Drop Size and Drop Size Distribution Measurements by Image Analysis

J. Blaisot (1)

1 CORIA - Complexe de recherche interprofessionnel en aérothermochimie

One important issue in drop sizing by image analysis is the determination of the contour of the drops. The grey level corresponding to this contour strongly depends on the degree of focusing of a drop. This grey level is determined from an imaging model based on Fourier optics formalism. The presented method allows estimating the correct contour of a focused or of an out-of-focus droplet, for a large range of sizes. A size-independent criterion for the selection of drops accordingly to their position relative to the focus plane is also presented. This criterion is based on the estimation of the PSF width. The criterion is used to select drops within a controlled range of out-of-focus positions, which is necessary for the determination of drop size distributions in spray applications. The method is applied to calibrated objects to control the method accuracy. Sources of sizing errors are evaluated and techniques to enhance the sizing procedure and to deal with overlapped images are presented.

Domaines: Mécanique des fluides [physics.class-ph]; Traitement du signal et de l'image [eess.SP]

J. Blaisot. Drop Size and Drop Size Distribution Measurements by Image Analysis. International Conference on Liquid Atomization and Spray Systems, Sep 2012, Heidelberg, Germany. ⟨hal-02372393⟩