摘要
研究了不同粒径单液滴在去离子水中和加入表面活性剂的去离子水中的形变、上升速度和曳力系数等动力学参数,液滴当量直径范围2.90 mm<D_e<11.11 mm,液滴雷诺数范围120<Re<800。考虑到表面活性剂的加入对不同大小液滴形变的影响,通过与无因次参数的拟合,将不同体系中液滴的形变比、终速度和曳力系数同文献中不同体系参数下气泡和液滴的实验结果进行对比,结果表明:液滴的形变比随厄缶数(Eo)的增大而减小,表面活性剂的加入增大了液滴的形变程度,打破了液滴的对称性;Tomiyam对终速度的拟合考虑到液滴的形变,更符合本实验液滴运动终速度的平均值;液滴曳力系数先随雷诺数的增大而减小,在Re=360时出现极值点,随后曳力系数随雷诺数的增大而增大,此现象与液滴的形变和横向振荡有关。针对液滴的横向振荡行为,运用傅立叶变化研究了表面活性剂的加入对液滴横向振荡特征频率的影响。
The shape,rise velocity and drag coefficient of a single drop,with diameters varying from 2. 90 mm to11. 11 mm,rising in distilled water and in water contaminated with surfactants are discussed,where the drops have Reynolds numbers from 120 to 800. The primary role of the surfactant in the deformation of a drop and its effect on the terminal velocity and drag coefficient are considered. Results for aspect ratio,terminal velocity and drag coefficient are compared with the previous correlations of both bubble and drop motions in pure and contaminated systems. The results show that drops deformed markedly in the contaminated system and the deformation ratio decreased with the increase of Etvs number（ Eo）. A semi-empirical approach developed by Tomiyam,which considers the deformation ratios,gives a good prediction of the average terminal velocity of the drops. The minimum value of the drag coefficient was found at Re = 360 which can be associated with the transverse oscillation of drops.The effect of the surfactants on the oscillation of the drops was investigated by using Fourier analysis.
出处
《北京化工大学学报（自然科学版）》
CAS
CSCD
北大核心
2016年第4期33-39,共7页
Journal of Beijing University of Chemical Technology(Natural Science Edition)
基金
国家自然科学基金(21206002/21376016)
关键词
单液滴
表面活性剂
形变
终速度
single drop
surfactants
deformation
terminal velocity
