Evaluating blast wave overpressure from non‐spherical charges using time of arrival from high‐speed video

Abstract

AbstractScaled distance is used to predict blast wave overpressure surrounding the detonation of a known mass of explosive under the assumption that the charge geometry is spherical. Altering charge geometry from spherical overdrives regions of the blast wave resulting in areas of higher overpressures than predicted by scaled distance calculations. Empirical data can be used to scale the blast wave overpressure to cylindrical charges, but available overpressure data for more complex geometries is not available in published literature. In the present study the time of arrival of the blast wave was measured from high‐speed video and the Rankine‐Hugoniot relationship used to measure blast wave overpressure for varied explosive geometries. The radial overpressure of prismatic charges with cross‐sectional shapes of triangle, rectangle, and 5‐point star isotropic were compared to the radially isotropic overpressure distribution produced by a cylindrical explosive charge. The rectangle produced the highest overpressure measuring 3.5 times that of the cylinder while the triangular charge had the greatest presented surface area and was only overdriven 3.0 times. From the high‐speed video the fireball of detonation products surrounding the star appears significantly overdriven from the internal angle, but this orientation was underdriven at 2.0 meters. The blast wave overpressure downstream from the outside corners of the rectangular and triangular prismatic charges were similar to that of the cylinder at 1.5 meters but trended higher at increasing distance.