FLOW CHARACTERISTICS OF TRIANGULAR SIDE - WEIRS

Abstract

Side-weirs have been used extensively in irrigation, land drainage, flood protection and urban drainoge works. Several studies on rectangular side-weirs only have been reported in the past. This dissertation presents the results of an experimental investigation on the flow characteristics of triangular side-weirs at the head. of a branch channol taking off at right angle to the main channel. Both sharp-crested and broad-crested triangular side-weirs have been studied for the case of subcritic al flow in the main channel and free flow conditions in the branch channel. •de Marchi 's theory has been adopted to derive the relation for the discharge coefficient, Cm in terms of the geometric and hydraulic parmeters of triangu-lax weir and approach channel. This has been subsequently used in analysing the experimental data. The inrportnnt parameters as the value of Gm are found to be the Froude number, Pr of the main channel flow, angle of the triangular weir, G• and the ratio of head over the weir, h to length of the weir, I (in case of broad--crested weir). The influence of these par peters on Cm has been studied and relations established between these so that the discharge over the side-weir could be computed. Finally, a generalized explicit relation is also proposed to predict the discharge over a triangular side-weir with a fair degree of accuracy if Fr and h are known.