Numerical investigations of ventilation and methane flow behaviour around the longwall shearer
Gas management in underground coal mines remains a challenging issue for mine operators. Computational Fluid Dynamics (CFD) models of typical longwall faces have been developed and validated using field ventilation survey data. The models were then used to study both airflow and methane dispersion patterns as a result of different shearer cutting sequence. Modelling results show that shearer cutting sequence has a significant influence on the face ventilation airflow and hence gas accumulation around the shearer. When the shearer is cutting from MG towards TG, the maximum gas concentration close to the coal face can reach as high as 2.00%, a situation which may not be detected timely by gas sensors currently mounted on the shearer. The accumulation of methane is more significant in the MG-TG pass, where the methane-air mixture may fall in the explosive range around cutting drum.