台阶式溢洪道相对消能率与相对佛汝德数关系研究

台阶式溢洪道是目前研究的热点,台阶消能率和佛汝德数是重要的水力参数。将台阶式溢洪道佛汝德数与对应光滑溢洪道佛汝德数对比,引入相对佛汝德数的概念,准确地反映由于台阶的存在对水流佛汝德数的改变值。通过对0.5,1.0,2.0 m 这3个不同台阶高度,坡度为38.66°的台阶式溢洪道进行试验研究,探讨了相对佛汝德数和相对消能率之间的关系。结果表明非均匀流流态下相对佛汝德数和相对消能率表现出良好线性关系,相关系数为0.992 7~0.998 9。单宽流量不同,相对佛汝德数和相对消能率对应直线的斜率明显不同,其斜率随单宽流量加大而增大;而台阶高度变化对相对佛汝德数和相对消能率线性关系的直线斜率影响很小。

Relation Between Relative Energy Dissipation Ratio and Relative Froude Number of Stepped Spillway

Stepped spillways have gained significant interest and popularity among researchers. Energy dissipation rate and Froude number are important hydraulic parameters. In this paper we introduce the concept of relative Froude number of stepped spillway which reflects the effect of step on the value of Froude number through comparing the Froude number of stepped spillway and the corresponding Froude number of smooth spillway. Through tests on stepped spillways (with different step heights 0.5m, 1.0m, 2.0m and chute angle 38.66°), we investigate the relation between relative Froude number and relative rate of energy dissipation. Results show that in non-uniform flow the relative Froude number is in linear relation with relative rate of energy dissipation, and the correlation coefficient is 0.9927-0.9989. Further study shows that the slope of the linear relation increases with the increase of unit width discharge, but the height of step has only slight effect on the slope of the linear relation between relative Froude number and relative ratio of energy dissipation.