Two-Phase Flow Characteristics of Stepped Spillways
Two-Phase Flow Characteristics of Stepped Spillways
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DOI：
10.1061/(asce)0733-9429(2003)129:9(661
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发表时间：
2003-09
影响因子：
2.4
通讯作者：
R. Boes;W. Hager
中科院分区：
文献类型：
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作者：
R. Boes;W. Hager
一个大型模型水槽与光纤仪器的实验研究表明，最低雷诺数和韦伯数约10 - 5和100，分别需要粘度和表面张力的影响变得可以忽略不计相比，重力和惯性力表示的弗劳德相似。掺气起始点的位置和流深都可以表示为包含单位流量、台阶高度和斜槽角度的所谓粗糙度弗劳德数的函数。深度平均的空气浓度被发现只依赖于一个归一化的垂直距离从溢洪道顶部和斜槽的角度范围从堤坝到重力坝溢洪道的斜槽斜坡。空气浓度分布可用气泡扩散模型表示。拟底空气浓度允许评估阶梯式泄槽的空化风险，并通过回归函数近似。最后，提出了一种新的速度分布函数，该函数在特征无因次混合深度的80%以内为幂律，在此之上为常数。
An experimental study on a large model flume with fiber-optical instrumentation indicated that minimum Reynolds and Weber numbers of about 10 5 and 100, respectively, are required for viscosity and surface tension effects to become negligible compared to gravitational and inertial forces expressed by Froude similitude. Both the location of and the flow depth at the inception point of air entrainment can be expressed as functions of a so-called roughness Froude number containing the unit discharge, step height and chute angle. The depth-averaged air concentration is found to depend only on a normalized vertical distance from the spillway crest and the chute angle for chute slopes ranging from embankment to gravity dam spillways. Air concentration profiles can be expressed by an air bubble diffusion model. The pseudobottom air concentration allows the assessment of the cavitation risk of stepped chutes and is approximated by a regression function. Finally, a new velocity distribution function is presented consisting of a power law up to 80% of the characteristic nondimensional mixture depth, and a constant value above.