Unconfined deflagrative explosion without turbulence: Experiment and model

Literature Survey of Crude Oil Properties Relevant to Handling and Fire Safety in Transport

“…Deflagrations can produce overpressures of up to around 0.8 MPa (115 psi) with obstacles and under 10 kPa (1.5 psi) without obstacles, while detonations produce overpressures up to around 2.0 MPa (300 psi). Open air vapor cloud explosions using low energy ignition sources will result in a deflagration without damaging overpressures (Leyer, et al, 1993). Additional hazards from explosions are fragments resulting from damaged structures.…”

“…The type of explosion that occurs depends on the strength and geometry of the ignition source, fuel, degree of confinement, and obstacle density. A deflagration may transition to a detonation when there is a high degree of confinement or blockage such as with closely spaced obstacles (Leyer, et al, 1993). The obstacles will create turbulence, which enhances the burning surface area and increases the local burning velocity.…”

The quantitative assessment of domino effects caused by overpressure

“…Thus, a different approach for the estimation of "far-field" threshold distance is needed. In view of the very large ignition energy required to initiate directly the detonation of a fuel-air mixture, detonation regime can be ruled out in practical conditions, whereas deflagration regime is more likely and sufficient to explain "experimental" observation of damage in vapour cloud explosion [18]. Hence, only deflagration will be considered in the following.…”

Influence of built-in obstacles on unconfined vapor cloud explosion

“…Van den Berg et al (1993) demonstrated that fundamental and practical objections were met if the TNT-equivalency concept is used for vapor cloud explosion hazard assessment, while the Multi-energy concept was shown to be a flexible concept which made it possible to incorporate current experimental data and advanced computational methods into the procedure of vapor cloud explosion hazard analysis. Leyer et al (1993) proposed that the flame would accelerate when meeting the concentration gradient or turbulence and vortex caused by obstacles. Chen et al (2009) studied the influence of obstacles on confined vapor cloud explosion by use of numerical simulation.…”