More on Mechanisms of DDT in Reactive Gases

摘要

This paper is a brief review of several mechanisms of deflagration-to-detonation transition (DDT) in energetic reactive gases, with a view towards comparing and integrating the underlying concepts. The standard mechanism we have studied extensively in the past is detonation ignition in a gradient of reactivity. Another method of creating a detonation is direct ignition, which involves depositing large amounts of energy in a portion of the gas. This seems to bypass the need for a previously existing turbulent flame and goes directly to the formation of strong shocks. Now we discuss several variations and elaborations of these involving shock focusing in unreacted gas, spontaneous ignition in turbulent media when there are no walls or obstacles, and shock-amplification by flames. All of these processes may occur in the presence of a turbulent flame, which sets up the conditions that amplify shocks and can create hot spots in which reactivity gradients may arise.