Reparameterization of the Becker-Kistiakowsky-Wilson equation of state for water-gel explosives

Abstract

This paper describes the results of the reparameterization studies on the Becker-Kistiakowsky-Wilson (BKW) equation of state (EQS) for water-gel explosives. The original set of BKW parameters (α = 0.5, β = 0.1, κ = 11.85, and θ = 400) predicts a higher detonation velocity and detonation pressure and a lower detonation temperature compared with the experimental values for these explosives. Among the several combinations of parameters examined, the following set-α = 0.5, β = 0.1, κ = 8.85, and θ = 1850—is found to give realistic values for the various detonation properties. Moreover, the predicted and the experimental detonation velocities are seen to be in fair agreement. A comparison of the computed and the experimental (obtained from Crawshaw-Jones measurements) fume characteristics shows that (1) inclusion of the wrapper material in the explosive composition increases the concentration of fumes and gives correspondence between the two for products such as CO, H 2, NH 3, and CH 4, (2) the measured NO X concentration is difficult to get in these computations, and (3) calculations of the product compositions for the isentropic expansion of detonation products along the Chapman-Jouguet (C-J) isentrope give freeze-out temperatures in the range of 1000–1800K. These computations were also performed for two ammonium nitrate-fuel oil mixtures and are found to be in good agreement with the experimental data.