Abstract
Several geometric parameters influence weir discharge and it is explained in our present study. The PK weir is more efficient than rectangular labyrinth weir due to reduction in entrance losses of PK weir inlet key geometry. PK weir is a type of labyrinth weir with variation in angle. Therefore, in this paper we also discuss about labyrinth weir. PKW are compatible for constructing on existing or new spillway with lesser space requirement and structural stability. PKW are installed in order to increase the discharge capacity for a given footprint area. PKW is used to increase the overflow capacity of existing dams such as, Hazelmare dam (South Africa), Dartmouth dam (Australia). Trapezoidal piano key weirs have higher discharge efficiency than rectangular weirs and it is due to interference wedge. Cd of TPKW is influenced by L/W but Wi/Wo has least effect.
Highlights
Weirs are ordinarily used to avoid flooding, measure water discharge and help render waterways more safe by watercraft
Local submergence of labyrinth weir is observed at Ht/P =0.6, and Cd is significantly less than linear weir, but it has high discharge capacity of 270% and 180% for α=60,120 respectively
When compared with other solutions, the PKW has a number of advantages, no change of normal and maximum operating levels, minor impact on dam structure, no impact on existing gate and other mechanical components, reliability of free flow spillway, requiring little maintenance and low cost solution involving the construction of simple concrete units [49]
Summary
Weirs are ordinarily used to avoid flooding, measure water discharge and help render waterways more safe by watercraft. A few dams have little spillway limits contrasted with configuration surges. Weir structures are utilized as a part of channel, flow, and store applications for flow estimation, flow redirection, and discharge control, and they are regularly intended for nothing flow conditions i.e., the surface of tail water is underneath the weir crest.
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