Work

Influence of H2 addition on emission characteristics of SAF/Jet A1 blend in a low-swirl combustor

Year: 2026

Type: article

Abstract: Aviation kerosene is the primary fuel for modern aviation turbine engines. The aviation sector contributes roughly 2.4% of global CO₂ emissions and, in response, alternative fuels have been actively explored. Sustainable Aviation Fuels (SAFs), typically derived from biomasses and other renewable feedstocks, have attracted considerable attention. Under current regulations, SAFs can be blended with conventional kerosene up to 50% by volume. Moreover, SAF can reduce life‐cycle greenhouse‐gas emissions by up to ∼89% respect to conventional kerosene. Hydrogen (H 2 ) represents another promising alternative, as it burns without carbon emissions and has a higher mass-based energy content compared to hydrocarbon fuels. Blending SAF (or conventional jet fuel) with H 2 is being considered as a transitional pathway towards a more sustainable aviation. However, successful adoption of such blends requires a detailed understanding of their combustion characteristics. In this study, we investigate the flame stabilization and pollutant emissions in an innovative fuel‐flexible combustor operating with Jet A1, HEFA-SAF (i.e., SAF produced from Hydroprocessed Esters and Fatty Acids), and H 2 at atmospheric pressure and elevated air inlet temperatures. Significant attention is directed toward particulate (soot) emissions from the flames fuelled with HEFA-SAF/Jet A1 blends, both with and without H 2 . The results reveal significant differences: small additions of H 2 can transiently increase the formation of early particulate precursors, whereas higher H₂ blends strongly suppress particulate nucleation and growth. Flames with high H 2 content achieved near‐zero soot emissions and lower CO emissions, demonstrating the potential of H 2 and blended SAF/Jet A1 combustion for clean aviation propulsion. Novelty and significance statement The current study investigates the spatially resolved characterization of soot particle formation in an innovative fuel-flexible burner. The burner integrates a lean-lifted spray SAF/Jet A1 flame with hydrogen (H 2 ) injectors arranged around the prefilmer. The results demonstrate significant trends: even small H 2 additions can transiently enhance the formation of early soot precursors, while higher H 2 fractions strongly suppress soot nucleation and growth. Overall, the system maintains very low particulate emissions across the investigated conditions. These experiments provide new insights into the drop-in compatibility of dual-fuel systems, offering a viable pathway to decarbonize aviation combustion systems.

Source: Proceedings of the Combustion Institute

DOI: 10.1016/j.proci.2026.106648