龙抬头式泄洪洞安全监测指标分析

基于1∶40正态水工模型,运用RNG k-ε双方程湍流模型对设计与校核2种特征洪水位下小浪底水电站2^#龙抬头式泄洪洞衔接段流场水力特性进行数值模拟,求解了该泄洪洞泄流能力、流速分布、压强分布及空化数等水力特性.同时从空化数、流速、测压管水头及洞顶余幅等角度提出了龙抬头式泄洪洞安全监测指标,并构建了龙抬头式泄洪洞安全监测预警级别.研究结果表明:流量系数、流速及测压管水头模拟值与试验值吻合较好,说明采用数值模拟可较好地求解龙抬头式泄洪洞衔接段流场水力特性.龙抬头式泄洪洞的风险程度可划分为安全、低警、中警及高警等四级预警状态.影响龙抬头式泄洪洞安全运行的安全监测指标按照权重由大到小顺序依次为空化数、测压管水头、洞顶余幅及流速.研究结果将为龙抬头式泄洪洞的优化设计与安全施工提供一定的理论指导与技术支撑.

Analysis of safety monitoring indicators of dragon-head spillway tunnel

Based on the 1∶40 normal hydraulic model experiment, the RNG k-ε two-equation turbulence model is used to analyze the hydraulic characteristics of the flow field in the connection sections of the Xiaolangdi Hydropower Station 2# dragon-head spillway tunnel under the two characteristic flood level conditions of design and verification.The hydraulic characteristics of the spillway tunnel, such as the discharge capacity, the velocity distribution, the pressure distribution and the cavitation number were analyzed. At the same time, the safety monitoring indicators of the dragon-head spillway tunnel were proposed from the perspectives of the cavitation number, the cross-section velocity, the piezometric head and the remaining space of roof, and the safety monitoring and early warning levels of the dragon-head spillway tunnel were constructed. Research conclusions: the simulated results of the flow coefficient, the cross-sectional velocity and the piezometric head were in good agreement with the experimental results, which indicated that the numerical simulation can better calculate the hydraulic characteristics of the flow field in the connection section of the dragon-head spillway tunnel. The risk degree of the dragon-head spillway tunnel can be divided into four levels of early warning status: safety, low-alarm, medium-alarm and high-alarm. The safety monitoring indicators that affect the safe operation of the dragon-head spillway tunnel in descending order of the weigh were the cavitation number, the piezometric head, the remaining space of roof and the cross-section velocity. This research will provide theoretical guidance and technical support for the optimization design and safe construction of the dragon-head spillway tunnel.