基于数据库的多特征融合下旋翼无人机雾滴沉积分布模型研究

With the advantages of high efficiency, strong adaptability, low operating cost and less drift, spraying pesticide by using small UAV(unmanned Aerial Vehicle) has gradually become an important development trend of aviation plant protection. In the complex spray flow field of rotor drones, the model of movement of pesticide solution and ground sedimentation are difficult to determine, and droplet deposition location and deposition amount are difficult to control. The project conducts the research of the influence mechanism of multi - characteristic parameters on droplet deposition characteristics and sedimentary distribution model under rotor air disturbance, with integrated application of numerical simulation, wind tunnel laboratory test and field verification methods. Specifically, Fluent software is used to simulate the distribution of the airflow under the rotor of the spraying operation of the plant protection drone, and the dynamic expression of atomizer under the fusion with multi - feature in spray field through coupling calculation is studied. Based on the database technology, the characteristic information of droplet deposition characteristics under the influence of rotor air turbulence is extracted with the usage of controllable wind speed environment in the wind tunnel, and the prediction model of droplet deposition distribution is established. Analysis and study the accuracy of prediction model in field experiment, and propose model correction method, thus gaining control model of droplet deposition area and precipitation amount during the spraying operation of rotor drone, providing theoretical support and application foundation for increasing target deposition amount, and optimizing operation parameters, efficient spraying in drone spraying operations.

小型植保无人机喷施农药具有作业效率高、适应性强、运行成本低及飘移少等优点，逐步成为航空植保的重要发展趋势。针对农药药液在旋翼无人机作为载体的复杂喷雾流场中的运动和地面沉积模式难以确定，药液沉积位置和沉积量难以控制等问题，本研究综合应用数值模拟、风洞室内试验和田间验证等方法，开展旋翼气流扰动下多特征参数对雾滴沉积特性的影响机理和沉积分布模型研究。具体包括：利用Fluent软件模拟植保无人机喷施作业中旋翼下洗气流场分布，通过耦合计算研究喷雾场中多特征融合下雾滴动力学表达方法；利用风洞可控多风速环境，基于数据库技术提取影响旋翼气流扰动下雾滴沉积特性的特征信息，并建立雾滴沉积分布预测模型；最后田间试验中分析和研究预测模型准确性及模型修正策略，从而获得旋翼无人机喷施作业中雾滴沉积区域和沉积量的控制模型，为无人机喷施作业中增加目标沉积量、优化作业参数、高效喷施提供理论支撑和应用基础。

旋翼植保无人机以其施药快、效率高及作业不受地形条件和作物长势限制等优点，是精准农业航空应用体系的重要环节，且旋翼气流影响下药液在靶标上的沉积特性对提高病虫害防治效果、保障国家粮食安全有重要意义。本项目通过动力学分析、计算流体建模、风洞试验和田间试验等技术与手段，分析多特征参数影响下雾滴沉积特性与沉积规律，揭示旋翼风场对雾滴沉积效果的影响机理，构建雾滴沉积预测模型为无人机田间喷施作业中沉积区域及沉积量控制、缓冲区设置及喷施方法优化提供理论指导。. 旋翼风场是影响植保无人机喷施作业雾滴沉积分布特性的重要因素。基于格子玻尔兹曼方法的数值模拟技术建立无人机前飞作业时多特征参数融合下旋翼风场的仿真模型并进行迭代计算，提出接触面积S1和可穿透面积S2为旋翼风场作业效果的评价指标，研究分析不同飞行高度、飞行速度、侧风风速和作业载荷对旋翼风场空间分布及作业效果的影响，建立多特征参数融合的旋翼植保无人机风场预测模型，仿真分析表明多旋翼植保无人机作业较佳飞行高度为2m，飞行速度为4m/s；自然侧风大于3m/s时，旋翼风场倾斜飘移严重，S1 和S2大幅衰减，随喷施作业的开展，旋翼风场向后倾斜程度增大，S1 和S2分别衰减5%和24%，旋翼下方最大风速值减少约37%；设计研制微型无线风速采集系统，基于田间试验对风场预测模型准确性和一致性进行验证。为揭示多旋翼无人机旋翼下方风场对雾滴沉积分布的影响机理，采用激光粒度仪开展喷雾粒径谱测量试验，基于雾滴粒径分散模型，将离散相雾滴引入仿真模型中，通过设计正交试验，研究旋翼风场影响下雾滴的沉积行为。基于风洞试验结果表明：雾滴的沉积曲线以抛物线形式分布在喷头下方，侧风风速、飞行速度、飞行高度、雾滴粒径相对雾滴沉积规律影响显著，作业载荷变化对雾滴沉积影响不显著。采用多元回归分析建立了多特征参数对雾滴沉积量的预测模型，为增加靶标区域沉积量、提高植保无人机施药效果提供理论支撑和应用基础。