3WQ-400型双气流辅助静电果园喷雾机设计与试验

为解决农药雾滴难以沉积到果树叶片背面，克服荷电雾滴荷电量在环境空间中快速衰退的难题。该文提出双气流辅助系统与静电喷雾系统相结合的方法，以拖拉机动力输出轴为液压传动系统动力源，研制了牵引式双气流辅助静电果园喷雾机。试验结果表明，19 kW 的拖拉机动力配置可以满足系统动力要求，轴流风机和离心风机的转速分别为1400、1800 r/min 可以满足所选试验对象对气流速度的要求；单个喷头喷出的雾滴在0.2 m 处的荷质比为1.0 mC/kg，且在喷雾距离为1.8 m 处依然带电；风送喷雾系统的垂直雾量分布规律、气流速度分布规律与纺锤型果树生物量分布规律相一致，其最大雾量与气流速度均出现在0.5～1.5 m 范围内；在施药量为3.5 L/min，作业速度为0.84 m/s 条件下，单侧喷雾时果树叶片正反面雾滴覆盖密度分别为115和47个/cm2，可以满足防治害虫的要求；冠层前部静电喷雾雾滴覆盖密度比非静电喷雾提高了20%，而冠层后部雾滴覆盖密度仅提高了7.2%。该研究为风送静电喷雾机设计与使用提供了参考。

Design and experiment of 3WQ-400 double air-assisted electrostatic orchard sprayer

In order to reduce the decay of the droplet carrying capacity and increase the droplet coverage on hidden area of the foliage, a double air-assisted electrostatic spraying system which included anelectrostatic nozzle, a centrifugal blower, an axial fan and a diaphragm pump was proposed in this study. The power of double air-assisted electrostatic orchard sprayer was from power take off (PTO) of tractor to drive hydraulic pump (CBH-G563-AFHL).There were three hydro-motors in hydraulic system to drive centrifugal blower, axial fan and diaphragm pump separately. The indoor and outdoor tests including charge to mass (CTM), air velocity distribution, vertical distribution of spray volume and canopy droplet coverage was conducted. The faraday cylinder was used to collect spray volume, Key sight 34 410 A digital multi-meter was used to test current, and the CTM was calculated. The result showed the CTM at 0.2 m was reached to 1.0 mC/kg with damping along air direction, but the current could also be tested at 1.8 m. The air velocity distribution, vertical distribution of spray volume was based canopy biomass of spindle type fruit, the two maximum heights were between 0.5 and 1.5 m. The field experiment was carried out in Shanxi during October 14 to 16, 2015. The objective of this experiment was to evaluate the effect of electrostatic charge on foliar spray deposition in a high spindle apple orchard using the double air-assisted electrostatic sprayer. The temperature was 25 ℃, relative humidity was 55%. Experiment plot was a modern standard apple orchard which was 350 m long and 200 m wide, the tree was spindle type apple fruit, three years older, 3.2 m in height, 3.5 m row spacing and 1 m spacing in the rows. Trimming was done every year after harvest. There are iron wires at 0.5,1.5 and 2.5 meters high which had different canopy width of 1.0, 0.6, and 0.3 m, and the foliage density was 7.8, 3.6, 1.97 m. The test was strictly followed the quality of air-assisted orchard sprayer (GB/T 24683-2009). The electrostatic system was switched on and off, in order to evaluate its effect on deposition on exposed and hidden face of the foliar. The flow rate at the nozzles was maintained unchanged across the tests, and the main environmental parameters were measured during the tests, they were air temperature, wind speed, and relative humidity. The water sensitive paper as collectors, the profile sampling strategy was adopted. The sprayer’s working velocity was set at 0.84 m/s, spraying pressure was 0.5 MPa, rotation rate of axial fan and centrifugal blower were 1 400 and 1 800 r/min. Each test condition was replicated three times in the same position. Experimental plot consisted of four adjacent rows sprayed under real conditions, i.e. by passing with the sprayer in all the three inter-rows; foliar sampling was carried out in the central inter-row. Blocks were separated by three unsprayed inter-rows in order to avoid possible overlapping due to spray drift. The test was conducted to determine effects of electrostatic spraying on hidden droplet coverage and droplet distribution on canopy. All statistical analysis and graphical representations were performed using Microsoft excel 2010. Results showed the droplet coverage on exposed and hidden foliage were 115 and 47 dot/cm2 at single spraying at the condition of the spray volume 3.5 L/min and driving velocity 0.84 m/s. This illustrated the single spraying was enough for insect prevention, and double spraying was suggest for preventing disease. The droplet coverage was improved 20% at the outside of tree closed to sprayer using electric spraying, while 7.2% was improved at the outside of tree away from sprayer at beyond. The research can provide technology support for air-assisted electric orchard sprayer designing and spraying standard setting.