超声辐照及辐照环境对液体中流场分布特性的影响

研究了超声辐照下液体中声压场分布,模拟了流场分布的特性,模拟结果与利用粒子成像测速仪得到的实验结果相符。进一步研究了声学参数及容器几何环境对流场分布的影响。研究发现,增大超声功率和频率可使流场速度变大:在30~60W范围内,超声功率与流场中最大流速间存在线性关系;在频率为100~472kHz范围内,流场速度大小随频率的升高而增加:在层流区,流速与频率的平方成正比;在湍流区,流速与频率的1/2次方成正比。进一步研究发现,随着换能器到容器壁间距离的增加,流场速度减小。 

Influence of ultrasonic irradiation on distribution of the flow field

Distribution for ultrasonic pressure field in a vessel was simulated, and the results are in good agreement with experimental results. On this basis, the flow field was simulated by the use of the distribution of the ultrasound field. Results were compared with experimental results obtained by particle image velocimetry. The influence of acoustical and geometric parameters for the flow field was discussed. Results have indicated that ultrasonic power enhances the flow field, and the maximum of the liquid velocity is linear to the ultrasonic power in a range. Within ultrasonic frequency range from 100 kHz to 472 kHz, the flow field was enhanced by the increase of frequency. The liquid velocity is proportional to the square of the frequency when flow is laminar flow. The liquid velocity is proportional to the square root of the frequency. The influence of the vessel size on the flow field was also discussed: with increasing distance from the transducer to the walls of the vessel, the flow field velocity decreases.