鹅颈式远射程苗圃风送喷雾机设计与试验

Design and test of goose-neck long-range air-assisted sprayer for nursery

苗圃种植呈现“密植、连片”的特点,传统风送式喷雾机难以兼顾“气流射程远、雾滴沉积均匀”的双重要求,导致药液附着率低、雾滴飘移等问题。针对上述问题,该研究基于CFD仿真与自由淹没射流理论设计“鹅颈式三出风口”分流结构并通过计算获得其关键参数,研制出鹅颈式远射程苗圃风送喷雾机,并开展了气雾流场分布规律测试与田间试验。试验结果表明,风机转速大于等于2 200 r/min时,3个出风口的气流速度满足射程20.0 m的喷施要求,轴向上气流能量衰减速度缓慢且均匀;风机转速为2 400 r/min,喷雾机行驶速度为1.0 m/s时,雾滴沉积量随喷施距离增大呈现少-多-少的趋势,雾滴沉积量较为均匀,变异系数为28.87%;田间试验冠层上部叶片正反面雾滴覆盖率分别为51.93%、24.38%,下部分别为42.99%、19.26%;冠层上部叶片正反面平均雾滴沉积量分别为13.34和2.82μL/cm^(2),下部分别为5.44和2.63μL/cm^(2),满足植保喷雾作业需求。研究结果可为苗圃风送式远射程施药装备研发提供新思路。

Plant nursery presents the characteristics of close planting.It is difficult for the traditional air-assisted sprayer to take into account the dual requirements of"long spray range and uniform droplet deposition",which leads to the problems of low deposition and drift.A goose-neck long-range air-assisted sprayer for nursery was designed based on CFD simulation and free submerged jet theory.The three-outlet flow guide device,as the core component of the sprayer,has outlets A,B,and C.Air outlet A adopts a circular arc shape,while air outlet B and air outlet C are gradually expanding circular arc tubes.The three air outlets are interconnected and correspond to different areas,which can meet the requirements of far-range spray operation.The optimized curvature radius parameters are conducive to maintaining a uniform and stable flow state of airflow.Based on the free submergence jet theory,the air outlet and fan parameters were determined,and airflow field distribution measurement experiments were conducted.when the fan speed is no less that 2200 r/min,the airflow speed can fit the spraying requirement as far as 20 m.The average airflow speed was 2.33 m/s at a height of 0.8 m;the airflow speed was 1.74 m/s at 20.0 m.The variation coefficient of airflow speed at different heights was less than 30%,indicating that the energy attenuation rate was slow and uniform,and the airflow could carry droplets to spray far away at a uniform speed.The droplet deposition test shows that the variation coefficient of the droplet deposition amount of the goose-neck long-range nursery air spray is 28.87%.To ensure the reliability of our findings,a comprehensive field test of the sprayer were conducted.Citrus seedlings,with an average height of 80 cm,were chosen as the test subjects,and the test was carried out in the nursery of the Citrus Research Institute of Chongqing Southwest University.Following the guidelines of GB/T17997-2008,the droplet deposition effect and drift rate at various distances were tested.The experimental results show that the fan speed of the sprayer is 2400 r/min and the driving speed is 1 m/s;the droplet deposition tends to be less-more-less with the increase of distance.The droplet coverage rates of the upper and lower leaves of the canopy were 51.93%and 24.38%,respectively,and 42.99%and 19.26%,respectively.The average droplet deposition on the front and back leaves of the upper canopy was 13.34 and 2.82μL/cm^(2),respectively,and that on the lower canopy was 5.44 and 2.63μL/cm^(2),respectively,which met the requirements of plant protection spraying operation.It can be seen that the sprayer shows good spray range performance and droplet deposition uniformity,which can meet the agronomic requirements of the complex planting environment in the nursery and the industrial standards of the airassisted sprayer.At present,in Chinese nurseries such as citrus,pear,and apple,etc,manual machinery accounts for a large proportion of spraying equipment,and the demand for specialized sprayers is becoming increasingly urgent.Due to the close planting mode of the nursery,it can be considered that the two modes of spray with high clearance spraying and long-range airflow-assisted spraying have application prospects.Compared with high-clearance spraying,long-range airflow-assisted spraying has the characteristics of high operating efficiency and good horticultural trafficability and is more suitable for small and medium-sized nurseries.However,improving the delivery distance of aerosol flow while ensuring good uniformity of droplet deposition is still a challenge.The results of this study can provide a new idea for developing a long-range air-assisted sprayer for nurseries.