【作者】 郝晶晶；

【导师】 马孝义；

【作者基本信息】 西北农林科技大学 ， 水力学及河流动力学， 2008， 硕士

【摘要】 在农业节水灌溉各项技术的推广应用中,灌区量水是一项基础的、关键性的技术。随着节水农业的发展和水价制度的改革,研究结构简单、精度高的渠道流量测量装置具有重要的意义。本文选用五元二次正交旋转组合设计方法,利用GAMBIT建立模型,划分网格,基于标准k -ε二阶紊流模型,采用VOF方法和壁面函数法分别处理自由液面、不规则边界和固壁边界,对抛物线量水槽三维水流运动进行了数值模拟研究,主要得到以下结论:(1)对小型U形渠道抛物线量水槽建立模型,进行水位流量的模拟计算,得到不同工况下量水槽的自由水面线、流速分布等表明其过流特性的水力参数,并将其与试验资料进行对比,结果表明,自由水面线的计算与实测值符合较好,流速分布规律揭示的水流特性与实际状况相符,所选模型能够准确模拟量水槽的三维水流特性,该数值数值模拟方法具有可靠性。(2)在模型验证取得良好效果的基础上,为了在较大范围内研究抛物线量水槽的过流特性、自由出流时流量的变化规律,探讨渠道断面尺寸大小(不同的渠底半径r、外倾角α和渠道比降i,糙率n)和抛物线收缩比ε对量水槽流量计算的影响,本文采用五元二次正交旋转组合设计方法,建立数值模拟试验方案,对不同参数的渠槽进行了数值模拟计算。(3)采用DPS数据统计分析软件结合试验统计分析原理,对数值试验的模拟结果进行回归分析,得出以流量为因变量的五元二次回归方程。(4)利用简化模型,对已有的量水槽测流结果及较大半径U形渠道抛物线形量水槽进行了验证,初步表明,已有流量公式对较大半径U形渠道抛物线形量水槽具有较高的合理性。(5)根据建立的回归模型,探讨了不同渠槽结构参数对水位流量关系的影响。经过对流量的各个参数进行了单因子及两因子交互作用分析,结果表明,渠道半径及相对水深对流量影响较为显著,抛物线收缩比ε与渠道比降i对能否形成统一的水位流量关系有较大的影响,而渠道的外倾角α及糙率n对水位流量关系影响较小,而糙率的平方项对流量的影响较大。更多还原

【Abstract】 Measuring water of irrigation district is basic in the popularization and application process of agricultural water-saving irrigation technology. With water saving agriculture development and pricing mechanism reform, it is important to study simple structure and high precision flow measurement devices. quadratic-orthogonal-rotation-combination design,k -εturbulent model combining with VOF method, porosity method and wall function was used to simulate and research the flow of parabola-shape flow measurement flume. The main research results as follows:(1) The mathematical model of unsteady three-dimensional in parabola-shape flow measurement flume is created in this paper. The computed results and the data obtained by the authors in test were compared, and they agree well. This result shows that the model can simulate the flow and free surface around parabola-shape flow measurement flume.(2) Quadratic-orthogonal-rotation-combination design is used to research the effect on discharge created by the cross-section size of U-shape-channel and parabola-shape flow measurement flume. According these test methods, this paper has simulated the discharge in the parabola-shape flow measurement flume.(3) Based on DPS Data-Processing System and the numerical simulations results, the author establish Simulation discharge regression model, which describe the relationship between cross-section sizes and discharge.(4) The relative error of Simulation and calculation solution of discharge in detail is analyzed in different Cross-section sizes of parabola-shape flow measurement flume. The result shows that the simulation vale is reliable. And simulation discharge regression model can use to calculate the discharge.(5) According to the simulation discharge regression model, the effect of single and two factors on different water and discharge relationship are analyzed. The result shows that the interaction effect caused by radius and relative depth is clearer than radius and extraversion angle; the roughness of channel has less effect on discharge. However, contraction ratio and slope of channel have more effect on water stage and discharge.更多还原