CFD simulation and experiment on the flow field of air-assisted ultra-low-volume sprayers in facilities

Xinyu Lu,Guo Wang,Yan Gong,Xiao Chen,Qiuhan Liang,Xiao Zhang,Dejiang Liu

doi:10.25165/j.ijabe.20211402.6013

Abstract

In order to explore the performance of the B-ULV-616A knapsack sprayer, computational fluid dynamics (CFD) was used to simulate the B-ULV-616A knapsack air-assisted device, which features an ultra-low-volume electric sprayer. Field experiments were carried out to test the spraying effects, and the KANOMAX anemometer was used to verify the simulated results. First, the internal and external flow fields and droplet deposition distribution of the ultra-low-volume sprayer were established. The results showed that the air-assisted spray device can change the airflow speed and direction and produce a high-speed swirling airflow at the outlet of the air-assisted spray device. The high-speed airflow (maximum of 83.5 m/s) generates negative pressure (minimum of 0.099 MPa) and causes a rapid increase in the droplet velocity and a secondary droplets spray, allowing droplets to reach a longer distance. Then, the maximum relative error was 20.14%, and its average value was 9.59%, indicating that the CFD method is suitable for the flow field analysis of the air-assisted spray device. Finally, based on the greenhouse experiment, the knapsack air-assisted ultra-low-volume electric sprayer was found to effectively improve the deposition on the rear of the crop, increase the droplet density (maximum of 81/cm2; droplet density of conventional electric sprayer is 64/cm2), and reduce the deposition amount and coefficient of variation (below 20%) within and between regions. Further, it managed to reduce pesticide use (by 69.85%) and rural non-point source pollution. Keywords: CFD simulation, air-assisted sprayer, ultra-low spraying rate, deposition, air-velocity field, relative error DOI: 10.25165/j.ijabe.20211402.6013 Citation: Lu X Y, Gong Y, Liu D J, Wang G, Chen X, Zhang X, et al. CFD simulation and experiment on the flow field of air-assisted ultra-low-volume sprayers in facilities. Int J Agric & Biol Eng, 2021; 14(2): 26–34.

Highlights

In order to explore the performance of the B-ULV-616A knapsack sprayer, computational fluid dynamics (CFD) was used to simulate the B-ULV-616A knapsack air-assisted device, which features an ultra-low-volume electric sprayer
Dekeyser et al.[18] used CFD simulation and experimental verification methods to study the parameters of nozzles, droplet size distribution, and wind field airflow on three commercially available air-assisted sprayers with different air-feeding devices
Qi et al.[22] established the droplet deposition distribution model of the HardiLB-255 orchard air-assisted sprayer, while Wang et al.[23] determined the time required by the droplets to attach to the target crop surface

Summary

Introduction

In order to explore the performance of the B-ULV-616A knapsack sprayer, computational fluid dynamics (CFD) was used to simulate the B-ULV-616A knapsack air-assisted device, which features an ultra-low-volume electric sprayer. Based on the greenhouse experiment, the knapsack air-assisted ultra-low-volume electric sprayer was found to effectively improve the deposition on the rear of the crop, increase the droplet density (maximum of 81/cm; droplet density of conventional electric sprayer is 64/cm2), and reduce the deposition amount and coefficient of variation (below 20%) within and between regions. Dekeyser et al.[18] used CFD simulation and experimental verification methods to study the parameters of nozzles, droplet size distribution, and wind field airflow on three commercially available air-assisted sprayers with different air-feeding devices. Garcerá et al.[20] conducted an application study on citrus trees using an axial-flow air blower sprayer and a pneumatic sprayer They compared the application results of the standard cone and Venturi nozzles and proved that the airflow can effectively reduce droplet drift and deposition losses. The results provide a reference for the further research and development of new spray components in precision spraying equipment and their efficient application in pest-control greenhouse crops

Methods

Results

Conclusion