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

The Korean Society of Mechanical Engineers (대한기계학회)
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Heat Transfer Characteristics on Impingement Surface with Control of Axisymmetric Jet ( 2 ) - With Acoustic Excitation -

원형제트출구 전단류 조절에 따른 제트충돌면에서의 열전달 특성 ( 2 ) - 음향여기된 제트 -

  • 황상동 (연세대학교 대학원 기계공학과) ;
  • 이창호 (연세대학교 대학원 기계공학과) ;
  • 조형희 (연세대학교 기계공학과)
  • Published : 2000.03.01
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Abstract

The flow and heat transfer characteristics on the impingement surface can be controlled by the change of vortex with the acoustic excitation, because the flow characteristics of an impinging jet are affected strongly by the vortices formed at the jet exit. To investigate the effects of acoustic excitation, we measured the velocity, turbulent intensity distributions for the free jet and local heat transfer coefficients on a impingement surface. As the acoustic excitation, subharmonic frequency of excited frequency plays an important role to the control of the jet flow. If the vortex pairings are promoted by the acoustic excitation, turbulence intensity of the jet flow is increased quickly. On the other hand if the vortex pairings are suppressed, the jet flow has low turbulence intensity at the center of the jet. Therefore, the low heat transfer rates are obtained on the impingement plate for a small nozzle-to-plate distance. However, it has high heat transfer rates at a large distance between the nozzle and plate due to the increasing of potential-core length.

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References

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