ABSTRACT
To effectively deal with the methane/air explosion from the leakage in natural gas industry or the gas accumulation in coal mine, this paper studied the mechanical characteristics of partially premixed methane/air explosion in a small closed tube based on simulation technology. Ansys Gambit was used to establish the tube model with a diameter of 0.1 m and a length of 1 m. The length of the premixed zone was set as 0.2 and 0.3 m, respectively. The partially premixed methane/air explosion was numerically simulated by Ansys Fluent at the concentrations of 6%, 8%, 9.5%, 11%, and 14%. It focused on the mechanical characteristics of methane/air explosion under different concentrations and different premixed zones. The results show that the maximum overpressure (0.229 MPa) of methane/air explosion with the premixed length of 0.3 m and at the concentration of 14% is the largest of all. In the first 50 ms, the rate of pressure rise reaches a peak, and then continues to maintain a lower value. However, the rate of pressure rise shows a certain fluctuations after 50 ms at the concentrations of 11% and 14%, which is related with the propagation of the premixed gas to the non-methane-occupied zones. This maintained the explosion intensity, increasing the explosion overpressure and even leading to the largest explosion overpressure in the study.
Acknowledgments
The authors specially thank Professor Qi Zhang from Beijing Institute of Technology for his help with numerical simulation.