丁坝群对弯道水力特性影响的数值模拟研究
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摘要
弯道螺旋流是弯道水流的特点之一,弯道环流会造成凸岸发生淤积,凹岸遭受冲刷,对护岸工程非常不利。在弯道中布设丁坝可有效减弱弯道螺旋流强度,改善水流流态,保护岸坡稳定。采用RNG k-ε湍流模型,应用VOF法捕捉自由水面,采用半隐式SIMPLE算法求解速度与压力耦合方程组,模拟在60°弯道内布设丁坝群后弯道水流特性。研究表明:数值模拟的水位、流速和试验数值据吻合良好。弯道内设置丁坝群后,可有效改善凹岸区域的冲刷及凸岸的淤积,主河槽的水深增加,水面横比降减小,说明丁坝群的布置在稳定弯道水流,防止岸坡冲於方面有较好的效果。
The spiral flow in bends can easily causes a problem of river erosion at concave banks and sediment deposition at convex banks in actual bend rivers,and is unfavorable for bank protection engineering. The spur-dikes can effectively control the spiral flow and improve the flow patterns in bends. The time-averaged equations closed with the RNG k-ε turbulence model were used to simulate the flows in bends to analyze the function of spur-dikes in bends. The VOF( Volume of fluid) method was applied to track the flow free surface. The velocity and pressure coupling equations were solved by the SIMPLE algorithm. The predicted water level and velocity distributions in the bend showed a good agreement with experimental data. The spur-dikes can effectively eliminate the problem of river erosion at concave bank and sediment deposition at convex bank in the bend channel,increase the water level in the main channel,and decrease transverse slope of free surface. It can be concluded that the layout of spur dikes is effective in stabilizing the bend flow and preventing bank slope from rushing.
The spiral flow in bends can easily causes a problem of river erosion at concave banks and sediment deposition at convex banks in actual bend rivers,and is unfavorable for bank protection engineering. The spur-dikes can effectively control the spiral flow and improve the flow patterns in bends. The time-averaged equations closed with the RNG k-ε turbulence model were used to simulate the flows in bends to analyze the function of spur-dikes in bends. The VOF( Volume of fluid) method was applied to track the flow free surface. The velocity and pressure coupling equations were solved by the SIMPLE algorithm. The predicted water level and velocity distributions in the bend showed a good agreement with experimental data. The spur-dikes can effectively eliminate the problem of river erosion at concave bank and sediment deposition at convex bank in the bend channel,increase the water level in the main channel,and decrease transverse slope of free surface. It can be concluded that the layout of spur dikes is effective in stabilizing the bend flow and preventing bank slope from rushing.
引文
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[2]杨程.不同弯度水渠二维水流运动数值模拟研究[J].宁夏工程技术,2015,14(2):132-137.
[3]ZHU Chuanjie,GAO Zishan,LIN Baiquan,et al. Flame acceleration in pipes containing bends of different angles[J].Journal of Loss Prevention in the Process Industries,2016,43:273-279.
[4]MAZHAR H,EWING D,COTTON J S,et al. Measurement of the flow field characteristics in single and dual S-shape 90°bends using matched refractive index PIV[J]. Experimental Thermal and Fluid Science,2016,79:65-73.
[5]白玉川,高术仙,徐国强.常曲率U型弯道水流紊动特性试验研究[J].水利水电技术,2015,46(11):134-137.
[6]吴华莉,张小峰,金中武,等.四种紊流模型模拟弯道水流精度的对比分析[J].深圳大学学报(理工版),2015,32(5):506-514.
[7]魏文礼,洪云飞,吕彬,等.复式断面明渠弯道水流三维雷诺应力模型数值模拟[J].应用力学学报,2015,32(4):604-610+705.
[8]魏文礼,蔡亚希.淹没丁坝三维水流数值模拟研究[J].水资源与水工程学报,2014,25(3):43-47.
[9]MOHAMMAD V,YASER S,SHAKER H S. Effects of distance between the T-shaped spur dikes on flow and scour patterns in 90°bend using the SSIIM model[J]. Ain Shams Engineering Journal,2016,7(1):31-45.
[10]DUAN J G,HE Li,FU Xudong,et al. Mean flow and turbulence around experimental spur dike[J]. Advances in Water Resources,2009,32(12):1717-1725.
[11]苏伟,王平义,胡宝月.丁坝周围水流紊动特性与地形冲刷的关系[J].水运工程,2016(4):129-135.
[12]杨静,张潆元,冯金朝,等.考虑水流紊动的丁坝下游回流区水流挟沙力研究[J].中央民族大学学报(自然科学版),2016,25(2):53-57.
[13]周阳.丁坝对弯道水流流态影响的试验研究[D].沈阳:沈阳农业大学,2006.
[14]周俊波,刘洋. FLUENT 6. 3流场分析从入门到精通[M].北京:机械工业出版社,2012.
[15]魏文礼,戴会超.紊流模型理论及工程应用[M].西安:陕西科学技术出版社,2006.
[16]程昌华,刘建新.丁坝勾长比对坝头冲淤特性的影响[J].重庆交通学院学报,1994,13(3):75-82.