The initial breakup of the spray jet plays a pivotal role in engine combustion performance (including ignition delay, heat release rate and combustion phase) and emissions [1]. The liquid fuel generally begins its breakup at the outlet of the injector tip and the primary breakup determines the spray initiation and evolution, for instance the spray morphology and macroscopic characteristics [1,2]. The spray morphology dominates momentum transfer between liquid and gas, thus the fuel distribution, mixture preparation and the resultant combustion performance and emissions [1,3]. Better primary breakup is thought to provide better dispersion quality and secondary dispersion, thus smaller droplets [2]. The smaller droplets are expected to evaporate and diffuse more quickly, thus forming combustible air/fuel mixture more quickly.