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 引用本文: 李帅, 张阿漫, 韩蕊. 气泡多周期运动时引起的流场压力与速度[J]. 力学学报, 2014, 46(4): 533-543.
Li Shuai, Zhang Aman, Han Rui. NUMERICAL ANALYSIS ON THE VELOCITY AND PRESSURE FIELDS INDUCED BYMULTI-OSCILLATIONS OF AN UNDERWATER EXPLOSION BUBBLE[J]. Chinese Journal of Theoretical and Applied Mechanics, 2014, 46(4): 533-543.
 Citation: Li Shuai, Zhang Aman, Han Rui. NUMERICAL ANALYSIS ON THE VELOCITY AND PRESSURE FIELDS INDUCED BYMULTI-OSCILLATIONS OF AN UNDERWATER EXPLOSION BUBBLE[J]. Chinese Journal of Theoretical and Applied Mechanics, 2014, 46(4): 533-543.

## NUMERICAL ANALYSIS ON THE VELOCITY AND PRESSURE FIELDS INDUCED BYMULTI-OSCILLATIONS OF AN UNDERWATER EXPLOSION BUBBLE

• 摘要: 假设水下爆炸气泡的内部气体在膨胀收缩过程中满足绝热条件，周围流体无黏无旋不可压缩. 基于势流理论，采用边界元法研究气泡动力学行为，重点关注气泡引起的流场脉动载荷以及滞后流特性，给出了相关的理论推导和数值计算方法. 通过将数值结果与解析解、实验值进行对比，数值模型的收敛性和有效性能够得到保证. 利用编写的程序进行计算和分析，发现在气泡加速膨胀阶段，流场压力在气泡径向不一定是逐渐衰减，还有可能以先增后减的规律变化；气泡射流后，为了能够继续描述环状气泡的运动以及流场特性，将此时的流场分为无旋场和一个布置在气泡内部涡环的叠加，计算过程中采用了一些数值技巧处理气泡的拓扑结构，得以连续模拟多个周期的气泡运动. 环状气泡具有相对较高的上浮迁移速度，而且在其顶部和底部附近分别形成两个高压区，顶部的高压区峰值相对较大，底部的高压区范围相对较大. 环状气泡中心轴上的流场速度会在气泡中心有一个加速过程，在气泡顶部附近又迅速减小.

Abstract: The gas inside the underwater explosion bubble is assumed to undergo adiabatic expansion and compression. The water flow induced is assumed to be inviscid, irrotational and incompressible, which is simulated based on potential flow theory coupled with the boundary element method (BEM). Much attention was paid to the character of the pulsating pressure and the flow velocity, and the related theory and numerical method were given in detail. The validity and convergence of numerical model were confirmed by comparing the calculations with experimental and analytical results, so our BEM codes were used to simulate underwater explosion bubbles under different conditions. During the expansion phase of the bubble, the fluid pressure along the radius direction may first increase and then decrease. To simulate the subsequent motion after the bubble jet impact, a vortex ring was put inside the bubble, thus the flow field could be decomposed into two parts: an irrotational flow field and a vortex field. Besides, some numerical techniques were adopted to handle the topology of the bubble which made it possible to simulate multi-oscillations of bubbles. It's noted that there were two high-pressure regions formed around the top and the bottom of the toroidal bubble while its fast rise proceeded. It can also be found that the top region had a greater peak value, while the bottom region covered a larger area. Meanwhile, the flow velocity in the jet direction accelerated inside the toroidal bubble, but decelerated rapidly near the top of the bubble.

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