Forced Convection Heat Transfer from a Finned Array with an Adjustable Outer Channel Boundary.

An analysis was made of the heat transfer characteristics of an array of longitudinal fins with an adjustable outer channel boundary and a constant heat flux into the base of the array. The channel boundary could be moved to provide fin tip clearance ratios from zero to twice the fin height. Velocity variations in the interfin space and the open channel adjacent to the fin tips caused a variation in the calculated heat transfer coefficients along the height of the finned array, with the maximum coefficient occuring in the region of maximum velocity. It was shown that fin tip heat loss was a function of the clearance between the fin tip and the outer channel boundary, and that the maximum heat loss could occur on or near the fin tip. It was also shown how the tip heat loss affected the heat transfer characteristics of the array. Centerline velocity profiles and streamline profiles developed for laminar flow with the finned array both heated and unheated. For the heated condition, two heat fluxes were used with three different clearance ratios. Temperature profiles within the fin were developed for the lower heat flux for both laminar and turbulent flow. Laminar flow results were compared to the analytical work of Acharya and Patankar.