Bai Lixin, Wu Pengfei, Liu Huiyu, Yan Jiuchun, Su Chang, Li Chao
State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Ultrason Sonochem. 2018 Jun;44:184-195. doi: 10.1016/j.ultsonch.2018.02.030. Epub 2018 Feb 16.
Rod-shaped cavitation bubble structure in thin liquid layers in ultrasonic field is investigated experimentally. It is found that cavitation structure successively experiences several stages with the change of the thickness of the thin liquid layer. Rod-shaped structure is a stable structure of the boundary between the cavitation cloud region and the non-cavitation liquid region, which can be formed in two different ways. Cavitation bubbles in a thin liquid layer have a distribution in the thickness direction. The rod-shaped structures tend to crosslink with each other to form stable Y-branch structures. The angle of the Y-branch structure is Gauss distribution with mathematical expectation μ = 119.93. A special rod-shaped cavitation structure with source is also investigated in detail. Due to the pressure gradient in the normal direction, the primary Bjerknes force causes the bubbles in the rod-shaped structure on both sides to converge to the axis. The secondary Bjerknes forces between the bubbles also make the cluster converge, so the large bubbles which are attached to the radiating surface tend to align themselves along the central line. According to the formula deduced in this paper, the variation of curvature of curved rod-shaped structure is qualitatively analyzed. The Y-branch structure of cavitation cloud and Plateau boundary of soap bubbles are compared.
对超声场中薄液层内的棒状空化泡结构进行了实验研究。发现随着薄液层厚度的变化，空化结构依次经历几个阶段。棒状结构是空化云区域和非空化液体区域之间边界的一种稳定结构，它可以通过两种不同的方式形成。薄液层中的空化泡在厚度方向上有分布。棒状结构倾向于相互交联形成稳定的Y形分支结构。Y形分支结构的角度呈高斯分布，数学期望μ = 119.93。还详细研究了一种特殊的有源棒状空化结构。由于法向压力梯度，初级 Bjerknes 力使两侧棒状结构中的气泡向轴线汇聚。气泡之间的次级 Bjerknes 力也使气泡团汇聚，因此附着在辐射表面的大气泡倾向于沿中心线排列。根据本文推导的公式，定性分析了弯曲棒状结构曲率的变化。比较了空化云的Y形分支结构和肥皂泡的 Plateau 边界。
