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Passive control of jet flows using lobed nozzle geometries

Published online by Cambridge University Press:  11 July 2007

Ilinca Nastase  and
Amina Meslem
Ilinca Nastase
Affiliation:
LEPTAB, University of La Rochelle, Avenue Michel Crépeau 17042 La Rochelle Cedex 01, France
Amina Meslem
Affiliation:
LEPTAB, University of La Rochelle, Avenue Michel Crépeau 17042 La Rochelle Cedex 01, France
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Abstract

Passive control of the entrainment phenomenon in the turbulent jets is a mixing enhancement economical method of wide interest in the industrial field. A lobed nozzle without lobes inclinations allows improving mixing in the generated flow compared to a reference circular jet. A second lobed nozzle, having the same exit plane geometry but with inclined lobes intensifies, in a considerable manner, the entrainment which reaches up to four times the one in the reference circular jet. The lobed jets vortical dynamics analysis shows that the azimuthal structures are not annular like in the case of a circular jet, but discontinuous, due to the shear of the transverse flow induced by the curvature variation of the exit plane. The streamwise structures development at the discontinuities locations is probably explaining the entrainment benefit observed in the lobed jet without inclination angles. The lobed jet issued from the second nozzle presents like the first lobed jet, discontinuous azimuthal structures, but its remarkable induction benefit is not merely owed to the previous phenomenon. The intensification and organisation of the streamwise vorticity field into large scale structures, resulting in a consequent mixing enhancement, are connected to the increased shear produced by the lobes inclinations.

Keywords

Passive controllobed nozzleturbulent jetvortexmixingContrôle passifbuse lobéejet turbulentvortexmélange
Type
Research Article
Information
Mechanics & Industry , Volume 8 , Issue 2: Les journées AUM 2006, La Rochelle , March 2007 , pp. 101 - 109
Copyright
© AFM, EDP Sciences, 2007

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