Hydraulic performance analysis of piano key weirs with curvilinear keys: a numerical and experimental study

Abstract

ABSTRACT A significant number of dams worldwide are very old and thus require a reassessment of maximum flood discharges due to siltation and climate change effects. The Piano Key Weir (PKW) is a relatively new labyrinth-type weir that has emerged as a viable solution for dam rehabilitation and new projects with space constraints. While various studies have been conducted in the past to investigate the influence of geometrical parameters of PKW, there is a lack of information regarding the effect of non-linear slope profile of keys on the discharge efficiency. In this paper, ogee profiles have been introduced in the outlet keys to study their influence on the discharge coefficient. The experiments were performed at the Hydraulics Laboratory, IIT Roorkee, India, using a flume 15 m long, 0.39 m wide and 0.52 m deep. These experiments involved four PKW models with different slope profiles in the outlet key. The results of the laboratory studies and RANS model simulations indicate that the PKW models with ogee shaped outlet keys are more efficient than the linear shaped counterpart for heads higher than their design head. The maximum increase in discharge coefficient for the PKW models with curvilinear outlet keys was 9%.