侧向风对航空植保无人机平面扇形喷头雾滴飘移的影响

陈盛德; 展义龙; 兰玉彬; 燕颖斌; 钱士程; 陈威任; 陈乐君

doi:10.7671/j.issn.1001-411X.202105025

侧向风对航空植保无人机平面扇形喷头雾滴飘移的影响

Influence of crosswind on droplet drift of flat-fan nozzle in aviation plant protection UAV

摘要

摘要:
目的侧向风是影响植保无人机航空喷施雾滴飘移和作业效果的主要因素。探究航空植保喷施过程中侧向风对雾滴沉积和飘移的影响，为植保无人机航空喷施作业参数的选择和作业关键部件的改进提供数据支持和理论指导。

方法以常用平面扇形喷头Lechler系列的LU 120-015和LU 120-03标准压力喷头为研究对象，基于计算流体力学离散相模型的粒子跟踪技术，在适宜的边界条件下对喷施作业过程中风洞内雾滴流场和农药喷洒离散相进行模拟试验；通过仿真模拟对平面扇形喷头喷施的雾滴沉积和飘移分布情况进行可视化分析，探究雾滴粒子在不同侧风风速条件下的飘移特性；在农业航空专用风洞中，采用近似条件对雾滴的沉积飘移特性进行试验验证和分析。

结果仿真模拟结果表明，随着侧向风速的增加，离散相雾滴粒子飘移程度越严重，雾滴水平飘移越明显。随着侧向风速的增加，模拟离散相雾滴粒子的准确沉积率(R_a)呈指数下降，由14.11%下降到0.66%；水平飘移率(R_h)呈线性增加，由14.25%增加到60.58%。风洞试验结果表明，在侧风风速分别为1、3和6 m/s的条件下，雾滴的R_h分别为0.4%、48.1%和75.1%，且雾滴在风洞内部会随着侧风风速的增加发生一定程度的卷扬现象。仿真模拟与风洞测试试验的R_h具有显著相关性(R²=0.963，P<0.05)。

结论仿真模拟对航空喷施条件下的雾滴飘移具有较好的预测效果；采用仿真模拟辅助风洞试验测试的方法，可以比较准确地得出航空植保无人机作业中常用平面扇形喷头的雾滴沉积与飘移情况。

Abstract:
Objective Crosswind is the main factor affecting droplet drift and spraying effect of aerial spraying for plant protection unmanned aerial vehicle (UAV). To explore the influence of crosswind on droplet deposition and drift during aerial spraying, and provide data support and theoretical guidance for selection of operation parameters and improvement of key components of aerial spraying for plant protection UAV.

Method Lechler series LU 120-015 and LU 120-03 standard fan-shaped pressure nozzles were taken as the research objects. Based on the particle tracking technology of computational fluid dynamics (CFD) discrete phase model, the simulation tests of droplet flow field and pesticide spraying discrete phase in the wind tunnel were carried out under suitable boundary conditions. Through the simulation, the deposition and drift distribution of droplets sprayed by fan nozzle were analyzed visually to explore the drift characteristics of droplets at different lateral wind speeds. The deposition and drift characteristics of droplets were tested and analyzed in the agricultural aviation special wind tunnel under the similar conditions.

Result The simulation results showed that the drift degree of discrete phase droplets was more serious and the horizontal drift of droplets was more obvious with the increase of lateral wind speed. With the increase of lateral wind speed, the accurate deposition rate (R_a) decreased exponentially from 14.11% to 0.66%, and the horizontal drift rate (R_h) increased linearly from 14.25% to 60.58%. The wind tunnel test results showed that the R_h values of droplets were 0.4%, 48.1% and 75.1% at the lateral wind speeds of 1, 3 and 6 m/s respectively, and the droplets appeared the winding phenomenon to a certain extent in the wind tunnel. The results of correlation analysis showed that there was a significant correlation between the horizontal drift rates of computer simulation and wind tunnel test, and the R² was 0.963 (P<0.05).

Conclusion The simulation test has a good prediction effect on droplet drift under aerial spraying condition. The simulation-assistanted wind tunnel test method can get a reasonable result of the droplet deposition and drift of the flat-fan nozzle commonly used in aviation plant protection operation.

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