New Technology for Preventing and Controlling Air Leakage in Goaf Based on the Theory of Wind Flow Boundary Layer

Abstract

Air leakage in the goaf is a fundamental reason for the high-temperature heat damage of the coal mining face and the gas concentration in the upper corner exceeding the limit. Combined with the boundary layer theory, this study analyzes the airflow state of the coal mining face. We propose installing a new air curtain system to prevent air leakage in the goaf. The length of the intake air curtain is determined by solving the theoretical equation. Numerical simulation is used to study different layout schemes of air curtains, and the spatial distribution law of different air volumes inside the working face is analyzed. The simulation results are compared with the field-measured data. The results show that when the length of the air curtain on the air inlet side is 20 m, the wind flow on the working face can be approximated as a state of attached jet, and a diffuse turbulent flow area will be formed outside the air curtain. Gas concentration will increase in this area. The air leakage prevention effect is best when the air curtains with a length of 20 m for the inlet air and 10 m for the return air are arranged at both ends of the working face. This air curtain system can reduce the temperature of the working face and the gas concentration in the upper corner and has certain guiding significance for the air leakage prevention work in the goaf.