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A Study on the Mechanism of Turbulence Controllability Caused by the Rod-like Micelles of Surfactants

表面活性剂棒状胶束引起湍流可控性机理的研究

基本信息

批准号：
09650833
负责人：
USUI Hiromoto
金额：
$ 2.11万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

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 … More 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

添加少量阳离子表面活性剂和合适的反离子可使湍流管流中的阻力显著降低。表面活性剂减阻实验表明，在大管径下也能获得较大的减阻效果。表面活性剂溶液在高剪切速率下的流变特性是减阻流中湍流控制的关键。剪切诱导态，在本报告中简称为SIS，被认为是一个团聚状态的棒状胶束在剪切场的排列。SIS可引起表面活性剂的非常大的附聚物结构。SIS建立在足够高的剪切速率条件下，并且剪切速率在固定的时间导数下线性减小。利用麦克斯韦模型的松弛函数模拟了在这种剪切历史下观察到的剪切应力响应。从实验结果中得到了很大的弛豫时间。放松时间 ...更多信息 e与剪切速率的时间导数相关。该弛豫时间被用来预测表面活性剂在管流中的减阻。湍流模型采用先前由Alfrei等人提出的粘弹性阻尼因子模型。在SIS下实验测定的剪切粘度也用于该湍流模型。该模型成功地预测了不同管径的减阻效果。最后得出结论，SIS条件下的粘弹性阻尼因子模型可以定量预测减阻效果，并将该湍流模型应用于大规模管道系统的减阻预测。在1,000 mm管径的情况下，减阻效果可达80%以上.重要结论是表面活性剂减阻适用于全尺寸区域供热和供冷系统。本研究的最终目的是了解湍流减阻现象的机理。对湍流减阻机理的完全理解是非常困难的，过去还没有人成功。在今后的研究中，必须继续努力了解减阻机理。少