基于混合模型的管道输沙特性数值模拟研究  

Numerical simulation of sediment transport characteristics based on hybrid model

作　　者：李珊珊[1] 李国栋[1] 张大帅[1] 张巧玲[1] 秦毅[1] 

机构地区：[1]西安理工大学西北旱区生态水利工程国家重点实验室培育基地,陕西西安710048

出　　处：《西北农林科技大学学报（自然科学版）》2017年第1期225-234,共10页Journal of Northwest A&F University(Natural Science Edition)

基　　金：水利部公益性行业科研专项(201301063);陕西省自然科学基础研究计划项目(2015JM5201);国家自然科学基金项目(51579206)

摘　　要：【目的】探索管道水沙两相流的流场结构和输沙特性,为进一步研究管道输沙过程中阻力损失随含沙量、流速等的变化规律奠定基础。【方法】采用多相流混合模型和标准k-ε湍流模型,利用管道清水层流和湍流流场模拟,验证所选模型的可行性,并将模拟得到的管道流场以及阻力情况与实测值和计算值进行对比,确定模型参数,进一步结合小浪底水库现场管道抽沙试验,对管道流量(Q)为620和950m3/h工况下含沙量(Cv)分别为3.74%,10.53%,22.64%,37.74%和45.28%的5种含沙水流进行数值模拟计算,并分析其流场结构和流速、含沙量的垂向分布等水力特性。【结果】根据模拟值与实测值以及计算值的综合对比情况,选定粗糙度0.6mm、粗糙常数0.6、入口湍流强度25%为参数组合来模拟分析管道含沙水流的流动特性,得到了5种含沙量工况下管道输沙过程中的水沙两相流分布和管道横断面的流速分布,以及5种含沙量下横断面流速的垂向分布和含沙量的垂向分布规律,具体表现为:在管道流量Q=620和Q=950m3/h时,管道中心断面水沙呈上小下大的悬移质分布形态,随着水流含沙量的增加,管道底部沙量逐渐增大,当含沙量增加至45.28%时,管道中的水沙几乎为稠密的沙浆,在垂向分布上管道含沙量出现顶部小而底部大的现象。另外,管道的断面流速呈现出顶部流速大而底部流速小的现象,且随着含沙量的增大,高流速区扩大且逐渐向管道顶部上移,与大流量工况相比,小流量时高流速区集中且上移明显。垂向流速分布不再呈对称分布而出现管道顶部大、底部小的分布形态,且随着含沙量增大,不对称性更加明显。【结论】多相流混合模型可用于管道输沙流场的模拟计算,模拟结果表明,挟沙水流极大地改变了管道清水流场时呈轴对称分布的流速形态,表现为管道顶部低含沙区流速大,底部高含沙区流速小,�【Objective】This study explored the flow structure of water-sediment two-phase flow and sediment transport characteristics to lay foundation for further study of the variation law of resistance loss with the variations of sediment concentration and velocity in pipeline sediment transmission.【Method】The feasibility of the selected model was verified by the simulation of water flow and turbulent flow in the pipeline using the mixed model of multi-phase flow and the standard k-εturbulence model.The flow field and the resistance of the simulation were compared with the measured and calculated values to determine modelparameters.Combined with the field pipeline pumping test at the Xiaolangdi Dam,multi-phase flow mixing model and standard turbulence model were adopted.Under the pipeline flows of 620m3/h and 950m3/h,sediment concentrations of 3.74%,10.53%,22.64%,37.74% and 45.28% of sediment laden flow were numerically simulated.The flow structure and hydraulic characteristics（velocity,sediment concentration vertical distribution,etc.）were analyzed.【Result】According to the comparison of simulated,measured,and calculated values,roughness of 0.6mm,roughness constant of 0.6,inlet turbulence intensity of 25%were selected to simulate the flow characteristics of silt laden flow in pipeline.The distribution of flow field in pipeline sediment transport at 5sediment concentrations was obtained,including the distribution of water and sediment flow and the distribution of cross section flow velocity.The vertical distribution of velocity and sediment concentration vertical distribution at 5sediment concentrations were summarized.The sediment flow in center section of the pipeline showed that the sand was less in the top and more in the bottom under the flow rates of 620m3/h and 950m3/h.With the increase of sediment concentration,sediment at the bottom of pipe increased.When the sediment concentration increased to 45.28%,the water in pipes was almost dense sand mortar.In vertical distribution,sediment concentration i

关 键 词：数值模拟 管道输沙 参数率定 标准k-ε湍流模型 

分 类 号：TV142[水利工程—水力学及河流动力学]