Relationship Between Spraying Droplet Size By Two Kinds Of Rotor UAV With Droplet Deposition Result

In recent years,it has gradually emerged that using UAV for plant protection spraying in China.Spraying pesticides by UAV,which has higher working efficiency and wide adaptability,could be effectively combined with low volume and ultra-low volume spraying technology to ensure the effect of spraying and reduce the dosage of pesticide,to achieve the purpose of using less pesiticides.The effect of droplets deposition spraying by UAV is mainly effected by flight parameters and spray droplet size,but the research on effect of droplets deposition mainly concentrated on t he flight parameter setting,the research about droplet size is less.This paper mainly focuses on spray droplet size,researched the atomization parameters of UAV,and analyzed the relationhip between droplet size and deposition effect in laboratory and field when spray by UAV.The results and conclusions are as follows:(1)Analysis of atomization parameters of UAV.We used laser particle sizeanalyzer tomeasure droplets'diameter spraying by 5 hollow cone type pressure nozzles whose nozzle orifice diameter were different,with 8 kinds of spray pressure.And the overall VMD is between 118~229?m.Then analyzed the significance of the effect of nozzle orifice diameter and spray pressure on droplet volume median diameter by SPSS software,and the significance level were all 0.000 which was less than 0.01.It indicate thatnozzle orifice size and spray pressure have a significant effect on the droplet size of the hollow cone type pressure nozzles,and spray droplet size decreases with increasing of spray pressure and fluctuate along with the increase of nozzle orifice size.(2)Relationhip between droplet size and deposition effect in laboratory when spray by UAV.Based on the spray droplet parameters of the 5 nozzles,the nozzle whose orifice diameter is 1.0 mm was selected for indoor droplet deposition test.We measured its droplets(droplets'VMD is 137.64?m,152.46?m,172.26?m and 198.05?m)deposition density,coverage and liquid deposition volume per unit area at 0.5m,1.0m and 1.5m respectively from the nozzle under four kinds of spray pressure.And analyzed the variation coefficient of droplet depositino at different heights in indoor enviroment.The results was that droplets whose VMD is 137.64?m in 1m has the highest deposition volume per unit area—1.418?L/cm~2,droplets whose VMD is 172.26?m in 1m has the lowest deposition volume per unit area—0.447?L/cm~2.It means that the deposition of small particle size droplets is larger than that of large particle size droplets,but the distribution uniformity of large particle size droplets is better than that of small particle size droplets in the ideal environment of laboratory.(3)Relationhip between droplet size and deposition effect in field when spray by UAV.We used colorimetric method for outdoor experiment.And the deposition amo unt of two rotor-type unmanned aerial vehicles(UAVs)in the upper,middle and lower canopy of rice was detected by using Xylidine Ponceau 2R as tracer.Then we analyzed the significance of droplet deposition,and the results was that the Sig.value of factor of vertical sampling position was 0.032 and the Sig.value of factor of experimental co mmunity was 0.000.The coefficient of variation of the droplet deposition at each height of of every test plot was calculated,the results was follows:variation coefficient of deposition of plot A was 33.86%?32.04%?34.06%in the upper,middle and lower,the plot B was 25.59%?17.05%?14.67%,plot C was 20.36%?24.60%?21.22%,and plot D was 8.40%?17.86%?14.92%.It showed:In the field experiment,the deposition between the upper,middle and lower layers of the rice canopy was significantly different when the UAVs were used for spraying,the distribution uniformity and penetration of the droplets in the canopy were great.And the distribution of droplets is different from that of indoor experiments,the smaller the droplet size in the field experiment,the more the deposition per unit area,and the better the droplet distribution uniformity.Under the action of wind field produced by UAV's rotors,because the droplets can effectively penetrate the canopy and reach the depths of the canopy with the action of the wind field formed by UAV's rotors,and the distribution uniformity of the lowest layer of the canopy is not worse than that of the upper layer.