On the Role of Chemical Kinetics Modeling in the LES of Premixed Bluff Body and Backward-Facing Step Combustors

Handle URI:
http://hdl.handle.net/10754/623575
Title:
On the Role of Chemical Kinetics Modeling in the LES of Premixed Bluff Body and Backward-Facing Step Combustors
Authors:
Chakroun, Nadim W.; Shanbhogue, Santosh J.; Kewlani, Gaurav; Taamallah, Soufien; Michaels, Dan; Ghoniem, Ahmed
Abstract:
Recirculating flows in the wake of a bluff body, behind a sudden expansion or down-stream of a swirler, are pivotal for anchoring a flame and expanding the stability range. The size and structure of these recirculation zones and the accurate prediction of the length of these zones is a very important characteristic that computational simulations should have. Large eddy simulation (LES) techniques with an appropriate combustion model and reaction mechanism afford a balance between computational complexity and predictive accuracy. In this study, propane/air mixtures were simulated in a bluff-body stabilized combustor based on the Volvo test case and also in a backward-facing step combustor. The main goal is to investigate the role of the chemical mechanism and the accuracy of estimating the extinction strain rate on the prediction of important ow features such as recirculation zones. Two 2-step mechanisms were employed, one which gave reasonable extinction strain rates and another modi ed 2-step mechanism where it grossly over-predicted the values. This modified mechanism under-predicted recirculation zone lengths compared to the original mechanism and had worse agreement with experiments in both geometries. While the recirculation zone lengths predicted by both reduced mechanisms in the step combustor scale linearly with the extinction strain rate, the scaling curves do not match experimental results as none of the simpli ed mechanisms produce extinction strain rates that are consistent with those predicted by the comprehensive mechanisms. We conclude that it is very important that a chemical mechanism is able to correctly predict extinction strain rates if it is to be used in CFD simulations.
Citation:
Chakroun NW, Shanbhogue SJ, Kewlani G, Taamallah S, Michaels D, et al. (2017) On the Role of Chemical Kinetics Modeling in the LES of Premixed Bluff Body and Backward-Facing Step Combustors. 55th AIAA Aerospace Sciences Meeting. Available: http://dx.doi.org/10.2514/6.2017-1572.
Publisher:
American Institute of Aeronautics and Astronautics (AIAA)
Journal:
55th AIAA Aerospace Sciences Meeting
Conference/Event name:
55th AIAA Aerospace Sciences Meeting
Issue Date:
5-Jan-2017
DOI:
10.2514/6.2017-1572
Type:
Conference Paper
Sponsors:
Financial support from the King Abdullah University of Science and Technology (KAUST), the King Fahd University of Petroleum and Minerals (KFUPM), and the TATA Center for Design and Research, is gratefully acknowledged.
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorChakroun, Nadim W.en
dc.contributor.authorShanbhogue, Santosh J.en
dc.contributor.authorKewlani, Gauraven
dc.contributor.authorTaamallah, Soufienen
dc.contributor.authorMichaels, Danen
dc.contributor.authorGhoniem, Ahmeden
dc.date.accessioned2017-05-15T10:35:09Z-
dc.date.available2017-05-15T10:35:09Z-
dc.date.issued2017-01-05en
dc.identifier.citationChakroun NW, Shanbhogue SJ, Kewlani G, Taamallah S, Michaels D, et al. (2017) On the Role of Chemical Kinetics Modeling in the LES of Premixed Bluff Body and Backward-Facing Step Combustors. 55th AIAA Aerospace Sciences Meeting. Available: http://dx.doi.org/10.2514/6.2017-1572.en
dc.identifier.doi10.2514/6.2017-1572en
dc.identifier.urihttp://hdl.handle.net/10754/623575-
dc.description.abstractRecirculating flows in the wake of a bluff body, behind a sudden expansion or down-stream of a swirler, are pivotal for anchoring a flame and expanding the stability range. The size and structure of these recirculation zones and the accurate prediction of the length of these zones is a very important characteristic that computational simulations should have. Large eddy simulation (LES) techniques with an appropriate combustion model and reaction mechanism afford a balance between computational complexity and predictive accuracy. In this study, propane/air mixtures were simulated in a bluff-body stabilized combustor based on the Volvo test case and also in a backward-facing step combustor. The main goal is to investigate the role of the chemical mechanism and the accuracy of estimating the extinction strain rate on the prediction of important ow features such as recirculation zones. Two 2-step mechanisms were employed, one which gave reasonable extinction strain rates and another modi ed 2-step mechanism where it grossly over-predicted the values. This modified mechanism under-predicted recirculation zone lengths compared to the original mechanism and had worse agreement with experiments in both geometries. While the recirculation zone lengths predicted by both reduced mechanisms in the step combustor scale linearly with the extinction strain rate, the scaling curves do not match experimental results as none of the simpli ed mechanisms produce extinction strain rates that are consistent with those predicted by the comprehensive mechanisms. We conclude that it is very important that a chemical mechanism is able to correctly predict extinction strain rates if it is to be used in CFD simulations.en
dc.description.sponsorshipFinancial support from the King Abdullah University of Science and Technology (KAUST), the King Fahd University of Petroleum and Minerals (KFUPM), and the TATA Center for Design and Research, is gratefully acknowledged.en
dc.publisherAmerican Institute of Aeronautics and Astronautics (AIAA)en
dc.titleOn the Role of Chemical Kinetics Modeling in the LES of Premixed Bluff Body and Backward-Facing Step Combustorsen
dc.typeConference Paperen
dc.identifier.journal55th AIAA Aerospace Sciences Meetingen
dc.conference.date2017-01-09 to 2017-01-13en
dc.conference.name55th AIAA Aerospace Sciences Meetingen
dc.conference.locationGrapevine, TX, USAen
dc.contributor.institutionMassachusetts Institute of Technology, Department of Mechanical Engineering, 77 Massachusetts Ave., Cambridge, MA 02139, United Statesen
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.