Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference

In this work we experimentally investigate the behavior of stable vortex breakdown taking place in a coaxial swirling jet with a density difference, highlighting the effect of the outer jet on the height of the stagnation point. With increasing bulk flow velocity of the outer jet, the degree of flow...

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Main Authors: A., Adzlan, H., Gotoda
Format: Article
Language:English
Published: Elsevier Ltd 2012
Subjects:
Online Access:http://ir.unimas.my/id/eprint/3003/
http://ir.unimas.my/id/eprint/3003/1/1-s2.0-S0009250912003089-main%20-%20cutted.pdf
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author A., Adzlan
H., Gotoda
author_facet A., Adzlan
H., Gotoda
author_sort A., Adzlan
building UNIMAS Institutional Repository
collection Online Access
description In this work we experimentally investigate the behavior of stable vortex breakdown taking place in a coaxial swirling jet with a density difference, highlighting the effect of the outer jet on the height of the stagnation point. With increasing bulk flow velocity of the outer jet, the degree of flow divergence decreases, resulting in an increase in the height of the stagnation point. This is due to a significant increase in the mean axial velocity along the centerline of the jet, which is clearly shown by particle image velocimetry (PIV). We proposed an equation to physically explain the height of the stagnation point in a coaxial swirling jet with a density difference undergoing vortex breakdown, by considering an estimate of the momentum balance in the flow, based on a simplified Navier–Stokes equation for coaxial jets with coannular flow. Even though the effect of the density difference on the height of the stagnation point is overestimated by the proposed equation, the increase with respect to the Reynolds number of the outer jet observed experimentally is in reasonably good qualitative agreement with the trend predicted by the theoretical model.
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spelling unimas-30032017-03-02T01:11:57Z http://ir.unimas.my/id/eprint/3003/ Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference A., Adzlan H., Gotoda TP Chemical technology In this work we experimentally investigate the behavior of stable vortex breakdown taking place in a coaxial swirling jet with a density difference, highlighting the effect of the outer jet on the height of the stagnation point. With increasing bulk flow velocity of the outer jet, the degree of flow divergence decreases, resulting in an increase in the height of the stagnation point. This is due to a significant increase in the mean axial velocity along the centerline of the jet, which is clearly shown by particle image velocimetry (PIV). We proposed an equation to physically explain the height of the stagnation point in a coaxial swirling jet with a density difference undergoing vortex breakdown, by considering an estimate of the momentum balance in the flow, based on a simplified Navier–Stokes equation for coaxial jets with coannular flow. Even though the effect of the density difference on the height of the stagnation point is overestimated by the proposed equation, the increase with respect to the Reynolds number of the outer jet observed experimentally is in reasonably good qualitative agreement with the trend predicted by the theoretical model. Elsevier Ltd 2012 Article NonPeerReviewed text en http://ir.unimas.my/id/eprint/3003/1/1-s2.0-S0009250912003089-main%20-%20cutted.pdf A., Adzlan and H., Gotoda (2012) Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference. Chemical Engineering Science, 80. pp. 174-181. ISSN 0009-2509 http://www.sciencedirect.com/science/article/pii/S0009250912003089
spellingShingle TP Chemical technology
A., Adzlan
H., Gotoda
Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference
title Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference
title_full Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference
title_fullStr Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference
title_full_unstemmed Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference
title_short Experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference
title_sort experimental investigation of vortex breakdown in a coaxial swirling jet with a density difference
topic TP Chemical technology
url http://ir.unimas.my/id/eprint/3003/
http://ir.unimas.my/id/eprint/3003/
http://ir.unimas.my/id/eprint/3003/1/1-s2.0-S0009250912003089-main%20-%20cutted.pdf