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This paper presents an experimental study on thedevelopment of an efficient energy dissipator ascompared to Garde's energy dissipator (Garde et al.1986) for pipe outlets. The recommended designs werelaboratory tested on scale models with pipe outletdiameter of 10 cm and 7.5 cm for Froude number rangingfrom 1.70 to 5.50. The performance of the newdissipator improved tremendously by using new shapes,sizes and locations of the appurtenances for the samelength of stilling basin. This was possible due tobetter spreading of efflux jet by using a propersplitter block. The formation of a strong vortexinfront of the solid impact wall, in place of a grid,and an additional horizontal shear at the bottomproduced more fine grained eddies and turbulence,which finally reduced the energy of the outgoing flow. The low bottom velocities at the end of the basinresulted in reduction of the scour. The performanceof various models has been compared by estimating thescour index based on maximum depth of scour and itslocation at the end of run time. 相似文献
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An experimental work leading to the development of economical and improved stilling basin designs for circular pipe outlet
in comparison to Garde's stilling basin [Garde, R.J. & Saraf, P.D., Journal of Irrigation and Power 1986, 145–154], is reported
in this paper. In the present study, attempts are made to develop efficient and shorter stilling basin models keeping the
basin floor at the invert level of the pipe outlet for inflow Froude number Fr = 5.50. The new designs are arrived at by conducting
a systematic experiments on the stilling basin models having appurtenances like a wedge-shaped splitter block, a modified
grid, an intermediate sill and a rounded step. Scour index, a non-dimensional number has been defined to compare the performance
of the stilling basin models using the same erodible material and time of experimental run. The performance of the newly developed
stilling basin models has been compared with that of Garde's stilling basin model G-D∗. The proposed model M is also compared with the earlier stilling basin model M-12, as suggested by Goel & Verma [Journal
of Irrigation and Drainage Systems 15(1), 2001, 81–91]. 相似文献
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为了提高现行规模化滴灌工程系统的经济性、操作性和机械化水平,本文以支管长短管布置形式代替等距布置对现有滴灌支管轮灌模式下管网的布置进行改进研究。结果表明:支管长短管布置形式减少了大口径管材管件用量和地埋管路的长度,平均每公顷可减少管网成本和土方工程费用分别为202.5元和37.5元;管网布置形式改进后,田间出水管相对集中,分布密度减少一半,同时可节地约0.3%。此外,改进管网布置形式有利于减少管网工程施工的工作量和管材的损耗量,且管网结构更便于施工。因此,长短管布置形式是更适合于滴灌支管轮灌模式的管网布置形式,可应用于规模化滴灌工程。 相似文献
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【Objective】 This paper aims to study the optimal layout of inclined pipes in sedimentation basins in attempts to improve sediment removal efficiency in the Yellow River. 【Method】Three different layouts of inclined pipes were compared: a single layer (Fs), and two double-layer layouts (Fv1, Fv2), in a gravity-operated sedimentation basin. Sediment distribution of three typical particle sizes in the upstream (Su), middle stream (Sm), and downstream (Sd) was measured. Sediment tests were conducted under a low (Qq) and a high (Qs) flow rate to compare the impact of pipe inclination on sedimentation in the three layouts. 【Result】The large granular sediment settled prior to entering the inclined pipes, while the fine particle sediment (<75 µm) was effectively captured by the inclined pipe. These resulted in an outlet sediment content of 0.342~1.354 kg/m3 and a sand content of 0~0.018 kg/m3. Among the different inclined pipe layouts, Fv2 exhibited the lowest sediment and related sand, silt, and clay content at the outlet, followed by Fv1 and Fs. The Fv2 effectively controlled the outlet sediment content at 0.342~0.991 kg/m3, showing a reduction of 10.01%~20.95% and 26.82%-38.83%, compared to Fv1 and Fs, respectively. Furthermore, different Yellow River sections showed variations in sediment content, with the Su section exhibiting the lowest sediment and related sand, silt, and clay content. 【Conclusion】The sediment treatment capacity varied significantly among the three inclined pipe layouts for different Yellow River sediments (P<0.05). The V-shaped inclined pipe layout was superior to the conventional layout, with the Fv2 (inclination angles of 60° and 45°) being most effective. © 2023 Office of Journal of Irrigation and Drainage, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences. All rights reserved. 相似文献
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活塞式计量泵出口管道直径的大小直接影响着包装质量和包装效率,通常采用试验的方法找出合适直径的管道,不但浪费大量不锈钢管材,而且费时费力。经过理论推导和在试验基础上合理简化,得出了包装机粘稠物料断流管径理论数学模型。通过试验验证,该模型具有比较高的精度。 相似文献
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地下滴灌系统灌溉精准,能最大限度地满足植物对水分和养分的需求,是目前较为合理的灌溉形式之一。对国内外地下滴灌技术的研究现状进行调研与分析,探讨国内外对田间滴灌管网进行设计与优化的历程和方法,为我国推广应用地下滴灌管网技术提供有益的参考。 相似文献
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测定了5种排水暗管外包材料(麦秸秆、锯末、陶粒、沸石、纤维球)的透水特性,并分析了不同外包材料及其厚度的去氮效果。结果表明,各外包材料对氨态氮和硝态氮的去除能力存在差异,无机材料对氨态氮的吸附能力较强,有机材料对硝态氮的去除能力更好;10cm厚度时锯末除氮效果最好,去除率为55.1%,而在30cm厚度时沸石相对更好,去除率为76.2%;外包料的厚度对总氮的去除能力呈正相关关系,每增加10cm厚度,麦秸秆和锯末总氮去除率增加6%~8%,陶粒和沸石总氮去除率增加6%~28%,纤维球总氮去除率增加10%~20%。 相似文献
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暗管排水对油葵地土壤脱盐及水分生产效率的影响 总被引:5,自引:1,他引:5
为了建立宁夏惠农区庙台乡给予太阳能水泵抽水的暗管排水工程的灌溉排水制度,以油葵为研究对象,设暗管排水和非暗管排水2个处理,观测分析了暗管排水对田间土壤含盐量、地下水位和产量等的影响。结果表明,在油葵生育期内,与进行暗管排水前相比,暗管排水使暗管排水区的地下水水位降低0.09 m,降幅6.21%;地下水矿化度降低9.79%;土壤含盐量降低13.64%;与非暗管排水区相比,暗管排水区的油葵增产8.10%,灌溉水生产效率增加8.40%,群体水分生产效率增加9.86%。 相似文献
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太阳能暗管排水对银北灌区油葵土壤环境及产量影响 总被引:2,自引:0,他引:2
针对土壤盐渍化严重影响了宁夏银北灌区土壤环境和作物产量的问题,通过太阳能暗管排水区和非暗管排水区对比试验方法,着重研究了2017和2018两年太阳能暗管长时间持续排水对土壤环境和油葵产量的影响。结果表明:太阳能暗管排水可以有效改善土壤环境,使两年的地下水平均埋深分别增加4.5%和6.4%,地下水平均矿化度分别降低7.9%和9.0%,两年土壤平均脱盐率分别为4.7%和8.2%,对表层土壤的脱盐效果最为明显。同时提高了油葵产量和水分生产效率,两年油葵产量分别提高13.8%和21.6%,灌溉水分生产效率分别增加13.3%和21.8%,作物水分生产效率分别增加16.4%和22.9%。综合试验结果和经济成本考虑,油葵生育期灌水2次、播前灌水1次、冬灌1次,生育期5-9月持续排水,这是适宜惠农当地太阳能暗管排水条件下油葵的灌排制度。 相似文献
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本文对低压管道输水灌溉环状管网的经济性进行了分析研究,得出对集中轮灌的井灌区,在一定条件下环状管网优于树状管网的结论,推导出单环和双环管网流量分配系数公式和经济管径的通用计算公式。 相似文献
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以管网系统年费用最小为目标函数,水泵扬程H和连续管径D为设计变量,建立了确定性的泵站加压灌溉管网优化设计模型,并应用Excel规划求解法对所建立的模型进行了求解。实例表明,在管网布置形式已知的情况下,与传统的经济流速法相比,Excel规划求解法是一种实用价值较高的模型求解方法,该方法不仅能够节省一定的工程投资,还提高了设计人员的设计水平和效率。 相似文献