Effects of inert fuel diluents on thermoacoustic instabilities in gas turbine combustion
File(s)
Accepted version
Author(s)
Karlis, E
Hardalupas, Y
Taylor, AMKP
Type
Journal Article
Abstract
The effects of inert diluents in the fuel mixture of a model swirl stabilized gas turbine combustor, under thermoacoustically unstable limit cycle operation, were studied experimentally. The measurements included particle image velocimetry (PIV), high-speed CH* chemiluminescent imaging, and dynamic pressure signals. The paper focuses on the dynamic phenomenon of the period doubling bifurcation, which came about when the equivalence ratio ϕ of undiluted flames was enriched from 0.55 to 0.60 under constant Reynolds number (Re=18,000). The bifurcation featured an emergence of an aerodynamically related timescale in addition to the fundamental timescale that was induced from an unstable acoustic eigenmode. The aerodynamic timescale is introduced by azimuthal convection of a high-heat-release-rate region and is linked in the literature with a precessing motion of the recirculation zone. It was found that on increasing the diluent molar fraction up to 50%, the amplitude and the frequency of the limit cycle fundamental acoustic mode decreased. A mechanism to interpret this suppression is that increasing the diluent molar fraction of the fuel makes the flame more susceptible to quenching because the extinction strain rate of the mixture is decreased. The paper argues that the existence of inert diluents in the fuel can significantly alter the dynamic state of the combustor, because the anchoring locations of the flame greatly depend on the composition-sensitive extinction strain rate of the mixture.
Date Issued
2020-04-20
Date Acceptance
2020-02-20
Citation
AIAA Journal: devoted to aerospace research and development, 2020, 58 (6), pp.2643-2657
ISSN
0001-1452
Publisher
American Institute of Aeronautics and Astronautics
Start Page
2643
End Page
2657
Journal / Book Title
AIAA Journal: devoted to aerospace research and development
Volume
58
Issue
6
Copyright Statement
© 2020 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. All requests for copying and permission to reprint should be submitted to CCC at www.copyright.com; employ the eISSN 1533-385X to initiate your request. See also AIAA Rights and Permissions www.aiaa.org/randp.
Sponsor
Engineering & Physical Science Research Council (E
Engineering & Physical Science Research Council (EPSRC)
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000537952100025&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
J13878
EP/M015300/1
Subjects
Science & Technology
Technology
Engineering, Aerospace
Engineering
HEAT RELEASE FLUCTUATIONS
COHERENT STRUCTURES
EQUIVALENCE RATIO
SWIRLING JET
FLAME
OSCILLATIONS
EXTINCTION
MECHANISMS
STABILITY
DILUTION
Publication Status
Published
Date Publish Online
2020-04-20