Numerical investigations of airflow patterns on a longwall face
To thoroughly understand the ventilation flow characteristics on a longwall face, six computational fluid dynamics (CFD) models representing six consecutive longwall operating scenarios were developed. Key features of the longwall equipment and an immediate goaf were embedded into the models to obtain a realistic ventilation flow field. The occurrence of flow separation at both intersections of maingate/tailgate and face were revealed by the model results. Control measures are therefore suggested to minimise the potential accumulation of hazardous gas and dust within the flow separation zones. Significant air leakage to the goaf would occur if maingate curtain were not used. The impact of shearer position and its cutting direction on face ventilation was regional, indicating the stability of face ventilation system. These new insights into the complex longwall ventilation flow patterns will eventually be beneficial to the hazardous gas and dust management at longwall faces of underground coal mines.