Experimental observation and modelling of contained detonations of PE4: what is the influence of afterburn?

Accurate modelling of free-field detonations needs to account for both the initial energy release and gas generation, and the subsequent reaction of the initial detonation products with external oxygen. An upper limit for the extent of ‘afterburn’ can be ascertained from comparison of contained blasts in reactive (air) and inert (nitrogen) bath gases. The peak quasistatic pressures (QSP) and the gas phase products were determined in a 0.276 m3 blast chamber following detonations of the plastic explosive PE4. The experimental observations were compared to predictions based on standard models, CEA and EXPLO5. The best agreement between models and experiment, for both products and QSPs, was obtained from the Springall-Roberts treatment of detonation products in nitrogen, and complete combustion of these in air.