基于流量对泥沙沉积敏感度的滴灌灌水器水力性能动态评价

提出了基于流道泥沙沉积过程的滴灌灌水器水力性能动态评价方法,以反映灌水器浑水流量对其进口压力变化和泥沙沉积过程的敏感程度。以3种双向流道灌水器和1种迷宫式流道灌水器为研究对象,在3种进口压力下,分别进行清水和浑水试验。结果表明,迷宫式流道灌水器流态指数浑水条件下相比清水增大74.85%,1#,2#和3#双向流道灌水器分别增大38.47%,41.26%,46.25%,流道中泥沙的沉积使其水力性能变差;双向流道灌水器浑水流态指数均小于迷宫式流道灌水器;随着浑水试验次数的增加,4种灌水器浑水流态指数总体趋势是逐渐增大,成因是流道中泥沙沉积的累积效应,反映了浑水条件下水力性能的动态变化过程;相同压力变化,浑水条件下迷宫式流道灌水器流量变化率比清水时增大40.43%,1#,2#和3#双向流道灌水器分别增大17.23%,19.43%,22.33%,迷宫式流道灌水器增大程度大于双向流道灌水器,导致其水力性能相对双向流道灌水器下降较大;4种灌水器水力性能与抗堵性能差异均显著,且双向流道灌水器的水力性能与抗堵性能均优于迷宫式流道灌水器,说明灌水器流道结构形式及结构参数是影响灌水器整体性能的重要因素。

Dynamic response evaluation of hydraulic performance based on sediment deposition sensitivity to flow rate of dripper emitter

Abstract: The performance of dripper irrigation emitter is of great concern in the emitter design and use. Generally, there are two important methods to estimate the performance of dripper emitters: their hydraulic performance and their anti-clogging performance. The hydraulic performance is always calculated in rinsing experiments; but in practice, although deposition and filtration techniques are adopted, fine sand particles can still penetrate into dripper emitters. This may change the forms and roughness of the flow channel. As a result, the hydraulic performance of dripper emitters in the field may greatly differ from initial rinsing tests. In addition, inlet pressures of dripper emitters may differ with different position in the field pipe network because of the influence of the topographical height difference and the head loss. So it is not particularly accurate to use the decrease in the rate of discharge under a fixed working pressure as usual to estimate the anti-clogging performance of dripper emitter. In order to overcome this discrepancy, we proposed a method to estimate the performance of dripper emitters that accounted for the influence of inlet pressure changes and sediment deposition on their hydraulic performance. We selected 3 bidirectional flow channels and 1 labyrinth channel for our study. Rinsing experiments were carried out at 50, 75, and 100 kPa to calculate the flow index of the dripper emitters. Periodic intermittent drip irrigation tests were also carried out to measure the changes of flow discharge using muddy water containing sediment particles with different sizes (all less than 0.125 mm); the sediment particles were formulated to 30 g/L of muddy water. The results showed that the flow indexes of selected dripper emitters in the muddy water experiment were bigger than the values in the rising experiment. This means that the hydraulic performance of the 4 types of dripper emitters got worse, which indicated, not surprisingly, that sediment deposits worsened the hydraulic performance. The increase in flow rates of No.0, No.1, No.2, and No.3 dripper emitters were 74.85%, 38.47%, 41.26%, 46.25%, respectively. After the muddy water experiment, the hydraulic performances of the bidirectional flow channels were still better than the contrastive labyrinth channel because the anti-clogging performance of bidirectional flow channels were better. The hydraulic performance of the 4 types of dripper emitters got worse and worse as muddy water irrigation frequency increased, which indicated that the larger the cumulative effect of sediment deposition could result in the greater influence on hydraulic performance. When the inlet pressure increased from 50 kPa to 100 kPa, the rates of discharge changes of No.0, No.1, No.2, and No.3 dripper emitters in the muddy water experiment were 40.43%, 17.23%, 19.43%, 22.33% higher than those in the rinsing experiment. The sensitivity of discharge to inlet pressure changes of the 4 types of drip emitters got bigger, which caused the hydraulic performance to drop. There were significant differences in hydraulic performance and anti-clogging performance among the bidirectional flow channels with different structural parameters; this indicated that structural parameters were the main factors affecting the overall performance of dripper emitters. Our method, using the dynamic response of hydraulic performance to sediment deposition in muddy water irrigation to evaluate the overall performance of dripper emitters, can improve dripper emitter development and provide a method guidance for measuring the overall performance of dripper emitters.