Experimental Study of Central Baffle Flume

Abstract

In this paper, the hydraulics of a central baffle flume (CBF) were experimentally studied. Extensive experimental runs were carried out to highlight the effects of different geometrical parameters such as baffle length, contraction ratio, and the length of upstream and downstream guide walls. Two different approaches, i.e., the Π theorem of dimensional analysis coupled with the incomplete self-similarity theory and the energy balance equation, were applied to deduce the stage–discharge formula of a CBF characterized by different geometrical parameters. The stage–discharge relationship deduced by the dimensional analysis approach was more accurate than that obtained by the energy approach. Furthermore, the dimensional analysis approach has the advantage of calculating discharge values explicitly. The measurements demonstrated that the flow capacity of a CBF decreased with increasing values of the central baffle length. The experiments also showed that a central baffle flume with an apex angle of 75° for upstream guide walls provides suitable hydraulic conditions at the flume entrance. The existence of downstream guide walls did not affect the stage–discharge relationship. In order to distinguish between the free and submerged flow conditions and to determine the modular limit of the flume, the dimensional analysis approach and the momentum balance method were used to formulate the submergence threshold. The analysis showed that the best model to describe the submergence threshold condition was obtained by dimensional analysis.