2022 Fiscal Year Final Research Report
Relationship between micelle structure and near-wall turbulence in surfactant drag-reduced flow
| Project/Area Number |
20K04271
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 19010:Fluid engineering-related
|
|---|
| Research Institution | Osaka Metropolitan University (2022)
Osaka City University (2020-2021) |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2020-04-01 – 2023-03-31
|
| Keywords | 抵抗低減 / 界面活性剤 / トムズ効果 / せん断誘起構造 / 蛍光 |
|---|
| Outline of Final Research Achievements |
When a small amount of a certain type of surfactant is added to the water flow in a pipe, drag is significantly reduced. In the drag-reducing surfactant flow, the surfactant molecules in the solution aggregate and form micelles. Furthermore, the micelles combine under the shearing flow and form large shear-induced structures (referred to as SIS). It is believed that this SIS suppresses the growth of turbulence and results in the drag reduction. However, detecting the SIS, which can only be formed under flow conditions, is extremely challenging. As a result, there are still many uncertainties regarding the relationship between drag reduction and SIS formation.
In this study, we added trace amounts of fluorescent material to the surfactant solution and detected the formation of SIS locally in the solution flow by fluorescence intensity. We also measured the flow velocity using a laser velocimeter to analyze the relationship among SIS formation, turbulent structure and drag reduction.
|
| Free Research Field |
流体工学
|
| Academic Significance and Societal Importance of the Research Achievements |
管内流にある種の界面活性剤を添加すると著しく抵抗が低減される．このような抵抗低減は，流動下で活性剤分子が集合し，巨大なせん断誘起構造(Shear Induced Structure，以後SISと表記)を形成するためであると考えられている．抵抗低減された流れでは乱れの成長が抑制されるが，SISがどこで，どのようなタイミングで生成・消滅し，乱れを抑制しているのかが不明であった．乱れの構造とSISの生成・消滅の関係を明らかにできれば，SISによる抵抗低減機構を明らかにできる学術的意義ある．また，より効果的な抵抗低減法を提案することが可能となり，省エネルギー社会の実現の一助となる社会的意義がある．
|
