Impact of height of burst on fireball expansion in C4 explosions

Studying the interface between explosive product gases and ambient air during an explosion

presents challenges due to turbulent mixing and three-dimensional expansion of the fireball. This

research explores the interface evolution for different near-ground heights of burst. High-speed

cameras captured fireball expansion during the explosion of 880-gram charges of C4 high

explosive. The images were analyzed through a semi-automated image processing routine to

extract the gas interface and ground shock reflection. Pressure gauges in a housing buried flush

with the ground surface measured ground shock interactions. The gauges recorded overpressure

changes affected by burst height and angle of reflection from incident waves. Initial findings

indicate an influence of burst height on fireball development and evolution, as well as ground

shock intensity and distribution. Results are compared to free-air burst of the same C4 charges.