光滑床面薄层水流水动力特性试验研究

Experiment Study on Hydraulic Properties of Overland Flow Under the Smooth Surface

为揭示坡面薄层水流水动力学参数变化的内在规律和坡面流土壤侵蚀机理,基于光滑床面薄层水流试验,研究了流速、雷诺数、弗劳德数、阻力系数、水流功率等水动力学参数随坡度和流量的变化规律。在坡角为0°~12°、单宽流量为0.04~0.24 L/(s·m)条件下的光滑床面水槽试验表明:坡面薄层水流雷诺数、弗劳德数、水流功率均与坡度和单宽流量呈幂函数递增关系,雷诺数受单宽流量影响较大、受坡度影响较小,坡度和单宽流量对弗劳德数的影响相当,水流功率的主要影响因素是坡度;阻力系数与坡度和单宽流量呈幂函数递减关系,单宽流量为主要影响因素、坡度为次要影响因素,坡角≤5°时坡度对阻力系数的影响可忽略不计,坡角≥10°时坡度对阻力系数的影响不可忽视;该试验条件下坡面流以急流为主,在坡角小于2°时才会出现临界流或缓流。

In order to reveal the changes for the inherent laws of overland flow hydraulic characteristic and the mechanism of slope flow soil erosion,based on experiments of overland flow in a smooth hydraulic flume,the relationship between dynamics parameters(flow velocity,Reynolds number(Re),Froude number(Fr),friction factor and stream power)and the variation of hydrodynamic parameters with slope and discharge was studied.Based on the experiments of overland flow in a smooth hydraulic flume,when the slope is 0°-12°,and unit width dis⁃charge is 0.04-0.24 L/(s·m),the results show that the Re,Fr and stream power is a power function growth with the increasing of dis⁃charge and slope gradient.Re is greatly affected by the unit width discharge,and slightly affected by slope gradient;discharge and slope gra⁃dient have the same effect on Fr;the main influencing factor of stream power is slope gradient.The friction factor is a power function reduc⁃tion with the increasing of discharge and slope gradient,the determined influence to friction factor is discharge,slope gradient is second.When the slope gradient is less than 5 degrees,discharge is a single control factor,but when the slope gradient is greater than 10 degrees,the impact of slope gradient on friction factor can’t be ignored.Under the test conditions,its main flow patter is torrent flow and when the slope gradient is less than 2 degrees,the flow regime is laminar flow or transition flow.