Effect of polydispersity in droplet-driven flows

Experiments were performed on agricultural flat-fan sprays to elucidate the effect of polydisperse droplets on air induction and entrainment process using shadowgraphy and PIV. Results indicated air motion in flat-fan sprays being close to elliptical jet in terms of its growth, but velocity decay to be dependent on spray spread angle and particle size distribution. Continuous transfer of momentum from droplets of all sizes to air was observed across all measurement planes, with the velocity of smaller droplets dropping quicker to match induced air velocity values than larger ones. Most of the droplets traversed almost in a ballistic manner with only a small fraction of them interacting with air. Experiments in interacting sprays presented greater uniformity in droplet sizes, and near constant unidirectional droplet and air velocities over larger distances.