台阶式溢洪道滑行流相对水力特性规律研究

台阶式溢洪道消能效果显著、能大大减小下游消力池的尺寸、节省工程量和投资,但其水流规律复杂。本文对比研究了台阶式溢洪道和同体型的光滑溢洪道,并引入台阶式溢洪道相对流速、相对弗劳德数、相对消能率等3个相对水力参数。通过模型试验,分析了台阶式溢洪道流速、弗劳德数、消能率等常规水力参数及3个相对水力参数沿程变化规律、相对临界水深及溢洪道坡度对常规及相对水力参数的影响。分析结果表明:台阶式溢洪道常规水力参数沿程呈复杂的曲线变化规律,相对临界水深及坡度对常规水力参数的影响亦较为复杂,不便应用;台阶式溢洪道相对水力参数沿程表现出良好的线性相关关系,相关系数平均值为0.9887～0.9944;相对水力参数均随相对临界水深的增大而减小,随溢洪道坡度的增大而增大。通过对台阶式溢洪道相对水力参数沿程线性规律的定量分析,并结合光滑溢洪道成熟的水力计算理论,可为台阶式溢洪道复杂水力特性计算提供新方法。

Study on the relative hydraulic characteristics of skimming flow on stepped spillways

The stepped spillway has remarkable energy dissipation effect,can greatly reduce the size of the downstream stilling basin, and save the engineering quantity and investment, but the flow characteristics is complex. Three relative hydraulic parameters of stepped spillway such as relative velocity, relative Froude number and relative energy dissipation rate are introduced by comparing stepped spillway with smooth spillway of the same shape. Through three different model tests, the variation law of three conventional hydraulic parameters such as velocity,Froude number,energy dissipation rate and three relative hydraulic parameters along the stepped spillway,and the influence of relative critical water depth and spillway slope on conventional and relative hydraulic parameters are analyzed. The results show that the conventional hydraulic parameters of stepped spillway are complicated along the way and the influence of relative critical water depth and spillway slope on conventional hydraulic parameters is also complex, which are inconvenient for application. The relative hydraulic parameters of stepped spillway show good linear correlation along the way, with the average correlation coefficient ranging from 0.9887 to 0.9944. The relative hydraulic parameters decrease with the increase of the relative critical water depth, and increase with the increase of the spillway slope. Through quantitative analysis of linear characteristics of relative hydraulic parameters along the stepped spillway, and combined with the mature hydraulic calculation theory of smooth spillway, a new method can be provided for the calculation of complex hydraulic characteristics of stepped spillway.