天然河道浑水流速分布研究

A Study on the Velocity Distribution of Sedimont-Laden Flow in Natural River

通过对有关学者得出的几个典型的垂线流速分布公式的分析认为:现有的用于天然河道的流速分布公式都存在不同程度的缺陷,且这些公式仅能用来计算不受侧壁影响的二维情况下的垂线流速分布,当用于峡谷河段时计算值与实测值差别较大。实测资料表明,对数或指数型流速分布公式可用于描述宽谷河段的垂线流速分布。由水流阻力公式导得了天然河道垂线平均流速沿横向的分布,引进重线流速分布,即得到断面点流速的分布公式。公式既可以用于清水水流,也可以用于挟有泥沙的浑水水流,含沙量对流速分布的影响主要反映在指数m发生变化这一点上。与实测资料比较发现,公式较好地反映了天然河道流速分布的实际情况。

Based on the analysis of several typical expressions for vertical velocity distributions obtained by scholars concerned, we hold that all present formulae for velocity distributions in natural river have some defects of certain degree and these formulae can only be used to calculate two demensional vertical velocity distribution which does not be affected byside boundaries. There is a considerable disparity between the calculated and the measured if the calculating reach is a gorge reach. The measured data show that the logarithmic and the exponential velocity distribution formulae can be used to describe the vertical velocity distribution in straight reach. From the flow resistance formula, the transverse distribution of the vertical mean velocity in natural river can be obtained, and the point velocity distribution formula of a transversal section can be also gained by use of vertical velocity distribution. The formula can be appliod to either clear coater flow or sediment-laden flow. The influence of sedimentation to the velocity distribution is reflected on the variation of the exponent m. It has been found by comparing the calculated result coith the measured result that the formula can reflect the reality of the velocity distribution.