Luo Jing, Fu Guihua, Xu Weilin, Zhai Yanwei, Bai Lixin, Li Jie, Qu Tong
State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China.
State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China.
Ultrason Sonochem. 2024 Dec;111:107063. doi: 10.1016/j.ultsonch.2024.107063. Epub 2024 Sep 10.
How to precisely control and efficiently utilize the physical processes such as high temperature, high pressure, and shockwaves during the collapse of cavitation bubbles is a focal concern in the field of cavitation applications. The viscosity change of the liquid will affect the bubble dynamics in turn, and further affect the precise control of intensity of cavitation field. This study used high-speed photography technology and schlieren optical path system to observe the spatiotemporal evolution of shockwaves in liquid with different viscosities. It was found that as the viscosity of the liquid increased, the wave front of the collapse shockwave of the cavitation bubble gradually thickened. Furthermore, a high-frequency pressure testing system was used to quantitatively analyze the influence of viscosity on the intensity of the shockwave. It was found that the pressure peak of the shockwave in different viscous liquid was proportional to L (L represented the distance between the center of bubble and the sensor measuring point), and the larger the viscosity was, the smaller the value of b was. Through in-depth analysis, it was found that as the viscosity of the liquid increased, the proportion of the shockwave energy of first bubble collapse to the maximal mechanical energy of bubble gradually decreased. The proportion of the mechanical energy of rebounding bubble to the maximal mechanical energy of bubble gradually increased. These new findings have an important theoretical significance for the efficient utilization of ultrasonic cavitation.
如何在空化泡溃灭过程中精确控制并高效利用高温、高压和冲击波等物理过程，是空化应用领域的一个焦点问题。液体的粘度变化会反过来影响气泡动力学，进而影响空化场强度的精确控制。本研究利用高速摄影技术和纹影光路系统，观察了不同粘度液体中冲击波的时空演化。研究发现，随着液体粘度的增加，空化泡溃灭冲击波的波前逐渐变厚。此外，使用高频压力测试系统定量分析了粘度对冲击波强度的影响。研究发现，不同粘性液体中冲击波的压力峰值与L（L表示气泡中心与传感器测量点之间的距离）成正比，粘度越大，b值越小。通过深入分析发现，随着液体粘度的增加，首次气泡溃灭的冲击波能量占气泡最大机械能的比例逐渐减小。回弹气泡的机械能占气泡最大机械能的比例逐渐增加。这些新发现对超声空化的高效利用具有重要的理论意义。
