Local Heat Transfer Characteristics in Channels With Pin Fin and Pin Fin-Dimple Arrays

A comparative study was conducted to investigate the spatially-resolved local heat transfer characteristics of air turbulent flow in rectangular channels with pin fin and pin fin-dimple arrays. The spatially-resolved Nusselt numbers on the endwall surface of the pin fin and pin fin-dimple channels have been obtained and compared with each other. Compared with the pin fin channel, the pin fin-dimple channel shows distinguishing heat transfer characteristics on the wall beneath the main flow and the wake flow region. Due to the presence of the dimples in the pin fin arrays, additional strong vortex flows are generated near the wall beneath the main flow region, which distinctively increase the heat transfer rates there; however the turbulent mixing in the wake of the pin fins is reduced appreciably, which leads to decreased heat transfer rates in the wake.