【摘要】 单一明渠水流由于边壁和自由水面的影响,主流区内时均流速沿垂线方向的分布存在多种形式。本试验借用声速多普勒流速仪(Sontec-ADV),测试了不同卵砾石床沙组合条件下的床面时均流速结构。试验表明:垂线流速分布主要受床面糙度R/Ks和水流流态的双重影响,佛汝德数和相对糙度在一定程度上决定了其归属于单一对数分布还是S形曲线分布,而S型曲线的转捩位置Z/H值与相对糙度R/Ks具有较好的相关性。更多还原

【Abstract】 The mean velocity profiles in gravel open channel flow were studied by a series of flume experiments.Velocity measurements were carried out in gravel beds using an Acoustic Doppler Velocimeter.The analysis of velocity profile and flow characteristics such as froude number and relative roughness(R/Ks—the ratio of hydraulic radius and bed roughness Ks which is defined by the bed material diameter d50) were calculated.The results showed that the mean velocity profile mainly depends on froude number and relative roughness.The Log-law curve could be used to fit the mean velocity profile with the froude number Fr<0.41, and the S-curve could be used to describe the velocity profile with 2.0R/Ks5.9,and the transitional location could be well fitted by means of the statistic relationship between relative depth(Z/H) and R/Ks.更多还原