Comprehensive characterization of sooting butane jet flames, Part 1: Soot, soot-precursor, and reaction zone

Mulla, IA and Desgroux, P and Lecordier, B and Cessou, A (2021) Comprehensive characterization of sooting butane jet flames, Part 1: Soot, soot-precursor, and reaction zone. In: Combustion and Flame .

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Abstract

The present work examines the effect of Reynolds number (Re) on n-butane jet flames, ranging from laminar to turbulent regime (Re=2100 to 21,500). n-butane is chosen since it can represent the oxidation of larger paraffins contained in practical fuels. Several quantities are measured, and various data analysis approaches are employed. Soot volume fraction (fv) was measured using a laser-induced incandescence technique, whereas polycyclic aromatic hydrocarbons (PAH) and reaction zone (OH) were imaged using laser-induced fluorescence (LIF) tool. The mean and instantaneous images of OH, PAH, and soot volume fraction are examined. The reaction zone is the least affected by the turbulence, while the PAH-LIF signal is moderately affected. A strong effect of turbulence is observed on the soot concentration and intermittency. Soot and PAH concentration decreased with Re due to reduced residence time, increased strain rate, and likely increase in a scalar dissipation rate. In the turbulent regime, fv decreases with PAH at a sharper rate, possibly due to reduced local time scales associated with turbulent eddies. Soot structure complexity is quantified through a fractal dimension (Df). Df increased with Re; however, in a turbulent regime Df becomes insensitive to Re. A semi-global correlation between fv and sheet thickness is also analyzed. A power-law trend is noted in the fv vs. thickness plot. Coefficients of power-fit are found to be Re-dependent. Additionally, the local correlation between fv and sheet thickness is examined, which revealed a non-monotonic trend. fv peaks at a preferred soot sheet thickness. These analysis-derived insights can contribute towards the understanding of soot-turbulence interaction. Furthermore, the reported database will facilitate the validation of soot chemistry models intended for practical fuels. © 2021 The Combustion Institute

Item Type:	Journal Article
Publication:	Combustion and Flame
Publisher:	Elsevier Inc.
Additional Information:	The copyright for this article belongs to Elsevier Inc.
Keywords:	Butane; Combustion; Fractal dimension; Higher order statistics; Polycyclic aromatic hydrocarbons; Reynolds number; Strain rate; Turbulence; Volume fraction, Jet flames; n-Butane; OH+-; Polycyclic aromatics; Practical fuels; Reaction zones; Sheet thickness; Soot volume fraction; Turbulent regime; Turbulent sooting flame, Soot
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	28 Nov 2021 09:15
Last Modified:	28 Nov 2021 09:15
URI:	http://eprints.iisc.ac.in/id/eprint/69982

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