ABSTRACT
The main intake of the Maigrauge Dam is protected by a vertically inclined trash rack with 30 mm bar spacing. The bypass entrance for downstream fish passage is located next to the main turbine intake. A PIT tag study showed that many fish approach the bypass but only few enter it. In this project, structural measures were analyzed to improve fish protection at the turbine intake rack and bypass acceptance. To reduce rack passages, two options to electrify the rack were compared: 1) Placing electrodes on the front of the bars of the rack and 2) using the rack as a cathode and placing a row of electrodes 10 cm downstream. Based on numerical simulations of the electric field and comparison to laboratory and literature data, both setups are expected to significantly reduce rack passages. Furthermore, improvements for bypass attraction and acceptance were developed.
