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

The Korean Society of Mechanical Engineers (대한기계학회)
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Flow Structure Around a Rectangular Prism Placed in a Thick Turbulent Boundary Layer

두꺼운 난류경계층 내부에 놓인 직사각형 프리즘 주위의 유동구조

  • 김경천 (부산대학교 기계공학부) ;
  • 지호성 (부산테크노파크 부산대학교 분소부산대학교 대학원 기계공학과) ;
  • 추재민 (한국에너지기술연구원, 폐열이용 연구센터) ;
  • 이석호 (부산대학교 기계공학부) ;
  • 성승학
  • Published : 2002.04.01
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Abstract

Flow structures around a rectangular prism have been investigated by using a PIV(Particle Image Velocimetry) technique. A thick turbulent boundary layer was generated by using spires arid roughness elements. The boundary layer thickness, displacement thickness and momentum thickness were 650mm, 117.4mm and 78mm, respectively. The ratio between the model height(40mm) and the boundary layer thickness H/$\delta$, was 0.06. The Reynolds number based on the free stream velocity and the height of the model was 7.9$\times$10$^3$. The PIV measurements were performed at three different wall normal planes. Three recirculation regions at forward facing step, top of the roof and backward facing step are clearly seen and show three dimensional features. Dramatic changes of flow patterns are observed in the wake regions in the different spanwise wall normal planes. Instead of reattachment and recirculation zone, rising streamlines are depicted at the normal planes near the side wall due to the interaction with a rising horse shoe vortex. The peak of turbulent kinetic energy occurs at the separation bubble on top of the roof and the magnitude is 2.5 times higher compared with that of the wake region.

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References

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