排沙漏斗水力特性及悬移质排沙机理研究

A vortex settling basin is a new type of desilting facilities which use vertical spiral flow to exclude sediment particles from the diverted water. The device is an economical, efficient, and water-conserving choice for sediment exclusion, and has attracted a great deal of attention and research. But the mechanism of vortex settling basin for exclusion of suspended sediment has not yet been fully understood. In this study, the turbulent flow structure and the effect of Coriolis force on the air column in vortex settling basin will be explored by means of model test and numerical simulation. Based on numerical simulation of the flow in vortex settling basin, suspended sediment movement will be calculated with particle trajectory model and will be tested with prototype observation data, and a three-dimensional numerical model for flow and suspended sediment transport in this device will be established. The mechanism of excluding suspended sediment in vortex settling basin will be revealed by analyzing the hydraulic characteristics and suspended sediment motion. It will provide a theoretical basis to improve the performance of vortex settling basin for exclusion of fine suspended sediment.

排沙漏斗是一种利用立轴螺旋流实现水沙分离的新型排沙设施，以其占地面积小、冲沙耗水率低、截沙率高等优点引起大量关注和研究，但其悬移质排沙机理仍未被充分了解。本研究通过模型试验和数值模拟手段，探讨排沙漏斗流场结构，分析科氏力对空气柱的影响。在排沙漏斗水流模拟的基础上采用颗粒轨道模型计算悬移质颗粒运动，结合原型观测资料建立排沙漏斗三维悬移质泥沙数学模型，基于排沙漏斗水力特性和悬移质运动规律揭示排沙漏斗悬移质排沙机理，为提高排沙漏斗对细颗粒泥沙的排沙性能提供理论基础。

经过大量的国内外工程实践已证实排沙漏斗是一种高效的灌区和水电站引水排沙设施，但由于排沙漏斗为复杂的三维三相流动，排沙漏斗的水流泥沙运动规律和排沙机理目前仍不十分清楚。本项目对排沙漏斗水流流场和悬移质含沙量分布进行了测试，并进行了排沙漏斗水气两相流数值模拟和排沙漏斗泥沙数值模拟。研究得到：（1）在排沙漏斗悬板下和悬板下游区域存在强烈的向外的径向流速；（2）建立了排沙漏斗悬移质泥沙数学模型；（3）在漏斗室外侧区域含沙量分布整体上较均匀，在漏斗室内侧区域的近底部存在一个明显的高浓度带；（4）提出二次流是排沙漏斗能够顺畅高效排沙的关键。上述研究结果推进了对排沙漏斗排沙机理的认识，有助于更好地使用数值模拟手段来辅助设计排沙漏斗工程，也为在具有复杂形状自由水面的水利工程中进行泥沙数值模拟提供了有益借鉴。