Optical Characterization of Large Caliber Muzzle Blast Waves

High‐speed, 1,600 Hz, visible imagery of the blast wave from 147 firings of a 152 mm howitzer were observed for three different propellant charges. Blast wave trajectories were determined at 0.5–13 m from the muzzle exit, yielding initial velocities of Mach 3–4 that decayed to near acoustic within the imager field of view. A piecewise treatment of the Taylor‐Sedov point blast model was sufficient to describe the trajectories with an average error of 0.1 m. The trajectories were consistent with a three‐dimensional expansion and constant rate of energy release. A Constant Breech Pressure gun model was used to estimate total energy of the muzzle flow, and the efficiency of depositing energy into the blast wave was 18–24 %. Plume temperatures of approximately 980–1,210 K were estimated by partitioning energy and were correlated with likelihood of plume combustion. Classification of charge type based on energy deposition rate was modest, characterized by a ratio of between‐class to within‐class variance of 1.3, for the very similar events.