绕流叶形截面管的流动、换热及性能分析

The Flow Drag and Heat Transfer of Flow across a Leaf-Shaped Pipe and Its Performance Analysis

本文对叶形截面管外的流动及换热进行了实验研究,获得了相应的准则关系式,并将其与圆形和椭圆形截面管进行了性能比较.结果显示出优于圆形管和椭圆管的传热与流动的综合性能,尤其是在高雷诺数情况下,综合性能更好.

The heat transfer and flow across a leaf-shaped pipe, whose cross section is like a leaf, has been investigated. Experiments have been made in a small wind tunnel and empirical relations of heat transfer and flow drag have been obtained. Compared with thoso obtained for circular and elliptic pipes, it is found that the heat transfer coefficient is lower than that for the circular pipe and higher than that for the elliptic pipe, but the flow drag is smallest. The exergy analyzing method has been used to assess the performance of the heat transfer and flow of the leaf-shaped pipe. On the basis of the equations of the exergy loss rate, it is shown that the performance of the leaf-shaped pipe is superior to that of the circular pipe with a given temperature difference or under the condition of higher velocity and smaller convective characteristic size.