Particle Image Velocimetry (PIV) was used to measure the flow field of staggered square pin fin array in a wide rectangle channel (AR=4). The experiment was conducted at two Reynolds number, 10000 and 20000, based on the hydraulic diameter and bulk velocity of the channel. In addition, the distribution of flow field properties was compared with that of Nu to analysis the key flow physics driving heat transfer enhancement. The Nusselt number was achieved through temperature measurement using thermochromic liquid crystal in the same geometry setup. These results were compare to circular pin fin with the same configuration to study the effect of geometry on flow physics driving heat transfer enhancement. It was found that the recirculation length of square pin fin is longer than that of circular pin fin, which indicated flow around square pin fin requires longer distance to develop. For square pin fin the shear layer unsteadiness on both sides plays a more important role on heat transfer enhancement, while for circular pin fin the cross-stream velocity fluctuation induced by large vortex shedding is the primary flow physics driving heat transfer augment. The relative importance of small scale unsteadiness and large scale vortex shedding to heat transfer augment is also affected by Reynolds number.

Investigation on Flow Mechanism Driving Heat Transfer Enhancement in a Wide Channel With Staggered Square Pin Fins

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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