【作者】 禹明忠；

【导师】 王兴奎；

【作者基本信息】 清华大学 ， 水力学及河流动力学， 2002， 博士

【摘要】 本文研制开发了表面流场实时测量系统和颗粒三维运动测量系统，并采用颗粒三维运动测量系统对明槽水流中粗颗粒的运动进行了系统的试验研究。在最新测速方法和颗粒运动特性的研究方面取得了新进展，研究结果对促进河流动力学学科的发展及各种工程的应用具有重要的理论意义和生产实用价值。●采用多CCD摄像机和多台计算机、视频信号同步、局域网同步等技术，首次实现了大范围流场的实时测量，在20秒钟之内测量1000 m2以上的流速场。●实现了实时图像序列的逐帧粒子匹配方法以保证测速精度。提出了循环采样和顺序采样交互运行的模式，解决了各种复杂流动条件下连续实时测量的关键技术难题。上述成果具有创新性，已得到了广泛应用，并申请了一项发明专利。●建立了颗粒三维运动测量系统，提出了“空间多层正交网格”的标定方法，用“多次迭代逼近法”进行颗粒空间坐标的计算。●对不同的粒径和不同的水流条件，颗粒纵向平均速度都符合对数分布规律，垂向和横向的平均速度属于随机波动的范围。颗粒垂向浓度分布符合扩散方程，修正系数β>1。●颗粒紊动强度随粒径的增大而减小，随Fr的增大而增大，随Re的增大而减小。颗粒速度的紊动强度为速度的空间变化和时间变化共同作用的结果。●颗粒脉动速度的概率密度分布随流区有所差异；在空间尺度影响较小的范围接近正态分布；各种粒径的颗粒脉动速度具有相似的特性。●在推移区内，颗粒的纵向速度沿垂线接近对数分布，平均运动速度为8． 2u*；颗粒的浓度沿垂线基本为线性分布，底部比上部大3倍左右，说明Einstein取的悬移质参考浓度Ca会有所偏大。●颗粒剪切应力的数值约为水流紊动剪切应力的5％。颗粒因阻力作用在就地损耗的能量e在底部流区随高度的增加而线性减小。上述有关颗粒三维运动规律的研究虽为探索性的成果，但在科技文献中还没有见到系统的报道，因而具有新颖性。更多还原

【Abstract】 Real-time surface velocity field measurement system and three-dimensional particle velocity measurement system are developed. Systematic experimental research on the movement of coarse sediment particles in open-channel flows was carried out using developed system. Advances have been achieved in the development of velocity measurement approach and the research on the characteristics of particle movement. The results have great value in both theoretic research and practical application of River Dynamics.With multi-CCD and multi-computer system, video and sampling synchronization technique in LAN adopted, real-time measurement of large-scale flow field was achieved. Velocity distribution of the flow field with an area larger than 1000 m2 can be measured in 20 seconds. Successive-frame particle match approach was implemented to ensure high measurement precision. The mixed usage of the successive-sampling and the loop-back-sampling approaches ensures high precision when measuring complicated flows consecutively in real time. A patent has been applied for based on these widely used innovations.A 3D particle velocity measurement system was built upon calibration method of multi-layer regular grid and particle space coordinates determination method of iterative approaching developed in this paper.The distribution of stream-wise particle velocity follows the log-law under various flow conditions and for different particle diameters, and the fluctuation of the other two velocity components is random. The vertical distribution of particle concentration fits Rouse’s equation well with > 1.The turbulence intensity of particle velocity decreases when particle size or Re increases and increases with the increase of Fr. The turbulence intensity is the result of space variation and temporal variation of particle velocity.The probability density distribution of the particle velocity fluctuation differs in different flow regions, and is approximately normally distributed where the space restrictions are small. Velocity fluctuation of particles with different sizes is similar.In the bed load layer, the stream-wise particle velocity profile follows the log-law, and the average is 8.2u*. The vertical distribution of particle concentration is nearlylinear, and the concentration at the bottom is 3 times larger than that at the top, which indicates that Ca , the reference concentration of suspended particles in Einstein’s equation, is larger.The shear stress of particles is about 5% of the turbulent shear stress of the water. The local energy dissipation of particles caused by the resistance decreases linearly with the increase of the height in the bottom flow region.Though preliminary, these results on three-dimensional movement of particles are novel, and there is no similar systematic research published.更多还原