坡面薄层流水动力学特性的实验研究

采用变坡实验水槽研究了坡面薄层水流水动力学特性——流态、流速、水深及阻力系数随流量和坡度的变化规律,实验坡度5°～25°、单宽流量为0.625×10-3～12.5×10-3m3/(s·m).研究结果表明,坡面薄层水流流态与水深密切相关,坡面流的流态基本上呈过渡流和紊流;薄层水流平均流速、水深和Darcy-Weisbach阻力系数主要受流量控制,坡度的影响并不显著,其关系均可用流量和坡度的幂函数形式模拟,相关系数(R2)分别为0.98、0.97和0.95,去掉坡度后相关系数分别下降7%、16%和3%.随着雷诺数的增大,Darcy-Weisbach阻力系数下降.当单宽流量小于0.008m3/(s·m)时,坡度对阻力系数的影响较为显著;当流量大于0.008m3/(s·m)时,阻力系数基本受流量控制.随着流量增大,阻力系数呈幂函数形式递减.

Study on hydraulic properties of shallow flow

The relationships between hydraulic property parameters(flow regime,flow velocity,mean depth and friction factor)and discharge,slope gradient were simulated in a hydraulic flume(5 m×0.4 m×0.4 m). The unit discharge varied from 0.625×10^-3/(s·m) to 12.5×10^-3m³/(s·m),and the slope gradients varied from 5° to 25°. The results indicated that there is deeply relationship between the flow regime and the flow depth. The flow mean velocity,depth and the Darcy-Weisbach friction factor(f)are mainly controlled by the discharge,and can be well simulated by a simple power function of unit discharge and slope gradient. The determination coefficient are 0.98,0.97 and 0.95 respectively1 When the slope gradient is cancelled,the determination coefficients only decrease 7%,16% and 3%. When the Reynolds number increases,the Darcy 2Weisbach friction factor decreases as fine power function1 The influence of slope gradient on f depends on the discharge.