基于混合模型的管道输沙特性数值模拟研究
发布时间：2019-02-17 15:29
【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,且含沙量越高,不对称性越显著;随着流速增大,水流挟沙能力大大提高,流速分布的不对称性显著降低。
[Abstract]:[objective] to explore the flow field structure and sediment transport characteristics of water and sediment two-phase flow in pipeline, in order to further study the resistance loss with sediment content in pipeline sediment transport process, [methods] the multiphase flow mixing model and the standard k- 蔚 turbulence model are used to simulate the laminar flow and turbulent flow field in clear water to verify the feasibility of the proposed model. The simulated flow field and resistance of the pipeline are compared with the measured and calculated values, and the model parameters are determined, and further combined with the field pipeline sediment pumping test of Xiaolangdi Reservoir, Five kinds of sediment bearing flows with (Q) of 620 and 950m3/h of 3.7410.53 and 22.64% 37.74% and 45.28% respectively are numerically simulated. The flow field structure and velocity, vertical distribution of sediment content and other hydraulic characteristics are analyzed. [results] according to the comprehensive comparison of simulated and measured values and calculated values, the roughness of 0.6mm and the roughness constant of 0.6, are selected. The inlet turbulence intensity of 25% is used to simulate and analyze the flow characteristics of sediment bearing flow in pipeline. The two-phase flow distribution of water and sediment and the velocity distribution of pipeline cross section are obtained under five kinds of sediment content conditions. And the vertical distribution of velocity and sediment content in cross section under five kinds of sediment content are as follows: in the case of pipeline discharge QN620 and Q=950m3/h, the distribution of suspended sediment in the central section of the pipeline is small, small and large. With the increase of the sediment content in the flow, the sediment content at the bottom of the pipeline increases gradually. When the sediment content increases to 45.28, the sediment in the pipeline is almost dense slurry, and the sediment content in the pipeline is small at the top and large at the bottom in the vertical distribution. In addition, the cross section velocity of pipeline presents the phenomenon of high velocity at the top and small velocity at the bottom, and with the increase of sediment content, the high velocity area expands and gradually moves up to the top of the pipeline, which is compared with the large flow condition. When the flow rate is small, the high velocity area is concentrated and the upward movement is obvious. The vertical velocity distribution is no longer symmetrical and the distribution pattern is large at the top and small at the bottom, and the asymmetry becomes more obvious with the increase of sediment concentration. [conclusion] the mixed multiphase flow model can be used to simulate the sediment flow field in pipeline. The simulation results show that the sediment carrying flow greatly changes the axial symmetrical distribution of flow velocity in the clean water flow field of the pipeline, showing that the flow velocity in the low sand bearing area at the top of the pipeline is large, the velocity in the high sediment bearing area at the bottom is small, and the higher the sediment content is, the more significant the asymmetry is. With the increase of flow velocity, the sediment carrying capacity of water increases greatly, and the asymmetry of velocity distribution decreases significantly.
【作者单位】： 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;
【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)
【分类号】：TV134
本文编号：2425313
[Abstract]:[objective] to explore the flow field structure and sediment transport characteristics of water and sediment two-phase flow in pipeline, in order to further study the resistance loss with sediment content in pipeline sediment transport process, [methods] the multiphase flow mixing model and the standard k- 蔚 turbulence model are used to simulate the laminar flow and turbulent flow field in clear water to verify the feasibility of the proposed model. The simulated flow field and resistance of the pipeline are compared with the measured and calculated values, and the model parameters are determined, and further combined with the field pipeline sediment pumping test of Xiaolangdi Reservoir, Five kinds of sediment bearing flows with (Q) of 620 and 950m3/h of 3.7410.53 and 22.64% 37.74% and 45.28% respectively are numerically simulated. The flow field structure and velocity, vertical distribution of sediment content and other hydraulic characteristics are analyzed. [results] according to the comprehensive comparison of simulated and measured values and calculated values, the roughness of 0.6mm and the roughness constant of 0.6, are selected. The inlet turbulence intensity of 25% is used to simulate and analyze the flow characteristics of sediment bearing flow in pipeline. The two-phase flow distribution of water and sediment and the velocity distribution of pipeline cross section are obtained under five kinds of sediment content conditions. And the vertical distribution of velocity and sediment content in cross section under five kinds of sediment content are as follows: in the case of pipeline discharge QN620 and Q=950m3/h, the distribution of suspended sediment in the central section of the pipeline is small, small and large. With the increase of the sediment content in the flow, the sediment content at the bottom of the pipeline increases gradually. When the sediment content increases to 45.28, the sediment in the pipeline is almost dense slurry, and the sediment content in the pipeline is small at the top and large at the bottom in the vertical distribution. In addition, the cross section velocity of pipeline presents the phenomenon of high velocity at the top and small velocity at the bottom, and with the increase of sediment content, the high velocity area expands and gradually moves up to the top of the pipeline, which is compared with the large flow condition. When the flow rate is small, the high velocity area is concentrated and the upward movement is obvious. The vertical velocity distribution is no longer symmetrical and the distribution pattern is large at the top and small at the bottom, and the asymmetry becomes more obvious with the increase of sediment concentration. [conclusion] the mixed multiphase flow model can be used to simulate the sediment flow field in pipeline. The simulation results show that the sediment carrying flow greatly changes the axial symmetrical distribution of flow velocity in the clean water flow field of the pipeline, showing that the flow velocity in the low sand bearing area at the top of the pipeline is large, the velocity in the high sediment bearing area at the bottom is small, and the higher the sediment content is, the more significant the asymmetry is. With the increase of flow velocity, the sediment carrying capacity of water increases greatly, and the asymmetry of velocity distribution decreases significantly.
【作者单位】： 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;
【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)
【分类号】：TV134
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