Nonideal regimes of deflagration and detonation of black powder

Comparison of the Explosion Thermodynamics of TNT and Black Powder Using Le Chatelier Diagrams

“…As for TNT, under the ideal gas assumption, the primary products are iso‐entropically expanded to 298 K. The final value of explosion energy is Δ H exp =−3045 J per g BP , which is in relatively good agreement with the values of Δ H exp =−2700 J per g BP and Δ H exp =−2900 J per g BP , respectively, given by Fedoroff and Sheffield 29 or Ermolaev et al. 28 if considering that wood char (willow char is used in practice) has a heat of formation of about Δ H g =−200 J per g C (Dasappa et al. 30, e.g.…”

“…That could be also the simple explanation for the unexpected dramatic explosion of large amounts of low‐energetic (non‐detonative) pyrotechnics in the EU project CHAF 40, where totally confined or partially confined explosion experiments were performed. The result is also important if considering the very low detonability attitude of black powder, as shown by Ermolaev 28.…”

“…That could be also the simple explanation for the unexpected dramatic explosion of large amounts of low‐energetic (non‐detonative) pyrotechnics in the EU project CHAF 40, where totally confined or partially confined explosion experiments were performed. The result is also important if considering the very low detonability attitude of black powder, as shown by Ermolaev 28. For the aims of this work (evaluation of internal energy at standard state, description of afterburning phenomena) the knowledge of thermodynamic properties at CJ is not essential. The use of internal energy calculated at the adiabatic decomposition temperature starting from a given initial density and pressure as calculated by CEA is reliable.…”

“…These aspects are largely analyzed in Ermolaev et al. 28, which conclude on the non‐ideality of black powder explosion, on the great difficulties on detonating black powder compositions and on the absence of deflagration to detonation transition for black powder.…”

“…To this regard, Ermolaev et al. 28 report a calculated CJ temperature of 2633 K, however for very low initial density of black powder (1000 kg m −3 ).…”