目前，关于纤维表面水滴聚结与脱落过程的研究多为定性分析，缺乏相关实验数据，并且各种因素对纤维聚结脱水效果的影响并不清晰。针对以上问题，搭建了一套可视化微流道实验系统；在航空煤油-水体系中加入表面活性剂石油磺酸盐，制备了两种不同界面张力的乳状液；利用建立的实验系统观测在不同界面张力下纤维表面水滴的聚结与脱落过程，并讨论了影响水滴聚结与脱落的主要因素。结果表明：在18 mN/m的界面张力下，最大水滴粒径在前3 min增长较快，在3 min后增长较为缓慢；在8 mN/m的界面张力下，在前6 min最大水滴粒径的增长趋势较为平缓，6 min后最大水滴粒径几乎不再增长，并且在聚结初始阶段水滴呈单侧分布；水滴单位面积的表面活性剂分子数存在饱和值，当达到饱和值时，水滴被表面活性剂分子完全包围，很难与其他水滴发生聚结行为；在18 mN/m的界面张力下，流场流速是引起水滴断裂脱落的主要原因；在8 mN/m的界面张力下，水滴的断裂脱落不仅受流场流速的影响，而且还与表面活性剂的含量有关。
Abstract
Previous studies of water droplet coalescence and shedding on fiber surfaces have mostly involved qualitative analysis. Relevant experimental data are still lacking, and the influence of various factors on the processes remains unclear. In view of the above problems, a visual microfluidic channel experimental system was built. Two emulsions with different interfacial tensions were prepared by adding petroleum sulfonate to an aviation kerosene-water system. For different interfacial tensions, the coalescence and shedding of water droplets on a glass fiber surface were observed, and the main factors affecting the coalescence and shedding of water droplets were identified. The results showed that for an interfacial tension of 18 mN/m, the maximum droplet size increases rapidly in the first 3 min, and grows slowly after 3 min. For an interfacial tension of 8 mN/m, the growth of the maximum droplet size in the first 6 min is relatively slow, and the maximum droplet size remains essentially constant after 6 min, with the water droplets unilaterally distributed in the initial stage of coalescence. The number of surfactant molecules per unit area of water droplets has a saturation value. When the saturation value is reached the water droplets are completely surrounded by surfactant molecules, which restricts coalescence with other water droplets. For an interfacial tension of 18 mN/m, the flow velocity is the main reason why water droplets break and fall off. For an interfacial tension of 8 mN/m, the breaking and shedding of water droplets is not only affected by the flow velocity of the flow field, but also depends on the amount of surfactant.
关键词
玻璃纤维 /
石油磺酸盐 /
聚结 /
水滴脱落 /
水滴断裂
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Key words
glass fiber /
petroleum sulfonate /
coalescence /
water droplet shedding /
droplets fracture
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参考文献
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