| 引用本文: | 李晓超,乔超亚,谢敏萍,等.掺气坎σ值对阶梯式溢洪道的性能影响研究[J].灌溉排水学报,2023,42(7):131-137. |
| LI Xiaochao,QIAO Chaoya,XIE Minping,et al.掺气坎σ值对阶梯式溢洪道的性能影响研究[J].灌溉排水学报,2023,42(7):131-137. |
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| 摘要: |
| 【目的】进一步探索掺气坎对阶梯溢洪道的水力性能影响研究。【方法】提出了高距比σ值，并通过数值模拟，针对σ值取1/3、1/2、2/3下，l分别取0.6、0.9、1.2 m的9种阶梯溢洪道方案进行了模拟，对各方案下阶梯溢洪道的水面线、速度矢量、掺气浓度、消能率进行了分析。【结果】发现掺气坎σ值对阶梯溢洪道性能有显著影响，掺气坎位置越靠近下游，阶梯溢洪道消能率越高且越稳定，受σ值的影响越小；σ值越小，掺气坎前空腔越多；σ值越大，掺气坎后空腔越多；掺气坎后空腔有利于提升台阶竖直面水流掺气浓度；掺气坎位置越靠近下游，掺气浓度越高；掺气坎越高，掺气浓度越高。【结论】通过对掺气坎不同σ值方案下的阶梯溢洪道性能分析，结合数值模拟结果，发现掺气坎在同一σ值下，位置越靠近下游，水流流态越平顺、掺气效果越稳定、消能率越高；掺气坎在同一位置下，σ值越大，阶梯溢洪道的水流流态越平顺、掺气效果越好，但消能率却并非在最大σ值下最优，而是存在一个σ极值，且随着掺气坎向下游移动有减小趋势。 |
| 关键词: 阶梯溢洪道；掺气坎；消能率；数值模拟 |
| DOI：10.13522/j.cnki.ggps.2022471 |
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| Influence of Aeration Threshold on Performance of Stepped Spillway |
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LI Xiaochao, QIAO Chaoya, XIE Minping, XIAO Guanglei, QIN Rong, ZHANG Hao
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1. China Water Hydropower Development Co., Ltd., Chengdu 610000, China; 2. China Yangtze Power Co., Ltd.,
Wuhan 430000, China; 3. North China University of Water Resources and Electric Power, Zhengzhou 450045, China;
4. Henan Tianchi Pumped Storage Power Co. Ltd., Nanyang 474664, China
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| Abstract: |
| 【Background and Objective】Flood control is a primary task in water conservancy hubs, especially hydropower stations. Many hydropower projects in western China are characterized by high water head, large discharge, and narrow river valleys. Ensuring smooth energy dissipation during discharge is crucial to their safe operation. Stepped spillways have become a popular flood discharge structure due to its high energy dissipation rate and ability to effectively reduce the size of downstream damping. One challenge to the stepped spillways operated in large single-width flow conditions is the cavitation erosion it could create. Extensive efforts have been made to understand the flow pattern and enhance the performance of stepped spillways by improving their design. Among the various stepped spillways proposed, the aerated candy-type stepped spillway appears to be superior in mitigating cavitation erosion. However, there is limited research on the optimal height and position of the aerator. This paper aims to bridge this technology gap.【Method】Nine different stepped spillway configurations with varying aerator positions were numerically simulated to calculate the velocity vectors, spillway surface characteristics, and aeration consistency. These results were used to evaluate the hydraulic performance of each configuration.【Result】It was found that the sigma (σ) value of the aerated candy-type stepped spillway significantly influenced the performance of the spillway. The closer the aerator was positioned to the downstream end, the higher and more stable the energy dissipation rate of the stepped spillway would be, and less impact of the σ is. A smaller σ resulted in more cavities in front of the aerator, while a larger σ generated more cavities behind the aerator. The vertical plane of the lifting step resulted in a concentrated aeration flow and demonstrated the advantage of cavities after the aeration barrier. Aerator proximity to the downstream end led to higher aeration concentration; higher aeration thresholds resulted in increased aeration concentration. 【Conclusion】Numerical simulations revealed that location of the aerator and sigma value of the candy-type stepped spillway have significant impacts on performance of the spillway. |
| Key words: stepped spillway; the aerated candy; energy dissipation rate; numerical simulation |
