纵向错落差动式挑坎水力特性的研究

Study on the Hydraulic Characteristics of Vertically Scattered Upper-Lower Flip Bucket

为探究一种新型纵向错落差动式挑坎的水力特性,对此种挑流鼻坎的体形参数进行设计,其中反弧半径为10 m的低坎和5 m的高坎的起挑点均紧接在坡比为1∶1的溢洪道后,保持两种挑坎的高度相同均为0. 94 m,则可确定高挑坎挑脚为35°,低挑坎挑脚为25°,并且使得低坎的纵向长度小于高坎的纵向长度,即流经高坎的水舌在纵向上比低坎水舌优先起挑。通过Fluent中对划分网格的三维模型进行数值模拟,计算结果表明,此种新型挑坎有效加大挑距超过60%,扩大下游落水面积,有利于增加冲刷坑面积从而减轻对下游河道的局部冲刷。在明显减小鼻坎处压强的同时,没有产生易发生空蚀空化的负压区,有利于对挑流鼻坎处的保护。

In order to explore the hydraulic characteristics of a new type of vertically scattered upper-lower flip bucket, the shape parameters of this kind of flip bucket are designed with a low scallop radius of 10 m and a high scallop radius of 5 m. The picking points are all closely connected after the spillway with a slope ratio of 1∶ 1. Keeping the heights of two picks equal to0. 94 m, the upper flip bucket’s angle is 35° and the lower flip angle is 25°. Therefore, the longitudinal length of the lower flip bucket is shorter than that of the upper, the water tongue flowing through the high sill picks earlier than the low scallop tongue in the longitudinal direction. The three-dimensional model is numerically simulated by Fluent. The calculation results show that this new type of flip bucket can effectively increase the throw distance by more than 60% and expand the downstream water-fall area, which helps to increase the area of scour hole and reduce the local erosion of the downstream river. While significantly reducing the pressure at the flip bucket, there is no negative pressure zone that is prone to cavitation, which is conducive to the protection of flip bucket.