Deflagrations, Detonations, and the Deflagration-to-Detonation Transition in Methane-Air Mixtures

TLDR: In this article, large-scale numerical simulations, in conjunction with experimental work conducted at the National Institute for Occupational Safety and Health?s Gas Explosion Test Facility, were performed to address four specific problems: flame acceleration and deflagration-to-detonation transition (DDT) in obstructed channels containing a stoichiometric methane-air mixture.

Abstract: : Explosions in mixtures of natural gas (NG) and air have been of intense practical concern for coal mines for many years. Potentially explosive mixtures of NG and air can accumulate in the active ventilated areas or in unventilated sealed areas of these mines. If an ignition source, such as a simple spark, ignites the NG-air mixture and creates a flame, the initially slow-moving flame can become turbulent, accelerate rapidly, develop extremely intense pressure waves, and potentially generate enormous stress on coal mine seals. In this work, we attempt to answer the question: Given a large enough volume of flammable mixture of NG and air, can a weak spark ignition develop into a detonation? Large-scale numerical simulations, in conjunction with experimental work conducted at the National Institute for Occupational Safety and Health?s Gas Explosion Test Facility, were performed to address four specific problems: flame acceleration and deflagration-to-detonation transition (DDT) in obstructed channels containing a stoichiometric methane-air mixture, flame acceleration and DDT in fuel-lean and fuel-rich mixtures, effects of spatially varying fuel concentrations on detonations, and stochastic effects on flame acceleration and DDT.