<title>Photographic study of channel effect in emulsion explosives using a high-speed framing camera</title>

Abstract

The precursor air shock wave (PAS), which is propagating ahead of the detonation front in air channel, precompresses and desensitizes the unreacted explosive charges. In some conditions, the PAS causes detonation failure. This phenomenon is known as the channel effect. To investigate the mechanism of the channel effect in emulsion explosives, some experimental works have been carried out using high-speed framing camera. The results of photographic observation at the first experiments demonstrated that the difference between PAS velocity and detonation velocity was the primary factor for the channel effect. It is assumed that the decrease of the PAS velocity can prevent the channel effect. The increase of surface roughness of inner wall was adopted to decrease the PAS velocity. Some experiments were conducted to investigate the effects of surface roughness on the PAS velocity and the detonation propagation. Photographic observations were performed using rectangular tubes with sandpaper on inner ceiling wall to simulate surface roughness under various conditions. The experimental results indicate that the increase of surface roughness reduces the PAS velocity and prevents detonation failure. It is concluded that the surface roughness of wall has a great influence on detonation propagation in emulsion explosive.