Local Heat/Mass Transfer Phenomena in Rotating Passage, Part 1: Smooth Passage

Abstract

Mass transfer experiments and numerical computations are conducted to investigate the heat/mass transfer and flow characteristics in a rotating passage with a 180-deg turn. In the present study, rectangular 70-deg rib turbulators are attached in cross and parallel arrangements on the leading and trailing surfaces of the passage. The cross-sectional area of the passage is 20 x 40 mm2, and the pitch-to-rib height ratio (pie) is 7.5. The rotation number ranges from 0.0 to 0.20, whereas the Reynolds number is constant at 10,000. The results reveal that the angled rib turbulators enhance significantly heat/mass transfer in the rotating two-pass duct by generating a secondary flow. For the cross-ribbed passage, a heat/mass transfer discrepancy is observed in the second pass even for the stationary case because one asymmetric cell of secondary flow is induced in the first pass and turning region. For the parallel-ribbed passage, the flow and heat/mass transfer characteristics are less subject to the rotation number than those of the former case due to the different flow structure. At the highest tested rotation number (Ro = 0.20), the turn-induced single vortex cell becomes identical regardless of the rib configuration so that the local heat/mass transfer distributions are similar in the turning region for all of the test sections.