Scott Davis

Complex explosion development in mines: Case study—2010 upper big branch mine explosion

On April 5th, 2010, a methane explosion occurred within the Upper Big Branch mine south of Charleston, WV. Twenty‐nine men lost their lives as a result of a flammable concentration of methane that built up in the enclosed space and ignited, resulting in a methane explosion that transitioned into a coal dust explosion. This study used the FLACS computational fluid dynamics solver to conduct a detailed explosion analysis to evaluate the complex overpressure development throughout the mine as a result of the flammable cloud ignition. As a result of the accident investigation, unique explosion patterns were found in the mine where certain “blast indicators” within the mine shafts were deformed in such a manner that was inconsistent with the likely flow of the expanding blast wave. The FLACS analysis will analyze the explosion dynamics and shed light on the damage observations made after the blast.

Do not believe the hype: Using case studies and experimental evidence to show why the HSE is wrong about excluding deflagration‐to‐detonation transitions

A recent report by the UKs Health and Safety Executive postulated that severe explosions can propagate at subsonic speeds but generate overpressures of several bar in open areas and this “new” type of explosion is episodic in nature. The UK Health and Safety Executive (HSE) paper based their findings on a specific interpretation of historical data and “empirical evidence” from previous incidents and selected experimental data. They indicate that their results should guide plant design and risk assessment. The report fails to take account of key evidence from recent large‐scale experimental studies and incident investigations in proposing a hypothetical explosion mechanism over those that are known to occur and are well understood. This has the potential to misdirect efforts to manage such events.

Investigation findings and lessons learned in the west fertilizer explosion

On 17 April 2013, an explosion occurred at the West Fertilizer Company storage and distribution facility in West, Texas. The explosion at West Fertilizer resulted from an intense fire in the seed and storage area of the facility that led to the detonation of approximately 30 tons of ammonium nitrate stored inside a wooden receiving bin. The explosion occurred while emergency services personnel were responding to a fire at the facility. Fifteen people were killed, more than 250 were injured, and numerous buildings were damaged or destroyed. This article presents the results of our investigation into the cause and origin of the explosion event, which included (1) early video footage which showed the room where the initial fire originates and (2) applying advanced blast techniques to determine the quantity of ammonium nitrate that likely detonated during the blast. These techniques included near-field blast effects (e.g. the resulting crater left by the blast) as well as the far-field blast damage resulting in the neighboring community.

Can gases behave like explosives: Large-scale deflagration to detonation testing:

A large vapor cloud explosion followed by a fire is one of the most dangerous and high consequence events that can occur at petrochemical facilities. However, one of the most devastating explosions is when a deflagration transitions to a detonation, which can travel at speeds greater than 1800 m/s and pressures greater than 18 barg. This phenomenon is called a deflagration-to-detonation transition, whereby the deflagration (flame front) continues to accelerate due to confinement or flow-induced turbulence (e.g. obstacles) and ultimately transitions at flame speeds greater than the speed of sound to a detonation. Unlike a deflagration that requires the presence of confinement or obstacles to generate high flame speeds and associated elevated overpressures, a detonation is a self-sustaining phenomenon having the shock front coupled to the combustion. Once established, the resulting detonation will continue to propagate through the vapor cloud at speeds (1800 m/s) that are of similar order as high explosives (7000–8000 m/s). While there are differences between high explosives and vapor cloud explosions (e.g. high explosives can have pressures well in excess of 100 bar), vapor cloud explosions that transition to detonations can cause significant damage due to the extremely high pressures not typically associated with gas phase explosions (>18 barg), high energy release rate per unit mass, and higher impulses due to large cloud sizes. While the likelihood of deflagration-to-detonation transitions is lower than deflagrations, they have been identified in some of the most recent large-scale explosion incidents. The consequences of deflagration-to-detonation transitions can be orders of magnitude larger than deflagrations. This article will present the results of large-scale testing conducted in a newly developed test rig of 1500 m3 gross volume involving stoichiometric, lean, and rich mixtures of propane and methane.