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Modeling and simulation of soot production in aeronautical engine conditions

ED MEGEP

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The certification of aeronautical engines to increasingly stringent soot emission standards require predictive models capable of handling complex industrial configurations at a reasonable computational cost. This thesis proposes an advanced soot simulation methodology by integrating Analytically Reduced Chemistry (ARC) with a detailed description of polycyclic aromatic hydrocarbons (PAHs) and the Lagrangian Soot Tracking (LST) model within the AVBP code.

The methodology is first validated on laminar flames from the International Sooting Flame (ISF) workshop, showing strong agreement with experimental measurements in terms of species and soot predictions. A detailed study on the Gülder laminar flame highlights the improved description of soot morphology with a new surface model based on aggregates, although discrepancies remain in soot volume fraction. Additionally, a soot maturity model is introduced to track the hydrogen-to- carbon ratio, a proxy for soot chemical composition.

To mitigate the computational cost associated with PAH inclusion, a hybrid model called PAHARC is developed. This model combines a compact reduced scheme for flame resolution with a tabulation approach for PAH access. The approach is applied to turbulent configurations, including the Cambridge burner and the 4SI aeronautical combustion chamber. Simulations show that the PAHARC model significantly reduces computational cost while maintaining satisfactory predictions. In the Cambridge burner, results indicate that LST overestimates the size of soot aggregates, although the particle size distribution remains consistent with experimental trends. Finally, soot modeling in the 4SI provides valuable insights into soot formation and evolution, despite the lack of experimental data for comparison.

In conclusion, this thesis establishes a robust framework for soot modeling in flames, with strong potential for turbulent cases. The proposed advancements pave the way for more accurate and cost-effective soot population predictions in AVBP, addressing certification challenges and emission reduction objectives.

Jury

M. Jean-Christophe JOUHAUD	CERFACS	PhD supervisor
M. Jeroen VAN OIJEN	CORIA, Rouen	Reviewer
Mme Benedetta FRANZELLI	EM2C, Paris	Reviewer
M. Jérôme YON	INSA, Rouen	Examiner
M. Epaminondas MASTORAKOS	Cambridge UK	Examiner
Mme Bénédicte CUENOT	Safran Aircraft Engine	Invited member
Mme Eléonore RIBER	CERFACS	Invited member