곡관부를 가지는 내부 냉각유로에서 회전수 변화에 따른 열전달 및 유동 특성 ( I ) - 엇갈린 요철배열 덕트 -

Abstract

The present study investigates heat/mass transfer and flow characteristics in a ribbed rotating passage with turning region. The duct has an aspect ratio (W/H) of 0.5 and a hydraulic diameter () of 26.67 mm. Rib turbulators are attached in the cross arrangement on the leading and trailing surfaces of the passage. The ribs have a rectangular cross section of and an attack angle of . The pitch-to-rib height ratio (p/e) is 7.5, and the rib height-to-hydraulic diameter ratio () is 0.075. The rotation number ranges from 0.0 to 0.20 while the Reynolds number is constant at 10,000. To verify the heat/mass transfer augmentation, internal flow structures are calculated for the same conditions using a commercial code FLUENT 6.1. The heat transfer data of the smooth duct for various Ro numbers agree well with not only the McAdams correlation but also the previous studies. The cross-rib turbulators significantly enhance heat/mass transfer in the passage by disturbing the main flow near the surfaces and generating one asymmetric cell of secondary flow skewing along the ribs. Because the secondary flow is induced in the first-pass and turning region, heat/mass transfer discrepancy is observed in the second-pass even for the stationary case. When the passage rotates, heat/mass transfer and flow phenomena change. Especially, the effect of rotation is more dominant than the effect of the ribs at the higher rotation number in the upstream of the second-pass.