家鱼幼鱼对水轮机流道水力剪切响应实验研究

Experimental study on effect of fluid shear on juveniles of four major Chinese carp species

水力剪切是鱼类通过水轮机流道下行时遭受损伤的主要原因之一。发展鱼类友好型水轮机,提高水轮机的过鱼效率,需首先明确鱼类对水轮机流道内水力剪切作用的响应关系。本研究以四大家鱼幼鱼为研究对象,设计模拟水轮机流道因流道狭窄或固体表面边界引起的水力剪切环境实验装置,对四大家鱼幼鱼分别进行承受水力剪切的响应实验。实验结果表明,四种家鱼幼鱼在受到流速应变率大于或等于2179 m·s-1m-1的射流冲击时,均出现不同程度的损伤,损伤程度随流速应变率的增大而加强。另外,鱼体受流速应变率引起的水力剪切造成的损伤程度不但与家鱼种类有关,还与射流作用于鱼体的方位有关。实验结果可作为四大家鱼幼鱼通过水轮机流道下行是否受到流速应变率引起的水力剪切损伤的判别依据,为优化水轮机亲鱼型设计和运行,有效保护四大家鱼资源提供有效支撑。

Severe fluid shear is believed to be a source of injury and mortality to fishes that pass through hydroelectric turbines. Developing fish-friendly hydroelectric turbines requires an understanding of the effect of water shear stress occurring in turbine passage on fishes. This study conducts experimental tests of this effect for the juveniles of four major Chinese carp species, using a test facility that was designed specifically for testing the response and injury degree of these fishes. The results indicate that all the four types of juveniles will suffer injuries when impacted by a water jet with flow strain no less than2179 m·s-1 m-1, and the injury degree is increased with the increasing strain. And the injury degree depends not only on the species, but on the orientation of the water jet relative to the fish body. The results can be used to estimate the possibility of the Chinese carp juveniles passing the turbine to be injured by water shear,thus helping design fish-friendly turbine systems.