搜索

x
中国物理学会期刊

释放疏水表面气泡: 低强度超声场中双气泡平移模式

CSTR: 32037.14.aps.75.20251537

Detachment of bubbles from hydrophobic surfaces: Dual-bubble translational modes in low-intensity ultrasound fields

CSTR: 32037.14.aps.75.20251537
PDF
HTML
导出引用
  • 微气泡在超声场中的相互作用是声流控与空化应用的核心问题. 本研究提出一种利用低强度超声, 以疏水表面作为稳定气泡源, 释放表面微气泡的实验方法, 游离出的气泡向声压波腹聚集. 通过高速摄像技术, 系统观测并分析了气泡聚集区域内耦合双气泡的相向平移行为, 识别出了4种具有显著特征的平移模式. 研究表明, 由于平移模式与气泡径向振荡的强耦合效应: 模式Ⅰ和Ⅲ表现为气泡速度弹跳与径向收缩驱动的加速碰撞, 模式Ⅱ和Ⅳ为气泡速度弹跳与径向膨胀诱导的减速碰撞. 双气泡平移碰撞数据统计分析表明, 随着功率增大, 气泡径向振荡幅度增大, 速度弹跳次数减少, 平移碰撞进程显著加快, 且在较高功率下模式Ⅲ和Ⅳ有向模式Ⅰ和Ⅱ退化的趋势. 双气泡模型的理论预测与实验得到的速度弹跳趋势一致, 揭示了双气泡径向振荡对其平移碰撞行为的调控机制. 双气泡初始半径比、初始间距以及碰撞雷诺数是调控平移模式的关键参数, 而取向角的影响并不显著. 低强度超声场中双气泡的平移运动规律, 为多气泡系统动力学建模提供了关键实验依据, 对声流控及超声空化的应用优化具有重要指导意义.

     

    The dynamic interaction of microbubbles in an ultrasonic field is a core issue for precisely manipulating acoustofluidics and the efficient application of ultrasonic cavitation. Existing microbubble generation technologies, such as ultrasonic cavitation and laser-induced nucleation, are generally limited by non-uniform bubble sizes, random spatial distribution, and the difficulty in balancing high-precision control with high-throughput repeatability. Furthermore, multi-bubble dynamics theory currently lacks systematic experimental support under multi-parameter coupling such as initial radius, spacing, and orientation angle. In this study, we propose an experimental method that uses low-intensity ultrasound, with a hydrophobic surface serving as a stable bubble source to release surface microbubbles. These microbubbles then migrate towards the acoustic pressure antinode. Using high-speed imaging technology, we systematically observe and analyze the mutual translational behaviors of coupled dual bubbles in the aggregation region, identifying four translational modes with distinct characteristics. The results indicate that the bubble aggregation region is precisely located at the acoustic pressure antinode, and the bubble area fraction within this region increases significantly as dimensionless power increases. The four identified translational modes, which are strongly coupled with radial oscillation, consist of a “velocity bouncing-collision” process. Modes I and III are characterized by accelerated collisions caused by velocity bouncing and radial contraction, whereas Modes II and IV are characterized by decelerated collisions resulting from velocity bouncing and radial expansion. Statistical analysis of the dual-bubble translational collision data demonstrates that as power increases, the amplitude of radial oscillation increases, the number of velocity bounces decreases, and the translational collision process accelerates significantly. Moreover, at higher power levels, Modes III and IV tend to degenerate towards Modes I and II. The initial radius ratio, initial spacing, and collision Reynolds number are key parameters that regulate the translational modes. Modes I and II dominate when the initial radius ratio deviates from 1 and the initial spacing exceeds 350 μm, whereas Modes III and IV are more likely to occur when the initial radius ratio approaches 1 and the initial spacing is less than 200 μm. The orientation angle has no significant effect on the modes. The predictions of the dual-bubble theoretical model show good agreement with the experimental data, which validates the precise regulatory mechanism of radial oscillation on bubble translational behavior. These insights into the translational motion laws of dual bubbles in low-intensity ultrasonic fields provide a crucial experimental basis for the dynamic modeling of multi-bubble systems, and they also hold significant implications for the optimal design of acoustofluidic devices, targeted microbubble delivery, and the optimization of ultrasonic cavitation applications.

     

    目录

    /

    返回文章
    返回
    Baidu
    map