平地向坡地转换喷灌水量分布计算模型研究

针对坡地喷灌水量分布实测困难问题,以坡地喷头射程计算公式为基础,依据喷头射流方向总水量守恒原理,构建了喷灌水量分布由平地转换到坡地的计算模型,并通过试验验证了模型的正确性。利用该模型,分析了喷头布置方式、喷头间距、工作压力和坡度等对坡面喷灌水量分布的影响,结果表明,三角形布置有利于坡地单喷头水量分布的叠加,且其组合喷灌均匀度略高于方形布置;随着喷头间距的增大,组合喷灌均匀度呈下降趋势;喷头低压运行时,组合喷灌均匀度相对较低,不能满足喷灌均匀性的要求,随着喷头工作压力的增大,组合喷灌均匀度逐渐增大;在一定坡度范围内,不同坡度对水量分布和组合喷灌均匀度的影响较小。因此,在坡地喷灌系统设计时,若选用雨鸟LF1200型喷头,建议采用三角形布置,喷头间距宜为1.0~1.2倍平地喷头射程,喷头工作压力宜选用300 k Pa。

Calculated Model for Transforming Sprinkler Water Distribution from Flat Ground into Sloping Land

It is difficult to measure water distribution for sprinkler irrigation on sloping land. Based on the formula for calculating sprinkler range on sloping land, according to the principle of water balance along spray direction, a calculated model for transforming sprinkler water distribution from flat ground into sloping land was proposed and validated by an experiment. The effects of sprinkler layout, sprinkler spacing, operating pressure and slope on sprinkler water distribution on sloping land were analyzed by using the model. The results showed that water distribution for the sprinkler triangular arrangement was more uniform than that for square layout, and the combined sprinkler irrigation water application uniformity for the sprinkler triangular arrangement was slightly higher than that for square layout. The combined sprinkler irrigation water application uniformity was decreased with the increase of sprinkler spacing. When the sprinkler was operated at low pressure, the combined sprinkler irrigation water application uniformity was relatively low, and the low uniformity cannot meet the requirement of sprinkler irrigation uniformity. The combined sprinkler irrigation water application uniformity was increased with the increase of sprinkler pressure. The effect of slope on water distribution and the combined sprinkler irrigation water application uniformity was insignificant within a certain slope. Therefore, if the Rainbird LF1200 sprinkler was used in the sprinkler irrigation system design on sloping land, it was recommended that the sprinkler spacing should be 1.0~1.2 times as the spraying range on flat ground with the triangular arrangement, and the sprinkler operating pressure should be 300kPa.