Calculations and measurements on the flow in unconfined detonation

Abstract

Abstract In this work a comparison is made between measured and calculated flows in axisymmetric detonations based on the axial density profile in the detonation, the shockfront radius of curvature of the detonation, and the reaction zone length. Measurements were made using flash radiography, optical photography, and electromagnetic particle velocity gauging in a commercial air-sensitised emulsion explosive at two voidages, each at two charge diameters. Calculations were performed using the alternative approaches of slightly divergent flow theory and a finite element Lagrangian hydrocode. Chemical reaction rate models in the calculations were parameterised against the measured unconfined detonation velocity charge diameter effect. The result of the study was that both modelling techniques gave good agreement with available experimental data, though the slightly divergent flow model was more accurate in the region close to the shock. It has also been demonstrated that providing the two approaches had been carefully calibrated, the agreement between them was not sensitive to the form of the models used.