1998 Fiscal Year Final Research Report Summary
A Study on the Mechanism of Turbulence Controllability Caused by the Rod-like Micelles of Surfactants
| Project/Area Number |
09650833
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
化学工学一般
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| Research Institution | Kobe University |
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Principal Investigator |
USUI Hiromoto Kobe University, Department of Chemical Science and Engineering, Professor, 工学部, 教授 (20107725)
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| Co-Investigator(Kenkyū-buntansha) |
NANBARA Koji Kobe University, Department of Chemical Science and Engineering, Research Associ, 工学部, 助手 (00237637)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Drag Reduction / Energy / Surfactant / Turbulent Flow / Functional Fluid / Heat transfer / District Cooling System |
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| Research Abstract |
The addition of small amount of a cationic surfactant with suitable counter ion causes a drastic drag reduction in a turbulent pipe flow. The surfactant drag reduction experiments show that the large amount of drag reduction even in a large pipe diameter is obtained. The theological characteristics of surfactant solutions under considerably high shear rate is the key function for the turbulence control in a drag-reducing flow. Shear induced state, abbreviated in this report as SIS, is believed as a agglomerated state of rod-like micelles aliened by a shear field. SIS may cause a very large agglomerate structure of surfactants. The SIS was established at sufficiently high shear rate condition, and the shear rate was decreased linearly at fixed time derivative of shear rate. The shear stress response observed under such a shear history was simulated by using the relaxation function of Maxwell model. Very large relaxation time was obtained from the experimental results. The relaxation tim
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e was correlated by the time derivative of shear rate. This relaxation time was used to predict the surfactant drag reduction in pipe flow. The viscoelastic damping factor model previously proposed by Usui et al. was employed as a turbulence model. The shear viscosity experimentally determined under SIS was also used for this turbulence model. The drag reduction for different pipe diameter was successfully predicted by this model. Thus, it was finally concluded that drag reduction was quantitatively predictable by using the viscoelastic damping factor model with relaxation time and shear viscosity under SIS.
The above mentioned turbulence model was applied for the prediction of drag reduction in large scale pipeline systems. More than 80% drag reduction effectiveness was predicted for 1,000 mm pipe diameter case. The important conclusion is that the surfactant drag reduction is applicable to the full scale district heating and cooling systems. and the drag reduction effectiveness is predictable by the model proposed in this study.
This study was finally aimed to understand the mechanism of turbulent drag-reducing phenomenon The complete understanding of the mechanism is very difficult, and no one has succeeded in the past. The effort to understand the drag reduction mechanism must be continued in the future study. Less
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