大型低水头轴流式水轮机流道过鱼机理研究

The dam construction blocks up the natural migratory passage of the fish. The fishes go to downstream of the river through the turbine passage may suffer the mechanical and hydrodynamic injuries which are the main problems preventing the fish going to downstream of the river through the turbine passage. This paper mainly studies the juvenile of the four major Chinese carps migratory fish in the upper stream of the Yangtze River by doing the fish hydrodynamic damage test, three-dimensional numerical simulation of turbine passage and doing the test of the fish going through the model turbine passage. This subject reveals the mechanism effect of water dynamic characteristics in Kaplan turbine passage on the migration juvenile fish, identifies the critical hydraulic factors which affects the juvenile fish passing safely through Kaplan turbine passage, establishes a model which can evaluate the suitability for the fish passing through the turbine passage based on the water dynamic characteristics analysis, optimizes the parameters of the turbine and the unit operation manner, and proposes an turbine ecological operation which can reduce the juvenile fish injury. The research results helps to clarify the feasibility find out the way for the migration fish passing through the large low head Kaplan turbine passage safely, and provides the scientific basis for recovering the migration routes of the migratory fish and restoring the ecological turbine in our country.

大坝的修建阻隔了鱼类的自然洄游通道，通过水电站水轮机流道下行的鱼类可能遭受各种机械和水动力伤害，是制约借助水轮机解决鱼类下行过坝问题中的主要瓶颈。本项目以长江中上游主要经济洄游鱼类四大家鱼幼鱼为研究对象，通过鱼体水动力损伤实验、水轮机全流道三维数值模拟、模型水轮机过鱼实验，揭示大型低水头轴流式水轮机流道水动力特性对下行幼鱼的影响机制及影响过程，识别影响家鱼幼鱼通过轴流式水轮机流道安全下行的关键水力因子，构建水轮机流道水动力特性对幼鱼安全下行的适合度评价模型，并借助适合度评价模型优化水轮机流道参数和运行参数，提出降低幼鱼损伤概率的水轮机生态运行方式。研究成果有助于阐明大型低水头轴流式水轮机流道安全过鱼的可行性及实现方法，为恢复长江主要洄游鱼类的洄游通道和我国水轮机的生态修复改造提供科学依据。

本课题以长江中上游主要洄游及经济鱼类四大家鱼幼鱼为研究对象，通过家鱼幼鱼对水轮机流道水动力单因子适应性实验、水轮机全流道三维数值模拟及模型水轮机过鱼实验，揭示大型轴流式水轮机对于通过其流道下行的四大家鱼幼鱼的损伤机理；通过对比大型低水头轴流式水轮机恒定流工况与非恒定流工况下过机鱼体的损伤状况，得出过机鱼体损伤概率与水轮机运行工况的相互关系；在满足水轮机基本发电效益的前提下，以减小过机鱼体损伤概率为目标对水轮机流道进行优化设计，为鱼类通过水轮机流道安全下行提供了有力的技术支撑，有效提高水利工程运行的生态效益。其主要成果为：（1）大型轴流式水轮机运行状况及过鱼能力状况调查研究；（2）明确四大家鱼幼鱼对水轮机流道压力及压力梯度，水力剪切等单一水动力因子的响应关系，为优化水轮机流道设计提供了生物设计标准；（3）四大家鱼幼鱼对于大型轴流式水轮机典型运行工况适应性及损伤区域，通过轴流式水轮机流道下行典型路径；（4）水轮机过流流道中转轮叶片数目及形状、泄水锥高度、导水机构等结构对过机鱼体损伤概率有较大影响；（5）对传统大型轴流式水轮机进行降低过机鱼体损伤概率的结构优化，获得减小过机鱼体损伤概率的“亲鱼型水轮机”结构并进行相关验证实验。