中国物理B ›› 2011, Vol. 20 ›› Issue (12): 124701-124701.doi: 10.1088/1674-1056/20/12/124701

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Influences of initial velocity, diameter and Reynolds number on a circular turbulent air/air jet

米建春, 杜诚   

  1. State Key Laboratory of Turbulence and Complex Systems, Peking University, Beijing 100871, China;Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China
  • 收稿日期:2011-04-20 修回日期:2011-07-15 出版日期:2011-12-15 发布日期:2011-12-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 10921202 and 11072005).

Influences of initial velocity, diameter and Reynolds number on a circular turbulent air/air jet

Mi Jian-Chun(米建春)a)b)† and Du Cheng(杜诚)a)b)   

  1. a State Key Laboratory of Turbulence and Complex Systems, Peking University, Beijing 100871, China; b Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China
  • Received:2011-04-20 Revised:2011-07-15 Online:2011-12-15 Published:2011-12-15
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 10921202 and 11072005).

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摘要： This paper assesses the suitability of the inflow Reynolds number defined by Reo ≡ UoD/ν (here Uo and D are respectively the initial jet velocity and diameter while ν is kinematic viscosity) for a round air/air jet. Specifically an experimental investigation is performed for the influences of Uo, D and Reo on the mean-velocity decay and spread coefficients (Ku, Kr) in the far field of a circular air jet into air from a smoothly contracting nozzle. Present measurements agree well with those previously obtained under similar inflow conditions. The relations Ku ∝ Uo and Kr ∝ 1/Uo for Uo < 5 m/s appear to work, while each coefficient approaches asymptotically to a constant for Uo > 6 m/s, regardless of the magnitudes of Reo and D. It is revealed that Reo may not be an appropriate dimensionless parameter to characterize the entire flow of a free air/air jet. This paper is the first paper that has challenged the suitability of Reo for turbulent free jets.

关键词: turbulent jet, momentum conservation, Reynolds number

Abstract: This paper assesses the suitability of the inflow Reynolds number defined by Reo ≡ UoD/$\nu$ (here Uo and D are respectively the initial jet velocity and diameter while $\nu$ is kinematic viscosity) for a round air/air jet. Specifically an experimental investigation is performed for the influences of Uo, D and Reo on the mean-velocity decay and spread coefficients (Ku, Kr) in the far field of a circular air jet into air from a smoothly contracting nozzle. Present measurements agree well with those previously obtained under similar inflow conditions. The relations Ku ∝ Uo and Kr ∝ 1/Uo for Uo < 5 m/s appear to work, while each coefficient approaches asymptotically to a constant for Uo > 6 m/s, regardless of the magnitudes of Reo and D. It is revealed that Reo may not be an appropriate dimensionless parameter to characterize the entire flow of a free air/air jet. This paper is the first paper that has challenged the suitability of Reo for turbulent free jets.

Key words: turbulent jet, momentum conservation, Reynolds number

中图分类号:  (Turbulent flows)

  • 47.27.-i
47.27.wg (Turbulent jets)