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

The Korean Society of Mechanical Engineers (대한기계학회)
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Characteristics of Turbulent Impinging and Wall Jet Flow for a Circular Nozzle with Various Exit Wall Thickness

다양한 벽면 두께를 갖는 원형 노즐에서 분사되는 난류 충돌 및 벽면 제트 유동장 특성

  • Yang, Geun-Yeong (Institude of Advanced Machinery and Design, Seoul National University) ;
  • Yun, Sang-Heon (Dept.of Mechanical Engineering, Graduate School of Seoul National University) ;
  • Son, Dong-Gi (Institude of Advanced Machinery and Design, Seoul National University) ;
  • Choe, Man-Su
  • 양근영 (서울대학교 정밀기계설계공동연구소) ;
  • 윤상헌 (서울대학교 대학원 기계공학과) ;
  • 손동기 (서울대학교 정밀기계설계공동연구소) ;
  • 최만수
  • Published : 2001.06.01
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Abstract

An experimental study of impinging jet-flow structure has been carried out for a fully developed single circular jet impingement cooling on a flat plate, and the effect of the wall thickness at nozzle exit edge is investigated. Impinging jet flow structures have been measured by Laser-Doppler Velocimeter to interpret the heat transfer results presented previously by Yoon et al.(sup)(10) The peaks of heat transfer rate are observed near the nozzle edge owing to the radial acceleration of jet flow when the nozzle locates close to the impingement plate. The growth of the velocity fluctuations in the wall jet flow is induced by the vortices which originate in the jet shear layer, and consequently the radial distribution of local Nusselt numbers has a secondary peak at the certain radial position. As a wall of circular pipe nozzle becomes thicker for small nozzle-to-target distance, the entrainment can be inhibited, consequently, the acceleration of wall jet flow is reduced and the heat transfer rate decreases.

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References

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