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Numerical simulation of an aeronautical hydrogen-air burner

MEGEP (Mécanique, Energétique, Génie civil & Procédés) – [Subject to defense authorization]

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To decarbonize aviation and move away from fossil fuels such as kerosene, which is mainly used in aeronautics, hydrogen, which does not emit carbonated products during its combustion, is a possible alternative. However, the transition to hydrogen aeronautical combustion chambers must be made quickly and within a relatively short timeframe compared to the development time of kerosene-operated chambers. To meet this need for rapid design and development, Computational Fluid Dynamics (CFD) can be a powerful tool to explore given burner geometries and different operating points at a reduced cost, in comparison to bench tests. However, in aeronautical engines it is necessary to maximize pressure and temperature for optimal efficiency (Joule-Brayton cycle). This observation is not without consequences for the development phases; indeed, pressure (P) and temperature drastically influence flame thicknesses, which evolve as 1/P. Thus, at high pressure, the flame front can be hardly resolved on a mesh, which requires the use of models and therefore limits the accuracy of the results. The goal of this thesis is to provide a numerical methodology to identify combustion key phenomena occurring in aeronautical combustion chambers at high pressure. To do so, different elementary configurations are studied in Direct Numerical Simulation (DNS) (absence of models) 1D, 2D, and 3D. The stabilization of the flame on the injector lips is addressed, as well as the phenomena of blow-off and flame flashback. A study is then conducted at 4 bar in Large Eddy Simulation (LES) (using models) on the MICADO test bench with the PHYDROGENE injector, comparing and validating the code (AVBP) against the experimental results. Finally, a simplified version of the injector is used in an exploratory phase of operation at a higher pressure (12 bar).

Jury

James DAWSON	NTNU	Reviewer
Ronan VICQUELIN	EM2C	Reviewer
Thierry SCHULLER	IMFT	Examiner
Karine TRUFFIN	IFP Energies nouvelles	Examiner
Thierry POINSOT	Cerfacs	Thesis supervisor
Stéphane RICHARD	Safran Helicopter Engines	Invited member
Nicolas BERTIER	ONERA	Thesis co-supervisor