六旋翼植保无人机风场竖直分布特性数值模拟与验证

Vertical Distribution Law of Six-rotor Plant Protection UAV Based on Multi-feature Parameters

植保无人机作业过程中,旋翼风场竖直方向分布特性对雾滴的输运效应及作物冠层的扰动作用直接影响施药沉积效果。本文以六旋翼植保无人机风场竖直分布为研究对象,采用基于格子玻尔兹曼方法的数值模拟技术建立了无人机前飞作业时旋翼风场仿真模型,并根据正交试验方法研究了多特征参数融合对风场竖直分布特性的影响。仿真结果表明,竖直分布风场垂直于飞行方向对称分布,当飞行高度和飞行速度增加或作业载荷减小时,风场强度逐渐减弱;竖直分布风场沿侧风方向倾斜,侧风风速大于3 m/s时,风场横向倾斜超45°。基于此,采用恒温差热敏芯片研制了微型无线风速采集系统,并开展了植保无人机风场竖直分布特性的多因素田间验证试验,试验结果表明:仿真模拟与田间试验旋翼风场竖直分布规律基本一致,相对误差较小,风场竖直分布特性具有较好的一致性;数值模拟方法可有效模拟植保无人机飞行过程的非定常流动,仿真与田间试验结果为植保无人机雾滴沉积的研究提供了理论基础。

During the operation of plant protection UAV,the vertical distribution law of the rotor wind field and the wind speed have a direct impact on the transport effect of droplets and the disturbing effect of the crop canopy.Taking the vertical distribution of the six-rotor UAV as an object,the simulation model of the rotor wind field using the numerical simulation technology based on the lattice Boltzmann method was established when UAV flying.In addition,according to the orthogonal test method,the influence of multi-feature parameter fusion on the vertical distribution of wind field and wind speed was studied.The simulation results showed that the vertical distribution wind field was symmetrically distributed perpendicular to the flight direction.When the flight height and flight speed increased or the operating load decreased,the wind field intensity was gradually weakened;the vertical distribution wind field was inclined along the crosswind direction,and when the crosswind wind speed was greater than 3 m/s,the lateral inclination of the wind field exceeded 45°.Besides,a miniature wireless wind speed acquisition system was developed based on the constant temperature difference thermal chip,and a multi-factor field verification test of the vertical distribution characteristics of the wind field of the plant protection UAV was carried out.The results showed that the vertical distribution law of the rotor wind field between the simulation and the field test was basically the same,the relative error was small,and the vertical distribution of wind field had good consistency.The numerical simulation method can effectively simulate the unsteady flow during the flight process of plant protection UAV,and the simulation and field test results would provide a theoretical basis for the study of the droplet deposition of the plant protection UAV.