Experimental study on the Hydraulic Performance of Porous Broad-Crested Weirs with Sloping Crests

Abstract

Due to the high technical and hydraulic performance and negligible environmental adverse impact of a porous weir, this structure is a reasonable substitute for conventional impermeable solid weirs in water transmission and distribution systems. This research focused on the hydraulic performance of porous broad-crested weirs (PBCWs) with sloping crests. To this end, 30 PBCWs models in free and submerged flow conditions were designed and examined under different operation conditions. In particular, a comparative study was performed between PBCWs with and without sloping crests, the performance of which were then compared with a solid broad-crested weir (SBCW) model. Based on the results and analysis, the PBCWs with sloping crests have a more significant discharge coefficient than common PBCWs (without sloping crests), and the upstream slope has a more significant impact on the discharge coefficient than the downstream slope. In addition, the PBCWs with sloping crests are more sensitive to tailwater than common PBCWs, and thus the discharge reduction factor of the weir with the upstream crest slope is lower than that of the downstream. Finally, based on the extensive experimental results, both nonlinear multi-variable regression and gene-expression programming approaches were applied to extract empirical equations for expressing the free flow discharge coefficient and submerged flow discharge reduction factor.