Determination of losses for trash racks using numerical flow analyses

Trash racks are used in hydro power plants to protect the turbine against trash but also to protect fishes from entering the turbine. Because of fish protection, it is advantageous to have trash racks with smaller distances between bars. The reduction of the bar distances of a trash rack leads to significantly higher losses. To reduce these losses, low-loss bar profiles have been invented, e.g. by Hassinger or the IHS (Institute of Fluid Mechanics and Hydraulic Machinery). Losses of classical bar profiles show differences to modern profiles for small distances. An assessment of the losses of the low-loss bar profile invented at the IHS compared to classical bar profiles will be given.