Comparison of Piano Key and Rectangular Labyrinth Weir Hydraulics

Abstract

The piano key or PK weir represents a relatively new hydraulic structure in both research and practice. There is currently a limited understanding regarding the influence of the large number of PK weir geometric parameters on hydraulic performance. A specific PK weir design configuration, suggested to be highly efficient, has been presented in the literature. By using laboratory-scale physical models, the hydraulic efficiency of the recommended PK weir design was compared with that of a geometrically comparable rectangular labyrinth weir, with and without sloping floors (consistent with the PK weir geometry) installed in the inlet and outlet keys or cycles. In general, the test data showed that the PK weir was more efficient than the geometrically comparable rectangular labyrinth weir, a fact likely attributable to a reduction in entrance losses associated with the PK weir inlet key geometry.