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 × 102 < ReD < 2 × 104) 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 × 102 < ReD < 1 × 104. Cg was found to influence pressure drop performance to the greatest extent at low ReD, (<5 × 103), with the effect being significantly diminished by ReD = 1.5 × 104. 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.