  A thorough numerical, theoretical and experimental investigation of the
liquid atomization in a full cone pressure swirl nozzle is presented. The first
part is devoted to the study of the inner flow. CAD and CFD software are used
in order to determine the most important parameters of the flow at the exit of
nozzle. An important conclusion is the existence of two flow regions: one in
relatively slow motion (the boundary layer) and a second nearly in solid
rotation at a very high angular rate (about 100 000 rad/s) with a thickness of
about 4/5th of the nozzle section. Then, a theoretical and experimental
analysis of the flow outside the nozzle is carried out. In the theoretical
section, the size of the biggest drops is successfully compared to results
stemming from linear instability theory. However, it is also shown that this
theory cannot explain the occurrence of small drops observed in the stability
domain whose size are close to the Kolmogorov and Taylor turbulent length
scale. A Phase Doppler Particle Analyser (PDPA) is used to characterize the
droplet size and velocity distribution. Due to centrifugal force, the smaller
droplets tend to prevail on the spray axis and a peak close to the Taylor
length scale appears progressively in the PDF when increasing the distance from
the nozzle. It is then assumed that these small droplets are the results of a
turbulent cascading atomization process and that in the near nozzle area, since
centrifugal segregation is small, PDF can therefore be fitted with a log-stable
law (Rimbert and S\'ero-Guillaume, 2004). The value of the stability index is
found to be 1.35 very close to a previous experimental result of 1.39 (Rimbert
and Delconte, 2007) but far from a known theoretical value of 1.70 (Rimbert,
2010). This let think about a slightly different underlying process due to the
helical nature of the turbulence.
