Influence of overdriven detonation on the energy release of aluminized explosives in underwater explosion

This study investigates the deformation characteristics of a ring-stiffened cylindrical shell induced by shock waves and coalesced bubbles in double-charge underwater explosions. A numerical model for coupling underwater multi-point explosion loads with the cylindrical shell is established by the Arbitrary Lagrange Euler method, and underwater explosion experiments with double charges are also conducted. The numerical model's effectiveness is validated by comparing shock wave superposition characteristics, bubble coalescence processes, and bubble pulsation periods with the experimental results. Based on the numerical model, the influences of detonation intervals and layout angles of charge on shock wave superposition effects, temporal and spatial distribution characteristics of shock waves, and the evolution process of coalesced bubbles in underwater explosions with double charges are explored. Additionally, the deformation characteristics of cylindrical shells induced by shock waves and coalesced bubbles for double charges with different detonation intervals and layout angles of charge are analyzed. The results indicate that double charges can induce more substantial deformation on the cylindrical shell at a specific detonation interval than a single charge with equal total mass. During the shock wave phase, the cylindrical shell's deformation decreases nonlinearly with an increased layout angle. Conversely, during the bubble load phase, the deformation of the cylindrical shell shows an approximately linear decrease with an increase in layout angle. A critical angle exists, below which the impact of double charges on the cylindrical shell is more substantial when detonated with an interval than simultaneous detonation.

Deformation characteristics of a ring-stiffened cylindrical shell induced by shock waves and coalesced bubbles in double-charge underwater explosions

Zhang,

Liu,

Wang

et al. 2024

Theoretical analysis and validation of the detonation wave interaction based on an overdriven detonation

Liu,

Bai

et al. 2024

The oblique collision and reflection of a detonation wave can lead to extremely high pressure and considerable dynamic load mixing in the resulting product, which has been a focus of research in detonation and defense applications. In this paper, the relationships among wave velocity, mass velocity, pressure, and the specific volume of detonation products (DPs) under overdriven detonation (ODD) conditions are analyzed. Additionally, the equations of state (EOS) of the ODD are calibrated by using real-coded genetic algorithms combined with experimental Hugoniot strong detonation data, and the effects of different DPs on pressure accuracy are assessed. Accordingly, a dynamic evolution model of detonation wave interactions in a collision zone is established, and theoretical calculations of regular and Mach reflections occurring after the interactions of typical condensed explosive [such as PBX9501 (95% HMX, 2.5% Estane, 2.5% BDNPA/F)] detonation waves are carried out. The results show that the overpressure Hugoniot data and the isentropic expansion line can be better fitted by using the JWL (Jones–Wilkins–Lee) + γ equation than other EOSs, and the deviation of the calculated pressure and the height of the Mach stem from the experimental value is within 5%. Additionally, a formula is derived for the slow-variable function k(ξ) by combining the improved Whitham method and the JWL + γ EOS, and a propagation law is obtained for the detonation wave interaction.

Evolution of unstable explosion shock wave: Generation and transformation

Wang,

Jiao,

Pan

et al. 2024

We present our discovery of unstable shock trains induced by transmission of unsteady detonation wave with electromagnetic and optical measurements. It reveals that transmission of explosion shock wave is essentially a transfer of state between matter with high energy densities and disturbed medium, and the wave structure depends on the uniformity of energy densities. The generation of transmitted shock wave differs generation of shock wave in the piston problem. This study could form theoretical and experimental basis of unsteady shock wave structure and foster further understanding the mechanism for generation of shock wave.