Modeling the formation of contrails produced by H2 fuel emissions

Alternative aviation fuels represent a promising approach to reduce contrails climate effect. In the frame of Cirrus H2 project (DGAC funding), the influence of fuel composition on exhaust plumes emission, and therefore on contrails, is investigated using the 1D detailed microphysical code MoMiE (Modle Microphysique pour Effluents) developed at ONERA1,2.In its most recent version the code has been adapted to Sustainable Alternative Fuels (SAF)2. It includes heterogenous freezing with soot activation by sulfur and organic species, as well as homogeneous freezing of liquid droplets of hydrated sulfates and organics, accounting for the competition between both nucleation modes. Chemiionization, brownian coagulation of particles, ice sublimation and condensation are also represented. The code outputs the different aerosols distributions (size and number) of sulfates, organics, dry soot, activated soot, and ice particles, homogeneously and heterogeneously formed. It has also been completed by the implementation of the entrainment of ambient particles (background soot, sulfates and ice particles), which are expected to play a significant role in the case of SAF, as these fuels drastically reduce soot and sulfur emissions in comparison to classical fossile kerosene fuels.The work presented here aims at adapting the microphysics of contrail formation included in MoMiE to the case of hydrogen fuel emissions. In the case of a full hydrogen fuel composition, effluents are essentially composed of water vapor and the microphysical processes of the contrail formation are expected to mainly involve the background particles. Different simulations will be performed to explore the mechanisms of contrail formation in this particular case, and will be confronted to the cases of kerosene and SAF emissions. Advancement and results of this study will be presented and discussed during the conference.1Vancassel X. et al., Numerical simulation of aerosols in an aircraft wake using a 3D LES solver and a detailed microphysical model, International Journal of Sustainable Aviation, 20142Rojo C. et al., Impact of alternative jet fuels on aircraft-induced aerosols, Fuel, 2014