水源地取水泵站预沉曝气池及前池流态改善CFD研究
发布时间：2019-06-20 06:09
【摘要】：水源地取水泵站包括预沉池、曝气池、前池3个主要部分,取水泵站内流速小,水位变幅大,内部流态紊乱。当取水泵站内无水力优化措施时,预沉池内水流流态紊乱,曝气池及前池内存在回流区、死水区以及漩涡,取水泵站内的不良流态会导致曝气池及前池局部泥沙沉淀和入泵水流流速分布不均匀。本文通过CFD技术,对水源地取水泵站工程整流措施展开研究,重点研究了预沉池前穿孔花墙配水均匀性,预沉曝气池与前池联合运行时整体水力优化措施,以及多泵运行模式下前池内流动特性和水泵吸水均匀性的差异。研究成果对进一步改善取水泵站内水流流态,防止泥沙淤积,提高水泵运行的安全性、高效性有一定的指导意义,为多泵运行条件下开泵方式的选择提供参考。(1)运用商用软件ANSYS 14.5,紊流模型选取标准k-ε紊流模型。通过网格无关性分析,确定取水泵站整体网格总数为175.6万。(2)预沉池穿孔花墙水力优化研究。不同水位条件下,不同形式(矩形、圆形、菱形)的穿孔花墙配水均匀性存在较大差异;采用菱形穿孔花墙进行配水,水流在预沉池内流速分布更加均匀,流态相对平顺,有利于泥沙等固体颗粒悬浮物的沉降。(3)取水泵站内流动特性研究。对于斜坡闸孔入流取水泵站、斜坡扩散自由入流取水泵站,在无措施条件下,其内部流态较为紊乱,在曝气池廊道转角处、斜坡段均存在明显脱流、漩涡以及回流区,且水流进入前池后存在严重偏流问题。斜坡闸孔入流取水泵站在斜坡段存在大面积回旋区,水流以射流形式进入前池很难扩散均匀;斜坡扩散自由入流取水泵站则在斜坡段和前池内易形成大面积回流区。(4)取水泵站曝气池流态改善研究。曝气池廊道转角处倒圆角、廊道转角内设U形导流墙和1/4弧形导流墙,有效地消除了廊道内存在的脱流、死水区;在斜坡段设双U形导流墙和等分双隔墩有效地改善了斜坡段明显的偏流问题,削弱了斜坡段回流漩涡的发生,使得水流相对平顺地进入前池。(5)斜坡闸孔入流取水泵站前池流态改善研究。前池无整流措施时,水流通过闸孔射流形式直接撞击后壁,在两侧形成大面积回流,且各泵机组吸水均匀性差异较大,各泵喇叭管入口断面流速均匀度呈现倒V字分布,中间3#机组吸水均匀性较高,两侧机组吸水均匀性较差。通过在前池内两闸孔中线处设置八字形导流墩、泵机组间设置隔墩、改变前池两侧直角翼墙等组合措施,明显改善了前池内流态及流速分布,特别是底层水流扩散均匀,基本无明显漩涡存在,且面层大面积回旋区得到较好地控制,各泵机组吸水均匀性均得到提高,各泵吸水均匀性差异明显减小。(6)斜坡扩散自由入流取水泵站前池流态改善研究。前池无整流措施时,水流通过扩散段进入前池,在前池的两侧形成回流区,同时在靠近前池后壁处有局部漩涡发生;此时,各泵机组吸水均匀性呈现两侧机组高,中间机组低。通过在泵机组间设置隔墩、在前池内设置八字形导流墩、设置45°倾斜挡板等组合措施,明显改善了前池内流态及流速分布,提高了各泵机组吸水均匀性均。其中,隔墩高度的增加有利于改善前池面层流态,且减弱了底层各泵机组喇叭管口吸水时水流间的相互干扰。八字形导流墩位置宜设置在扩散段处,过分靠近后壁或偏向两侧,在前池中层和面层两侧翼墙处漩涡回流现象越严重,且各泵机组吸水均匀性提升相对最大;八字形导流墩扩散角宜取18°左右,扩散角过小,两侧泵机组吸水均匀性有明显下降,扩散角过大,前池局部漩涡增多;采用45°倾斜挡板对于斜坡扩散入流方案的取水泵站前池流态改善效果显著,随着倾斜挡板位置远离后壁方向移动,前池底层流速分布更加均匀,各泵机组吸水均匀性越好。(7)不同开泵方式下,斜坡闸孔入流取水泵站前池水力特性研究。取水泵站内无措施条件下,不同的开泵方式对前池内流态的影响较小;同时运行1#、2#、3#、4#泵机组,各泵机组吸水均匀性较好,且差异较小,为无措施条件下较优运行方案。取水泵站采用优化措施后,在不同的开泵方式下,各运行方案前池底层的流线分布均较为均匀,无明显回流产生;在前池的中层存在不同程度的局部回流漩涡;在前池的面层流线分布较为均匀,且差异不明显,有局部漩涡发生在两侧倾斜壁面处;在运行方案4和运行方案3开泵方式下,各运行的泵机组吸水均匀性较高,其中运行方案4运行泵机组喇叭管入口断面流速均匀度均在72%以上,采用改善措施后的取水泵站宜采用运行方案4的开泵方式运行。
[Abstract]:The water intake and pumping station of the water source area includes the pre-settling tank, the aeration tank, the three main parts of the front tank, the flow velocity in the water taking pump station is small, the water level is large, and the internal flow pattern is disordered. When there are no hydraulic optimization measures in the water intake pump station, the flow pattern of the water in the pre-settling tank is disturbed, and the backflow area, the dead water area and the vortex are present in the aeration tank and the front pool, and the bad flow pattern in the water intake pump station can cause the local sediment deposition of the aeration tank and the front pool and the distribution of the flow velocity of the inlet pump water flow to be uneven. In this paper, by means of the CFD technology, the rectification measures of the water intake pump station in the water source field are studied, the water distribution uniformity of the front perforated flower wall of the pre-sinking pool, the overall hydraulic optimization of the pre-sinking aeration tank and the forebay are studied. And the difference of the flow characteristics of the front tank and the water absorption uniformity of the water pump in the multi-pump operation mode. The research results can provide a reference for further improving the flow pattern of water flow in the water intake pump station, preventing sediment deposition, improving the safety and high efficiency of the operation of the water pump, and providing a reference for the selection of the pump mode under the condition of multi-pump operation. (1) Using the commercial software ANSYS 14.5, the turbulence model is used to select the standard k-turbulent flow model. Based on the grid-independent analysis, the total grid number of the water intake pumping station is determined to be 175.6 million. (2) The hydraulic optimization of the perforated flower wall of the primary sedimentation tank. in that condition of different water level, the water distribution uniformity of the perforated flower wall of different form (rectangle, round and diamond) is great difference; the diamond-shaped perforated flower wall is adopted for water distribution, the flow velocity distribution of the water flow in the pre-settling tank is more uniform, and the flow state is relatively smooth, And is beneficial to the settlement of suspended solids such as sand and the like. (3) Research on the flow characteristics of the water intake pump station. For the inlet water intake pump station of the slope gate and the free inflow water intake pump station of the slope, the internal state of the water intake pump station is more disordered under the condition of no measure, and there are obvious deflow, vortex and return area in the slope section at the corner of the gallery of the aeration tank, and there is a serious bias problem after the water flows into the forebay. The inlet water-taking pump station of the slope gate has a large-area swirl area in the slope section, and the water flow enters the front pool in the form of a jet to be difficult to spread evenly; the free-inflow water-taking pump station of the slope diffusion is easy to form a large-area return area in the slope section and the front pool. (4) The flow pattern of the aeration tank of the water intake pump station is improved. a U-shaped guide wall and a 1/4 arc-shaped guide wall are arranged in the corner of the gallery of the aeration tank, The generation of the back flow vortex of the slope section is weakened, so that the water flow enters the front pool relatively smoothly. (5) The flow pattern of the front pool of the inflow water intake pump station of the slope gate hole is improved. when there is no rectification measure in the front tank, the water flow directly impacts the rear wall through the form of a gate hole, a large area of reflux is formed on both sides, the water absorption uniformity of each pump unit is large, the flow rate uniformity of the inlet cross section of each pump is inverted V-shaped distribution, and the water absorption uniformity of the middle 3 # unit is high, And the water absorption uniformity of the two side units is poor. by arranging an eight-shaped guide pier at the middle line of the two gate holes in the front pool, a partition pier is arranged between the pump units, and the combination measures such as right-angle wing walls at the two sides of the front tank are changed, And the water absorption uniformity of each pump is obviously reduced. (6) The flow pattern of the front pool of the free-in-flow water-taking pump station for the slope diffusion is improved. When there is no rectification measure in the front tank, the water flow enters the front pool through the diffusion section, and the backflow area is formed on both sides of the front pool, and the local vortex occurs near the back wall of the front pool; at this time, the water absorption uniformity of each pump unit is high, and the middle unit is low. An eight-shaped guide pier is arranged between the pump units, an eight-shaped guide pier is arranged in the front pool, and combined measures such as a 45-degree inclined baffle are arranged, so that the flow state and the flow velocity distribution in the front tank are obviously improved, and the water absorption uniformity of each pump unit is improved. In which, the increase of the height of the blocking pier is beneficial to the improvement of the laminar flow state of the front pool surface, and the mutual interference between the water flows in the water absorption of the horn mouth of each pump unit of the bottom layer is reduced. The position of the eight-shaped guide pier should be set at the diffusion section, which is too close to the rear wall or to the two sides. The more serious the swirling reflux phenomenon at the wing walls at the middle and the side of the front pool, and the water absorption uniformity of each pump unit is relatively maximum; the diffusion angle of the eight-shaped guide pier is preferably about 18 degrees, the diffusion angle is too small, the water absorption uniformity of the two-side pump units is obviously reduced, the diffusion angle is too large, and the local vortex of the front pool is increased; the 45-degree inclined baffle plate is adopted for improving the flow pattern of the front pool of the water taking pump station of the slope diffusion inflow scheme, The flow velocity distribution of the bottom layer of the front pool is more uniform, and the water absorption uniformity of each pump unit is better. (7) The hydraulic characteristics of the front pool of the inflow water intake pump station of the slope gate are studied in different open-pump modes. Under the condition of no measure in the water intake pump station, the effect of different open-pump methods on the flow pattern in the front pool is small; at the same time,1 #,2 #,3 # and 4 # pump units are operated, and the water absorption uniformity of each pump unit is good, and the difference is small, and the operation scheme is better under the condition of no measure. After the water intake pump station adopts the optimization measures, the flow line distribution of the bottom layer of the front pool of each operation scheme is uniform, no obvious backflow is generated under different open pump modes, the middle layer of the front pool is provided with a local reflux vortex at different degrees, and the surface layer streamline distribution of the front pool is more uniform, in that pump mode of the operation scheme 4 and the operation scheme 3, the water absorption uniformity of each operation pump unit is high, wherein the flow rate uniformity of the inlet section of the horn pipe of the operation scheme 4 is more than 72 percent, The water-taking pump station after the improvement measures should be operated in the open-pump mode of the operation scheme 4.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV675
，
本文编号：2502999
[Abstract]:The water intake and pumping station of the water source area includes the pre-settling tank, the aeration tank, the three main parts of the front tank, the flow velocity in the water taking pump station is small, the water level is large, and the internal flow pattern is disordered. When there are no hydraulic optimization measures in the water intake pump station, the flow pattern of the water in the pre-settling tank is disturbed, and the backflow area, the dead water area and the vortex are present in the aeration tank and the front pool, and the bad flow pattern in the water intake pump station can cause the local sediment deposition of the aeration tank and the front pool and the distribution of the flow velocity of the inlet pump water flow to be uneven. In this paper, by means of the CFD technology, the rectification measures of the water intake pump station in the water source field are studied, the water distribution uniformity of the front perforated flower wall of the pre-sinking pool, the overall hydraulic optimization of the pre-sinking aeration tank and the forebay are studied. And the difference of the flow characteristics of the front tank and the water absorption uniformity of the water pump in the multi-pump operation mode. The research results can provide a reference for further improving the flow pattern of water flow in the water intake pump station, preventing sediment deposition, improving the safety and high efficiency of the operation of the water pump, and providing a reference for the selection of the pump mode under the condition of multi-pump operation. (1) Using the commercial software ANSYS 14.5, the turbulence model is used to select the standard k-turbulent flow model. Based on the grid-independent analysis, the total grid number of the water intake pumping station is determined to be 175.6 million. (2) The hydraulic optimization of the perforated flower wall of the primary sedimentation tank. in that condition of different water level, the water distribution uniformity of the perforated flower wall of different form (rectangle, round and diamond) is great difference; the diamond-shaped perforated flower wall is adopted for water distribution, the flow velocity distribution of the water flow in the pre-settling tank is more uniform, and the flow state is relatively smooth, And is beneficial to the settlement of suspended solids such as sand and the like. (3) Research on the flow characteristics of the water intake pump station. For the inlet water intake pump station of the slope gate and the free inflow water intake pump station of the slope, the internal state of the water intake pump station is more disordered under the condition of no measure, and there are obvious deflow, vortex and return area in the slope section at the corner of the gallery of the aeration tank, and there is a serious bias problem after the water flows into the forebay. The inlet water-taking pump station of the slope gate has a large-area swirl area in the slope section, and the water flow enters the front pool in the form of a jet to be difficult to spread evenly; the free-inflow water-taking pump station of the slope diffusion is easy to form a large-area return area in the slope section and the front pool. (4) The flow pattern of the aeration tank of the water intake pump station is improved. a U-shaped guide wall and a 1/4 arc-shaped guide wall are arranged in the corner of the gallery of the aeration tank, The generation of the back flow vortex of the slope section is weakened, so that the water flow enters the front pool relatively smoothly. (5) The flow pattern of the front pool of the inflow water intake pump station of the slope gate hole is improved. when there is no rectification measure in the front tank, the water flow directly impacts the rear wall through the form of a gate hole, a large area of reflux is formed on both sides, the water absorption uniformity of each pump unit is large, the flow rate uniformity of the inlet cross section of each pump is inverted V-shaped distribution, and the water absorption uniformity of the middle 3 # unit is high, And the water absorption uniformity of the two side units is poor. by arranging an eight-shaped guide pier at the middle line of the two gate holes in the front pool, a partition pier is arranged between the pump units, and the combination measures such as right-angle wing walls at the two sides of the front tank are changed, And the water absorption uniformity of each pump is obviously reduced. (6) The flow pattern of the front pool of the free-in-flow water-taking pump station for the slope diffusion is improved. When there is no rectification measure in the front tank, the water flow enters the front pool through the diffusion section, and the backflow area is formed on both sides of the front pool, and the local vortex occurs near the back wall of the front pool; at this time, the water absorption uniformity of each pump unit is high, and the middle unit is low. An eight-shaped guide pier is arranged between the pump units, an eight-shaped guide pier is arranged in the front pool, and combined measures such as a 45-degree inclined baffle are arranged, so that the flow state and the flow velocity distribution in the front tank are obviously improved, and the water absorption uniformity of each pump unit is improved. In which, the increase of the height of the blocking pier is beneficial to the improvement of the laminar flow state of the front pool surface, and the mutual interference between the water flows in the water absorption of the horn mouth of each pump unit of the bottom layer is reduced. The position of the eight-shaped guide pier should be set at the diffusion section, which is too close to the rear wall or to the two sides. The more serious the swirling reflux phenomenon at the wing walls at the middle and the side of the front pool, and the water absorption uniformity of each pump unit is relatively maximum; the diffusion angle of the eight-shaped guide pier is preferably about 18 degrees, the diffusion angle is too small, the water absorption uniformity of the two-side pump units is obviously reduced, the diffusion angle is too large, and the local vortex of the front pool is increased; the 45-degree inclined baffle plate is adopted for improving the flow pattern of the front pool of the water taking pump station of the slope diffusion inflow scheme, The flow velocity distribution of the bottom layer of the front pool is more uniform, and the water absorption uniformity of each pump unit is better. (7) The hydraulic characteristics of the front pool of the inflow water intake pump station of the slope gate are studied in different open-pump modes. Under the condition of no measure in the water intake pump station, the effect of different open-pump methods on the flow pattern in the front pool is small; at the same time,1 #,2 #,3 # and 4 # pump units are operated, and the water absorption uniformity of each pump unit is good, and the difference is small, and the operation scheme is better under the condition of no measure. After the water intake pump station adopts the optimization measures, the flow line distribution of the bottom layer of the front pool of each operation scheme is uniform, no obvious backflow is generated under different open pump modes, the middle layer of the front pool is provided with a local reflux vortex at different degrees, and the surface layer streamline distribution of the front pool is more uniform, in that pump mode of the operation scheme 4 and the operation scheme 3, the water absorption uniformity of each operation pump unit is high, wherein the flow rate uniformity of the inlet section of the horn pipe of the operation scheme 4 is more than 72 percent, The water-taking pump station after the improvement measures should be operated in the open-pump mode of the operation scheme 4.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV675
，
本文编号：2502999
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