Downstream Fish migration in a Kaplan turbine – Part 2: Simulation practices and new post-processing method

Downward migrating fish can be damaged when passing through turbines in the direction upstream to downstream. 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. Transient CFD calculations were performed with different boundary conditions of the start condition for the particle tracks. The results of this kind of simulation are presented in detail. Streamlines towards the machines burst open wide. For the passage through the turbine, however, this fact has a significant influence on possible damage; it is not possible to say where the passage through the runner exactly happens, at least for the turbine configuration under investigation. For the hydraulic design, the transient calculation with particle tracks is a too time-consuming method. Based on the segmentation of volumes of zones with the pressure falling below discrete pressure values, an evaluation methodology is presented.