Contributions of Experimental Data Obtained in Concentrated Mixtures to Kinetic Studies: Application to Monomethylhydrazine Pyrolysis

Experimental, numerical,
and theoretical studies are performed
to understand the explosive thermal decomposition of monomethylhydrazine/argon
mixtures. Ignition delays of concentrated MMH/Ar mixtures (20–30%)
have been measured behind a reflected shock wave around 1000 K and
1 atm. Although several detailed chemical kinetic models have predictive
abilities for diluted and highly diluted mixtures, none of them showed
predictive for concentrated mixtures. A new kinetic model is proposed,
in which numerous rate constants and thermochemical data are reassessed
based on theoretical calculations, with the purpose to determine whether,
or to what extent, trends derived from diluted or highly diluted MMH/Ar
mixtures can explain observations in concentrated MMH mixtures. The
present kinetic model is found to predict speciation experimental
profiles in diluted MMH/Ar mixtures and is a significant improvement
in predicting the induction delays of concentrated MMH/Ar mixtures.