Investigation on reaction mechanism simplification and hydrogen-blended combustion characteristics for a hydro-processed bio-jet fuel

Amidst the urgent global need for deep decarbonization in aviation, the development of sustainable aviation fuels (SAFs) and compatible low-emission combustion technologies is a key research priority. Blending hydrogen (H₂) with SAFs such as hydro-processed esters and fatty acids synthetic paraffinic kerosene (HEFA-SPK) is considered a technologically viable pathway to reduce combustion-phase carbon emissions. In this study, the reaction kinetic mechanism for a representative HEFA-SPK fuel (ZH-HEFA) was systematically simplified and validated using Chemkin-Pro. The combustion characteristics of hydrogen-blended HEFA were further investigated via computational fluid dynamics (CFD) in ANSYS Fluent. In a zero-dimensional homogeneous reactor, a detailed mechanism comprising 3032 species and 10583 reactions was simplified to 599 species and 2789 reactions, achieving a reduction of over 80% (by species). The simplified mechanism was validated by comparing key species concentrations (H₂, O₂, CO, CO₂, H₂O) in a plug-flow reactor, ignition delay times in a zero-dimensional homogeneous reactor, and the laminar flame speeds of HEFA and HEFA/H₂ blends in a laminar premixed flame reactor. Furthermore, by integrating the technical advantages of LDI and LPP concepts, a low-emission combustor suitable for hydrogen-blended HEFA was designed, which maintains combustion performance while remaining compatible with the nozzle structures of existing aero-engines. Steady-state and transient combustion characteristics of hydrogen-blended HEFA were investigated, focusing on the flow field, temperature field, and pollutant emissions to elucidate key combustion-phase properties.