| In recent years, a lot of manpower and material resources has been invested to control the water pollution in Dianchi. So far, during the "Ninth Five Year", "Tenth Five Year" and "Eleventh Five Year", the implementation of the completion of a series of key pollution control projects have built up the Dianchi Lake watershed control ranging from the source pollution control system to the end of the drain grating system. In order to prevent the deposition of pollutants in the Dianchi Lake sewage interception trunk, carrying out investigation, studying on the status of the main channel of the deposition and put forward suggestions of optimization by simulation are very important.In order to prevent channel siltation, this paper studies on the siltation status quo of the eastern section of the canal storm water drains. The storm water drains model was constructed for solid-liquid two-phase flow simulations, using three-dimensional design Software Solidworks and simulation software Fluent, to investigate and analysis the opening degree of the sand gate which meets the requirements of the project and the spacing of gates for ensuring no silt when sand washing.The following main conclusions are drawn through the analysis of the current situation of the deposition:(1)There are different degrees of deposition in the study area drains of the trunk. The pollutant deposition amount is increasing with the channel operation time going on.(2)In the case of different sources of sewage, sediment deposition in the channel has a significant difference. Distribution of different rainwater drainage amount of sediments is as follows: Dounan village sewage sampling point > slaughterhouse wastewater sampling point > agricultural irrigation district sewage sampling point > access Chenggong County sewage sampling point.(3)The slope of the rainwater channel affects the flow rate in the channel and then influences the sediment deposition and the hydraulic erosion. In this research area, from the sampling point of the irrigation waste water from the vegetable greenhouse, the pollutant deposition rate increases quickly.(4)The effect of climate on sediment deposition is mainly influenced by rainfall. The limit of the dry season and rainy season in Kunming is obvious; the amount of sediment in the dry season was significantly higher than that in the rainy season.The following conclusions are drawn from the analysis of the characteristics of the sediments:(1)Relationship between the sampling points of the organic matter content is as follow: slaughterhouse waste sampling point > Dounan village fairs sewage of sampling point > Dounan village sewage sampling point > vegetable greenhouse irrigation wastewater sampling point > Chenggong County sewage sampling point.(2)The relationship between the sampling points of the total nitrogen content is as follow: vegetable greenhouse irrigation wastewater sampling point > Dounan village fairs sewage of sampling point > slaughterhouse waste sampling point > Dounan village fairs sewage of sampling point > Chenggong County sewage sampling point.(3)The relationship between the sampling points of the total phosphorus content is as follow: vegetable greenhouse irrigation wastewater sampling point > Dounan village fairs sewage of sampling point > Dounan village fairs sewage of sampling point > slaughterhouse waste sampling point > Chenggong County sewage sampling point.(4)For the vegetable greenhouse irrigation sewage sampling points, the total nitrogen and phosphorus growth of the rainy season was significantly higher than the dry season. The impact of rain on the sediment particle concentration is greater.The Fluent drains based on the simulation results analysis the main conclusions are as following:(1)The current situation of storm water drain gate is as follow: The distance between the beginning of the storm water drains and the first gate is 615 m. It is found from the simulation that the initial gate should be located at a distance of 440 m from the beginning of the storm water drains. The gate setting position can't to prevent sediment timely; in six cases, the spacing of the first gate and the second gate are closer than the status quo. The result shows that the status of the gate spacing does not prevent sediment deposition effectively.(2)Through a different gate opening degree of simulation, the smaller the gate opening degree is, the stronger agitation of the flow, the more the flow of the channel bottom violent scour range and the vortex formation is, the more intense the stir sediments. But the water capacity is low. Since the storm drains is responsible for the collection of sewage of the Dianchi Lake, storm water drains water capacity directly affects the canal water collecting ability. The gate opens 1.5m to be more in line with the project application.(3)Through the simulation of different distances between the gate, it is found that the smaller the gate open degree is, the larger the space of gates is, the fewer gates the channel needs. By comprehensive consideration, the gate opening 1.5m is more in line with the engineering application and the optimal gate spacing is 1100 m when there is no deposition... |
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