Crossref journal-article
Cambridge University Press (CUP)
Journal of Fluid Mechanics (56)
Abstract

Measurements in the mixing region of a 1 in. diameter cold air jet are described for Mach numbers ranging from 0.2 to 0.55. The statistical characteristics of the turbulence in the first few diameters of the flow may be expressed in terms of simple kinematic similarity relationships. These are based on the jet diameter and the distance downstream from the jet orifice as length-scales, and the inverse of the local shear as a time-scale. The experiments show that the integral time scale of the turbulence in a frame convected with the maximum energy of the turbulent motion is inversely proportional to the local shear.The most interesting result obtained is that the local intensity of the turbulence is equal to 0.2 times the shear velocity. This velocity is defined as the product of the local integral length-scale of the turbulence with the local shear. The local intensity is defined as the R.M.S. value of the local velocity fluctuations divided by the jet efflux velocity. It was found that the length-scale is proportional to the distance from the jet orifice, while the maximum shear is also related to this distance as well as to the jet efflux velocity. These two similarity relations break down close to the jet orifice and change beyond the first six or so diameters downstream. The convection velocity is not equal to the local mean velocity but varies slowly over the region of maximum shear when it is just over half the jet efflux velocity. The measurements of other observers fit the relationships obtained quite well. From these relationships it is possible to calculate the noise generated by the mixing region of a given jet directly, using expressions derived by Lilley (1958).

Bibliography

Davies, P. O. A. L., Fisher, M. J., & Barratt, M. J. (1963). The characteristics of the turbulence in the mixing region of a round jet. Journal of Fluid Mechanics, 15(3), 337–367.

Authors 3
  1. P. O. A. L. Davies (first)
  2. M. J. Fisher (additional)
  3. M. J. Barratt (additional)
References 21 Referenced 278
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Dates
Type When
Created 19 years, 5 months ago (March 28, 2006, 6:08 a.m.)
Deposited 6 years, 4 months ago (April 17, 2019, 1:02 p.m.)
Indexed 2 months, 1 week ago (June 21, 2025, 4:02 a.m.)
Issued 62 years, 6 months ago (March 1, 1963)
Published 62 years, 6 months ago (March 1, 1963)
Published Online 19 years, 5 months ago (March 28, 2006)
Published Print 62 years, 6 months ago (March 1, 1963)
Funders 0

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@article{Davies_1963, title={The characteristics of the turbulence in the mixing region of a round jet}, volume={15}, ISSN={1469-7645}, url={http://dx.doi.org/10.1017/s0022112063000306}, DOI={10.1017/s0022112063000306}, number={3}, journal={Journal of Fluid Mechanics}, publisher={Cambridge University Press (CUP)}, author={Davies, P. O. A. L. and Fisher, M. J. and Barratt, M. J.}, year={1963}, month=mar, pages={337–367} }