布置球窝的U型冷却通道传热性能研究

Heat Transfer Performance of U-Shaped Coolant Channel with Dimple Structure

采用数值模拟方法研究了球窝结构对U型通道传热和阻力特性的影响,U型通道的一侧布置了球窝结构;采用SSTk-ω和大涡模拟(LES)湍流模型,对不同Re下的球窝强化传热性能进行了分析。结果表明:U型通道中第2列通道传热系数明显大于第1列通道,180°转弯角附近存在明显的二次流现象且传热系数较高;球窝结构的引入能明显强化U型通道的传热性能,球窝表面的平均Nu沿着流动方向逐渐减小,经过180°转弯角后急剧增大,球窝结构强化传热带来的压力损失非常小,几乎与光滑通道相当;RANS方法计算出的球窝表面Nu要大于LES方法的时均结果,相比LES方法,RANS方法判断的球窝腔内再附点更加靠近上游。

Numerical investigations were conducted to examine the heat transfer and friction performance of a U-shaped coolant channel with dimple structure on one surface of the channel. The SST k-ε turbulence model and the large eddy simulation （LES） were both adopted in the calculation to analyze the effect of dimple structure on the heat transfer performance at different Reynolds numbers. The results indicate that the heat transfer coefficient for the second row line in the U channel is much higher than that for the first row line, and the secondary flow exists near the 180°bend and the heat transfer rate is higher. Dimple structure can enhance the heat transfer process on the channel surface considerably. In the flow direction, the average Nu of the dimple surface decreases gradually, and it increases dramatically after the bend. Moreover, the pressure loss caused by dimple structure is small, almost approaching that of smooth channels. The Nu calculated by the SST model is slightly higher than that by the LES method, and the reattachment position obtained by the RANS method occurs earlier than that by the LES method.