Surface tension and quasi-emulsion of cavitation bubble cloud.
A quasi-emulsion phenomenon of cavitation structure in a thin liquid layer (the thin liquid layer is trapped between a radiating surface and a hard reflector) is investigated experimentally with high-speed photography. The transformation from cloud-in-water (c/w) emulsion to water-in-cloud (w/c) emulsion is related to the increase of cavitation bubble cloud. The acoustic field in the thin liquid layer is analyzed. It is found that the liquid region has higher acoustic pressure than the cloud region. The bubbles are pushed from liquid region to cloud region by the primary Bjerknes forces. The rate of change of CSF increased with the increase of CSF. The cavitation bubbles on the surface of cavitation cloud are attracted by the cavitation bubbles inside the cloud due to secondary Bjerknes forces. The existence of surface tension on the interface of liquid region and cloud region is proved. The formation mechanism of disc-shaped liquid region and cloud region are analysed by surface tension and incompressibility of cavitation bubble cloud.
Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China. Electronic address: blx@mail.ioa.ac.cn.
Lixin
L
Bai
State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, China.
Xiaoguang
X
Chen
Beijing Aerospace Institute for Metrology and Measurement Technology, Beijing 100076, China.
Gang
G
Zhu
State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China.
Weilin
W
Xu
Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
Weijun
W
Lin
Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
Pengfei
P
Wu
Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
Chao
C
Li
Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
Delong
D
Xu
State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, China. Electronic address: jcyan@hit.edu.cn.
Jiuchun
J
Yan
Cavitation bubble cloud; Cavitation structure; Quasi-emulsion; Surface tension; Ultrasonic cavitation