Experimental Investigation of Flow Behavior Over a Piano Key Weir with Varying Inlet to Outlet Crest Height

Abstract

A more recent style of hydraulic infrastructure known as a piano key weir aims to increasing the discharge of an existing dam in spillway hydraulics to release more flow and improve performance. Piano key weirs are very important to increase the current system's discharge capacity, even though they can also be very effective in reducing reservoir flood stress. There are more benefits to piano key weirs than to labyrinth weirs. There is no standard design for safe and cost-effective design because of its complex shape. This study investigates the coefficient of discharge and energy dissipation of trapezoidal piano key weirs under different geometrical configurations in free flow conditions within an open channel. Using Piano key weir model to the flow direction and varying weir crest heights (Pi/Po = 1 cm, 1.17 cm, and 1.25 cm), a number of experiments were conducted. This work aims to experimentally assess the impact of geometry on a PKW's energy dissipation (ΔE) and coefficient of discharge (Cd). To determine the Cd in each experiment, flow depths have been recorded at upstream and downstream of the weir. The collected data showed that changing the geometric parameter, or crest height, has a significant impact on Cd. The 16.5 cm step height had the lowest value of Cd, while the 20.5 cm step height had the greatest value. When considering energy dissipation, the ΔE falls with increasing H/P. When the step height was 2.3 cm, the value of ΔE was at its highest, and when it was 3.3cm, it was at its lowest.