Single Shot SLIPI LIF/Mie Ratio for Droplet Sizing in DISI-Sprays

Abstract:
This paper reports on the first realization of two-phase SLIPI (Structured Laser Illumination Planar Imaging) in combination with LIF/Mie ratio imaging for a single shot mapping of relative SMD (Sauter Mean Diameter) in a transient fuel spray. The technique is applied to a non-combusting multi-jet DISI (direct-injection spark-ignition) spray of ethanol fuel injected into an optically accessible constant volume chamber. The organic dye Eosin is added to the fuel as a laser-induced fluorescence (LIF) tracer when illuminated by the 532nm laser sheet. It is found that SLIPI produces more reliable relative SMD distributions in comparison to the conventional LIF/Mie-approach. Multiple scattered light is suppressed by the SLIPI technique and the background spray plumes and artifacts behind the illuminated plane are successfully suppressed. The single-shot SLIPI images give a clear insight into the highly turbulent liquid spray structure and provide reliable information on the spatial droplet distribution.