摘要现如今，科学技术日益进步，而海洋的地位也在不断攀升，水下爆炸对舰船及其 他水下结构造成损伤受到了越来越广泛的重视。本文以理论分析与数值模拟方法相结 合的方式，对水下爆炸与边界耦合作用进行研究，旨在对气泡脉动的部分特性进行分 析，以此为提高船舶的安全性、生命力和作战能力，增加水下武器的毁坏作用提供参 考。95144

首先，应用了 AUTODYN 有限元软件建立了模型，总结选取状态方程、边界条 件、计算域尺寸网格划分的方法，以及影响数值模拟精准度的程序原因，为建立水下 爆炸模型做准备。

然后，分别建立一维楔形模型和二维轴对称模型，对 0。299kg 球型 TNT 炸药在 水下 178。6m 处，以及直径为 12mm、长为 77mm 的圆柱形装药，在自由场中发生水 下爆炸时，冲击波的产生与传播过程和气泡的脉动过程进行了数值模拟。发现气泡的 脉动现象与理论比较符合，并与试验结果进行对比，验证了数值仿真方法的正确性。

最后，继续应用 AUTODYN 有限元程序建立二维轴对称计算模型。在不同的无 量纲距离参数的条件下，通过设置近自由液面、刚性边界、弹性边界三种工况，研究 了气泡的脉动过程。通过数值模拟得到了气泡形态的变化过程，进而得到了气泡的最 大半径以及脉动周期随距离参数变化的情况，并与经验公式计算值以及试验情况进行 了比较。验证了数值仿真方法的合理性。还对不同边界下的冲击波压力变化进行了模 拟。

毕业论文 关键词：水下爆炸，气泡脉动，刚性边界，弹性边界，数值模拟

ABSTRACTWith the continuous progress of science and technology, as well as the rising sea status, the damage of the ship and other underwater structure caused by underwater explosion has been more and more attention。 In this paper, the relationship between underwater explosion and boundary coupling is studied by means of theoretical analysis and numerical simulation。 The aim of this paper is to provide a reference to analyze the characteristics of bubble ripple in order to improve the safety, vitality and combat capability of the ship, and increase the destruction of underwater weapons。

Firstly, the model was established by using the AUTODYN finite element software。 The method of selecting the state equation, the boundary condition, the grid size of the domain, and the reason of the numerical simulation accuracy were summarized to prepare for the establishment of underwater explosion model。

Then, a one-dimensional wedge model and a two-dimensional axisymmetric model were established respectively。 The explosion of the shock wave and the pulsation of the bubble were carried out by Numerical simulation according to the 0。299 kg spherical TNT explosive exploded under the water at 178。6 m and the cylindrical charge with a diameter of

0。012 m and a length of 0。077 m was subjected to an underwater explosion in the free field。 It is found that the pulsation phenomenon of bubbles is in agreement with the theory。 And compared with the experimental results, the correctness of the numerical simulation method was verified。

Finally, the two-dimensional axisymmetric calculation model was established by using AUTODYN finite element program。 Under the condition of different dimensionless distance parameters, the pulsation process of bubble was studied by setting the near-free surface, rigid boundary and elastic boundary。 The maximum radius of the bubble and the change of the pulsating cycle with the distance parameter were obtained。 The rationality of the numerical simulation method were verified by comparing with the calculated formula and the experimental situation。 The variation of shock wave pressure at different boundaries was also simulated。

Key words: underwater explosion, bubble pulsation, rigid boundary, elastic boundary, numerical simulation