Spray Drift from Hydraulic Spray Nozzles: the Use of a Computer Simulation Model to Examine Factors Influencing Drift |
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| Institution: | 1. Academy of Interdisciplinary Studies, Guangdong Polytechnic Normal University, Guangzhou 510665, China;2. College of Engineering, Huazhong Agricultural University, Wuhan 430070, China;3. College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China;1. School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China;2. Department of Agricultural Engineering, Faculty of Agriculture Science and Technology, Bahauddin Zakariya University, Multan 60800, Pakistan;3. Department of Farm Power and Machinery, Faculty of Agricultural Engineering, Sindh Agriculture University, Tando Jam 70060, Pakistan;1. Universitat Politècnica de Catalunya, Department of Agro Food Engineering and Biotechnology, Esteve Terradas, 8, 08860 Castelldefels, Spain;2. Università di Torino, DISAFA, Largo Paolo Braccini, 2, 10095 Grugliasco, Italy;3. Universitat Politècnica de Catalunya, Chemical Engineering Department, Av. Diagonal 647, 08028 Barcelona, Spain;1. Department of Mechanical System Engineering, Graduate School, Jeonbuk National University, Republic of Korea;2. National Institute of Agricultural Science, RDA, Republic of Korea;3. Division of mechanical system Engineering, Jeonbuk National University, Republic of Korea |
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| Abstract: | The effects on spray drift of nozzle size, angle and operating pressures for boom-mounted hydraulic nozzles operating over a range of meteorological and crop conditions, was investigated using computer simulation. The results showed that the measurements of droplet size, particularly the percentages of spray volume in droplets less than 100 μm in diameter, critically influenced spray drift. Measurements made with an optical imaging system gave data which showed insensitivity to some of the parameters studied, in particular, nozzle size. Results using measurements from this instrument indicated greater spray drift from 80° nozzles mounted at 0·5 m above the crop than from 110° nozzles operating over a comparable range of flowrates and positioned 0·35 m above the crop, despite the coarser spray quality produced by the nozzle with the smaller fan angle. Further simulations were carried out using data from a Phase Doppler analyser in which better resolution of size was possible at droplet diameters <100 μm. Using this data, the model indicated an increase in the mass flux of down-wind airborne spray in conditions that encouraged evaporation; this effect was probably over-estimated because of the assumed constant local air moisture content.Spray drift was shown to increase approximately linearly with wind speed; the rate of increase for a given spray sheet angle and operating pressure was a function of nozzle size. The simulation was also used to demonstrate that a measurement of wind speed made at a height of 2 m above a tall crop signifies a greater drift hazard than the same wind speed measured over a short crop at the same height above the ground. |
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