滴头制造偏差对灌水均匀度及毛管造价的影响

Effect of emitters manufacturing variation of micro-irrigation on uniformity and lateral cost

为了阐明滴头制造偏差系数、灌水均匀度、毛管直径及毛管造价的内在联系,降低滴灌系统造价、提高灌水均匀度,通过理论推导结合实证计算的方法,系统分析了不同均匀度条件下滴头制造偏差系数极限值,以及滴头制造偏差系数、毛管直径、允许均匀度等三者的关系,并推导出毛管造价计算公式.结果表明:对于长度为100 m的毛管,当Keller均匀系数(EEU)为0.80时,制造偏差系数从0.05增大到0.07和0.11时,毛管造价分别增大8.7%和37.1%;当滴头制造偏差系数为0.03,EEU由0.80增大到0.85,0.90和0.95时,毛管直径分别增大20%,23.5%和56.5%,毛管造价也相应增大20%,53.8%和207.7%;当滴头制造偏差系数为0.05,EEU由0.80增大到0.85和0.90时,毛管直径则分别增大19.3%和32.8%,毛管造价也分别增大17.1%和71.4%;对于EEU为0.95时,毛管允许最小流量大于平均流量,管径计算无解.在限定值范围内,滴头制造偏差系数和Keller均匀系数的微小增大将直接导致毛管直径和造价急剧增大;滴灌系统设计应选择制造偏差系数小的滴头及合理的灌水均匀度,以达到降低工程造价的目的.

In order to find the relationship among the emitter manufacturing variation coefficient,the lateral cost and the lateral diameter,and to decrease the cost of drip irrigation engineering the allowable values of the emitters manufacturing variation coefficient are analyzed for different emission uniformity coefficients（EEU）.Then,the relationship among the esmitters manufacturing variation coefficient,lateral diameter,and the EEU is investigated.The function of the lateral cost is also parameterized.An application illustration shows that the pipe cost increases by 8.7% and 37.1% when the emitters manufacturing variation coefficients increase from 0.05 to 0.07 and 0.11,respectively,for the lateral length of 100 m and EEU of 0.80.When the EEU increases from 0.80 to 0.85,0.90 and 0.95,the lateral diameter increases by 20%,23.5% and 56.5% and lateral cost increases by 20%,53.8% and 207.7%,respectively,for the emitters manufacturing variation coefficient of 0.03.For the emitters manufacturing variation coefficient of 0.05,when EEU increases from 0.80 to 0.85,0.90,the lateral diameter increases by 19.3% and 32.8%,and lateral cost increased by 17.1% and 71.4%,respectively.In addition,when the EEU is 0.95,the hydraulic calculation cannot be performed,because the allowable hydraulic variation is negative.It is concluded that the lateral diameter and cost increase significantly with increasing the emitters manufacturing variation coefficient and the given uniformity coefficient.Furthermore,when the emitters manufacturing variation coefficient or the emission uniformity coefficient is larger than a preset value,the hydraulic design can not be carried out.