Author(s): Marcelo Yudi Minoda Takenobu; Carlos Olavo Slota Ovelar; Paulo Henrique Cabral Dettmer; Marcos Vinicius Andriolo; Carolina Fontanelli

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Keywords: Physical modelling; CFD; OpenFOAM; Spillway; Air concentration

Abstract: The high dissolution of air component gases in the downstream flow of spillways might create regions with high levels of total dissolved gas (TDG), noxious to ichthyofauna. Horizontal deflectors in spillway chute is a common solution to reduce these levels. Air incorporation produced by water jet from these structures is lesser than the observed in usual spillways without deflectors, reducing fish mortality. Deflectors changes the flow pattern resulting in different spillway jet regimes downstream the deflectors. Spillway jet regimes are very sensitive and highly dependent on tailwater elevation. Physical and numerical models have been developed to evaluate hydraulic characteristics and air concentration in Colíder dam (Brazil). These models were carried out on a 1:15 geometric scale, respecting Froude similitude. Based on the open source code OpenFOAM, Detached Eddy Simulation (DES) and k-Omega SST turbulence model were used on the numerical model. Three different jet regimes have been analyzed in details: plunging flow, undular jet and surface jump. Water profiles, mean pressures and air concentration have been measured in both models. Furthermore, partial gate opening discharge coefficients were also calculated. Comparisons among both models indicated adequate results about hydraulic characteristics and moderate representation of air concentration in the flow with horizontal deflectors.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221103

Year: 2022