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Article

Plunging Circular Jets: Experimental Characterization of Dynamic Pressures near the Stagnation Zone

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Platform of Hydraulic Constructions (PL-LCH), Civil Engineering Department, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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Hydraulics and Environment Department, Laboratório Nacional de Engenharia Civil (LNEC), 1700-075 Lisboa, Portugal
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Civil Engineering, Architecture and Georesources Department-CERIS, Instituto Superior Técnico (IST), Universidade de Lisboa, 1049-001 Lisboa, Portugal
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Authors to whom correspondence should be addressed.
Academic Editor: Giuseppe Pezzinga
Water 2022, 14(2), 173; https://doi.org/10.3390/w14020173
Received: 22 November 2021 / Revised: 24 December 2021 / Accepted: 29 December 2021 / Published: 9 January 2022
(This article belongs to the Section Hydraulics and Hydrodynamics)
Spillways are a requirement for dams’ safety, mainly preventing overtopping during floods. A common spillway solution involves plunging jets, which dissipate a considerable flow energy in the plunge pool. Energy dissipation has to occur in a controlled manner to avoid endangering the dam foundation and river slopes. Indeed, a scouring process in the downstream riverbed will inevitably develop until equilibrium is reached, otherwise a suitable pre-excavated or concrete lined plunge pool has to be provided. This paper focuses on experimental studies in which particular attention was paid to the dynamic pressures in the plunge pool floor at the vicinity of the jet stagnation zone sampled at 2.4 kHz. A rectangular experimental facility, 4.00 m long and 2.65 m wide, was used as plunge pool. Tests involved a vertical circular plunging jet with velocity ranging from 5 to 18 m/s and plunge pool depth ranging from 4.2 to 12.5 jet diameters. Differences in dynamic pressure measurements are highlighted between transducers located in the inner and outer regions of the jet diameter footprint. Several parameters characterizing the dynamic pressures evidence trends tied with the jet velocity that, to the authors’ knowledge, were not dealt in previous research. These can derive from the coupling effects of consequent recirculating motions and air entrainment in the limited-size plunge pool. Both effects, increasing with velocity, cause an reduction in the efficiency of the diffusing jet shear layer. This aspect deserves further investigation to achieve a better understanding and more complete characterization. View Full-Text
Keywords: spillway; plunging jet; experimental research; dynamic pressures; stagnation zone; energy dissipation; scour spillway; plunging jet; experimental research; dynamic pressures; stagnation zone; energy dissipation; scour
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MDPI and ACS Style

Jamet, G.; Muralha, A.; Melo, J.F.; Manso, P.A.; De Cesare, G. Plunging Circular Jets: Experimental Characterization of Dynamic Pressures near the Stagnation Zone. Water 2022, 14, 173. https://doi.org/10.3390/w14020173

AMA Style

Jamet G, Muralha A, Melo JF, Manso PA, De Cesare G. Plunging Circular Jets: Experimental Characterization of Dynamic Pressures near the Stagnation Zone. Water. 2022; 14(2):173. https://doi.org/10.3390/w14020173

Chicago/Turabian Style

Jamet, Grégoire, António Muralha, José F. Melo, Pedro A. Manso, and Giovanni De Cesare. 2022. "Plunging Circular Jets: Experimental Characterization of Dynamic Pressures near the Stagnation Zone" Water 14, no. 2: 173. https://doi.org/10.3390/w14020173

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