Abstract:

The high temperature oxidative mechanism of a new four-component RP-3 surrogate fuel model was investigated using the ReaxFF MD method. The evolution of the fuel molecules, oxygen, C₂H₄, and ?CH₃, and the underlying reactions, were obtained by systematic analysis of the simulation trajectories with the aid of VARxMD, a unique tool for ReaxFF MD reaction analysis developed by the authors′ group. The simulated consumption of fuel and oxygen, as well as the amount of ethylene and methyl radicals, in RP-3 oxidation are of the same magnitude in the ReaxFF MD simulations as that predicted by CHEMKIN under the same temperature and initial pressure conditions. Based on the chemical structures of all the species and the full set of reactions obtained, the detailed mechanisms observed in the simulations broadly agree with the previous literature. The first reactions of the fuel molecules can be categorized into H-abstraction and internal scission, with the latter dominating under various temperature conditions. Observation and statistical analysis of the oxygen reactions reveal that small species of C₁-C₃ are involved in a relatively large proportion, which may allow the simplification of the reaction mechanism. A reaction network for RP-3 oxidation at high temperature is obtained through the analysis of the reaction mechanisms. This work demonstrates that the ReaxFF MD method, combined with the unique reaction analysis capability of VARxMD, provides useful insights into the mechanism of fuel combustion and should aid the construction of combustion mechanism libraries.

Key words: RP-3, Reaction mechanism, ReaxFF MD, Oxidation, Molecular simulation