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Planar droplet sizing techniques, such as laser induced fluorescence (LIF) to Mie ratio imaging, have the potential to capture large amounts of spatially resolved droplet size information quickly. In order to do so reliably however, an accurate calibration is required. This work focuses on the assessment of a Sauter-mean diameter calibration methodology applied to LIF/Mie ratio-metric images. The aim here is to determine the range of applicability of this calibration approach, as well as its effectiveness by determining the uncertainties of the resulting planar droplet size map. The images used to proof this methodology were collected using structured laser illumination planar imaging (SLIPI) on sprays from a simple pressure atomizer under elevated ambient pressures. Three liquids were used in these experiments: nozzle calibration fluid, conventional jet fuel and a high viscosity alternative jet fuel. Fuel flows ranged from 2 g/s to 5 g/s, and the ambient pressure was varied between 1.1 and 10 atm. The results of the study show that this calibration method generates similar calibration curves at a wide range of operating conditions and can be approximated by a logarithmic function. The data also show that the calibration curve is agnostic to the fuel mass flow rate, but is dependent on ambient air pressure.
