Author(s): Marcelo Giulian Marques, Carolina K. Novakoski, Mauricio Dai Prá, Eder D. Teixeira, Luiz A. M. Endres, Alexandre Castro Prestes, Pedro J. Moraes, Angelo F. Rigo, Alba V. B. Canellas, Jorge Matos

Linked Author(s): Marcelo Giulian Marques, alba

Keywords: Stepped spillways; Induced aeration; Deflector;

Abstract:

During floods, stepped spillways have the purpose of dissipating energy over the flow passage through the chute, minimizing stilling basins dimensions. However, stepped spillways have their utilization frequently limited to unit discharges of approximately 15 m³/s/m, due to the risk of cavitation damage. In order to increase the specific yields endured by these structures avoiding cavitation damages, some aeration elements are being studied. These elements allow a jet formation and the air can be introduced through the lower portion, in addition to the surface aeration. The present paper has the purpose of analyze the medium pressures behavior and the jet formation in a flow over stepped spillway through measures conducted on a scale reduced physical model. It was possible to notice that the jet reaches the 7th step for the higher flows and the 9th step for the lower. Furthermore, it was observed that, upstream of the jet impact location, the mean pressures were close to zero. These pressures were lower than the same measured at a stepped chute with natural aeration (without aerator elements) for the horizontal faces of the steps and higher for the vertical faces of the steps. Near the jet’s impact location, for both faces of the steps, a peak of positive pressures was observed, exceeding the same values on a chute with natural aeration. Downstream of this location, the pressures tend to the values acquired with natural aeration.

DOI: https://doi.org/10.3850/38WC092019-1569

Year: 2019