Experimental analysis to evaluate the hydraulic performance of different shapes of broad-crested weir models

ABSTRACT The weir is a common water-management device used for measuring water flow within rivers or open channels. This study analyzes the flows over seven different shapes of broad-crested weir models, which were experimentally analyzed to evaluate the hydraulic performance of weir models depending on the discharge coefficient (Cd), the geometric shape and size (K) of the weir, as well as its shape number (n). The experimental task was conducted in a uniform-slope rectangular open-channel flume with a length of 7.5 m, a width of 0.30 m, and a depth of 0.45 m, featuring a discharge range of 1.06–13.265 l/s. The relationship between discharge coefficients and dimensionless parameters was experimentally analyzed in the form of graphs and tables using Microsoft Excel. The experimental results showed that Cd tends to increase with increasing Froude number, Reynolds number, and influence of relative weir head (Ho/P), influence of relative weir length (Ho/Lw), influence of relative weir width (Ho/B), and impact of the weir nose's roundness (Ho/R). The impact of upstream and downstream face slope on the discharge coefficient was experimentally analyzed, and experimental results show that the discharge coefficient tends to increase with decreasing upstream face slope of weir models from 90° < θ< 45°.