Influence of longitudinal air gaps within charge structure on the detonation performance of explosives

To investigate the effect of the longitudinal air gap on the detonation performance of HMX-based explosive, direct observation of steel plate deformation and damage under forward and slipping detonation of HMX based explosive was conducted based on the laser illumination combined with the ultra-high speed framing imaging technology. The multi-position optical speed measurement technology was also introduced to continuously measure the speed of steel plate, which enables a multidimensional characterization and quantitative research on steel plate damage under the influence of air gaps. It is found that when the air gap width is 0.05, 0.10 and 0.20 mm, the motion mode of the steel plate changes obviously under the forward detonation. The trend of the center point movement changes from step rising to oblique wave rising, indicating a notable elongation of the lead time of detonation wave. And the steel plate also has an obvious deformation and breakdown. Driven by slipping detonation, the motion patterns across various points of the steel plate are largely uniform, with only marginal variations in the lead time of detonation wave. No significant deformation or rupture of the steel plate is observed. It is considered that the wedge-shaped wave formed by the precursor shock wave and detonation waves is the key to the breakdown of the bottom of steel plate in the case of forward detonation. However, the momentum component of the precursor shock wave and detonation wave acting on the side of steel plate in the case of slipping detonation is small, so that no obvious damage occurs. This article also provides a lot of quantitative data on the deformation of steel plates subjected to longitudinal air gaps, which can provide high-precision experimental data for the related numerical simulations and theoretical analysis work.