Effect of non-traditional rib-profiles on heat transfer and friction in turbulent channel flows

Abstract

AIAA, Thermophysics Conference, 31st, New Orleans, LA, June 17-20, 1996 An experimental study with computational verification of wall heat transfer and friction characteristics of a fully-developed turbulent air flow in a rectangular channel with transverse ribs of non-traditional profiles is reported. Tests were performed for Reynolds numbers ranging from 14,000 to 90,000. The pitch-to-rib height ratio was kept at 10 and the rib height-to-channel hydraulic diameter ratio was kept at 0.125. The channel length-to-hydraulic diameter ratio was 20. The heat transfer coefficient and friction factor values were enhanced using turbulators of different shapes: square, circular, triangular, slant edged, and semicircular. The channel with square ribs produces the highest heat transfer augmentation and pressure drop. The friction roughness function was almost constant over the entire range of tests performed and was within comparable limits of previously published data. The heat transfer roughness function also compared well with previous work. The computational analysis was in close agreement with experimental results and prior computational work. Results of this investigation could be used in various applications of channel turbulent flows involving different shape rib-profiles on roughened walls. (Author)