Numerical Simulation Of Spraying Water Depth Distribution And Water And Energy Saving Effect Of Piped Sprinkler Irrigation System

Aiming at the spatial and temporal variation characteristics of hydraulic elements of pumping stations,pipe networks and sprinkler heads during the irrigation rotation of piped sprinkler systems,a combination of theoretical analysis and numerical simulation is used to carry out numerical simulation of water depth distribution and water and energy saving effects of piped sprinkler systems in order to make the uniformity calculation results of piped sprinkler systems more in line with reality and to improve the effectiveness of piped sprinkler systems.The main research results are as follows:(1)Based on the dynamic characteristics of pumping station,pipe network and sprinkler head hydraulic elements and single sprinkler head water depth distribution model during the irrigation rotation of the piped sprinkler system,the actual water depth distribution of single sprinkler head is interpolated by the three-dimensional spline two-dimensional interpolation method,and the system water depth distribution model is constructed.When the side length of the water depth calculation grid is set to 0.5m and below,by the two nozzle spray water depth calculated by the water and the system water consumption relative error within 0.09%～2.99%,the model accuracy is high.(2)the use of nozzle water uniformity and system water depth uniformity as an evaluation index of irrigation quality,respectively,the main nozzle diameter of 6mm and the main nozzle diameter of 8mm ZY-2 nozzle combination uniformity study.The calculation results show that,under the same circumstances,the 6mm nozzle sprays less water,and the uniformity of nozzle water and system water depth is higher.(3)Based on the principle that the sum of the water sprayed by the sprinkler heads of each rotation group in the sprinkler system is equal,the concept of variable operating hours of the sprinkler system rotation group and the system water depth distribution and uniformity calculation model are proposed.Compared with the existing sprinkler irrigation system of equal running hours for each group,the variable running hours can save 2.38%～2.55%of water and 1.14%～1.18%of energy in the sprinkler irrigation system.(4)The numerical simulation scheme of variable operating hours for 16 groups of rotating irrigation groups was developed by using orthogonal experimental method with trunk pipe inner diameter,branch pipe inner diameter,branch pipe spacing and sprinkler head spacing as influencing factors.The ANOVA results showed that the factors influenced the uniformity of system water depth in descending order:branch pipe inner diameter,sprinkler spacing,trunk pipe inner diameter,and branch pipe spacing.The degree of impact on the water saving rate and energy saving rate in descending order:the inner diameter of the trunk pipe,branch pipe spacing,branch pipe inner diameter,nozzle spacing.(5)in order to simplify the calculation of the system water depth uniformity,nozzle spacing,branch pipe spacing,branch pipe diameter,trunk pipe diameter and nozzle water uniformity as the influencing factors,the construction of multiple regression model,the model for fixed operating hours and variable operating hours of the system water depth uniformity simulation effect is better,the coefficient of determination of the two models have reached 0.97,the standard error of 0.35 and 0.34,respectively.