Heat transfer characteristics of turbulent flow in a square channel with angled discrete ribs
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Copyright © 1990 by ASME. Experiments have been conducted to study the turbulent heat transfer and friction for fully developed flow of air in a square channel in which two opposite walls are roughened with 90 0 full ribs, parallel and crossed full ribs with angles-of-attack (a) of 60° and 45 °, 90 0 discrete ribs, and parallel and crossed discrete ribs with = 60 °, 450, and 30°. The discrete ribs are staggered in alternate rows of three and two ribs. Results are obtained for a rib height-to-channel hydraulic diameter ratio of 0.0625, a rib pitch-to-height ratio of 10, and Reynolds ntnnbers between 10,000 and 80,000. Parallel angled discrete ribs are superior to 90 0 discrete ribs and parallel angled full ribs, and are recommended for internal cooling passages in gas turbine airfoils. For a= 60 ° and 45°, parallel discrete ribs have higher ribbed wall heat transfer, lower smooth wall heat transfer, and lower channel pressure drop than parallel full ribs. Parallel 60° discrete ribs have the highest ribbed wall heat transfer and parallel 30 0 discrete ribs cause the lowest pressure drop. The heat transfer and pressure drops in crossed angled full and discrete rib cases are all lower than those in the corresponding 90 0 and parallel angled rib cases. Crossed arrays of angled ribs have poor thermal performance and are not recommended.
author list (cited authors)
Lau, S. C., McMillin, R. D., & Han, J. C.