An experimental and numerical study of flow and heat transfer in channels with pin fin-dimple and pin fin arrays

摘要

An experimental and numerical study was conducted to investigate the flow friction and heat transfer performance in rectangular channels with staggered arrays of pin fin-dimple hybrid structures and pin fins in the Reynolds number range of 8200-54,000. The study aims at improving the cooling design for the gas turbine components. The friction factor, Nusselt number and the overall thermal performance parameters of the pin fin-dimple and the pin fin channels have been obtained and compared with the experimental data of a smooth rectangular channel and previously published data of the pin fin channel. The comparisons showed that, compared with the pin fin channel, the pin fin-dimple channel has further improved convective heat transfer performance by about 8.0% and whereas lowered flow friction by more than 18.0%. In addition, fully three-dimensional numerical computations have been done to investigate the physical details about the flow and heat transfer in the pin fin and pin fin-dimple channels. The computations showed that the dimples increase the near-wall turbulent mixing level by producing strong vortex flows, and therefore enhance the convective heat transfer in the channel. On the other hand, the dimples enlarge the minimum cross section area transversely between the pin fins, and therefore the pressure loss in the flow can be reduced in the pin fin-dimple channels.