窄缝挑坎射流轨迹及扩散特性试验研究

Study of Jet trajectory and diffusion characteristics of slit-type bucket

窄缝挑流消能工由于投资少、工程量小,在高坝大流量泄洪建筑物中应用广泛。窄缝挑坎通过纵向扩散水舌的方式进行消能,以优化窄缝挑坎体型为目的,文章基于某水电枢纽物理模型试验,通过调整出口宽度大小的方式控制出口断面高宽比,系统分析出口断面高宽比、流量等对挑射轨迹的影响。研究结果表明,出口断面高宽比是影响水舌挑距的重要因素,射流扩散程度随出口断面高宽比的增加而增大,高宽比增大到一定程度后可清晰地观测到水翅与水帘现象。基于试验测量数据,对学者提出的水舌预测轨迹经验公式进行修正,修正后的公式在一定程度上提高了预测精度,研究成果可供类似工程参考。

Slit-type energy dissipator were widely used in high flow flood relief buildings in high dams due to the low investment and small volume of work.Longitudinal diffusion of the water tongue was used by the slit-type bucket(STB)to optimize the shape of STB.This paper was based on a physical model test of a hydropower hub.Outlet orifice widths(b)were adjusted to control width to height ratio of pick flow(λ)and,in addition,the effect ofλand flow rates(Q)on throw distance was investigated.A delicate investigation shows that an important factor affecting the throw distance of the water tongue isλ,the diffusion of the jet increases with the additions ofλ,whenλincreases to a certain level the water wings and water curtain phenomenon can be clearly observed.Based on experimental measurement data,empirical formulas for predicting the trajectory of water tongues proposed by previous authors have been modified based on the experimental data in this paper and improved the prediction accuracy to a certain extent.Results can be used as a reference for similar projects.