水轮机流道非恒定流对过机鱼体影响研究

Impact from unsteady flow in flow passage on fish passing through turbine

基于鱼类借助水轮机流道下行过坝时成活率较低的背景,在利用视频分析技术捕捉草鱼幼鱼通过模型轴流式水轮机下行典型路径的基础上,结合CFD数值模拟技术对水轮机流道非恒定流对过机鱼体的影响进行深入研究。结果表明,水轮机过渡过程中导叶关闭时间与过机鱼体的损伤概率有一定的相关性。随着水轮机导叶关闭时间的延长,鱼体通过水轮机下行的受压力损伤概率降低,但受压力梯度损伤的概率增加。综合比较压力及压力梯度对过机鱼体的损伤影响,表明:导叶关闭时间延长会增加对过机鱼体造成损伤的概率。因此,对于水轮机流道有过鱼需求的水电站,在不影响稳定运行的条件下,为保护鱼体安全过机,应适当降低导叶关闭时间。研究结论可对减小过机鱼体损伤概率的水轮机优化运行提供一定参考。

In accordance with the background of that the survival rate of the fish passing over dam through the flow passage of turbine is lower,the impact from the unsteady flow in the flow passage on fish passing through turbine is deeply studied herein in combination with CFD numerical simulation technology on the basis of trailing the typical downward route of the juvenile grasscarp passing through a model Kaplan turbine with the relevant video analysis technique.The result shows that the guide vane closing time during the transient process of hydraulic turbine is correlative to the damage probability of the fish passing through turbine to some extent.Along with the extension of the guide vane closing time,the damage probability of the fish passing downward through turbine caused by pressure is to be decreased,but the probability of the damage caused by pressure gradient is to be increased.With a comprehensive comparison made on the impacts from both the pressure and the pressure gradient on the damage of the fish passing through turbine,it is indicated that the extension of the guide vane closing time is to increase the probability of damage of the fish passing through turbine.Therefore,for the hydropower stations those are necessary to meet the demand from fish passing through turbine,the guide vane closing time must be properly decreased for protecting fish safely passing through turbine.The study result can provide a reference for the optimal operation of turbine to decrease the damage probability of the fish passing through turbine.