Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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Effects of Rotation Speed on Heat Transfer and Flow in a Coolant Passage with Turning Region (II) - Parallel Ribbed Duct -

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

  • 김경민 (연세대학교 대학원 기계공학과) ;
  • 김윤영 (연세대학교 대학원 기계공학과) ;
  • 이동현 (연세대학교 대학원 기계공학과) ;
  • 조형희 (연세대학교 기계공학과)
  • Published : 2005.08.01
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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 ($D_h$) of 26.67 mm. Rib turbulators are attached in the parallel arrangement on the leading and trailing surfaces of the passage. The ribs have a rectangular cross section of 2 m (e) $\times$ 3 m (w) and an attack angle of $70^{\circ}$. The pitch-to-rib height ratio (p/e) is 7.5, and the rib height-to-hydraulic diameter ratio (e/$D_h$) 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 results show that a pair of vortex cells are generated due to the symmetric geometry of the rib arrangement, and heat/mass transfer is augmented up to $Sh/Sh_0=2.9$ averagely, which is higher than that of the cross-ribbed case presented in the previous study for the stationary case. With the passage rotation, the main flow in the first-pass deflects toward the trailing surface and the heat transfer is enhanced on the trailing surface. In the second-pass, the flow enlarges the vortex cell close to the leading surface, and the small vortex cell on the trailing surface side contracts to disappear as the passage rotates faster. At the highest rotation number ($R_O=0.20$), the turn-induced single vortex cell becomes identical regardless of the rib configuration so that similar local heat/mass transfer distributions are observed in the fuming region for the cross- and parallel-ribbed case.

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References

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