Equation of state of explosion products on the basis of a modified van der Waals model

A semi-empirical model is proposed for the equation of state of high explosives in a range of pressures and temperatures typical of detonation processes. A possibility of formation of solid phases (e.g., graphite or diamond) in the gas is implied. The model can be used to calculate all thermodynamic quantities for arbitrary molecular compositions and to calculate the thermodynamically equilibrium molecular (and phase) composition. An iterative scheme of calculations is proposed. The model contains several empirical functions whose form can be changed without violating the overall calculation scheme. A particular set of these functions is considered as an illustration. Some results calculated for a number of high explosives containing four elements (C, H, N, and O) are presented. The calculated results are compared with available experimental data.