Numerical simulation of normal reflection shock wave of near-surface nuclear explosion

The shock wave of near-surface nuclear explosions is of particular interest due to the wide range of destructive damage and destroy. In this study, the normal reflected shock wave of near-surface nuclear explosion is considered based on the similarity law of explosion. AUTODYN has also been utilized to simulate the reflected shock wave in the air. The numerical simulation indicates significant variations of peak overpressure of shock wave of explosive with different charge masses and HOBs from radial distances, and the result can be used to analysis the propagation and attenuation of reflected shock wave of nuclear explosion.

I. Introduction

Near-surface nuclear explosions cause destructive damage and destroy to surroundings especially injuries and deaths to people, and the blast wave of nuclear explosion is one of the most serious destruction on target structure. When a nuclear bomb explodes in the air near the ground, the surrounding air is subjected to high temperature and pressure. Due to the low initial density and pressure of the surrounding air, the rarefaction wave propagates backward to the explosion products and the pressure at the point where the rarefaction wave arrives decreases rapidly, and the explosion products disperse rapidly around, forming a strong compression wave. The density, temperature, and pressure of the nearby atmosphere increase sharply. This change makes the shock wave have a strong destructive effect on the objects in the surroundings. The formation of nuclear explosion shock wave is the result of superposition of a series of compression waves. Under the condition of free propagation of shock wave, the blast shock wave intensity gradually attenuates with the distance, and finally attenuates to sound wave. When the shock wave impacts obstacles in the process of propagation, the reflection of shock wave will occur. When the incident wave is vertical to the surface of obstacles, the normal reflection of shock wave will be formed. To accurately evaluate the damage effect, the parameters of flow field after normal reflected shock wave should be investigated [1].