高低含沙水流流速分布的统一规律

Unified laws of velocity distribution for sediment laden flow with high and low concentration

作为自然界中普遍存在的一种典型的固液两相流,挟沙水流流速分布具有与清水不同的变化规律。本文明确挟沙紊流(无流核)为研究对象,通过天然沙挟沙水流流速试验,首先分析紊动状态下高、低含沙水流流速分布特点;在此基础上,通过引入同时反映含沙量和颗粒级配影响的相对黏度指标,分析高、低含沙紊流的卡门常数κ统一规律及其表达式,由此将高、低含沙水流流速分布统一于卡尔曼-勃兰德尔对数流速分布公式上,并应用室内粉煤灰等试验资料分别验证了卡门常数κ及卡尔曼-勃兰德尔对数流速分布公式的合理性和可靠性;本项研究成果对进一步揭示高、低含沙水流的水流结构与输沙机理以及对河道整治规划设计具有重要的现实意义。

As a typical solid and liquid phase flow existing universally in the nature, it is well-known that the velocity distribution laws of sedimetn laden flow is different from those of clear water flow. By means of velocity measurements for sediment laden flow in the natural sand tests, the characteristics of turbulent flow with high and low concentration has been analyzed comprehensively in this paper. Furthermore, according to basic logarithm formula of velocity distribution, unified formula of Karman constant κ for the flow with high and low concentration has been reasonably expressed by using relative viscosity index μ, to be related to concentration and grain diameter distribution. Finally, by comparing and verifying for two kinds of velocity formulas, the unified laws of logarithm velocity distribution with both Karman-Prandtle velocity and Karman constant κ has been analyzed and verified by using measured velocity data in the coal powder tests. The achieved results above are significant for revealing water flowing structure and sediment transporting mechanism, enriching river mechanics and guiding fiver harnessing engineering.