Particle-based evaluations of fish-friendliness in Kaplan turbine operations

Abstract

The concept of fish friendliness of hydroturbines relates to the effects of a unit design and its operating conditions on the success of migratory fish survival during passage through turbine flows. Most computer-based studies of fish friendliness approximate fish trajectories with streamlines; this work introduces a particle-based method to account for collisions on two typically interrogated structures: the stator and the runner. We implemented the method in various operating points of a Kaplan turbine simulated with computational fluid dynamics. The results indicated that only a small percentile of the particle sample collides severely with the stator (<0.5%) and the runner blades (<3%). The severe collisions did not exhibit any preferential distribution in the circumferential and radial directions, except for particles to collide near the outer area of the runner (near the discharge ring). This article concentrates mainly on the advantages and limitations of the particle-based method, always assessed in view of streamline-based calculations.