The influence of Reynolds number on a plane jet

Deo, Ravinesh C. and Mi, Jianchun and Nathan, Graham J. (2008) The influence of Reynolds number on a plane jet. Physics of Fluids, 20 (7). 075108-1. ISSN 1070-6631

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


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Author's version not held. Article number 075108
Depositing User: Dr Ravinesh C Deo
Faculty / Department / School: Historic - Faculty of Sciences - Department of Maths and Computing
Date Deposited: 15 Apr 2010 06:16
Last Modified: 08 Sep 2014 06:07
Uncontrolled Keywords: plane jet; Reynolds number effect; vortex shedding; jet mixing and entrainment
Fields of Research (FOR2008): 09 Engineering > 0901 Aerospace Engineering > 090101 Aerodynamics (excl. Hypersonic Aerodynamics)
09 Engineering > 0915 Interdisciplinary Engineering > 091508 Turbulent Flows
09 Engineering > 0915 Interdisciplinary Engineering > 091504 Fluidisation and Fluid Mechanics
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Identification Number or DOI: doi: 10.1063/1.2959171
URI: http://eprints.usq.edu.au/id/eprint/7428

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