  This study aims to build a theoretical model to describe the ignition process
of spherical spray flame laden with fuel droplets under overall fuel-lean
condition. Two characteristic fronts are introduced to reveal where the
evaporation starts and ends in the ignition process. The results demonstrate
that the flame has been strengthened with extra fuel droplet adding while the
minimum ignition energy (MIE) is decreased. The evolution of the two
evaporation fronts in the flame kernel and propagating branches has also be
revealed coupled with the evaporation zone length.
