Heat transfer and fluid flow in shrouded pin fin arrays with and without tip clearance

Shrouded pin fin arrays with tip clearances (Cg) up to 25% of pin height were experimentally evaluated. Pressure loss was measured (2 x 10(2) < Re(D) < 2 x 10(4)) and liquid crystal thermography was employed to obtain temperature distributions from which the impact of Cg on the mean heat transfer rate was determined for 2 x 10(2) < Re(D) < 1 x 10(4). Cg was found to influence pressure drop performance to the greatest extent at low Re(D), (<5 x 10(3)), with the effect being significantly diminished by Re(D) = 1.5 x 10(4). On a per unit pumping power basis, higher heat transfer rates were observed for dimensionless clearances (Cg/D) less than 0.2 as compared to the non-clearance case. (C) 2009 Elsevier Ltd. All rights reserved.