Transition Weber number between surfactant-laden drop bag breakup and shear breakup of secondary atomization

Fuel spray and atomization characteristics play an important role in the performance of internal combustion engines and many applications of industry. In drop aerobreakup, there are two main breakup modes: general bag breakup and shear breakup, which are induced by Rayleigh-Taylor instability and Kelvin-Helmholtz instability, respectively. Influence of surfactant on drop deformation and breakup is remarkable. So the transition condition of surfactant-laden drop between general bag breakup and shear breakup will be different from pure liquid. In this work, we investigate the influence of surfactant on drop breakup morphology in a continuous air jet stream, and find the physical mechanism of surfactant-laden drop atomization. Finally the predicted expression of transition Weber number is obtained.