人工加糙床面薄层滚波流水力学特性试验

为了探求坡面薄层水流水力特性，从流体力学与泥沙运动学观点出发，研究均匀粗糙尺度床面（人工加糙粒径为0.380 mm），5种不同坡度和17种单宽流量下坡面薄层水流水力学参数变化规律。结果表明：坡面薄层水流流态指数在0.33~0.43之间变化，水力关系可用流态指数综合反映；滚波流速随着流量增加逐渐增加，坡度对其影响较小；波长随着流量呈单驼峰形式变化，即先随流量的增加而增加，达到峰值后又减小，峰值对应的单宽流量为0.278 L/(s·m)；滚波频率随流程的增加逐渐衰减，同时随着单宽流量的增加，平均衰减系数增大；试验条件下层流失稳产生的临界弗劳德数在0.64左右，紊流失稳临界弗劳德数在2.13左右。

Experiments on hydraulic characteristics of roll wave for sheet flow with artificial rough bed

In order to investigate hydraulic characteristics of slope shallow flow, changes in hydraulic parameters of slope shallow flow on the bed with uniform roughness (artificial roughness of 0.3850 mm in diameter) at 5 slope gradients and 17 unit width discharges were studied from the viewpoint of fluid mechanics and sediment transport mechanics. Results showed that indexes of flow regime for slope shallow flow varied from 0.33 to 0.43 and the indexes can be used to indicate some hydraulic relationships comprehensively. Velocity of rolling wave flow increased with discharge increase and was affected by gradient slightly. Wave length changed with discharge in the form of single peak, i.e., it increased with discharge increase at first and then decreased after the single peak. The peak was corresponding to the unit width discharge of 0.278 L/(s·m). The frequency of rolling wave decreased with increasing flow path length and the averaged attenuation coefficient of frequency raised with unit width discharge increase.. Under the experiment conditions, the critical Froude number for unstable laminar flow was about 0.64 and the critical Froude number for the unstable turbulent flow was about 2.13.