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Flow and heat transfer mechanism in the vicinity of the interface between the porous and fluid layers

多孔层和流体层界面附近的流动和传热机制

基本信息

批准号：
01550172
负责人：
NAKAYAMA Akira
金额：
$ 1.09万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550172/
关键词：
Porous media Darcy flow Non-Darcy flow Visualization of temperature field Flow visualization Finite difference Karman vortex Square rod 流水の可視化非定常流熱移動干渉計数値解析自然対流複合材

项目摘要

A theoretical and experimental study has been conducted to invesitigate the flow and heat transfer mechanism associated with the interface between the fluid layer and the fluid-saturated porous layer. A vertical plate with stainlesss foil surfaces was placed in the fluid and porous layers and heated up by supplying electric power through the stainless foils. The temperature filed in the vicinity of the interface, visualized by the Mach-Zehnder interferometer, reveals that the temperature gradient changes abruptly at the interface, and a hot spot appears near the corner where the flow recirculates. Thus, it has been demonstrated that the temperature field near the interface can be visualized effectively by means of Mach-Zhender interferometer. Unsteady flows around a porous square rod were also investigated using a hot wire anemoseter and smoke-wire flow visualization device. Base pressure, drag coefficient and Strouhal number were measured changing Reynolds and Darcy numbers. It has be … More en found that the flow passing through the porous rod forms a forward flow region, pushing the recirculationg zone downstream. The Strouhal number appears to be fairly insensitive to the Reynolds and Darcy numbers, and remains almost constant within the experimental range. It is also found that the forward flow region expands, and push the recirculation zone farther downstream, as the Reynolds number increases, while the darg coefficient decreases as increasing the Darcy number. Transient flow and heat transfer through a vertical fluid-saturated porous column was also investigated theoretically and experimentally, . The porous column of small beads was connected to the water tank which was controlled to, keep a. constant pressure head. A tungsten wire circuit synchronized with the valve placed at the bottom of the column was used to produce hydrogen bubbles. The bubble notion was monitored by a high speed camera, and analyzed to find the instantaneous velocity by a film motion analyzer. A onedimensional non-Darcy flow model has been proposed and the numerical results are compared against the experimental data to substantiate the validity of the model. The model reveals that the non-Darcy Porous inertia works to decrease the velocity level and the time required for reaching the steady state velocity level, and this time constant depends strongly on the perseabilty, irrespectively of the difference in the pressure head.Thus, the unsteady flow behavior in porous media and the flow and heat transfer characteristics associated with the interface between the porous, and fluid layers have been fully explored through the present study. Less

进行了理论和实验研究，探讨了流体层与流体饱和多孔层之间的界面流动和换热机理。在流体层和多孔层中放置一个带有不沾污箔表面的垂直板，并通过不锈钢箔提供电力来加热。马赫-曾德尔干涉仪显示的界面附近的温度场表明，界面处的温度梯度发生突变，在流体回流的拐角附近出现了一个热点。结果表明，利用马赫-曾德尔干涉仪可以有效地显示界面附近的温度场。利用热线风速仪和烟丝流动显示装置对多孔方棒周围的非定常流动进行了研究。通过改变雷诺数和达西数，测量了底压、阻力系数和斯特劳哈尔数。这就是…进一步研究发现，流经多孔杆的流体形成了一个正向流动区，将回流区推向下游。Strouhal数对雷诺数和达西数几乎不敏感，在实验范围内几乎保持不变。随着雷诺数的增大，前向流区扩大，回流区向下游推进，达格系数随达西数的增大而减小。文中还从理论和实验两方面研究了垂直流体饱和多孔柱的瞬时流动与换热。小球多孔柱与水箱相连，水箱控制恒压水头。与放置在塔底部的阀门同步的钨丝电路被用来产生氢气泡。气泡概念由高速摄像机监控，并通过胶片运动分析仪进行分析以求出瞬时速度。提出了一维非达西流模型，并将计算结果与实验数据进行了比较，验证了该模型的有效性。该模型表明，非达西多孔惯量的作用是降低速度水平和达到稳态速度水平所需的时间，并且这一时间常数强烈地依赖于渗透率，而与压头差无关。因此，通过本文的研究，充分探讨了多孔介质中的非稳态流动行为以及与多孔和流体层之间的界面的流动和换热特性。较少