水下爆炸冲击凹陷液面诱导射流研究  

A study on jet flow induced by underwater explosion at a pit-interface

作　　者：张桂夫[1] 朱雨建[1] 杨基明[1] 

机构地区：[1]中国科学技术大学近代力学系,安徽合肥230026

出　　处：《爆炸与冲击》2018年第2期241-249,共9页Explosion and Shock Waves

基　　金：国家自然科学基金项目(11572313;11621202)

摘　　要：利用液滴坠落冲击直管中水平液面产生半球形凹陷,并以此凹陷液面作为初始界面进行水下爆炸冲击诱导射流的实验研究。以高速摄影为主要手段,结合Fluent数值模拟,揭示了凹陷液面在水下爆炸冲击作用下的变形过程和机理。实验结果表明,随着爆炸的发生,液面凹陷中心会汇聚形成纤细光滑的射流,同时在管壁附近会产生附加环状射流,这明显区别于冲击直管中水平液面诱导射流的现象。进一步研究发现,中心射流的产生主要源于液面凹陷对爆炸能量的汇聚作用,而附加射流的产生受到液面初始形状和管壁剪切阻力的共同影响,二者经历短暂的加速过程之后均以一个近似恒定的速度向上抬升。通过考察能量对射流的影响发现,中心射流与附加射流的速度均与充电电压(爆炸能量的1/2次方)呈线性正相关;中心射流形态特征基本不变,附加射流则随能量的变化呈现不同的形态。In this study we conducted an experiment on the jetting flow induced by underwater wire explosion at an interface with a quasi-static hemispherical pit,in which the interfacial pit was created by the dripping of a liquid drop.Further,using high-speed video photography and Fluent numerical simulation,we revealed the development and features of the jetting flow,tested and verified the applicability of the pit creation method.The experimental results show that the explosion induces a slim and smooth central jet that arises from the bottom of a pit,and a circular side jet arises from the boundary region of the tube,which differs from the known jetting phenomenon without a pit at the surface.Further study reveals the central jet is a result of the energy concentration effect of the pit under impact and the circular side jet is caused by a combined effect of the disturbed initial interface and the friction of the tube wall.Both jets rise with an early constant velocity after a short acceleration process.Examination of the explosion energy indicates that the velocities of the two jets increase linearly with the charging voltage(or equivalently the square root of the explosion energy).The explosion energy barely affects the general feature of the central jet but has a significant influence on the appearance of the side jet.

关 键 词：射流 水下爆炸 直管 液滴坠落 凹陷液面 

分 类 号：O381[理学—流体力学] O358[理学—力学]