Effect of Fin Pitch on Flow and Heat Transfer in Multilouvered Fins

High resolution time-dependent calculations are performed for developing flow and heat transfer in a multilouvered fin geometry to study the effect of fin pitch. In both cases, transition to unsteadiness occurs in the wake of the exit louver at a Reynolds number of 400. The upstream spatial propagation of instabilities proceeds much faster for the larger fin pitch. It is also found that the nature of instabilities differs between the two fin pitches. For the larger fin pitch, louver wake instabilities play a more dominant role than louver leading edge shear layer instabilities, which dominate the smaller fin pitch. Overall heat transfer increases per fin as the fin pitch increases because of the larger mass flow rate between fins. However, the difference in heat transfer coefficient between the two geometries is small except in the transitional and low Reynolds number range.Air Conditioning and Refrigeration Project 9