Wang Zhaohui, Ding Weibing, Fan Yiwei, Wang Jian, Chen Jie, Wang Hongxia
Key Laboratory of Metallurgical Equipment and Control Technology of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China.
The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China.
Micromachines (Basel). 2022 Oct 19;13(10):1776. doi: 10.3390/mi13101776.
This paper proposed an improved flow-focusing microchannel with a constricted continuous phase inlet to increase microbubble generation frequency and reduce microbubbles' diameter. The design variables were obtained by Latin hypercube sampling, and the radial basis function (RBF) surrogate model was used to establish the relationship between the objective function (microbubble diameter and generation frequency) and the design variables. Moreover, the optimized design of the nondominated sorting genetic algorithm II (NSGA-II) algorithm was carried out. Finally, the optimization results were verified by numerical simulations and compared with those of traditional microchannels. The results showed that dripping and squeezing regimes existed in the two microchannels. The constricted continuous phase inlet enhanced the flow-focusing effect of the improved microchannel. The diameter of microbubbles obtained from the improved microchannel was reduced from 2.8141 to 1.6949 μm, and the generation frequency was increased from 64.077 to 175.438 kHz at the same capillary numbers (Ca) compared with the traditional microchannel. According to the fitted linear function, it is known that the slope of decreasing microbubble diameter with increasing Ca number and the slope of increasing generation frequency with increasing Ca number are greater in the improved microchannel compared with those in the traditional microchannel.
本文提出了一种改进的流动聚焦微通道，其连续相入口处有收缩结构，以提高微气泡产生频率并减小微气泡直径。通过拉丁超立方抽样获得设计变量，并使用径向基函数（RBF）代理模型建立目标函数（微气泡直径和产生频率）与设计变量之间的关系。此外，还对非支配排序遗传算法II（NSGA-II）算法进行了优化设计。最后，通过数值模拟验证了优化结果，并与传统微通道的结果进行了比较。结果表明，两种微通道中均存在滴状和挤压状流型。收缩的连续相入口增强了改进型微通道的流动聚焦效果。与传统微通道相比，在相同毛细管数（Ca）下，改进型微通道产生的微气泡直径从2.8141μm减小到1.6949μm，产生频率从64.077kHz增加到175.438kHz。根据拟合的线性函数可知，与传统微通道相比，改进型微通道中微气泡直径随Ca数增加而减小的斜率以及产生频率随Ca数增加而增加的斜率更大。
