Research On The Structure Of The Detonation Reaction Zone Of Condensed Explosives

At the steady detonation state of explosives,chemical reaction takes place behind the wave front where is called the reaction zone.The data of reaction zone of different explosives is of great importance in the numerical modeling and the relative equipment design.As the reaction zone involves the fast and complex interaction between the chemical release and the fluid,it is necessary to measure the interface velocity with testing method of high precision to investigate the reaction zone.We have conducted both experimental measurements and numerical modeling to investigate the reaction zone of typical HMX-based and insensitive explosives.First,the interface velocity of the HMX-based explosive JOB-9003 was measured with the photon Doppler velocimetry(PDV).An obvious turning point can be found on the curve of the interface velocity,we overlap the interface velocity of different length of explosives to tell where the CJ point is located.The reaction time of the JOB-9003 is(25±2)ns and the according length of reaction zone is(0.169±0.014)mm.The CJ pressure is calculated with the resistance matching formula.The CJ pressure of JOB-9003 is(35.4 ± 1.3)GPa,and the pressure at the Von Neumann spike is(47.5±1.3)GPa.The interface velocity of the TATB-based explosive JB-9014 was also measured with PDV.JB-9014 is different from sensitive explosive that it's TATB-based,and its chemical reaction is relatively slow.The measured wave profile proceeds down from the reaction zone to the zone of Taylor rarefaction wave smoothly,and no obvious turning point can be found as the CJ point on the interface velocity curve.By overlapping the particle velocity curve of different lengths of explosives,we obtained a bifurcation as the C.J point.The reaction time and the reaction zone length are determined in this way.Finally,we figured out the reaction time of the JB-9014 is(0.266±0.02)ns,and the according length of reaction zone is(1.54±0.2)mm.The CJ pressure of JB-9014 is(27.3±0.7)GPa.One dimensional steady numerical solutions were conducted on the JOB-9003 and JB-9014 explosives.The results of their reaction time and reaction zone length are in good accordance with the results from laser interferometric experiments.One dimensional non-steady simulations were also conducted.The interface velocity obtained is also in great accordance with experiments.in the simulation results,an obvious turning point can be observed on the interface velocity curve of the HMX-based explosive,which is to the opposite of the case of insensitive explosives.The frozen sonic point satisfying the CJ relationship was also determined with the simulation.It was turned out that the frozen sonic point of the insensitive explosive is located ahead of the end of reaction,in other words,there is still a part of energy released after the CJ state.