Abstract This paper presents an experimental and numerical study of forced convection heat transfer from straight rectangular fins on a horizontal surface at low Reynolds numbers ranging from 2600 to 6800. Heat transfer for a fixed number of fins, fin spacing, and length was measured in a wind tunnel for varying inlet air velocity and heat input. Three-dimensional conjugate heat transfer simulations were also conducted to characterize important features of heat transfer and flow of the fin array and the effects of fin channel length on heat transfer. A maximum relative error of about 4.28% was found between the experimental and the numerical results for the average Nusselt number. The experimental results showed that forced convection heat transfer is characterized by an approximately linear relationship between the Nusselt and Reynolds numbers, which also agreed reasonably well with the available correlations for fully developed turbulent convective heat transfer for tubes with uniform heat flux. Further investigations of the effects of fin geometry were made numerically. Shorter fin channels, where the flow is thermally and hydrodynamically developing, were more effective in heat transfer than longer ones, where the flow approaches or reaches full development. It is shown that heat transfer rate per channel decreases linearly with the increase in channel length, but remains approximately constant with the increase in number of fins. It is also shown that the contributions of natural convection and radiation were negligible for the specific fin design and the range of inlet flow conditions and maximum fin temperature investigated here.

中文翻译：

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低雷诺数下矩形翅片强制对流换热的实验和数值研究

摘要 本文介绍了在 2600 到 6800 的低雷诺数下从水平表面上的直矩形翅片强制对流换热的实验和数值研究。固定翅片数量、翅片间距和长度的传热在风洞用于改变入口空气速度和热输入。还进行了三维共轭传热模拟，以表征翅片阵列的传热和流动的重要特征以及翅片通道长度对传热的影响。在平均努塞尔数的实验和数值结果之间发现了大约 4.28% 的最大相对误差。实验结果表明，强制对流换热的特点是努塞尔数和雷诺数之间存在近似线性关系，这也与具有均匀热通量的管的完全发展的湍流对流传热的可用相关性相当吻合。对翅片几何形状的影响进行了进一步的数值研究。较短的翅片通道，其中流动在热力和流体动力学上发展，在传热方面比较长的翅片通道更有效，其中流动接近或达到完全发展。结果表明，每通道的传热率随着通道长度的增加而线性下降，但随着翅片数量的增加而保持近似恒定。还表明，自然对流和辐射的贡献对于特定翅片设计以及此处研究的入口流动条件和最大翅片温度范围可以忽略不计。