| With the deepening of urbanization and industrialization in our country,the scale of urban water supply is also increasing day by day.For some cities lacking surface rivers,reservoirs and lakes have become the main water supply sources.As major water sources,they are greatly influenced by natural and human factors,and the self-purification capacity of reservoirs and lakes is worse than that of ordinary rivers.Therefore,it is necessary to take measures to purify water quality in water sources.The object of this paper is the water intake project of a reservoir.It is mainly based on CFD commercial software Fluent to numerically simulate the distribution of liquid flow field and substrate in the middle and lower layers of the reservoir when the water pump takes water from the reservoir,and discusses the optimization measures of flow field in the middle and lower layers of the reservoir,so as to explore the optimal implementation scheme.First of all,without any optimization measures,the flow of water and the movement of underwater substrates?velocity analysis,pressure analysis,substrate concentration analysis?are simulated and analyzed when the water pump in the reservoir takes water.In addition,the VOF and k-?turbulence solid-liquid two-phase flow models are adopted in the flow field simulation within the research scope.In order to achieve higher accuracy,before the numerical simulation,the established water intake model is verified for grid number independence and time step independence,and the optimal grid size is 540,000 and the optimal time step is 5×10-5s.Secondly,a thin-walled cofferdam with a height of h and a diameter of d will be added to the bottom of the reservoir.After changing the height h and diameter d of the cofferdam,the numerical simulation of the flow field and the distribution of substrates when the water pump absorbs water is carried out,and the optimal cofferdam size that can prevent the suction of substrates is obtained.Finally,because the reservoir is the only source of water intake near Yingshan County and has been approved by EIA and the local environmental protection department,CaO is added to the study area based on H=0.35m and D=0.5m cofferdam,and the scope of CaO is controlled in a circle with a diameter of about 3.5m.At the same time,a nozzle is installed on the suction pipe of the pump,which can be used to add CaO to the water in time and on demand when the pump is working.Then the matrix motion distribution in the flow field of the middle and lower layers of the reservoir is simulated again.Through classification and comparative analysis of the above 18 simulation results,the specific optimization scheme is as follows:?1?Cofferdam with diameter D=0.5m and height H=0.4m is adopted.?2?when the water level continues to drop in summer and the water quality deteriorates seriously,a cofferdam with diameter D=0.5m and height H?0.35m is adopted for the study area.The research on the specific optimization scheme of this project can provide reference for the optimization design of similar water intake projects. |
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