Time-resolved spatial patterns and interactions of soot, PAH and OH in a turbulent diffusion flame

Franzelli, Benedetta; Scouflaire, Philippe; Candel, Sébastien

doi:10.1016/j.proci.2014.06.123

Cited by 31 publications

(39 citation statements)

References 21 publications

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“…Soot volume fraction appears in the form of layers of approximately 0.5-2.5 mm thickness, which are clearly distinguishable and comparable to previous 1 The immediate vicinity of the wall is not accessible due to the limitation of the optical access, reducing the field of view by about 5 mm for each side. experiments [4,6]. A close-up view of these ligaments is presented for two HABs in Fig.…”

Section: Soot Structurementioning

confidence: 99%

“…In addition to the many studies carried out on sooting laminar flames, it is worth examining soot production in turbulent flows that are widely used in industrial applications. In this respect, much of the technical literature has focused on soot in turbulent jet diffusion flames [4][5][6][7][8]. This case has been extensively investigated with a variety of diagnostics, highlighting the effects of turbulent eddies, strain rate and scalar dissipation on the soot volume fraction f v distribution.…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of soot production in a confined swirled flame operating under perfectly premixed rich conditions

Roussillo

Scouflaire

Candel

et al. 2019

Proceedings of the Combustion Institute

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A detailed understanding of the mechanisms underlying soot production is needed to control particle emissions from practical combustion devices. This requires fundamental investigations of these processes in turbulent combustion systems. This study reports experiments on soot production in a perfectly premixed turbulent flame operating under rich conditions. A swirled ethylene/air flame is stabilized in a confined combustor at atmospheric pressure with full optical access. Quantitative measurements of the soot volume fraction ( f v ) are carried out with the Laser Induced Incandescence (LII) technique, allowing the characterization of the soot spatial distribution and temporal intermittency. While f v is detected by LII mainly in the near-wall region of the burner, light scattering measurements bring complementary information on the presence of particles in the whole chamber. The investigation of a rich perfectly premixed turbulent flame represents an unexplored configuration that provides new insights on soot production in a situation where this process is not dominated by mixing between fuel and air. The data gathered in this situation may be of interest in future developments of modeling methods and their validation for soot prediction.

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Section: Soot Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental investigation of soot production in a confined swirled flame operating under perfectly premixed rich conditions

Roussillo

Scouflaire

Candel

et al. 2019

Proceedings of the Combustion Institute

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“…Although laminar flame (e.g., Karataş & Gülder 2012) and turbulent flame (e.g., Coppalle & Joyeux 1994, Kent & Honnery 1987) experiments had been conducted in the past, the tremendous advancement of laser diagnostics has allowed much more detailed measurements recently (e.g., Desgroux et al 2013, Franzelli et al 2015, Mahmoud et al 2015, Narayanaswamy & Clemens 2013, Zhang et al 2011. Of particular interest are simultaneous measurements, in which two or more flow quantities are measured to provide joint statistics.…”

Section: Sooting Flamesmentioning

confidence: 99%

“…Of particular interest are simultaneous measurements, in which two or more flow quantities are measured to provide joint statistics. Examples include the velocity-soot volume fraction (Narayanaswamy & Clemens 2013), velocity-OH (Geigle et al 2013, PAH-OH (Franzelli et al 2015), and temperature-soot volume fraction (Chan et al 2011). Apart from the macroscopic comparison of soot or composition fields, quantitative simultaneous measurements allow specific assumptions about the turbulence and its influence on chemistry to be validated.…”

Section: Sooting Flamesmentioning

confidence: 99%

Modeling of Fine-Particle Formation in Turbulent Flames

Raman

Fox

2016

Annu. Rev. Fluid Mech.

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The generation of nanostructured particles in high-temperature flames is important both for the control of emissions from combustion devices and for the synthesis of high-value chemicals for a variety of applications. The physiochemical processes that lead to the production of fine particles in turbulent flames are highly sensitive to the flow physics and, in particular, the history of thermochemical compositions and turbulent features they encounter. Consequently, it is possible to change the characteristic size, structure, composition, and yield of the fine particles by altering the flow configuration. This review describes the complex multiscale interactions among turbulent fluid flow, gas-phase chemical reactions, and solid-phase particle evolution. The focus is on modeling the generation of soot particles, an unwanted pollutant from automobile and aircraft engines, as well as metal oxides, a class of high-value chemicals sought for specialized applications, including emissions control. Issues arising due to the numerical methods used to approximate the particle number density function, the modeling of turbulence-chemistry interactions, and model validation are also discussed. 159

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“…This requires time-resolved LII measurements, where the temporal evolution of the soot structures can be tracked. Franzelli et al recently reported 10 kHz measurements of soot structures with soot scattering simultaneous with polycyclic aromatic hydrocarbon (PAH) and OH fluorescence, but they did not address in detail the potential for quantitative soot volume fraction measurements [30]. There are relatively few reports of high-repetition rate LII studies in which the effects of repetitive pulsing on soot physical characteristics have been evaluated.…”

Section: Introductionmentioning

confidence: 99%

Effects of repetitive pulsing on multi-kHz planar laser-induced incandescence imaging in laminar and turbulent flames

et al. 2015

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Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burstmode laser system to enable studies of soot formation dynamics in highly turbulent flames. To quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals are observed at measurement rates up to 100 kHz but are primarily useful for qualitative tracking of soot structure dynamics. However, LII signals collected at lower fluences allow sequential planar measurements of the relative soot volume fraction with a sufficient signal-to-noise ratio at repetition rates of 10-50 kHz. Guidelines for identifying and avoiding the onset of repetitive probe effects in the LII signals are discussed, along with other potential sources of measurement error and uncertainty. RightsThis paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: https://www.osapublishing.org/ ol/abstract.cfm?uri=ol-40-9-2029&origin=search. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law. Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. To quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals are observed at measurement rates up to 100 kHz but are primarily useful for qualitative tracking of soot structure dynamics. However, LII signals collected at lower fluences allow sequential planar measurements of the relative soot volume fraction with a sufficient signal-to-noise ratio at repetition rates of 10-50 kHz. Guidelines for identifying and avoiding the onset of repetitive probe effects in the LII signals are discussed, along with other potential sources of measurement error and uncertainty.

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Time-resolved spatial patterns and interactions of soot, PAH and OH in a turbulent diffusion flame

Cited by 31 publications

References 21 publications

Experimental investigation of soot production in a confined swirled flame operating under perfectly premixed rich conditions

Experimental investigation of soot production in a confined swirled flame operating under perfectly premixed rich conditions

Modeling of Fine-Particle Formation in Turbulent Flames

Effects of repetitive pulsing on multi-kHz planar laser-induced incandescence imaging in laminar and turbulent flames

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