The Effect Of Spray Structure Of Oil-Based Emulsion Spray On The Droplet Characteristics

Oil-based emulsions are commonly formulations in agricultural spraying but their spray break-up behaviour and droplet characteristics differ from those when water is sprayed. In this paper, the effect of spray structure on the droplet characteristics, droplet size distribution and droplet velocity, were investigated using the high-speed photomicrography and image processing. Formation of the typical spray structure and the effect of emulsion concentration and spray pressure on the spray structure and droplets characteristics were analysed. Results show that the use of oil-based emulsion decreases the liquid sheet area and the flapping form of break-up when compared to water sprays and it is this change that is responsible for the increase of droplet size. Thus, oil-based emulsion sprays have a narrower droplet size distribution due to the limited amount of liquid sheet flapping and the subsequent changes break-up structure. The decrease of flapping increases the velocity the droplets in oil-based emulsion spray by 43% compared with the water spray. Emulsion sprays typically have both flapping and perforating break-up mechanisms when the emulsion concentration is low and the spray pressure is high. The results in this paper indicate that the perforating break-up mechanism can dominate the flapping mechanism when spray pressure is 0.3 MPa and the emulsion concentration 0.1%. (c) 2020 IAgrE. Published by Elsevier Ltd. All rights reserved.