城市排水管网瞬变混合流数值模拟与机理实验研究

Transient mixed flow is very common in drainage systems, and to deeply research its mechanism and accurate simulation technology is of great significance for urban drainage models and rainstorm flood simulations. The flow in the drainage system is often affected by both man-holes and pipes, the existing theory mostly assumes the man-hole as a point, and the hydraulic change is space is not considered, which is unreasonable when simulating the transient mixed flow (especially in the pressure flow zone), and needs to be improved. The mechanism and numerical simulation of the transient mixed flow under the joint influence of man-holes and pipes will be researched based on physical experiment and mathematical model. Through the physical experiment, the hydraulic characteristics of the transient mixed flow through man-holes under different conditions will be revealed quantitatively, and a drainage model capable of simulating complex flow regimes such as free-surface flow, pressure flow and transient mixed flow will be proposed based on the Godunov finite volume method. By using the proposed model as a tool and carrier and applying the physical experimental data, a dynamic hydraulic calculation method of man-holes suitable for transient mixed flows will be proposed. Thus, hydraulic characteristics in the man-holes can be calculated more accurately, and the simulation accuracy of the drainage network model to the transient mixed flow and the applicability of the model can be improved to provide better model technical support for drainage system planning, flood control and sponge city construction.

瞬变混合流在排水管网中是普遍存在的，研究其机理和精确模拟技术对城市排水模型和雨洪模拟精度的提升意义重大。排水管网中的水流受雨水井和管道共同作用，但现有理论多将雨水井假定为一个点，严格来说这在模拟瞬变混合流（压力流区域）时并不合理，不能考虑井内水力要素的空间变化，亟待改进和完善。本项目以物模实验和数学模型为基本手段，研究雨水井与管道共同作用下，瞬变混合流的机理和数值模拟问题。通过物模实验，定量揭示不同条件下瞬变混合流通过雨水井时的水力特性，基于Godunov型有限体积法构建能够模拟明渠流、压力流和瞬变混合流等复杂流态的排水模型，并以此为工具和载体，结合实验数据，研究并提出适用于瞬变混合流的雨水井水力计算新方法，准确地计算雨水井内的水力变化，从而提升排水管网模型对瞬变混合流的模拟精度和模型整体适用性，为排水规划、防洪排涝和海绵城市建设提供更好的模型技术支持。

城市雨洪模型是暴雨内涝预警预报、洪水应急管理以及城市土地利用和排水规划等方面的重要工具。精细化的城市雨洪模型离不开对排水管网水流的准确模拟，其很大程度上决定了雨洪模拟的精度，提升对瞬变混合流的模拟精度和排水模型整体适用性具有重要意义。本研究在开展国内外排水管网模型理论方法和物理模型实验调研的基础上，基于有限体积法思想，采用HLL格式，开发了管网与河网一体化的一维管网模型，并采用不同算例对模型进行了测试。为了研究排水管网瞬变流特征，特别是雨水井内水位分布特点，开展了排水管网瞬变流实验，总结了相应规律，为排水数值模型修正和精度提升奠定了基础。本项目研究进展顺利，已发表本基金资助标注专著1部，论文9篇，其中SCI收录2篇，中文核心5篇；受项目资助申请了2项国家发明专利；参加国内外会议4人次，作会议报告2人次。本项目已经完成的研究成果达到了预期的研究目标。通过本项目的研究，初步形成了较完整的一维排水模型，可为防灾减灾、城市排水规划等提供理论依据和技术支撑。