坡地喷灌水滴直径与动能强度分布规律研究

在室内无风条件下应用视频雨滴谱仪实时监测了不同坡度下喷洒水滴直径和速度等信息,研究了不同坡度下水滴平均直径及直径频率沿射程方向的变化规律,分别建立了水滴平均直径、速度与坡度等之间的数学关系。以此为基础,结合坡地喷灌水量分布计算方法,提出了无风条件下坡地喷洒水滴动能强度计算模型,并通过试验验证了该模型的正确性。以雨鸟LF1200型喷头为研究对象,应用该模型重点分析了不同喷头布置方式、间距和坡度对组合喷头打击动能强度分布的影响。结果表明:随着喷头间距的增大,动能强度分布越来越不均匀,且动能强度高值区所占比例不断减小;坡度变化对坡面动能强度分布影响并不明显;三角形布置方式对减小坡地喷灌打击动能强度具有一定作用。同时考虑打击动能强度和水量分布,在坡地喷灌系统设计时,若选用雨鸟LF1200型喷头,建议优先采用三角形布置,且间距为0.8倍的平地喷头射程。

Droplet Diameter and Kinetic Energy Intensity Distribution Regularities for Sprinkler Irrigation on Sloping Land

The diameter and velocity of spray droplet on different slopes under no wind were measured by two-dimensional video disdrometer. The change regularities of average droplet diameter and its cumulative frequency along spray direction under different slopes were studied. The relationship between the average droplet diameter, velocity and slope were established. Based on the calculation method of water distribution, the model for calculating droplet kinetic energy intensity distribution of sprinkler irrigation on sloping land without wind was proposed. The model was validated by experiment. The Rainbird LF1200 sprinkler was selected as the research object, and the influences of sprinkler layout, spacing and slope on the kinetic energy intensity distribution of combined sprinkler were mainly analyzed by the model. The results showed that droplet kinetic energy intensity distribution uniformity and the proportion of high value area of kinetic energy intensity were both decreased as the sprinkler spacing was increased. The effect of slope on kinetic energy intensity distribution was insignificant. Layout of sprinklers with triangular lattice was useful to decrease kinetic energy intensity of the sprinkler on sloping land. If the Rainbird LF1200 sprinkler was used for designing sprinkler irrigation system on sloping land, the sprinkler spacing was recommend as 0.8 times of the spraying range on flat ground with the triangular lattice layout, considering the impact of kinetic energy intensity and water distribution simultaneously.