Structure cellulaire de la détonation des mélanges H 2–NO 2/N 2O 4

Abstract

Calculations of the detonation reaction zone of gaseous reactive mixtures of NO 2/N 2O 4 as oxidizer and H 2, CH 4 or C 2H 6 as fuel, in the range of equivalence ratio Φ between 0.5 and 2, show that, for Φ⩾1, the chemical energy is released in two distinct and successive exothermic steps with different chemical induction times. The first exothermic stage is mainly due to the reaction NO 2+H→NO+OH, NO being the main oxidizer of the second one. The experimental study conducted on the same range of equivalence ratio (0.5⩽ Φ⩽2) shows that, for Φ⩾1, the detonation wave of these mixtures contains a double set of cellular structures. A similar result had already been obtained with the detonation of gaseous Nitromethane, the NO 2 group being here included in the molecule. Consequently, the oxidizer NO 2 being either initially separated from the fuel or included inside the molecule of a monopropellant (Nitromethane) is responsible, because of its specific chemical kinetics, of a chemical energy release in two main steps and of the existence of a double cellular structure in the detonation wave for the same range of equivalence ratio. These results reinforce the assumption that the cellular structure of the detonation finds its origin in the strong rates of chemical energy release inside the reaction zone. To cite this article: F. Joubert et al., C. R. Mecanique 331 (2003).