Correlation Mechanism Between Phase Evolution Of Condensed Carbon And Energy Release During Explosive Detonation

In this paper,aiming at the coupling behavior of the non-equilibrium effect of the condensed phase carbon of the explosive detonation product in the detonation process and the energy release of the explosive,the mixed-phase state calculation model based on the thermodynamic code VLWR is improved,and the kinetic process simulation of Shaw-Johnson is introduced,the research on the phase state and evolution law of condensed carbon in the detonation products was carried out.The specific research work is as follows:Study the state of solid products based on VINET equation of state,including the introduction of universal equation of state VINET and its related applications based on VLWR thermodynamic code(evaluation of detonation performance parameters,evaluation of work ability,theoretical calculation of reaction zone width).Based on the VLWR thermodynamic code,the universal solid state equation VINET is introduced,and the reliability of the VINET state equation in describing the solid shock compression data is verified by calibrating the complete state equation of the related material.In order to more truly reflect the compressibility of nanocarbons in the extreme high-temperature and high-pressure environment of the detonation process,the SVM(support vector machine)was used to optimize the input parameters and the detonation performance of several explosives with different densities was calculated,which was compared with the experimental results.The application of the thermodynamic code using the improved VINET solid-state equation in the study of the working ability of explosives was investigated,the relationship between the thermodynamic parameters of different explosives in the isentropic state was calculated,and the universal Cooper curve and JWL equation of state parameters used to describe the isentropic expansion are fitted.The LS-DYNA code is used to numerically simulate the cylinder test of explosives,and it is verified that the improved algorithm has better advantages in describing the working ability of explosives.The chemical reaction rate function is introduced into the thermodynamic code of the improved VINET solid state equation,and a theoretical calculation method that can describe the pressure history in the reaction zone of the explosive is established.The mixed phase model is built and applied to study the related properties of explosives.Considering the multiphase composition of carbon in the chemical reaction zone,a thermodynamic calculation model was established based on the COWAN equation of state to give the initial ratio of graphite/diamond,and the model was verified by experimental data based on external graphite and RDX systems.Based on this model,the effect of diamond/graphite ratio on the detonation performance of negative oxygen explosives was studied,and the most probable diamond ratio was demarcated by the detonation performance parameters measured experimentally.At this ratio,the composition at the condensation temperature of 1500-1 800K at isentropic expansion was calculated,the relationship between the heat of explosion and the thermodynamic parameters of the product were calculated,the JWL equation of state was fitted,and the reduction in internal energy was calculated.Compared with BKW,BKWR and JCZ3,the accuracy of detonation energy calculated by VLWR using the mixed ideal model was greatly improved.The calculation of the heat of explosion and the detonation energy of the isentropic expansion region further verifies the validity of the mixed-phase model.The mixed-state potential parameters are constructed to study the influence of mixed-phase on reaction zone.Based on the equilibrium solid state equation of state VINET,considering the mixing law of multiphase carbon components,the matching relationship between the solid state product equation parameters and thermodynamic potential parameters of the equivalent system and the phase mixing system is constructed by means of nonlinear fitting,which realizes the effective simplification equivalence of the nonequilibrium multiphase mixing system and overcomes the most possible single phase screening problem based on the principle of minimum free energy,the thermodynamic state change relationship of the product under different carbon phase composition of CJ state was obtained.Photon Doppler velocimetry(PDV)was used to measure the interfacial particle velocity to study the effect of carbon evolution difference on the structure of explosive reaction zone.For high negative oxygen balance explosives,intramolecular carbon blur the inflection point at the junction of the reaction and expansion zones of the particle velocity at the explosive interface,resulting in the backward movement of reaction end point,which may be related to the condensation and energy release effect of carbon;and the endothermicity of the added graphite reduces the temperature and prolongs the chemical reaction zone.The effect of carbon evolution difference on energy release in expansion zone was studied.Combined with Shaw-Johnson model and JWLM equation of state simulation,based on the phenomenological chemical reaction model of explosives,considering the kinetic process of carbon condensation,the kinetic model is studied.Combined with the state change relationship of the internal energy of condensed carbon products at different times and the energy release characteristics,the correlation mechanism between the carbon coagulation process and the energy release process is analyzed by combining the thermodynamic calculation with the test results of driving thin flyer(the thickness is equivalent to the width of the reaction zone,and the thickness is much greater than the width of the reaction zone)through dynamic simulation,that is the phase and condensation process of carbon will affect the energy release and working ability of explosives.