Analysis of planar detonations in the presence of non-thermal termolecular reactions

Hydrogen-based detonations constitute a promising sustainable propulsion system for high-speed vehicles. For conditions associated with a detonation, the reacting mixture may undergo non-thermal reactions prior to reaching a thermal equilibrium state. Highly energetic ephemeral radicals undergo reactive collisions with radicals during thermalization and can be represented with chemically termolecular reactions, which have been previously shown to affect important characteristics in reacting systems such as deflagration-to-detonation transition. In this work, we investigate the effects of non-thermal termolecular reactivity on characteristics of planar detonation waves. We conduct high-fidelity numerical simulations of cellular detonation involving hydrogen combustion in a two-dimensional channel on an adaptively refined grid. Our thermodynamic parameters span different regimes identified through Zel’dovich-von Neumann-Döring (ZND) solutions, in which termolecular reactions were found to have opposing effects on detonation characteristics such as induction zone length. We study the effects of non-thermal reactivity on the kinematics and dynamics of the planar detonating system in these different regimes with a particular focus on cellular structure.