泥沙影响流速分布规律的试验研究

Experimental study on effect of sediment on velocity distribution in sediment-laden flow

挟沙水流中泥沙颗粒的存在将影响水流的紊动结构,并进一步影响水流流速分布。采用超声流速仪MicroADV测量挟沙水流的时均流速沿垂线分布,分析了在不同水力条件、不同泥沙条件(包括泥沙浓度及颗粒粒径)下泥沙与水流相互作用对流速沿垂线分布的影响,在此基础上,考虑到现有流速分布公式在实际河道水流流速沿垂线分布中的应用,提出新的指数型流速分布公式形式;并根据实验资料,初步检验了该公式的精度,同时分析了指数型流速公式中系数k和指数m随泥沙浓度s、粒径d以及水力条件的变化规律。结果表明:系数k随泥沙浓度的增加而增大,同时水力条件以及泥沙颗粒粒径同样也影响着k的变化;而指数m随粒径d的增大而减小,随泥沙浓度s的增加而增大。

The turbulent structure and the vertical distribution of the velocity of sediment-laden flow would be effected by the sediment condition including sediment particles' diameters and concentration. In this paper, the MicroADV is used to measure the mean velocity distribution of sediment-laden flow. It analyzes the influence of interaction between the sediment particles and flow on the distribution of the velocity of the flow with the different sediment condition and flow intensity. By verifying the application of the existing distribution formula with the experimental data, a new formula of exponential of the velocity distribution is proposed, at the same time, the variational law of coefficient (k) and index (m) in the new formula with the sediment concentration (s), the diameter of particles (d) and the hydraulic condition is analyzed. It is concluded that the k increases with the increasing sediment concentration, the hydraulic condition and the diameter of particles. However, the m decreases with the increasing diameter of particles, and increases with the increasing sediment concentration.