弯道水流结构及其床面演变试验研究

发布时间：2018-05-29 21:48

本文选题：弯道水流 + 环流　；参考：《天津大学》2014年硕士论文

【摘要】：水资源与人类生活各个领域紧密相关,近年来,在许多水力学领域取得了丰硕成果,但我们对弯道水流的三维水流结构、紊动特性、河流床面形态及演变的认识仍有待进一步深入,这使得在预测河床演变、应对突发情况等方面面临着一定的困难。由此可见,针对天然弯道中水流的水动力特性以及河床地貌形态演变的研究十分必要。由于实测资料的获取较为困难且存在费用昂贵、精度较差的问题,我们将在室内明渠弯道水槽中开展研究。本实验设计了一个由一个180o弯段和两个直段组合而成的常曲率弯道水槽模型,运用声学多普勒测速仪对模型中水流进行精细测量,并获取到每个测点三个不同方向的瞬时速度,以此为基础展开分析。本文分析了水流流向平均流速及其速度等值线图、水动力轴线,沿垂线分布的三个方向的流速及弯道环流,并得到了在单弯道中水流结构特点,为天然河流连续弯道的研究打下了基础。弯道水流运动以及泥沙输移将引起河流床面形态的改变,这对河流演变具有重要影响。根据水流阻力规律,对床面形态进行预测是河流动力学中研究的一个重要研究方面。河流在流动过程中存在水流阻力损失,而水流阻力损失则随着来水来沙条件和床面形态的改变而改变。水流阻力规律既决定于床面形态,同时也能反映床面形态特征。基于河流阻力规律这一理念,本文结合水槽试验研究成果,根据水流阻力规律表达形式,对不同床面形态进行了区分,给出两个决定床面形态的无量纲参数,绘制了不同床面形态的划分图,论述了床面形态变化与床面形态参数之间的关系,得到了床面高、低能态的分界线方程以及不同床面形态间的分界线方程,确定了不同阶段的床面形态判别标准表达范围。
[Abstract]:Water resources are closely related to every field of human life. In recent years, great achievements have been made in many fields of hydraulics. The understanding of the shape and evolution of river bed surface needs to be further deepened, which makes it difficult to predict the river bed evolution and to deal with unexpected situations. Therefore, it is necessary to study the hydrodynamic characteristics of water flow in natural bends and the evolution of river bed geomorphology. Due to the difficulty of obtaining the measured data and the problems of high cost and poor precision, we will carry out the research in the indoor open channel bend flume. In this experiment, a constant curvature bend flume model composed of a 180 o bend and two straight sections is designed. The acoustic Doppler velocimeter is used to measure the water flow in the model, and the instantaneous velocities in three different directions of each measuring point are obtained. On this basis, the analysis is carried out. In this paper, the average flow velocity and its velocity isoline map, hydrodynamic axis, flow velocity and curved circulation in three directions along the vertical line are analyzed, and the characteristics of the flow structure in a single bend are obtained. It lays a foundation for the study of continuous bend of natural rivers. The flow movement and sediment transport in curved channel will cause the change of river bed shape, which has an important influence on river evolution. According to the law of flow resistance, prediction of bed shape is an important research aspect in river dynamics. In the course of flow, the flow resistance loss of the river changes with the change of the condition of incoming water and sediment and the shape of bed surface. The flow resistance law is not only determined by the bed shape, but also can reflect the bed surface characteristics. Based on the concept of river resistance law, combined with the research results of flume test, according to the expression form of flow resistance law, different bed surface forms are distinguished, and two dimensionless parameters determining bed surface shape are given. The partition diagram of different bed surface morphology is drawn, and the relation between bed shape change and bed surface shape parameter is discussed. The boundary equation of bed surface high and low energy state and the boundary line equation between different bed surface morphology are obtained. The standard expression range of bed surface morphology at different stages was determined.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV147

【参考文献】