Mode Transition and Intermittency in an Acoustically Uncoupled Lean Premixed Swirl-Stabilized Combustor

Handle URI:
http://hdl.handle.net/10754/598848
Title:
Mode Transition and Intermittency in an Acoustically Uncoupled Lean Premixed Swirl-Stabilized Combustor
Authors:
LaBry, Zachary A.; Taamallah, Soufien; Kewlani, Gaurav; Shanbhogue, Santosh J.; Ghoniem, Ahmed F.
Abstract:
The prediction of dynamic instability remains an open and important issue in the development of gas turbine systems, particularly those constrained by emissions limitations. The existence and characteristics of dynamic instability are known to be functions of combustor geometry, flow conditions, and combustion parameters, but the form of dependence is not well understood. By modifying the acoustic boundary conditions, changes in flame and flow structure due to inlet parameters can be studied independent of the acoustic modes with which they couple. This paper examines the effect of equivalence ratio on the flame macrostructure — the relationship between the turbulent flame brush and the dominant flow structures — in an acoustically uncoupled environment. The flame brush is measured using CH* chemiluminescence, and the flow is interrogated using two-dimensional particle image velocimetry. We examine a range of equivalence ratios spanning three distinct macrostructures. The first macrostructure (ϕ = 0.550) is characterized by a diffuse flame brush confined to the interior of the inner recirculation zone. We observe a conical flame in the inner shear layer, continuing along the wall shear layer in the second macrostructure (ϕ = 0.600). The third macrostructure exhibits the same flame brush as the second, with an additional flame brush in the outer shear layer (ϕ = 0.650). Between the second and third macrostructures, we observe a regime in which the flame brush transitions intermittently between the two structures. We use dynamic mode decomposition on the PIV data to show that this transition event, which we call flickering, is linked to vorticity generated by the intermittent expansion of the outer recirculation zone as the flame jumps in and out of the outer shear layer. In a companion paper, we show how the macrostructures described in this paper are linked with dynamic instability [1].
Citation:
LaBry ZA, Taamallah S, Kewlani G, Shanbhogue SJ, Ghoniem AF (2014) Mode Transition and Intermittency in an Acoustically Uncoupled Lean Premixed Swirl-Stabilized Combustor. Volume 4B: Combustion, Fuels and Emissions. Available: http://dx.doi.org/10.1115/gt2014-27266.
Publisher:
ASME International
Journal:
Volume 4B: Combustion, Fuels and Emissions
KAUST Grant Number:
KUS-110-010-01
Issue Date:
16-Jun-2014
DOI:
10.1115/gt2014-27266
Type:
Conference Paper
Sponsors:
This research is funded by grant KUS-110-010-01 fromthe King Abdullah University of Science and Technology(KAUST) and grant R12-CE-10 from the King Fahd Universityof Petroleum and Mining (KFUPM).
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorLaBry, Zachary A.en
dc.contributor.authorTaamallah, Soufienen
dc.contributor.authorKewlani, Gauraven
dc.contributor.authorShanbhogue, Santosh J.en
dc.contributor.authorGhoniem, Ahmed F.en
dc.date.accessioned2016-02-25T13:42:22Zen
dc.date.available2016-02-25T13:42:22Zen
dc.date.issued2014-06-16en
dc.identifier.citationLaBry ZA, Taamallah S, Kewlani G, Shanbhogue SJ, Ghoniem AF (2014) Mode Transition and Intermittency in an Acoustically Uncoupled Lean Premixed Swirl-Stabilized Combustor. Volume 4B: Combustion, Fuels and Emissions. Available: http://dx.doi.org/10.1115/gt2014-27266.en
dc.identifier.doi10.1115/gt2014-27266en
dc.identifier.urihttp://hdl.handle.net/10754/598848en
dc.description.abstractThe prediction of dynamic instability remains an open and important issue in the development of gas turbine systems, particularly those constrained by emissions limitations. The existence and characteristics of dynamic instability are known to be functions of combustor geometry, flow conditions, and combustion parameters, but the form of dependence is not well understood. By modifying the acoustic boundary conditions, changes in flame and flow structure due to inlet parameters can be studied independent of the acoustic modes with which they couple. This paper examines the effect of equivalence ratio on the flame macrostructure — the relationship between the turbulent flame brush and the dominant flow structures — in an acoustically uncoupled environment. The flame brush is measured using CH* chemiluminescence, and the flow is interrogated using two-dimensional particle image velocimetry. We examine a range of equivalence ratios spanning three distinct macrostructures. The first macrostructure (ϕ = 0.550) is characterized by a diffuse flame brush confined to the interior of the inner recirculation zone. We observe a conical flame in the inner shear layer, continuing along the wall shear layer in the second macrostructure (ϕ = 0.600). The third macrostructure exhibits the same flame brush as the second, with an additional flame brush in the outer shear layer (ϕ = 0.650). Between the second and third macrostructures, we observe a regime in which the flame brush transitions intermittently between the two structures. We use dynamic mode decomposition on the PIV data to show that this transition event, which we call flickering, is linked to vorticity generated by the intermittent expansion of the outer recirculation zone as the flame jumps in and out of the outer shear layer. In a companion paper, we show how the macrostructures described in this paper are linked with dynamic instability [1].en
dc.description.sponsorshipThis research is funded by grant KUS-110-010-01 fromthe King Abdullah University of Science and Technology(KAUST) and grant R12-CE-10 from the King Fahd Universityof Petroleum and Mining (KFUPM).en
dc.publisherASME Internationalen
dc.titleMode Transition and Intermittency in an Acoustically Uncoupled Lean Premixed Swirl-Stabilized Combustoren
dc.typeConference Paperen
dc.identifier.journalVolume 4B: Combustion, Fuels and Emissionsen
dc.contributor.institutionMassachusetts Institute of Technology, Cambridge, MAen
kaust.grant.numberKUS-110-010-01en
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