台阶式溢洪道阶顶过流断面弗劳德数沿程变化研究

弗劳德数是明渠水流的重要水力参数,但在台阶式溢洪道中尚无系统研究成果。本文将台阶式溢洪道弗劳德数和对应光滑溢洪道弗劳德数对比,引入相对弗劳德数概念。通过26.57?、32.01?、38.66?和51.3?四组不同坡度,0.5~2.0m不同台阶高度的15组模型试验,分析了非均匀流段台阶式溢洪道弗劳德数及相对弗劳德数与流程长度、单宽流量、台阶高度、坡度、相对消能水头之间的关系。台阶式溢洪道弗劳德数与这些参数关系复杂,不便分析应用,而台阶式溢洪道相对弗劳德数和这些参数呈良好线性关系,试验结果证实了引入台阶式溢洪道相对弗劳德数的必要性。

Study on relative Froude number over steps of stepped spillways

Froude number is an key parameter in open channel flows, but its systematic research of flows over stepped spillways is lacking. This paper presents a relative Froude number concept for stepped spillways by comparing their Froude numbers with those of the corresponding smooth chutes. We have conducted experimental tests of fifteen sets on a model stepped spillway using four different channel slopes (26.57°, 32.01°, 38.66° and 51.3°) and different step heights (0.5~2.0 m). Analysis of the test data shows that for a smooth-bottom chute, the Froude number of its non-uniform flow section takes good linear relations with flow length, unit width discharge, step height, slope, and relative energy dissipation head, while for a stepped spillway, the relations are complicated and difficult to apply. This experiment proves the necessity of stepped spillway analysis adopting relative Froude number.