Experimental Investigation on a System of Crossbeams As Energy Dissipator in Abruptly Expanding Channels

Several studies have demonstrated that in abruptly expanding channels phenomena of flow asymmetry can arise under certain tailwater conditions. These undesired situations are characterized by high-velocity concentrations and backward flows in the tailwater channel. This paper presents some preliminary results of an experimental investigation carried out to study the effects of a system of crossbeams for improving the flow patterns in the tailwater channel. Four different beam spacings, two system orientations and slopes, two locations, and two beam heights were tested in order to define the most adequate geometry of the dissipator. It was found that, for almost all tested configurations, the presence of the crossbeams produced a significant improvement in the flow field in the channel, in terms of velocity distribution and stability under variable downstream conditions. (C) 2015 American Society of Civil Engineers.