风洞环境下喷头及助剂对植保无人飞机 喷雾飘移性的影响 = Effects of nozzle types, adjuvants and environmental conditions on spray drift potential of unmanned aerial vehicles in a wind tunnel

Since the 2010s, unmanned aerial vehicle (UAV) sprayer was applied more and more widely for low-volume aerial pesticides spraying operations in China. However, droplets from the UAV sprayer have a higher drift risk due to more fine droplets sprayed and a higher flight height than ground sprayers. Study on UAV spray drift has been a new hot spot within the field of pesticide application technology. Most of previous studies used direct field methods for spray drift, but the meteorological conditions in field were unstable and uncontrollable, and drift research under an actual operation state in wind tunnel has not been reported. Therefore, 25 treatments of wind tunnel measurements and droplets spectrum tests of 10 models of nozzles were conducted to explore the influence factor on spray drift characteristics of UAV chemicals application in this study. A spray unit with a rotor of UAV was innovatively installed in wind tunnel, and the airstream from the wind tunnel was regarded as the relative moving natural wind to simulate the flight status. The airborne and the sediment spray drift was measured to study the effects of the nozzle type and size (flat fan, hollow cone and air-inclusion nozzles), flight speed, adjuvant (DRS-60, Y-20079, MF and G-611) and meteorological parameters (20°C & 40%, 20°C & 80%, 30°C & 40% and 30°C & 60%). The drift potential (DP) and the drift potential reduction percentage (DPRP) in vertical and horizontal directions were obtained for each test. Both nozzle type and size had an impact on the spray drift potential obviously by affecting the droplet size and the ratio of fine droplets, and the regression linear models between DPRPV/DPRPH and DV50, V75 were established (R2=0.934/0.925). Flight speed also had a significant effect on the spray drift characteristics, and reducing the flight speed could increase the DP effectively. Adding spray adjuvants could affect the DP under experimental meteorological parameters, and the anti-drift performance ranked in the order of DRS-60>MF>Y-20079>G-611. Recommendations were proposed in order to reduce the spray drift for UAV sprayer’s operation. These findings can contribute to provide guidelines and technical support for the wind tunnel spray drift tests of UAV and the field operation regulation of unmanned aerial PPP application. Keywords: unmanned aerial vehicle (UAV) sprayer, wind tunnel, spray drift potential, nozzle, adjuvant DOI: 10.25165/j.ijabe.20201303.5716 Citation: Wang C L, Zeng A J, He X K, Song J L, Herbst A, et al. Spray drift characteristics test of unmanned aerial vehicle spray unit under wind tunnel conditions. Int J Agric & Biol Eng, 2020; 13(3): 13–21.

In the field of pesticide spraying, droplet size is one of the most important factors affecting droplet deposition and drift. In order to study the effect of different droplet size parameters on droplet deposition distribution and drift of aerial spraying by using plant protection UAV, an aerial spraying test with the same spraying rate and different size droplets in rice canopy was carried out by using multi-rotor unmanned aerial vehicles (UAV) and four TEEJET nozzles with different orifice sizes (these droplets with a volume median diameter (VMD) of 95.21, 121.43, 147.28, and 185.09 μm, respectively), and the deposition distribution and penetration of droplets in the target area and the drift distribution of droplets in the non-target area were compared and analyzed. The results showed that the deposition distribution and penetration of droplets in the target area and the drift distribution of droplets in the non-target area were influenced by the droplet size. The droplet deposition rate in the upper and lower rice canopies were increased in the target area with the increase of droplet size. The penetration results of droplets also increased with the increase of droplet size, and that of droplets with a VMD of 185.09 μm was the best, reaching 38.13%. The average values of the cumulative drift rate of droplets in the rice canopy in the four tests were 73.87%, 50.26%, 35.91%, and 23.06%, respectively, and the cumulative drift rate and the drift distance of droplets decreased with the increase of droplet size, which indicated that the increase of droplet size can effectively reduce droplet drift. It demonstrated that the droplet size is one of the most important factors affecting droplet deposition and drift for pesticide spraying by plant protection UAV, and for the application of plant protection UAV with extra-low volume spraying, the use of droplets with VMD less than 160 μm should be avoided and a more than 10 m buffer zone should be considered downwind of the spraying field to avoid drug damage caused by pesticide drift. The results have fully revealed the effect of droplet size parameters on droplet deposition and drift of aerial spraying. Moreover, the influence of the wind field below the rotors on the distribution of droplet deposition was surmised and analyzed from the perspective of plant protection UAV. It is important for optimizing the droplet parameters of aerial spraying, increasing the spraying efficiency, and realizing precision agricultural aviation spray.

As the new favorite of agricultural plant protection operations, the spray characteristics of plant protection unmanned aerial vehicle (UAV) are the key standards to measure their quality, and the quality of spray of plant protection UAV is largely determined by the droplet drift behavior. Thus, recently, the droplet drift in the operation of plant protection UAV has been extensively studied and discussed. This paper proposes a method for studying the effects of three variables on the deposition characteristics and droplet size using a spray performance comprehensive experimental platform (developed by Jilin Agricultural Machinery Research Institute). The 12 groups of spray experiments were carried out with different combinations, rotor speed, spray height and nozzle speed and regression analysis was carried out on the obtained 12 sets of sedimentary characteristics and droplet size data to explore its effects on the deposition characteristics and droplet size. The results show that the spray height has a significant effect on the sedimentation amount, but the influence on the droplet size is negligible. The nozzle rotation speed and rotor rotation speed have a notable effect on the droplet size, but the effect on the sedimentation volume is not significant. This paper can provide theoretical basis and data support for the study of pesticide application techniques to reduce the phenomenon of droplet drift. Keywords: droplet drift, multi-rotor UAV, experimental platform of droplet collection, laser particle size analyzer, centrifugal nozzle DOI:  10.33440/j.ijpaa.20190201.0025  Citation: Zhu H, Jiang Y, Li H Z, Li J X, Zhang H H.  Effects of application parameters on spray characteristics of multi-rotor UAV.  Int J Precis Agric Aviat, 2019; 2(1): 18–25.

Previous research has sought to adopt the use of drift-reducing technologies (DRTs) for use in field trials to control diamondback moth (DBM) Plutella xylostella (L.) (Lepidoptera: Plutellidae) in canola (Brassica napus L.). Previous studies observed no difference in canopy penetration from fine to coarse sprays, but the coverage was higher for fine sprays. DBM has a strong propensity to avoid sprayed plant material, putting further pressure on selecting technologies that maximise coverage, but often this is at the expense of a greater drift potential. This study aims to examine the addition of a DRT oil that is labelled for control of DBM as well and its effect on the drift potential of the spray solution. The objectives of the study are to quantify the droplet size spectrum and spray drift potential of each nozzle type to select technologies that reduce spray drift, to examine the effect of the insecticide tank mix at both (50 and 100 L ha(-1) ) application rates on droplet size and spray drift potential across tested nozzle type and to compare the droplet size results of each nozzle by tank mix against the drift potential of each nozzle. The nozzle type affected the drift potential the most, but the spray solution also affected drift potential. The fine spray quality (TCP) resulted in the greatest drift potential (7.2%), whereas the coarse spray quality (AIXR) resulted in the lowest (1.3%), across all spray solutions. The spray solutions mixed at the 100 L ha(-1) application volume rate resulted in a higher drift potential than the same products mixed at the 50 L ha(-1) mix rate. The addition of the paraffinic DRT oil was significant in reducing the drift potential of Bacillus thuringiensis var. kurstkai (Bt)-only treatments across all tested nozzle types. The reduction in drift potential from the fine spray quality to the coarse spray quality was up to 85%. The addition of a DRT oil is an effective way to reduce the spray solution drift potential across all nozzle types and tank mixes evaluated in this study. The greatest reduction in drift potential can be achieved by changing nozzle type, which can reduce the losses of the spray to the surrounding environment. Venturi nozzles greatly reduce the drift potential compared with standard nozzles by as much as 85% across all three insecticide spray solutions. Results suggest that a significant reduction in drift potential can be achieved by changing the nozzle type, and can be achieved without a loss in control of DBM. © 2016 Society of Chemical Industry.

The reduction of pesticide aerial spraying drift is still one of the major challenges in modern agriculture. The aim of this study was to evaluate the drift potential of different types of unmanned aerial vehicle (UAV) and adjuvant products for reducing spray drift in aerial applications. Three types of UAV (3WQF120-12 and 3CD-15 fuel oil powered single-rotor UAV and HY-B-15L battery powered single-rotor UAV) were selected in this study with regular application parameters to compare each spray drift, and 3WQF120-12 fuel oil powered UAV was selected to quantify spray drift of 6 adjuvants dissolved in water under field conditions. Solutions were marked with brillant sulfoflavin dye (BSF) at 0.1%. Petri dishes and rotary impactors were used to collect airborne and sediment drift, respectively. Drift deposits were evaluated by spectrophotometry in order to quantify deposits. The results showed that when the flight height was 1.5-2.0 m above the crop at the flight speed of 4-5 m/s and the average wind speed of 1.63-1.73 m/s, 3WQF120-12 fuel oil powered UAV had lower drift potential than the other two types; DV0.5 and percentage of droplets with diameter ≤75 μm had very significant effects on spray drift percentage (p=0.01); the risk of drift in agricultural spraying could be significantly decreased not only by reducing the percentage of fine droplets but also by changing droplet spectra. Compared to water, Silwet DRS-60, ASFA+B, T1602, Break-thru Vibrant, QF-LY and Tmax could reduce by 65%, 62%, 59%, 46%, 42%, and 19% spray drift, respectively. when water without adjuvants were sprayed, 90% of drift droplets were located within a range of 10.1 m of the target area while with 0.8% Silwet DRS-60 adjuvant in water, the distance was shortened to 6.4 m. Keywords: spray drift, UAV, adjuvant, aerial application, drift potential evaluation, droplet size DOI: 10.25165/j.ijabe.20181105.3185 Citation: Wang X N, He X K, Song J L, Wang Z C, Wang C L, Wang S L, et al. Drift potential of UAV with adjuvants in aerial applications. Int J Agric & Biol Eng, 2018; 11(5): 54–58.

The development and testing of drift reduction technologies (DRTs) have come to the forefront of application research in the past few years in the United States. DRTs can be spray nozzles, sprayer modifications, spray delivery assistance, spray property modifiers (adjuvants), and/or landscape modifications. A protocol for testing DRTs in high speed wind tunnels has been previously reported and was expanded to test spray nozzles. This manuscript reports on the initial implementation of the DRT program for conducting DRT evaluations of three spray nozzles under high speed conditions (i.e.,45–65 m/s (100–140 mph)), which are relevant to the aerial application of crop production and protection materials. The spray nozzles were evaluated in the USDA-Agriculture Research Service High Speed Wind Tunnel facility. The droplet size of each of the nozzles with different airspeeds, spray pressures, and orientation was measured with a Sympatec Helos laser diffraction instrument. The droplet size spectra for each test were input in a spray dispersion model (AGDISP), which calculates the downwind drift expected from a typical aerial application scenario. As compared to the reference nozzle, the three spray nozzles reduced spray drift by 70–84 % as compared to the reference nozzle. The nozzles generated spray droplets with volume median diameters 60–80 μm larger than the reference nozzle. One of the aerial application industry’s best management practices (BMPs) is to not spray directly on the downwind edge of a field. The spray swath near this edge is moved upwind (i.e., offset) by 1/2 to 1 swath width. When this BMP was combined with the drift reductions from the spray nozzles, the amount of drift reduction was slightly increased; however, application efficiencies increased to 93–96 %. These results demonstrate the possibility of combining multiple drift reduction techniques and technologies to greatly reduce spray drift.

Plant Protection Unmanned Aerial Vehicle(UAV) is the most representative technological product in the construction of precision agriculture in recent years. From direct seeding to areal plant protection, UAV is playing an irreplaceable role. InJapanandChina, UAV plant protection has been adopted by more than 4 million farmers in the past    5 years. The sprayer, as an executive component of the plant protection UAV has also made great progress in the past few years. At present, the sprayers being widely used on UAV platforms are Hydraulic Nozzles and Rotary Atomization Sprayers. This article will detail the two popular sprayers and compare them in field applications. The results showed that the rotary atomization sprayer is more suitable for low-volume and variable-rate spraying, both are not possible by hydraulic nozzles. Since variable spraying is an important functionality for precision agriculture, rotary atomization sprayer will be the direction for future UAV and robot sprayer design. Keywords: Plant protection UAV, precision agriculture, rotary atomization sprayer, hydraulic nozzle, variable spraying DOI:  10.33440/j.ijpaa.20190201.0021  Citation: Gong J Q, Fan W Q, Peng J.  Application analysis of hydraulic nozzle and rotary atomization sprayer on plant protection UAV.  Int J Precis Agric Aviat, 2019; 2(1): 25–29.

Nozzles are the most critical component of a sprayer for pesticide applications. Recently, air-induction nozzles and twin flat-fan air-induction nozzles have started to be used for herbicide applications. In order to evaluate the potential of compact air-induction nozzles for herbicide spraying, this paper compares the effects of air-induction nozzles and standard flat-fan nozzles on spray atomization, deposition, drift, and weed control efficacy in maize and wheat. Droplet spectra were measured by a laser particle size analyzer, and drift potential values were determined using a drift test bench (ISO 22401). A field study was conducted to compare the spray drift and biological efficacy between Lechler standard flat-fan nozzles and compact air-induction nozzles including different nozzle sizes. In the range from 0.2 to 0.4 MPa, the droplet size classes of the LU and ST nozzles were very similar and ranged from fine to very fine, while the droplets of the air-induction nozzles IDK and IDKT were medium or coarse depending on the spray pressure and nozzle size. The drift potential trials showed that the droplet size characteristics, mainly V100, are strongly linked with the drift reduction potential. Both drift potential and field results showed that the compact air-induction nozzles had a good performance in drift reduction. In terms of weed control biological efficacy, there were no significant differences between standard flat-fan nozzles and air-induction nozzles. In all cases, the efficacy values were above 80% both in maize and in wheat. In conclusion, air-induction nozzles are recommended for herbicide applications as they provide good biological efficacy while significantly reducing the amount of spray drift, which is of great significance for the protection of the environment and the surrounding sensitive crops.

Plant protection unmanned aerial vehicles (UAVs), which are highly adapted to terrain and capable of efficient low-altitude spraying, will be extensively used in agricultural production. In this paper, single or several independent factors influencing the deposition characteristics of droplets sprayed by plant protection UAVs, as well as the experimental methods and related mathematical analysis models used to study droplet deposition and drift, are systematically investigated. A research method based on farmland environmental factors is proposed to simulate the deposition and drift characteristics of spray droplets. Moreover, the impacts of multiple factors on the droplet deposition characteristics are further studied by using an indoor simulation test system for the spraying flow field of plant protection UAVs to simulate the plant protection UAVs spraying flow field, temperature, humidity and natural wind. By integrating the operation parameters, environmental conditions, crop canopy characteristics and rotor airflow, the main effects and interactive effects of the factors influencing the deposition of spray droplets can be explored. A mathematical model that can reflect the internal relations of multiple factors and evaluate and analyze the droplet deposition characteristics is established. A scientific and effective method for determining the optimal spray droplet deposition is also proposed. In addition, this research method can provide a necessary scientific basis for the formulation of operating standards for plant protection UAVs, inspection and evaluation of operating tools at the same scale, and the improvement and upgrading of spraying systems.

The droplet size distribution following pesticide application practices can significantly impact droplet drift and non-target organisms (animals and plants). However, the relationship among liquid sheet breakup, drop formation, and droplet drift is an area that has been studied over the past 65 years but is still not fully understood. The objectives of this study were severalfold: to examine the liquid sheet breakup following the use of different adjuvants (sodium dodecyl sulfate, aerosol OT, and silicone at 1%) and their effects on the drift via three commonly used commercial spray nozzles (XR, AIXR, and TXVK). The spray sheet and initial droplet size spectrum for each spray was detected by a particle image velocimetry (PIV) system, and the drift for each treatment was measured in a wind tunnel. The nozzle type and the spray solution were found to significantly affect the liquid sheet breakup characteristics. AIXR produced large droplets, and TXVK with short liquid sheet length produced more small droplets. All adjuvants used in these experiments increased the formation of large droplets upon atomization while simultaneously reducing driftable fines (e.g., drops %<150 µm). The drift potential can be reduced by up to 66.1% when switching from a fine spray quality (TXVK) to a coarse spray quality (AIXR). The SDS adjuvant provided the most effective drift reduction for XR and TXVK nozzles showing reduced drift potential by 69.2% and 66.3%, respectively, while the silicone adjuvant showed the largest drift reduction for AIXR of 78.3%. The correlation between the liquid sheet length and DV0.5 was positive for XR and TXVK nozzles, and there was a significant positive correlation between %<150 µm and drift potential for all nozzles. This work suggests that the drift can be reduced significantly by changing the nozzle type and adding pesticide adjuvant into spray solution, which provided data support for the drift reduction of plant protection drones.

Determination of spray drift and buffer zones in 3D crops using the ISO standard and new LiDAR methodologies

A spraying system for a plant-protection unmanned aerial vehicle (UAV) was designed to reduce spray drift. A custom low-speed wind tunnel was constructed to generate a wind speed ranging from 0 to 5.92 m/s. The results showed that the wind speed was attenuated with an increase in distance. To compensate for the attenuation, a linear-fitting model was adopted. Then, the relationship between the spraying pressure and atomization rate was analyzed, and a fuzzy algorithm was adopted to adjust the spraying angle and pressure according to the wind speed and its changing rate. Finally, an evaluation of the proposed system in the compensated wind tunnel was conducted, and the drift distance was reduced by 33.7% compared with the system without adjustment of the spraying angle and pressure. Keywords: plant-protection UAV, spray drift, spraying pressure, spraying angle, fuzzy algorithm DOI: 10.25165/j.ijabe.20191205.4289 Citation: Chen Y Y, Hou C J, Tang Y, Zhuang J J, Lin J T, Luo S M. An effective spray drift-reducing method for a plant-protection unmanned aerial vehicle. Int J Agric & Biol Eng, 2019; 12(5): 14–20.

Traditional agricultural production requires numerous human and material resources; however, agricultural production efficiency is low. The successful development of plant protection unmanned aerial vehicles (UAVs) has changed the operation mode of traditional agricultural production, saving human, material, and financial resources and significantly improving production efficiency. To summarize the process of improving the productivity of plant protection UAVs, this study established a productivity calculation model of UAVs based on the time composition of the UAV agricultural plant protection process, including spraying, turning, replenishment, and transfer times. The time required for the unmanned aircraft application process was counted through years of tracking the application process of eight different plant protection unmanned aircraft. Plot lengths of 100, 300, 500, 700, 1,000, 1,500, 2,000, 2,500, 3,000, and 3,500 m were established to calculate the theoretical productivity. The results showed that the productivity of different types of plant protection UAVs increased with an increase in plot length in the range of 100 to 1,500 m; however, when the plot length reached a certain value, the productivity growth rate slowed down or even decreased slightly. Simultaneously, based on the working area per 10,000 mu, the recommended plot length and the number of configured models for different models were recommended. If the plant protection UAV was distinguished by electric and oil power, the time utilization rate of electric plant protection UAVs was 72.7%, and the labor productivity was 56.4 mu/person·h. In contrast, the time utilization rate of the heavy load oil-powered plant protection unmanned aircraft was 86%, and the labor productivity was 63.5 mu/person ·h. This study can support plant protection UAV enterprises to optimize equipment efficiency, provide evaluation methods for the operation efficiency assessment of plant protection UAVs, provide a reference for the selection of plant protection UAVs, and provide a basis for field planning.

To address the technical problems of broad droplet size spectrum, insufficient atomization uniformity, and spray drift in plant protection unmanned aerial vehicle (UAV) applications, this study developed a novel two-stage aerial electrostatic spraying device based on the coupled mechanisms of hydraulic atomization and electrostatic induction, and, through the integration of three-dimensional numerical simulation and additive manufacturing technology, a new two-stage inductive charging device was designed on the basis of the traditional hydrodynamic nozzle structure, and a synergistic optimization study of the charging effect and atomization characteristics was carried out systematically. With the help of a charge ratio detection system and Malvern laser particle sizer, spray pressure (0.25–0.35 MPa), charging voltage (0–16 kV), and spray height (100–1000 mm) were selected as the key parameters, and the interaction mechanism of each parameter on the droplet charge ratio (C/m) and the particle size distribution (Dv50) was analyzed through the Box–Behnken response surface experimental design. The experimental data showed that when the charge voltage was increased to 12 kV, the droplet charge-to-mass ratio reached a peak value of 1.62 mC/kg (p < 0.01), which was 83.6% higher than that of the base condition; the concentration of the particle size distribution of the charged droplets was significantly improved; charged droplets exhibited a 23.6% reduction in Dv50 (p < 0.05) within the 0–200 mm core atomization zone below the nozzle, with the coefficient of variation of volume median diameter decreasing from 28.4% to 16.7%. This study confirms that the two-stage induction structure can effectively break through the charge saturation threshold of traditional electrostatic spraying, which provides a theoretical basis and technical support for the optimal design of electrostatic spraying systems for plant protection UAVs. This technology holds broad application prospects in agricultural settings such as orchards and farmlands. It can significantly enhance the targeted deposition efficiency of pesticides, reducing drift losses and chemical usage, thereby enabling agricultural enterprises to achieve practical economic benefits, including reduced operational costs, improved pest control efficacy, and minimized environmental pollution, while generating environmental benefits.

Extensive research has been conducted on plant protection unmanned aerial vehicle (UAV) chemical application technology in recent years owing to its importance as a means of pest and disease control. UAV spraying in orchards faces the drawback of drift risk and can be hazardous to non-targeted crops, humans, and the environment. A detailed and systematic analysis must be performed to determine the uniformity and drift risk of plant UAV sprays. In this study, a peach orchard is sprayed with a plant-protection UAV at three different flight velocities and we evaluate the combined pesticide deposition performance of the canopy, ground loss, downwind ground drift, and airborne drift. Additionally, the droplet size and coverage rate in the canopy are calculated by using water-sensitive paper. The results demonstrate that there is significant difference in the droplet size at flight velocities of 1–3 m/s. The droplet size in the lower canopy is slightly smaller than those in the middle and upper parts. Increasing the flight velocity helps the pesticide droplets to spread and penetrate the canopy. However, it also causes a non-uniform pesticide deposition, reduced effective coverage ratio and effective density ratio. Among the three pesticides used in the experiment, imidacloprid exhibits the best deposition efficiency. The deposition amount and normalized deposition amount in the canopy were the highest at a flight velocity of 2 m/s, accompanied by a lower ground loss under the canopy. The highest near-field ground drift is observed at a velocity of 1 m/s, and the far-field airborne drift is highest at 3 m/s. Lastly, this study provides a reference for the commercial application of plant-protection UAVs.