面向树干对靶施药的近地表药液飞行规律及超前飘移控制研究

Defoliators with the habit of bidirectionally migrating from ground to crown via tree trunk can be obstructed by targeted applying barrier treatment on tree trunks. But droplet drifting occurred during targeted spray caused by environmental meteorological conditions and spray technical parameters, which results in low control efficiency. Therefore, in this research classic tree trunks in China will be treated as spray targets. The factors influencing the droplet flight behavior and how they influence it in mobile targeted spray will be figured out and the corresponding advanced drift control method will be developed. Starting with the gas-liquid two-phase flow theory of the nozzle’s spray sheet, a nozzle atomization mathematical model which can demonstrate the spatial distribution of droplet diameter and velocity will be established by extending the model with the data detected by sensors. Setting the nozzle atomization mathematical model as the spray source, Computational Fluid Dynamics (CFD) modeling will be conducted to analyze the influence mechanism of various wind characteristics and spray technical parameters to the spray droplet flight behavior. A prediction model of spray droplet flight for static nozzle is expected to be established to estimate flight time, correct deposition and drifting based on Relevance Vector Machine. On this basis，a total regression prediction model with the output as the droplet deposition accuracy will be developed by introducing into nozzle speed and spray yaw angle. Finally, an advanced drift control strategy for mobile barrier spray will be proposed aiming to optimize the droplet deposition accuracy on the tree trunk. The research results have an important scientific significance for forest tree trunk targeted barrier spray and provide technical support for optimizing the sprayers.

对树干精准喷施障碍药带可有效阻隔具有迁移习性的食叶害虫，但移动喷施过程中受环境和喷施参数多因素作用导致药液飘散，影响防治效果。因此，本申请拟以我国典型林木为施药对象，探究障碍药带移动喷施过程中药液飞行行为的影响因素及规律，建立其超前飘移控制方法。尝试从喷头喷流幕气液二相流理论模型入手，结合传感观测数据扩展理论模型后建立能够表征雾滴粒径和速度空间分布的喷头雾化模型；以此作为喷雾源，进行计算流体动力学（CFD）三维仿真，分析不同近地表风特性和喷施参数对药液雾滴群飞行行为的影响，采用RVM方法建立静态喷头下可推算飞行时间、准确沉积及飘移量的药液飞行模型；在此基础上，引入喷头移动速度和施药摆角，以准确沉积率作输出，进一步建立涵盖施药时机和施药摆角的全回归预测模型；以准确沉积率最优为目的，最终建立移动喷施障碍药带超前飘移控制策略，为障碍药带精准喷施奠定理论基础，并为相关植保机械参数优化提供技术支撑。

对树干精准喷施障碍药带可有效阻隔具有迁移习性的食叶害虫，但移动喷施过程中受环境和喷施参数多因素作用导致药液飘散，影响防治效果。因此，本项目以我国典型林木为施药对象，探究障碍药带移动喷施过程中药液飞行行为的影响因素及规律，建立其超前飘移控制方法；通过从喷头喷流幕气液二相流理论模型入手，结合传感观测数据扩展理论模型后建立了能够表征雾滴粒径和速度空间分布的喷头雾化模型；以此作为喷雾源，进行计算流体动力学（CFD）三维仿真，分析了喷施参数对药液雾滴群飞行行为的影响；采用点云稀疏、放样的算法建立了树干三维实体模型，并进行了雾滴撞击树干三维仿真分析；引入喷头移动速度、风场和施药摆角，以准确沉积率作输出，进一步建立涵盖施药时机和施药摆角的全回归预测模型；以准确沉积率最优为目的，最终建立移动喷施障碍药带超前飘移控制策略，为障碍药带精准喷施奠定理论基础，并应用在相关植保机械中。