Influence of the ambient pressure on the liquid accumulation and on the primary spray in prefilming airblast atomization

•We derive a scaling of the SMD of the primary spray versus the ambient pressure.•We present an objective threshold to distinguish primary and secondary breakup.•We show that non-spherical droplets have a major impact on the drop size distribution.•We demonstrate the superiority of the aerodynamic stress over gas velocity or ambient pressure to characterize prefilming airblast atomization.