非对称河道窄缝挑流轨迹及冲刷规律试验研究

Experimental Study on Jet Trajectories and Scour Regularities ofNarrow Slit-bucket in Asymmetrical River

基于某水电站模型试验,系统探究了非对称河道内不同收缩比窄缝消能工的挑流轨迹和冲刷规律。研究表明窄缝挑坎出口的收缩比对冲刷坑的形态影响明显,随着收缩比的减小,挑坎两边的侧墙将水流向中间挤压,同时出射水舌在空气中充分扩散,进一步掺气消能,导致冲刷坑的深度降低、范围增大。对于非对称河床,相同流量下河床冲深会随着β增大而加大,但其冲刷横向扩散范围会显著减小。对水舌外缘挑距的公式开展了对比研究,当收缩比β>0.2时,陈忠儒公式的计算结果与试验值吻合;当β=0.2时挑流轨迹计算应采用修正后的水工计算手册公式。

The jet trajectory and scour characteristics of a narrow slit-bucket with different shrinkage ratios in an asymmetric river channel were examined via model test of a hydropower station.The findings demonstrate that the shrinkage ratio of the narrow slit-bucket significantly influences the morphology of the scour pit.As the shrinkage ratio decreases,the sidewalls of the bucket constrict the water flow,while the jet disperses more effectively in the air,thus increasing energy dissipation,and consequently resulting in a decrease in scour pit depth and an increase in scour extent.For asymmetric riverbeds,the scour depth amplifies with an increasingβvalue at a given flow rate.However,the lateral spread of scour notably reduces.Furthermore,a comparative analysis was conducted to calculate the jet trajectory.The results reveal that the calculation result of Chen Zhongru’s formula agrees well with test values when shrinkage ratio(β)is greater than 0.2.Whenβ=0.2,the modified formula from the hydraulic calculation manual proves to be a better choice for calculating the jet trajectory.