Large-Scale Coherent Structures as Drivers of Combustion Instability

Schadow, K. C.; Gutmark, Ephraim; Parr, T. P.; Parr, D. M.; Wilson, Kenneth; Crump, J. E.

doi:10.1080/00102208908924029

Cited by 144 publications

(27 citation statements)

References 17 publications

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“…Investigations of combustion instabilities in swirl flames are published e.g. in [5,12,21] and state the importance of coherent structures in the vicinity of the stabilization zone. The coherent structures represent a phenomenon that carefully has to be taken into account in modern burner development and, therefore, are a major topic in present investigations.…”

Section: Objectivementioning

confidence: 99%

Prediction of Pressure Oscillations in a Premixed Swirl Combustor Flow and Comparison to Measurements

Habisreuther

Bender

Petsch

et al. 2006

Flow Turbulence Combust

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The most common and reliable technique used for flame stabilization of industrial combustors with high thermal loads is the application of strongly swirling flows. In addition to stabilization, swirl flames offer the possibility to influence emission characteristics by simply changing the swirl intensity or the type of swirl generation. Despite of these major advantages, swirling flows tend to evolve flow instabilities, that considerably constitute a significant source of noise. In general, noise generation is substantially enhanced, when such a swirling flow is employed for flames. Thus, the minimization of the resulting noise emissions under conservation of the benefit of high ignition stability is one major design challenge for the development of modern swirl stabilized combustion devices. The present investigation makes an attempt to determine mechanisms and processes to influence the noise generation of flames with underlying swirling flows. Therefore, a new burner has been designed, that offers the possibility to vary geometrical parameters as well as the type of swirl generation, typically applied in industrial devices. Experimental data has been acquired for the isothermal flow as well as swirl flames by means of 3-D-LDV-diagnostics comprising the components of long-time averaged mean and rmsvelocities as well as spectrally resolved velocity fluctuations for all components. The noise emission data was acquired with microphone probes resulting in sound pressure levels outside the zone of the perceptible fluid flow. Along to the experiments, numerical simulations using RANS and LES have been carried out for isothermal cases with different burner outlet geometries. The results of the measurements show a distinct rise of the sound pressure level, obtained by changing both the test setup from the isothermal into the flame configuration as well as the geometrical parameters. This is also resembled by the LES simulation results. Furthermore, a physical model has been developed from experiments and verified by the LES simulation, that

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Section: Objectivementioning

confidence: 99%

Prediction of Pressure Oscillations in a Premixed Swirl Combustor Flow and Comparison to Measurements

Habisreuther

Bender

Petsch

et al. 2006

Flow Turbulence Combust

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“…(3) may break down at high Reynolds numbers [51]. Other techniques for measuring the heat release rate include Planar Laser Induced Florescence (PLIF), which uses a laser to excite particular species and images the resultant emissions with an intensified camera [52], Flame Surface Density (FSD) calculated from OH PLIF [31] and Reaction Rate (RX) imaging from simultaneous OH and CH 2 O PLIF measurements [31]. Balachandran et al [31] found good correlation between several different techniques, including RX, FSD, and OH * and CH * chemiluminescence.…”

Section: Measurement Techniquesmentioning

confidence: 99%

Thermoacoustic limit cycles in a premixed laboratory combustor with open and choked exits

Hield

Brear

Jin

2009

Combustion and Flame

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“…Some of the mechanisms which have been identified as potentially significant are flame area fluctuations driven by acoustic velocity perturbations [1,2] and/or large-scale, convected coherent structures [3,4], unsteady flame extinction and reignition, flame-wall interactions [5], and reactive normal direction to flame front toward a burned gas uni uniform perturbation cv convected perturbation mixture composition perturbations (i.e., equivalence ratio oscillations) [6][7][8][9][10]. The latter mechanism, equivalence ratio oscillations excited by pressure and/or velocity oscillations in the premixer, is known to be particularly important in lean, premixed combustors.…”

Section: Introductionmentioning

confidence: 99%