Effect of Containment on Transition from Deflagration to Detonation

Abstract

In general, the transition from deflagration to detonation consists of two separate sequential events: 1) flame acceleration, which generates turbulence and shock waves ahead of the reaction zone, and 2) a local explosion, which is the initial step for the onset of detonation. Flame acceleration creates the necessary conditions for the onset of detonation, and the local explosion is the process that creates the detonation wave. Confinement of the combustible mixture by surrounding walls plays an important role in the transition process by controlling the rate of flame acceleration. If venting of the burnt gas through a side wall is possible, the coupling between the unburnt gas flow and the combustion process is weakened, thus reducing the potential for flame acceleration. Under such conditions, the critical shock strength or the critical turbulent intensity required for onset of detonation may never be reached, and the likelihood of a transition to detonation is greatly reduced .