当量直径对超临界水流动传热特性的影响

以CFD商业软件FLUENT为计算平台，对圆管和圆环通道内超临界水流动传热特性进行数值模拟。通过对几种湍流模型的对比，选取在超临界条件下适用性相对较好的SST模型进行计算，分别比较不同热力当量直径和不同水力当量直径下圆管与圆环通道加热面壁温、边界层温度及速度的分布，研究热力当量直径和水力当量直径对超临界水流动传热特性的影响。结果表明，正常传热工况下，水力当量直径对超临界水流动传热特性有很大影响，而热力当量直径几乎无影响。圆环通道内流动传热关系式可基于圆管进行拟合，超临界水流动传热特性的其他影响因素还需进一步研究。

Influence of Equivalent Diameter on Heat Transfer and Flow Characteristics of Supercritical Water

A numerical simulation was carried out to study the heat transfer and flow characteristics of supercritical water in circular tube and annular channel using FLUENT software. According to the comparison of different turbulence models, SST model which is relatively better under supercritical condition was selected in this paper. Distributions of heated wall temperature, temperature and velocity in boundary layer in circular tube were compared with those in annular channel to study the influences of hydraulic equivalent diameter and thermal equivalent diameter on heat transfer and flow characteristics of supercritical water. The results show that hydraulic equivalent diameter plays an important role, while the influence of thermal equivalent diameter can be neglected.Correlations in annular channel can be established based on that in circular tube, and further researches should be carried out to study other impact factors on heat transfer and flow characteristics of supercritical water.