SOOT PRECURSORS ANALYSIS USING DETAILED CHEMICAL KINETIC MECHANISMS IN AN ETHYLENE/AIR LAMINAR DIFFUSION FLAME

Sebastián Ruiz (1) , Cesar Celis (1) , Luis Fernando Figueira da Silva (2, 3)

1 PUCP - Pontificia Universidad Católica del Perú = Pontifical Catholic University of Peru
2 PUC-Rio - Pontifícia Universidade Católica do Rio de Janeiro [Brasil] = Pontifical Catholic University of Rio de Janeiro [Brazil] = Université catholique pontificale de Rio de Janeiro [Brésil]
3 PPrime [Poitiers] - Institut Pprime [UPR 3346]

Tens or even hundreds of chemical species are produced in the nascent stages of hydrocarbon-based fuels combustion that eventually lead to the formation of soot particles and aggregates. In such context, the study of sootrelated chemical species formation and its associated physical-chemical phenomena are of great importance to delve into how in combustion processes the formation of this critical pollutant is carried out. In this work thus, accounting for an ethylene/air laminar diffusion flame previously experimentally characterized employing a Gülder burner configuration, both soot precursors and soot formation are analyzed. Computational mesh independence is addressed here by refining grid elements in such a way that element sizes in the reaction zone are of about 30µm, thus capturing species and temperature gradients in such regions. The NBP (Narayanaswamy, Blanquart and Pitsch Stanford University mech) chemical kinetic mechanism featuring 149 chemical species and 1651 reactions is used for describing gas phase chemistry. Radiation effects are addressed using the discrete ordinates method (DOM) and computing the associated absorption coefficient from a WSGG model. Two soot formation models, an acetylene-based semiempirical and a statistical PAH-based method of moments (MOM), are employed in the soot-related numerical simulations carried out. Temperature profiles predicted using the MOM soot formation model are in fair agreement with the experimental results (peak temperature discrepancies of about 3%). Along the flame centerline and near the burner surface, predicted soot volume fractions match as well the corresponding experimental trends. In the radial direction however, both models lack of precision for describing the soot peak values and their physical location. From the species molar fractions results discussed here, it is observed that one and two aromatic ring groups are the most abundant PAH, so these PAH might be sufficient for soot nucleation purposes. The numerical models and methodologies developed in this work will be used in future for predicting soot formation in turbulent diffusion flames.

Mots clés: Soot precursors; Detailed kinetic mechanisms; PAH; Soot modeling; Laminar diffusion flames

Domaines: Milieux fluides et réactifs

Sebastián Ruiz, Cesar Celis, Luis Fernando Figueira da Silva. SOOT PRECURSORS ANALYSIS USING DETAILED CHEMICAL KINETIC MECHANISMS IN AN ETHYLENE/AIR LAMINAR DIFFUSION FLAME. 26th International Congress of Mechanical Engineering, Nov 2021, Florianopolis, Brazil. ⟨10.26678/ABCM.COBEM2021.COB2021-0061⟩. ⟨hal-03357858⟩