Pressure reduction in plunge pools by triangular wedges at high-head overfall spillways. Issue 2 (10th April 2022)

• Record Type: Journal Article
• Authors: Deng, Jun; Wei, Wangru; Duan, Hongfeng
• Is Part Of: Proceedings of ICE. Volume 175:Issue 2(2022:Apr.)
• Page Start: 78
• Page End: 88
• Publication Date: 2022-04-10
• Subjects: dams, barrages & reservoirs -- design -- hydraulics & hydrodynamics; Hydraulic engineering -- Periodicals; Water-supply engineering -- Periodicals; Water resources development -- Periodicals; 627
• DOI: 10.1680/jwama.20.00058
• Languages: English
• ISSNs: 1741-7589

Abstract

Abstract : Overfall spillways are important hydraulic structures for the release of overtopping water flows downstream of a dam. To reduce the effects of the impact of falling water in plunge pools, an overfall spillway outlet design that produces a longitudinally spreading jet is required. This study examined the effects of a triangular wedge placed at the end of an overfall spillway to deflect the water flow in the lateral direction, making the jet longitudinally diffuse before reaching the plunge pool. Laboratory data on the mean pressure coefficient were used to analyse the effects of various design parameters. An increase in the deflection ratio and a decrease in the weir crest length reduced the jet impact pressure. Compared with the impact of a rectangular jet falling into a plunge pool, an appropriate triangular wedge structure was found to improve the spreading of the impingement jet and reduce the mean dynamic pressure coefficient. By optimising the geometric design to accomplish jet impact control, the results of the present investigation may help engineers to design overfall spillways in high-head dam projects.