DUAN Bao-fu 1,2 , SUN Ke-bin 1,2 , SHEN Shi-zhan 1,2 , HOU Wei 1,2 , GU Li 1,2
Powdery emulsion explosive is a new type of industrial explosive with good performance and wide application. Combustion to detonation (Deflagration to Detonation Transition, DDT) should be studied to ensure production reliability and safety. In this study, powdery emulsion explosive samples with average particle sizes of 92, 130, and 150 ?m were selected as the research objects. Experimental methods were designed to conduct combustion to detonation experiments on beds with different loading densities by using a DDT tube sealing device. Various experimental characteristics of powdery emulsion explosives in DDT were found, and they were different from those of other simple high-energy explosives. When the fiber optic probe was located on the inner wall of the DDT tube, only the velocity signal of the detonation stage was detected. When the fiber optic probe was located at the axis of the explosive bed, the relative complete combustion and detonation velocity signals of the explosive bed were measured. When the DDT tube was placed horizontally, the combustion to detonation phenomenon occurred in all the beds, with the loading density within 0.67–0.89 g/cm3. When the loading density exceeded this range, the combustion of the beds was easily stopped, and the combustion to detonation phenomenon was difficult to occur. When the DDT tube was placed vertically or obliquely, no detonation occurred in the explosive bed with different loading densities, and combustion was propagated to extinguish not far from the ignition head. Only by choosing an appropriate placement method for the DDT tube can the continuous burning of the explosive bed be ensured during the experiment. It indicates that powdery emulsion explosive cannot burn by itself without sufficient external energy support. The position of probe and the placement of DDT tube directly affect the results of DDT experiments.