Imperial College London
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ProfessorAlexTaylor

Faculty of Engineering, Department of Mechanical Engineering

Professor
 
 
 
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Contact

 

+44 (0)20 7594 7042a.m.taylor

 
 
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Location

 

618City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@inproceedings{Karlis:2019:10.2514/6.2019-0675,
author = {Karlis, E and Hardalupas, I and Taylor, A and Rogerson, J and Sadasivuni, S and Stopper, U and Stöhr, M},
doi = {10.2514/6.2019-0675},
publisher = {Aerospace Research Central},
title = {Thermoacoustic phenomena in an industrial gas turbine combustor at two different mean pressures},
url = {http://dx.doi.org/10.2514/6.2019-0675},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - CPAPER
AB  - The current paper studies the thermoacoustically unstable combustion, under elevatedmean pressure, of a commercial swirl stabilized gas turbine burner fitted with optically accessible windows. The considered measurements include particle image velocimetry (PIV),OH∗chemiluminescence imaging, high speed broadband flame imaging and dynamic pressuresignals. We study cases A and B, wherein natural gas flames at mean pressures equal to 3 barand 6 bar delivered thermal loads equal to 335 kW and 685 kW respectively. The flow fielddemonstrated a typical vortex breakdown induced inner recirculation zone and a sudden stepexpansion induced outer recirculation zone. In case A, high amplitude dynamic pressure burstswere observed amidst a quiescent acoustic background. The flame was conical, it anchored onthe shear layers of the recirculation zone and it periodically expanded in the outer recirculation zone (ORZ). In case B, the flame was consistently thermoacoustically unstable with seldomrequiescent events, while at the same time expansion to the ORZ was suppressed. By applyingDynamic Mode Decomposition on high speed images of case A, it was showed that this expansionintroduced an additional time scale, further to the fundamental acoustically related timescale.The superposition of two timescales over a turbulent background established an intermittentregime of thermoacoustic instabilities, wherein the dynamics transitioned between quiescentand fully oscillatory. A physical mechanism is suggested to explain the differences betweenthe flame shapes on adjusting mean pressure. The mechanism considers that the premixtureis characterized by a Lewis number lower than unity, the laminar flame speed increases ondecreasing mean pressure and the flow imposed on the flame strain rate oscillated over a periodof thermoacoustic instability. This combination resulted in oscillatory heat release rate, in theregion of the outer shear layers. The phenomenon was more pronounced in case A than
AU  - Karlis,E
AU  - Hardalupas,I
AU  - Taylor,A
AU  - Rogerson,J
AU  - Sadasivuni,S
AU  - Stopper,U
AU  - Stöhr,M
DO  - 10.2514/6.2019-0675
PB  - Aerospace Research Central
PY  - 2019///
TI  - Thermoacoustic phenomena in an industrial gas turbine combustor at two different mean pressures
UR  - http://dx.doi.org/10.2514/6.2019-0675
UR  - https://arc.aiaa.org/doi/10.2514/6.2019-0675
UR  - http://hdl.handle.net/10044/1/66947
ER  -
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