大载荷植保无人直升机喷雾气液两相流动数值模拟  

Numerical Simulation on Gas-liquid Phase Flow of Large-scale Plant Protection Unmanned Aerial Vehicle Spraying

作　　者：王军锋[1] 徐文彬 闻建龙[1] 王晓英[1] 罗博韬 

机构地区：[1]江苏大学能源与动力工程学院,镇江212013

出　　处：《农业机械学报》2017年第9期62-69,共8页Transactions of the Chinese Society for Agricultural Machinery

基　　金：江苏省农业科技自主创新资金项目(CX(15)1038)

摘　　要：为研究大载荷植保无人直升机喷雾流场特性,基于FR-200型大载荷植保无人直升机喷洒系统,建立FR-200型大载荷植保无人直升机无植物冠层三维雾滴沉降仿真模拟平台,利用Fluent软件的SST k-ω湍流模型和DPM离散相模型对无人直升机喷雾沉降过程进行了仿真模拟,分别研究了飞行速度、喷杆相对位置、喷施角度对喷雾流场的影响,并进行户外试验验证。试验结果表明,下洗流场垂直方向速度(Z向)呈不对称分布,旋翼x/R为0.8处垂直方向速度(Z向)最大;仿真模拟的雾滴沉积总量与户外试验的雾滴沉积密度基本一致,线性决定系数R2为0.999 6,无人直升机前飞速度与雾滴群抗飘移系数及沉积量呈线性关系,前飞速度3 m/s时,靶标上雾滴总沉积密度为4.208μL/cm^2,前飞速度5 m/s时,靶标上雾滴总沉积密度为1.766μL/cm^2;随着采样面的升高,雾滴群抗飘移性能增强;位于喷杆不同位置处喷头的抗飘移性能不同,主要表现在位于喷杆两端的喷头1和9受到旋翼尾涡的影响,雾滴群抗飘移性能变差,机身正下方的喷头5由于机身阻挡作用,造成雾滴群分散性增加,雾滴因垂直方向动能衰减而难以到达采样面;喷施角度越小,雾滴群总体抗飘移性能越好。In order to study the spray flow filed characteristic of large-scale plant protection unmanned aerial vehicle （UAV） , based on the spray system of FR - 200 large-scale plant protection UAV, the simulation platform of depositing spray droplets without plant canopy was established. The SST κ - ω turbulence model and the DPM discrete phase model were adopted to simulate the deposition process of UAV spray droplets. By means of numerical Fluent simulation software, the flight speed, spray boom relative position and spraying angle impact on the spray flow field were studied, field test was done to verify the results of simulation. The vertical velocity distribution of FR - 200 UAV downwash flow field was unsymmetrical. The UAV speed had linear relationships with both the droplet swarm anti-drift coefficient and deposition, the total amount of the target droplets deposition density were 4. 208 μL/cm2 when flying speed was 3 m/s, the total amount of the target droplets deposition density were 1. 766 μL/cm2 when flying speed was 5 m/s. The anti-drift coefficient was 87.5% , 93.0% and 96.4% at sampling plane height of 0 m, 0.5 m and 1.0 m when flying speed was 4 m/s, respectively. With the increase of sample surface height, the anti-drift performance of droplets was promoted. The drift phenomenon of nozzles was serious which was installed on both sides of the spray boom. The nozzles were affected by the trailing vortex which caused the droplets drift. The rotor downwash flow increased spray droplets initial kinetic energy, the spray droplets acceleration was caused by gravity and downwash flow. The dispersion of number 5 nozzle spray droplets was increased due to the blocking effect, and it was hard to reach the sample surface due to the vertical kinetic energy attenuation of droplets. The smaller the spraying angle was, the stronger the droplets total anti-drift performance became.

关 键 词：无人直升机 大载荷 植保 数值模拟 

分 类 号：S252[农业科学—农业机械化工程]