Start Date

2018 4:00 PM

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Abstract

Piano Key Weirs (PKW) are non-linear weir structures, which were developed in the late 1990’s. In the following years several structures were investigated in experimental as well as numerical models and were also built in prototypes, especially in France. Thereby, PKWs represent an improvement and further development of so called Labyrinth weirs, but with an additional increase of discharge capacities and a reduced footprint. Two main PKW applications can be separated in research projects: (1) on top of dams (flood release structures) and (2) in-channel applications (replacement of regular weirs). The main difference between Labyrinth and Piano Key Weirs can be found in basic geometry components. While for Labyrinth Weirs the geometry follows a kind of accordion shape with vertical weir walls (velocity distribution close to the flow surface), the PKW design is more complex and includes sloped inlet and outlet keys, placed on a small footprint area. In this context, also the general flow characteristics are modified because the inlet and outlet keys can reach flow areas close to the river bed (for in-channel application). Hence, the velocity distribution differs majorly from those found in Labyrinth weirs – and with it resulting phenomena like e.g. scouring or sediment transport. The present paper summarizes and highlights current research investigations and state-of-the-art solutions for PKW designs and calculations – especially for in-channel applications. Based on this comprehensive literature review, future challenges for PKW research projects are specified. Topics like e.g. general flow characteristics, scale effects, downstream scouring, sediment transport, drift wood log jams, fish climb capability or concrete abrasion will be discussed in detail to identify current and further research needs in small-scaled and large-scaled experimental and numerical models.

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May 17th, 4:00 PM

Piano Key Weir Research: State-of-the-art and Future Challenges

Piano Key Weirs (PKW) are non-linear weir structures, which were developed in the late 1990’s. In the following years several structures were investigated in experimental as well as numerical models and were also built in prototypes, especially in France. Thereby, PKWs represent an improvement and further development of so called Labyrinth weirs, but with an additional increase of discharge capacities and a reduced footprint. Two main PKW applications can be separated in research projects: (1) on top of dams (flood release structures) and (2) in-channel applications (replacement of regular weirs). The main difference between Labyrinth and Piano Key Weirs can be found in basic geometry components. While for Labyrinth Weirs the geometry follows a kind of accordion shape with vertical weir walls (velocity distribution close to the flow surface), the PKW design is more complex and includes sloped inlet and outlet keys, placed on a small footprint area. In this context, also the general flow characteristics are modified because the inlet and outlet keys can reach flow areas close to the river bed (for in-channel application). Hence, the velocity distribution differs majorly from those found in Labyrinth weirs – and with it resulting phenomena like e.g. scouring or sediment transport. The present paper summarizes and highlights current research investigations and state-of-the-art solutions for PKW designs and calculations – especially for in-channel applications. Based on this comprehensive literature review, future challenges for PKW research projects are specified. Topics like e.g. general flow characteristics, scale effects, downstream scouring, sediment transport, drift wood log jams, fish climb capability or concrete abrasion will be discussed in detail to identify current and further research needs in small-scaled and large-scaled experimental and numerical models.