Author(s): A. R. Kabiri-Samani; A. Ansari
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Abstract: Weirs are among the most popular and simple hydraulic structures. Although there is a wide knowledge on perpendicular weirs, few studies have been done on weirs placed obliquely to the flow direction. In this study, experiments were conducted on weirs placed obliquely in an open channel. The main objectives of this study are, to investigate flow characteristics under different weir obliqueness and examining methods for increasing the discharge capacity and effective length of oblique weirs. Oblique weirs with different angle from perpendicular to 10o from the incident flow direction are used. Also different combinations of weir angle, guide vanes and upstream inclined plates were examined and the effects of each combination on increasing the discharge over the weir compared with the results of standard weir is determined. Results show that, by increasing the oblique angle, the effective crest length of the weir increases significantly, whereas the discharge coefficient (Cd) decreases slightly. Finally, practical relations are presented on the discharge coefficient and the effective crest length of oblique weirs. Applying a group of submerged vane plates in upstream face of the weir and upstream inclined plate can increase the water discharge up to 20 and 25% respectively.
Year: 2009