Engineering Models of Air Assistance Orchard Sprayers

Walklate, P. J.; Weiner, K.-L.

doi:10.17660/actahortic.1994.372.9

Cited by 4 publications

(2 citation statements)

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“…Following earlier studies by Walklate and Weiner (1994), a CFD model simulating airflow from air-assisted orchard sprayers with one, two and four fan configurations has been validated (Endalew et al, 2010a,b,c) and showed that more uniform distribution within the crop canopy was achieved with the four fans mounted in a vertical column (Airjet Quatt sprayer), except for minor peaks at the fan positions. Following earlier studies by Walklate and Weiner (1994), a CFD model simulating airflow from air-assisted orchard sprayers with one, two and four fan configurations has been validated (Endalew et al, 2010a,b,c) and showed that more uniform distribution within the crop canopy was achieved with the four fans mounted in a vertical column (Airjet Quatt sprayer), except for minor peaks at the fan positions.…”

Section: Orchard Sprayersmentioning

confidence: 99%

Air‐assisted sprayers

2014

Pesticide Application Methods

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The provision of an airflow to assist in the distribution of pesticides within crop canopies has led to a number of sprayer designs with different fan systems and configurations of a range of nozzle types. Generally, the interest in the use of air-assisted sprayers has increased since Potts (1958) recognised the ability to reduce spray volumes significantly by using an airflow to project droplets into a crop canopy. Traditionally used for treating tree crops, air-assisted sprayers have now been adopted in many other types of crop. Downwardly directed air assists droplet penetration of arable field crop canopies and in reducing downwind drift (Figure 8.1).However, registration authorities are concerned that when spraying orchards, small droplets can drift above the tree canopy (Gil et al., 2007(Gil et al., , 2008 and outside orchards so buffer zones are wider for this type of application. Reyes et al. (2012) have developed a data acquisition system to assess the quality of spraying and verify whether the weather conditions were appropriate when a spray was applied.Various terms have been used in association with air-assisted spraying. These include 'concentrate', 'mistblower' and 'air-carrier' spraying. Mistblowers are sprayers that produce droplets in the 50-100 μm size range as these droplets are most effectively conveyed within an airstream. Potts (1958) found that in a particular airstream, droplets of 60-80 μm diameter were carried 46 m, while the larger 200-400 μm droplets travelled only 6-12 m. Larger droplets will be influenced more by gravity, while the smallest droplets are less likely to impact on foliage and other targets as they remain within the airstream. This is particularly important when projecting spray upwards into a tree canopy as fall-out due to gravity can result in considerable wastage of pesticide on the ground as well as increasing risk of operator exposure to the pesticide. However, with greater concern about spray drift out of orchards, coarser sprays are increasingly selected. The distance that large droplets are transported depends very much on the strength of the air assistance and the initial direction of trajectory of the droplets. As the risk of spray drift from orchards is considered to be greater than from arable crops, the unsprayed buffer zone (UBZ) in the UK is at least 18 m, although when using a tunnel sprayer, this is reduced to 5 m.

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Section: Orchard Sprayersmentioning

confidence: 99%

Air‐assisted sprayers

2014

Pesticide Application Methods

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“…It has been used to model the spray drift generated by air-assisted sprayers (Weiner & Parkin, 1993;Walklate & Weiner, 1994). Over time, CFD has been shown to be a useful and complementary tool for carrying out the complex and costly tests required to investigate the phenomenon of drift .…”

Section: Introductionmentioning

confidence: 99%

Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

Salcedo¹,

Garcerá²,

Granell³

et al. 2015

Span. j. agric. res.

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Atmospheric drift of plant protection products is considered a major source of air pollution during pesticide applications. Citrus protection against pests and diseases usually requires application of these products using air-blast sprayers. Many authors have emphasized the influence of vegetation on the risk of spray drift. The aim of this work was to describe in detail how the airflow from an air-blast sprayer behaves when it reaches citrus trees and, in particular, the effect that the tree canopy has on this flow. Tests were conducted at a commercial citrus orchard with conventional machinery, placed parallel to a row of trees. Air velocity and direction was measured using a 3D ultrasonic anemometer in 225 points situated in three parallel planes perpendicular to the equipment. The stability of the airflow at each measuring point was studied and the mean velocities were graphically represented. Two vortexes, one behind the canopy, and another over the tree, have been deducted and never been reported before. Both may have an important influence on the trajectories of the sprayed droplets and, as a consequence, on the way in which plant protection products are diffused into the atmosphere. Observed turbulence intensities were higher than in similar experiments conducted in other tree crops, which may be attributable to the higher air volume generated by the machinery used for citrus protection and to the higher foliage density of citrus orchards.

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Air‐Assisted Sprayers

Matthews

2000

Pesticide Application Methods

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Engineering Models of Air Assistance Orchard Sprayers

Cited by 4 publications

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Air‐assisted sprayers

Air‐assisted sprayers

Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

Air‐Assisted Sprayers

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