Numerical Study of the Blast Mitigation Effect of the Shape of a Partially Confined Geometry and Scaling of the Blast Wave Strength

Abstract

We conducted a series of numerical simulations to understand the effect of the shape of a partially confined geometry on blast wave strength, including its scaling method. We referred to an explosion of a high explosive in an underground magazine, and the underground magazine model had two sections: a chamber and a passageway. The internal diameter ratio between the chamber and the passageway was the parameter, and a smaller internal diameter ratio led to more impactful mitigation of the blast wave outside. Moreover, we adopted the shock tube theory with a large-area contraction to better understand the blast wave characteristics at the exit. The physical quantities at the exit agreed well with the analytical values applying the shock tube theory. The total energy release rate at the exit is an important factor for determining the blast wave strength, and we validated that the cube root of the total energy release rate of the shocked air at the exit, estimated by the shock tube theory, could scale the blast wave strength outside.