A novel split-dimple interrupted fin configuration for heat transfer augmentation

The use of an interrupted plate fin with surface roughness in the form of split-dimples is investigated. High-fidelity time-dependent calculations are performed for a wide range of Reynolds number ranging from ReH = 240 to 4000, covering the laminar to fully turbulent flow regimes. The split-dimples provide an additional mechanism for augmenting heat transfer by perturbing continuous boundary layer formation on the fin surface and generating energetic shear layers. High heat transfer regions are observed at the fin and split-dimple leading edges as a result of boundary layer restarts, in regions of flow acceleration between protrusions, and flow impingement on the protrusion surface. While the protruding geometry of the split-dimple also aids in augmenting heat transfer from the fin surface by generating unsteady or turbulent wakes, it also increases pressure losses. The split-dimple fin results in a heat conductance that is 60-175% higher than a plain interrupted plate fin, but at a cost of 4-8 times the frictional losses.