壅水条件下水流阻力试验研究

壅水条件下的水流阻力及输沙特性,在水利工程的应用中占有十分重要的位置。对壅水条件下河道开展概化水槽试验,采用声学多普勒测速仪ADV对水流流速进行了测量,并对壅水条件下水流阻力和床面切应力等进行了分析。结果表明:壅水条件下,水流流速沿垂线分布较均匀流条件下更加均匀,当壅水程度越大时,水流流速沿垂线分布越均匀,且流速分布大致上仍服从对数率分布;壅水条件下,随着水深的增大,摩阻流速不断减小;壅水条件下河道水流阻力系数随着非均匀系数及水力半径的增大而增大;引入壅水程度指标,并拟合得到了床面切应力随壅水程度指标的变化关系式。成果可为壅水条件下水流结构特征及输沙规律的研究提供参考。

Experimental Research on Flow Resistance in the Presence of Backwater

The flow resistance and sediment transport in backwater condition is very important in hydraulic engineer-ing.Through generalized flume experiment,we measured the flow velocity using Acoustic Doppler Velocimeter (ADV)and analysed the flow resistance and bed shear stress in the presence of backwater in river channel.Result shows that in backwater condition,the velocity distribution along vertical direction is much more homogeneous than that in uniform flow condition.The coefficient for describing the non-uniform flow increases when backwater intensi-fies,but still follows the logarithmic distribution.Friction velocity decreases with the depth of water increases,and the flow resistance increases with hydraulic radius and the coefficient for describing the non-uniform flow.Finally a formula is fitted between the bed shear stress index and the backwater degree index.