mainly concentrates in front of gob near face and decays along depth. Since oxygen consumes along the track, oxygen concentration in intake way is much higher than that in return way, and the air leakage speed near work face is much higher than depth of gob. Thus, dangerous region is divided by oxygen and air leakage criterion. Besides, the area near work face has lower temperature than oxidation region by the effect of heat dissipation while temperature in depth gob decreases gradually due to the low oxygen concentration. Heating process can be seen as an accelerating process. Nitrogen injection can decrease the oxidation scope effectively. Nitrogen injection position in dissipation area is better than in oxidation area. Calculation results reflect the real situation objectively and can be referenced by real engineering practices.