Ma Xiaojian, Huang Biao, Wang Guoyu, Zhang Mindi
School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing 100081, China.
School of Mechanical and Vehicular Engineering, Beijing Institute of Technology, Beijing 100081, China.
Ultrason Sonochem. 2017 Jan;34:164-172. doi: 10.1016/j.ultsonch.2016.05.027. Epub 2016 May 20.
The objective of this paper is to investigate the transient conical bubble structure (CBS) and acoustic flow structure in ultrasonic field. In the experiment, the high-speed video and particle image velocimetry (PIV) techniques are used to measure the acoustic cavitation patterns, as well as the flow velocity and vorticity fields. Results are presented for a high power ultrasound with a frequency of 18kHz, and the range of the input power is from 50W to 250W. The results of the experiment show the input power significantly affects the structures of CBS, with the increase of input power, the cavity region of CBS and the velocity of bubbles increase evidently. For the transient motion of bubbles on radiating surface, two different types could be classified, namely the formation, aggregation and coalescence of cavitation bubbles, and the aggregation, shrink, expansion and collapse of bubble cluster. Furthermore, the thickness of turbulent boundary layer near the sonotrode region is found to be much thicker, and the turbulent intensities are much higher for relatively higher input power. The vorticity distribution is prominently affected by the spatial position and input power.
本文的目的是研究超声场中的瞬态锥形泡结构（CBS）和声流结构。在实验中，采用高速视频和粒子图像测速（PIV）技术来测量声空化模式以及流速和涡度场。给出了频率为18kHz的高功率超声的结果，输入功率范围为50W至250W。实验结果表明，输入功率对CBS的结构有显著影响，随着输入功率的增加，CBS的空化区域和气泡速度明显增加。对于辐射表面上气泡的瞬态运动，可以分为两种不同类型，即空化气泡的形成、聚集和合并，以及气泡簇的聚集、收缩、膨胀和坍塌。此外，发现换能器区域附近的湍流边界层厚度要厚得多，对于相对较高的输入功率，湍流强度也高得多。涡度分布受到空间位置和输入功率的显著影响。
