Study On Water Quality Model Of Incomplete Mixing At Cross Junctions Of Water Distribution System

Water distribution network is the blood vessels of the city, flowing with the city water of life. EPANET Toolkit is currently recognized by the water distribution network modeling of hydraulic and water quality recognized operating conditions simulation of a unified standard. However, the water quality model of the software is based on the premise of the junctions completely mixed, simulating distribution pipe network water quality is a big error.Research on water supply network node mixing law to calculate water supply network water age, the forecast for the chemical substances distribution of water supply network, optimizing the arrangement of water quality monitoring, and to the daily operation of water distribution network maintenance and management, to improve water supply Water quality model accuracy, network optimization scheduling has important theoretical and practical significance, for the water supply network of information and intelligence to provide a solid theoretical and modeling support.Studying on mixing law of nodes, according to the conservation of node flow and node mass, define the mixed node evaluation index L*. L* can quantitatively expressed the degree of pipeline mixed node, more accurately describe the situation of mixed node, and provide the theoretical basis for the study of the mixed node. Study the inlet Reynolds number ratio Re S/W and export Reynolds number ratio Re E/N to the influence of the water supply network nodes mixed.The establishment of water supply network cross node, double T node, H node geometric model, meshing, using Fluent software to CFD numerical simulation; build water supply network single node mixing experiment platform, Nacl as the tracer of water supply network Cross nodes, double T node, and H nodes experimental simulation. Research on single-node incomplete mixing law, and the test results with the foreign experiment and EPANET simulation results were compared and analyzed.By response surface methodology(RSM), central composite experimental design of CFD numerical simulation working conditions, establishment of high significance of cross node to the water supply network, double T node(L = D, 5D, 10D), H node(L = D, 5D, 10D) mixed quadratic model of water quality, reflecting the interaction of the inlet Reynolds number ratio and exports Reynolds number ratio compared theUsing the established water network node incomplete mixing of water quality model with the method of response surface, the program written on traditional EPANET node completely mixed model was optimized. Using EPANET and optimize the EPANET to construct 3?3 water pipe network simulation model. By steady-state solute transport simulation and transient solute transport simulation, comparing the differences between optimizing the EPANET node mixed model and the traditional EPANET node the complete mixing model.Construction of 4?4 water supply network node mixed experiments platform, laboratory network through valve regulation can achieve adjacent inflow and relative flow condition. Compared with CFD numerical simulation, experimental modeling, EPANET simulation, optimization EPANET simulation, the influence of the node mixed. Optimization EPANET node hybrid model that can more accurately describe the node mixing law, improve the accuracy of the calculation model of water quality.The actual water supply network project of SY city has been researched, and the spatial distribution of the chlorine concentration distribution network has been simulated. Based on the pipe network chlorine contour map and the selected node chlorine concentration, we find that the modified EPANET node hybrid model can more accurately describe node mixing law, improve the pipe network water quality model for calculating precision and guide the engineering practice.