FIG. 3.
High speed Schlieren imaging of the blast pressure wave from the gun barrel tip reveals Mach disk formation in the wake of the blast (A), indicating that the peak pressure output moves at supersonic speed. Measurements of the angle formed by the intercepting shock and the jet boundary, known as the Mach angle (B), were used to calculate the speed of the blast wave as it leaves the blast gun nozzle.44 Image A is an enlarged and higher contrast view of the original image in B, shown for easier visualization of the Mach disks and other blast features.