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

Abstract

Methane draft pressure is a secondary disaster for mine ventilation following coal and gas outbursts, which poses a long-term threat to coal mining and workers’ safety. To study the law of methane draft pressure-caused airflow variation, oscillation theory is introduced in this study. The 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 were obtained, which verifies the rationality of the assumptions in the theoretical deduction process. The conclusion of this study indicates that, in a short time, oscillation 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.

HIGHLIGHTS

• An airflow oscillation model is built to analyze and predict methane draft pressure-caused airflow reversion based on oscillation theory.

• A method is carried out to calculate the critical velocity that prevents airflow reversion based on the airflow oscillation model.

• The conclusions of this paper provide a theoretical basis for further understanding the essence of the airflow reversion caused by methane draft pressure.

Keywords:

• Coal mine
• mine ventilation
• methane draft pressure
• airflow reversion
• oscillation theory

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This paper is supported by the National Natural Science Foundation of China (No. 52004255) and Henan Science and Technology Research Project (Nos. 232102320235 and 232102320046).

Notes on contributors

Zeqi Wu

Zeqi Wu received his Ph.D. degree of safety science and engineering from China University of Mining and Technology, Beijing. He is a lecturer who is currently working at school of Building Environment Engineering, Zhengzhou University of Light Industry. His area of research include mine ventilation, mine gas prevention and control, and fire smoke control.

Kai Wang

Kai Wang is a professor who is currently working at College of Emergency Management & Safety Engineering, China University of Mining and Technology, Beijing. He majors in mine ventilation and safety, gas outburst and coal mine safety.

Huaitao Song

Huaitao Song is a lecturer who is currently working at school of Building Environment Engineering, Zhengzhou University of Light Industry. He majors in mine ventilation and thermal hazards in mines.

Kun Wang

Kun Wang is currently working toward the M.S. degree in electrical engineering with the school of Building Environment Engineering, Zhengzhou University of Light Industry. His research interests include coal mine safety and fire smoke control.

Lin Shao

Lin Shao is an experimentalist who is currently working at school of Building Environment Engineering, Zhengzhou University of Light Industry. Her majors in coal mine safety.