ABSTRACT
ABSTRACT: Labyrinth weirs are adequate solution in dam rehabilitation projects when the storage and\or discharge capacity has to be increased. Piano key weirs (PKW) are particularly interesting due to their structure as well as their upstream and downstream flow conditions. PKW have a different geometrical shape than the classic labyrinth weirs. The keys are rectangular shaped with inclined key bottoms allowing the use of overhangs. Two different types of PKWwere defined: Type A shows two overhangs, one upstream and one downstream. Type B does not have the downstream overhangs. Physical modelling tests have showed that the efficiency of Type B is higher than of Type A. The study reveals that flow on the PKW is influenced by different geometrical parameters. The dimensional analysis allowed the development of relations between discharge capacity and the shape of the PKW.
