台阶式溢洪道滑行水流的相对水头

为了研究台阶式溢洪道的消能特性,将台阶溢洪道与光滑溢洪道沿程的总水头进行对比,引入台阶式溢洪道相对水头的概念.通过3个工程的台阶式溢洪道模型试验,坡度为1 ∶2.0~1 ∶0.9,台阶高度为0.5~2.0 m,对影响相对水头的主要因素:流程长度、单宽流量、台阶高度、坡度等进行了研究.结果表明,在滑行水流条件下,台阶式溢洪道沿程相对水头小于0;相对水头与流程长度呈良好的线性关系,相关系数为0.998 3~0.999 8;相对水头与单宽流量无关,不同流量条件同一断面的相对水头基本相等,相对误差不超过4.5%,而台阶高度、溢洪道坡度对相对水头影响较大,台阶高度越高、坡度越大,相对水头绝对值越大.试验资料证实了相对水头具有良好的水力规律,便于应用分析,可为台阶溢洪道设计提供参考.

Relative water head of skimming flow over stepped spillways

In order to study energy dissipation characteristics of stepped spillway, the water head along a stepped spillway is compared with that along a smooth spillway, and a relative hydraulic head concept is introduced in this paper. Three engineered stepped spillway models are measured with slope in range of 1 ∶2.0-1 ∶0.9 and step height ranged in 0.5-2.0 m. The effects of length of flow path, unit discharge, step height and slope on the relative head are studied. The experimental results show that the relative head all along the spillway is less than zero, indicating that the flow energy along a stepped spillway is lower than a smooth spillway. The relative head has a linear relationship with the length of flow path that is subject to a correlation coefficient between 0.998 3 and 0.999 8. The relative head has nothing to with the unit discharge, as a result, the head in the same section is nearly constant at different discharges with an equal or less than 4.5% relative error in comparing with the straight line slope. The step height and slope have a great influence on the relative head, especially, the higher the step height and the steeper the slope, the greater the absolute value of relative head. The experimental data confirm that the relative head of a stepped spillway varies regularly, and it is convenient for practical application and analysis, and also can provide a reference for the design of stepped spillway.. 