• 研究论文 •

### 超声波作用下气泡的非线性振动

1. 陕西师范大学应用声学研究所
• 收稿日期:2009-09-03 修回日期:2010-04-16 出版日期:2010-12-10 发布日期:2010-12-02
• 通讯作者: 王成会 E-mail:wangld001@snnu.edu.cn

### The nonlinear oscillation of bubbles in the ultrasonic field

Chenghui Wang 王成会,

1. Applied Acoustics Institute, Shaanxi Normal University, Xi'an 710062, China
• Received:2009-09-03 Revised:2010-04-16 Online:2010-12-10 Published:2010-12-02
• Contact: Chenghui Wang 王成会 E-mail:wangld001@snnu.edu.cn

Abstract: The nonlinear oscillation can be described by Flynn Equation when considering the compressibility of inner gas of bubbles. Based on the model the displacement/the time relation and phase-trajectory of vibrating bubbles of different initial radii are simulated numerically, which shows that the movements of bubbles depend strongly on the initial conditions in the same sound field. When the driving frequency of 26.5kHz and intensity of 1.35atm is adopted, the bubbles oscillate forcedly with initial radii are smaller than 1\mu m, while oscillate quasi-intrinsically with initial radii larger than 200\mu m. The two kinds of bubbles are not cavitation ones. The changes of smaller bubbles are more intense to the sound intensity. If the sound intensity increases, a restricted range of bubbles smaller than 1\mu m can become cavitation ones. Furthermore, the smaller the initial radius is, the larger the increase of maximum displacement is. In addition, the driving frequency also affects the movement of bubbles. With the increase of driving frequency, the initial radii range of cavitation bubbles decrease, and the oscillation intensity reduces. The results present that there are three types of bubbles in the ultrasonic field: big bubbles oscillated quasi-intrinsically, cavitation bubbles and micro-bubbles oscillated forcedly at the driving frequency. The size range of cavitation bubbles is influenced jointly by driving frequency and pressure amplitude. At the same time, we researched the bubbles field in tap water by high speed photography when the ultrasonic transducer is working. The results show that there is a mixed field, where many bubbles with different radius are vibrating and moving. Not only cavitation bubbles but also bubbles with the millimeter scales coexist in the radiation field of ultrasonic transducer. The movements of bubbles can affect the intensity of cavitation directly. There is a complex physical field when cavitation comes into being in the liquid, where bubbles are vibrating, colliding and combining.

Key words: high speed photography

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