管道高含沙水流卵石运动机理及其互馈效应

Big pebbles are often sucked into the pipe for reservoir desilting of engineering practice, thus making pipe blockage events happen. Under the driving force of high sediment concentration flow, pebbles move and then exert feedback effect on the flow field of high sediment concentration flow, which will lead to the increase in the energy consumption of transport system and the decrease in the transport efficiency. The mechanisms of pebble movement and mutual feedback between pebbles and high sediment concentration flow in the pipe are the key technical problems for effective pipe transport of sediment. With the limited testing technologies, the current related experimental researches focus on the mutual feedback mechanism between pebbles and water in the pipe. However, there is a big difference between the physical characteristic of high sediment concentration flow and that of water. This research will utilize the physical experiments to confirm parameters of CFD-DEM numerical simulations, and then use the CFD-DEM numerical simulations to obtain the whole information about pebble movement and flow field of high sediment concentration flow. When the pebble size, high sediment concentration flow velocity, sediment concentration and slope angle of pipe are different, the pebble movement mechanism and how pipe transport efficiency varies will be clarified. The mechanism of feedback effect of pebble movement on the flow field of high sediment concentration flow will be studied. The energy consumption mechanism of pipe transport will be revealed. Findings in this research could not only provide technical support and theoretical basis for the engineering design of sediment transport in the pipe, but also play a significant role in promoting the subject of engineering sediment.

水库清淤等工程实践中经常出现大块卵石进入管道，造成淤堵事件。卵石在高含沙水流驱动下输移时会对高含沙水流结构产生反馈影响，增加系统能耗，降低输送效率。管道高含沙水流卵石运动机理及其互馈效应是管道排沙中的关键技术难题。受限于测试技术，目前相关试验研究大多采用清水为管道载流，而高含沙水流物理特性与清水有很大区别。本项目拟深入结合物理试验和流-固耦合CFD-DEM数值模拟技术，通过物理试验率定数值模拟参数，通过数值模拟获取高含沙水流与卵石运动全过程信息，探明不同卵石粒径、高含沙水流流速、含沙量、管道逆坡倾角等条件下卵石运动机理及管道输送效率变化规律，研究卵石运动对高含沙水流结构的反馈影响机理，揭示管道高含沙水流卵石输送系统能耗机制。研究成果不仅可为管道输沙工程设计提供技术支持和理论依据，而且对工程泥沙学科的发展具有重要的推动作用。

水库清淤等工程实践中经常出现大块卵石粗颗粒进入管道，造成管道淤堵。管流粗颗粒运动机理及其互馈效应是管道排沙中的关键技术难题。本项目采用现状分析、数值模拟、模型试验和理论推导等研究方法，结合颗粒介质力学、流体力学和泥沙动力学等基本理论，建立了描述排沙管道粗颗粒运动堆积过程的流固耦合数值模拟方法与物理模型试验装置，深入研究了排沙管道粗颗粒输送机制及力学过程。主要研究成果如下：.（1）阐明了不同粗颗粒粒径和粗颗粒输沙率、管流流速、管流挟沙、管道倾斜角度条件下管道固液两相流输移机制，提出了粗颗粒运动状态界定参数以及粗颗粒粒径、输沙率、管流流速常见工况下粗颗粒输送机制三维分布特征图。（2）明晰了不同管道输送机制条件下管道压强特性分布规律，构建了粗颗粒粒径和粗颗粒输沙率、管流流速、管流挟沙、管道倾斜角度与管道时均压强沿程损失、脉动压强振幅概率分布、功率谱分布之间的内在联系。（3）揭示了各影响因素变化对水流结构的反馈作用，阐明了管道流体粗颗粒输送系统能耗机制。研究成果为管道固液两相流高效输送与稳定设计提供了理论参考和技术支撑，为河流湖泊疏浚工程、矿石管道输运等其他工程领域固液两相管道流输送机理研究提供了科学依据。.本项目发表学术论文14篇，其中SCI/EI检索6篇，申请及授权国家发明和实用新型专利5项；培养研究生5名、青年科技人才3名，参加国内外学术会议12人次，形成了一支从事管道水力输送理论的高水平研究团队。