Effect of microscopic interfacial structure on gas-liquid two phase flow and application for flow control.

微观界面结构对气液两相流动的影响及其在流量控制中的应用。

• 批准号: 08455088
• 负责人: MATSUMOTO Yoichiro
• 金额: $ 5.63万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455088/
• 关键词: Surfactant; Rising Bubble; Marangoni Effect; Terminal Velocity; Experiment; Ultra Pure Water; Numerical Simulation; Adsorption

Transport phenomena of mass, momentum and energy at gas liquid interface is most important basis for gas-liquid two phase flow and various drastically with interface condition. For example, it is known that additon of surfactant gives large influence on whole flow structure of bubbly flow which includes numbers of bubbles in liquid by preventing coalition and reducing rising velocity of bubbles. The purpose of this research is to clarify relation between bulk concentration of surfactant existing liquid and interfacial structure, and quantitative analysis of influence of impurity on macroscopic flow dynamics of two phase flow. Experiment of rising bubble in stationaly liquid by using ultra pure water and surfactant solution of known concentration, and simulation of rising bubble by using Navier-Stokes equation coupled with Marangoni effect were conducted to investigate mechanism of basic interfacial phenomena.In the experiment, behavior of the rising bubble was investigated by generatin … More g small single bubble of 50mum to 1mm in radius in stationary water. Relation between Reynolds number and drag coefficient for rising bubble in the ultra pure water was confirmed to be same as one derived from theory for pure liquid. Moreover, it was observed that addition of small amount of 3-pentanol into pure water reduces rising velocity significantly.In the numerical simulation, effect of surfactant on drag of rising bubble was analyzed for undeformable spherical bubble by adopting absorption model of Henry type or Langmuir type and by using orthogonal curvilinear coordinate system along bubble interface. As a result of numerical simulation, it was demonstrated that drag of the rising bubble can remarkably increase by Marangoni effect for even small amount of surfactant, and that the Marangoni effect becomes important with Reynolds number for bubbles having same diameter and same terminal velocity. Further, the simulation shows separating vortices associated with secondary vortices behind the bubble rising in surfactant solution, never observed in pure water. Less

气液界面上的质量、动量和能量输运现象是气液两相流动的重要基础，并且与界面条件有很大的不同。例如，表面活性剂的加入通过阻止聚集和降低气泡的上升速度，对气泡流的整体流动结构(包括液体中气泡的数量)有很大的影响。本研究的目的是阐明表面活性剂存在液体的体积浓度与界面结构之间的关系，并定量分析杂质对两相流宏观流动动力学的影响。用已知浓度的超纯水和表面活性剂溶液对静止液体中气泡的上升进行了实验研究，并用考虑了Marangoni效应的纳维斯托克斯方程对上升气泡进行了模拟，探讨了基本界面现象的机理。实验中，用…研究了上升气泡的行为静止水中半径50微米至1毫米的单个小气泡较多。超纯水中上升气泡的雷诺数与阻力系数的关系与纯液体的理论关系一致。此外，还观察到在纯水中加入少量的3-戊醇显著降低了上升速度。在数值模拟中，采用Henry或Langmuir类型的吸收模型，采用沿气泡界面的正交曲线坐标系，分析了表面活性剂对不可变形球形气泡上升阻力的影响。数值模拟结果表明，即使加入少量表面活性剂，Marangoni效应也能显著增加上升气泡的阻力；对于相同直径和相同终速的气泡，随着雷诺数的增加，Marangoni效应变得更加重要。此外，模拟还显示了在表面活性剂溶液中从未观察到的与气泡上升后的二次涡相关的分离涡。较少

项目成果

A.Yamamoto, M.Hirase, O.Nakabeppu, S.Takagi and Y.Matsumoto: "The Effects of Impurity on a Rising Bubble" Proceedings of 11th Symposium on Numerical Fluid Dynamics. 229-230 (1997)

A.Yamamoto、M.Hirase、O.Nakabeppu、S.Takagi 和 Y.Matsumoto：“杂质对上升气泡的影响”第 11 届数值流体动力学研讨会论文集。

山本, 平瀬, 中別府, 高木, 松本: "液中の上昇気泡に対する不純物の影響" 第11回数値流体力学シンポジウム講演論文集. 229-230 (1997)

Yamamoto、Hirase、Nakabeppu、Takagi、Matsumoto：“杂质对液体中上升气泡的影响”第 11 届计算流体动力学研讨会论文集 229-230（1997 年）。