The present study focuses on the influence of gas swirl on the spray behaviour from a two-fluid coaxial atomiser with high gas-to-liquid dynamic pressure ratios M by varying both the liquid Reynolds number Reₗ and the gas Weber number Weg. The investigations identify the deviations of the carrier phase velocity fields, droplet distribution, and dispersion when swirl is introduced to the gas phase compared with the non-swirling conditions. The changes in the axial, radial and tangential velocities of the continuous phase due to the introduction of swirl are highlighted while retaining a self-similar behaviour. The slip velocity of the large droplets in swirling sprays is negative, unlike the known positive value for non-swirling sprays. The shape of the radial profiles of the mean drop size is investigated along Weg, notably revealing an inflection point for swirling sprays at high- Weg values. A global assessment of the drop size uncovered that swirl leads to its increase for low M while assisting spray formation at high M. Additionally, the radial profiles of axial fluxes for swirling sprays have a wider bell-shaped curve compared with non-swirling sprays at high M, unlike the off-centre maxima found for low M. However, the mentioned dependencies of drop sizes and fluxes cannot be determined by M solely for intermediate gas-to-liquid momentum ratios (23 M 46), and vary with Reₗ and Weg. In addition, the response of at least the mean droplets at the edge of the spray to the large gas eddies shows a linear relation with swirl intensity.
Sahoo et al. (2025) studied this question.