The influence of Reynolds number on a plane jet

Deo, Ravinesh C., Mi, Jianchun and Nathan, G. J. (2008) The influence of Reynolds number on a plane jet. Physics of Fluids, 20 7: 075108-1-075108-16. doi:10.1063/1.2959171

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Author Deo, Ravinesh C.
Mi, Jianchun
Nathan, G. J.
Title The influence of Reynolds number on a plane jet
Journal name Physics of Fluids   Check publisher's open access policy
ISSN 0031-9171
1070-6631
Publication date 2008-07-22
Sub-type Article (original research)
DOI 10.1063/1.2959171
Open Access Status File (Publisher version)
Volume 20
Issue 7
Start page 075108-1
End page 075108-16
Total pages 17
Place of publication New York, United States
Publisher American Institute of Physics
Language eng
Subject 3104 Condensed Matter Physics
Abstract The present study systematically investigates through experiments the influence of Reynolds number on a plane jet issuing from a radially contoured, rectangular slot nozzle of large aspect ratio. Detailed velocity measurements were performed for a jet exit Reynolds number spanning the range 1500≤Re≤16 500, where Re ≡ Uh/ν with U as the momentum-averaged exit mean velocity, ha the slot height, and ν as the kinematic viscosity. Additional centerline measurements were also performed for jets from two different nozzles in the same facility to achieve Re = 57 500. All measurements were conducted using single hot-wire anemometry to an axial distance (x) of x≤160h. These measurements revealed a significant dependence of the exit and the downstream flows on Re despite all exit velocity profiles closely approximating a "top-hat" shape. The effect of Re on both the mean and turbulent fields is substantial for Re<10 000 but becomes weaker with increasing Re. The length of the jet's potential core, initial primary-vortex shedding frequency, and far-field rates of decay and spread all depend on Re. The local Reynolds number, Re ≡ 2Uy/ν, where U and y are the local centerline velocity and half-width, respectively, are found to scale as Re ∼ x. It is also shown that, for Re ≥ 1500, self-preserving relations of both the turbulence dissipation rate (ε) and smallest scale (η), i.e., ε ∼ Re(x/h) and η∼ Re(x/h), become valid for x/h ≥ 20.
Formatted abstract
The present study systematically investigates through experiments the influence of Reynolds number on a plane jet issuing from a radially contoured, rectangular slot nozzle of large aspect ratio. Detailed velocity measurements were performed for a jet exit Reynolds number spanning the range 1500 ≤ Reh ≤ 16 500, where Reh ≡ Ubh/υ with Ub as the momentum-averaged exit mean velocity, h as the slot height, and υ as the kinematic viscosity. Additional centerline measurements were also performed for jets from two different nozzles in the same facility to achieve Reh = 57 500. All measurements were conducted using single hot-wire anemometry to an axial distance (x) of x ≤ 160h. These measurements revealed a significant dependence of the exit and the downstream flows on Reh despite all exit velocity profiles closely approximating a “top-hat” shape. The effect of Reh on both the mean and turbulent fields is substantial for Reh<10 000 but becomes weaker with increasing Reh. The length of the jet’s potential core, initial primary-vortex shedding frequency, and far-field rates of decay and spread all depend on Reh. The local Reynolds number, Rey0.5 ≡ 2Ucy0.5/υ, where Uc and y0.5 are the local centerline velocity and half-width, respectively, are found to scale as Rey0.5 ∼ x1/2. It is also shown that, for Reh ≥ 1500, self-preserving relations of both the turbulence dissipation rate (ε) and smallest scale (η), i.e., ε ∼ Reh3(x/h)−5/2 and η ∼ Reh−3/4(x/h)5/8, become valid for x/h ≥ 20.
Keyword Fluid mechanics
Aircraft
Aerodynamics
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Geography, Planning and Environmental Management Publications
ERA 2012 Admin Only
 
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Citation counts: TR Web of Science Citation Count  Cited 35 times in Thomson Reuters Web of Science Article | Citations
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Created: Sat, 20 Jun 2009, 02:18:08 EST by Dr Ravinesh Deo on behalf of School of Geography, Planning & Env Management