高速破片穿透液舱的数值模拟研究

Numerical simulation of a high-speed fragment penetrating a liquid tank

在水下近场爆炸载荷的研究中,高速破片侵彻问题异常复杂,由于爆炸实验的不可重复性和危险性,如何运用数值仿真较好地模拟侵彻问题一直备受关注。运用耦合的欧拉-拉格朗日(CEL)算法,开展了高速破片侵彻液舱实验模型的仿真,验证了CEL算法在处理侵彻问题的可靠性和准确性;在此基础上,开展了不同破片速度和液体装载量对穿透压力和空穴演化的影响研究。结果表明:破片速度衰减规律、空穴演化以及侵彻过程中压力时历曲线与实验值基本一致;弹道远离液面时,液体装载量并不影响速度衰减规律;随着与自由液面距离减小,近自由液面入射弹道非对称性差异可由20%增加到48%;破片初始速度增加,前置隔板的变形略有增加,后置隔板的变形呈非线性增长。

The penetration of high speed fragments has been concerned for a long time which always occurs during the process of near-field underwater explosions. Due to the randomness of explosions and expensive costs of the explosion tests, it’s important to build a numerical model to simulate it exactly. In the present paper, the coupled eulerian-lagrangian(CEL) method was applied to simulate the process of a high speed fragment impacting on a liquid tank. Furthermore, the effects of the fragment velocity and liquid quantity on the pressure and cavity evolution were discussed. The numerical results, including the velocity decay vs. time of fragment, cavity evolution and pressure at different points of the fluid under different impact velocities, are quite consistent with the experimental tests results. If the trajectory is far away from the surface, the velocity decay vs. time is not influenced by the liquid quantity. As the distance from the free liquid surface decreases, the asymmetrical difference of incident trajectory will increase from 20% to 48%. The deformation on the entry wall of a tube is in direct proportion to the initial velocity of fragments, while the deformation on the exit wall has a nonlinear increase.