Ignition and detonation in N2O-CO-H2-He mixtures

Abstract

Ignition and deflagration-to-detonation transition in the N 2 O-CO-H 2 system behind the reflected shock wave in initial temperatures ranging between 1200 and 1800 K and pressures of 3–9 atm are studied. It is established that the chemical reactions are described adequately by the assumption of equilibrium between the translation-rotational and internal degrees of freedom of the molecules for shock-heated gas conditions. It is found that both the total heat release Q by the chemical reactions and the ratio of the induction period τ ind of the mixture to the characteristic energy release time θ are the parameters governing the flow pattern. Two different modes of interaction between the exothermic reaction and the gas flow are distinguished. The single-front mode, with a single discontinuity, arises when τ ind ≤θ, and two-front mode, in which a strong discontinuity formed behind the reflected shock front caused by interaction between the gasdynamic and chemical processes, arises when τ ind ≫θ.