Sustainable Aviation Fuel: controlling Flame Dynamics and reducing emissions – SAFARI

Sustainable Aviation Fuels (SAF), encompassing fuels synthesized from biomass (biofuels) or zero-carbon electrical sources (electrofuels), offer a short-term solution for decarbonizing the aeronautical sector. Exhibiting main properties similar to conventional jet fuel, using SAF does not require completely redesigning current combustion chambers. However, given the diverse feedstock required to meet energy demands, SAF compositions may vary considerably. Recent studies indicate that these variations affect combustion chamber performance, influencing operability and emissions. Aeronautical engineers are also faced with the challenge of burning SAF under lean combustion regimes to minimize the production of pollutants. However, lean combustion can promote flame blowout and instability, requiring effective solutions for enhancing flame stabilization.
The SAFARI project aims to gain fundamental insights into SAF combustion's multi-physic phenomena and develop numerical tools for designing future combustion chambers. In particular, the main objectives are: i) to understand the effects of pressure, heat transfer, and fuel composition variability on flame dynamics and pollutant emissions, such as NOx and soot particles, ii) to generate a detailed experimental database to validate turbulent combustion models, iii) develop and validate an advanced CFD modeling strategy, iv) test the relevance of plasma-assisted combustion for improving flame stabilization and preventing combustion instabilities in lean regimes.
To achieve these objectives, the project is structured into three phases. Firstly, fundamental experimental diagnostics and advanced numerical tools will be developed to measure and model the chemical flame structure and its interactions with turbulence and heat transfer in a high-pressure and two-phase flow environment. Mixtures of chemical species will be identified to dissociate the influence of composition variability on flame chemical processes from differential evaporation processes. Secondly, these experimental and numerical tools will address fundamental physical questions concerning SAF combustion operability in terms of stabilization, dynamics, and pollutant formation. A series of reactive experimental configurations of increasing complexity in operating pressure and injection systems will be introduced to address each scientific question separately. The relevance of plasma-assisted combustion for stabilizing and preventing instabilities in lean two-phase flames will be assessed.
The project will conclude with four applicative challenges identified to characterize, under real aero-engine conditions, 1) the behavior of high-pressure flames, 2) pollutant emissions, 3) chamber operability, and 4) combustion control by plasma-assisted combustion, respectively.