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Influence of Turning Region and Channel Rotation on Pressure Drop in a Square Channel with Transverse Ribs

90° 요철이 설치된 정사각 덕트 내 압력강하에 곡관부 및 회전이 미치는 영향

  • 김경민 (연세대학교 대학원 기계공학부) ;
  • 이동현 (연세대학교 대학원 기계공학부) ;
  • 조형희 (연세대학교 기계공학부)
  • Published : 2006.02.01

Abstract

The pressure drop characteristics in a rotating two-pass duct with rib turbulators are investigated in the present study. The square duct has a hydraulic diameter $(D_h)$ of 26.7 mm, and $1.5mm{\times}1.5mm$ square $90^{\circ}-rib$ turbulators are attached on the leading and trailing walls. The pitch-to-rib height ratio (p/e) is 10. The distance between the tip of the divider and the outer wall of the duct is $1.0D_h$ and the width of divider wall is 6.0mm or $0.225D_h$. The Reynolds number (Re) based on the hydraulic diameter is kept constant at 10,000 to exclude the Reynolds effect, and the rotation number (Ro) is varied from 0.0 to 0.20. The pressure drop distribution, the friction factor and thermal performance are presented for the leading, trailing and the outer surfaces. It is found that the curvature of the $180^{\circ}$-turn produces Dean vortices that cause high pressure drop in the turn. The channel rotation results in pressure drop discrepancy between leading and trailing surfaces so that non-dimensional pressure drops are higher on the trailing surface in the first-pass and on the leading and side surfaces in the second-pass. In the turning region, Dean vortices shown in the stationary case transform into one large asymmetric vortex cell, and subsequent pressure drop characteristics also change. As the rotation number increases, the pressure drop discrepancy enlarges.

Keywords

References

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