Date of Completion

Spring 4-26-2024

Thesis Advisor(s)

Francesco Carbone

Honors Major

Mechanical Engineering

Disciplines

Heat Transfer, Combustion | Optics

Abstract

Sustainable Aviation Fuels (SAFs) are seen as the path forward for decarbonizing hard-to-electrify sectors. Using SAFs over traditional fossil fuels abates carbon dioxide emissions but still may present soot emission problems. A milestone in the abatement of soot would be understating its formation mechanisms.

This study aims to quantify soot products resulting from an ethylene flame doped with iso-dodecane, a surrogate SAF component. The burner selected for the investigation is the novel Planar Mixing Layer Flame (PMLF) which allows the tracking of soot formation with the height above the burner (HAB) in a stable diffusion flame. A baseline ethylene-fueled flame and a seeded flame where 1500 ppmv of ethylene is replaced with iso-dodecane are studied. Both flames have the same carbon flux in the reactants, stoichiometric mixture fraction, and are studied at HAB = 50 mm and HAB = 25 mm to track soot growth. Laser Induced Incandescence (LII) and Elastic Laser Light Scattering (E-LLS) are used to measure soot volume fraction and scattering coefficient respectively, and the light scattering equivalent soot diameter is calculated from a combination of the techniques.

When iso-dodecane is seeded into the flame, the soot volume fraction increases by 50% compared to the baseline case at both HAB and across all horizontal positions in the sooting region. The scattering equivalent diameter of the soot nanoparticles is 2-3 times larger in the doped flame at HAB = 50 mm when compared to the baseline. Overall, this work demonstrates that SAF combustion results in exacerbated soot impact.

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