Stochastic ignition of fuel droplets impacting a hot surface: comparison of alkanes, conventional, and sustainable aviation fuels*

Flammable fluids dripping onto hot surfaces are a major source of fires in aircraft, vehicles, and heavy machinery. The present work investigates experimentally the ignitability of different liquid fuels (linear alkanes, conventional petroleum-derived aviation fuels, and sustainable aviation fuels synthetized from biomass feedstocks) in an idealized scenario in which mm-sized fuel droplets orthogonally impact a flat surface raised to temperatures well-above the Leidenfrost point, in quiescent atmospheric pressure air. These droplets, with Weber number in the order of 250, break up on impact and ignite if the surface temperature is sufficiently elevated. We performed high speed imaging of the droplet break-up and combustion process, and report ignition probabilities and time-to-ignition for the different fuels. In addition, the composition of the fuels was characterized. Evaporation and combustion properties were derived from simulations to interpret our experimental results.