Karlovitz number effects on velocity and scalar statistics in turbulent premixed combustion
Karlovitz number effects on velocity and scalar statistics in turbulent premixed combustion
Velocity and scalar statistics are obtained from a series of Direct Numerical Simulations of low Mach number spatially-evolving turbulent premixed planar jet flames. In these simulations, the bulk Reynolds number and stoichiometric equivalence ratio are fixed, and the Karlovitz number is adjusted by varying the global strain rate. Hydrogen combustion with detailed transport is modeled using a detailed nine-species chemical kinetic mechanism, and coflows of combustion products are used to ensure flame stability at uniform equivalence ratio. From these simulations, velocity and scalar statistics are obtained conditioned on progress variable. The analysis of these statistics focuses on two key areas. First, theoretical arguments indicate that pressure-dilatation work becomes a significant source of turbulent kinetic energy in low Karlovitz number flames, which has been confirmed previously. In this work, the relative importance of the pressure-dilatation term versus other terms in the turbulent kinetic energy budget is expected to decrease with increasing Karlovitz number, and this will be directly assessed with the DNS databases. Second, the degree of alignment between the Reynolds stresses (scalar fluxes) and the strain rate (scalar gradient), the foundation of a majority of the turbulence models used in reacting flows, is expected to depend on Karlovitz number and will be assessed with the DNS databases.
Budgets, Karlovitz number, Scalar variance, Turbulent kinetic energy
MacArt, Jonathan F.
1384a548-486e-4fae-9d5c-4177b0ed7825
Grenga, Temistocle
be0eba30-74b5-4134-87e7-3a2d6dd3836f
Mueller, Michael E.
de069534-2aa2-4382-a380-0f3fdbfc6526
2017
MacArt, Jonathan F.
1384a548-486e-4fae-9d5c-4177b0ed7825
Grenga, Temistocle
be0eba30-74b5-4134-87e7-3a2d6dd3836f
Mueller, Michael E.
de069534-2aa2-4382-a380-0f3fdbfc6526
MacArt, Jonathan F., Grenga, Temistocle and Mueller, Michael E.
(2017)
Karlovitz number effects on velocity and scalar statistics in turbulent premixed combustion.
10th U.S. National Combustion Meeting, , College Park, United States.
23 - 26 Apr 2017.
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Conference or Workshop Item
(Paper)
Abstract
Velocity and scalar statistics are obtained from a series of Direct Numerical Simulations of low Mach number spatially-evolving turbulent premixed planar jet flames. In these simulations, the bulk Reynolds number and stoichiometric equivalence ratio are fixed, and the Karlovitz number is adjusted by varying the global strain rate. Hydrogen combustion with detailed transport is modeled using a detailed nine-species chemical kinetic mechanism, and coflows of combustion products are used to ensure flame stability at uniform equivalence ratio. From these simulations, velocity and scalar statistics are obtained conditioned on progress variable. The analysis of these statistics focuses on two key areas. First, theoretical arguments indicate that pressure-dilatation work becomes a significant source of turbulent kinetic energy in low Karlovitz number flames, which has been confirmed previously. In this work, the relative importance of the pressure-dilatation term versus other terms in the turbulent kinetic energy budget is expected to decrease with increasing Karlovitz number, and this will be directly assessed with the DNS databases. Second, the degree of alignment between the Reynolds stresses (scalar fluxes) and the strain rate (scalar gradient), the foundation of a majority of the turbulence models used in reacting flows, is expected to depend on Karlovitz number and will be assessed with the DNS databases.
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Published date: 2017
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Funding Information:
The authors gratefully acknowledge valuable support in the form of computational time on the TIGRESS high performance computer center at Princeton University, which is jointly supported by the Princeton Institute for Computational Science and Engineering (PICSciE) and the Princeton University Office of Information Technology's Research Computing department.
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© 2017 Eastern States Section of the Combustion Institute. All rights reserved.
Venue - Dates:
10th U.S. National Combustion Meeting, , College Park, United States, 2017-04-23 - 2017-04-26
Keywords:
Budgets, Karlovitz number, Scalar variance, Turbulent kinetic energy
Identifiers
Local EPrints ID: 480918
URI: http://eprints.soton.ac.uk/id/eprint/480918
PURE UUID: 74f53046-a5fe-4882-a03d-e58572a3487c
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Date deposited: 10 Aug 2023 16:57
Last modified: 06 Jun 2024 02:16
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Contributors
Author:
Jonathan F. MacArt
Author:
Temistocle Grenga
Author:
Michael E. Mueller
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