摘要
小型多旋翼植保无人机存在农药飘移、雾滴沉积不均等问题,为此本文结合RANS方程、SST k-ω湍流模型和SIMPLE算法,对耦合六旋翼植保无人机下洗气流场和喷雾雾滴的两相流场进行数值模拟计算,探析环境风速对无人机下洗气流和农药雾滴沉积的影响。机身下方空间点风速试验和模拟值相对误差在15%以内,验证了数值模型的准确性。数值模拟结果表明:植保无人机飞行作业时,来流造成无人机下洗风场出现漩涡,来流速度对机身正下方流场的影响大于其对旋翼正下方流场的影响;侧风造成无人机下洗风场出现较大漩涡,下洗风场稳定性降低;两侧旋翼正下方对称布置喷嘴提高了雾滴沉积均匀性,来流造成雾滴卷积,雾滴飘移量随着来流速度提高而增大。综合各因素,无人机喷嘴应在旋翼下方对称布置,在小型六旋翼植保无人机实际作业时,无人机作业方向需要与外界环境风向保持平行,同时在晴朗环境下施药作业,从而降低雾滴飘移,提高农药利用率。
Small multi-rotor plant protection UAVs have problems such as pesticide drift and uneven droplet deposition.The numerical simulation of the two-phase flow field of coupled six-rotor UAV downwash airflow field and spray droplets was carried out by combining RANS equation,SST k-ωturbulence model and SIMPLE algorithm,and the effect of ambient wind speed on UAV downwash airflow and pesticide droplet deposition was explored.The accuracy of the numerical model was verified by the relative error within 15%between the spatial point wind speed test and the simulated value.The numerical simulation results showed that the incoming flow caused a vortex in the UAV downwash air field,and the impact of the incoming flow velocity on the flow field below the fuselage was greater than that on the flow field below the rotor.The stability of the downwash wind field was reduced due to large vortexes caused by the side wind.Symmetrical placement of nozzles under the rotor improved droplet deposition uniformity.The incoming flow caused droplet convolution,and droplet drift was increased as the incoming velocity increased.In combination with various factors,the UAV nozzles should be symmetrically arranged under the rotor blades.In the actual operation of six-rotor plant protection UAV,the UAV operation direction needed to be parallel to the outside wind direction in a clear environment,so as to reduce droplet drift and improve pesticide utilization.
作者
张健
张超
陈青
周宏平
杨风波
茹煜
ZHANG Jian;ZHANG Chao;CHEN Qing;ZHOU Hongping;YANG Fengbo;RU Yu(Co-Innovation Center of Efficient Processing and Utilization of Forest Resources,Nanjing Forestry University,Nanjing 210037,China;College of Mechanical and Electronic Engineering,Nanjing Forestry University,Nanjing 210037,China)
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2022年第8期74-81,共8页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(51906111)
江苏省农业科技自主创新资金项目(CX(19)3077)
关键词
小型六旋翼植保无人机
环境风速
数值模拟
下洗气流
喷雾场
耦合风场
small six-rotor plant protection UAV
ambient wind speed
numerical simulation
downwash airflow
spray field
coupled wind field
作者简介
张健(1998—),男,博士生,主要从事精确农药喷雾研究,E-mail:zj2021@njfu.edu.cn;通信作者:陈青(1986—),男,副教授,主要从事智能农林装备研究,E-mail:qchen@njfu.edu.cn
