Spatial DNS of flow transition of a rectangular buoyant reacting free jet (in special issue on Second International Symposium on Turbulence and Shear Flow Phenomena)
Spatial DNS of flow transition of a rectangular buoyant reacting free jet (in special issue on Second International Symposium on Turbulence and Shear Flow Phenomena)
This paper describes a spatial direct numerical simulation (DNS) of the flow transition of a buoyant diffusion flame established on a rectangular nozzle with an aspect ratio of 2:1. Combustion is represented by a one-step finite-rate Arrhenius chemistry. Without applying external perturbations, large vortical structures develop naturally in the flow field due to buoyancy effects. The vortex dynamics of the rectangular buoyant reacting jet has been analysed. The interaction between density gradients and gravity initiates the flow vorticity in the cross-streamwise directions. The streamwise vorticity is mainly generated by the vortex stretching. Downstream of the reacting jet, a more disorganized flow regime characterized by small scales has been observed, following the breakdown of the large vortical structures due to three-dimensional vortex interactions. Analysis of the energy spectra shows that the spatially developing reacting jet has a tendency of transition to turbulence under the effects of combustion-induced buoyancy. Buoyancy effects are found to be very important to the formation, development, interaction and breakdown of vortices. In contrast with the relaminarization effects of chemical exothermicity on non-buoyant jet diffusion flames via volumetric expansion and viscous damping, the tendency towards transition to turbulence in buoyant reacting jets is greatly enhanced by the overwhelming buoyancy effects. Calculations of the mean flow property show that the rectangular buoyant reacting jet has a higher entrainment rate than its non-reacting counterpart.
1-18
Jiang, X.
008a11fa-f330-4355-b5c6-2878d1ab0f5c
Luo, K.H.
1c9be6c6-e956-4b12-af13-32ea855c69f3
2001
Jiang, X.
008a11fa-f330-4355-b5c6-2878d1ab0f5c
Luo, K.H.
1c9be6c6-e956-4b12-af13-32ea855c69f3
Jiang, X. and Luo, K.H.
(2001)
Spatial DNS of flow transition of a rectangular buoyant reacting free jet (in special issue on Second International Symposium on Turbulence and Shear Flow Phenomena).
Journal of Turbulence, 2 (15), .
(doi:10.1088/1468-5248/2/1/015).
Abstract
This paper describes a spatial direct numerical simulation (DNS) of the flow transition of a buoyant diffusion flame established on a rectangular nozzle with an aspect ratio of 2:1. Combustion is represented by a one-step finite-rate Arrhenius chemistry. Without applying external perturbations, large vortical structures develop naturally in the flow field due to buoyancy effects. The vortex dynamics of the rectangular buoyant reacting jet has been analysed. The interaction between density gradients and gravity initiates the flow vorticity in the cross-streamwise directions. The streamwise vorticity is mainly generated by the vortex stretching. Downstream of the reacting jet, a more disorganized flow regime characterized by small scales has been observed, following the breakdown of the large vortical structures due to three-dimensional vortex interactions. Analysis of the energy spectra shows that the spatially developing reacting jet has a tendency of transition to turbulence under the effects of combustion-induced buoyancy. Buoyancy effects are found to be very important to the formation, development, interaction and breakdown of vortices. In contrast with the relaminarization effects of chemical exothermicity on non-buoyant jet diffusion flames via volumetric expansion and viscous damping, the tendency towards transition to turbulence in buoyant reacting jets is greatly enhanced by the overwhelming buoyancy effects. Calculations of the mean flow property show that the rectangular buoyant reacting jet has a higher entrainment rate than its non-reacting counterpart.
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Published date: 2001
Additional Information:
This article was chosen from selected Proceedings of the Second International Symposium on Turbulence and Shear Flow Phenomena (KTH-Stockholm, 27-29 June 2001) ed E. Lindborg, A. Johansson, J. Eaton, J. Humphrey, N. Kasagi, M. Leschziner and M. Sommerfeld
Identifiers
Local EPrints ID: 23104
URI: http://eprints.soton.ac.uk/id/eprint/23104
ISSN: 1468-5248
PURE UUID: 9b325e7e-e689-4da8-bbbe-9dcd0a6d610b
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Date deposited: 28 Mar 2006
Last modified: 15 Mar 2024 06:44
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Author:
X. Jiang
Author:
K.H. Luo
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