中文摘要：

为了提高机组喷洒均匀性、降低对土壤作物的打击强度，近几年国内圆形喷灌机逐渐安装低压阻尼旋转喷头，以替代非旋转低压喷头。本文采用面粉法对R3000和A3000低压阻尼喷头在安装3种喷嘴（直径为2．98、4．96和6．95mm）和2种工作压力（100和140kPa）下的水滴直径分布规律进行了试验，分析了水滴平均直径和总体水滴直径分布，探讨了水滴直径与喷头转速、喷嘴直径及工作压力的关系。结果表明，在相同工作压力和喷嘴直径下，A3000喷头转速要快于R3000喷头，但射程和末端水滴直径均有所减小。在相同喷嘴直径下，两种喷头随着工作压力的增大，射程均有所增大，但末端水滴直径呈变小趋势；在相同工作压力下，随着喷嘴直径增大，喷头射程均呈增大趋势，但末端水滴直径变化不显著。A3000喷头总体水滴直径分布范围比R3000喷头窄，不同工况下测得的A3000喷头水滴中数直径比R3000喷头小3．6％-8．9％。两种喷头径向不同位置处的水滴平均直径与喷头距离呈指数关系，中数直径随工作压力增大或喷嘴直径减小而变小。

英文摘要：

In order to improve coefficient of water distribution uniformity and lessen impact force of droplet on the soil and crops, low-pressure damping rotating sprinklers have been gradually applied on the center pivot irrigation systems in recent years, instead of non-rotating sprinklers. In this study, droplet size distri-butions of low-pressure damping of R3000 and A3000 sprinklers with three nozzles （diameters of 2.97, 4.96 and 6.95 mm, respectively） were measured with the flour method at two operating pressures of 100 and 140 kPa. The mean diameter of spray droplets and the overall droplet size distributions were calculated for each scenario. The effects of rotating speed, nozzle diameter and operating pressure on the droplet size were also analyzed. The results show that in comparison with the R3000 sprinkler at the same nozzle size and operating pressure, the A3000 sprinkler rotates faster, with a smaller spraying range and maximum droplet diameter. The spraying ranges of the two sprinklers increase with nozzle diameter. The maximum droplet diameter decreases with the increase of operation pressure. At the same operation pressure, the spraying ranges of the two sprinklers tend to increase with nozzle diameter, but the maximum droplet diame- ter does not change significantly. The A3000 sprinkler droplet diameter distribution is narrower than the R3000 sprinkler. The median diameters of A3000 sprinkler are 3.6 %-8.9 % smaller than the R3000 sprin-kler in different conditions. In addition, the mean diameter of the spray droplet is exponentially fitted with the distance from the sprinkler, and the median diameter becomes smaller as the operating pressure in- creased or the nozzle diameter decreased.