Abstract Droplet size distribution during ultrasonic atomization was investigated by laser diffraction based on two phenomena—capillary waves and cavitation. The former was visually illustrated using the photographic method, and the latter was examined by the potassium iodide decomposition rate test and Particle Image Velocimetry technique. This study also analyzed the effects of operating ultrasonic parameters such as input power, the flow rate of liquid and gas, liquid temperature, distance from the vibrational tip to laser, and physicochemical properties of liquids (surface tension and viscosity). The relationship among capillary waves, cavitation, and the droplet size distribution was developed for the first time. Results suggest that uniform capillary waves and low cavitation intensity contribute to narrow droplet size distribution. Bimodal droplet size distribution was observed with an increasing liquid flow rate and an assisted gas flow rate. The droplet size did not keep increasing or decreasing with increasing input power and liquid viscosity. A new correlation based on all data using dimensionless numbers was then proposed to predict droplet sizes. This work presents an effective ultrasonic atomization approach to obtaining desirable droplet size distribution by choosing optimum operating parameters, and establishes the controlling mechanism for ultrasonic atomization.

中文翻译：

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超声雾化过程中毛细波、空化和液滴直径分布的研究

摘要 基于毛细波和空化两种现象，通过激光衍射研究了超声雾化过程中液滴的粒径分布。前者用照相法直观说明，后者用碘化钾分解速率试验和粒子图像测速技术检验。该研究还分析了操作超声参数的影响，例如输入功率、液体和气体的流速、液体温度、振动尖端到激光的距离以及液体的物理化学性质（表面张力和粘度）。首次开发了毛细管波、空化和液滴尺寸分布之间的关系。结果表明，均匀的毛细波和低空化强度有助于窄液滴尺寸分布。随着液体流速和辅助气体流速的增加，观察到双峰液滴尺寸分布。液滴尺寸不会随着输入功率和液体粘度的增加而不断增加或减少。然后提出了基于使用无量纲数的所有数据的新相关性来预测液滴尺寸。这项工作提出了一种有效的超声雾化方法，通过选择最佳操作参数来获得理想的液滴尺寸分布，并建立了超声雾化的控制机制。然后提出了基于使用无量纲数的所有数据的新相关性来预测液滴尺寸。这项工作提出了一种有效的超声雾化方法，通过选择最佳操作参数来获得理想的液滴尺寸分布，并建立了超声雾化的控制机制。然后提出了基于使用无量纲数的所有数据的新相关性来预测液滴尺寸。这项工作提出了一种有效的超声雾化方法，通过选择最佳操作参数来获得理想的液滴尺寸分布，并建立了超声雾化的控制机制。