Numerical Analysis of the Influence of Ventilation at Working Face on Air Leakage in Gob

Abstract

Air leakage is a key factor that leads to spontaneous combustion of residual coal in gob, and the ventilation at the working face is the direct reason for air leakage from the working face to the gob. A model of the resistance coefficient of air leakage was established based on "O"-type caving and compaction and nonlinear seepage theories to study the influence of ventilation at working face on air leakage from the working face to the gob. Computational fluid dynamics (CFD) software, Fluent, was used to simulate the flow field of the air leakage at the experimental working face with a high drainage roadway. The air volumes obtained by simulation were consistent with the field-measured data at the experimental working face. On the basis of the simulation, the influences of wind resistance and air volume at the working face on air leakage were studied. Results show that reducing the wind resistance at the working face plays a positive role in controlling the air leakage volume from the working face to the gob. When the wind resistance at the working face reduces by 50%, the air leakage volume reduces by 28%. Meanwhile, the effects of air volumes at the working face on air leakage volume are different. A critical value of air volume at the working face is determined (24.27m³/s). Only when the air volume at the working face is more than the critical value can the air leakage volume from the working face to the gob be effectively decreased by reducing the air volume at the working face. This study provides guidance for the prevention and control of air leakage in gob.