Abstract
Abstract Piano key weirs are being increasingly used for better flood passage downstream, both as a new structure or on top of hydraulic structures like a dam, to increase their discharging capacity as well as reservoir storage. Much research has been done on rectangular plan-form, while other plan-forms warrant attention. The present study focuses on two different plan geometries of PKW, i.e., rectangular (RPKW) and trapezoidal with angle α equal to 9 degrees (TPKW9) for their head-discharge relation in a wide channel of 0.984 m width under free-flow condition. Since the role of CFD is increasingly becoming prominent in present times, a numerical study using ANSYS-FLUENT was also carried out to ascertain its relevance in predicting flows around complex structures like PKW. Further, the tailgate was closed to render the PKW's outlet from partial to fully submerged conditions. The effect of these submerged outlets was studied for any changes in the discharging capacity of the PKW. The study shows RPKW to be more hydraulically efficient than TPKW9 for the model geometry. Further, the study finds that under partial to full submergence of PKW outlets, both PKW units' discharging capability remains unchanged.
Highlights
Any transverse structures constructed in rivers or any flowing water body, such as dykes, bridges, weirs, and so on, tends to affect the natural flow (Yu et al ) and create turbulence in the channel
The present study focuses on the head-discharge relationship of RPKW and TPKW9 in a channel of 0.984 m width
The present study focuses on the two different plan forms of piano key weir (PKW); that is, RPKW and TPKW9, for their head-discharge relation in a wide channel of 0.984 m width in free-flow condition
Summary
Any transverse structures constructed in rivers or any flowing water body, such as dykes, bridges, weirs, and so on, tends to affect the natural flow (Yu et al ) and create turbulence in the channel. The effect of sediment scouring around hydraulic structures like bridges, piers, and dykes has been studied by various researchers (Pandey et al , b, ; Nhu et al ; Tripathi & Pandey ). Weirs are transverse hydraulic structures used extensively for water level moderation, channel stabilization, flow discharge measurement and control and environmental improvement. For achieving these goals, the weir must have high hydraulic functioning, structural feasibility and social sustainability. Optimizing the shape to achieve a hydraulically efficient design with less cost has to be studied to arrive at a solution
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