Experimental and numerical analysis of dynamic action evolution of blast shock wave and detonation gas

Abstract

The action mechanism of blast shock wave and detonation gas in rock blasting remains unclear. This article attempts to reveal the action mechanism of blast shock wave and detonation gas through high-speed schlieren system, overpressure test system and AUTODYN numerical simulation analysis. 5 cartridges under different explosive types and charge structures were designed, and the dynamic action evolution of detonation products can be visualized from schlieren photos. The action change of blast shock wave and detonation gas in the flow field were compared under the said five conditions. The numerical simulation results were compared with the schlieren experiment results, and the detonation wave process in explosives was reversely deduced. The results showed: the blast shock wave initially expand along with the detonation gas, both propagate outwardly around the point of detonation in a spherical shape. During propagation, the blast shock wave is gradually separated from the detonation gas, and the blast shock wave propagates at a higher velocity compared with the detonation gas. In the scenarios of different charge structures, the features for which the blast shock wave is separated from the detonation gas are varied, the time of separation will shorten as the constraining effect of the cartridge shell intensifies. In the scenarios of different explosive types, the wave patterns of shock wave and detonation gas are essentially the same. However, the velocity and pressure change of shock wave and detonation wave may deviate in the course of propagation, due to different physical and mechanical parameters of explosive materials. In the presence of slot, shock wave and detonation gas will first propagate outwardly from the slot, then the flow is carried out in the other direction, and the pressure and speed in the incision direction will increase, the energy along the slot direction is concentrated and the tube wall is first damaged, resulting in the effect of directional damage. In the numerical simulation, the fluctuation pattern and schear experimental results of explosion shock wave and explosion gas are more consistent in morphology.

Keywords

• blast shock wave
• detonation gas
• high-speed schlieren
• dynamic evolution
• autodyn