DEVELOPMENT OF GAS-PHASE REACTION-MECHANISMS FOR NITRAMINE COMBUSTION

A methodology for developing gas-phase reaction mechanisms for nitrami ne propellants is discussed. Examples of Fundamental kinetic experimen ts and detailed modeling calculations are given that emphasize a hiera rchical construction procedure for both the types of experiments neces sary for collecting kinetic: data and the specific chemical submodels that need to be studied. In particular, three kinetic submodels of inc reasing complexity are described with selected results from flow react or experiments. With kinetic data generated from these experiments and others, chemical submodels are developed and validated by comparison of model predictions with experimental measurements using reaction flu x and sensitivity analyses to guide the process. Collectively, the sub models, validated over the entire range of experimentally studied cond itions, are assembled to form the gasphase nitramine combustion mechan ism. Because of the nature of the developmental procedure, e.g,, the n ecessity for different types of experiments, ranging from ''microscopi c'' measurements of isolated reaction rate constants to ''macroscopic' ' studies on kinetic mechanisms in flames, the process is inherently i terative. As an example of this iterative procedure, numerical results are presented on the ignition behavior of hexahydro-1,3,5-trinitro-1, 3,5-triazine (RDX) after updating a previously developed model with re cent results from submodel validation experiments, These results show changes in the pathways of many secondary species involved in RDX deco mposition.