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基于闸堰联调的明渠水力特性与流量调控模型

Hydraulic characteristics and flow regulation model of open channel based on the joint regulation of gate and weir

  • 摘要: 针对西北干旱地区明渠灌溉过程中下游流量调控不精准造成水资源利用率低、农作物减产等问题,该研究提出一种基于闸堰串联的明渠流量调控方法。首先通过对明渠中闸门与堰的水力特性和流量公式进行理论分析,结合FLUENT流体仿真与单因素试验探明了影响闸堰联调下明渠流量的关键参数为闸前水位、闸前流速、闸门开度和堰前水位,且闸前水位、闸前流速和闸门开度与下游流量呈正相关,而堰前水位与下游流量呈负相关。进一步探究因素间交互作用并构建精准流量调控模型,选取上述4个关键参数为试验因素,以下游流量为评价指标,开展box-behnken design(BBD)响应面试验。仿真试验结果表明,闸门开度与闸前水位、闸门开度与堰前水位的交互项对下游流量影响显著,增加闸门开度和闸前水位,降低闸前流速和堰前水位,可提高下游液位和流量的稳定性;基于响应面建立的明渠流量调控模型相关系数R2=0.9905,具有较好的预测精度。最后通过对现有手动闸门进行自动化改造,搭建了用于明渠流量调控的田间试验平台。田间试验结果表明,基于闸堰联调的明渠流量调控模型控制误差小于12%。研究可为灌区明渠流量调控提供思路。

     

    Abstract: Open channel water conservancy control components, especially gates and weirs, are widely used in most Chinese irrigation areas. They are important tools for water distribution and flow regulation, and play a crucial multifaceted role in improving the efficiency and effectiveness of agricultural irrigation systems and optimizing water resource management. In response to the inaccurate flow regulation of downstream flow in open channel irrigation in the arid areas of the northwest, resulting in low water resource utilization and crop yield loss, this paper proposes to control downstream flow through joint regulation of gates and weirs. First, through theoretical analysis of the hydraulic characteristics and flow formulas of gates and weirs in open channels, combined with FLUENT fluid simulation and single-factor experiments, it is found that the key parameters affecting the flow rate of open channels under joint gate - weir regulation are water level before gates, flow velocity before gates, and water level before weirs. The water level before gates, flow velocity before gates and gate opening are positively correlated with downstream flow, while the water level before weirs is negatively correlated with downstream flow. In terms of simulation model construction, a three-dimensional model of open channels, gates and weirs was established using SolidWorks. In FLUENT fluid simulation software, the simulation model is established using the SST k-ω turbulence model and the VOF multiphase flow model. In order to explore the interaction between factors and build a precise flow regulation model, the water level before gate, velocity before gate, water level before gate, and the water level before weir were selected as the test factors, and the flow rate in the downstream is used as the evaluation indicators, and the box-behnken design (BBD) response surface test of the four factors and three levels was carried out. After 29 simulations under different parameters, the simulation test results show that the increase of gate opening and water level before gate under the control of gate weirs, the decrease of the flow velocity before gate and water level before weir makes the downstream flow velocity and liquid level more stable and the flow rate is more stable. The results of the variance analysis show that the water level before gate, velocity before gate, gate opening, water level before weir have a significant impact on flow rate; the correlation coefficient R2=0.9905 established open channel flow regulation model has good prediction accuracy. The response surface analysis shows that the water level before gate, flow velocity before gate, and water level before weir have a significant impact on the flow rate. Specifically, the interaction terms between the water level before gate and the gate opening, as well as the water level before weir and gate opening, will also have a significant impact on the flow rate. Finally, through the automated transformation of the existing manual gates, a field test platform for open channel flow regulation was built to realize automatic gate control, reducing the experimental error of manual operations. The field test results show that under the joint adjustment of the gate and weir, the relative error between the model predicted flow and the actual flow is less than 12%. The finding can provide ideas for the regulation of open canal flow in irrigation areas.

     

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