导流隧洞出口小挑坎体型参数试验研究

Experimental Research on the Shape Parameters of Small Flip Bucket at Diversion Tunnel Outlet

采用物理模型试验方法,研究了设置于导流隧洞出口处的前置凸坎式连续挑流坎的体型参数,通过观测衔接流态、岸边流速、河床冲刷、上游水位等指标,重点对比了首部坎高与出口挑角两项体型参数。观测成果表明,首部坎高宜小于导流隧洞出口高度的10%,以减小坎高对上游水位的影响;出口挑角介于45°～60°之间,对衔接流态、河床冲刷等方面的改善明显。试验成果能为空间局促、常规消能设施布置受限、单宽流量大的山区河流导流隧洞出口消能设计提供参考。

The physical model test method is used to study the shape parameters of the front cam-type continuous ridges placed at the outlet of the diversion tunnel. By observing the connection flow state, the bank flow velocity, the riverbed erosion, the upstream water level and other indicators, the key parameters are compared. The observations show that the first ridge height should be less than 10% of the outlet height of the diversion tunnel to reduce the impact on the upstream water level.When the exit angle is between 45° and 60°, the improvement of the connection flow state and riverbed erosion is obvious. The experimental results of this paper can provide reference for the energy dissipation design of the diversion tunnel outlet of mountain rivers with narrow spaces, limited energy dissipation measures and large single width flow.