Air-assisted Sprayer Research Articles

Effect of Leaf Removal and Insecticide Applications on Population Densities of Leafhoppers and Mites Associated with Grapevines.

In this study, we tested the effects of mechanical leaf removal, insecticide application, and their interaction on leafhoppers and phytophagous and predatory mites occurring in two vineyards over three growing seasons. Leaf removal was performed in the fruit zone using a two-head pulsed air leaf remover, while insecticides were applied with a tunnel air-assisted sprayer at the maximum dose/ha recommended on the product label. Results demonstrated the efficacy of insecticide application in reducing the population densities of leafhoppers but also their detrimental effects on predatory mites. In a number of case studies, leaf removal reduced leafhopper and predatory mite densities. In one vineyard, phytophagous mite populations increased some weeks after leaf removal and insecticide application, highlighting the need to carefully consider the potential impact of vineyard management practices on non-target arthropods in the IPM framework.

Design and experimental assessment of a field-spraying system with nozzles employing reciprocating up-and-down movements.

Proper dense planting pattern can improve rice yield. For an ordinary boom sprayer, it is still difficult for the droplets to penetrate the dense rice canopy even if an auxiliary airflow is used, especially in the middle and late growth stages. The deposits of droplets at the bottom of the rice plants are typically small. In this study, a spraying system was designed with nozzles creating reciprocating movements into the middle and bottom of the rice canopy. An air pump provided power to push the nozzles up and down. A time relay and a solenoid valve were used to control the cycle and stroke of the reciprocating movement. At different growth stages of rice, comparative tests were conducted between the air-assisted spraying pattern (without reciprocating movement of nozzles) and the reciprocating movement spraying pattern (without auxiliary airflow). The results showed that for the reciprocating movement spraying pattern, the droplet number densities in the middle and bottom of the rice in the late growth stages increased from 78 to 124/cm2 and from 19 to 121/cm2 , respectively, and the coverage rates increased from 13.34% to 24.26% and from 3.61% to 21.21%, respectively. The droplet depositions increased from 0.603 to 1.139 mg cm-2 and from 0.095 to 1.001 mg cm-2 , respectively. This spraying pattern can increase droplet deposits at the middle and bottom of the crop and improve uniformity. © 2023 Society of Chemical Industry.

Research on decoupled air speed and air volume adjustment methods for air-assisted spraying in orchards.

Different fruit tree canopies have different requirements for air speed and air volume. Due to the strong relationship between air speed and air volume, the decoupled control of air speed and air volume cannot be achieved using the existing sprayers. In this study, an innovative air-assisted sprayer that supports the independent adjustment of fan speed (0-2940 r/min) and air outlet area (1022.05-2248.51 cm2) is developed, and the maximum air speed and air volume of the sprayer outlet are 45.98 m/s and 37239.94 m3/h, respectively. An independent adjustment test of the fan speed and air outlet area was carried out. The results indicated that the fan speed and air outlet area have opposing adjustment effects on air speed and air volume; decoupled control of the outlet air speed and air volume can thus be achieved through combined control of the fan speed and air outlet area. A test was carried out on combined fan speed and air outlet area control. Two decoupled air speed and air volume adjustment models were established, one with a constant air speed and variable air volume and the other with a constant air volume and variable air speed. The test results show that the air volume adjustment model with constant air speed had a maximum mean error of 1.13%, and the air speed adjustment model with constant air volume had a maximum mean error of 1.67%. The results will provide theoretical and methodological support for the development of airflow adjustment systems for orchard air-assisted sprayer.

Fruit Powder Analysis Using Machine Learning Based on Color and FTIR-ATR Spectroscopy—Case Study: Blackcurrant Powders

Fruits represent a valuable source of bioactivity, vitamins, minerals and antioxidants. They are often used in research due to their potential to extend sustainability and edibility. In this research, the currants were used to obtain currant powders by dehumidified air-assisted spray drying. In the research analysis of currant powders, advanced machine learning techniques were used in combination with Lab color space model analysis and Fourier transform infrared spectroscopy (FTIR). The aim of this project was to provide authentic information about the qualities of currant powders, taking into account their type and carrier content. In addition, the machine learning models were developed to support the recognition of individual blackcurrant powder samples based on Lab color. These results were compared using their physical properties and FTIR spectroscopy to determine the homogeneity of these powders; this will help reduce operating and energy costs while also increasing the production rate, and even the possibility of improving the available drying system.

Development and assessment of a novel servo-controlled spraying system for real time adjustment of the orientation angle of the nozzles of a boom sprayer.

Pesticide spray drift, which is the movement of pesticide by wind to any location other than the intended area, is hazardous to human, animal, food safety and environmental health. It is not possible to completely eliminate spray drift during spraying with field crop sprayers, but spray drift can be reduced by developing new technologies. The most common methods to reduce spray drift are carrying the droplets to the target with air-assisted spraying, electrostatic spraying, preferring air induction nozzles and boom shields. With these methods, it is not possible to make a change on the sprayer depending on the wind intensity during spraying. In this study, a novel servo-controlled spraying system was designed and developed to change the nozzle orientation angle in the reverse direction of the wind current to reduce the ground spray drift in real time and automatically in a wind tunnel. The displacement in the spray pattern (Dc ) was used as a ground drift indicator for each nozzle to evaluate the spray drift. The developed system, operated by LabVIEW software, calculated different nozzle orientation angles depending on nozzle types, wind velocities and spraying pressures. Orientation angles calculated for different test conditions achieved in reduction were up to 49.01% for XR11002 nozzle, 32.82% for AIXR11002 nozzle and 32.31% for TTJ6011002 nozzle at 400 kPa spray pressure and 2.5 m s-1 wind velocity. The developed system, which has a self-decision mechanism, calculated the nozzle orientation angle instantaneously according to the wind velocity. It has been observed that the adjustable spraying nozzle system, sprayed with high precision towards the wind in the wind tunnel, and the developed system have advantages compared to conventional spraying systems. This article is protected by copyright. All rights reserved.

Effect of injection strategy on an air-assisted direct injection aviation kerosene two-stroke engine

In small aviation piston engines, the atomization and combustion of aviation kerosene have attracted much attention. Due to the low volatility and high viscosity of aviation kerosene, high-pressure injection or air-assisted injection is used to improve the fuel atomization quality. Considering the weight, cost and power consumption, air-assisted injection is more appropriate for compact, small aviation piston engines. In the paper, computational fluid dynamics (CFD) software was used to simulate the air-assisted spray and spark ignition combustion of aviation kerosene in a heavy-fuel direct injection spark ignition (DISI) two-stroke engine based on air-assisted direct injection (AADI) technology. The effects of injection pressure, single and double injection on formation and combustion characteristics of the aviation kerosene/air mixture were analyzed. The results show that increasing the air-assisted injection pressure can promote air flow in the cylinder and accelerate fuel evaporation, but also increase the film mass on the combustion chamber wall. When single injection is employed, high combustion pressure and temperature are generated, and the tendency to knocking combustion is greater. The use of double injection can effectively achieve fuel stratification and reduce knock tendency. With the delay of the second mixture injection timing, the peak combustion pressure is reduced, the heat release rate is slowed down, and the knock tendency is reduced correspondingly.

Effect of airflow angle on abaxial surface deposition in air-assisted spraying.

Air-assisted sprayers are widely used in orchards for pest and disease control. However, air-assisted spray deposition on the abaxial surface of leaves is often limited. In this study, a method to achieve satisfactory spray deposition on the abaxial leaf surface and an assessment of factors that affect abaxial surface deposition were investigated. The effects of leaf angle, wind speed, platform velocity, and nozzle type were assessed. Abaxial surface coverage was significantly affected by leaf angle, wind speed, and nozzle type, of which the leaf angle had the strongest impact. The leaf angle largely determines the abaxial surface area exposed to the wind field. When the abaxial surface is situated leeward, deposition of droplets on the abaxial surface is difficult. Therefore, to improve abaxial surface exposure for field application, the exposure probability of the abaxial surface at different angles between the leaf and the airflow (α) was examined. The relationship was well represented by a logistic growth curve. The exposure probability exceeded 95% when the α value was greater than 5°. The latter finding was verified by conducting a field application in which the deposition efficiency on the abaxial surface (DEAS) was calculated. Adjustment of the airflow angle based on the theoretical value achieved DEAS of 49.9% and 109.3% in the middle and upper layers of the canopy, respectively, whereas the DEAS was less than 30% if the airflow angle was not adjusted. This is caused by the difference in the exposure probability of the back of the leaf. The results provide a reference for adjustment of the wind field of air-assisted sprayers in field applications.

Visualization of Lidar-Based 3D Droplet Distribution Detection for Air-Assisted Spraying

Air-assisted spraying is a commonly used spraying method for orchard plant protection operations. However, its spraying parameters have complex effects on droplet distribution. The lack of large-scale 3D droplet density distribution measurement methods of equipment has limited the optimization of spraying parameters. Therefore, there is a need to develop a method that can quickly obtain 3D droplet distribution. In this study, a 2D LiDAR was used to quickly scan moving droplets in the air, and a test method that can obtain the visualization of 3D droplet distribution was constructed by using the traveling mode of the machine perpendicular to the scanning plane. The 3D droplet distribution at different positions of the nozzle installed in the air-assisted system was tested at different fan rotation speeds, and the methods for signal processing, point cloud noise reduction, and point cloud division for 2D LiDAR were developed. The results showed that the LiDAR-based method for detecting 3D droplet distribution is feasible, fast, and environmentally friendly.

Research Status, Methods and Prospects of Air-Assisted Spray Technology

Air-assisted boom sprayer is proven to be one of the best pesticide application methods to achieve uniform deposition of droplets in the canopy and improve the effective utilization of pesticides. However, the air flow velocity, air flow volume and air flow direction of the orchard sprayer should match the characteristic parameters of the target canopy, equipment spraying parameters and meteorological conditions so as to improve the spraying quality and reduce environmental pollution. This paper elaborates on the research status of air-assisted field sprayers and orchard sprayers, summarizes the research methods of air-assisted sprayers in four aspects, including experimental verification, theoretical analysis, simulation and structural optimization, and clarifies the advantages and disadvantages of these methods. It also presents two future research and development trends, including the intelligent, precise dynamic regulation of air flow velocity, air flow volume and air flow direction and the instant feedback of spraying quality, hoping to provide a reference for the research of air-assisted spray technology and equipment.

Computational model of pesticide deposition distribution on canopies for air-assisted spraying.

The deposited pesticide distribution in fruit tree canopies is crucial for evaluating the efficacy of air-assisted spraying in orchards. Most studies have determined the impact of pesticide application on pesticide deposition on canopies without a quantitative computational model. In this study, an air-assisted orchard sprayer with airflow control was used to perform spraying experiments on artificial and peach trees. In the spraying experiment on an artificial tree, a canopy with leaf areas ranging from 2.54~5.08 m2 was found to require an effective air speed of 18.12~37.05 m/s. The canopy leaf area, air speed at the sprayer fan outlet and spray distance were used as test factors in a three-factor five-level quadratic general rotational orthogonal test to develop a computational model for pesticide deposition at the inner, outer and middle regions of a fruit tree canopy with R 2 values of 0.9042, 0.8575 and 0.8199, respectively. A significance analysis was used to rank the influencing factors for the deposited pesticide distribution in decreasing order of significance as follows: the spray distance, leaf area and air speed for the inner region of the canopy, followed by the spray distance, air speed and leaf area for the middle and outer regions of the canopy. The results of the verification test conducted in a peach orchard showed that the computational errors of the pesticide deposition model for the inner, middle and outer regions of the canopy were 32.62%, 22.38% and 23.26%, respectively. The results provide support for evaluating the efficacy of an air-assisted orchard sprayer and optimizing the sprayer parameters.

Effects of sprayer speed, spray distance, and nozzle arrangement angle on low-flow air-assisted spray deposition.

Air-assisted spraying technology is widely used in orchard sprayers to disturb canopy leaves and force droplets into the plant canopy to reduce droplet drift and increase spray penetration. A low-flow air-assisted sprayer was developed based on a self-designed air-assisted nozzle. The effects of the sprayer speed, spray distance, and nozzle arrangement angle on the deposit coverage, spray penetration, and deposit distribution were investigated in a vineyard by means of orthogonal tests. The optimal working conditions for the low-flow air-assisted sprayer working in the vineyard were determined as a sprayer speed of 0.65m/s, a spray distance of 0.9m, and a nozzle arrangement angle of 20°. The deposit coverages of the proximal canopy and intermediate canopy were 23.67% and 14.52%, respectively. The spray penetration was 0.3574. The variation coefficients of the deposit coverage of the proximal canopy and intermediate canopy, which indicate the uniformity of the deposition distribution, were 8.56% and 12.33%, respectively.

Optimization of Diversion Device and Experiment on Air-assisted Sprayers in Orchards

In order to improve the velocity distribution of the airflow field generated by the air-assisted sprayer in the orchard, a flow field distribution model of the sprayer air delivery system based on CFD simulation is designed. The airflow field distribution of the air-assisted operation is obtained through FLUENT simulation. The calculation domain includes the internal flow field and external flow field of the fan. The simulation result guides the optimal installation angle of the flow guide device. The installation angle of the upper deflector is 50°, and the installation angle of the lower deflector is 25°, so that the airflow generated by the air-assisted sprayer is mainly concentrated at a height of 0.7–3 m when it reaches the pear tree canopy. The installation angle of the inner deflector 1 and inner deflector 2 is 35°, the installation angles of the inner deflector 3, inner deflector 4, and inner deflector 5 are all 45°, and the average speed is increased by 18.81% in the range of height 1.6–2.4 m. A velocity distribution experiment is designed to measure the airflow velocity to verify the accuracy of the CFD simulation model. The simulation value is basically consistent with the measured value, which provides guidance for optimizing the parameters of the flow guide device.

Dynamic simulation of fluid-structure interactions between leaves and airflow during air-assisted spraying: A case study of cotton

The airflow of air-assisted spraying can widen droplet transport channel, increase the variable-track motion of droplets, and uniform of droplet deposition in canopy. However, it is still a challenge to analyze the dynamic interaction behavior between leaves and airflow at the canopy leaves scale. Based on Finite Element (FE) and Lattice-Boltzmann (LB) solver, a two-way, Fluid-Structure Interaction method was proposed to analyze the aerodynamics of leaves under airflow and flow field distribution in the canopy. First, a virtual, simplified 3D cotton plant was generated based on morphology and growth law. Furthermore, a two-way, Fluid-Structure Interaction model was established by co-simulations with the structurally explicit FE solver and LB solver. Finally, the accuracy of the numerical simulations was verified by indoor experiment tests from the two aspects of fluid domain and solid domain. The verification results in the fluid domain showed that mean absolute error of prediction (MAEP) and normalized mean absolute error (NMAE) between simulated and measured values were 0.6317 and 11.38%, respectively. The solid domain verification showed that the maximum value of NMAE between simulated and experimental changes of leaf inclination angle were 21.46%, indicating that the numerical model can accurately simulate the deformation of the cotton leaves. The leaves in flow field reached dynamic stability after 0.4s when the airflow with speed 10 m/s blowing to the canopy. The simulation results can be used to optimize the operating parameters before air-assisted spraying.

Time-resolved low-pressure air-assisted spray performance and unsteadiness evaluation

The main advantages of air-assisted spray are its high-quality atomization at low injection pressures and insensitivity to the viscosity of atomized liquid. In this study, the droplet size and velocity of a low-pressure intermittent air-assisted spray were studied by using phase Doppler anemometry, and the effects of liquid fuel injection duration on time-resolved spray microscopic characteristics and spray unsteadiness were analyzed. Droplet size-velocity joint probability density functions were employed to characterize the droplet diameter-velocity distribution as well as the probability range. A comparison of the droplet Weber number with an empirical critical value indicates that atomized droplets hardly undergo secondary shear breakup. Based on the ideal spray theory of Edwards and Marx, an improved algorithm is proposed with the concept of iterative rejection of inter-particle arrival times to quantify the unsteadiness of air-assisted sprays by eliminating the dependence of the calculation results on droplet sampling data. The results show that intermittent air-assisted spray is an inherently unsteady process that can be influenced by fuel injection duration and spatial location, while independent of the droplet size. In addition, the spray unsteadiness exhibits noteworthy variations at different spray stages segmented by droplet velocity vs time. The relation between the potential internal gas–liquid two-phase status determined by fuel injection duration and the spray performance is elaborated.

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.

Factors Affecting Droplet Loss behind Canopies with Air-Assisted Sprayers Used for Fruit Trees

Air-assisted sprayers are widely employed in orchards, but inappropriate spray parameters can lead to large droplet losses, pesticide waste, and environmental pollution. To investigate the factors affecting the droplet loss of an air-assisted sprayer behind canopies, a two-factor, five-level full experiment was conducted in an actual orchard, where the two factors were the power gradient and foliage area volume density (FAVD). In addition, the location of the sampling point was also considered in the data analysis, including horizontal distance, forward distance, and height. The results show that all factors significantly affected droplet coverage (p-value < 0.01). The droplet coverage showed an increase and then a decrease with an increasing power gradient, and the maximum coverage was measured at power gradient P3 (forward speed: 0.49 m/s, spray pressure: 0.30 MPa, and spray flow rate: 7.13 L/min) or P4 (forward speed: 0.58 m/s, spray pressure: 0.35 MPa, and spray flow rate: 8.44 L/min). The effect of FAVD on droplet coverage had obvious regularity, and this regularity did not change with the power gradient. At different positions behind canopies, the droplet coverage had great differences. The droplet coverage gradually decreases with increasing horizontal distance and height, while increasing with forward distance. This study provides a reference for the air-assisted sprayers to reduce droplet loss, and data support for subsequent research on precision spraying based on FAVD.

Wetting and deposition characteristics of air-assisted spray droplet on large broad-leaved crop canopy.

Precision and efficient pesticide spraying is an important part of precision agriculture, banana is a large broad-leaved plant, with pests and diseases, has a high demand for spraying and pest control. The purpose of this study was to clarify the wettability of different pesticides on the banana leaf surface, and the effects of nozzle type and working parameters on the deposition distribution performance under air-assisted spray conditions. The wettability test results of different pesticides on banana leaf surfaces showed that the wettability of the adaxial side was always stronger than that of the abaxial side, the smaller the surface tension of the droplets, the better the wettability on the surface. The spray experiment was carried out on the previously developed air-assisted sprayer with the latest developed intelligent variable spray control system. Three types of nozzles were used to spray with different combinations of working parameters. The deposition distribution performance on the banana leaf surface was obtained by image processing using a self-compiled program. The experimental results show that the nozzle type, wind speed, and spray pressure have significant effects on the deposition distribution performance. Through the study of the interaction and coupling effect of nozzle type and working parameters on the spray droplet deposition distribution on both sides of banana leaves, the results show that under the conditions of hollow cone nozzle, 0.5Mpa spray pressure and 3-5m/s wind speed, the spray coverage and droplet density are in the optimal state. This is mainly due to the low spray pressure and/or wind speed is not enough to make the banana leaves vibrate and improve the performance of pesticide deposition. excessive spray pressure and/or wind speed will cause large deformation of banana leaves and make them airfoil stable, which reduces the surface deposition performance. It is of great significance for promoting sustainable and intelligent phytoprotection.

Evaluation of the Wind Field and Deposition Effect of a Novel Air-Assisted Strawberry Sprayer

Strawberry is a widely cultivated cash crop in China. In order to control pests and diseases on strawberries, there must be sufficient deposits on the abaxial surfaces of the leaves. Air-assisted technology can effectively increase the deposition on the abaxial surfaces of the leaves; however, most air-assisted equipment is not suitable for application due to the pattern of strawberry planting. Therefore, a novel air-assisted strawberry sprayer was developed, the static and dynamic wind fields were measured using a 3D anemometer, and the effectiveness of the application at different spray angles and wind speeds was evaluated. In addition, a comparison of the deposition effect in the strawberry canopy between the air-assisted strawberry sprayer, knapsack sprayer, and spray gun was conducted. The results showed that in the static wind field test, a difference between the center and edge wind fields was obtained, which was correlated with the distance and the outlet wind speed. In the dynamic wind field test, the wind field was found to be rolling backward during the movement, and an inward vortex was obtained. In the field, the data showed that a spray angle of 30° and a wind speed of 16 m·s−1 had the best deposition on the abaxial surface, with a coverage of 36.5% and 38.3% in the upper canopy and 6.2% and 7.9% in the lower canopy, respectively. Moreover, the air-assisted strawberry sprayer was found to have a higher deposition efficiency on abaxial surfaces than the knapsack sprayer and spray gun at a lower spray volume, the values of which in the upper and lower canopies were 42.8% and 29.7%, respectively. In conclusion, the air-assisted strawberry sprayer has the potential for the crop protection of greenhouse strawberries, and more evaluations are needed to improve the sprayer in the future.

Simple decision-making model for orchard air-assisted spraying airflow

Airflow speed is one of the three factors of air-assisted spraying. Optimizing the matching model between airflow speed and target canopy characteristics is an effective way to improve the orchard precision spraying technology, as airflow can significantly affect droplet deposition and drift loss. A simple model of airflow speed was established in this study. First, air-assisted spraying experiments were carried out on a standard simulation canopy to study the airflow speed depended on canopy width, leaf area index, and porosity rate. Second, determined by Ribbon Method and verified by droplet drift data, the airflow speed through the canopy was between 0.5 m/s and 0.7 m/s. Third, multiple tests were carried out under standard simulation canopy with different characteristics, and the airflow speed model was established ultimately: with a fixed leaf area index (LAI), the relationship between canopy upwind boundary airflow speed and canopy width satisfied the exponential model (y=aebx), and the coefficients a and b are well related to the density of branches and leaves in the canopy. When LAI=3.456, y=2.036e1.5887x, R2=0.994; LAI=1.728, y=1.639e1.445x, R2=0.972. Orchard growers can acquire needed airflow speed through this simple model, it is quick and precise and appropriate to most growth periods of a variety of fruit trees, such as apples, pears, and vines. Keywords: airflow speed, canopy width, porosity rate, LAI, air-assisted spraying DOI: 10.25165/j.ijabe.20231602.6849 Citation: Wang X, Feng Y R, Fu W, Qi J T, Song J L. Simple decision-making model for orchard air-assisted spraying airflow. Int J Agric & Biol Eng, 2023; 16(2): 23-29.

CFD Simulation of Circulating-Airflow Distribution Inside Canopy From Novel Air-Assisted Sprayer in Orchard

HIGHLIGHTS A CFD model was developed to simulate airflow movements from circulating air-assisted sprayer. The CFD model can simulate airflow distribution inside the pear canopy with good accuracy. Simulation identifies the preferred parameters for circulating air-assisted spraying. An excessive adjustment of the airflow angle resulted in the formation of an eddy. ABSTRACT. Circulating air-assisted (CAA) spraying involves a negative pressure suction (NPS) created by a fan placed over the top of a canopy to change the airflow direction twice, i.e., first from the outside of the canopy to its inside and then from the bottom up, which can increase the airflow velocity inside the canopy. However, this new pesticide application technology has not been adequately investigated. In particular, the effects of the inlet and outlet airflow parameters of CAA spraying technology on the airflow distribution inside a canopy are yet to be determined. In this study, a computational fluid dynamics (CFD) model is developed and validated to simulate the interactions between the airflow ejected by a CAA sprayer and the canopy of a fruit tree. In the computational domain, the fruit tree is considered a porous medium. The model is validated based on three fruit trees of different sizes, leaf-area densities (LAD). The root mean square error and the mean relative square error are 1.44, 1.43, 2.22 m/s, and 24.9%, 24.7%, and 36.4%, respectively. This suggests that the CFD model can predict the interactions between the airflow field generated by a CAA sprayer and the canopy of a fruit tree. The validated CFD model is employed to analyze the airflow distribution patterns inside a canopy under different combinations of inlet and outlet airflow parameters. A reasonable combination of inlet and airflow parameters is obtained for CAA spraying technology. For example, the suitable outlet airflow velocity, top NPS, and bottom outlet angle for seven-year-old crown pear trees (average height: 2.0 m; average canopy diameter: 1.2 m; average trunk height: 0.62 m; average LAD: 2.96) selected in this study from a farm in southern China are 15 m/s, 200 Pa, and 10°, respectively. The results of this study can facilitate the parametric adjustment of CAA sprayers and enhance plant protection in orchards. Keywords: Circulating air-assisted spraying, Fruit-tree canopy, Inlet and outlet airflow parameters, Simulation.