Control of Heat and Momentum Transport Process by a Reversible Transform Micelle of Polymer

聚合物可逆转变胶束控制热量和动量传输过程

基本信息

批准号：
09650253
负责人：
HISHIDA Koichi
金额：
$ 2.05万
依托单位：
Keio 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

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650253/
关键词：
Laser technique Non-intrusive measurement Velocity measurement Shape measurement Non-spherical particle LDV PDA

项目摘要

It is well known that Thorns effect in non-Newtonian fluid causes the drag reduction. Recently it has been reported that an addition of small amounts of surfactants also provided the same effect on the drag reduction. The characteristics of drag reduction flow can transport the long distance thermal medium with low energy loss. The mechanism of drag reduction flow has been stilt unexplored, especially for the turbulent flow condition that appears in a practical application. In the present study, experimental study has been performed on the behavior of micelle structure with reversible transform of polymer, and a controlling technique for thermo-fluid phenomena has also developed by using surfactant.Heat transfer characteristics of a dilute surfactant/water solution in a two dimensional channel has been experimentally investigated. Temperature profile measurements in the thermal boundary layer were also made. It was found that high diffusivity layer exists near the wall in the drag reducing thermal boundary layer and that the time scale of temperature fluctuation in the layer becomes smaller as increased of wall heat flux. In order to increase the heat transfer coefficients, the mesh plug was used to exert high shear stress to destroy micelle structure in the surfactant solution so that turbulence could be produced. The mesh plug indicated that the high heat transfer region had the same turbulent intensity as that of water flow. The mesh helped to create high wall shear stress and therefore to destroy the rod-like micelles for introducing turbulent. It was found that the turbulent intensities of the velocity gradually decreased to the same as those of drag reduction flow downstream form the mesh because the mesh plug only produced a local high shear stress. This technique can be applied for effective heat transfer augmentation in a drag reduction flow.

众所周知，非牛顿流体中的荆棘效应会导致阻力减小。最近有报道称，添加少量表面活性剂也能提供相同的减阻效果。减阻流的特点可以长距离输送热介质，能量损失低。减阻流动的机理尚未被探索，特别是对于实际应用中出现的湍流条件。在本研究中，对聚合物可逆转变的胶束结构的行为进行了实验研究，并开发了利用表面活性剂的热流体现象的控制技术。稀表面活性剂/水溶液在溶液中的传热特性二维通道已被实验研究。还进行了热边界层中的温度分布测量。研究发现减阻热边界层中靠近壁面存在高扩散层，并且随着壁面热通量的增加，该层内温度波动的时间尺度变小。为了提高传热系数，利用网塞施加高剪切应力来破坏表面活性剂溶液中的胶束结构，从而产生湍流。网塞表明高传热区域具有与水流相同的湍流强度。网格有助于产生高壁剪切应力，从而破坏棒状胶束以引入湍流。结果发现，由于网塞仅产生局部高剪切应力，速度的湍流强度逐渐降低至与网下游减阻流相同。该技术可应用于减阻流中的有效传热增强。