Upstream nozzle shaping effects on near field flow in round turbulent free jets

doi:10.1016/j.euromechflu.2005.10.002

European Journal of Mechanics - B/Fluids

Volume 25, Issue 3, May–June 2006, Pages 279-301

https://doi.org/10.1016/j.euromechflu.2005.10.002 Get rights and content

Abstract

Isothermal, incompressible round turbulent free jets of air, issuing from a sharp-edged orifice and from a contoured nozzle into still air surroundings, have been used to study the effects of upstream nozzle shaping on near field jet evolution experimentally. The Reynolds number, based on the diameter of the orifice or the nozzle, was $1.84 \times 10^{5}$ in both jets. Hot-wire anemometry and a pitot-static tube were used to obtain the measured quantities which included the mean streamwise velocity, the turbulent Reynolds normal and shear stresses, the autocorrelation coefficients and one-dimensional energy spectra of the fluctuating streamwise velocity and the mean static pressure. The mean streamwise velocity decay on the jet centerline and the jet half-velocity widths were obtained from the mean streamwise velocity data. To the extent that the results showed that mixing in the sharp-edged orifice round jet was higher than in the contoured nozzle round jet, upstream nozzle shaping was found to affect jet evolution in the near flow field. The distribution of the autocorrelation coefficients of the streamwise fluctuating velocity showed a marked difference in the evolution of the two jets, one of which had a uniform, and the other a non-uniform, exit plane mean streamwise velocity profile. The one-dimensional energy spectra results and also those of the distribution of the autocorrelation coefficients indicated the presence of coherent structures in the near field of the jets and the sharp-edged orifice jet was found to be more “energetic” than the contoured nozzle jet.

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Citation Excerpt :
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Upstream nozzle shaping effects on near field flow in round turbulent free jets

Abstract

Int. J. Heat Fluid Flow

Some measurements in the self-preserving jet

J. Fluid Mech.

A new method of analyzing hot-wire signals in highly turbulent flow, and its evaluation in a round jet

DISA Info

Turbulence measurements in axisymmetric jets of air and helium. Part 1: Air Jet

J. Fluid Mech.

Turbulent Jets

Boundary-Layer Theory

Jet diffusion in the region of flow establishment

J. Fluid Mech.

Measurement of local entrainment rate in the initial region of axisymmetric turbulent air jets

J. Fluid Mech.

Flow structure of the free round turbulent jet in the initial region

J. Fluid Mech.

The near field behaviour of round jets at moderate Reynolds numbers

Canad. J. Chem. Engrg.

Mixing characteristics of axisymmetric free jets from a contoured nozzle, an orifice plate and a pipe

J. Fluids Engrg.