Study On Theory And Application Of State Equation Of Explosive Detonation

In this paper, we introduce an equation of state(EOS) of gaseous detonaion products of explosives named VHL(Viral-Han-Long) for improving the shortage of VLW EOS in describing the gasoeous thermodynamical state at high temperature and middle-high pressure. We describe the thermodynamical state of gaseous component of detonation products using VHL EOS and study the application of VHL EOS in three aspects of explosives:predicting detonation parameters, assessing doing work ability and ascertaining detonation reaction zone(DRZ). The details are shown as follow:Based on high temperature and middle-high pressure thermodynamical data of non-pole CH4, we firstly discuss the accuracy when VLW EOS is used to discribe the thermodynamical state of CH4. Then we put forward a new EOS named VHL(Viral-Han-Long) to accurately discribe the thermodynamical state of CH4, in which the former four viral coefficients are in agreement with the theoretical calculation and the higher viral coefficents are simplyfied as a combination function. According to correspond principle, we realize the accurate discription of other non-pole or weak-pole deotonation gaseous components (CO2、CO、O2、N2、H2) by Lennard-Jones(L-J) potential function at high temperature and middle-high pressure. For strong-pole detonation product component H2O, we put forward a temperature-related L-J potential function to accurately discribe the thermodynamical state of H2O.Based on VHL EOS for detonation gaseous products and Cowan EOS for detonation solid carbon product, we successfully compile a thermodynamical code named VHL to calculate the detonation parameters of explosives, in which we apply the minimum of Gibbs free energy and CJ theory. All detonation gaseous products are equal to single component by mixing rule. There are three types parameters for solid carbon phases(graphite, diamond and liquid-like) selected by the minimized Gibbs free energy. Using thermodynamical code VHL, we calculate the detonation parameters of typical explosives (PETN, RDX and TNT) with wide density and the detonation temperature of thirteen explosives with known experimental data and the components of detonation products for typical explosives.In order to assess the availability of thermodynamical code VHL using in doing work ability, we firstly calculate the JWL EOS parameters of TNT and HMX based explosvie under the iso-entropy condition(S-SCJ). Then we use hydrodynamical code LS-DYNA to simulate three experiments:the cylinder test of TNT, shock wave orbit test of TNT in the water and radial expansion orbit of the surface between detonation product of HMX based explosive and water. The calculation result reveal that the thermodynamical code VHL can effectly characterize the thermodyanmical state of detonation products. Combined hydrodynamical code, we can accurately assess the doing work capacity of explosives.In order to avoid the arbitrary judgement of CJ point in the study of the DRZ of explosives, we put forward a available method with the experiment measurement and thermodynamical calculation. Firstly, we need measure the velocity history of the surface between explsive and PMMA window using a displacement interferometer system for any reflector system(DISAR). Then, we calculate the iso-entropy curve expressed as the relationship pressure and particle velocity. Next, combined the PMMA hugoniot curve, we judge the velocity value of the cross point between iso-entropy curve and PMMA hugoniot curve. Finally, we can find the matched velocity from the measured velocity history and ensure the chemical reaction time in the explosive DRZ. Based on ZND model, the EOS of unreactive explosive and chemical reaction rate related pressure, we put forward a theoretical calculation method to model the pressure history and the variation of detonation product components in the DRZ of explosives.