Effect of Tip Clearance on the Thermal and Hydrodynamic Performance of a Shrouded Pin Fin Array

Abstract

The effect of introducing tip clearance to a liquid cooled array of shrouded pins fins is examined. Three arrays of height to diameter ratio ranging from 0.5 to 1.1 were evaluated experimentally. The arrays were exposed to a uniform heat flux of 0.02 to 0.26 W/mm2 and cooled with water through a nominal Reynolds number range of 200 to 10,000. Tip clearance of 0 to 25% of pin height was assessed. Mean heat transfer rates and adiabatic pressure drop across the array were determined and empirical correlations are proposed. The introduction of clearance was seen to increase overall heat transfer in some cases.

Numerical investigation on heat transfer of liquid flow at low Reynolds number in micro-cylinder-groups

“…11 and 13. As discussed by Sparrow [12], the wall boundary layer thickness extends a few micro-cylinder diameters from the wall at lower Re number, and strongly affect the hydrodynamic field (endwall effect), so the total flow channel is immersed in the fluid for the micro-cylinder-groups investigated in present paper (0.5 B H/D B 2). Thus, the velocity gradients near the wall in micro-cylinder-groups increase rapidly with the decrease of micro-cylinder heights, so the fluid velocity at the particular location is higher in micro-cylinder-groups with taller height than the shorter ones; as a result the heat transfer is enhanced.…”

“…In many cases, the increase in the flow temperature resulted in a convection thermal resistance, which was considerably smaller than the total thermal resistance. Moores et al [12][13][14] investigated the effect of tip clearance on thermal and hydrodynamic performance in micro pin fins, and gave the correlation to predict the influence of tip clearance on Nu and friction factors in micro pin fins. Naphon et al [15] experimentally and numerically investigated the heat transfer characteristics of in-line and staggered taper pin fin heat sink under constant heat flux conditions.…”

Influence of heating load on heat transfer characteristics in micro-pin-fin arrays

“…About this subject, Moores et al [16][17][18] investigated the effect of tip clearance on thermal and hydrodynamic performance in micro pin fins, and gave the correlation to predict the influence of tip clearance on Nu and friction factor in micro pin fins. Besides, Reinhard et al [19] evaluated the heat transfer in straight silicon microchannels with integrated in-line and staggered pin fin arrays at clearance to diameter ratios of 0.50-0.77 in the laminar flow regime at Re numbers ranging from 9.0 to 246.…”

Vortex distribution and mixed convection of liquid flow across micro-cylinders in a rectangular channel

“…At the same time, high efficient cooling technique in micro and mini spaces are requested due to the increasing power and the compactness of electronic elements. Based on this requirement, micro-cylinder-groups (pin fins) have been paid a lot of attentions in recent years as an efficient cooling structure, and many researchers [1][2][3][4][5][6][7][8][9][10] carried out various investigations on the flow and heat transfer characteristics in this structure.…”