Experimental and numerical investigation of piano key weirs.

Piano Key Weirs (PKW) are useful overflow structures to increase discharge capacity per unit length of spillway crest for relatively small heads over the weir compared to a standard straight weir crest. PKW can be used as a side or frontal weir in many circumstances to regulate reservoir levels with small changes in water surface elevation. Nearly constant reservoir level has many advantages in optimum operation of water reservoirs for instance in maximizing hydropower production. There are several empirical formulations available in the literature to find the discharge over the PKW for a given head. However, because of large number of geometric parameters involved in the weir design, available experimental data gathered from different sources do not overlap showing significant variations indicating dependence on specific experimental conditions of each data source. There is a physical model at 1/30 scale used in this study involving three units of PKW which was constructed as a part of hydraulic model testing for the spillway of Aşağı Kaleköy Hydropower Plant which is under construction in Turkey. Head-discharge data was measured for the specific design available. Then, Flow3D was used to numerically solve flow over PKW for different configurations, one configuration being identical to that of the physical model, at the model scale. The experimental results are compared to numerical ones to validate the CFD code. It was noticed that CFD solution is very sensitive to mesh size and quality. After validation, Flow 3D was used to investigate various design configurations at prototype scale to maximize the discharge capacity of the PKW. Compared to the flat shape, having curved parapet walls increases the discharge capacity of the system by approximately 3%.
37th IAHR Congress, Kuala-Lumpur, Malezya, (13 - 18 Ağustos 2017)


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Piano Key Weir (PKW) is a special type of overflow weir which provides an improved discharge capacity with its increased crest length. Increased discharge capacity makes this weir an attractive alternative in the rehabilitation of existing spillways. After the introduction of this new weir type, many experimental and numerical studies are conducted to understand the effect of the numerous geometrical parameters on the discharge capacity. However, empirical discharge formulas suggested by different researche...
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Piano Key weirs are recently developed hydraulic structures and provide valuable benefits in discharge efficiency and dam safety. This new type of labyrinth weir is an excellent alternative for traditional labyrinth weirs with its relatively small footprint. Labyrinth weirs were developed for increasing the discharge capacities of existing dams. However, their footprint does not allow them to be placed into dam crests easily. Nevertheless, Piano Key weirs can be directly implemented on existing spillways an...
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Experimental and numerical investigation of flow under radial gates
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Radial gates are commonly used in spillways. At partial gate openings empirical equations, which were obtained from experimental work conducted in 60’s, are used to calculate the discharge passing through. However, there are some discrepancies between the discharge values obtained from these equations and the ones from numerical calculations based on finite volume method and hydraulic models. It is aimed to put forward the source of these differences. For this purpose, experiments and numerical calculations...
Citation Formats
M. Köken, İ. Aydın, and E. Haspolat, “Experimental and numerical investigation of piano key weirs.,” presented at the 37th IAHR Congress, Kuala-Lumpur, Malezya, (13 - 18 Ağustos 2017), 2017, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/75052.