Spray is an efficient tool in the usage whose primary objectives are to obtain droplets with increased liquid surface area and more dispersed liquid over a larger volume. The determination of spray characteristics has been a topic of extensive research recently. In the present investigation, the flow structure of a spray issuing from an oil burner nozzle was determined in a parametrical manner. The main tool in the experimental research is the Interferometric Particle Imaging (IPI) configuration. This method exploits the interference between light reflected from and refracted through individual transparent spray droplets which are illuminated by a laser light sheet in a wide angle forward-scatter region. Based on a scattering theory, the droplet diameter of spray particles can be related to the light pattern scattered from that particle. In addition, using double-framed images also enables the calculation of velocities associated with these particles. In this way, as a representation of spray structure, the droplet size and velocity distributions were obtained prior to a change in the primary parameters of liquid flow e.g. surface tension, viscosity, density and the injection pressure. The evolution of spray characteristics in space were also examined by conducting measurements in different radial and axial locations relative to spray centerline.

Les structures immergées telles que des hydroliennes génèrent des écoulements turbulents pouvant fortement perturber les fonds marins. La compréhension de l’impact de la présence de ces structures nécessite de comprendre la dynamique tridimensionnelle des tourbillons qu’elles génèrent. Les méthodes optiques, par leur aspect non intrusif, permettent d’analyser de telles dynamiques. L’imagerie interférométrique en défaut de mise au point est une technique développée à l’originepour la mesure de taille de particules sphériques transparentes telles que des gouttes ou des bulles. Nous proposons ici l’extension de cette technique à la mesure simultanée de particules irrégulières et sphériques. Un premier montage expérimental a permis de valider la méthode pour la mesure de taille et de position tridimensionnelle de grains de sable et de bulles d’air dans l’eau. Un second dispositif a été réalisé sur un canal à houle de plus grandes dimensions, permettant d’introduire les notions de suivi tridimensionnel de particules irrégulières et d’analyse de variation de leur orientation. Un troisième montage composé de deux dispositifs d’imagerie interférométrique selon deux angles d’observations est utilisé pour la reconnaissance de forme de différentes familles de particules irrégulières. Grâce à des comparaisons avec des simulations, les dimensions et l’orientation de ces particules sont déterminées. Ce type de montage devrait être adapté à la caractérisation de cristaux de glace dont divers types de formes sont connus. Ces travaux ouvrent des perspectives pour l’extension de la technique aux mesures de vitesses de particules dans des écoulements hostiles, combinées avec la reconnaissance de forme et la détermination de la rotation de particules. / Submerged structures such as tidal turbines generate turbulent flows that can strongly disrupt the seabed. Understanding the impact of the presence of these structures requires understanding the three-dimensional dynamics of the vortices they generate. Optical methods, by their non-intrusive aspect, make it possible to analyze these dynamics. Interferometric Particle Imaging is a technique originally developed for the measurement of transparent spherical particles such as droplets orbubbles. We offer here an extension of this technique for the simultaneous characterization of irregular and spherical particles in a flow. A first experimental set-up has confirmed the validity of the method for the size and three-dimensional position measurement of grains of sand and air bubbles in water. A second device was used on a wave flume of bigger dimensions, introducing the notions of three-dimensional tracking of irregular particles and the analysis of the variation of their orientation.A third device made of two Interferometric Particle Imaging set-ups at two angles of observation is described for the shape recognition of different families of irregular particles. Through comparisons with simulations, dimensions and orientations of these particles are determined. This kind of device should be suitable for the characterization of ice crystals for which various shapes are known. The prospects that such results provide include the extension of the technique to the particle velocitymeasurement in hostile conditions, combined with the shape recognition and the determination of rotation of particles.