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

本文从理论和实验两方面研究了流体层与流体饱和多孔层之间的流动和传热机理。将具有不锈钢箔表面的垂直板放置在流体层和多孔层中，并通过不锈钢箔供应电力来加热。在界面附近的温度场，可视化的Mach-Zehnder干涉仪，揭示了温度梯度突然变化的接口，和热点附近的角落出现的流动再循环。因此，它已被证明，可以有效地显示界面附近的温度场的马赫-郑德干涉仪。利用热线风速仪和烟丝流动显示装置研究了多孔方杆的非定常绕流。在不同的雷诺数和达西数下测量了底部压力、阻力系数和斯特罗哈数。是的 ...更多信息 EN发现，通过多孔棒的流动形成向前流动区域，将再循环区推向下游。Strouhal数似乎是相当不敏感的雷诺数和达西数，并保持几乎恒定的实验范围内。随着雷诺数的增加，前向流区扩大，回流区向下游移动，而Darg系数则随着Darcy数的增加而减小。本文还对垂直饱和多孔柱的瞬态流动与传热进行了理论和实验研究。将小珠多孔柱连接到水箱，控制水箱以保持a。恒压头使用与放置在柱底部的阀同步的钨丝电路来产生氢气泡。用高速摄像机监测气泡的运动，用胶片运动分析仪分析气泡的瞬时速度。建立了一维非达西渗流模型，并将计算结果与实验结果进行了比较，验证了模型的正确性。该模型揭示了非达西孔隙惯性作用使速度水平和达到稳态速度水平所需的时间减小，而这个时间常数强烈地依赖于渗透率，与压头差无关，因此，多孔介质中的非稳态流动行为以及与多孔介质之间的界面相关的流动和传热特性，和流体层进行了充分的探索。少

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