中文摘要：

针对农用植保无人机超低容量喷施作业时,使用液力喷嘴产生的雾滴粒径较大,离心喷嘴结构复杂、价格较高等不足,基于旋流雾化的原理并采用模块化方法,提出了一种超低容量旋流喷嘴结构。通过对旋流喷嘴内流场的流体动力学行为和雾化特性进行数值分析与试验,明确了流体的物理特性和旋流喷嘴的结构参数等对雾化性能的影响规律。研究结果表明,液膜表面的正弦波失稳是导致锥形液膜碎化为雾滴的主要原因,在旋流喷嘴的结构参数中,喷嘴出口直径是喷嘴雾化性能的主要影响因素。当喷嘴出口直径从1增大至1.5 mm,喷雾流量平均增大了46.23%,喷雾角平均增大了29.77%,产生雾滴的索特平均直径平均增大了15%。此外,喷雾流量还与旋流槽数量成比例,旋流槽的螺旋角主要影响喷雾角。喷嘴入口处的流体相对压强则对喷雾角及雾滴粒径有较大的影响,其中喷雾角随着相对压强的增大而增大,而雾滴的索特平均直径随压强的增大呈非线性递减,当流体的相对压强从70增大至160 k Pa时,系列化旋流喷嘴的索特平均直径降低了约25%~35%。此外对于旋流喷嘴而言,流体黏度的增大会导致喷雾角的减小,但适当增加流体的黏度（不超过纯水黏度的200%）可显著降低雾滴的平均粒径,提高喷嘴的雾化质量。该研究可为农用无人机超低容量变量喷洒系统的研发提供参考。

英文摘要：

The ultra-low-volume precision spraying of agricultural UAV（unmanned aviation vehicle） is a key technology in the field of plant protection. There are still some problems in the application of the ultra-low-volume spraying of agricultural UAV in China, such as relatively large droplet diameter of hydraulic nozzle, complex centrifugal nozzle structure and high price. Based on the mechanism of swirl atomization and the modular approach, a new swirl nozzle is developed in this paper. The hydrodynamics and the atomization characteristics of the flow field in the nozzle are studied numerically and experimentally. The physical properties of the fluid and the effect of the atomizer geometry on the atomization characteristics are obtained. The results show that the breakup of conical liquid sheet occurs via unstable growth of sinuous waves on the surface of the liquid sheet. In the structural parameters of the swirl nozzle, the diameter of the nozzle orifice has a great effect on the atomizer performance. As the diameter of the nozzle orifice increases from 1 to 1.5 mm, the average flow rate of the spraying is increased by 46.23%. At the same time, the average of spray angle is increased by 29.77% and the SMD（Sauter mean diameter） is increased by 15%. In addition, the flow rate of the spraying is linearly proportional to the number of the swirl slots. The spray angle is also impacted by the inclination angle of the swirl slot. When the inclination angle is increased from 30° to 45°, the spray angle is reduced by 11.6%. The relative flow pressure on the nozzle inlet has a significant impact on the flow rate of the spraying and the diameter of the droplet. The flow rate of the spraying linearly increases with the relative flow pressure, while the Sauter mean diameter decreases nonlinearly with the relative flow pressure. The experiments indicate that the Sauter mean diameters of serial swirl nozzles decrease by 25%-35% with an increment in the relative flow pressure from 70 to 160 k Pa. In order to achieve the va