Fluid Flow anf Heat Transfer Characteristics for Arrays of Heated Blocks

流动可视化是针对低雷诺数流体在沿平行板管道的一个壁沿着布置的加热方形块阵列中的流动进行的。这种配置模拟了在大规模集成元件中遇到的印刷电路板的强制对流冷却。珍珠掠流作为示踪剂用于流动显示。该问题的几何形状由块尺寸（L）、块厚度（B）、块间间隙（S）以及块与管道相对壁之间的流道高度（H）指定。实验针对B/L=3/8、S/L=1/4、H/L=1/4至5/8进行。通过流场显示得到的临界雷诺数范围为1000 ~ 1500，随管道高度的变化而变化，并对雷诺数为1900 ~ 5000时，加热块阵列的第h周期充分发展区和入口区的流动和传热特性进行了三维数值分析。湍流模型采用Lam和Bremhorst低雷诺数二方程模型。入口区的结果与实验结果进行了比较。周期性充分发展区的计算结果发表在《数值传热》上，进口区的计算结果发表在同一杂志上，采用Lam-Bremhorst低雷诺数程序，对雷诺数为100 ~ 2500的过渡区进行了三维数值分析。采用二方程湍流模型，得到了过渡区流体的流动和换热特性。测试的管道几何形状为B/L=3/8、S/L=1/4和H/L=1/4至5/8。因此，在H/L=5/8的情况下，从Re=700开始向湍流的转变。

The flow visualization was done for low Reynolds number fluid flow in an array of the heated square blocks deployed along one wall of the parallel plates duct. This configuration simulates the forced-convection cooling of printed circuit boards encountered in large scale integrated elements. The pearl graze was used for the flow visualization as a tracer. The geometry of the problem is specified by the block dimension (L), the block thicknes (B) , the inter-block gap (S) and the height of the flow passage between the block and the opposite wall of the duct ( H). The experiments were done for B/L=3/8, S/L=1/4, H/L=1/4 to 5/8. The critical Reynolds numbers obtained from the flow visualization were 1000 to 1500 depending on the height of the duct.Three-dimensional numerical analysis were conducted to obtain the fluid flow and heat transfer characteristics in both th periodic fully developed region and the entrance region of the array of the heated blocks for the range of Reynolds number from 1900 to 5000. Lam and Bremhorst low-Reynolds-number two equation model was used for the turbulent model. The results for the entrance region were compared with the experimental results. The result for the periodic fully developed region was published in the Numerical Heat Transfer and the result for the entrance region was accepted for publication in the same journal.Three-dimensional numerical analysis for the transition region of Reynolds number ranges from 100 to 2500 were conducted with using Lam-Bremhorst low-Reynolds-number two equation turbulence model to obtain the fluid flow and heat transfer characteristics in the transition region. The duct geometries tested were B/L=3/8, S/L=1/4 and H/L=1/4 to 5/8. As a consequence, in the case of H/L=5/8, the transition to the turbulent flow starts from Re=700.