Mechanical characteristics of partially premixed methane/air explosion in a small closed tube based on simulation technology

Abstract

ABSTRACTTo 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.