DISCHAGE COEFFICIENT OF OBLIQUE SIDE WEIRS

Abstract

An investigation of side-weirs, used as a diversion structures in rivers and canals, is presented. Most commonly, the side-weirs are aligned parallel to the direction of flow in the parent canal, giving an off-take angle, θ of 90 degrees. However, this study investigates performance of oblique side, weirs, that off-takes at an angle less than 90 degrees. Discharge coefficients for oblique weirs are obtained theoretically and experimentally as functions of off-take angle, θ, Fronde number in the parent channel and weir geometry. It is found that a high value of discharge coefficient can be maintained when θ lies between 60and 80 degrees. A side weir with θ equal to 70 degrees is selected for tiuther study with improved frontal apron and approach wall. It is concluded that the value of discharge coefficient can he further increased for a wide range of high Fronde numbers through these improvements.