Heat Transfer Characteristics in a Pin Finned Channel With Different Dimple Locations

Abstract

A numerical simulation is conducted to investigate effects of dimple locations on the flow structure and heat transfer in a dimpled-pin finned channel. Pin fins are arranged with a staggered layout on the endwall surface. The dimple print diameter is the same as the pin fin diameter. Five different dimple locations are investigated in this study. All results are acquired at Reynolds numbers ranging from 8,500 to 60,000. The results show that the dimple locations have remarkable effects on the flow structure and heat transfer in a dimpled-pin finned channel. The Nusselt number of the dimpled-pin finned channel is only increased by 3.52%, while the friction factor is increased by 1.81% compared to the pure pin finned channel when the dimple is located in the wake region. The wake and reversed flow are responsible for this low heat transfer augmentation. When the dimple is located in between the two pin fins, the counter-rotating vortex and impingement within the dimple produce the highest Nusselt number and the lowest friction factor among the tested dimple locations. In this case, the Nusselt number is increased by 20.94% and the friction factor is decreased by 1.69% compared to the pure pin finned channel.