Laboratory Investigation of piano key weir wall angle (in horizontal and vertical directions and simultaneously in both directions) on flow discharge coefficient

Piano key weir is a new form of nonlinear overflow that has been considered in recent years to increase the discharge coefficient and water storage in dam reservoirs, as well as flood discharge. The aim of this study is to investigate the effect of the angle of the side walls of the weir in the horizontal, vertical directions and simultaneous in both directions on the discharge coefficient. Hydraulic performance of 8 geometric parameters (W: weir width, Wi: inlet key width, Wo: outlet key width, P: weir height, L: weir length, Ht: water surface depth, α: horizontal wall angle, β: vertical wall angle) on discharge coefficient Using 6 models of PVC material, by labeling P αβ was tested in a laboratory flume. The experiments were performed on a rectangular piano key weir as a control and a trapezoidal piano key weir with P 07 10, P 90 13, P 03 90, P 03 11 and P 05 05 side wall angles. A total of 1598 data were measured to investigate the discharge coefficient and 1584 data for water level profiles. Based on the high flow results, the discharge coefficient of the trapezoidal piano key weirs in the P 05 05 model with a value of 41.6% is higher than the rectangular piano key weirs. In these models, the most influential factor on the discharge coefficient is the dimensionless geometric parameter L / W, which is based on the method of analysis of eviews statistical software by the discharge coefficient equation.