开敞式宽大单泄槽溢洪道水力特性及优化布置研究

Study on hydraulic characteristics simulation and optimal layout of open-wide single chute spillway

开敞式宽大单泄槽溢洪道与一般溢洪道相比易发生水流流态复杂、掺气效果差等工程安全问题。以马来西亚Baleh水电工程为例,采用VOF法与RNG k-ε双方程紊流模型对溢洪道流场进行三维数值模拟。计算分析了不同工况下溢洪道流态、流速、沿程压强等水力特性的分布规律。同时开展1∶50物理模型试验,对比分析数值模拟结果与模型试验结果发现,两者基本一致,验证了开敞式宽大单泄槽溢洪道水力特性数值模拟的准确性与可行性。进而利用紊流模型计算分析了溢洪道掺气坎的优化布置方案,结果表明:1#掺气坎抬高20 cm后,坎后掺气空腔长度由11.03 m增大至19.84 m,消能率提高了6.11%;3#掺气坎沿泄槽陡坡上移15 m后,挑流水舌冲击位置上移,减轻了对挑流鼻坎段水流流态的影响。研究结果对同类工程的优化设计有一定的借鉴作用。

Compared with the general spillway, the open spillway with a wide single chute is prone to complicated flow pattern and poor aeration effect. Taking the Baleh Hydropower Project in Malaysia as an example, this study uses the VOF method and the RNG k-ε two-equation turbulence model to carry out a three-dimensional numerical simulation of the spillway flow field. The calculation and analysis of the distribution law of the hydraulic characteristics of the spillway were made under different working conditions, such as flow pattern, velocity, and pressure along the way. At the same time, a 1∶50 physical model test was carried out. After comparative analysis, the model test results were basically consistent with the numerical simulation results, which verified the accuracy and feasibility of the numerical simulation of the hydraulic characteristics of the spillway with an open-wide single chute. Then the turbulence model was used to calculate and analyze the optimized layout of the spillway aeration sill in detail. The results show that: after the 1# aeration sill is raised by 20 cm, the length of the aeration cavity behind the sill increases from 11.03 m to19.84 m, Energy dissipation rate increased by 6.11%;after 3# aeration sill moves up 15 m along the steep slope of the chute, the impact position of the tipping water tongue moves upward, reducing the impact on the flow pattern of the tipping nose sill section. The research results have a certain reference for the optimization design of similar projects.