Chemical Kinetic Model for Monomethylhydrazine/Nitrogen Tetroxide Gas-Phase Combustion and Hypergolic Ignition

A detailed kinetic model devoted to the gas phase hypergolic ignition of MMH/NTO mixtures below 298 K and their combustion above 1000 K is presented in this study. It consists of 403 equilibrated reactions among 82 species. This mechanism has been confronted with theoretical data available in the literature. The agreement between theory and predictions is found to be good. Important reactions for ignition at low initial temperature and pressure have been identified through sensitivity analyses. Two competing pathways can explain hypergolic ignition at low temperature. The formation of molecular preignition products is shown to promote the ignition. This conclusion was unexpected, as the formation of these products was generally considered to inhibit the ignition, by reactant consumption. Important reactions for combustion above 1000 K have been preliminarily identified. Some reactions are important both for low-temperature ignition and combustion, whereas some others are important either for ignition only or combustion only. The study is focused on the need for three reduced kinetic models.