142 / 2023-06-29 18:44:34

A theoretical calculation method for critical air velocity to prevent methane draft pressure-caused airflow reversion based on vibration theory

coal mine,mine ventilation,methane draft pressure,airflow reversion,vibration theory

Methane draft pressure is a secondary disaster for mine ventilation following coal and gas outburst, which posed a long-term threat to coal mining and workers' safety. To study the law of methane draft pressure-caused airflow variation, vibration theory is introduced in this study. Vibration equation is used to deduct the basic equation of airflow oscillation in parallel upward ventilated airways, which regards the entire methane and air as one vibrating object in the loop of the parallel airways. The theoretical critical air velocity to prevent airflow reversion is calculated by the airflow oscillation equation using numerical methods. Furthermore, through dimensional analysis, a formula is given to calculate the critical velocity directly. The theoretical results were compared with experiments and good agreements was obtained, which verifies the rationality of the assumptions in the theoretical deduction process. The conclusion of this study indicates that, in a short time, vibration theory can be used to predict the critical air velocity to prevent airflow reversion, and be feasible in revealing the essence of methane draft pressure-caused airflow reversion.