窄缝中气泡在磁性液体中的上升与变形  

SHAPE AND VELOCITY OF AN AIR BUBBLE RISING IN A GAP FILLED WITH MAGNETIC FLUIDS

作　　者：何永清[1] 毕勤成[1] 施东晓[1] 

机构地区：[1]西安交通大学动力工程多相流国家重点实验室,陕西西安710049

出　　处：《工程热物理学报》2010年第12期2057-2060,共4页Journal of Engineering Thermophysics

基　　金：国家高技术研究发展计划(863计划)专题课题(No.2008AA05Z417)

摘　　要：对窄缝中气泡在磁性液体中的上升与变形进行了可视化研究。定性分析了纳米磁性颗粒引发的黏度效应及表面活性剂分子依附作用对气泡上升速度与形状的影响。试验工质为体积浓度6.33%的水基Fe_3O_4磁性液体,同时对比了质量浓度25%的四甲基氢氧化铵水溶液、质量分数30%和50%的蔗糖溶液以及水中气泡的上升运动。窄缝间隙分别为1 mm和2 mm,气泡由底部不同直径的圆孔产生。试验结果表明:由于活性剂分子的存在,磁性液体气泡上升过程中由扁椭圆形渐转变为上圆下平的冠状,而其略大于水的黏度使气泡在1 mm窄缝中保持直线上升运动,但窄缝间隙增大到2 mm后,磁性液体中气泡的运动轨迹仍会发生振荡。Visualization of a single bubble rising in a mini-gap filled with magnetic fluids is carried out. The effects of magnetic nanoparticles and surfactant molecules on the behavior of the bubble are investigated qualitatively. Five working fluids including water-based Fe3O4 magnetic fluids with particle volume concentration of 6.33%, water, mass concentration 25% tetramethylammonium hydroxide aqueous solution, and mass concentration 30% and 50% sucrose solution have been filled in the gaps. The widths of the gaps are 1 mm and 2 mm. The air bubble is generated through the orifice with different diameters at the bottom of the gap. Experimental results show that the shape of the bubble initially keeps ellipse like that in the water, but after the middle of the journey, it becomes as an elliptical cap like that in the surfaetant aqueous solution. Velocity of the bubble in magnetic fluids increases with the width of the gap, and the rise motion of the bubble become instable in the 2 mm gap even break up occurs.

关 键 词：磁性液体 活性剂 气泡 可视化 

分 类 号：O359[理学—流体力学]