When chemicals are sprayed to control weeds and plant diseases, the resulting spray droplet size distribution is an important factor as it can influence the coating efficiency of the spray and the risk of off-target spray deposition. Droplets that are too large cannot effectively cover the sprayed area while droplets that are too small run the risk of being carried off-target by the wind- which is also known as ‘spray drift’. Spray drift can potentially damage other crops, waterways and can affect human health. To control spray drift, one needs to understand the macro as well as micro scale dynamics during spraying, for which the low-speed agriculture spray wind tunnel is designed and built.
We invest the properties of agriculture sprays, with an aim towards understanding how to reduce spray drift through controlling the sprayed tank mix, using a low-speed wind tunnel. The facility allows researchers to understand spray characteristics at different spray settings in a well-controlled environment. It is equipped with two state-of-the-art measurement techniques (i) Laser Diffraction (LD) and (ii) Digital Inline Holography (DIH). LD is used to provide information on the droplet size distribution of the spray while DIH (done in collaboration with Professor Jiarong Hong’s group) is used for the visualization and can get more data (individual droplet size, velocity, and direction, etc.).