An Experimental Study of Flow over Rectangular Broad Crested Weir

Abstract

The main objective of this study was to investigate the flow behavior of the broad crested weir (BCW) and establish a new formula describing the discharge coefficient. In the present work, an experimental study has been carried out on twenty-five BCW physical models with various geometrical configurations and surface roughness conditions too. Accordingly, the analysis highlights that discharge coefficient (Cd) values are directly proportional to the total head (H) acting on the broad crested weir for a fixed value of weir length (Lw) and increase with the decrease of weir surface roughness. The results showed (H/Lw) is the most studied effective BCW dimensionless ratio that significantly influences the discharge coefficient. An increasing H/Lw from 0.15 to 0.35 leads to noted discharge coefficient values increasing up to 28.39%. As consequence, a new formula with a more compact and short form of expression has been developed for the BCW discharge coefficient prediction. Moreover, a reasonable agreement was noticed between the present study results and the previous research-developed models with errors of less than 10%. Considering the proposed discharge coefficient formula, the optimum hydraulic design of the new BCW model can be successfully facilitated by the extrapolation of characteristics of the idealized scale. .

Discharge Coefficient of a Two-Rectangle Compound Weir combined with a Semicircular Gate beneath it under Various Hydraulic and Geometric Conditions

“…Authors in [14] conducted a comparison between the numerical results obtained from the Flow 3D software and experimental tests to investigate the flow characteristics of a compound system comprising a vertical sharp-crested weir and gate. Authors in [15] examined the flow characteristics over a combined sharp-crowned rectangulartriangular weir. Authors in [16] employed a combined structure consisting of two triangular sections with different notch angles to measure flow rates for a range of discharges.…”

Hydraulic Jump Characteristics Downstream of a Compound Weir consisting of Two Rectangles with a below Semicircular Gate

“…In [13], the numerical results produced by the Flow 3D software were compared with experimental results to examine the flow of a compound system that consisted of a vertical sharp-crowned weir and gate. In [14], the flow characteristics over a combined sharp-crowned rectangular triangular weir were studied. In [15], a combined structure made up of two triangular parts with different notch angles was used to measure the flow rates for a wide range of discharges.…”