Abstract: The present investigation aims to study the effect of channel bed slopes on energy dissipation across the different types of Piano Key Weir (PK weir or PKW) under the free-flow conditions in rigid rectangular channels. To this end, three different types (type-A, type-B, and type-C) of PKW models were tested and examined. To document and quantify this experimental investigation, a total of 270 tests were performed, including detailed observations of the flow field. The results show that the energy dissipation of all PKW models increases with the bed slopes and decreases with increasing the discharge over the weirs. In addition, the energy dissipation over the PKW varies significantly with the geometry of the weir. The type-A PKW has shown the highest energy dissipation than the other PKWs. As the bottom slope changed from Sb = 0% to 1.25%, the energy dissipation increased by about 8.5%, 9.1%, and 10.55% for type-A, type-B, and type-C, respectively.
Abstract: In this study an extensive experimental research is
carried out to develop a better understanding of the effects of Piano Key (PK) weir geometry on weir flow threshold submergence.
Experiments were conducted in a 12 m long, 0.4 m wide and 0.7 m deep rectangular glass wall flume. The main objectives were to
investigate the effect of the PK weir geometries including the weir
length, weir height, inlet-outlet key widths, upstream and
downstream apex overhangs, and slopped floors on threshold submergence and study the hydraulic flow characteristics. From the
experimental results, a practical formula is proposed to evaluate the flow threshold submergence over PK weirs.