Overflow characteristics of streamlined weirs based on model experimentation

Weirs are a type of hydraulic structures that are used in water supply systems and irrigation networks for different purposes. These structures are categorized as different types and must be selected in respect to the hydraulic conditions to satisfy all the objectives of a project. The present study subjects to investigate the hydraulic characteristics of flow over the streamlined weirs, based on model experimentation. The streamlined weirs are a special type of weirs, designed based on the airfoil theory. These weirs have some merits compared to the other types of weirs. They have high discharge coefficient, more stability and less fluctuations of water free surface. According to the objectives of the present study, an experimental investigation was performed, using different experimental models of the streamlined weirs, designed according to the Joukowsky transform function. Experimental results inferred that for a constant flow discharge, the upstream flow heads over the streamlined weirs with different relative eccentricities are almost constant, showing an approximately constant discharge coefficient by the variation of the relative eccentricities. Furthermore, adding a downstream sloped face does not change the flow discharge coefficient. However, increasing the weir height, results in the increase of the flow head and the decrease of the flow discharge coefficient, especially, for the higher heads and the lower relative eccentricities.