Temporally resolved planar measurements of transient phenomena in a partially pre-mixed swirl flame in a gas turbine model combustor

Journal Article · Sun Aug 15 00:00:00 EDT 2010 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2009.12.015· OSTI ID:21331454

Boxx, I; Stoehr, M; Meier, W ^[1]; Carter, C ^[2]

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1. Institut fuer Verbrennungstechnik, Deutsches Zentrum fuer Luft-und Raumfahrt (DLR), Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany)
2. Air Force Research Laboratory (AFRL)/PRAS, 1950 Fifth St, Wright-Patterson AFB, OH (United States)

This paper presents observations and analysis of the time-dependent behavior of a 10 kW partially pre-mixed, swirl-stabilized methane-air flame exhibiting self-excited thermo-acoustic oscillations. This analysis is based on a series of measurements wherein particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) of the OH radical were performed simultaneously at 5 kHz repetition rate over durations of 0.8 s. Chemiluminescence imaging of the OH{sup *} radical was performed separately, also at 5 kHz over 0.8 s acquisition runs. These measurements were of sufficient sampling frequency and duration to extract usable spatial and temporal frequency information on the medium to large-scale flow-field and heat-release characteristics of the flame. This analysis is used to more fully characterize the interaction between the self-excited thermo-acoustic oscillations and the dominant flow-field structure of this flame, a precessing vortex core (PVC) present in the inner recirculation zone. Interpretation of individual measurement sequences yielded insight into various physical phenomena and the underlying mechanisms driving flame dynamics. It is observed for this flame that location of the reaction zone tracks large-scale fluctuations in axial velocity and also conforms to the passage of large-scale vortical structures through the flow-field. Local extinction of the reaction zone in regions of persistently high principal compressive strain is observed. Such extinctions, however, are seen to be self healing and thus do not induce blowout. Indications of auto-ignition in regions of unburned gas near the exit are also observed. Probable auto-ignition events are frequently observed coincident with the centers of large-scale vortical structures, suggesting the phenomenon is linked to the enhanced mixing and longer residence times associated with fluid at the core of the PVC as it moves through the flame. (author)

• OSTI ID: 21331454
• Journal Information: Combustion and Flame, Vol. 157, Issue 8; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GAS TURBINES
POWER RANGE 01-10 KW
FLAMES
AIR
HYDROXYL RADICALS
AUTOIGNITION
CHEMILUMINESCENCE
METHANE
COMBUSTION KINETICS
TIME DEPENDENCE
FLUCTUATIONS
HEAT
OSCILLATIONS
COMBUSTORS
TRANSIENTS
VORTICES
MIXING
STRAINS
VELOCITY
Swirl flames
Turbulent flames
Precessing vortex core
Local extinction
Gas turbine model combustor