高郁闭度冠层气流辅助喷雾药液沉积衰减机理与抑制策略

In the crop growth later period, crops are easy to form a high density canopy. The coverage obscured by stems and foliage incurs a "droplets deposition decay" phenomenon in spraying, which has seriously affected chemical control and become the bottleneck to improve the effective utilization of pesticides. The existing spray machinery design theory could not properly solve the problem of droplet deposition decay in the internal high density canopy. This project regards the air-assisted spray process within high density canopy as research object, from the perspective of porous media formed by group of stalk, stems and foliage, using numerical simulation, high-speed image analysis and fluorescent tracer techniques to explore morphological variation of individual stem and leaf and evolution characteristic of porous media of crop group driven by airflow, to research the droplets transportation, penetration and deposition process in high density canopy driven by airflow, and to clarify the mechanism and factors of droplet deposition attenuation; According to the characteristics of local density distribution and porosity evolution of crop canopy driven by airflow, the multipath strategy is to innovated to suppress droplets deposition attenuation phenomenon. And then to form "air-assisted spray pattern design" theory integrated by airflow patterns, spray patterns and parameters control, which could to achieve high droplets transportion capacity and uniform deposition in dense canopy, and to improve effective utilization of pesticides; To create droplets space deposition performance test system and deposition decay suppression test bench for air-assisted spray, to verify the effectiveness of suppression strategies and theoretical models. The Research results will yield theoretical fundamnetals and technical supports for machinery design and application techniques of reliable pesticides control.

作物生长中后期易形成高郁闭度冠层，枝叶遮蔽使施药出现"雾滴沉积衰减"现象，严重影响病虫害防治效果，成为提高农药有效利用率的瓶颈。现有药械喷雾设计理论无法解决高郁闭度作物内部的"雾滴沉积衰减"难题。项目以高郁闭度作物的气流辅助喷雾过程为研究对象，从秆茎叶群体形成多孔介质的视角切入，运用数值模拟、高速影像分析与荧光示踪等技术，探索气流驱动的茎叶个体形态变化及群体多孔介质特性演化规律，研究气流作用下雾滴在高郁闭度冠层中的运输、穿透和沉积过程，阐明雾滴沉积衰减机理；依据冠层局部密度分布和气流驱动的孔隙率演化等特点，创新雾滴沉积衰减多路径抑制策略，形成气流模式、喷雾模式和参数控制集成的"气辅喷雾模式设计"理论，实现高郁闭度冠层内雾滴的高输送能力和均匀沉积，提高农药有效利用率；创制气辅喷雾空间雾滴沉积测试系统与衰减抑制台架，验证理论模型与抑制策略的有效性。为高防效药械设计和应用提供理论基础和技术支撑。

作物生长中后期易形成高郁闭度冠层，枝叶遮蔽使施药出现"雾滴沉积衰减"现象，成为病虫害防治瓶颈，需要发展新的喷雾设计及决策理论加以解决。. 项目首次提出以分层孔隙率视角作为高郁闭度冠层多孔介质特性的表征参数，发明并搭建了分层孔隙率可调的空间雾滴沉积标准化测试装置，建立了相应的空间雾滴沉积CFD模型，搭建了1：1仿真植株试验模型，验证了高郁闭度冠层等效为多孔介质的合理性，分析了冠层分层孔隙率参数对雾滴空间运移、沉积行为的影响规律。. 探索了辅助气流作用下枝叶弯扭变形及植株群体孔隙率变化规律。根据典型作物棉花的秆茎叶力学特性测试，建立辅助气流下枝叶变形数学模型，利用CFD耦合模型及风载试验，修正模型准确性，分析了辅助气流对植株群体分层孔隙率分布的影响规律。. 基于作物形态特征，构建了以生长度日（GDD）为主驱动变量的冠层分层孔隙率估算模型；借助冠层机器视觉信息，建立了基于卷积神经网络的作物生长信息检测与生长期智能分类模型，为估算模型提供修正依据，实现了田间植保精度匹配的冠层分层孔隙率快速获取。. 创制了气流辅助喷雾空间雾滴沉积测试系统，建立了高郁闭度冠层下喷雾决策模型，依据作物冠层分层孔隙率的分布及气流辅助作用下的演变规律，开展多路径沉积衰减抑制试验，形成了面向高郁闭度作物的以分层孔隙率为核心参数的“气辅喷雾模式设计”理论。. 理论研究成果应用：针对日光温室高郁闭度作物特征，优化设计喷雾施药模式，完善了面向高郁闭度作物的以孔隙率为核心参数的“气辅喷雾模式设计”理论。创制了适用不同大田作物的两位一体、三位一体、温室弥雾机三种植保作业机械。将农药利用率提高10-15%，减少农药用量10%以上。. 项目发表论文13篇，其中SCI/EI收录7篇，获得农业机械学报年度最佳论文一篇。另有两篇论文已投农业工程领域Top SCI源刊。申请国家专利29项，其中发明18项，授权4项，实用新型11项，授权9项，形成了以高郁闭度作物气辅喷雾理论的知识产权专利簇。参加国内外学术会议10人次，培养硕、博士研究生10名，获奖4项。. 综上，项目在精准施药领域开创了特色理论研究与应用。