Volume measurement of atomizing fragments using image slicing

Abstract

The complete structure of atomizing liquid fragments can be analysed by employing multi-dimensional visualization techniques. These techniques require advanced image processing, where objects from multiple views are matched to extract information. However, in higher Weber number sprays, owing to a population of randomly shaped atomizing fragments, matching objects from different imaging frames is very challenging. This paper presents a novel image processing technique to extract volumetric information without a need for matching. The spray is visualized using high speed long-distance microscopy from two perpendicular angles. The developed in-house script employs the principle of image discretisation, where each image is divided into a number of slices and the individual slice from each camera is matched to compute the liquid volume fraction in each image. The volume of individual objects is calculated based on their planar area and orientation. An error analysis is performed using dozens of three-dimensional virtual models of fragment like shapes with known volume. The paper concludes with an analysis of spray volume measured for a range of real twin-fluid atomized cases. The proposed methodology enables the measurement of volume fragments with reasonable accuracy in atomizing sprays with exit Weber numbers of up to around 100. This is a significant extension from an earlier limit of We ~ 20 [1].