Laboratory experiments were carried out to study the scouring of sand beds by vertically impinging submerged circular turbulent water jets with short impinging height of 5.5 times the jet diameter. Measurements of the profiles of the static scour hole at different times were made along with the dynamic scour depths using a novel experimental arrangement. It was found that the asymptotic characteristic lengths of the scour hole can be predicted using the erosion parameter, E_c, of short impinging jet experiments. The ratio of the dynamic to static scour depths in asymptotic state varies between 2.1 and 4.3, for E_c ranges between 3 and 28. Semi-empirical prediction equations are developed for the asymptotic lengths and empirical equations are developed for the temporal development of the characteristic lengths. These equations show good correlations, with the coefficient of correlation (R²) varying beween 0.83 and 0.98. The shape of the dimensionless asymptotic scour hole is found to be different for short and long impinging jets. A general equation for its shape is developed considering the shape as a function of the submerged angle of repose of the bed material.

中文翻译：

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通过短冲击湍流射流冲刷砂床

进行了实验室实验，研究了垂直撞击水下圆形湍流水射流对砂床的冲刷，短撞击高度为射流直径的 5.5 倍。使用新颖的实验装置对不同时间的静态冲刷孔轮廓以及动态冲刷深度进行了测量。发现冲刷孔的渐近特征长度可以使用短冲击射流实验的侵蚀参数E _c来预测。渐近状态下动态与静态冲刷深度的比率在 2.1 和 4.3 之间变化，对于E _c范围在 3 到 28 之间。为渐近长度开发了半经验预测方程，为特征长度的时间开发开发了经验方程。这些方程显示出良好的相关性，相关系数 ( R ² ) 在 0.83 和 0.98 之间变化。发现无量纲渐近冲刷孔的形状对于短的和长的撞击射流是不同的。考虑到作为床层材料的浸没休止角的函数的形状，开发了其形状的一般方程。