Performance prediction of high-energy-density material CL-20 based on FP-CL20 chemical kinetics model

Abstract

The instantaneous high-energy release characteristic of high-energy-density materials (HEDMs) renders them an essential component of high-energy propellants or explosives. Hence, the prediction of performance of HEDMs is of paramount significance for its engineering application. In this paper, using first-principle molecular dynamics approach with multi-scale shock technique, the detonation reaction process of CL-20 is studied, and the detailed chemical reaction kinetics are analyzed. Combining quantum chemical calculation, the first chemical kinetics model (FP-CL20 model) which contains 153 species and 412 elementary reactions is constructed. The pyrolysis and detonation performance of the CL-20 explosive under experimental conditions are predicted by using the FP-CL20 model. Within the framework of the approximation, the agreement of predicted key physical quantities of pyrolysis and detonation for CL-20 with the experimental results is satisfactory. FP-CL20 model also reveals that reaction N₂O+NONO₂+N₂ and CO+NO₂NO+CO₂ play key roles in the formation of N₂ and CO₂ under detonation. While different from detonation, NCO+NON₂+CO₂ and NCO+NO₂CO₂+N₂O are the main reactions for the formation of N₂ and CO₂ under pyrolysis. Within the detonation reaction zone, the oxidation of small molecular N-heterochains (L-NCNCO+OHNCN+HOCO) and small molecular carbon oxides (HOCO+OHCO₂+H₂O) are key reactions that affect the detonation reaction zone time. Our studies offer a novel insight into understanding the pyrolysis and detonation reaction mechanism of CL-20, also paving the way for the construction of chemical kinetics model and the performance prediction of HEDMs.