Hydraulic Performance of Abrupt Expansion Transition with a Semi-Circular Dispenser

The eddies that result from the flow separation in abrupt expansion transition structures lead to serious problems in the bed and sides of the downstream channel. The head loss produced through expansion, on the other hand, is important as it affects the downstream stage. This study aimed to develop the hydraulic performance of an abrupt outlet transition at subcritical flow. Keeping the head losses at lower stages, and achieving near-uniform velocity distribution in the transverse direction by spreading the flow laterally, are the aims of this study. A new baffle column model that has not been previously investigated was adopted and installed into a sudden transition to work as a dispenser of extrusion inside the transition. This model is semi-circular in shape with the convex against the flow, by which the flow spreads and distributes across the width with increased uniformity. At the same time, this shape keeps the head losses at a minimum. The results of this attempt prove that it has considerable advantages both hydraulically and economically over using a flared wall transition. The results indicated increased uniform distribution of local velocity across the width, shorter length, and no more head loss than occurs at plain abrupt transition