凹陷涡发生器形状对湍流流动与传热性能的影响

Influence of Dimple Shapes on Turbulent Flow and Heat Transfer

利用数值计算方法研究了分别具有球形、椭球形、倾斜椭球形以及泪滴形凹陷涡发生器阵列表面的湍流传热与流阻性能.采用湍流模型Relizable k-ε、SST（Shear Stress Transportation）和Standard k-ω模拟凹陷涡发生器表面的湍流传热与流阻性能,并与其实验结果进行对比,确定了Standard k-ω是研究凹陷传热和流动的最精确湍流模型.同时,通过数值计算分析了4种凹陷结构在雷诺数为8 500-60 000下的传热、流阻和流动特性,利用Matlab软件对数值计算结果进行后处理.结果表明：与充分发展的光滑通道内湍流流动相比,球形凹陷通道的传热性能提高了约40%,摩擦因子增加了约70%;椭球形凹陷通道的传热性能提高了约30%,摩擦因子增加了60%左右;倾斜椭球形凹陷通道的传热性能提高了约40%,摩擦因子增加了60%左右;泪滴形凹陷通道的传热性能提高了约70%,摩擦因子增加了约1倍,即泪滴形凹陷通道的传热性能和综合热性能最佳。

Dimples are very effective structures to enhance heat transfer. Based on numerical simulations, this paper investigated the heat transfer and friction factor of sphere, eliptical, inclined eliptical and tear-drop dimple. Comparisons of the heat transfer and friction factor results obtained by using the Relizable k-ω, SST, and Standard k-ω models with the experimental results indicate that the Standard k-ω model can best predict the flow and heat transfer in the dimpled channels. The heat transfer and flow structure char- acteristics in the four dimpled channels have been obtained and compared with each other for the Reynolds numbers of 8 500 to 60 000. The Matlab software is used in this paper to process the numerical data to get the heat transfer distribution along the streamwise direction. The study shows that compared to the flat channel, the sphere dimple enhances the heat transfer by 40% and the friction factor by 70%; the eliptical dimple enhances the heat transfer by 30% and the friction factor by 60%;the inclined eliptical dimple en- hances the heat transfer by 40 % and the friction factor by 60 % ; and the teardrop dimple enhances the heat transfer by 70% and the friction factor by 100%. Generally speaking, the teardrop dimple has the best heat transfer and overall performance.