Imaging Detonations of Explosives

Using high-speed camera pyrometers to measure and map fireball/shock expansion velocities.

Army Research Laboratory, Aberdeen Proving Ground, Maryland

An effort has been made within the US Army Research Laboratory (ARL) to extract quantitative information on explosive performance from high-speed imaging of explosions. Explosive fireball surface temperatures are measured using imaging pyrometry (2-color 2-camera imaging pyrometer; full-color single-camera imaging pyrometer). Framing cameras are synchronized with pulsed laser illumination to measure fireball/shock expansion velocities, enabling calculation of peak air-shock pressures. Multicamera filtering at different wavelengths enables visualization of light emission by some reactant species participating in energy release during an explosion. Measurement of incident and reflected shock velocities is used to calculate shock energy on a target.

Results of these measurements are used to construct maps of temperature, pressure, reactant species, and shock energy on a target. This information is valuable to evaluate explosive performance, models of performance, and barriers designed to enhance protection and survivability. These techniques and instruments were developed, in part, to improve productivity by lowering testing costs, allowing a single event to yield temperature, pressure, chemical species, and performance data.