无人植保机施药雾滴空间质量平衡测试方法

为了研究精准作业参数(速度、高度)下的无人植保机施药雾滴空间分布和下旋气流场特性,该文提出了一种无人机施药雾滴空间质量平衡测试试验方法,并且使用该方法对3种无人机进行了田间实际试验研究,结果表明:该方法可以有效获得准确飞行速度和高度下无人机施药雾滴空间分布情况和下旋气流场分布情况,在平均风速1.7 m/s、平均气温31.5℃、平均相对湿度34.1%的条件下,飞行高度2.5 m、速度5.0 m/s时,3WQF80-10型无人机喷雾作业雾滴在上风向部、顶部、下风向部和底部的平均分布比例为4.4%,2.3%,50.4%和43.7%;CG-Q60S型无人机雾滴在4个方向上平均分布比例为2.5%,1.5%,43.2%和52.8%;LXD8-3WD10型无人机雾滴在4个方向上平均分布比例为1.9%,2.0%,21.9%和74.7%。雾滴空间质量平衡分布规律符合下旋气流场分布规律,无人机下旋气流风场的测量是分析雾滴在空间不同部位分布的重要手段。研究结果可为低空低量无人植保机施药技术研究和建立无人植保机低空低量施药田间雾滴沉积与飘失测试标准提供参考。

Testing method of spatial pesticide spraying deposition quality balance for unmanned aerial vehicle

The unmanned aircraft application techniques and equipment are rapidly developing in China, and there are more than 200 manufacturers of unmanned aerial vehicle (UAV). A range of different types of remote controlled UAVs, whose working efficiency can be up to 6 hm2/h with 5-30 L liquid tank and 2-10 m spraying swath under different application conditions, have been applied for crop field chemical control. From the year of 2011, Chinese researchers started to study the UAV pesticide application techniques and the research focus was to explore the effect of working parameters (flight height and flight velocity) on spray deposition, drift and biological efficacy. However, most of those studies emphasized the spray deposition on the ground and in the canopy, and there was no study involving spatial deposition distribution. The choice of droplet sampling material and the accurate measurement of working parameters were always 2 hard problems in UAV pesticide application test. In order to explore the spatial spray deposition distribution, the downwash flow field characteristics for UAV pesticide application with accurate flight height and velocity and the relationship of these 2 aspects, a novel measurement method was proposed in this paper, and 3 typical models of UAVs were tested using this method in wheat field in Anyang, Henan Province from May to June, 2015. A cuboid aluminum spatial spray deposition sampling frame (SSDSF) with monofilament wires was made for collecting the droplets of UAV pesticide application in 4 directions, and a set of multi-channel micro-meteorology measurement system (MMMS) was applied for measuring the downwash wind speed in 3 directions. The SSDSF was placed outside the edge of the wheat field. The MMMS had 16 wireless micro-meteorology sensors, and all these sensors, divided into 2 lines, were arranged below the UAV flight path in the wheat field. Beidou navigation satellite system and airborne global position system were jointly used for controlling and recording the working height and velocity of UAVs. The flight height was set as 2.5 m and the velocity was set as 5.0 m/s. Two sets of weather stations were respectively fixed at 2 and 6 m to measure the environmental parameters at test site. In every test, the operator controlled the UAV to take off at the distance of 20 m from the edge of the field. When the UAV reached the required height, open the spray system and let the UAV fly over the experimental field and go through the SSDSF. After tests, the monofilament wires on the SSDSF were collected for measuring the absorbance of the tracer brillantsulfoflavin by the fluorescence spectrometer, and the spray deposition, deposition rate and distribution ratio could be figured out. The results showed the distribution of the spatial spray deposition and the downwash flow field of UAV could be measured effectively at exact flight height and velocity via this method. When the average wind speed was 1.7 m/s, the average temperature was 31.5℃ and the average relative humidity was 34.1%, the average distribution ratios of spray deposition for the 3WQF80-10 type UAV on the upwind part, the top part, the downwind part and the bottom part were 4.4%, 2.3%, 50.4% and 43.7%, respectively; that for the CG-Q60S type UAV on these 4 parts were 2.5%, 1.5%, 43.2% and 52.8%, respectively; that for the LXD8-3WD10 type UAV on these 4 parts were 1.9%, 2.0%, 21.9% and 74.7%, respectively. By comparing the measurement results of the spatial spray deposition distribution and the downwash flow field, it is found that the regularities of spatial deposition distribution completely conform to the regularities of downwash flow field distribution, and the downwash flow field characteristic measurement is a valid method for the analysis of spatial spray deposition distribution. The results can provide valuable information for the research of UAV pesticide application techniques and the establishment of the standard of spray deposition and drift tests of UAV in crop field.