Heat transfer performance of U-shaped coolant channel with dimple structure

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-ω 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.