不计浮力条件下边界附近气泡动态特性研究  

Boundary effects on bubble characteristics under the condition of negligible buoyancy

作　　者：王磊[1] 韩峰[1] 王爽 任云燕[1] WANG Lei;HAN Feng;WANG Shuang;REN Yunyan(State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China)

机构地区：[1]北京理工大学爆炸科学与技术国家重点实验室,北京100081

出　　处：《兵器装备工程学报》2022年第3期223-228,共6页Journal of Ordnance Equipment Engineering

摘　　要：边界面附近水下爆炸爆轰产物形成的气泡呈非球状脉动,尤其是坍塌阶段气泡表面各处径向收缩速度不均匀的现象更为显著,气泡偏离球形严重,甚至形成水射流。基于LS-DYNA的S-ALE方法,分别建立自由面及刚性壁面附近水下爆炸流场的有限元模型,结合典型时刻气泡外部流场压力云图演化,分析不计浮力条件下边界附近气泡动态特性及相关物理现象背后的力学机理,结果表明:在自由面附近,气泡体积达到最大时顶部曲率最高,坍塌阶段气泡顶部附近流场中形成局部高压区,局部高压区导致气泡顶部收缩加快,并形成背离自由面方向的水射流;水平刚性壁面附近气泡下端与壁面间的连通低压区和收缩阶段气泡顶部附近流场中形成的局部高压区是导致气泡中心趋近壁面的原因,该局部高压区致使坍塌中后期气泡顶部产生朝向壁面方向的水射流;自由面边界对高压气泡具有吸引作用,对低压气泡具有排斥作用。刚性壁面边界的作用与之相反。Non-spherical pulsation of an underwater explosion bubble occurs under the boundary conditions.Especially during the collapse phase,radial velocities throughout the bubble surface vary dramatically,which may lead to the formation of a high-speed liquid jet.The S-ALE method of LS-DYNA was applied to simulate bubbles interaction with free surface and a rigid wall respectively.Under the condition of negligible buoyancy,the mechanism behind bubble dynamic characteristics near boundaries was analyzed through the pressure nephogram.The presence of a nearby boundaries lead to desynchrony of expansion and collapse around the bubble surface.Under the influence of free-surface,curvature of the bubble roof is the largest at the beginning of the collapse phase.Gradually,a local high-pressure region is generated near the bubble roof.The local high-pressure region increases the collapse speed of the bubble roof,which results in the formation of jet away from free-surface.For the situation nearby a rigid wall,a local low-pressure region near the bubble bottom and a local high-pressure region near the bubble roof cause the bubble center to approach the rigid wall.The local high-pressure region increases the collapse speed of the bubble roof,which leads to the formation of jet towards the rigid wall.The free surface boundary has an attractive effect on high-pressure bubbles and a repulsive effect on low-pressure bubbles.The rigid wall boundary has the opposite effect.

关 键 词：水下爆炸 边界效应 气泡脉动 气泡迁移 水射流 

分 类 号：O358[理学—流体力学]