Ethohydraulische und hydronumerische Untersuchungen an Rechen und Kaplanturbinen als Beitrag zur Reduktion der Aalschädigung an Laufwasserkraftanlagen

Klopries, Elena-Maria; Schüttrumpf, Holger (Thesis advisor); Lehmann, Boris (Thesis advisor)

Aachen / Shaker (2018, 2019) [Book, Dissertation / PhD Thesis]

Page(s): 1 Online-Ressource (XXVII, 269 Seiten) : Illustrationen, Diagramme

Abstract

One of the main challenges regarding the economic and ecological use of hydropower is to reduce the impairment of downstream migrating fish at hydropower facilities. Species like the European eel that depend on free passage of river sections and, at the same time, are critically endangered have a particular need for effective and realisable mitigation measures. Most notably, this is true at rivers with a multitude of hydropower facilities like the River Moselle where the negative impact for fish accumulates in the course of reaches. Bar-rack-bypass-systems in front of turbine intakes and fish-adapted turbine management are two possible measures for fish protection. However, there is only little information to date how their ideal implementation and the efficacy at large existing hydro power plants look like. This work presents a probabilistic model of the longitudinal migration path of silver eels through a bar rack and a turbine. It calculates the possibility that a silver eel is hurt on that path. A model of the screening effect of a bar rack is provided based on data from current literature and is validated by own ecohydraulic studies. The main factors of influence on the probability that a fish passes through a bar rack and into a turbine have been proven to be the ratio of minimal body width to bar rack spacing as well as the horizontal and vertical angle of inclination. Following that, computational fluid dynamic studies have been used to develop a model of damages within the turbine. By representing the physical processes within the turbine and the fish passage through the turbine, the model allows to calculate the hydraulic strain fish experience during turbine passage. Coupling these with the vulnerability of fish to these strains, a risk of mortality is calculated. For shear stress and pressure change as two of the three main mechanisms of damage, the significant strains occur mainly in the region of the guide vanes. For collisions that are the third main mechanism of damage apart from small turbine discharges, the significant strains appear in the region of the runner. The main factors of influence that have been detected out of these studies contribute greatly to the general understanding of interdependencies and the damaging process inside a turbine. Both models are applied to the hydropower facilities at the River Moselle to calculate the effect of structural and operational measures on the eel population there. To optimise the combined use of bar racks and bypasses on the one hand and fish-adapted turbine management on the other hand, one needs to consider a multitude of parameters and one needs to analyse the actual processes that cause damages. The ecohydraluic studies and numerical simulations that have been carried out show that it is possible and beneficial for fish protection to provide conditional equations and phenomenological descriptions of damaging processes as well as parameter correlations for concrete hydropower facilities.

Identifier

  • ISBN: 978-3-8440-6202-1
  • REPORT NUMBER: RWTH-2018-229216