泄洪洞双扩型挑流消能水力特性数值计算

以某工程泄洪洞双扩型挑流鼻坎消能防冲为研究对象,基于三维不可压缩流体k-ε紊流模型,采用FLOW-3D软件对双扩型挑流鼻坎进行三维数值模拟分析,分析了下游河道流速、水舌是否直接冲击河岸,探讨了原始方案与2个优化方案的挑流鼻坎体型对河床的冲击及其水力特性,并针对不同工况时计算结果,给出了该挑流鼻坎的最佳体型,以满足消能和泄流的要求。结果表明:经多方案数值计算的对比,相比于原方案,反弧半径从64 m增加到128 m,反弧段长度增加10 m,边墙扩散宽度收窄0.4 m,挑角从43.4 °减小到25 °;调整后低水位低流量工况下水舌砸岸情况明显改善;水舌挑距从91.2 m增加到118.8 m,远离岸坡;河道左右岸最大流速分别下降0.7 m/s和1 m/s,且回流减小。研究成果可为挑流消能下游流态的改善提供一定的参考。

Numerical Simulation Analysis on the Shape Design of Double-expanded Flip Bucket

The hydraulic characteristics of a double-expanded flip bucket are simulated using FLOW-3D based on 3D incompressible fluid k-ε turbulence model. By analyzing the flow velocity in downstream channel and whether the water tongue directly impacts riverbank, we expound the hydraulic characteristics and the effects of the original flip bucket and two optimized schemes. According to the computation results under different conditions, the optimum shape of the flip bucket which meets the requirements of energy dissipation and discharge is given. Results reveal that compared with the original scheme, the radius of back arc increases from 64 m to 128 m, the length of back arc section increases by 10 m; the diffusion width of side wall is narrowed by 0.4 m, and the angle of pick-up reduces from 43.3° to 22 °. In the optimized schemes, the impact of water tongue on channel bank is significantly alleviated under the condition of low water level and flow rate; the lift distance of water tongue expands from 91.2 m to 118.8 m, away from bank slope; the maximum flow velocities on the left and right banks of the river drop by 0.7 m/s and 1 m/s respectively, and the return flow decreases. The research findings provide reference for the improvement of flow pattern downstream of flip flow energy dissipation.