积石峡电站灌溉引水系统模型试验及数值模拟

发布时间：2019-04-10 19:49

【摘要】：我国水资源短缺，降水在时间和空间上分布不均，近年来工农业迅速发展，供水需求逐渐增大，加上现存的水资源污染和水资源过度开发，加剧了水资源供需矛盾。水资源已经成为制约人类生存和社会可持续发展的瓶颈因素。为缓解这种现状，国家投入大量的财力、物力开展长距离调水工程，重力流输水因具有节约能源的特性得到广泛的应用，在条件允许的情况下成为长距离输水工程的首选方案。本文针对积石峡电站灌溉引水系统输水管网所涉及的输水能力验证、异型岔管局部水头损失、水锤防治措施等问题进行了相关的模型试验、数值模拟及分析计算，为本工程设计阶段相关技术参数的确定以及工程建成后的合理运行提供了科学指导，相关成果可为同类工程建设提供参考依据。通过对输水主管线岔管节点附近上下游局部正态模型模拟以及管线其余部位概化模拟相结合的模型试验研究手段对各工况下的供水情况进行了研究。模型试验结果表明：积石山单独运行、民和县单独运行、积石山与民和县同时运行三种不同运行方式局部水头损失系数在不同流量时基本稳定；不同特征水位下，各供水形式管网的输水能力均能满足设计要求，，设计方案可行。在模型验证基础上，应用三维数值模拟研究岔管处水流形态及局部水头损失系数，计算结果表明：各工况下得到的局部水头损失系数与模型试验值最大差值百分比为14.45%，两者相差较小；单管供水工况水流形态优于双管供水，积石山方向参与供水时岔管处产生较大漩涡，水头损失较大。基于物理模型及数值模拟对岔管处局部水头损失系数的研究结果开展供水管线的水力计算，确定各管段的压力分布情况，各特征水位下管道末端水压在下游库区水位处上下浮动，且两者差值在误差范围以内，证明供水系统能够达到供水能力的要求。通过理论分析重力流输水系统的水击产生机理、水击防护技术，在前人对水击防护措施实施效果研究的基础上，类比同类工程，提出了在已有设计方案（安装排气阀）的基础上增设箱式双向调压塔或者减压泄压阀的水击防护措施。
[Abstract]:The shortage of water resources in China, the uneven distribution of precipitation in time and space, the rapid development of industry and agriculture in recent years, the increasing demand for water supply, and the existing water pollution and over-exploitation of water resources, aggravate the contradiction between supply and demand of water resources. Water resources have become a bottleneck factor restricting human survival and social sustainable development. In order to alleviate this situation, the state has invested a lot of financial resources and material resources to carry out long-distance water transfer projects. Gravity flow water transfer has been widely used because of its energy-saving characteristics, and has become the first choice for long-distance water transfer projects under conditions permitting. In this paper, the model test, numerical simulation, analysis and calculation are carried out for the problems related to the water transportation capacity verification, local head loss of special-shaped bifurcation pipe, water hammer prevention measures and so on in the irrigation and diversion system of Jishi Gorge Power Station. The scientific guidance is provided for the determination of the relevant technical parameters in the design phase of the project and the reasonable operation of the project after completion, and the related achievements can provide reference basis for the construction of the same kind of projects. In this paper, the local normal model simulation of upper and lower reaches near the bifurcation joint of main line of water transmission line and the model test method of generalizing other parts of pipeline are used to study the water supply under various working conditions. The results of model test show that the local head loss coefficient of Jishi Mountain and Minhe County is basically stable when the discharge is different, and the local head loss coefficient of Jishi Mountain and Minhe County is basically stable when the operation mode is separate and Minhe County is running alone, and the local head loss coefficient is stable at the same time. Under different characteristic water level, the water carrying capacity of each water supply network can meet the design requirements, and the design scheme is feasible. Based on the model verification, the three-dimensional numerical simulation is applied to study the flow pattern and the local head loss coefficient at the bifurcation pipe. The calculated results show that the maximum difference percentage between the local head loss coefficient and the model test value is 14.45% under various working conditions. The difference between them is small; The flow pattern of single-pipe water supply is better than that of double-pipe water supply. When the direction of Jishi-shan is involved in the water supply, there is a large vortex at the bifurcation pipe, and the loss of water head is greater. Based on the physical model and numerical simulation, the hydraulic calculation of the water supply pipeline is carried out to determine the pressure distribution of each pipe section, based on the results of the study on the local head loss coefficient at the bifurcation pipe. Under the characteristic water level, the water pressure at the end of the pipeline fluctuates up and down in the downstream reservoir area, and the difference between the two is within the error range, which proves that the water supply system can meet the requirements of the water supply capacity. Through the theoretical analysis of the water hammer generation mechanism of gravity flow water conveyance system, the water hammer protection technology, on the basis of previous research on the effect of water hammer protection measures, similar to similar projects, Based on the existing design scheme (installation of exhaust valve), the water hammer protection measures of adding box type bi-directional surge tower or pressure relief valve are put forward.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV67;TV131.6

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