Vibrational nonequilibrium and reaction heat effect in diluted hydrogen-oxygen mixtures behind reflected shock waves at 1000

Abstract

Vibrationally nonequilibrium model of kinetics in the reacting mixture H2 + O2 + Ar behind the reflected shock wave is formulated as a non-isothermal process occurring adiabatically at a constant volume. The model takes into account the vibrational nonequilibrium for the starting (primary) H2 and O2 molecules, as well as the molecular intermediates HO2, OH, O2(1Δ), and the main reaction product H2O. Calculation results that simulate experimental data on the ignition induction time measurements in the hydrogen oxygen mixtures behind reflected shock waves by the methods of absorption spectroscopy (monitoring the OH(2Π) radical) and emission spectroscopy (monitoring the OH*(2Σ+) radical) at temperatures of 1000 < T < 1300 K and pressures p < 3 atm are compared with experimental data and analyzed. It has been shown that the vibrational nonequilibrium determines the mechanism and rate of the process as a whole. The self-heating effect in diluted reacting mixtures at concentrations of the reacting additive ≤5% is demonstrated and discussed.