上游边界层对向上散热的水平热板自然对流换热影响的研究

EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF UPSTREAM BOUNDARY LAYER ON NATURAL CONVECTION HEAT TRANSFER OF A HEATED UPWARD FACING SURFACE

论文对具有上游边界层场合的水平加热表面向上对流换热的自然对流进行了实验研究,采用全息干涉法测定温度场,对侧壁高度为50,100,150毫米三种情况进行了实验测定,发现其边缘效应与无侧壁时的水平板情况不同,在6×10~3<Gr_xPr<5×10~6即紊流区,给出了平均Nu数和局部Nu数的准则关系式,这些公式,适用于上述参数和水平板不小于100毫米的场合。

The heat transfer from heated upward facing horizontal surfaces with various degree of influences of upstream boundary layers are inyestigeted experimentally, k reveals that the edge effect on heat transfer for cases with upstream boundary layers are in most eases contrary to that of the simple heated upward facing surfaces. New heat transfer correlations are recommended both for local and for average Nusselt numbers in the range of GrxPr =6 ×103-5× 106. Comparison of the experimental data with the numerical results in literature indicates that the hypothesis of using flow path length as characteristic dimension is valid only for special cases where height H is dominant in the flow path but fails to predict the heat transfer in more general cases.