Direct numerical simulations of the evaporation of dilute sprays in turbulent swirling jets

The effects of swirled inflows on the evaporation of dilute acetone droplets dispersed in turbulent jets are investigated by means of direct numerical simulation. The numerical framework is based on a hybrid Eulerian–Lagrangian approach and the point-droplet approximation. Phenomenological and statistical analyses of both phases are presented. An enhancement of the droplet vaporization rate with increasing swirl velocities is observed and discussed. The key physical drivers of this augmented evaporation, namely dry air entrainment and swirl-induced centrifugal forces acting on the droplets, are isolated with the aid of additional simulations in which the inertial properties of the droplets are neglected. The correlation between swirl and dry air entrainment rate is found to be responsible for the increase of the global evaporation rate and the spray penetration length reduction, while swirl-induced centrifugal forces are found to be effective only in the jet shear layer, close to the injection orifice, for the analyzed cases.