声流条件下超声空化气泡分布研究

研究了频率为20 kHz的超声作用在圆柱形料腔中出现声流现象时超声空化效应的空间分布特性。结合大振幅声源条件下的声辐射力，对声场内的声流现象进行了仿真分析，获取了不同超声功率和液位高度下的声流速度场分布，初步探究了声流条件下空化气泡的运动分布规律。采用超声空化效应的声致化学发光实验，对比研究了有、无声流条件时超声空化效应的空间分布特性。结果表明：功放电流高于80 mA(电功率为17.6 W)时，超声场可形成稳定的声致流动现象且可有效提高其声能辐射效率，大大增加了空化效应的作用区域，进而提高了声化学反应效率；声流条件下料腔内超声空化效应的分布区域与超声功率(振幅)、料腔液位高度相关，功放电流从40 mA(电功率为8.8 W)增加至120 mA(电功率为26.4 W)时，空化面积占比提高了100.86%，液位高度为60 mm时的空化面积占比较50 mm和70 mm时分别提高了13.11%和73.91%，提高超声功率及选择合理的料腔液位高度，可有效提高空化气泡扩散距离，增大空化分布面积；对于固定形状及尺寸料腔中的声场，声流速度达到一定阈值时，会出现空化效应增强，空化效应增强区域位于大于声流速...

Research on ultrasonic cavitation bubble distribution under the condition of acoustic flow

The spatial distribution characteristics of the ultrasonic cavitation effect are studied when applying 20 kHz ultrasound on the sound field of a cylindrical reactor to form acoustic flow phenomenon. Combined with the acoustic radiation force from large amplitude sound source, the acoustic flow phenomenon of sound field is studied through simulation analysis. The velocity field distributions of acoustic flow under different ultrasonic powers and liquid level heights are obtained, and the motion distribution law of cavitation bubble under the condition of acoustic flow is preliminarily explored. The sonochemiluminescence experiment of ultrasonic cavitation effect is conducted to study the spatial distribution characteristics of ultrasonic cavitation effect under the condition with and without acoustic flow. The results are shown as follows: when the power amplifier current is higher than 80 mA (the electric power is 17.6 W), stable acoustic flow phenomenon forms in the ultrasonic field, which can effectively improve the acoustic energy radiation efficiency, greatly increase the cavitation effect area, and thereby improve the sonochemical reaction efficiency. The distribution area of ultrasonic cavitation effect in the reactor is related to the ultrasonic power (amplitude) and the height of the liquid level: when the current of power amplifier is increased from 40 mA (electric power 8.8 W) to 120 mA (electric power 26.4 W), the proportion of cavitation area increases by 100.86%, and for the liquid level is 60 mm, the cavitation area proportion increases by 13.11% and 73.91% respectively compared with these for the liquid levels of 50 mm and 70 mm; the diffusion distance of cavitation bubbles can be effectively increased and the cavitation distribution area can be increased by increasing the ultrasonic power and selecting the reasonable liquid level; for the reactor with fixed shape and size, when the acoustic flow velocity reaches a certain threshold, the cavitation effect will be enhanced, and the area of cavitation effect enhancement is located in the region where the acoustic flow velocity is greater than the threshold; the main diffusion distribution of cavitating bubbles is closely related to the acoustic flow velocity field; there are three kinds of diffusion patterns: radial diffusion in the middle of the reactor, diffusion along the axial direction of the horn and radial diffusion at the bottom of the reactor, as well as diffusion along the axial direction of the horn.