SLIPI-LIF/Mie For Droplet Sizing In 3D: A Study Of Calibration Variations As A Function Of Injection Pressure

Abstract

SLIPI-LIF/Mie (standing for Structured Laser Illumination Planar Imaging Laser-Induced Fluorescence / Mie scattering ratio) is a well-recognized technique for providing spatially resolved 2D measurement of the droplet Sauter Mean Diameter (SMD) within optically dense sprays. This can indeed be achieved as the SLIPI approach allows suppressing the unwanted intensity contribution of multiple light scattering. For droplet sizing, a calibration procedure is then required, where the LIF/Mie intensity ratio as a function of the SMD is deduced, using for example Phase Doppler Anemometry (PDA). We show here that for a given operating condition a single calibration curve is reliable at any position in the spray. However, we observe that this calibration is dependent on the liquid injection pressure. Thus, the calibration curves must be modified for each injection pressure employed. The knowledge of this calibration curve variation is essential during any parametric spray study, where the operating conditions are modified. The need of performing the calibration procedure in the exact same conditions than for the experimental measurements is shown here. A correction of the calibration curve as a function of injection pressure is also proposed in this article. Note that further investigations will be needed to understand the observed trend. Finally, the methodology has been applied over a series of 15 planes spaced by 2 mm to reconstruct the droplet SMD in 3D.