Droplet Deposition Characteristics Research Articles

Understanding dilution effects on particle-containing pesticide droplets deposition on rice leaf via developing CFD-VOF-DPM model.

Pesticide dilution is one of the essential aspects of plant protection. However, the effect of dilution on the deposition characteristics of pesticide droplets containing particulate additives on crop leaf surfaces remains unclear and warrants further research. Herein, a validated computational fluid dynamics (CFD)-volume of fluid (VOF)-discrete phase model (DPM) numerical model was developed to analyze the influence of particle content on the deposition behavior of droplets on the leaf surface comparatively, taking into account the particle content of different diluted thifluzamide solutions. Additionally, the study aimed to analyze further the kinetic behavior of pesticide droplets landing on rice leaves across different dilution conditions. Pesticide droplets diluted 100-fold had a lower retraction rate during spreading than particle-free droplets, so the solution is more easily deposited in the leaves. Moreover, the low dilution (high concentration) increased the critical adhesion rate between droplets and rice leaves, inhibiting the bouncing of droplets on the leaf surface, thus promoting their effective deposition on the surface. In addition, low dilution (high concentration) is not conducive to spreading droplets when the impact velocity is high, and it also results in a large amount of pesticide use. The actual application process can be through understanding the dilution factor of the configured pesticide solution, and reasonable adjustment of the nozzle pressure can effectively improve the utilization rate of pesticides and reduce the pollution brought by pesticides to the environment. These results provide an essential reference for studying pesticide droplet deposition characteristics, including rice plant protection and spraying technology. © 2024 Society of Chemical Industry.

Study on droplet deposition characteristics and application of small and medium crown garden plants sprayed by UAV sprayer.

The Unmanned Aerial Vehicle (UAV) sprayer has the advantages of high work efficiency, simple operation, and high safety factor, and has broad application prospects UAV sprayer are widely used in the agricultural field, and the application of UAV sprayer spraying technology in agriculture has provided convenience and increased profits for farmers, and has also become a research hotspot in the field of agriculture. In recent years, although research has been conducted on the feasibility and application effects of UAV sprayer spraying crown shaped plants, there have been no experiments or studies in the field of garden plants. This experiment conducted a droplet deposition experiment of UAV sprayer spraying garden plants, exploring the droplet deposition effect of UAV sprayer in the field of garden plants, and conducting experiments on the influence of spray volume and nozzle type on droplet deposition. The experimental results showed that the canopy performance of small and medium-sized garden plants was better at a flight altitude of 1.5m, a spray volume of 180L/hm2, and a flight speed of 2m/s. Reducing flight altitude, increasing spray volume, and reducing flight speed can improve the distribution of droplets in the canopy. This experiment lays the foundation for the application of UAV sprayer for the prevention and control of pests and diseases in garden plants, as well as for the application of growth regulators, and provides a basis for further innovative research in the field of garden plant application technology.

Variable-rate spray system for unmanned aerial applications using lag compensation algorithm and pulse width modulation spray technology

To ensure that a variable-rate spray (VRS) system can perform unmanned aerial spray in accordance with a prescription map at different flight speeds, we examine in this paper such significant factors as the response time of the VRS system and the pressure fluctuation of the nozzle during the variable-rate spraying process. The VRS system uses a lag compensation algorithm (LCA) to counteract the droplet deposition position lag caused by the system response delay. In addition, pulse width modulated (PWM) solenoid valves are used for controlling the flowrates of the nozzles on the variable-rate spray system, and a mathematical model was constructed for the spray rate (L min-1) and the relative proportion of time (duty cycle) each solenoid valve is open. The pressure drop and solenoid valve response time at different duty cycles (50%~90%) were measured by indoor experiments. Meanwhile, the lag distance (LD), spray accuracy, and droplet deposition characteristics of the VRS system were tested by conducting outdoor experiments at different flight speeds (4m s-1, 5m s-1, 6m s-1). The results show that LCA can effectively reduce the lag distance. The lag distance (LD) values of the VRS system with LCA ranged from -0.27 to 0.78m with an average value of 0.32m, while without LCA, the LD values increased to 3.5~4.3m with an average value of 3.87m. The overall spray position accuracy was in the range of 91.56%~97.32%. Furthermore, the spray coverage and deposition density, determined using water sensitive paper (WSP), were used to evaluate the spray application performance taking into account the spray volume applied. The VRS system can provide the most suitable spray volumes for insecticide and fungicide plant protection products. Based on a prescription map, the optimized VRS system can achieve accurate pesticide spraying as well as desirable spray coverage and deposition density.

Analysis of the research progress on the deposition and drift of spray droplets by plant protection UAVs

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.

Non-uniform droplet deposition on femtosecond laser patterned superhydrophobic/superhydrophilic SERS substrates for high-sensitive detection.

Surface-enhanced Raman scattering (SERS) sensors combined with superhydrophobic/superhydrophilic (SH/SHL) surfaces have shown the ability to detect ultra-low concentrations. In this study, femtosecond laser fabricated hybrid SH/SHL surfaces with designed patterns are successfully applied to improve the SERS performances. The shape of SHL patterns can be regulated to determine the droplet evaporation process and deposition characteristics. The experimental results show that the uneven droplet evaporation along the edges of non-circular SHL patterns facilitates the enrichment of analyte molecules, thereby enhancing the SERS performance. The highly identifiable corners of SHL patterns are beneficial for capturing the enrichment area during Raman tests. The optimized 3-pointed star SH/SHL SERS substrate shows a detection limit concentration as low as 10-15 M by using only 5 µL R6G solutions, corresponding to an enhancement factor of 9.73 × 1011. Meanwhile, a relative standard deviation of 8.20% can be achieved at a concentration of 10-7 M. The research results suggest that the SH/SHL surfaces with designed patterns could be a practical approach in ultratrace molecular detections.

Droplet Penetration Model Based on Canopy Porosity for Spraying Applications

Analysing the penetration and droplet deposition characteristics in the canopy of fruit trees is critical for optimising the operational parameters of air-assisted spraying equipment, achieving precise application of chemicals, and improving the effectiveness of fruit tree pest and disease control. We used a mobile LIDAR system to detect the tree canopy characteristics and optical porosity and conduct wind tunnel experiments to investigate the interaction between the tree canopy, the airflow field, and the droplet penetration ratio in the canopy of fruit trees. The results show that the relative wind velocity decreases rapidly during canopy penetration, and that the minimum value occurs at the back of the canopy. The smaller the optical porosity, the greater the reduction in wind velocity is. The quadratic exponential regression model had the highest coefficient of determination (R2) (0.9672) and the lowest root mean square error (RMSE) (5.56%). This paper provides information on optimising the spraying parameters, improving the pesticide utilisation rate, and selecting the optimum spraying conditions and application parameters.

Study on Spray Deposition and Drift Characteristics of UAV Agricultural Sprayer for Application of Insecticide in Redgram Crop (Cajanus cajan L. Millsp.)

Insecticide applications are typically being carried out with traditional manual spraying equipment in redgram, which leads to inadequate control of insects due to higher crop height. The modern deployment of tractor-drawn spray machines causes serious damage to the crop. In this connection, unmanned aerial vehicle (UAV) spray technology has great potential for precise insecticide application in redgram crops. One of the important machine parameters influencing droplet deposition and drift characteristics in UAV sprayers is downwash airflow generated by a multi-rotor propeller. A field experiment was carried out at the redgram research field (N11.01, E76.92), Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, during 2021–2022 to study the spray drift and deposition characteristics of an autonomous UAV sprayer. The Imidacloprid (a.i. 17.8SL) insecticide mixed with water in a ratio of 1 mL per liter was sprayed with a UAV sprayer. Water-sensitive paper samples were kept at upper, middle, and bottom positions on the leaves, and data were analyzed for the spray droplet size, deposition rate, droplet density, and area coverage both in target and non-target areas using Spray Deposit Scanner software. UAV spray droplet deposition rate (2.93 ± 0.17, 2.01 ± 0.08, and 2.21 ± 0.162.38 μL cm−2), droplet density (47 ± 4.04, 53 ± 3.61, and 52 ± 8.74 droplets cm−2), and area coverage (15.72 ± 0.39, 16.60 ± 0.71, and 14.99 ± 0.39%) were highest in the upper layer as compared to the middle layer (droplet deposition rate: 1.21 ± 0.08, 1.07 ± 0.03, and 0.77 ± 0.02 μL cm−2; droplet density: 42 ± 2.52, 43 ± 8.50, and 38 ± 2.52 droplets cm−2; area coverage: 10.95 ± 0.81, 11.22 ± 0.56, and 8.57 ± 0.44%) and bottom layer (droplet deposition rate: 0.41 ± 0.06, 0.35 ± 0.03, and 0.33 ± 0.03 μL cm−2; droplet density: 22 ± 4.36, 17 ± 3.51, and 19 ± 4.51 droplets cm−2; area coverage: 2.78 ± 0.29, 2.95 ± 0.45, and 2.46 ± 0.20%, respectively). In the spray drift test, there was a higher droplet deposition rate (1.63 ± 0.09, 1.93 ± 0.05, and 1.82 ± 0.06 μL cm−2), area coverage (14.40 ± 0.07, 17.54 ± 0.36, and 16.42 ± 0.30%), and droplet density (46 ± 3.61, 54 ± 2.08, and 45 ± 3.21 No’s cm−2) in the target area as compared to the non-target area (droplet deposition rate: 0.88 ± 0.02, 0.46 ± 0.03, 0.22 ± 0.05, and 0.00 μL cm−2; droplet density: 23 ± 1.53, 11 ± 2.08, 6 ± 1.53, and 0.00 droplets cm−2; area coverage: 7.58 ± 0.34, 4.41 ± 0.19, 2.16 ± 0.05, and 0.00%, respectively), which may have been due to the downwash airflow produced by the multi-rotor propeller of the UAV sprayer. Finally, the UAV-based spraying technology results showed that the downwash air produced by the six-rotor propeller improved the penetrability of insecticide to crop leaves and led to a higher droplet deposition rate, droplet density, area coverage, and droplet penetrability on the upper layer, middle layer, and bottom layer of the plants.

Experimental Study of the Droplet Deposition Characteristics on an Unmanned Aerial Vehicle Platform under Wind Tunnel Conditions

Unmanned aerial vehicles (UAVs) are widely used in field pesticide spray operations due to their wide applicability and high operational efficiency. However, their high spray height and fine pesticide droplets lead to a greater risk of drift and likely different droplet deposition outcomes compared to the expectation. So far, most of the previous studies have used direct field methods on UAVs’ droplet deposition characteristics and there have been few carried out in wind tunnels. Thus, in this paper, a simulated UAV platform equipped with TeeJet 80-015 VP fan nozzles was utilized to study the droplet deposition characteristics in a wind tunnel. The droplet deposition amount and drift potential reduction percentage (DPRP) under different spray parameters were obtained. The results showed that when the rotor was open, the deposition amount in the target area increased by 2.6 times and the drift deposition amount decreased by 7.3 times when spraying tap water at 3 m/s wind speed and 3 bar pressure. Faster wind speeds led to greater drift deposition amounts and a lower DPRP, but higher pressures resulted in greater drift deposition amounts and a larger DPRP. The 30 g/L PEG-20000 solution has a higher droplet size and smaller relative droplet spectrum width RS, resulting in the deposition amount in the target area increasing by 9.13% on average and the drift amount decreasing by 24.7% on average, and it can be used as an anti-drift additive when needed. The research results can provide reference and technical support for UAV wind tunnel tests and field operation specifications.

Computational fluid dynamics simulation experimental verification and analysis of droplets deposition behaviour on vibrating pear leaves

BackgroundThe interaction between canopy and droplets is very important in the process of crop spraying. During the actual air-assisted application process, air-mist flow inevitably disturbs the leaves before droplets reaching them, which will also affect the final deposition state of the droplets on the leaf. Currently, researches on the interaction between droplets and the target leaf surface mainly focuses on the deposition behaviour on the surface of stationary target leaves rather than the dynamic leaves. Therefore, the deposition characteristics after the collision between the droplets and dynamic leaves are important for practical application and worth further study.ResultsComputational fluid dynamics simulations were performed to characterise the surface roughness, contact angle, and mechanical vibration. The interaction platform between the droplet and the vibrating pear leaf was built for experimental verification under laboratory conditions. The simulation results are in good agreement with the experimental results, which revealed the main reason for the droplet spreading and sliding was the inertial force generated by the relative velocity. It also indicated that the pear leaf vibration can improve the deposition of low-velocity and small droplets, which is different from that of static pear leaves.ConclusionThe deposition effect of droplets in vibrating pear leaves was investigated. This study also provides a simulation method for the collision between a vibrating leaf and moving droplets, and provides reference for the study of droplet deposition characteristics under the vibration of fruit trees.

Droplet deposition characteristics detection method based on deep learning

Accurate acquisition of spraying quality parameters of plant protection Unmanned Aerial Vehicle (UAV) is helpful to analyze the deposition and distribution of pesticides in field crops. It is of great significance for pest control. UAV spray quality detection system was used to collect droplets, the droplet deposition parameters can be detected by processing the droplet images. However, the spots and the adhesion of the droplets led to large data errors. In order to solve this problem, this paper developed a recognition method of adhesive droplets based on Deeplab V3 + deep learning network, and a concave point matching segmentation algorithm based on convolutional neural network was designed to segment adhesion droplets. Used water instead of pesticides to spray to verify the detection effect of the above method. The test results showed that this method was accurate in the identification and extraction of droplets in the detection of droplet coverage. Compared with the droplet coverage measured by Deposit scan, the average relative error is 3.81%. Compared with the manual counting method, the detection error of the droplet deposition density was 3.17%. It was better for the segmentation of adhesion droplets. In terms of droplet size detection, compared with volume middle diameter measured by laser particle sizer, the detection error was 5.48%. This method improves the accuracy of UAV spray quality detection, so as to ensure the correctness of plant protection UAV spraying decisions.

Effects of leaf response velocity on spray deposition with an air-assisted orchard sprayer

The interaction between leaves and airflow has a direct effect on the droplet deposition characteristics of the leaf canopy. In order to make clear the mechanism of droplet deposition in terms of the interaction between the droplets and leaves from the point of the leaf aerodynamic response velocity, the leaf movement under different airflow velocities and the influence of the leaf aerodynamic response on droplet coverage ratio were investigated. The effect of the aerodynamic response velocity of a leaf on the droplet deposition of the leaf surface was investigated. The aerodynamic characteristics of the leaf were analyzed theoretically. Boundary layer theory from fluid mechanics was used to develop a model of the leaf aerodynamic response velocity to nonperiodic excitations based on a convolution integral method. Target leaf aerodynamic velocities were detected using a high-speed camera, and the results indicated that the modeled leaf aerodynamic response velocity matched the measured values. At given conditions of spray liquid and leaf surface texture, the spray test showed that the droplet coverage ratio was influenced by the leaf aerodynamic response velocity, the droplet coverage ratio increased and then decreased with the leaf response velocity. Through analyze four droplets deposition state, the highest droplet deposition ratio and best deposition state on the leaf surface occur when the leaf aerodynamic response velocity was less than 0.14 m/s. According to the analysis of droplet deposition states, the uniformity of the droplet size and quantity distribution of droplets on the leaf surface related to the leaf aerodynamic response velocity. The results can provide a basis for the design and optimization of orchard air sprayers. Keywords: air-assisted spray, leaf wind vibration, leaf aerodynamic response velocity, droplet deposition states, droplet retention, orchard DOI: 10.25165/j.ijabe.20211401.5435 Citation: Li J, Li Z Q, Ma Y K, Cui H J, Yang Z, Lu H Z. Effects of leaf response velocity on spray deposition with an air-assisted orchard sprayer. Int J Agric & Biol Eng, 2021; 14(1): 123–132.

Numerical investigation on the origin of virus-laden droplets in the respiratory tract

There have been over 17 million COVID-19 infections worldwide up to July 31, 2020, but the exact transmission route remains a subject for debate. Virus load in different-sized respiratory droplets is the key to address the above question. Investigation on the droplet deposition characteristics during exhalation inside the respiratory tract will facilitate the understanding of their origin and importance in transmitting the respiratory infection. Based on a realistic respiratory model, this study utilized the computational fluid dynamic (CFD) simulation to investigate the deposition of droplets originating from infection sites like pharynx, larynx and trachea under three flow conditions, namely 30 L/min (representing the normal breathing condition), 60 L/min (speaking) and 180 L/min (coughing). The SST k - ω turbulence model integrated in ANSYS Fluent software was utilized to obtain the flow field inside the respiratory tract by solving the continuity and momentum equations, and the Lagrangian approach was used to calculate droplet motion and deposition with the discrete random walk model to account for the turbulence fluctuation effect. Evaporation of droplets was not considered inside the saturated respiratory tract. Droplet diameter, flow rate of the exhaling air, and complexity of the respiratory tract geometry are the most important factors in determining the deposition pattern of respiratory droplets. It is revealed that the largest droplet that originates from the joint of pharynx and larynx and is able to escape out of the respiratory tract is about 20 µm (30 L/min) or 10 µm (60–180 L/min) in diameter; the so-called cut-off sizes for vocal cord and trachea originated droplets are 7 µm (30 L/min), 5 µm (60 L/min) or 3 µm (180 L/min). Larynx and joint of larynx and pharynx are the most important deposition sites due to their complexity in geometry and the existence of the laryngeal jet, whose velocity is up to 102 m/s during coughing and 32 m/s during speaking; the nasal cavity is also effective in trapping relatively small droplets as the airflow has a sudden change in direction before entering the oral cavity. Under the investigated speaking scenario (60 L/min), the escape rate of 1 µm droplets is around 50%, and the maximum escape rates of 5 and 10 µm droplets are respectively 13.1% and 1.3% (originating from the joint of pharynx and larynx). Although large droplets up to several hundred micrometers can be produced inside the oral cavity due to the atomization mechanism, they seldom carry pathogen. Thus, for COVID-19 patents in the early stage of infection who show upper respiratory symptoms, the cut-off size of virus-laden droplets released into the environment is about 20 µm; with the shifting of infection to the lower respiratory tract in the later stage, the cut-off size decreases to 7 µm. Respiratory droplets evaporate immediately after escaping into the indoor environments and shrink to about one third of their initial size, so airborne route is speculated to be important in the transmission of COVID-19. Further investigations considering realistic flow conditions together with droplet sampling experiments on human volunteers are necessary to confirm these cut-off sizes.

Analysis of Oil Droplet Deposition Characteristics and Determination of Impact State Criterion in Aero-Engine Bearing Chamber

The research of oil/air two-phase flow and heat transfer is the fundamental work of the design of lubrication and heat transfer in aero-engine bearing chamber. The determination of impact state criterion of the moving oil droplets with the wall and the analysis of oil droplet deposition characteristics are important components. In this paper, the numerical analysis model of the impact between the moving oil droplet and the wall is established by using the finite volume method, and the simulation of oil droplet impingement on the wall is carried out. Then the effects of oil droplet diameter, impact velocity, and incident angle on the characteristic parameters of impact state are discussed. The characteristic parameters include the maximum spreading length, the maximum spreading width, and the number of splashing oil droplets. Lastly the calculation results are verified through comparing with the experimental results in the literature. The results show as follows: (1) The maximum spreading width of oil droplet firstly increases and then slows down with the incident angle and the oil droplet diameter increasing; (2) when the oil droplet diameter becomes small, the influence of the incident angle on the maximum spreading length of oil droplet is obvious and vice versa; (3) with the impact velocity and diameter of oil droplet increasing, the maximum spreading width of oil droplet increases firstly and then slows down, and the maximum spreading length increased gradually; (4) the number of splashing oil droplets increases with the incident angle and impact velocity increasing; and (5) compared with the experimental data in literature, the critical dimensionless splashing coefficient K c proposed in this paper can better distinguish the impact state of oil droplet.

Field based evaluation of Han-Mercury1 UAV sprayer: droplet deposition characteristics at various canopy heights of soybean crop

Field based evaluation of Han-Mercury1 UAV sprayer: droplet deposition characteristics at various canopy heights of soybean crop

Field based evaluation of Han-Mercury1 UAV sprayer: droplet deposition characteristics at various canopy heights of soybean crop

Modern agriculture is precision oriented and more focused on efficient usage of plant protection unmanned aerial vehicles (PPUAVs) for spray operations. It is of great importance on many fundamenta...

Influence of UAV flight speed on droplet deposition characteristics with the application of infrared thermal imaging

A plant protection unmanned aerial vehicle (UAV) applied for spraying pesticide has the advantages of low cost, high efficiency and environmental protection. However, the complex and changeable farmland environment is not conductive to perform spray test effectively. It is therefore necessary to carry out spray test under controlled conditions. The current study aimed to illuminate the variation law of droplet deposition characteristics under different UAV flight speeds, and to verify the feasibility for applying infrared thermal imaging in detection of droplet deposition effects. A UAV simulation platform with an airborne spray system was established and an analysis program Droplet Analysis for dealing with water-sensitive paper was developed. The results showed that, when the flight speed was set at 0.3 m/s, 0.5 m/s, 0.7 m/s, 0.9 m/s and 1 m/s, respectively, the droplet deposition density, droplet deposition coverage and arithmetic mean of droplet size D0 decreased as the UAV flight speed increased. On the contrary, the droplet diameter variation coefficient CV increased with the increase of UAV flight speed, resulting in the worse uniformity of sprayed droplet distribution as well. The results can provide a theoretical support for optimizing the spraying parameters of plant protection UAV, and demonstrate the practicability of infrared thermal imaging in evaluating the droplet deposition in the field of aerial spraying. Keywords: spray test, UAV flight speed, droplet deposition characteristics, droplet analysis, image processing, infrared thermal imaging DOI: 10.25165/j.ijabe.20191203.4868 Citation: Lv M Q, Xiao S P, Tang Y, He Y. Influence of UAV flight speed on droplet deposition characteristics with the application of infrared thermal imaging. Int J Agric & Biol Eng, 2019; 12(3): 10–17.

Influence of UAV flight speed on droplet deposition characteristics with the application of infrared thermal imaging

Influence of UAV flight speed on droplet deposition characteristics with the application of infrared thermal imaging

Dynamic characteristics of charged droplets in an electrostatic spraying process with twin capillaries

Abstract The experimental and simulated investigations on electrostatic spraying with twin capillaries are carried out. The starting electric voltage required for the cone-jet and the deposition characteristics of the droplets are measured. The whole spraying process, which includes jet and droplet motions, is simulated and the simulated results on the motions of jet and droplet are basically consistent with the experiments. According to the simulated results, the contributions of various electric forces to droplet movement are quantitatively analyzed and the droplet dynamic characteristics, especially the interaction mechanism between two sprays, are revealed. The test results on the droplet deposition characteristics partially support the simulated results on the droplet motion. The present work is useful for a better understanding on the interaction between sprays in double or multi-capillary system.

Droplet deposition and spatial drift distribution characteristics of aerial spraying based on the determination of effective swath

Abstract: In order to accurately explore the droplets distribution characteristics on the ground and space during the aerial spray process, a single-pass application test based on the determination of effective swath by a Bell206L4 helicopter was carried out. The accurate effective swath width of the helicopter spray operation was obtained, and the cumulative and spatial drift characteristics of droplet deposition when the helicopter used different aerial nozzles under natural environment were systematically analyzed. The results showed that the average effective swath width of three different types of nozzle were 25.3 m (CP02), 29.7 m (CP03) and 29.3 m (CP04) with an average flight altitude of 11 m and velocity of 17 m/s. The average deposition volume in the effective swath area of each sampling line was in the range of 1.208-2.735 ?L/cm 2 . Most of the droplets in each application were concentrated near the route and the adjacent locations of the effective swath area. In addition, the droplets with small size were trend to drift, and the increased nozzle orifice size was beneficial to reduce drift. In terms of spatial drift distribution, small-sized droplets usually gathered in the upper space, larger-sized droplets were easy to gather in the middle space, and the medium-sized droplets were trend to gather in the lower space. The research results were helpful to optimize the spray plan and provide reference for precision aerial application. Keywords: aerial spray, droplet deposition, spatial drift, effective swath, helicopter, precision agricultural DOI: 10.33440/j.ijpaa.20210401.145 Citation: Yao W X, Guo S, Yu F H, Du W, Meng Y H, Wang J, Chen P C, et al. Droplet deposition and spatial drift distribution characteristics of aerial spraying based on the determination of effective swath. Int J Precis Agric Aviat, 2021; 4(1): 36–43.

CFD Simulation of Low-attitude Droplets Deposition Characteristics for UAV based on Multi-feature Fusion

The movement and deposition patterns of pesticide liquids in complex airflow field were difficult to determine, and thus led to some problems such as low utilization efficiency of pesticide and reduce quality of agricultural products. By using CFD technology, simulation test was carried out to study the droplet deposition characteristics within range of -1.5m to 4m in the downwind direction of UAV based on multi-feature fusion. The simulation boundary conditions and simulation parameters of 3-dimentional air field space were defined according to the spraying parameters measured from the UAV. The results showed that: droplet deposition was distributed in parabolic form. The deposition of droplets decreased with the increase of airflow velocity and spray height, and deposits scale was gradually moved away from the nozzle. When airflow velocity was greater than 3m/s, or spray height was more than 1.3m, it was not suitable for spraying. The deposition increased with the increase of droplet size, and deposits scale reduced. The change of spray angle caused a certain influence on distribution of droplet deposition, and it was a main factor that affects deposition characteristic. The result would provide a theoretical reference for spraying parameters determination and operating conditions selection.