泄洪闸下游冲刷过程三维数值模拟研究

发布时间：2017-12-27 00:01

本文关键词：泄洪闸下游冲刷过程三维数值模拟研究　出处：《西北农林科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：低水头枢纽具有水头低、流量大、低佛汝德数、消能不充分等特点,造成泄洪闸下游护坦,海漫往往发生不同程度冲刷破坏,甚至导致建筑物损毁,直接影响着水闸运行安全。为此准确预测泄水闸下游局部冲刷坑内流场信息冲刷过程、冲坑形态和最大冲刷深度对于泄水建筑物的安全具有重要意义。本文以巨亭水电站断面模型为研究对象,采用ANSYS FLUENT软件,对其泄流过程及冲刷过程进行了数值模拟,主要结论如下:(1)以RNG k-ε湍流模型封闭N-S方程、有限体积法在计算网格上离散求解、VOF方法追踪自由水面位置,对巨亭水电站模型泄流及冲刷进行了三维数值模拟;通过对比泄流流量、水面线和流速分布等信息,表明数值模拟结果与水工模型试验结果吻合良好,验证了数学模型的正确性;(2)采用C语言编写用户自定义函数,选取起动切应力作为床面泥沙起动判别标准,控制冲刷区域底部边界变化,模拟得到了闸下游局部冲刷过程。与试验数据对比,较大冲刷深度的冲刷坑形态与实测结果符合良好;(3)采用弹簧光顺模型和局部重构模型更新计算区域网格,并使网格重构集中于边界区域,提高了边界区域网格的适应能力及计算结果的准确性;(4)壁面切应力和湍流动能在冲刷过程中基本表现为逐渐减小趋势;在平衡冲刷坑最深点上游,壁面切应力和湍流动能沿程逐渐减小;在其下游,壁面切应力和湍流动能沿程变化不大。
[Abstract]:Low head hub with low head and large discharge, low Froude number, without sufficient energy dissipation characteristics, resulting in Sluice Downstream apron apron, often have different degree of erosion, and even cause damage to buildings, directly affects the safe operation of sluice. Therefore, accurately predicting the flow field information in the local scour pit downstream of the sluice, scouring process, scour pit shape and maximum scour depth is of great significance for the safety of discharge structures. In this paper, Juting hydropower station section model as the research object, using the ANSYS FLUENT software, the discharge process and the scour process was simulated and the main conclusions are as follows: (1) using RNG k- turbulence model closed N-S equation, finite volume method in the calculation of VOF, solving method of discrete grid to track the free surface position. A three-dimensional numerical simulation of Juting hydropower station model of discharge and erosion; by comparing the discharge flow, water level and velocity distribution and other information, show that the numerical results are in good agreement with the results of hydraulic model test, verify the correctness of the mathematical model; (2) using C language user defined functions, select Start shear stress as the bed surface sediment erosion control criterion, change area at the bottom boundary was obtained for downstream local scouring process. Compared with the experimental data, the larger the scour depth of the scour pit pattern and in good agreement with the measured result; (3) using the spring smoothing model and local model updating mesh reconstruction, mesh reconstruction and to focus on the border areas, to improve the accuracy of boundary grid adaptation and calculation results; (4) the wall shear stress and turbulent kinetic energy in the scouring process was gradually reduced; the deepest in the equilibrium scour pit upstream, wall shear stress and turbulent kinetic energy decreases gradually along the way; in the downstream, the wall shear stress and turbulent kinetic energy along the little change.
【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】：2016
【分类号】：TV66

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