The prize was awarded for the paper “Multiple scattering reduction in instantaneous gas phase phosphor thermometry: applications with dispersed seeding”, which focuses on the measurement of flow temperatures in fluids. The authors from Darmstadt are Michael Stephan, Florian Zentgraf, Barbara Albert, Benjamin Böhm and Andreas Dreizler.
In the study, laser diagnostic measurement techniques are merged and advanced to enable a two-dimensional temperature field measurement in fluid flows with high temporal and spatial resolution and reduced bias from multiple scattering. For this purpose, a technique called Structured Laser Illumination Planar Imaging (SLIPI) is combined with laser-induced gas phase phosphor thermometry. The first approach applies a spatial structure to the laser light sheets used for excitation, resulting in a light/dark pattern of the sheets (see left half of the image). The emission signal in regions with no laser intensity can be interpreted as multiple scattering and thus removed in an algorithmic reconstruction.
The latter gas phase phosphor thermometry uses temperature sensitive particles dispersed in the flow under investigation. The laser induced luminescence emission is captured and represents the fluid temperature (see right half). In combination of these techniques, it is possible to measure temperature fields with a significantly reduced bias originating from multiple scattering or diffuse scattering from solid surfaces, compared to conventional light sheet imaging. Within the study, different approaches and reconstruction strategies are implemented, evaluated and compared.
The developed approach is seen beneficial in highly particle-laden environments prone to cause multiple scattering (e.g. having several walls). This could help improve spray measurements in optically accessible research engines or turbines.