Research On Parameter Optimization And Intelligent Control Strategy Of Wind Curtain Anti-drift System Based On Bimodal Distributed Drift Deposition Model

China is the largest country for production and consumption of pesticides,and its pesticide consumption has reached 2.5 times the average consumption of the world..Pesticides are an essential part for the prevention of diseases and insect pests and weeds,and they are of great significance to the food production and safety.However,excessive use of pesticides will cause damage to the ecological environment.The anti-drift system of air curtain is an equipment that can effectively reduce the loss of pesticide,thus improving the utilization rate of pesticide.But most of the design of the relevant air curtain system is still in the stage of empirical design,and the relevant theories are not perfect and the complexity of the application environment is less considered.In this paper,the distribution model of droplet drift deposition is established based on the distribution regularities of droplet drift deposition under lateral wind,and then the simulation and prediction of droplet drift deposition are carried out to find the influence of various spray factors on droplet deposition distribution.Fuzzy control strategy is adopted to improve the intelligence level of air curtain system.The main contents of this study are as follows:?1?According to the characteristics of droplet drift deposition distribution,a model of droplet drift deposition distribution based on bimodal distribution was established,and the droplet deposition distribution was described with the characteristic values of the normal probability density function.And the influence of electrostatic spray on the law was investigated and it was found that the charged droplets obtained by electrostatic spray technology were more likely to drift under the influence of airflow stress during the transportation process.The distribution model of droplet drift and deposition based on bimodal distribution and its changing law provide the basic mathematical model and control idea for the follow-up research.?2?The model of droplet drift deposition is established by Monte Carlo method,which can realize the simulation and prediction of droplet falling point and obtain the distribution of droplet drift deposition under the condition of knowing the droplet particle size distribution and cross wind speed.The model is verified by experiments,and the results show that the mean error between the predicted value and the actual value of the model for the general sector sprinkler head is less than 3%.For IDK drift proof sprinkler head series,the mean error between the predicted result and the actual value is no more than 6%.For the electrostatic spray nozzle,although the difference between the predicted value and the actual value of deposition distribution based on monte carlo method is 5%higher than that in the absence of electrostatic field.It can still effectively simulate and predict the deposition motion of charged fog droplets under wind stress.?3?The influence of multi-directional crosswind on droplet deposition distribution was analyzed by experiment and simulation.In order to reduce this effect and improve the effectiveness of the air curtain system,a guide plate based on laval effect and laval nozzle structure is designed to correct the wind direction for a short distance,so that the wind direction of the flow field in the deposition area becomes a positive crosswind and the transverse velocity is 0m/s.The wind direction correction effect of the diversion group was verified by CFD simulation technology and practical experiments.The flow field formed by the similar laval diversion group and the conventional diversion group was compared.The results showed that the flow field obtained by the similar laval diversion group was uniform,and the velocity variation coefficient of the flow field was smaller.?4?Based on the analysis of the model of droplet drift deposition with bimodal distribution,the concentration and long tail of droplet drift deposition distribution are expressed by the bimodal deposition ratio and the tail length.The smaller the values of these two quantities are,the more concentrated the distribution of droplets deposition is,and the shorter the tail deposition length of droplets formed by drift.According to the variation rule of the bimodal deposition ratio and the length of the deposition tail when the relative distance between the air curtain and the sprinkler head is different,the optimal distance interval??₁,?₂+?₂?is found out.The least square support vector machine is used to predict the mean of wind speed.?5?The anti-drift test bed of air curtain is designed and tested.The results show that the wind curtain system can effectively avoid the influence of the non-forward lateral wind on the droplet deposition distribution,and the deposition amount of the wind curtain system is29.53%higher than that of the traditional wind curtain system under the condition of horizontal simulation of natural wind.For the conventional fixed wind curtain with the same diversion structure,the bimodal deposition ratio and the deposition tail length of the wind curtain system designed in this paper are still significantly reduced.For electrostatic spray,the bimodal deposition ratio and the deposition tail length were reduced by 33.18%and 20.45%respectively,making the deposition effect similar to that of conventional spray under the action of wind curtain.So in this paper,the design of air curtain system can effectively overcome the electrostatic spray droplets are easily affected by the flow stress effect in the transport process and the shortcoming of drift over a long distance.The mean wind speed prediction reduced the movement frequency of the wind curtain system.Compared with the wind curtain system without wind speed prediction,the bimodal deposition ratio of the drift deposition distribution decreased by 28.07%and the deposition tail length decreased by28.4cm.The sedimentary bimodal ratio and the sedimentary tail length were measured in the control group without fuzzy control.The results show that the tail length of the air curtain system can be effectively reduced by the fuzzy control mode,which is 34.6%lower than that of the conventional control mode,while the effect on the bimodal deposition ratio is less,which is 8.8%lower.