圆柱式滴头内镶及外包对滴灌毛管水力特性影响的模拟研究

目的 研究圆柱式滴头镶嵌方式对滴灌毛管水力特性的影响。方法 对2种内镶式滴灌毛管和1种外包式滴灌毛管进行灌水试验，同时采用计算流体动力学(Computational fluid dynamics, CFD)方法对3种滴灌毛管进行数值模拟并验证。在此基础上，对不同滴头流量下内镶式及外包式滴灌毛管水头损失及铺设长度进行模拟计算。结果 滴头内镶式及外包式滴灌毛管总水头损失模拟值略低于实测值，滴头外包式滴灌毛管模拟值与实测值相对偏差较小；滴头镶嵌方式对滴灌毛管水力特性影响显著，滴头外包式滴灌毛管相较滴头内镶式滴灌毛管总水头损失较小，总水头损失减小比例超过49.2%，且随滴头流量增加总水头损失减小比例逐渐增大；滴头外包式滴灌毛管最大铺设长度较滴头内镶式滴灌毛管更长，长度增加了21.6%~56.9%；滴头内镶式滴灌毛管总水头损失相对更大的主要原因是断面流速再分布引起压力梯度急变消耗了大量水流能量。结论 滴头外包式滴灌毛管水力性能优于滴头内镶式滴灌毛管，对于长距离经济作物滴灌系统设计，可优先考虑滴头外包式滴灌毛管。

Simulation study on the influence of trickle laterals equipped with integrated in-line and out-line emitters on the hydraulic characteristics

Objective To study the influence of emitter mosaic mode on the hydraulic characteristics of trickle laterals.Method Two kinds of trickle laterals equipped with integrated in-line emitters and one trickle lateral equipped with integrated out-line emitters were tested. At the same time, three kinds of trickle laterals were simulated and verified by computational fluid dynamics (CFD) method. On this basis, the head loss and laying length of trickle laterals equipped with integrated in-line and out-line emitters under different discharge were simulated and calculated.Result The simulated values of the total head loss of trickle laterals equipped with integrated in-line and out-line emitters were slightly lower than the measured values, and the relative deviation between the simulated and measured values of trickle laterals equipped with integrated out-line emitters was smaller. The drip head embedding mode had a significant influence on the hydraulic characteristics of trickle laterals. Compared with trickle laterals equipped with integrated in-line emitters, the total head loss of trickle laterals equipped with integrated out-line emitters was smaller, with the reduction ratio of the total head loss exceeding 49.2%, and the reduction ratio of the total head loss gradually increased with the increase of the drip head flow. The maximum laying length of trickle laterals equipped with integrated out-line emitters was longer than that of trickle laterals equipped with integrated in-line emitters, and the length increased by 21.6% to 56.9%. The main reason for the greater total head loss of trickle laterals equipped with integrated in-line emitters was that the pressure gradient of trickle laterals equipped with integrated in-line emitters consumes a large amount of water flow energy due to the redistribution of the flow velocity in the section.Conclusion The hydraulic performance of trickle laterals equipped with integrated out-line emitters is better than that of trickle laterals equipped with integrated in-line emitters. For the design of long distance economic crop drip irrigation system, trickle laterals equipped with integrated out-line emitters can be given priority.