滴灌系统叠片过滤器结构参数优化

    Optimization of structural parameter for disc filter in drip irrigation system

    • 摘要: 针对不同级配含沙水和灌水器类型的叠片过滤器结构选型问题,该研究选取常用叠片过滤器,通过组合不同叠片数量改变相邻叠片间孔径,设计了多种不同泥沙处理能力的过滤器。对5种泥沙粒径级配条件下5种孔径叠片过滤器的性能开展试验研究,根据不同工况下叠片过滤器运行周期内的水头损失、堵塞时段水头损失增长速率、过滤器的堵塞均匀度以及灌水器流量偏差率等指标,采用模糊数学综合评价方法,构建综合考虑灌溉含沙水、叠片过滤器和滴灌灌水器的多目标评价模型。结果表明:基于叠片孔径可调的过滤器可以实现拦截不同粒径范围泥沙的目标,5种孔径过滤器拦截泥沙粒径(拦截率大于90%的沙粒段中最小粒径级配的中值粒径)分别为49、82、100、127和150 μm;随着过滤器孔径减小,粒径越细小的含沙水对水头损失增大作用越显著。不同级配含沙水和灌水器类型条件下叠片过滤器性能综合评价结果与试验结果相符,通过对综合评价指标值排序,筛选出灌溉含沙水、过滤器、灌水器三者最优的匹配方式,能够同时实现灌水器堵塞程度轻微和过滤器性能稳定。提出的叠片过滤器结构参数配置决策方案,可为叠片过滤器的合理配置和使用提供参考。

       

      Abstract: Disc filter has been widely applied in irrigation field, due to its better backwashing. However, the head loss of disc filter can sharply increase to the critical range in a short time. It is still lacking on the reasonable and scientific configuration of disc filter products, according to the different irrigation water and the emitter types. In addition, the existing products of disc filter cannot fully meet the requirements under the various irrigation water in drip irrigation. Even filtering has been abandoned in practical applications. As a result, the disc filters are seriously restricted. It is very necessary to select the suitable products of disc filter with the various structural parameters. This study aims to avoid the steep increase of the head loss for the high efficiency of filtering. Multiple disc filters were designed by adjusting the aperture between adjacent laminations. The optimal accuracy of filtering was obtained under the critical number of laminations. The hydraulic and filtering performance of the disc filter were evaluated under the sandy water with five grading levels of sand particle size. A systematic investigation was made to determine the growth rate of head loss in the clogging periods, the clogging uniformity of disc filters, and the discharge deviation rate of emitters under different operating conditions. A multi-objective evaluation model was constructed using fuzzy comprehensive evaluation (FCE), considering the different irrigation sandy water, disc filters and micro irrigation emitters. The results show that the disc filters with adjustable aperture between adjacent laminations were achieved in the filtering sand with the large ranges of sand particle size. Disc filter with five apertures intercept sand particle sizes were 49, 82, 100, 127, and 150 μm. The above mentioned particle size refered to the median particle size of the minimum particle size grading in the sand segment with an interception rate greater than 90%. The particle size was smaller in the sandy water, as the aperture of disc filter decreased, indicating the more significant increase in the head loss. There was the consistence between the comprehensive evaluation results and experimental performances of disc filter under the different irrigation sandy water and the emitter types. The comprehensive evaluation indexes were sorted to select the irrigation sandy water, the aperture of disc filter and the emitter type. The slight clogging was simultaneously obtained for the emitter and stable performance of disc filter under efficient operation in the entire irrigation system. The optimal structural parameters of disc filters can provide a strong reference for the rational configuration of disc filters. The finding can also offer new optimization design ideas for the adaptability of disc filters.

       

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