高温气冷堆中间换热器层流边界层的传热特性分析

摘要

为提高高温气冷堆中间换热器的换热效率，对中间换热器单元流道的层流流动边界层及热边界层进行了理论计算和模拟分析。利用幂次多项式速度分布的方法，对流道内的层流流动边界层和热边界层进行计算，结果表明，三次式的速度分布更为接近Blasius精确解，也更为符合数值模拟的结果。同时，结合不同位置的温度分布，可发现上、下边界层的相遇会使流动进入泊肃叶的抛物线形式，边界层理论继而不再适用。通过模拟还发现，氦气的进口温度和出口压力对于层流边界层的换热基本无影响；恒定热流密度下，壁面温度的变化分为明显的边界层区和泊肃叶区，在这两个区域壁面温度呈线性变化。%To improve the heat efficiency of the high-temperature gas-cooled reactor intermediate heat exchanger , the theoretical calculation and simulation analysis of laminar flow and thermal boundary layers for the IHX were carried out .Through the way of polynomial velocity distribution ,it is found that a third order polynomial velocity distribution is close to the Blasius exact solution and the results of the numerical simulation .At the same time ,combined with the temperature distribution in different locations ,it is found that upper and lower boundary layers will meet .And then ,the flow changes to the Poiseuille flow and the boundary layer theory no longer applies .At last ,the effects of He inlet temperature and outlet pressure were analyzed ,which makes no difference .Under constant heat flux ,the changes of wall temperature can be divided into obvious boundary layer zone and Poiseuille flow zone and in both areas are linear .