2021/08/25 by A. Gaillard, Gaillard, A., R. Sijs +3
Agricultural and Biological Sciences · Engineering · #Electrohydrodynamics and Fluid Dynamics #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Heat Transfer #Plant Surface Properties and Treatments #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.2108.11163
openalex publication_date 2021/08/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The effect of viscoelasticity on sprays produced from agricultural flat fan nozzles is investigated experimentally using dilute aqueous solutions of polyethylene oxide (PEO). Measurements of the droplet size distribution using laser diffraction reveal that polymer addition to water results in the formation of overall bigger droplets with a broader size distribution. The median droplet size D50 is found to increase linearly with the extensional relaxation time of the liquid. The non-dimensional median droplet sizes of different polymer solutions, sprayed at different operating pressures from nozzles of different sizes, rescale on a single master curve when plotted against an empirical function of the Weber and Deborah numbers. Using high-speed photography of the spraying process, we show that the increase in droplet size with viscoelasticity can be partly attributed to an increase of the wavelength of the flapping motion responsible for the sheet breakup. We also show that droplet size distributions, rescaled by the average drop size, are well described by a compound gamma distribution with parameters n and m encoding for the ligament corrugation and the width of the ligament size distribution, respectively. These parameters are found to saturate to values n=4 and m=4 at high polymer concentrations.