New Method For Predicting The Combustion Characteristics Of Nitramine Chemicals Using Multi-Component Surrogate Fuels

Nitramine is one kind of solid-phase explosive chemicals with nitrogen-nitro?N-NO2?functional group.Which is widely used for launching gun tube weapon and solid rockets by virtue of its ability to release large amounts of gas and heat during combustion.The combustion reaction of nitramine belongs to three-phase reaction with gas-solid-liquid system,especially existing the multiphase coupling phenomenon in the condensed layer,thereby resulting in predicting inaccurately the combustion characteristics of nitramine chemicals based on previous combustion model.According to the previous research that the macroscopic combustion characteristics of gaseous fuels depend on the intermediates,a multi-component gas-phase surrogate fuel model was successfully established for accurately simulating the high-temperature combustion characteristics of nitramine chemicals,through the pyrolysis experiment of nitramine,and the traceability study of multi-component surrogate fuel on basis of the distribution of pyrolysis intermediates.Not only has it effectively avoided the research dilemma of the condensed reaction zone,but also propose a new method for simulating the combustion characteristics of solid-phase hazardous chemicals.Firstly,the important reaction intermediates and groups in the high-temperature reaction flow field of RDX,HMX and CL-20 were experimental analyzed and qualitatively confirmed.Some important intermediates and groups such as HCN,HNO,HCO,CH₂O,NO,NO₂,N₂O,NH,NH₂ and NCO are verified in the pyrolysis gaseous products of RDX,HMX and CL-20 by using TG-DSC-FTIR-MS.Secondly,a multi-component gas-phase surrogate fuel model with approximately intermediates and groups distribution was established based on the results of qualitatively confirmed reaction intermediates and groups.Referring to the previous researches on the reaction mechanism of low molecular weight gas-phase mixed fuel,five gaseous fuels,including CH₄,C₂H₆,C₃H₈,C₂H₄ and NH₃ were picked out as the components of multi-component surrogate fuel relying on the similarity criterion of important intermediates distribution.The relative molar percentage of the species in the multi-component surrogate fuel are characterized by the sensible enthalpy change parameter of the component within the kinetic controlled pyrolysis temperature range.And considering the importance of N-containing pyrolysis intermediates and groups in the actual combustion reaction of the nitramine,the NH₃component in the RDX,HMX and CL-20 multi-component surrogate fuel models was corrected according to the N-element conservation relationship.Finally,the multi-component gas-phase surrogate fuel model was used to simulate the high-temperature combustion characteristics of RDX,HMX and CL-20,and the results were compared with previous experimental data.The maximum differences of flame temperature between the aforementioned results and the previous experimental data are 5.15%,6.04%and4.58%,respectively,under the condition of standard atmosphere.In summary,the multi-component gas-phase surrogate fuel model established in the work can be used for accurately simulating the high-temperature combustion characteristics of nitramine chemicals such as RDX,HMX and CL-20.