Detailed characterization of the dynamics of thermoacoustic pulsations in a lean premixed swirl flame

Journal Article · Sun Jul 15 00:00:00 EDT 2007 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2007.04.002· OSTI ID:20919408

Meier, W; Weigand, P; Duan, X R; Giezendanner-Thoben, R ^[1]

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1. Institut fuer Verbrennungstechnik, Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Pfaffenwaldring 38, D-70569 Stuttgart (Germany)

A nozzle configuration for technically premixed gas turbine flames was operated with CH{sub 4} and air at atmospheric pressure. The flames were confined by a combustion chamber with large quartz windows, allowing the application of optical and laser diagnostics. In a distinct range of operating conditions the flames exhibited strong self-excited thermoacoustic pulsations at a frequency around 290 Hz. A flame with P=25kW thermal power and an equivalence ratio of {phi}=0.7 was chosen as a target flame in order to analyze the dynamics and the feedback mechanism of the periodic instability in detail. The velocity field was measured by three-component laser Doppler velocimetry, the flame structures were measured by chemiluminescence imaging and planar laser-induced fluorescence of OH, and the joint probability density functions of major species concentrations, mixture fraction, and temperature were measured by laser Raman scattering. All measuring techniques were applied in a phase-locked mode with respect to the phase angle of the periodic pulsation. In addition to the pulsating flame, a nonpulsating flame with increased fuel flow rate (P=30kW, {phi}=0.83) was studied for comparison. The measurements revealed significant differences between the structures of the pulsating and the nonpulsating (or ''quiet'') flame. Effects of finite-rate chemistry and unmixedness were observed in both flames but were more pronounced in the pulsating flame. The phase-locked measurements revealed large variations of all measured quantities during an oscillation cycle. This yielded a clear picture of the sequence of events and allowed the feedback mechanism of the instability to be identified and described quantitatively. The data set presents a very good basis for the verification of numerical combustion simulations because the boundary conditions of the experiment were well-defined and the most important quantities were measured with a high accuracy. (author)

• OSTI ID: 20919408
• Journal Information: Combustion and Flame, Vol. 150, Issue 1-2; 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
42 ENGINEERING
GAS TURBINES
FLAMES
COMBUSTION
METHANE
PERIODICITY
PULSATIONS
AIR
PROBABILITY DENSITY FUNCTIONS
FEEDBACK
INSTABILITY
MIXTURES
HZ RANGE
OSCILLATIONS
VALIDATION
ATMOSPHERIC PRESSURE
BOUNDARY CONDITIONS
COMBUSTION CHAMBERS
FLOW RATE
ACCURACY
VARIATIONS
NOZZLES
VELOCITY
TEMPERATURE DISTRIBUTION
ABUNDANCE
POWER RANGE 10-100 KW
COMBUSTION KINETICS