Experimental investigation of atomization through an optically accessible pressure swirl atomizer is presented. High-speed imaging is used for analysis of air core formation and liquid sheet dynamics, while PDA measurements are used for analysis of the spatial evolution of droplet size, two-phase flow, and interactions thereof. The effect of inlet conditions on the air core formation and thereby on the external spray morphology is studied; strong correspondence is observed. The liquid sheet thickness at the nozzle exit and the proper orthogonal decomposition (POD) analysis of the corresponding conical liquid sheets validated the applicability of the inviscid theory for water sprays. The predictions from the popular inviscid breakup theory [Senecal et al. (1999) and Dombrowski showing a very good agreement with experiments. Furthermore, the spatial evolution of droplet size and two-phase flow is analyzed as a function of nozzle exit conditions. The combined analysis of air core formation, liquid sheet breakup, and two-phase interaction is carried out, leading to a comprehensive understanding of pressure swirl atomization of a rather low-viscosity fluid through a state-of-the-art pressure swirl atomizer. • A comprehensive experimental and inviscid analysis of pressure swirl atomization. • The study uses a geometrically scaled-up and optically accessible atomizer. • Interplay between air core formation, breakup, and two-phase flow is studied. • Classical inviscid models for air core formation and breakup characteristics are evalauted. • A modified inviscid model for conical liquid sheet breakup is presented. • Systematic delineation of the coupled processes is established.
Swami et al. (Fri,) studied this question.