Start Date

2018 4:40 PM

Creative Commons License

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

Abstract

Fixed weir types are generally passive weirs and are supposed to be more prone to hold back sediments. Few model tests have been conducted for specific prototypes of labyrinth weirs which indicate that sediments will be scoured out upstream of the weir by the turbulent action. But an attempt to generalize the findings of the studies is missing. The question that arises is whether the self-cleaning is predictable in dependence of geometry, discharge and sediment properties. The main purpose of this study is to describe and to quantify the self-cleaning process at labyrinth weirs and to predict scouring in various conditions. Therefore systematic experimental tests were performed on a physical model in the laboratory of BAW. The self-cleaning performance of a rectangular and a trapezoidal labyrinth weir are compared for different sediment types. Four sediments were tested under various flow conditions: fine quartz sand, fine gravel, medium-grained gravel and polystyrene granules. In general, the present results confirm the self-cleaning ability of labyrinth weirs. The data of the tested sediments collapse to a single curve for the densimetric Froude number Fd. Accordingly Fd is the dominant parameter and mainly affects the scouring mechanism. It can be seen that self-cleaning begins at a rectangular labyrinth weir at lower discharges compared to a trapezoidal labyrinth weir.

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Jan 1st, 4:40 PM

Sediment Transport Over Labyrinth Weirs

Fixed weir types are generally passive weirs and are supposed to be more prone to hold back sediments. Few model tests have been conducted for specific prototypes of labyrinth weirs which indicate that sediments will be scoured out upstream of the weir by the turbulent action. But an attempt to generalize the findings of the studies is missing. The question that arises is whether the self-cleaning is predictable in dependence of geometry, discharge and sediment properties. The main purpose of this study is to describe and to quantify the self-cleaning process at labyrinth weirs and to predict scouring in various conditions. Therefore systematic experimental tests were performed on a physical model in the laboratory of BAW. The self-cleaning performance of a rectangular and a trapezoidal labyrinth weir are compared for different sediment types. Four sediments were tested under various flow conditions: fine quartz sand, fine gravel, medium-grained gravel and polystyrene granules. In general, the present results confirm the self-cleaning ability of labyrinth weirs. The data of the tested sediments collapse to a single curve for the densimetric Froude number Fd. Accordingly Fd is the dominant parameter and mainly affects the scouring mechanism. It can be seen that self-cleaning begins at a rectangular labyrinth weir at lower discharges compared to a trapezoidal labyrinth weir.