水下移动射流冲蚀沙床的试验研究
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摘要
为研究移动射流冲蚀效果和泥沙输移的影响因素,开展了不同射流喷嘴移动速度和沙床坡度条件下的二维平面移动射流冲蚀沙床试验研究。试验记录了不同射流工况下的泥沙输移过程及异重流的运动规律,分析了泥沙输移及异重流运动随射流喷嘴移动速度、沙床坡度的变化规律,讨论了异重流运动和泥沙淤积形态的物理机制。结果表明:水下移动射流冲蚀沙床能够形成异重流,可实现淤积泥沙的起动并输移一定距离。泥沙淤积轮廓剖面具有相似性,各工况平均输移距离近似相等,沿程累计泥沙相对输移量分布与泥沙粒径分布相似。泥沙相对输移量与射流喷嘴移动速度和沙床坡度呈正相关,但当沙床坡度大于10‰后,坡度影响不再显著。
A series of experiments on two-dimensional plane jet erosion sand bed were carried out to study the erosion effects of sand bed by underwater moving jets. The jet movement speed and sand bed slopes were changed. The sediment transportation and density flow under different jet conditions were recorded. According to experimental results, the variation law of sediment transportation and density flow movement with jet movement speed and sand bed slope were analyzed. The physical mechanisms of the two-phase flow movement and sedimentation morphology were discussed. Results show that the moving jet erosion of sand bed formed density current, which could induce sediment incipience and transport a certain distance. The sediment deposition profiles after the erosion were similar, and the averaged transport distances in all conditions were approximately equal. There was similar relationship between accumulated relative sediment volume distribution and sand particle size distribution. The relative amount of sediment transport was positively correlated with the jet moving speed and the sand bed slope, but when the slope was greater than 10 ‰, the slope effect was no longer significant.
A series of experiments on two-dimensional plane jet erosion sand bed were carried out to study the erosion effects of sand bed by underwater moving jets. The jet movement speed and sand bed slopes were changed. The sediment transportation and density flow under different jet conditions were recorded. According to experimental results, the variation law of sediment transportation and density flow movement with jet movement speed and sand bed slope were analyzed. The physical mechanisms of the two-phase flow movement and sedimentation morphology were discussed. Results show that the moving jet erosion of sand bed formed density current, which could induce sediment incipience and transport a certain distance. The sediment deposition profiles after the erosion were similar, and the averaged transport distances in all conditions were approximately equal. There was similar relationship between accumulated relative sediment volume distribution and sand particle size distribution. The relative amount of sediment transport was positively correlated with the jet moving speed and the sand bed slope, but when the slope was greater than 10 ‰, the slope effect was no longer significant.
引文
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[4] 罗肇森,罗勇.一种治沙输沙的新理念和方法[J].泥沙研究,2009(4):31-38.
[5] 王新宏,龚立尧,吴巍,等.高含沙河流供水水库运用方式研究——以王瑶水库为例[J].泥沙研究,2018,43(2):33-39.
[6] Camille Scuria Fontana.Faster and cheaper water injection dredging [J].Mechanical Engineering,1994,116(4):22.
[7] Spencer K L,Dewhurst R E,Penna P.Potential impacts of water injection dredging on water quality and ecotoxicity in Limehouse Basin,River Thames,SE England,UK [J].Chemosphere,2006,63(3):509-521.
[8] 张原锋,张隆荣.射流冲刷试验及其在黄河潼关河段的应用[J].水利水电技术,2004,35(12):19-22.
[9] 李文学,张隆荣,姜乃迁,等.射流冲刷试验研究(之二)[J].泥沙研究,2000(5):22-27.
[10] 宁锋,高传昌,王为术.基于脉冲射流的小浪底水库人工异重流输沙方法探讨[J].南水北调与水利科技,2007(2):75-77.
[11] 顾磊,倪福生,徐立群,等.垂直射流冲刷砂床的喷嘴间距试验研究[J].泥沙研究,2017,42(3):54-58.
[12] Perng A T H,Capart H.Underwater sand bed erosion and internal jump formation by travelling plane jets [J].Journal of Fluid Mechanics,2008,595(595):1-43.
[13] 白志刚,孟然,唐立志,等.喷射式水下挖沟机冲刷试验[J].中国海洋平台,2011,26(6):35-38.
[14] 张芝永,员鹏,吴修广,等.移动射流冲刷数值模拟研究[C]//第十三届全国水动力学学术会议暨第二十六届全国水动力学研讨会文集——G海岸环境与地球物理流体力学,2014:10-15.
[15] Zordan J,Juez C,Schleiss A J,et al.Entrainment,transport and deposition of sediment by saline gravity currents [J].Advances in Water Resources.Advances Water Resource,2018,115:17-32.
[16] 丛鑫,边振,薛春珂,等.不同坡度条件下的水土流失特征研究[J].中国农村水利水电,2017(5):124-128.