Influence of Charge Shape and Point of Detonation on Blast-Resistant Design

TLDR

Technical manuals and standards provide charts for computing incident and reflected peak overpressures and scaled impulses from high‑explosive detonations, with design values reported for spherical free‑air and hemispherical surface bursts as functions of scaled distance and angle of incidence for centrally detonated charges. This study aims to characterize how charge shape, orientation, and point of detonation influence free‑field incident overpressures and impulses. Using a verified and validated CFD code, the authors analyze cylindrical charges of varying aspect ratios and masses and compare the results to a baseline spherical charge. In the near and midfield, charge shape and detonation point markedly affect peak overpressure and impulse relative to a centrally detonated spherical charge of the same mass, yet beyond a scaled distance of 3 m kg⁻¹/³ the effect can be ignored for impulse‑based design.

Abstract

Charts in technical manuals and standards of practice can be used to compute incident and reflected peak overpressures and scaled impulses generated by a detonation of a high explosive. Design values are reported for spherical free-air bursts and hemispherical surface bursts as a function of scaled distance and angle of incidence, where the charges are detonated at the center of the sphere. This paper describes a numerical study with a verified and validated computational fluid dynamics code that characterizes the influence of charge shape, charge orientation, and the point of detonation within the charge on free-field incident overpressures and impulses. Analyses are performed with cylindrical charges of different aspect ratios and masses, and results are compared with those of a baseline analysis of a spherical charge. In the near field and midfield, charge shape and point of detonation affect the peak overpressure and impulse, providing values that are significantly different from those associated with a central detonation of a spherical charge of the same mass. The effect of charge shape and point of detonation can be ignored, for the purpose of a design based on impulse, at scaled distance greater than 3 m/kg1/3.