液体薄层中环链状空化泡云结构稳定性分析  

Structure stability of cyclic chain-like cavitation cloud in thin liquid layer

作　　者：李凡 张先梅 田华[1] 胡静[1] 陈时[1] 王成会[1] 郭建中[1] 莫润阳[1] Li Fan;Zhang Xian-Mei;Tian Hua;Hu Jing;Chen Shi;Wang Cheng-Hui;Guo Jian-Zhong;Mo Run-Yang(Institute of Shaanxi Key Laboratory of Ultrasonics,Shaanxi Normal University,Xi’an 710062,China)

机构地区：[1]陕西师范大学,陕西省超声学重点实验室,西安710062

出　　处：《物理学报》2022年第8期176-183,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11974232,11727813)资助的课题~~。

摘　　要：为分析超声空化的薄层液体中稳定的环状气泡链结构,本文考虑气泡间次级声辐射影响,得到了表征气泡间相互作用的气泡基本动力学方程以及次Bjerknes力的表达式,数值分析了气泡平衡半径、声波频率和声压对纯液体区可能出现的单气泡所受的次Bjerknes力,发现环形泡链能够吸引液体区内的新生的半径小于2μm的气泡,这可能是一定条件下环形气泡链能够稳定存在的原因.随着驱动声波压力增加,气泡数密度增加,气泡间的耦合作用增强,液体区内的环形泡链结构可能被液体区内出现的大气泡或者气泡团破坏,进而导致环形结构演变成柱状、雾状乃至整个液体区均充满空化泡的情况发生.通过高速摄影机观察了强声场作用下换能器辐射面外侧液体薄层内空化初生至形成空化云团簇的整个过程,在空化云团簇中发现了局部同步崩溃并形成类纯液体薄层的现象,该液体薄层边界随时间振荡持续约4个声周期后被空化云团簇吞没,局部类纯液体区出现的位置具有随机性.实验观察结果和理论预测具有很好的一致性.In this paper,the evolution of the cavitation bubbles is investigated.A model is developed to describe the cyclic chain-like cavitation cloud and analyze its structure stability in a thin liquid layer.By considering the effect of secondary acoustic radiation of bubbles,the dynamic equations of the bubbles in three zones of the cyclic chain are obtained.The secondary Bjerknes force is selected and used to explore the interaction between the bubbles in different regions.Numerical results show that the newborn bubbles inside the pure liquid zone of the thin layer can be attracted by the bubbles at the cyclic chain-like bubble chain.The bubble number density can affect the coupling strength between bubbles,and it is closely related to the driving pressure.Therefore,the structure stability of cyclic chain-like cavitation cloud can be disrupted by the perturbations of the acoustic pressure.To verify our analysis,we observe the structure of cavitation cloud in a thin liquid layer in a strong acoustic field by using a high speed camera.It is observed that the simultaneous collapse of local bubbles occurs,and pure liquid-like thin layers are distributed in the bubble cloud randomly.The boundary of the pure liquid-like thin layers oscillates with the acoustic field,and these liquid zones sustain about 4 acoustic cycles.The experimental results accord well with theoretical results.

关 键 词：超声空化结构 气泡群 次Bjerknes力 稳定性 

分 类 号：O35[理学—流体力学]