摘要
龙抬头式泄洪洞在水利水电工程中应用十分普遍,但是由于反弧段流态复杂,其产生空蚀破坏的原因尚不明晰。对不同泄洪洞体型掺气前后的工况进行三维数值计算,对其水力特性指标的分布规律进行研究。结果表明:随着落差Δz增大,反弧段流速逐步增大,水流空化数逐步减小;反弧半径R的改变对反弧段水力参数的影响有限。掺气水流的反弧段水力学指标主要取决于Δz,而受反弧半径R的影响相对较小。当Δz减小时,反弧段末端的水力参数在掺气前后变化不大,反弧段末端下游30m(等于15倍的挑坎高度)处的掺气水流的流速明显降低,空化数明显增高,掺气水流的保护作用对空腔下游部分的水力参数影响更加明显。在反弧末端有二次流出现,两侧边墙附近存在对称涡,不仅对边墙附近的流速压力分布产生一定影响,也加剧了反弧段内的水力特性的复杂程度。
Dragon-raise-head spillway tunnel is widely used in water conservancy and hydropower projects,due to its complex flow pattern at the anti-arch section the cause of cavitation damage is not clear.To better study this problem,this paper carried out three-dimensional numerical calculations on the working conditions of different spillway tunnels before and after aeration and made exploratory research on the distribution law of the hydraulic characteristics.The results showed that with the increase of dropΔzthe velocity of flow in the anti-arch section increased,and the number of cavitation decreased gradually.The change of the radius had a limited influence on the hydraulic parameters of the anti-arch section..The hydraulic parameters at the end of the anti-arc section did not change much before and after aeration when the drop ofΔzincreased.With the increase of dropΔz,the velocity of aerated flow at 30 m(equal to 15 times the height of the flip bucket)downstream of the end of the anti-arc section decreased visibly,and the number of cavitation increased apparently.The protective effect of aerated flow on the hydraulic parameters at the downstream part of the cavity was more obvious.Secondary flow occurred at the end of the arc,and symmetrical vortices exist near the sidewalls on both sides.The secondary flow phenomenon associated with the flow in the reverse arc section was a characteristic of the flow in the anti-arch section.It not only affected the velocity and pressure distribution near the sidewall but also made the hydraulic characteristics in the anti-arch section more complex.
作者
李广宁
孙双科
柳海涛
郑铁刚
郭子琪
王岑
LI Guangning;SUN Shuangke;LIU Haitao;ZHENG Tigang;GUO Ziqi;WANG Cen(China Institute of Water Resources and Hydroporuer Research,Beijing 100038,China;Agricultural University of Hebei,Baoding 071001,China;Three Gorges University,Yichang 443002,China)
出处
《南水北调与水利科技（中英文）》
CAS
北大核心
2020年第3期174-183,共10页
South-to-North Water Transfers and Water Science & Technology
基金
中国华能集团科技项目(HNKJ16-H12)
云南省2016院士自由探索项目(HY2017/D03)。
关键词
泄洪洞
掺气
反弧半径
空化数
二次流
spillway tunnel
aeration
reverse arc radius
cavitation number
secondary flow
