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中文核心期刊

近场水下爆炸瞬态强非线性流固耦合无网格数值模拟研究

NUMERICAL SIMULATION OF TRANSIENT STRONGLY-NONLINEAR FLUID-STRUCTURE INTERACTION IN NEAR-FIELD UNDERWATER EXPLOSION BASED ON MESHLESS METHOD

  • 摘要: 近场水下爆炸涉及多相流体的掺杂耦合以及结构的大变形、损伤和断裂等瞬态强非线性现象, 传统的网格算法在模拟近场水下爆炸时面临结构网格畸变、多相界面捕捉精度不足等难题, 鉴于此, 本文建立了完全无网格的近场水下爆炸冲击波和气泡全物理过程瞬态强非线性流固耦合动力学模型. 流体采用基于黎曼求解器的光滑粒子流体动力学(SPH)方法求解, 结构采用重构核粒子法(RKPM)求解, 并基于法向通量边界条件实现流固耦合. 为提高SPH对流场间断的求解精度, 引入黎曼问题思想并结合MUSCL重构算法, 为解决流场粒子体积变化剧烈导致的精度下降问题, 应用了自适应粒子分割与合并方法. 为模拟水下爆炸对结构造成的损伤断裂, 基于退化实体几何表述, 采用Lemaitre损伤算法, 建立了RKPM壳结构断裂损伤模型. 依据所建立的SPH-RKPM流固耦合模型, 对近场水下爆炸冲击波传播、气泡脉动与射流以及结构毁伤进行了模拟, 将得到的冲击波载荷、气泡演化以及结构响应与实验值和其他数值解对比, 验证了当前建立的SPH-RKPM流固耦合模型的有效性和精度, 并给出了水下爆炸载荷特性及其对结构的流固耦合毁伤机制与规律, 旨在为近场水下爆炸载荷预报提供理论和基础性技术支撑, 为毁伤威力评估和舰船防护结构设计提供参考.

     

    Abstract: Near-field underwater explosion involves transient and strongly nonlinear phenomena such as the mixing and coupling of multi-fluid flows, and the large deformation, damage and fracture of the structure. For the simulation of near-field underwater explosion, traditional mesh-based methods often face some difficulties, such as structural mesh distortion, low-accuracy in capturing multiphase interface and so on. In this regard, based on completely meshless methods, a transient strongly-nonlinear fluid-structure interaction numerical model is established for the whole Physical process of near-field underwater explosion including shock wave and bubble. The smooth particle hydrodynamics (SPH) based on Riemann solver is used for solving fluid dynamics, and the reproducing kernel particle method (RKPM) is adopted for structural dynamics. The fluid-structure interaction is realized by using the normal flux boundary condition. In order to improve the accuracy in solving the discontinuities of the flow field, the Riemann problem concept is introduced and combined with the MUSCL reconstruction algorithm. Aiming to solve the problem of accuracy decline caused by the drastic change of particle volume in the flow field, the adaptive particle splitting and merging algorithms are applied. To simulate the damage and fracture caused by underwater explosion, based on Lemaitre damage algorithm, the damage and fracture models for RKPM shell structure is proposed, and the crack initiation algorithm is developed according to the visual criterion. Based on the established SPH-RKPM model, the shock wave propagation, the bubble pulsation and jet, and structural damage in the near-field underwater explosion are simulated. The obtained fluid load and structural response are compared with the experimental data and other numerical solutions to verify the effectiveness and accuracy of the SPH-RKPM fluid-structure interaction model, and the underwater explosion load characteristics as well as the mechanism and law of the fluid-structure interaction structure damage are given. The present work aims to provide technical support for the load prediction of near-field underwater explosion, and to provide reference for the damage power assessment and warship protective structure design.

     

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