University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, 1000 Ljubljana, Slovenia.
University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, 1000 Ljubljana, Slovenia.
Ultrason Sonochem. 2022 Sep;89:106159. doi: 10.1016/j.ultsonch.2022.106159. Epub 2022 Sep 6.
Acoustic cavitation, generated by a piezo-driven transducer, is a commonly used technique in a variety of processes, from homogenization, emulsification, and intensification of chemical reactions to surface cleaning and wastewater treatment. An ultrasonic horn, the most commonly used acoustic cavitation device, creates unique cavitation conditions under the horn tip that depend on various parameters such as the tip diameter, the driving frequency of the horn, its amplitude, and fluid properties. Unlike for hydrodynamic cavitation, the scaling laws for acoustic cavitation are poorly understood. Empirical relationships between cavitation dynamics, ultrasonic horn operating conditions, and fluid properties were found through systematic characterization of cavitation under the tip. Experiments were conducted in distilled water with various sodium chloride salt concentrations under different horn amplitudes, tip geometries, and ambient pressures. Cavitation characteristics were monitored by high-speed (200,000 fps) imaging, and numerous relations were found between operating conditions and cavitation dynamics. The compared results are discussed along with a proposal of a novel acoustic cavitation parameter and its relationship to the size of the cavitation cloud under the horn tip. Similar to the classical hydrodynamic cavitation number, the authors propose for the first time an acoustic cavitation parameter based on experimental results.
声空化是由压电驱动换能器产生的，它是一种广泛应用于各种过程的技术，包括均化、乳化、化学反应强化、表面清洗和废水处理等。超声变幅杆是最常用的声空化设备之一，它在变幅杆尖端产生独特的空化条件，这些条件取决于各种参数，如尖端直径、变幅杆的驱动频率、振幅和流体性质。与流体动力空化不同，声空化的缩放规律还不太清楚。通过在尖端下对空化进行系统的特性描述，发现了空化动力学、超声变幅杆工作条件和流体性质之间的经验关系。实验在不同的变幅杆振幅、尖端几何形状和环境压力下的蒸馏水中进行，并添加了不同浓度的氯化钠盐。通过高速（20 万帧/秒）成像监测空化特性，并发现了许多与工作条件和空化动力学之间的关系。本文还讨论了比较结果，并提出了一种新的声空化参数及其与变幅杆尖端下空化云尺寸的关系。与经典的流体动力空化数类似，作者首次提出了一个基于实验结果的声空化参数。
