Heat transfer from pin-fins situated in an oncoming longitudinal flow which turns to crossflow

Experiments were performed to determine per-fin heat transfer coefficients for pin-fin arrays exposed to a novel airflow arrangement. The flow enters the array longitudinally but, owing to the blocking action of the fin base surface, is forced to turn and exit the array with a predominantly crossflow orientation. Geometric parameters varied during the experiments included the fin height to diameter ratio H D and the inter-fin pitch to diameter ratio S D. For each geometric configuration, the Reynolds number was varied over an order of magnitude. In general, fins situated adjacent to the edges of the array have higher heat transfer coefficients than those situated in the interior of the array. The Nusselt numbers for the edge-adjacent fins are virtually independent of H D and S D when they are correlated with a Reynolds number based on a crossflow velocity. For the interior fins, a Reynolds number based on a longitudinal flow velocity was used to achieve a correlation which was insentitive to H D and S D. The pressure drop across the array was measured and presented in dimensionless form relative to a specially defined velocity head which gave a universal pressure drop result for all operating conditions.