喷头不同组合模式下水量分布和喷灌均匀度的田间试验及数值模拟

Field test and numerical simulation of water distribution and sprinkler irrigation uniformity under different combination modes of sprinklers

利用三次样条两次插值叠加法并结合单喷头水量分布可计算得到多喷头组合水量分布。为验证该方法的适用性及探究变间距条件下喷灌均匀度的变化情况,通过田间试验,得到ZY-2型单喷头水量分布及多喷头18 m×18 m组合形式下水量分布,计算了喷灌均匀度。利用MATLAB软件构建了喷头组合条件下水量分布的数值模拟模型,计算出不同组合模式下水量分布和组合喷灌均匀度。结果表明:模拟与实测喷灌水深的相对误差(RE)和均方根误差(RMSE)分别为8.49%和3.17 mm,组合喷灌均匀度的相对误差为1.85%,表明构建的模型能较准确地模拟不同喷头组合条件下的水量分布和组合均匀度;ZY-2型喷头在正方形21 m×21 m布置形式下,喷灌均匀度达到最高(0.873);在变喷头间距和变支管间距两种矩形布置时,喷灌均匀度整体上随着支管间距的增加而逐渐降低,但喷头间距增加时喷灌均匀度降低的幅度更大。研究结果可为优化喷头布置形式提供技术支撑。

The water distribution under the condition of combined sprinklers can be calculated using the combination of cubic spline and double interpolation superposition method and the water distribution of a single sprinkler. This study aims to verify the applicability of this method and investigate the changes of sprinkler irrigation uniformity with variable spacing between sprinklers and laterals. Through field experiments,the water distribution of a ZY-2 type sprinkler and the 18 m × 18 m combination mode was measured,and the corresponding water distribution uniformity was calculated. A numerical simulation model was developed using MATLAB to calculate water distribution and irrigation uniformity under the condition of different sprinkler combinations. The results show that the relative error and RMSE of simulated and measured sprinkler irrigation depth are 8. 49% and 3. 17 mm,respectively,and the relative error of the irrigation uniformity for the combined sprinkler mode is 1. 85%. This indicates that the model can accurately simulate the water distribution and irrigation uniformity under different sprinkler combinations.The simulation results show that sprinkler combination mode of 21 m × 21 m for the ZY-2 sprinklers has the highest irrigation uniformity( 0. 873). Increasing the spacing of sprinklers and laterals can reduce the sprinkler irrigation uniformity;however,the uniformity decreases more when the nozzle spacing increases. The research results are expected to provide technical support for optimizing the layout of sprinklers.