An approach to analyze the flow characteristics of sharp-crested triangular planform contracted weirs

Abstract

Weirs are a barrier across a river to amend its flow characteristics. Conventional weirs pose problems of submergence upstream of the weir due to large afflux required to pass the discharge downstream. The capacity of the weirs can be enhanced by increasing the crest length of the weir. Labyrinth weirs are folded in plan view to provide a longer crest length and which can easily be constructed on any existing conventional weir or spillway. The capacity and hydraulic design of labyrinth weirs depends on various factors such as aspect ratio, side wall angle, channel conditions and other geometric parameters of the weir etc. which has not been yet completely established. In this paper the results of the experimental study carried out to investigate the discharge characteristics of a sharp-crested contracted triangular planform weir under free flow conditions in a rectangular channel is presented. The efficiency of the triangular planform weirs is found better than the normal weir. A generalized discharge equation has been proposed for the given range of data and compared with Ghodsian and Ghare equations. The proposed equation is found within ±5% of the observed ones. Sensitivity of the weir, i.e., change of discharge due to unit change in head is also carried out which indicates that the weir is more sensitive at the low head and high L/B ratios. © IDOSI Publications, 2014.