College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, PR China.
College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, PR China.
Ultrason Sonochem. 2018 Mar;41:319-326. doi: 10.1016/j.ultsonch.2017.09.055. Epub 2017 Sep 30.
Droplets banding is critical to emulsion separation under ultrasonic irradiation as it can greatly improve the separation efficiency. In this paper, the formation process of droplets banding under ultrasonic standing waves was precisely captured by high-speed microscopic photography; by processing the images, the droplets banding characteristics, including the banding formation time and banding interval, were extracted. Then the effects of acoustic intensity, frequency, droplet size, and physical properties of oil and water on the droplets banding characteristics were discussed in details. The results show that the range of acoustic intensities, within which the droplets banding can form, increases with the increase of the frequency; a maximum allowable acoustic intensity exists for banding formation, which also increases with the frequency. The banding formation time, which increases with increasing oil viscosity but decreases with droplet size, is found to be hardly affected by the oil-water interfacial tension. In addition, the banding interval is only related to the frequency, which closely corresponds to the half wavelength.
液滴成带对于超声辐照下乳液的分离至关重要，因为它可以大大提高分离效率。本文通过高速显微摄影精确捕捉了超声驻波下液滴成带的形成过程；通过图像处理，提取了液滴成带的特征，包括成带形成时间和带间距。然后详细讨论了声强、频率、液滴大小以及油和水的物理性质对液滴成带特征的影响。结果表明，在一定频率范围内，可形成液滴成带的声强范围随着频率的增加而增大；存在一个最大允许声强用于成带形成，该声强也随着频率的增加而增大。成带形成时间随油粘度的增加而增加，随液滴尺寸的增加而减小，但受油水界面张力的影响很小。此外，带间距仅与频率有关，且与半波长密切相关。
