不同模拟糙度定床坡面集中水流水力学特性研究

Study on Hydraulic Properties of Concentrated Flow Under Different Artificial Surface Roughness

采用钢制变坡冲刷水槽,研究了5种模拟糙度以及不同坡度和不同流量组合下集中水流内主要水力学特性变化规律。结果表明,相同糙度情况下,雷诺数随着流量增加而明显增加,与坡度相比,流量对其流态的影响较大,但坡度对弗劳德数的影响明显大于流量;等流量和等坡度情况下,随着坡面糙度的增加,雷诺数无明显变化规律,但弗劳德数均呈不断增加的趋势。5种模拟糙度下,随着坡度的增加,各流量平均流速随坡度增加呈幂函数增加趋势,且在小流量和小坡度时各值变化较小;随着坡面糙度的增加,反映坡面流阻力指数k值具有明显的幂函数下降趋势。各流量范围内阻力系数均出现随坡度的增加而增大的趋势,且在小流量情况下增加更为明显;不同模拟糙度坡面阻力系数随着雷诺数的增加呈幂函数降低趋势。研究结果有助于从水力学角度认识不同下垫面条件下泥沙输移特性和土壤侵蚀演变过程。

Investigated the main hydraulics characteristics change law under five simulation roughness and different slopes and discharges in concentrated flow by used the steel variable slope flume.The results indicated that the Reynolds number increased with the increasing of flow rate,the discharge had obvious influences on the flow regime while slope had larger influence on Froude number in the same roughness condition.In the same discharge and slope condition,Reynolds number had no significant change,but the trend of Froude number increased with the increasing of the surface roughness.In the five simulation roughness,the mean flow velocity increased in power function with the increasing of the slope,and it had little changes in small discharges and slopes.With the increasing of the surface roughness,the index kreflected flow resistance had obvious power function declined.The friction factors increased with the increasing of slope in all discharges,especially in the small discharge.The different simulation roughness decreased in power function with the increasing of Reynolds number.The results could help to better know the sediment transport and soil erosion process under different surface forms from the hydraulics aspects.