For dense sprays such as those encountered in diesel or gasoline direct injection, the interpretation of spray images
is complicated by the fact that most of the light reaches the detectors after multiple scattering events within the
spray. This may introduce severe errors when extracting quantitative or even qualitative information from these
images as many diagnostics rely on the assumption of single photon scattering.
It has recently been shown that the multiple scattering component of spray images can be effectively suppressed if
sets of structured light sheets are used to illuminate the spray. The aim of this report is to illustrate the potential
and the limitations of this technique for the visualization of sprays from modern diesel and gasoline injectors
at elevated atmospheric pressures. The results clearly show that conventionally recorded images are dominated
by multiple scattering, causing the light sheet to widen substantially and obscuring details within the light sheet
plane. In contrast, multiple scattering and indirect reflections can be suppressed using structured light sheets and
proper image processing. Careful interpretation of the corresponding images reveals details of the inner spray
structure and thus contributes to the understanding of the complicated spray break-up and atomization processes.