Enhancement of blast wave parameters due to shock focusing from multiple simultaneously detonated charges

Abstract

With the increase of terrorist attacks over the past decades, many engineering societies have started issuing design guides to calculate blast loads on structures. While such guides can be successfully used to assess blast loads due to single detonations, the effects of multiple detonations are often overlooked. In this research, the enhancement in blast parameters resulting from simultaneously detonating multiple charges is investigated, emphasising the interaction of blast waves with narrow targets. A parametric CFD study using the finite volume code Viper::Blast was performed where the number of charges, their arrangement, and the scaled stand-off distances were changed. It is found that, when detonated simultaneously, multiple charges return much higher pressure and impulse values compared to an equivalent single charge. Moreover, an arced arrangement of multiple charges is more efficient than a flat arrangement in enhancing blast wave parameters. Such enhancement is beneficial in scenarios involving demolition. Approximate methods to compute blast wave parameters from multiple simultaneously detonated spherical charges are presented in this study, where pressure and impulse from multiple charges can be computed by only knowing the parameters resulting from an equivalent single charge.

Experimental and simulation study on blast loads of cylindrical Shells

“…Although reflected waves and secondary shocks meet in Figure 4(f) and (g), they continue to spread along the original trajectory and curvature of blast waves, it seems that the gas did not collide, this phenomenon was also clearly captured in previous experiments (Zaghloul et al, 2021; Zheng et al, 2021). It can be seen from the pressure distribution in Figure 10(c), this phenomenon can be explained as two waves merge to form a high-pressure area and then spread to the surroundings with less energy loss.…”

“…For the cylindrical charges (Fan et al, 2022; Gao et al, 2021; Langran-Wheeler et al, 2021) commonly used in the military, blast waves were divided into end waves, side waves, and bridge waves according to the direction of charges, which has obvious directionality. The effects of charge shape (Artero-Guerrero et al, 2017) and detonation point (Hu et al, 2018; Zaghloul et al, 2021; Zuo et al, 2020; Xiao et al, 2020) should be quantified to reduce the dispersion of blast loads, which in turn guides the structural design.…”

Blast loads and variability on cylindrical shells under different charge orientations

“…5 b), finally, the reflected wave collides with the secondary shock wave (Fig. 5 c) to form a high-pressure area and bounce back 15 , 34 , 35 , the two waves seem to remain in their original trajectories without interference (Fig. 5 d).…”

A branching algorithm to reduce computational time of batch models: Application for blast analyses

“…This is firstly because the results obtained from the analysis are not used in forming the conclusions of this article, with the focus instead being placed on the ability of the proposed method to save computation time. It is however important for the obtained results to be representative of the explosive scenario and since Viper::Blast is a tool founded upon established work published by Rose (2001) and Wada and Liou (1997), it is chosen approach for various studies including an air blast variability analysis conducted by Marks et al (2021) and the evaluation of multiple simultaneously detonated charges by Zaghloul et al (2021). This gives confidence that the observed parameters will be characteristic of an explosive test and therefore with progressive simulation time steps that represent typical blast analyses.…”