Downstream Fish migration in a Kaplan turbine – Numerical Simulation and Experimental Verification

Downward migrating fish can be damaged when passing through turbines in the direction upstream to downstream. The overall influence on the fish population is still not known, but it is certainly linked to the damage potential of the turbines, the stage of maturity and the size of the migrating individuals as well as the proportion of migrating fish in relation to the total population. The main damage mechanisms are usually the contact to the turbine blade and the pressure drop in the turbine as well as shear forces, turbulence columns and others. For investigating the impacts of turbines on fish populations the most powerful hydro power plant on the river Drau in Austria (KW Annabrücke) was chosen as a case study. Investigations with living fish were carried out as well as numerical simulations. Furthermore, so called “barotrauma detections sensors (BDS)” were used for determining physical parameters during the turbine passages.