The influence of diamond–graphite ratio on the calculation of detonation performance in VLWR

For high negative oxygen balance explosives, the phase state of solid product carbon will affect the detonation performance parameters of CJ and energy release process. The description of the solid carbon by the Viral theory-based VLWR thermodynamic code only allows the selection of single-phase carbon, which does not correspond to the real physical situation. We set up a thermodynamic calculation model that gives the initial graphite/diamond ratio, and by validating the model with experimental data based on the additional graphite and RDX (C3H6O6N6) systems, we found that considering the graphitization process during isentropic expansion, the simulated data can match well with the experimental values, so the mixed-phase model we proposed can describe the more specific morphology of solid detonation product carbon. Also, based on this model, the effect of diamond/graphite ratio on the detonation performance of negative oxygen explosives TNT (C7H5O6N3), TATB (C6H6O6N6) and HNS(C14H6O12N6) was investigated, and the most probable diamond percentage was reverse calibrated by experimentally measured detonation performance parameters. The component and heat of detonation at the freeze temperature of 1500–1800 K were calculated at this ratio. Finally, the pressure P-volume V relationship for the isentropic expansion of TNT and HMX (C4H8O8N8) was calculated, the JWL equation of state (EOS) was fitted and the reduction of internal energy was calculated. The impact of the diamond/graphite ratio on the energy release of the isentropic expansion zone was investigated.