Abstract: 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 than 2179 m?s-1m-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.

Key words: hydroelectric turbines, fluid shear stress, simulation experiment, juveniles of four major Chinese carp species