The gas product of detonation of a secondary explosive can be described by a liquid equation of state that describes interaction between the molecules as strong repulsive and all outer heat motions of the molecule as free translations. The solid product carbon can be described as the rigid body. Then, a two-phase repulsive-translation equation of state of detonation product (two-phase R-T EOS for short) has been obtained. The two-phase R-T EOS using a known isentropic composed of two sections and through the CJ point as a reference curve has been named two-phase R-T (k, γ) EOS and used to estimate the detonation and strong-detonation parameters of some explosives. The theory and experiment values of detonation parameters are in good agreement. The expressions of specific energy and pressure that describe strong repulsive interaction between molecules (cold specific energy and cold pressure for short) are necessary in order to estimate detonation temperature directly and conveniently. The expressions of cold specific energy and cold pressure with uncertain parameters A, m, n and l were obtained with reference to repulsive terms of the Mores and Mie potential expressions, then the two-phase R-T EOS characterized by the cold specific energy and the cold pressure was named two-phase R-T (A, m, n, l) EOS. With experimental {D, ρ₀} data of TNT, the parameters n and l were determined, namely, n=1 and l=1/3, because the error between calculated and experimental data is minimum (0.59%) in this case. The two-phase R-T (A, m, n, l) EOS of n=1 and l=1/3 was named two-phase R-T (A, m) EOS for short. A test of the two-phase R-T (A, m) EOS with the experimental parameters of strong detonation for Nitromethane was performed. The average error between calculated and experimental data of detonation velocity and temperature are respectively 0.36% and 203 K. The latter can be explained as without consideration of melting of graphite. Therefore a conclusion that the two-phase R-T (A, m) EOS is a proper equation of state of detonation product was obtained.

equation of state  /  explosive  /  detonation