Quantification of the perturbations in an explosive gas cloud during expansion using edge tracking and image processing.

The expansion of explosively driven product gases from perturbed C-4 spheres was investigated using high-speed photography and image processing. Spherical charges constructed of 105 g and 880 g of C-4 were used as explosive sources. Each mass explosive charge was tested in three surface geometry variants: baseline smooth, perturbed with 10/π cycles/rad ripples, and perturbed with 20/π cycles/rad ripples. Each test sample was initiated using RP-83 EBW detonators and the explosion was recorded using a Shimadzu HPV-X2 camera. The high-speed video frames were then processed to assemble digital streak images using various streak angles. Radial expansion velocities were extracted from binarized frames. The perturbations on the spheres translated to ripples on the gas clouds for both sphere sizes with the initial perturbations dominating early time gas expansion, resulting in distinct regions of faster and slower radial expansion. For the smooth samples, the edge of the fireball had no discernable structure to its turbulence. At 10/π cycles/rad, the surface of the fireball began to expand noticeably faster where perturbations were initially present. The 20/π cycles/rad samples also displayed faster local expansion at perturbation areas albeit with less clear distinction between ripples than for the 10/π cycles/rad samples.