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Fluid age-based analysis of a lifted turbulent DME jet flame DNS

Fluid age-based analysis of a lifted turbulent DME jet flame DNS
Fluid age-based analysis of a lifted turbulent DME jet flame DNS
The link between the distribution of fluid residence time and the distribution of reactive scalars is analysed using Direct Numerical Simulation data. Information about the reactive scalar distribution is needed in order to model the reaction terms that appear in Large Eddy and Reynolds-Averaged simulations of turbulent reacting flows. The lifted flame is simulated taking account of multi-step chemistry for dimethyl-ether fuel. Due to autoignition and flame propagation, the reaction progress increases with residence time. The variation of fluid residence time is evaluated by solving an Eulerian transport equation for the fluid age. The fluid age is a passive scalar with a spatially-uniform source term, meaning that its moments and dissipation rates in turbulent flows can be modelled using closures already established for conserved scalars such as mixture fraction. In combination with the mixture fraction, the fluid age serves as a useful mapping variable to distinguish younger less-reacted fluid near the inlet from older more-reacted fluid downstream. The local fluctuations of mixture fraction and fluid age have strong negative correlation and, building upon established presumed-pdf models for mixture fraction, this feature can be used to construct an accurate presumed-pdf model for the joint mixture fraction/fluid age pdf. It is demonstrated that the double-conditional first-order moment closure combined with the proposed presumed model for the joint pdf of mixture fraction and fluid age gives accurate predictions for unconditional reaction rates – both for pre-ignition radical species produced by low-temperature processes upstream of the flame base, and for major species that are produced at the flame front.
1540-7489
Shin, Dong-hyuk
aefc1292-87fd-48ab-94bc-a857692ccabe
Richardson, Edward
a8357516-e871-40d8-8a53-de7847aa2d08
Aparace-Scutariu, Vlad
db3cb9b2-47a4-4b6f-8502-56ac8016c8f7
Minamoto, Yuki
b3765e85-e0fc-42af-afd6-0e043f1b9a89
Chen, Jacqueline H.
0fae559d-60be-4456-847e-43372476d0e1
Shin, Dong-hyuk
aefc1292-87fd-48ab-94bc-a857692ccabe
Richardson, Edward
a8357516-e871-40d8-8a53-de7847aa2d08
Aparace-Scutariu, Vlad
db3cb9b2-47a4-4b6f-8502-56ac8016c8f7
Minamoto, Yuki
b3765e85-e0fc-42af-afd6-0e043f1b9a89
Chen, Jacqueline H.
0fae559d-60be-4456-847e-43372476d0e1

Shin, Dong-hyuk, Richardson, Edward, Aparace-Scutariu, Vlad, Minamoto, Yuki and Chen, Jacqueline H. (2018) Fluid age-based analysis of a lifted turbulent DME jet flame DNS. Proceedings of the Combustion Institute, 37. (doi:10.1016/j.proci.2018.06.126).

Record type: Article

Abstract

The link between the distribution of fluid residence time and the distribution of reactive scalars is analysed using Direct Numerical Simulation data. Information about the reactive scalar distribution is needed in order to model the reaction terms that appear in Large Eddy and Reynolds-Averaged simulations of turbulent reacting flows. The lifted flame is simulated taking account of multi-step chemistry for dimethyl-ether fuel. Due to autoignition and flame propagation, the reaction progress increases with residence time. The variation of fluid residence time is evaluated by solving an Eulerian transport equation for the fluid age. The fluid age is a passive scalar with a spatially-uniform source term, meaning that its moments and dissipation rates in turbulent flows can be modelled using closures already established for conserved scalars such as mixture fraction. In combination with the mixture fraction, the fluid age serves as a useful mapping variable to distinguish younger less-reacted fluid near the inlet from older more-reacted fluid downstream. The local fluctuations of mixture fraction and fluid age have strong negative correlation and, building upon established presumed-pdf models for mixture fraction, this feature can be used to construct an accurate presumed-pdf model for the joint mixture fraction/fluid age pdf. It is demonstrated that the double-conditional first-order moment closure combined with the proposed presumed model for the joint pdf of mixture fraction and fluid age gives accurate predictions for unconditional reaction rates – both for pre-ignition radical species produced by low-temperature processes upstream of the flame base, and for major species that are produced at the flame front.

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Fluid_Age_based_Analysis_of_a_Lifted_Turbulent_DME_Jet_Flame_DNs - Accepted Manuscript
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Accepted/In Press date: 16 June 2018
e-pub ahead of print date: 3 July 2018

Identifiers

Local EPrints ID: 422086
URI: http://eprints.soton.ac.uk/id/eprint/422086
ISSN: 1540-7489
PURE UUID: 7ff377dc-cb20-4851-99b3-6d27295612dc

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Date deposited: 16 Jul 2018 16:30
Last modified: 22 Nov 2021 06:31

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Contributors

Author: Dong-hyuk Shin
Author: Vlad Aparace-Scutariu
Author: Yuki Minamoto
Author: Jacqueline H. Chen

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