航空施药旋转液力雾化喷头性能试验

    Performance experiment of rotary hydraulic atomizing nozzle for aerial spraying application

    • 摘要: 无人机航空喷雾将会在未来几年的植物病虫害防治作业中发挥重要作用。为实现无人机低空、低量、高功效的喷洒需求,该文针对兼备液力雾化和离心雾化优点的旋转液力雾化喷头进行了性能试验研究,利用喷头雾化性能测试系统对喷孔直径、喷雾压力、电机转速因素对喷头雾滴粒径、沉积分布、喷幅和功率消耗的影响进行了试验研究。结果显示,喷头旋转电机电压相比喷孔直径、喷雾压力参数对雾滴粒径影响更显著,随着电机电压增加,雾滴粒径变小,雾化效果好;电机电压对幅宽也有明显影响,随着电极电压增加,喷雾角度变大,幅宽明显增加,雾滴沉积量在喷幅范围内呈现正态分布。通过试验结果优选出适合无人机的旋转液力雾化喷头的最佳工作参数:电机电压为10 V,喷雾压力为0.35 MPa,喷嘴孔径是0.7 mm,该工作参数下,液泵功率消耗率最低,雾滴平均粒径为112.35 μm,喷幅为3.88 m,电机功率消耗为8.6 W。该文的研究结果为开发适用于无人机的新型喷洒雾化装置,提高无人机作业质量和喷洒功效提供理论依据和技术支持。

       

      Abstract: Abstract: Pests and plant diseases cause damage at different levels to China's grain production and economic crops every year. The annual area damaged by pests and diseases is about 470 000 000 hm2, resulting in significant yield losses-about 20% of the total grain yield. A small-size unmanned helicopter has the advantages of flexible operation, strong automatic control ability, and less droplet drift. In addition, pesticides it sprays can penetrate a crop canopy assisted by rotor airflow. Hence, the agricultural chemical control for pests and diseases in medium and small sized fields using a small-size unmanned helicopter is an important means to guarantee grain production. It is one of effective methods for Chinese pesticide-spraying mechanization.In order to realize the low-altitude, low-volume, and high-efficiency spraying demand of an unmanned aerial vehicle (UAV), its spray system, which is the key UAV part, must meet the requirements of lightweight, low-volume spraying and uniform spray. Based on the domestic and foreign UAV nebulization technology of agricultural chemical spray nozzles, we tested the performance of rotary hydraulic atomizers, which combined the advantages of both centrifuge atomization and liquid atomization, in this study. A comprehensive performance test system of nozzle atomization was applied to detect the effect of important factors including structure parameters (nozzle diameter), spray parameters (spray flow rate and pressure), and operating parameters (rotational speed) on nozzle atomization efficiency (droplet size), deposition distribution, and spray span. We analyzed the correlation between spray parameters and pump power consumption. Combined with the effect of motor voltage on motor power, the optimum nozzle working parameters were selected. The results showed that the voltage of a nozzle rotary motor had a more significant effect on droplet diameter than nozzle diameter and spray pressure parameters did. Along with the increase of motor voltage, droplets became smaller, giving a better atomization effect. Motor voltage also notably influenced spray span. The more the voltage was, the bigger the spray angle was, and the larger the span became. Droplet deposition presented normal distribution in the spray range. The best working parameters (10 V of motor voltage; 0.35 MPa of spray pressure; 0.7 mm of nozzle diameter) for UAV rotary hydraulic atomizers were determined by the comprehensive test results. When these parameters were applied, the pump power consumption rate was lowest, the average droplet size was 112.35 μm, the spray span was 3.88 m, and the motor power consumption was 8.6 W. The nozzle atomization performance test system adopted in the present study has been calibrated and analyzed for error in other literature. Its experimental system error displayed was less than 1%, so the test results obtained through this platform are reliable.The results shown here provide a theoretical basis and technical support for the mounting of this novel UAV spray device-the rotary hydraulic atomizing nozzle-onto an UAV to perform relative experiments to improve UAV operating quality and spraying efficiency in the future.

       

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