Effect of maturity on soot volume fraction measurements using the AC-LII technique in a laminar coflow ethylene diffusion flame - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Proceedings of the Combustion Institute Année : 2022

Effect of maturity on soot volume fraction measurements using the AC-LII technique in a laminar coflow ethylene diffusion flame

Résumé

The auto-compensating laser-induced incandescence (AC-LII) technique has been frequently used to measure soot volume fraction (fv) in flames. AC-LII relies on an assumption about the spectral variation of soot absorption function E(m,λ) at the two detection wavelengths for soot temperature determination. It has been a common practice to assume a constant E(m,λ) based on the believe that LII measures mature soot only. Since soot maturity in flames is a continuous phenomenon from young to mature, it is unclear how soot maturity affects the AC-LII measured fv. In this study, a correction to the AC-LII measured fv with the conventional hypothesis of mature soot is proposed based on the soot maturity coefficient β and absorption function E(m,λ) in a laminar coflow ethylene diffusion flame. The application of this correction is first demonstrated for synthetic time-resolved LII signals based on the spatial distribution of soot properties in the ethylene diffusion flame predicted by the CoFlame code. A significant decrease of the simulated incandescence signals SLII and soot temperature Teff is observed when the maturity coefficient is increased from 0 for fully mature soot to 1.2 for highly immature soot. Then the proposed correction is applied to AC-LII measured fv in the same flame with the help of spatial distributions of β and ratio of spectrally-resolved E(m,λ) by multiwavelength line-of-sight attenuation and emission (MW-LOSA/EMI) measurements. The uncorrected AC-LII measured fv is in general significantly lower than that measured by MW-LOSA/EMI, which inherently considers soot maturity. The corrected AC-LII fv results are in good agreement, within the experimental error, with those measured by MW-LOSA/EMI. Therefore, the proposed methodology can quantify the effect of soot maturity on AC-LII measured fv and largely eliminate the difference in the measurements of fv by AC-LII and MW-LOSA/EMI.
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Dates et versions

hal-03916767 , version 1 (31-12-2022)

Identifiants

Citer

Felipe Escudero, Juan Cruz, Ignacio Verdugo, Nicolás Gutierrez, Fengshan Liu, et al.. Effect of maturity on soot volume fraction measurements using the AC-LII technique in a laminar coflow ethylene diffusion flame. Proceedings of the Combustion Institute, 2022, ⟨10.1016/j.proci.2022.10.013⟩. ⟨hal-03916767⟩
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