基于CFD的深水型水库选择性取水模拟
发布时间：2018-07-15 07:27
【摘要】：选择性取水广泛地应用于实际水库中，理论和试验研究结果表明泄出层厚度均可用一般的数学表达式表示，只是系数C3存在差异，并且通过理论分析和试验数据各自得到泄出层内速度分布表达式。本文利用FLUENT定制浮力传热湍流模型，确定模拟方法，模拟美国陆军工程师团水道试验，模拟与理论误差仅为0.78%。 将模型扩大为实际水库，模拟结果表明：在进行选择性取水时，水体流动可以分为三个区域，抽吸区域、惯性—浮力区域和粘性—对流区域，理论和试验所得到的泄出层厚度及速度无量纲分布公式只适用于惯性—浮力区域，并且在稳定出流的情况下，泄出层厚度为23.80m，建议C3=1.58；通过分析温度分布不同线性化后，，选择性取水流动特性会存在着差异；而孔口大小的变化（在模拟的孔口大小范围内）对选择性取水则没有实质性的影响。 选择性取水的理论研究只局限于水体密度单线型分布，并未对其他密度分布进行研究，通过借鉴Wood分析方法，得出双线性密度分布下的泄出层厚度及系数C3表达式；利用CFD计算软件FLUENT，获到模拟双线性密度下选择性取水的纵向范围、系数C3以及相应速度分布，结果表明泄出层厚度与相应的理论值接近，在分析的距离范围内，误差值在0.3%~13.4%之间，建议系数C3=1.656，速度分布也符合美国陆军工程师团水道试验站的试验结果。 高度固定的取水口一定程度上限制了选择性取水技术的应用，本文提出在取水口安装挡板和增强型挡板，通过上、下档板的旋转达到规避不良水层技术思路。通过建立取水口上侧安装档板和增强型挡板的CFD模型，表明孔口上方挡板能有效减少孔口中心上侧的泄出层厚度和流量，间接增加下侧的取水流量，8m上挡板向下倾斜-30°时，上、下流量分配比达到最大值，为1：4.3，不过4m挡板最为经济适宜，上、下流量分配比为1:3.93；4m增强型上挡板，上、下流量分配比最大值为1：4.78，对于4m增强型下挡板，上、下流量分配比最大值则为3.97:1；无论是挡板还是增强型挡板，倾斜角是这两种技术影响泄出层厚度和流量分配的重要因素。通过数据比较，表明增强型挡板在减小泄出层厚度这方面要优于挡板，而在流量方面，上、下流量分配比得到进一步提高。因此取水口安装挡板和增强型挡板可经济地增强选择性取水的调节范围
[Abstract]:Selective water intake is widely used in practical reservoirs. The theoretical and experimental results show that the thickness of the discharge layer can be expressed by general mathematical expressions, but the coefficient C _ 3 is different. The expression of velocity distribution in the discharge layer is obtained by theoretical analysis and experimental data. In this paper, fluent is used to customize the buoyancy heat transfer turbulence model, and the simulation method is determined to simulate the US Army Corps of Engineers watercourse test. The error between simulation and theory is only 0.78. The simulation results show that the water flow can be divided into three regions, the suction region, the inertial buoyancy region and the viscous convection region. The dimensionless distribution formulas of the thickness and velocity of the discharge layer obtained in theory and experiment are only applicable to the inertial buoyancy region, and the thickness of the discharge layer is 23.80 m under the condition of steady outflow. It is suggested that C _ 3N _ (1.58). After analyzing the linearization of the temperature distribution, The characteristics of selective water intake flow are different, but the change of pore size (in the range of simulated orifice size) has no substantial effect on selective water intake. The theoretical study of selective water intake is limited to the single-line distribution of water density, but not to other density distributions. By using Wood analysis method, the expressions of discharge layer thickness and coefficient C _ 3 under bilinear density distribution are obtained. By using CFD software fluent, the longitudinal range, coefficient C 3 and corresponding velocity distribution of selective water intake under bilinear density are obtained. The results show that the thickness of the discharge layer is close to the corresponding theoretical value, and within the range of analysis distance, The error value is between 0.34% and 13.4%, and the suggested coefficient is C _ 3N _ (1.656), and the velocity distribution is in accordance with the test results of the U. S. Army Corps of Engineers' watercourse test station. The application of selective water intake technology is limited to a certain extent by high fixed intake nozzle. In this paper, the installation of baffles and enhanced baffles at the intake points is proposed, and the technical ideas of avoiding the bad water layer can be reached through the rotation of the upper and lower gear plates. The CFD model of the upper side of the intake port and the enhanced baffle are established. The results show that the upper baffle of the orifice can effectively reduce the thickness and flow rate of the discharge layer on the upper side of the orifice, and indirectly increase the flow rate of the lower side when the upper baffle is inclined downwards to -30 掳. The lower flow distribution ratio reaches the maximum value of 1: 4.3, but the 4m baffle is the most economical and appropriate. The upper, lower flow distribution ratio is 1: 3.93 / 4m enhanced upper baffle. The upper and lower flow distribution ratio is 1: 4.78. For the 4m enhanced lower baffle, the upper, the lower flow distribution ratio is 1: 4.78. The maximum flow distribution ratio is 3.97: 1. The slope angle is an important factor affecting the discharge layer thickness and flow distribution of both the baffle and the enhanced baffle. The comparison of the data shows that the enhanced baffle is better than the baffle in reducing the thickness of the discharge layer, and in the flow rate, the lower flow distribution ratio is further improved. Therefore, the installation of baffles and the enhanced baffles at intake ports can economically enhance the range of adjustment for selective intake of water.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU991.1;TV697.41
本文编号：2123308
[Abstract]:Selective water intake is widely used in practical reservoirs. The theoretical and experimental results show that the thickness of the discharge layer can be expressed by general mathematical expressions, but the coefficient C _ 3 is different. The expression of velocity distribution in the discharge layer is obtained by theoretical analysis and experimental data. In this paper, fluent is used to customize the buoyancy heat transfer turbulence model, and the simulation method is determined to simulate the US Army Corps of Engineers watercourse test. The error between simulation and theory is only 0.78. The simulation results show that the water flow can be divided into three regions, the suction region, the inertial buoyancy region and the viscous convection region. The dimensionless distribution formulas of the thickness and velocity of the discharge layer obtained in theory and experiment are only applicable to the inertial buoyancy region, and the thickness of the discharge layer is 23.80 m under the condition of steady outflow. It is suggested that C _ 3N _ (1.58). After analyzing the linearization of the temperature distribution, The characteristics of selective water intake flow are different, but the change of pore size (in the range of simulated orifice size) has no substantial effect on selective water intake. The theoretical study of selective water intake is limited to the single-line distribution of water density, but not to other density distributions. By using Wood analysis method, the expressions of discharge layer thickness and coefficient C _ 3 under bilinear density distribution are obtained. By using CFD software fluent, the longitudinal range, coefficient C 3 and corresponding velocity distribution of selective water intake under bilinear density are obtained. The results show that the thickness of the discharge layer is close to the corresponding theoretical value, and within the range of analysis distance, The error value is between 0.34% and 13.4%, and the suggested coefficient is C _ 3N _ (1.656), and the velocity distribution is in accordance with the test results of the U. S. Army Corps of Engineers' watercourse test station. The application of selective water intake technology is limited to a certain extent by high fixed intake nozzle. In this paper, the installation of baffles and enhanced baffles at the intake points is proposed, and the technical ideas of avoiding the bad water layer can be reached through the rotation of the upper and lower gear plates. The CFD model of the upper side of the intake port and the enhanced baffle are established. The results show that the upper baffle of the orifice can effectively reduce the thickness and flow rate of the discharge layer on the upper side of the orifice, and indirectly increase the flow rate of the lower side when the upper baffle is inclined downwards to -30 掳. The lower flow distribution ratio reaches the maximum value of 1: 4.3, but the 4m baffle is the most economical and appropriate. The upper, lower flow distribution ratio is 1: 3.93 / 4m enhanced upper baffle. The upper and lower flow distribution ratio is 1: 4.78. For the 4m enhanced lower baffle, the upper, the lower flow distribution ratio is 1: 4.78. The maximum flow distribution ratio is 3.97: 1. The slope angle is an important factor affecting the discharge layer thickness and flow distribution of both the baffle and the enhanced baffle. The comparison of the data shows that the enhanced baffle is better than the baffle in reducing the thickness of the discharge layer, and in the flow rate, the lower flow distribution ratio is further improved. Therefore, the installation of baffles and the enhanced baffles at intake ports can economically enhance the range of adjustment for selective intake of water.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU991.1;TV697.41
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