Turbulent heat transfer in the thermal entrance region of a pipe with uniform heat flux
Turbulent heat transfer in the thermal entrance region of a pipe with uniform heat flux
复制标题
均匀热通量管道热入口区域的湍流传热
DOI：
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发表时间：
1957
期刊：
影响因子：
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通讯作者：
R. Siegel
中科院分区：
文献类型：
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作者：
E. Sparrow;T. M. Hallman;R. Siegel
使用类似于 Graetz 的层流热入口区域公式的方法进行了分析。假设流体在整个管道长度上具有充分发展的湍流速度分布。对于普朗特数在 0.7 到 100 之间、雷诺数在 50000 到 500000 之间的流体，提供局部和完全展开的努塞尔数。热入口长度定义为使局部努塞尔数达到完全展开值的 5% 以内所需的加热长度。发现该长度随着普朗特数的增加而减小，从普朗特数为 0.7 时的约 10 个直径下降到普朗特数为 100 时的小于 1 个直径。与使用积分法-边界层方法的 Deissler 的结果以及可用的实验数据进行了比较。通过将当前的均匀热通量结果与之前考虑均匀壁温的研究人员的结果进行比较，研究了热边界条件的影响。
An analysis has been performed using a method similar to Graetz’s formulation for the laminar thermal entry region. The fluid is assumed to have a fully developed turbulent velocity profile throughout the length of the pipe. Local and fully developed Nusselt numbers are presented for fluids with Prandtl numbers ranging from 0.7 to 100 for Reynolds numbers between 50000 and 500000. A thermal entrance length is defined as the heated length required to bring the local Nusselt number to within 5 percent of the fully developed value. This length is found to decrease with increasing Prandtl number, dropping from about 10 diameters for a Prandtl number of 0.7 to less than one diameter for a Prandtl number of 100. Comparison is made with the results of Deissler, who used an integral method-boundary layer approach, and also with available experimental data. The effect of the thermal boundary conditions was studied by comparing the present uniform heat flux results with those of previous investigators who considered uniform wall temperature.