Heat transfer and pressure drop in flow passages that are open along their lateral edges

Abstract

Passage-average and local heat transfer coefficients and overall pressure drops were measured for both laminar and turbulent flow in a rectangular passage open along its lateral edges and closed at its downstream end. Parametric variations were made of the Reynolds number, the interwall spacing, and the passage configuration. For the latter, the inlet and exit fluid flow areas were: (1) both fully open, (2) half blocked at inlet, open at exit, and (3) half blocked at exit, open at inlet. The objective of the shrouding (i.e. the partial blockages) was to encourage the flow to penetrate into the downstream portion of the passage and, thereby, to promote the streamwise uniformity of the local transfer coefficient. For the unshrouded passage, the passageaverage heat transfer coefficient increased by about 40% in response to a halving of the interwall spacing. The Reynolds number dependence of the transfer coefficient obeyed two distinct power laws, respectively for the high and low Reynolds number ranges. Partial shrouding of the inlet increased the passage-average transfer coefficient by 25–40% at the higher Reynolds numbers, while side shrouding yielded 10–15% enhancement at the lower Reynolds numbers. Streamwise uniformity of the local transfer coefficient was promoted by shrouding and by increases in the interwall spacing and the Reynolds number. The overall pressure drop increased in the presence of shrouding.