不同浓度离子溶液中气泡运动特性的实验研究

Experimental Study on Bubble Motion Characteristics in Ionic Solutions with Different Concentrations

气泡运动特性可以分析流型形成和演化,是探究两相流模型构建的基础。为了进一步研究气泡在多种溶液内的运动特性,搭建了气泡运动特性实验平台。在3种浓度的FeCl_(3)、CaCl_(2)、NH_(4)Cl离子溶液及去离子水内,对单个气泡运动特性进行了实验研究,利用高速相机拍摄图片并导入MATLAB软件进行了计算。据此,分析了离子溶液内单个气泡的上升时间,脱离时间,初始当量直径,以及纵横比。结果表明:离子溶液,尤其是CaCl_(2)溶液在一定程度上可以促进气泡在喷嘴处的脱离,使得脱离时间减少,当喷嘴为1.5 mm时,促进作用最为明显;三种离子溶液和去离子水比较,气泡上升时间都有所缩短,但是相差不大;三种离子溶液中,FeCl_(3)溶液中气泡纵横比变化最大;NH_(4)Cl溶液对气泡的当量直径促进作用最强,CaCl_(2)溶液会抑制气泡当量直径的发展,因此在特殊流体机械内部,应适当增加钙离子以降低冲击带来的腐蚀与振动;在去离子水和三种离子溶液中气泡的纵横比δ都会有一个“L”型分布,且最大值均出现在气泡脱离喷嘴的瞬间。

The motion of bubbles can be used to analyze the formation and evolution of flow patterns,which is the basis for exploring the construction of two-phase flow models.In order to further study the motion characteristics of air bubbles in various solutions,we built an experimental platform for bubbles.We experimentally studied the motion characteristics of a single-air bubble in three concentrations of FeCl_(3),CaCl_(2),NH 4Cl ionic solution and deionized water.In the experiment,we used a high-speed camera to take pictures and put them into MATLAB software for calculation.Based on the data,we analyzed the rise time,detachment time,initial equivalent diameter,and aspect ratio of single bubbles in the ionic solution.The results show that the ionic solution can promote the detachment of bubbles at the nozzle to a certain extent,which reduces the detachment time.Especially when the nozzle is 1.5 mm,the promotion effect is most obvious.Compared with deionized water,the rise time of all three bubbles is shortened,but the difference is small.Among the three ionic solutions,the bubble aspect ratio changes the most in FeCl_(3) solution.The NH_(4)Cl solution has the strongest promotion effect on the initial equivalent diameter of bubbles,while the CaCl_(2) solution can inhibit the development of the equivalent diameter of bubbles.Therefore,in the special fluid machinery,calcium ions should be appropriately increased to reduce the impact of corrosion and vibration.The aspect ratio of the air bubbles in both deionized water and the three ion solutions will have an L-shaped distribution,and the maximum aspect ratio occurs at the moment when the bubbles leave the nozzle.