The structure of the detonation front in gases

Abstract

We have carried out simultaneous visualizations of a chemical species (OH) and density gradients in the reaction zones of propagating detonations. We have directly imaged the characteristic shape of the chemical reaction zone and correlated this with the instability of the front. The observations have sufficient resolution to clearly see the variation in the reaction zone structure associated with leading shock velocity oscillations and complex flow behind the triple points associated with the intersection of transverse waves with the main front. Characteristic keystone-shaped regions of low reactivity are observed as predicted by previous analytical speculations. Observations on several types of mixtures are used to examine the issues of cellular regularity and the potential role of turbulence in the reaction process.

Numerical investigation on detonation cell evolution in a channel with area-changing cross section

“…The ZND model [1] was developed by modifying the C-J theory to introduce the induction and heat release zones to mimic the chemical reactions. Although the ZND detonation structure is different from the experimental observations, it initiated the new research by considering both thermodynamic parameters and hydrodynamic scales together, which shows the promising direction of the future experimental and numerical investigations on detonation dynamic scales, wave front structures and cellular detonation cells [2,3] . Further study showed that the detonation front is of the three-dimensional structure that consists of incident shocks, Mach stems, transverse waves, reaction zones and shear layers.…”