Numerical study of the secondary atomization characteristics and droplet distribution of pressure swirl atomizers

Abstract

The droplet distribution in a spray field directly represents the secondary atomization of the spray field, an issue that is currently receiving significant attention in engineering research. In this study, based on a simple pressure swirl atomizer, the atomization process is numerically simulated by using coupled calculations of internal and external flow at different pressure drops, and the corresponding experimental measurements were also made. For different pressure drops, the numerically calculated macroscopic morphology of the spray field is consistent with the experimental results, and the maximum differences in the numerically calculated average diameter, spray angle, and flow rate are 8.2%, 6.7%, and 9.5%, respectively. The droplet-size distributions in simulation and experiment are acquired in the spatial and temporal domains, respectively, and are quantitatively analyzed in the former by fitting with a probability density function. The advantage of simulations is that they are not affected by the random fluctuations in measurement position and can thus accurately and comprehensively characterize the spatial distribution and atomization characteristics of droplets in the entire spray field, which is conducive to the overall analysis of the spray field and to the prediction of a high-temperature zone in the combustion chamber. This study should thus advance the macroscopic understanding of the overall spatial distribution of the spray field and provide a reference method for the design and optimization of pressure swirl atomizers in engineering applications.