  Traditionally, circular orifices have been used for generating aerosols,
however in recent times non-circular orifices are being considered due to their
superior atomization and mixing features. In this work, we experimentally
investigate spray morphology and drop size characteristics of kerosene (Jet
A-1) jets issuing from three non-circular orifices geometries (elliptic,
triangular and, square) and one circular orifice with the same exit cross
sectional area. Our results show an unexpected and yet unreported coarsening of
atomization for non-circular orifice jets quantified by an increase in the
Sauter Mean Diameter (SMD) at all tested exit velocities represented by the
liquid Weber number, $We_l$. We attribute this to two distinct spray
morphologies: filament and core breakup which generate large size liquid
structures identified as filaments and ligaments, noticeable in non-circular
orifices jets compared to circular orifice jets. On exploring this further by
undertaking an examination of the drop size volume probability distribution at
lower $We_l$ corresponding to the location marking the end of primary breakup
we see a bimodality due to a dominant distribution of fragments of small and
larger sizes owing to the spray morphology. At higher $We_l$ and larger
distances from the injector exit we observe the bimodality converts to a
unimodal distribution for all orifice jets with a single peak situated at lower
drop diameters. Filament breakup is reasoned to be the cause of higher number
of smaller drop sizes in triangular sprays among all non-circular orifice jets
while thinner filaments in circular orifice sprays lead to smaller drop sizes
compared to their triangular counterparts showing the same breakup morphology.
We expect our results to help applications as diverse as engine fuel
combustion, pharmaceutical sprays and CO$_2$ capture by NaOH sprays.
