The purpose of this master thesis is an investigation of the current state of fish-friendly turbines (turbines which injure the fish at downstream migration at the lowest possible rate) and also an analysis of adequacy for fish passage at the current designs with the focus on the Kaplan turbine. Our main focus is an analysis of the turbine runner, which is the most problematic part of fish passage, since it is a place of high pressure changes, which increases damage to the fish’s swimming bladder,and the likeliest place for a mechanical strike. Analyzed is an actual case study of a Nedre Fiskumfoss hydro power plant in Norway, which is in the process of renovation or building a new power house with new turbines. We analyze the new solution and we compare the parameters, which impact the rate of pressure change, runner’s speed, runner’s diameter and depth of a submergence. We compare the calculated values with biological criteria for a fish’s safe passage through the turbine system. The existing Francis turbines and new Kaplan solution are compared. The result is a theoretical model or equations which allow to compare different Kaplan turbine runners on the same point of optimal or highest efficiency in the hill chart. In addition, the alternative solutions for a safer fish passage are presented, which would have a lower fish mortality rate at the same main turbine parameters.
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